NATIONAL TOXICOLOGY PROGRAM 

Technical Report Series 

No. 451 

.~, ~t~vn(/:s e,~ 

°~22Z'~-~ 

TOXICOLOGY AND CARCINOGENESIS 

STUDIES OF NICKEL OXIDE 

(CAS NO. 1313-99-1) 

IN F344/N RATS AND B6C3F 1 MICE 

(INHALATION STUDIES) 

U.S. DEPARTMENT OF HFALTH AND HUMAN SERVICES 

Public Health Service 

National Institutes of Health 
FOREWORD 

The National Toxicology Program (NTP) is made up of four charter agencies of the U.S. Department of 

Health and Human Services (DHHS): the National Cancer Institute (NCI), National Institutes of Health; 

the National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health; the 

National Center for Toxicological Research (NCTR), Food and Drug Administration; and the National 

Institute for Occupational Safety and Health (NIOSH), Centers for Disease Control. In July 1981, the 

Carcinogenesis Bioassay Testing Program, NCI, was transferred to the NIEHS. The NTP coordinates the 

relevant programs, staff, and resources from these Public Health Service agencies relating to basic and 

applied research and to biological assay development and validation. 

The NTP develops, evaluates, and disseminates scientific information about potentially toxic and 

hazardous chemicals. This knowledge is used for protecting the health of the American people and for the 

primary prevention of disease. 

The studies described in this Technical Report Were pe.rformed under the direction of the NIEHS and were 

conducted in compliance with NTP laboratory health and safety requirements and must meet or exceed all 

applicable federal, state, and local health and safety regulations. Animal care and use were in accordance 

with the Public Health Service Policy on Humane Care and Use of Animals. The prechronic and chronic 

studies were conducted in compliance with Food and Drug Administration (FDA) Good Laboratory 

Practice Regulations, and all aspects of the chronic studies were subjected to retrospective quality 

assurance audits before being presented for public review. 

These studies are designed and conducted to characterize and evaluate the toxicologic potential, including 

carcinogenic activity, of selected chemicals in laboratory animals (usually two species, rats and mice). 

Chemicals selected for NTP toxicology and carcinogenesis studies are chosen primarily on the bases of 

human exposure, level of production, and chemical structure. The interpretive conclusions presented in 

this Technical Report are based only on the results of these NTP studies. Extrapolation of these results to 

other species and quantitative risk analyses for humans require wider analyses beyond the purview of these 

studies. Selection per se is not an indicator of a chemical's carcinogenic potential. 

These NTP Technical Reports are available for sale from the National Technical Information Service, 

U.S. Department of Commerce, 5285 Port Royal Road, Springfield, VA 22161 (703-487-4650). Single 

copies of this Technical Report are available without charge while supplies last from NTP Central Data 

Management, NIEHS, P.O. Box 12233, MD El-02, Research Triangle Park, NC 27709 (919-541-3419). 

Listings of all published reports and ongoing studies are also available from NTP Central Data 

Management. The Abstracts and other study information for 2-year studies are also available at the NTP's 

World Wide Web site: http://ntp-server.niehs.nih.gov. 
NTP TECHNICAL REPORT 

ON THE 

TOXICOLOGY AND CARCINOGENESIS 

STUDIES OF NICKEL OXIDE 

(CAS NO. 1313-99-1) 

IN F344/N RATS AND B6C3F1 MICE 

(INHALATION STUDIES) 

July 1996 

NTP TR 451 

NIH Publication No. 96-3367 

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES 

Public Health Service 

National Institutes of Health 
2 Nickel Oxide, NTP TR 451 

CONTRIBUTORS 

National Toxicology Program 

Evaluated and interpreted results and reported findings 

J.K. Dunnick, Ph.D., Study Scientist 

D.A. Bridge, B.S. 

J.R. Bucher, Ph.D. 

R.E. Chapin, Ph.D. 

M.P. Dieter, Ph.D. 

M.R. Elwell, D.V.M., Ph.D. 

T.J. Goehl, Ph.D. 

J.K. Haseman, Ph.D. 

J.R. Hailey, D.V:M. 

A. Radovskky, D.~.M., Ph.D. 

G.N. Rao, D.V.M., Ph.D. 

G.S. Travlos, D.V.M. 

D.B. Waiters, Ph.D, 

K.L. Witt, M.S., Oak Ridge Associated Universities 

Experimental Pathology Laboratories, Inc. 

Provided pathology quality assurance 

J.F. Hardisty, D.V.M., Principal Investigator 

E.T. Gaillard, M.S., D.V.M. 

Dynamac Corporation 

Prepared quality assurance audits 

S. Brecher, Ph.D., Principal Investigator 

Lovelace Inhalation Toxicology 

Research Institute 

Conducted 16-day studies, evaluated pathology findings 

R.O. 

C.H. 

J.M. 

D.G. 

Y.S. 

McClellan, D.V.M., Director 

Hobbs, D.V.M., Principal Investigator 

Benson, Ph.D., Study Director 

Burt, D.V.M. 

Cheng, Ph.D. 

F.F. Hahn, D.V.M., Ph.D. 

P.J. Haley, D.V.M. 

J.A. Pickrell, D.V.M., PhlD. 

Lovelace Inhalation Toxicology 

Research Institute 

Conducted 13-week studies, evaluated pathology findings 

R.O. McClellan, D.V.M., Director 

C.H. Hobbs, D.V.M., Principal Investigator 

J.M. Benson, Ph.D., Study Director 

D.E. Bice, Ph.D. 

D.G. Burt, D.V.M. 

Y.S. Cheng, Ph.D. 

P.J. Haley, D.V.M. 

J.A. Pickrell, D.V.M., Ph.D. 

G.M. Shopp, Jr., Ph.D. 

Conducted 2-year studies, evaluated pathology findings 

C.H. Hobbs, D.V.M., Principal Investigator 

J.M. Benson, Ph.D., Study Director 

E.B. Barr, M.S. 

D.G. Burt, D.V.M. 

Y.S. Cheng, Ph.D. 

G.L. Finch, Ph.D. 

P.J. Haley, D.V.M., Ph.D. (rats only) 

F.F. Hahn, D.V.M., Ph.D. (mice only) 

K.R. Maples, Ph.D. 

NTP Pathology Working Group 

Evaluated slides, prepared pathology report on rats 

(13 May 1994) 

M.P. Jokinen, D.V.M., Chair 

Pathology Associates, Inc. 

D. Dixon, D.V.M., Ph.D. 

National Toxicology Program 

J. Everitt, D.V.M. 

Chemical Industry Institute of Toxicology 

E.T. Gaillard, M.S., D.V.M. 

Experimental Pathology Laboratories, Inc. 

J.R. Hailey, D.V.M. 

National Toxicology Program 

R.A. Herbert, D.V.M., Ph.D. 

National Toxicology Program 

A. Radovsky, D.V.M., Ph.D 

National Toxicology Program 

J. Swenberg, D.V.M., Ph.D., Observer 

NiPERA, Inc. 
Nickel Oxide, NTP TR 451 3 

NTP Pathology Working Group 

Evaluated slides, prepared pathology report on mice 

(25 April 1994) 

M.P. Jokinen, D.V.M., Chair 

Pathology Associates, Inc. 

D. Dixon, D.V.M., Ph.D. 

National Toxicology Program 

J. Everitt, D.V.M. 

Chemical Industry Institute of Toxicology 

E.T. Galliard, M.S., D.V.M. 

Experimental Pathology Laboratories, Inc. 

J.R. Halley, D.V.M. 

National Toxicology Program 

R.A. Herbert, D.V.M., Ph.D. 

National Toxicology Program 

E.E. McConnell, D.V.M., Observer 

NiPERA, Inc. 

A. Radovsky, D.V.M., Ph.D. 

National Toxicology Program 

Analytical Sciences, Inc. 

Provided statistical analyses 

R.W. Morris, M.S., Principal Investigator 

N.G. Mintz, B.S. 

S. Rosenblum, M.S. 

Biotechnical Services, Inc. 

Prepared Technical Report 

D.D. Lambright, Ph.D., Principal Investigator 

G. Gordon, M.A. 

S.R. Gunnels, M.A. 

L.M. Harper, B.S. 

M.J. Nicholls, B.S. 

K.L. Shaw, B.A. 

S.M. Swift, B.S. 
CONTENTS 

ABSTRACT ......................................................... 5 

EXPLANATION OF LEVELS OF EVIDENCE OF CARCINOGENIC ACTIVITY ........... 10 

TECHNICAL REPORTS REVIEW SUBCOMMITTEE .............................. 11 

SUMMARY OF TECHNICAL REPORTS REVIEW SUBCOMMITTEE COMMENTS ......... 12 

INTRODUCTION ..................................................... 15 

MATERIALS AND METHODS ............................................ 37 

RESULTS .......................................................... 49 

DISCUSSION AND CONCLUSIONS ......................................... 89 

REFERENCES ....................................................... 107 

APPENDIX A Summary of Lesions in Male Rats in the 2-Year Inhalation Study 

of Nickel Oxide ............................................ 125 

APPENDIX B Summary of Lesions in Female Rats in the 2-Year Inhalation Study 

of Nickel Oxide ............................................ 171 

APPENDIX C Summary of Lesions in Male Mice in the 2-Year Inhalation Study 

of Nickel Oxide ............................................ 215 

APPENDIX D Summary of Lesions in Female Mice in the 2-Year Inhalation Study 

of Nickel Oxide ............................................ 263 

APPENDIX E Genetic Toxicology ......................................... 317 

APPENDIX F Organ Weights and Organ-Weight-to-Body-Weight Ratios ................ 321 

APPENDIX G Hematology Results ......................................... 331 

APPENDIX H Tissue Burden in Rats ....................................... 339 

APPENDIX I Tissue Burden in Mice ....................................... 343 

APPENDIX J Reproductive Tissue Evaluations 

and Estrous Cycle Characterization .............................. 347 

APPENDIX K Chemical Characterization and Generation of Chamber Concentrations ....... 351 

APPENDIX L Ingredients, Nutrient Composition, and Contaminant Levels 

in N1H-07 Rat and Mouse Ration ................................ 369 

APPENDIX M Sentinel Animal Program ..................................... 373 
ABSTRACT 

NiO 

NICKEL OXIDE 

CAS No. 1313-99-1 

Chemical Formula: NiO Molecular Weight: 74.71 

Synonyms: Bunsenite; C.I. 77777; green nickel oxide; mononickel oxide; nickel monoxide; nickel oxide sinter 75; nickel protoxide; 

nickel (II) oxide; nickel (T+) oxide; nickelous oxide 

Nickel oxide (NiO) "sinters" are used in stainless 

steel and alloy steel production. Nickel oxide was 

nominated by the National Cancer Institute to the 

NTP for testing because exposure to this form of 

nickel is prevalent in the nickel industry. Increased 

incidences of lung and nasal sinus cancers have 

occurred among workers in certain nickel refining 

facilities, and nickel oxide was studied as part of a 

class study of nickel compounds. Male and female 

F344/N rats and B6C3F~ mice were exposed to 

nickel oxide (high temperature, green nickel oxide; 

mass median diameter 2.2 ± 2.6/zm; at least 99% 

pure) by inhalation for 16days, 13 weeks., or 

2 years. Genetic toxicology studies were conducted 

in peripheral blood of B6C3F~ mice exposed to nickel 

oxide for 13 weeks. 

16-DAY STUDY IN RATS 

Groups of five male and five female F344/N rats 

were exposed to 0, 1.2, 2.5, 5, 10, or 30 mg nickel 

oxide/m 3 (equivalent to 0, 0.9, 2.0, 3.9, 7.9, or 

23.6 mg nickel/m 3) by inhalation for 6 hours per day, 

5 days per week for a total of 12 exposure days 

during a 16-day period. Additional groups of 

five male and five female rats were exposed to 0, 

1.2, 5, or 10 mg/m 3 for tissue burden studies. All 

core study rats survived until the end of the study, 

final mean body weights of exposed male and female 

rats were similar to those of the controls, and there 

were no clinical findings related to nickel oxide 

exposure. Absolute and relative lung weights of 

male and female rats exposed to 10 or 30 mg/m 3 

were significantly greater than those of the controls. 

Pigment particles in alveolar macrophages or within 

the alveolar spaces were observed in the lungs of exposed groups of males and females. Chronic-active 

inflammation and accumulation of macrophages in 

alveolar spaces of the lungs and hyperplasia in the 

respiratory tract lymph nodes were most severe in 10 

and 30 mg/m 3 males and females. Hyperplasia of 

bronchial lymph nodes occurred in 30 mg/m ~ rats. 

Atrophy of the olfactory epithelium was observed in 

one male and one female exposed to 30 mg/m 3. The 

concentrations of nickel oxide in the lungs of exposed 

groups of rats were greater than those in the lungs of 

control groups (males, 42 to 267 #g nickel/g lung; 

females, 54 to 340 #g/g lung). 

16-DAY STUDY IN MICE 

Groups of five male and five female B6C3F~ mice 

were exposed to 0, 1.2, 2.5, 5, 10, or 30 mg nickel 

oxide/m 3 by inhalation for 6 hours per day, 5 days 

per week for a total of 12 exposure days during a 

16-day period. Additional groups of five male and 
6 Nickel Oxide, NTP TR 451 " 

five female mice were exposed to 0, 1.2, 2.5, or 

5 mg/m 3 for tissue burden studies. No exposurerelated deaths occurred among core study mice, and 

final mean body weights of exposed male and female 

mice were similar to those of the controls. There 

were no chemical-related clinical findings. Pigment 

particles were presem in the lungs of mice exposed 

to 2.5 mg/m 3 or greater. Accumulation of 

macrophages in alveolar spaces was observed in the 

lungs of 10 and 30 mg/m 3 males and females. The 

concentrations of nickel oxide in the lungs of exposed 

groups of mice were significantly greater than those 

in the lungs of control animals (males, 32 to 84/zg 

nickel/g lung; females, 31 to 71 /zg/g lung). 

13-WEEK STUDY IN RATS 

Groups of 10 male and 10 female F344/N rats were 

exposed to 0, 016, 1.2, 2.5, 5, or 10 mg nickel 

oxide/m 3 (equivalent to 0, 0.4, 0.9, 2.0, 3.9, or 

7.9 mg nickel/m 3) by inhalation for 6 hours per day, 

5 days per week for 13 weeks. Additional groups of 

18 male and 18 female rats were exposed to 0, 0.6, 

2.5, or 10 mg/m 3 for tissue burden studies. No 

exposure-related deaths occurred among core study 

rats, final mean body weights of exposed male and 

female rats were similar to those of the controls, and 

no clinical findings in any group were related to 

nickel oxide exposure. Lymphocyte, neutrophil, 

monocyte, and erythrocyte counts; hematocrit values; 

and hemoglobin and mean cell hemoglobin concentrations in exposed rats were minimally to m!ldly 

greater than those of the controls; these differences 

were most pronounced in females. Mean cell volumes in exposed rats were generally less than those 

in the controls. Absolute and relative lung weights 

of exposed groups of males and females were 

generally significantly greater than those of controls. 

Chemical-related nonneoplastic lesions were observed 

in the lungs of male and female rats exposed to 

concentrations of 2.5 mg/m 3 or higher, and the 

severity of these lesions, generally increased with 

exposure concentration. Accumulation of alveolar 

macrophages, many of which contained black, 

granular pigment, was generally observed in all 

exposed groups of males and females, and increased 

incidences of inflammation occurred in males and 

females exposed to 2.5 mg/m 3 or higher. In addition, lymphoid hyperplasia and pigment occurred in 

the bronchial and mediastinal lymph nodes of 2.5, 5, 

and 10 mg/m a males and females. 

The concentration of nickel oxide in the lungs of 0.6, 

2.5, and 10 mg/m 3 males was greater than in the 

lungs of controls at 4, 9, and 13 weeks, and nickel 

continued to accumulate in the lung at the end of the 

13-week exposures (4 weeks, 33 to 263 /~g nickel/g 

lung; 9 weeks, 53 to 400/~g/g lung; 13 weeksl 80 to 

524/~g/g lung). 

13-WEEK STUDY IN MICE 

Groups of 10 male and 10 female B6C3F~ mice were 

exposed to 0, 0.6, 1.2, 2.5, 5, or 10 mg nickel 

oxide/m 3 by inhalation for 6 hours per day, 5 days 

per week for 13 weeks. Additional groups of six 

male and six female mice were exposed to 0, 0.6, 

2.5, or 10 mg/m 3 for tissue burden studies. No 

exposure-related deaths occurred among core study 

animals, final mean body weights of exposed male 

and female mice were similar to those of the controls, and no clinical findings in any group were 

related to nickel oxide exposure. Hematocrit values 

and erythrocyte counts in 5 and 10 mg/m 3 females 

were minimally greater than those of the controls, as 

was the hemoglobin concentration in 5 mg/m 3 

females. Absolute and relative lung weights of 

10 mg/m 3 males and females were significantly 

greater than those of controls, and absolute and 

relative liver weights of 10 mg/m 3 males were 

significantly less than those of controls. 

Accumulation of alveolar macrophages, many of 

which contained pigment particles, occurred in all 

groups of mice exposed to nickel oxide. Inflammation (chronic active perivascular infiltrates or granulomatous) occurred in 2.5, 5, and 10 mg/m 3 males 

and females. In addition, lymphoid hyperplasia and 

pigment occurred in the bronchial lymph nodes of 

males and females exposed to 2.5 mg/m 3 or higher. 

The concentration of nickel in the lung was greater 

than that of controls in 0.6, 2.5, and 10 mg/m 3 males 

at. 13 weeks (42 to 736/~g nickel/g lung). 
Nickel Oxide, NTP TR 451 7 

2-YEAR STUDY IN RATS 

Survival, Body Weights, Clinical Findings, 

and Hematology 

Groups of 65 male and 65 female F344/N rats were 

exposed to 0, 0.62, 1.25, or 2.5 mg nickel oxide/m 3 

(equivalent to 0, 0.5, 1.0, or 2.0 mg nickel/m 3) by 

inhalation for 6 hours per day, 5 days per week for 

104 weeks. Survival of exposed male and female 

rats was similar to that of the controls. Mean body 

weights of 1.25 mg/m 3 females and 2.5 mg/m 3 males 

and females were slightly lower than those of the 

controls during the second year of the study. No 

chemical-related clinical findings were observed in 

male or female rats during the 2-year study. No 

chemical-related differences in hematology 

parameters were observed in male or female rats at 

the 15-month interim evaluation. 

Pathology Findings 

Absolute and relative lung weights of 1.25 and 

2.5 mg/m 3 males and females were significantly 

greater than those of the controls at 7 and 15 months. 

At 2 years, there were exposure-related increased 

incidences of alveolar/bronchiolar adenomas or 

alveolar/bronchiolar adenoma or carcinoma 

(combined) in males and females. Incidences of 

atypical alveolar epithelial hyperplasia in the lungs 

generally increased with increasing exposure concentration in male and female rats. Chronic inflammation of the lung was observed in most exposed rats at 

7 and 15 months and at 2 years; the incidences in 

exposed males and females at 2 years were significantly greater than those in the controls, and the 

severity of the inflammation increased in exposed 

groups. The incidences of pigmentation in the 

alveolus of exposed groups of males and females 

were significantly greater than those of the controls 

at 7 and 15 months and at 2 years. 

Pigmentation in the bronchial lymph nodes similar to 

that in the lungs was observed in all exposure groups 

with the exception of 0.62 mg/m 3 males and females 

at 7 months. Lymphoid hypelrplasia was observed in 

the bronchial lymph nodes of 1.25 and 2.5 mg/m 3 

males and females at 7 and 15 months, and the 

incidence at 2 years generally increased with exposure concentration. 

At 2 years, there was an exposure-related increase in 

the incidence of benign pheochromocytoma in males 

and females. The incidences of benign pheochromocytoma and adrenal medulla hyperplasia in 2.5 mg/m 3 

females and the incidence of benign or malignant 

pheochromocytoma (combined) in 2.5 mg/m 3 males 

were significantly greater than those in the controls. 

Tissue Burden Analyses 

Nickel concentrations in the lung of exposed rats 

were greater than those in the controls at 7 and 

15 months (7 months, 173 to 713/zg nickel/g lung; 

15 months, 262 to 1,116 /zg/g lung), and nickel 

concentrations increased with increasing exposure 

concentration and with time. 

2-YEAR STUDY IN MICE 

Survival, Body Weights, Clinical Findings, 

and Hematology 

Groups of 74 to 79 B6C3F1 mice were exposed to 0, 

1.25, 2.5, or 5 mg nickel oxide/m 3 by inhalation for 

6 hours per day, 5 days per week for 104 weeks. 

Survival of exposed male and female mice was 

similar to that of the controls. Mean body weights of 

5 mg/m 3 females were slightly lower than those of 

the controls during the second year of the study. No 

chemical-related clinical findings were observed in 

male or female mice during the 2-year study. No 

chemical-related differences in hematology parameters were observed in male or female mice at the 

15-month interim evaluation. 

Pathology Findings 

At 2 years, the incidence of alvcolar/bronchiolar 

adcnoma in 2.5 mg/m 3 females was significantly 

greater than that of the controls, as was the incidence 

of alveolar/bronchiolar adenoma or carcinoma 

(combined) in 1.25 mg/m 3 females. Generally, 

incidences of chronic inflammation increased with 

exposure concentration in males and females at 7 and 

15 months. Bronchialization of minimal severity in 

exposed animals and proteinosis were first observed 

at 15 months. At 2 years, the incidences of chronic 

inflammation, alveolar epithelial hyperplasia, and 

proteinosis in exposed groups of males and females 

were significantly greater than those of the controls. 

The severity of chronic inflammation increased with 

exposure concentration in females, and proteinosis 

was most severe in 5 mg/m 3 males and females. 

Pigment occurred in the lungs of nearly all exposed 
8 Nickel Oxide, NTP TR 451 

mice at 7 and 15 months and at 2 years, and the 

severity increased with exposure c'~ncentration. 

Lymphoid hyperplasia occurred in two animals after 

7 months; at 15 months, lymphoid hyperplasia 

occurred in males exposed to 2.5 and 5 mg/m 3 and in 

all exposed groups of females. At 2 years, lymphoid 

hyperplasia occurred in some control animals, but 

this lesion was still observed more often in exposed 

males and females and the incidence increased with 

exposure concentration. Pigmentation was observed 

in the bronchial lymph nodes of exposed males and 

females at 7 and 15 months and in nearly all exposed 

animals at 2 years. 

Tissue Burden Analyses 

Nickel concentrations in the lungs of exposed mice 

were greater than those in the controls at 7 and 

15 months (7 months, 162 to 1,034 ~g nickel/g lung; 

15 months, 331 to 2,258 #g/g lung), and nickel 

concentrations increased with increasing exposure 

concentration and with time. 

GENETIC TOXICOLOGY 

No increase in the frequency of micronucleated 

normochromatic erythrocytes was observed in peripheral blood samples from male or female mice 

exposed to nickel oxide. 

CONCLUSIONS 

Under the conditions of these 2-year inhalation 

studies, there was some evidence of carcinogenic 

activity* of nickel oxide in male F344/N rats based 

on increased incidences of alveolar/bronchiolar 

adenoma or carcinoma (combined) and increased 

incidences of benign or malignant pheochromocytoma 

(combined) of the adrenal medulla. There was some 

evidence of carcinogenic activity, of nickel oxide in 

female F344/N rats based on increased incidences of 

alveolar/bronchiolar adenoma or carcinoma (combined) and increased incidences of benign pheochromocytoma of the adrenal medulla. There was no 

evidence of carcinogenic activity of nickel oxide in 

male B6C3F1 mice exposed to 1.25, 2.5, or 5 mg/m 3. 

There was equivocal evidence of carcinogenic activity 

of nickel oxide in female B6C3Fi mice based on 

marginally increased incidences of alveolar/ 

bronchiolar adenoma in 2.5 mg/m 3 females and of 

alveolar/bronchiolar adenoma or carcinoma (combined) in 1.25 mg/m 3 females. 

Exposure of rats to nickel oxide by inhalation for 

2 years resulted in inflammation and pigmentation in 

the lung, lymphoid hyperplasia and pigmentation in 

the bronchial lymph nodes, and hyperplasia of the 

adrenal medulla (females). Exposure of mice to 

nickel oxide by inhalation for 2 years resulted in 

bronchialization, proteinosis, inflammation, and 

pigmentation in the lung and lymphoid hyperplasia 

and pigmentation in the bronchial lymph nodes. 

* Explanation of Levels of Evidence of Carcinogenic Activity is on page 10. A summary of the Technical Reports Review Subcommittee 

comments and the public discussion on this Technical Report appears on page 12. 
Nickel Oxide, NTP TR 451 9 

Summary of the 2-Year Carcinogenesis and Genetic Toxicology Studies of Nickel Oxide 

Male Female Male Female 

F344/N Rats F344/N Rats B6C3F~ Mice B6C3F~ Mice 

Exposure 0, 0.62, 1.25, or 0, 0.62, 1.25, or 0, 1.25, 2.5, or 5 mg 

concentrations 2.5 mg nickel 2.5 mg nickel nickel oxide/m 3 (0, 

oxide/m 3 (0, 0.5, 1.0, oxide/m 3 (0, 0.5, 1.0, 1.0, 2.0, or 3.9 mg 

or 2.0 mg nickel/m 3) or 2.0 mg nickel/m 3) nickel/m 3) 

0, 1.25, 2.5, or 5 mg 

nickel oxide/m ~ (0, 

1.0, 2.0, or 3.9 mg 

nickel/m ~) 

Body weights 2.5 mg/m 3 group 1.25 and 2.5 mg/m 3 Exposed groups 5 mg/m 3 group 

slightly lower than groups slightly lower similar to controls slightly lower than 

controls than controls controls 

2-Year survival 14/54, 15/53, 15/53, 21/53, 26/53, 20/53, 19/57, 23/67, 29/66, 41/64, 40/66, 42/63, 

rates 12/52 26/54 23/69 38/64 

Lung: chronic 

inflammation (28/54, 

53/53, 53/53, 52/52); 

pigment (1/54, 53/53, 

53/53, 52/52) 

Bronchial lymph node: 

lymphoid hyperplasia 

(0/52, 7/51, 10/53, 

18/52); pigment (0/52, 

45/51, 51/53, 51152) 

Nonneoplastic 

effects 

Lung: alveolar/ 

bronchiolar adenoma 

or carcinoma or 

squamous cell 

carcinoma (1/54, 1/53, 

6/53, 4/52) 

Adrenal medulla: 

benign or malignant 

pheochromocytoma 

(27/54, 24152, 27153, 

35/52) 

Neoplastic effects 

Uncertain f'mdings None 

Lung: chronic 

inflammation (18/53, 

52/53, 53/53, 54/54); 

pigment (0/53, 52/53, 

53/53, 54/54) 

Bronchial lymph node: 

lymphoid hyperplasia 

(1/49, 5/50, 20/53, 

13/52); pigment (0/49, 

43/50, 52/53, 47152) 

Adrenal medulla: 

hyperplasia (8/51, 

12/52, 14/53, 22/53) 

Lung: alveolar/ 

bronchiolar adenoma 

or carcinoma (1/53, 

0/53, 6/53, 5/54) 

Adrenal medulla: 

benign 

pheochromocytoma 

(4/51, 7/52, 6/53, 

18/53) 

bronchialization (0/57, 

24/67, 40/66, 40/69); 

proteinosis (0/57, 

12/67, 22/66, 43/69); 

chronic inflammation 

(0/57, 21/67, 34/66, 

55/69); pigment (0/57, 

65/67, 66/66, 68/69); 

Bronchial lymph node: 

lymphoid hyperplasia 

(5/45, 18/56, 28/61, 

33/62); pigment (0/45, 

55/56, 61/61, 60/62) 

None 

None None 

Some evidence No evidence 

Negative in male and female mice 

Level of evidence Some evidence 

of carcinogenic 

activity 

Genetic toxicology 

Micronucleated erythrocytes 

Mouse peripheraal blood in vivo: 

Lung: 

bronchialization (0/64, 

35/66, 39/63, 40/64); 

proteinosis (0/64, 

8/66, 17/63, 29/64); 

chronic inflammation 

(7/64, 43/66, 53/63, 

52/64); pigment (0/64, 

64/66, 61/63, 64/64); 

Bronchial lymph node: 

lymphoid hyperplasia 

(14/54, 37/63, 40/59, 

44/62); pigment (0/54, 

58/63, 56/59, 60/62) 

None 

Lung: alveolar/ 

bronchiolar adenoma 

(2/64, 4/66, 10/63, 

3/64); alveolar/ 

bronchiolar adenoma 

or carcinoma (6/64, 

15/66, 12/63, 8/64) 

Equivocal evidence 
10 Nickel Oxide, NTP TR 451 

EXPLANATION OF LEVELS OF EVIDENCE OF CARCINOGENIC ACTIVITY 

The National Toxicology Program describes the results of individual experiments on a chemical agent and notes the strength of the evidence 

for conclusions regarding each study. Negative results, in which the study animals do not have a greater incidence of neoplasia than control 

animals, do not necessarily mean that a chemical is not a carcinogen, inasmuch as the experiments are conducted under a limited set of 

conditions. Positive results demonstrate that a chemical is carcinogenic for laboratory animals under the conditions of the study and indicate 

that exposure to the chemical has the potential for hazard to humans. Other organizations, such as the International Agency for Research on 

Cancer, assign a strength of evidence for conclusions based on an examination of all available evidence, including animal studies such as 

those conducted by the NTP, epidemiologic studies, and estimates of exposure. Thus, the actual determination of risk to humans from 

chemicals found to be carcinogenic in laboratory animals requires a wider analysis that extends beyond the purview of these studies. 

Five categories of evidence of carcinogenic activity are used in the Technical Report series to summarize the strength of the evidence 

observed in each experiment: two categories for positive results (clear evidence and some evidence); one category for uncertain findings 

(equivocal evidence); one category for no observable, effects (no evidence); and one category for experiments that cannot be evaluated 

because of major flaws (inadequate study). These categories of interpretative conclusions were first adopted in June 1983 and then revised 

in March 1986 for use in the Technical Report series to incorporate more specifically the concept of actual weight of evidence of 

carcinogenic activity. For each separate experiment (male rats, female rats, male mice, female mice), one of the following five categories is 

selected to describe the findings. These categories refer to the strength of the experimental evidence and not to potency or mechanism. 

• Clear evidence of carcinogenic activity is demonstrated by studies that are interpreted as showing a dose-related 

(i) increase of malignant neoplasms, (ii) increase of a combination of malignant and benign neoplasms, or (iii) marked increase 

of benign neoplasms if there is an indication from this or other studies of the ability of such tumors to progress to malignancy. 

• Some evidence of carcinogenic activity is demonstrated by studies that are interpreted as showing a chemical-related 

increased incid~hce of neoplasms (malignant, benign, or combined) in which the strength of the response is less than that 

required for clear evidence. 

• Equivocal evidence of carcinogenic activity is demonstrated by studies that are interpreted as showing a marginal increase 

of neoplasms that may be chemical related. 

• No evidence of carcinogenic activity is demonstrated by studies that are interpreted as showing no chemical'-related 

increases in malignant or benign neoplasms. 

• Inadequate study of carcinogenic activity is demonstrated by studies that, because of major qualitative or quantitative 

limitations, cannot be interpreted as valid for showing either the presence or absence of carcinogenic activity. 

When a conclusion statement for a particular experiment is selected, consideration must be given to key factors that would extend the actual 

boundary of an individual category of evidence. Such consideration should allow for incorporation of scientific experience and current 

understanding of long-term carcinogenesis studies in laboratory animals, especially for those evaluations that may be on the borderline 

between two adjacent levels. These considerations should include: 

• adequacy of the experimental design and conduct; 

• occurrence of common versus uncommon neoplasia; 

• progression (or lack thereof) from benign to malignant neoplasia as well as from preneoplastic to neoplastic lesions; 

• some benign neoplasms have the capacity to regress but,others (of the same morphologic type) progress. At present, it is 

impossible to identify the difference. Therefore, where progression is known to be a possibility, the most prudent course 

is to assume that benign neoplasms of those types have the potential to become malignant; 

• combining benign and malignant tumor incidence known or thought to represent stages of progression in the same organ or 

tissue; 

• latency in tumor induction; 

• multiplicity in site-specific neoplasia; 

• metastases; 

• supporting information from proliferative lesions (hyperplasia) in the same site of neoplasia or in other experiments (same 

lesion in another sex or species); 

• presence or absence of dose relationships; 

• statistical significance of the observed tumor increase; 

• concurrent control tumor incidence as well as the historical control rate and variability for a specific neoplasm; 

• survival-adjusted analyses and false positive or false negative concerns; 

• structure-activity correlations; and 

• in some cases, genetic toxicology. 
Nickel Oxide, NTP TR 451 11 

NATIONAL TOXICOLOGY PROGRAM BOARD OF SCIENTIFIC COUNSELORS 

TECHNICAL REPORTS REVIEW SUBCOMMITTEE 

The members of the Technical Reports Review Subcommittee who evaluated the draft NTP Technical Report on nickel oxide on 

November 29, 1994, are listed below. Subcommittee members serve as independent scientists, not as representatives of any institution, 

company, or governmental agency. In this capacity, subcommittee members have five major responsibilities in reviewing NTP studies: 

• to ascertain that all relevant literature data have been adequately cited and interpreted, 

• to determine if the design and conditions of the NTP studies were appropriate, 

• to ensure that the Technical Report presents the experimental results and conclusions fully and clearly, 

• to judge the significance of the experimental results by scientific criteria, and 

• to assess the evaluation of the evidence of carcinogenic activity and other observed toxic responses. 

Arnold L. Brown, M.D., Chair 

University of Wisconsin Medical School 

Madison, WI 

Thomas L. Goldsworthy, Ph.D. 

Department of Environmental Pathology and Toxicology 

Chemical Industry Institute of Toxicology 

Research Triangle Park, NC 

Meryl H. Karol, Ph.D.* 

Department of Environmental Occupational Health 

University of Pittsburgh 

Pittsburgh, PA 

Curtis D. Klaassen, Ph.D., Principal Reviewer 

Department of Pharmacology and Toxicology 

University of Kansas Medical Center 

Kansas City, KS 

Claudia S. Miller, M.D. 

University of Texas Health Sciences Center 

San Antonio, TX 

Janardan K. Reddy, M.D., Principal Reviewer* 

Department of Pathology 

Northwestern University Medical School 

Chicago, IL 

Irma Russo, M.D. 

Fox Chase Cancer Center 

Philadelphia, PA 

Louise Ryan, Ph.D. 

Division of Biostatistics 

Harvard School of Public Health and 

Dana-Farber Cancer Institute 

Boston, MA 

Robert E. Taylor, M.D., Ph.D. 

Department of Pharmacology 

Howard University College of Medicine 

Washington, DC 

Mary Jo Vodicnik, Ph.D.* 

Lilly MSG Development Center 

Belgium 

Jerrold M. Ward, D.V.M., Ph.D., Principal Reviewer 

National Cancer Institute 

Frederick, MD 

* Did not a~end 
12 Nickel Oxide, NTP TR 451 

SUMMARY OF TECHNICAL REPORTS 

On November 29, 1994, the draft Technical Report 

on the toxicology and carcinogenesis studies of nickel 

oxide received public review by the National Toxicology Program's Board of Scientific Counselors' 

Technical Reports Review Subcommittee. The 

review meeting was held at the National Institute of 

Environmental Health Sciences, Research Triangle 

Park, N.C. 

Dr. J.K. Dunnick, NIEHS, introduced the toxicology 

and carcinogenesis studies of nickel oxide by discussing the uses of the chemical and rationale for study, 

describing the experimental design, reporting on 

survival and body weight effects, and commenting on 

compound-related nonneoplastic lesions in rats and 

mice. The proposed conclusions were some evidence 

of carcinogenic activity in male and female 

• F344/N rats, no evidence of carcinogenic activity .in 

male B6C3F1 mice, and equivocal evidence of carcinogenic activity in female B6C3F1 mice. 

Dr. Klaassen, a principal reviewer, agreed with the 

proposed conclusions. He asked why interim evaluations were conducted at 7 and 15 months. 

Dr. Dunnick replied that a large database exists for 

these time points, and they were chosen with the 

intent to examine the progression of lesions and lung 

nickel levels. Dr. Klaassen asked why Shirley's test 

was used for the statistical evaluation of nickel lung 

burden parameters. Dr. J.K. Haseman, NIEHS, 

explained that lung burden data are not normally 

distributed; therefore, a test using rank-based 

methods (Shirley's test) was considered to be most 

appropriate. 

Dr. Ward, the second principal reviewer, agreed with 

the proposed conclusions for male and female rats 

and male mice. But, he suggested a conclusion of no 

evidence of carcinogenic activity for female mice 

based on the lack of dose response, the absence of 

any increase in neoplasm multiplicity, and the 

presence of statistical significance only for alveolar/ 

bronchiolar adenoma or carcinoma (combined) in 

1.25 mg/m 3 females. Dr. Ward also noted that 

although the increase in nickel lung burden measurements was dose related, neoplasm incidence was not. 

Dr. Haseman said that the lack of a dose response in 

5 mg/m 3 females might have been due to significantly 

REVIEW SUBCOMMITTEE COMMENTS 

increased lung weights, adding that a significant 

correlation between increased lung weights and 

decreased lung neoplasm incidence was consistently 

observed in the three NTP nickel studies. Dr. Ward 

noted that in the present studies a high incidence of 

chronic inflammation of the lung was observed in 

control rats but not in control, mice, and he asked if 

these spontaneous lesions were more specifically 

focal alveolar macrophages rather than chronic 

inflammatory lesions resulting from persistent toxins. 

Dr. M.R. Elwell, NIEHS, said the background 

inflammatory lesions in control animals were morphologically different from those in exposed animals 

and were primarily increases in the number of macrophages. 

Because Dr. Reddy, the third principal reviewer, was 

unable to attend the meeting, Dr. L.G. Hart, NIEHS, 

read his review into the record. Dr. Reddy agreed 

with the proposed conclusions, although he believed 

the data for female mice supported a call of some 

evidence of carcinogenic activity. He expressed 

concern that the highest exposure level selected for 

rats (2.5 mg/m 3) was too low, and therefore the 

conclusion of some evidence was conservative. 

Ms. D. Sivulka, executive director of the Nickel 

Producers Environmental Research Association, Inc. 

(NiPERA), commented on the discussion of evidence 

for nickel toxicity and carcinogenesis in humans and 

the presentation of the significance of findings 

relative to existing threshold limit values (TLVs). 

Ms. Sivulka said that because conclusions in the 

report were based on existing TLVs, an implication 

could be made that current regulations are not protective of workers exposed to nickel compounds. 

Ms. Sivulka discussed the cohorts of workers 

exposed to nickel compounds that have been examined, and she said that the information obtained from 

these examinations shows no evidence of nickelrelated increases in the incidence of nonneoplastic 

lesions in workers exposed to low nickel levels. 

Dr. Miller noted that TLVs are based to some degree 

on data obtained from animal studies. Dr. Russo 

asked if any of the human studies cited by NiPERA 

had corrected for confounding factors such as alcohol 

or tobacco exposure. Ms. Sivulka said they had not, 
Nickel Oxide, NTP TR 451 13 

but added that the incidence of neoplasia in workers 

exposed to nickel compounds could not be attributed 

solely to factors such as cigarette smoking. 

Dr. Goldsworthy noted that nickel measurements 

were generally made without regard to form or 

species. Ms. Sivulka agreed, but added that NiPERA 

officials support exposure measurements and speciation analyses. Dr. Miller asked that information 

interpreting animal studies in terms of likely human 

exposure be added to the abstract of the Technical 

Report. Dr. R.A. Griesemer, NIEHS, said the 

report deals with a specific set of experiments and 

does not base conclusions on other animal or human 

studies. Dr. W.T. Allaben, NCTR, noted that the 

discussion section of the report is the appropriate 

area to speculate on such issues. He said it was the 

regulatory agencies' role to determine the significance of the nickel compound studies with regard to 

human risk. 

Dr. Klaassen moved that the Technical Report on 

nickel oxide be accepted with the revisions discussed 

and with the conclusions as written for male and 

female rats, some evidence of carcinogenic activity; 

for male mice, no evidence of carcinogenic activity; 

and for female mice, equivocaTevidence of carcinogenic activity. Dr. Goldsworthy seconded the 

motion, which was accepted unanimously with seven 

votes. 
14 Nickel Oxide, NTP TR 451 
15 

INTRODUCTION 

NiO 

NICKEL OXIDE 

CAS No. 1313-99-1 

Chemical Formula: NiO Molecular Weight: 74.71 

Synonyms: Bunsenite; C.I. 77777; green nickel oxide; mononickel oxide; nickel monoxide; nickel oxide sinter 75; nickel protoxide; 

nickel (II) oxide; nickel (T+) oxide; nickelous oxide 

CHEMICAL AND PHYSICAL PROPERTIES 

Nickel oxide (high temperature green nickel oxide, 

oxidized at 870o-900 ° C and heated to 1,350 ° C; 

Boldt, 1967) is an olive gray powder with a melting 

point of 2,090 ° C and a density of 7.45 g/cm 3. It is 

insoluble in water and soluble in acids (USEPA, 

1986; Merck Index, 1989). The mean values for the 

mass median aerodynamic diameter at each exposure 

concentration of nickel oxide used in these 2-year 

studies ranged from 2.2 to 2.6/zm. The nickel oxide 

used in these studies is only one form of nickel oxide 

within a larger family of "oxidic" nickels. 

PRODUCTION, USE, 

AND HUMAN EXPOSURE 

Nickel was first isolated in 1751 and is found 

primarily as an oxide (laterite) or sulfide ore 

(pentlandite) (NIOSH, 1977; Warner, 1984; U.S. 

Bureau of Mines, 1984, 1985a). In 1991, the six 

largest nickel producing countries were the Soviet 

Union, Canada, Australia, New Caledonia, 

Indonesia, and Cuba. Approximately 55% of the 

nickel currently used is extracted from sulfide ore, 

and the remainder is extracted from oxide ore. The 

total annual world production of nickel is estimated 

at 1,000,000 tons (900,000 metric tons) (U.S. Bureau 

of Mines, 1991). 

The United States consumption of nickel is approximately 200,000 tons (180,000 metric tons) annually 

(U.S. Bureau of Mines, 1991). The United States 

consumes unwrought nickel (68 %), ferronickel 

( 17.3 %), nickel oxide ( 11.4 %), nickel salts ( 1.2 % ), 

and other forms (2.1%) (U.S. Bureau of Mines, 

1984, 1985b). The National Occupational Exposure 

Survey reported that 56,843 United States workers 

are potentially exposed to nickel sulfate and 

18,165 to nickel oxide (NIOSH, 1991). 

Half of the nickel sold each year is used to make 

stainless steel (Warner, 1984), which contains up to 

8 % nickel. The ability of nickel to impart corrosion 

resistance and strength leads to its wide use in 

chemicals and allied products and in petroleum 

refining, electrical equipment and supplies, aircraft 

and parts, construction, fabricated metal products, 

household appliances, machinery, and ships and boats 

(U.S. Bureau of Mines, 1984). 

Nickel constitutes about 0.008% of the earth's crust. 

Low levels of nickel are found in air, soil, water, 

food, and household objects. The average concentration of nickel in finished drinking water is less 

than 10 ppb. Nickel concentration in United States 

air has been found to range from 1 to 86 ng/m 3. The 

most probable nickel species present in the 

atmosphere include complex nickel, nickel oxide, and 

nickel sulfate, and the most probable species found in 
16 Nickel Oxide, NTP TR 451 

water include hydrated nickels (ATSDR, 1992). The 

average amount of nickel in mainstream particulate 

fractions of cigarette smoke is 79 ng/cigarette (Bache 

et al., 1985). Dietary intake of nickel per person 

from foods is estimated at 170 #g per day; intake 

from inhalation is estimated at 0.1 to 1 #g nickel per 

day (excluding cigarette smoke), and intake from 

drinking water is estimated at 2/~g per day (ATSDR, 

1992).. Nickel is listed as a frequently occurring 

chemical in waste disposal sites in the United States 

(Fed. Regist., 1987). 

The threshold limit values adopted by the American 

Conference of Governmental Industrial Hygienists 

(ACGIH) are 1 mg/m 3 for nickel metal and waterinsoluble salts and 0.1 mg/m 3 for water-soluble salts, 

but the ACGIH published notice of an intended 

change to 0.05 mg nickel/m 3 for water-soluble and 

water-insoluble nickel compounds (ACGIH, 1993). 

The National Institute for Occupational Safety and 

Health (NIOSH) recommended that the permissible 

exposure limit for nickel be reduced to 0.015 mg 

nickel/m 3 averaged over a work shift of up to 

10 hours per day, 40 hours per week (NIOSH, 

1977). 

Atomic absorption spectroscopy is a widely used 

method for quantifying nickel in the environment and 

in the workplace. This method of analysis measures 

total nickel without discerning the forms of nickel 

present, and most studies of environmental or industrial exposure report total nickel and not the occurrence of individual nickel species (ATSDR, 1992). 

ABSORPTION, DISTRIBUTION, 

AND EXCRETION 

Experimental Animals 

Animal model systems have been used to obtain 

information on the absorption, distribution, and 

excretion of nickel after inhalation exposure (watersoluble and water-insoluble forms of nickel), oral 

exposure (water-soluble forms of nickel), and dermal 

exposure (water-soluble forms of nickel). 

Intratracheal administration of nickel compounds was 

one method used by several investigators to study the 

fate of specific forms of nickel in the lung. English 

et al. (1981) reported on a comparative toxicokinetic 

study after intratracheal administration of [63Ni]- 

labeled nickel chloride or nickel oxide (low 

temperature nickel oxide calcined at 250 ° C) in 

Wistar rats. Nickel, after nickel chloride 

administration, was excreted primarily in the urine. 

After nickel oxide administration, nickel was equally 

excreted in the feces and urine. Nickel oxide 

persisted in the lung for more than 90 days, while 

nickel chloride was rapidly excreted from the lung 

with greater than 50 % of the nickel cleared from the 

lungs within 3 days. 

Nickel chloride administered as an intratracheal dose 

to Sprague-Dawley rats was excreted primarily in the 

urine. By day 3, 90 % of the instilled chemical was 

eliminated from the lungs. The lungs retained 29% 

of their initial burden at day 1, and this decreased to 

0.1% on day 21; 96 % of the chemical was excreted 

in the urine (Carvalho and Ziemer, 1982). 

The pulmonary clearance of intratracheally administered nickel subsulfide (Ni3S2) in mice has two 

distinct components with initial and final biological 

half-lives corresponding to 1.2 and 12.4 days, 

respectively. The excretion of the chemical 

(measured as 63Ni) was 60% in the urine and 40% in 

the feces; 57 % of the administered dose was excreted 

after 3 days with 33% appearing in the urine 

(Valentine and Fisher, 1984). In another experiment, 

the calculated clearance times of nickel subsulfide 

administered intratracheally to mice was also biphasic 

with a clearance half-life of 2 hours for the first 

phase and 119 hours for the second phase (Finch 

et al., 1987). 

In F344/N rats administered [63Ni]-labeled nickel 

oxide (high temperature, green oxide) or nickel 

subsulfide by pernasal inhalation, the lung half-life 

was estimated at 120 days for nickel oxide and 

5 days for nickel subsulfide (Benson et al., 1994). 

Following nickel oxide exposure, nickel was not 

distributed to the extrarespiratory tract tissue, and the 

material was only excreted in the feces during the 

first few days after exposure. In contrast, after 

nickel subsulfide exposure, nickel was detected in 

extrarespiratory tract tissue including blood and 

kidney, and nickel was excreted in the urine and the 

feces. The half-life of [63Nil-labeled nickel sulfate 

administered to F344/N rats intratracheally was 1 to 

3 days, nickel was present in extrarespiratory tract 

tissues (including blood, kidney, and intestine), and 

urine was the major route for excretion of nickel 

(Medinsky et al., 1987). 

Other studies also indicated that nickel oxide has a 

relatively long half-life in the rodent lung. Nickel 
Introduction 17 

oxide (formed at 550 ° C; mass median aerodynamic 

diameter [MMAD] of 0.15 #m, geometric standard 

deviation [~rg] of 1.5) given as an aerosol of 

750/zg/m 3 to Wistar rats had a bronchial clearance 

half-life of 1 day and an alveolar clearance half-life 

of 36 days (Hochrainer et al., 1980). Hochrainer 

et al. (1980) estimated that with continuous exposure 

to nickel oxide, a steady state would be reached after 

1 year. 

In Wistar rats after exposure to 0.6 or 8.0 mg nickel 

oxide/m 3 (high temperature, green oxide; MMAD of 

1.2 #m, trg of 2.5) for 6 to 7 hours per day for 1 to 

2 months, the lung clearance was estimated to be 

i00/zg per year. There was no apparent deposition 

of nickel in the liver, kidney, spleen, heart, brain, or 

blood (Kodama et al., 1985). Lung clearance halflives for nickel oxide (high temperature, green oxide) 

in Wistar rats exposed for 1 month were estimated to 

be 8, 11, and 21 months for nickel oxide with 

particulate MMADs of 0.6, 1.2, and 4.0 #m, 

respectively (Tanaka et al., 1985, 1988). 

In summary, in absorption and distribution studies for 

nickel administered intratracheally or by inhalation 

exposure, the lung half-life was 1 to 3 days for nickel 

sulfate, 5 days for nickel subsulfide, and greater than 

100 days for nickel oxide. Nickel was detected in 

extrarespiratory tract tissue after exposure to nickel 

sulfate or nickel subsulfide, but not after exposure to 

nickel oxide. 

The present studies also report findings on the 

deposition of nickel sulfate hexahydrate, nickel 

subsulfide, and nickel oxide in the lungs and tissues 

of rats and mice after 16 days, 13 weeks, and at 7 

and 15 months in the 2-year studies. These data 

show a relatively short half-life in the lung for nickel 

sulfate hexahydrate, a longer half-life for nickel 

subsulfide, and the longest half-life for nickel oxide 

(Benson et al., ~987; Dunnick et al., 1989). 

Studies of other routes of nickel exposure in rats, 

mice, and dogs indicate that 1% to 10% was 

absorbed after oral administration of nickel sulfate 

hexahydrate or nickel chloride, and less than 1% of 

nickel chloride was absorbed through the skin of 

guinea pigs within 24 hours (ATSDR, 1992; Nielsen 

et al., 1993). 

Humans 

In the industrial setting, a major route of nickel 

exposure in humans is by inhalation (Sunderman, 

1992); it is estimated that 35% of inhaled nickel is 

absorbed into the blood from the respiratory tract 

(Bennet, 1984; Grandjean, 1984; Sunderman and 

Oskarsson, 1991). Nickel .was excreted in the urine 

of nickel refinery workers for periods of up to 

6 months after facility closing, indicating that there 

are storage depots in the body that retain nickel for 

long periods of time (Morgan and Rouge, 1983). 

There were elevated nicke~t concentrations in 

specimens of urine, plasma, and nasal mucosa 

biopsies obtained from retired workers years after 

cessation of employment, although the specific form 

of nickel to which these workers were exposed was 

not identified (Torjussen and Andersen, 1979; 

Boysen et al., 1984). 

Andersen and Svenes (1989) found elevated levels of 

nickel in the lungs of nickel refinery workers, 

although workers who were diagnosed as having lung 

cancer had the same concentrations of nickel in the 

lung at autopsy as those who died of other types of 

cancer. In the workplace setting, exposure to nickel 

is monitored by analyzing urine, hair, or fingernails 

for levels of total nickel. 

When nickel sulfate was administered to fasting 

human volunteers, 27 % of the administered dose was 

absorbed when given in drinking water, while only 

0.7% was absorbed when administered in food. The 

elimination half-life for absorbed nickel averaged 

28 hours; 100% of the absorbed nickel was eliminated in either the feces or urine within 4 days 

(Sunderman, 1989, 1992). In studies in humans, 

reported absorption of radioactive nickel applied to 

occluded skin varied from 55% to 77% for nickel 

sulfate to 3% for nickel chloride (ATSDR, 1992). 

TOXICITY 

Studies of nickel toxicity after experimental or 

industrial exposure have been summarized in various 

reviews (NAS, 1975; IARC, 1976, 1984, 1987, 

1990; NIOSH, 1977; Brown and Sunderman, 1985; 

USEPA, 1986; European Chemical Industry, 1989; 

WHO, 1991; ATSDR, 1992; Nieboer and Nriagu, 

1992). In experimental animals and in humans, the 

primary toxic response to nickel after inhalation 

occurred in the respiratory system. 
18 Nickel Oxide, NTP TR 451 

Information on the dissolution half-lives for nickel 

subsulfide and nickel oxide in water and rat serum 

have been reported. The calculated dissolution halflives (based on in vitro studies) for nickel subsulfide 

and nickel oxide in water are greater than 7 or 

i 1 years, respectively. In rat serum, the estimated 

dissolution half-life is 23 days for nickel subsulfide 

and greater than 11 years for nickel oxide 

(Sunderman et al., 1987). While nickel subsulfide 

and nickel oxide are both relatively insoluble in 

water, nickel subsulfide is more soluble than nickel 

oxide in biological fluids. Soluble nickel salts (nickel 

hydroxide) have been shown to be more soluble in 

human serum than nickel subsulfide (Kasprzak et al., 

1983). The comparative toxicity of nickel sulfate 

hexahydrate, nickel subsulfide, and nickel oxide 

parallels the solubility of the compounds in biological 

fluids. 

Experimental Animals 

The acute toxicity values for selected nickel compounds are summarized in Table 1. Nickel carbonyl 

[Ni(CO)4] is the most acutely toxic form of nickel, 

but the use or formation of this nickel compound in 

manufacturing processes is limited (NAS, 1975). 

Exposure to nickel oxide, nickel sulfate hexahydrate, 

or nickel subsulfide is more common in the work, 

place. 

TABLE 1 

Toxicity Values for Nickel Carbonyl, Nickel Oxide, Nickel Sulfate Hexahydrate, Nickel Sulfate, 

and Nickel Subsulfide a 

Nickel Compound Species Route Toxicity Value b 

Nickel carbonyl Rat Inhalation 35 ppm (LC~o) 

Subcutaneous 63 mg/kg (LD~o) 

Intravenous 66 mg/kg (LD~3 

Intraperitoneal 39 mg/kg (LDso) 

Mouse Inhalation 67 mg/m 3 (LC~o) 

Dog Inhalation 360 ppm (LCLo) 

Cat Inhalation 1,890 mg/m 3 (LCu~) 

Rabbit Inhalation 73 g/m ~ (LCLo) 

Nickel oxide Rat 

Nickel sulfate hexahydrate 

(continued) 

Mouse 

Subcutaneous 25 mg/kg (LD~o) 

Intramuscular 180 mg/kg (TDLo) 

Intratracheal 90 mg/kg (TDLo) 

Subcutaneous 50 mg/kg (LD~o) 

Intraperitoneal 400 mg/kg (TDLo) 

Rabbit Subcutaneous 500 mg/kg (LDLo) 

Intravenous 36 mg/kg (LDLo) 

Guinea pig Subcutaneous 62 mg/kg (LDLo) 

Cat Subcutaneous 500 mg/kg (LDLo) 

Intravenous 72 mg/kg (LDLo) 

Dog Subcutaneous 500 mg/kg (LDLo) 

Intravenous 89 mg/kg (LDLo) 
Introduction 19 

TABLE 1 

Toxicity Values for Nickel Carbonyl, Nickel Oxide, Nickel Sulfate Hexahydrate, Nickel Sulfate, 

and Nickel Subsulfide (continued) 

Nickel Compound Species Route Toxicity Value b 

Nickel sulfate Rat Intraperitoneal 500 mg/kg (LD~o) 

Mouse Intraperitoneal 21 mg/kg (LD~) 

Intravenous 7 mg/kg (LDLo) 

Dog Subcutaneous 38 mg/kg (LDLo) 

Intravenous 38 mg/kg (LDLo) 

Cat Subcutaneous 24 mg/kg (LDLo) 

Rabbit Subcutaneous 33 mg/kg (LDLo) 

Intravenous 33 mg/kg (LDLo) 

Nickel subsulfide Rat Inhalation 1 mg/kg (TCLo) 

Subcutaneous 125 mg/kg (TDLo) 

Intra4enous 10 mg/kg (TDLo) 

Intramuscular 20 mg/kg (TDLo) 

Mouse Intramuscular 200 mg/kg (TDLo) 

a From RTECS (1987) 

b LC~o = median lethal concentration; LCLo = lowest lethal concentration; LD~o 

TCLo = lowest toxic concentration; TDLo = lowest toxic dose. 

= median lethal dose; LDLo = lowest lethal dose; 

In animals, after inhalation exposure to water-soluble 

and water-insoluble nickel compounds, the primary 

toxic response is seen in the respiratory system. 

Changes in a variety of parameters, including doserelated reduction in body weight, reduced leukocyte 

count, increased urine alkaline phosphatase, and 

increased erythrocyte count, were observed in Wistar 

rats continuously exposed to nickel oxide at 200, 

400, or 800 tzg/m 3 for 120 days (except for daily 

cleaning and feeding periods) (Weischer et al., 

1980). 

Alveolar macrophages from lung lavage fluid from 

rats exposed to nickel oxide at 120/zg/m 3 for 

12 hours per day, 6 days per week, for 28 days or by 

intratracheal injection (10 mg nickel oxide/mL) were 

examined by electron microscopy. Compared to 

controls, alveolar macrophages from exposed animals 

were increased in number and enlarged. In the 

cytoplasm of alveolar macrophages, phagosomes 

contained osmophilic nickel oxide particles as well as 

membranous and lamellar structures consistent with 

accumulation of phospholipid material (Migally 

et al., 1982; Murthy and Niklowitz, 1983). 

Respiratory toxicity to F344/Crl rats administered a 

single dose of either nickel subsulfide, nickel 

chloride, nickel sulfate, or nickel oxide by intratracheal instillation was evaluated by examining 

treatment-related changes in lung lavage fluid 

(Benson et al., 1986). No significant changes in lung 

lavage fluid were seen after exposure to nickel oxide. 

After exposure to nickel subsulfide, nickel sulfate 

hexahydrate, and nickel chloride, there were 

increases in the following parameters in lung lavage 

fluid: lactate dehydrogenase, /3-glucuronidase, total 

protein, glutathione reductase, glutathione peroxidase, and sialic acid. This evaluation was continued by exposing rats or mice to nickel oxide, 

nickel sulfate hexahydrate, or nickel subsulfide for 

13 weeks and looking for treatment-related markers 

of lung toxicity in lung lavage fluid (Benson et al., 

1989). Increases in /3-glucuronidase, total protein, 

neutrophil number, and macrophage number were 

observed in the lavage fluid after exposure of rats 
20 Nickel Oxide, NTP TR 451 

and mice to all three nickel compounds, although 

there were quantitative differences in the magnitude 

of the response, Inflammation was observed 

histologically in the lung of rats and mice exposed to 

the three nickel compounds. The severity of lung 

toxicity as measured by the changes in lung lavage 

fluid paralleled the severity of histologic changes in 

the lung. Nickel sulfate hexahydrate was the toxic, 

and nickel oxide was the least toxic (Benson et al., 

1989). 

Treatment of rats and mice with water-soluble and 

water-insoluble nickel salts may cause an alteration of 

local and systemic immunity, and this toxicity has 

been studied under various conditions and experiments (Table 2). 

TABLE 2 

Studies on the Immunologic Effects of Nickel Compounds 

Nickel Compound Species/Route Treatment Response Reference 

Cell-Mediated Immunity 

Nickel chloride CBA/J mice/ Single injection, Reduced T-lymphocyte Smialowicz et al. 

intramuscular 18 mg/kg proliferation (1984) 

Guinea pig In vitro study Inhibited macrophage migration Hennighausen and 

on spleen cells Lange (1980) 

Nickel sulfate B6C3Ft mice Up to 4,000 mg/kg/day 

(female)/oral for 23 weeks 

Depressed spleen lymphoproliferative Dieter et al. (1988) 

response to LPS (no effect on NK 

activity; PFC assay; mitogen response 

in spleen cells; resistance to 

Listeria challenge) 

Nickel subsulfide Cynomolgus Intratracheal 

monkey instillation 

0.06 #mol/g lung 

Humoral Immunity 

Nickel chloride CBA/J mice/ Single injection, 

intramuscular 18 mg/kg 

C57BL/6J mouse In vitro exposure 

spleen cells to nickel chloride 

Swiss albino mice/ 

intramuscular 

Swiss mice/ 

inhalation 

Nickel acetate Sprague-Dawley 

rats/intraperitoneal 

Nickel oxide Wistar rats/ 

inhalation 

(continued) 

3-12 #g Ni/kg body 

weight followed by 

immunization with 

sheep red blood cells 

2-hour inhalation 

exposure at 250/~g/m 3 

11 mg/kg body weight 

immunized with E. coli 

bacteriophage 

25-800/zg/m 3 for 

4 weeks to 4 months 

No effect on antibody-forming 

cells (in lung) 

Reduced antibody response to T-cell 

dependent sheep red blood cells 

Decreased response 

Depressed antibody formation 

Depressed antibody response 

to sheep red blood cells 

Haley et al. (1987) 

Smialowicz et al. 

(1984) 

Lawrence (1981) 

Graham et al. (1975a) 

Graham et al. (1978) 

Depressed circulating Figoni and Treagan 

antibody response (1975) 

Decreased ability to form spleen 

antibodies to sheep red blood cells 

Spiegelberg et al. 

(1984) 
Introduction 21 

TABLE 2 

Studies on the Immunologic Effects of Nickel Compounds (continued) 

Nickel Compound Species/Route Treatment Response Reference 

Macrophage Function 

Nickel chloride CBA/J mice/ Single injection, No effect on phagocytic capacity Smialowicz et al. 

intramuscular 18 mg/kg of peritoneal macrophages (1984) 

Rabbits Alveolar macrophage Reduced viability of macrophages Graham et al. (1975b) 

in vitro exposure 

Nickel oxide and Wistar rats/ 12 hours/day, 

nickel chloride inhalation 6 days/week for 

2 weeks at 0.1 mg/m 3 

Increased number of alveolar 

macrophages after nickel oxide; 

no change after nickel chloride 

Binghamaal. (1972) 

Nickel oxide Wistar rats/ 800/zg/m 3 for 2 weeks Decrease in alveolar macrophage Spiegelberg et al. 

inhalation phagocytic ability (1984) 

Nickel subsulfide Cynomolgus Intratracheal 

monkey instillation 

0.06/~mol/g lung 

Natural Killer Cell Activity 

Nickel chloride CBA/J and 

C57BL/6J mice/ 

intramuscular 

Lung macrophage activity decreased Haley et al. (1987) 

Host Resistance 

Nickel chloride and 

nickel oxide 

Single injection, Depressed NK activity (against Smialowicz et al. 

18 mg/kg Yac-1 murine lymphoma cells) (1984, 1985, 1986) 

Enhanced respiratory infection to 

Streptococcus 

CD mice and 

Sprague-Dawley rats/ 

inhalation 

0.5 mg/m 3 for 2 hours Adkins et al. (1979) 
22 Nickel Oxide, NTP TR 451 

Toxic responses to the immune system were 

measured in B6C3Ft mice after inhalation exposure 

to nickel subsulfide, nickel oxide, or nickel sulfate 

hexahydrate for 6 hours per day and 5 days per week 

for 13 weeks. Exposure concentrations were 0.11, 

0.45, and 1.8 mg nickel/m 3 for nickel subsulfide; 

0.47, 2.0, and 7.9 mg nickel/m 3 for nickel oxide; and 

0.027, 0.11, and 0.45 mg nickel/m ~ for nickel sulfate 

hexahydrate. Thymic weights in mice exposed to 

1.8 mg nickel/m 3 of nickel subsulfide were lower 

than those of the controls. Lung-associated lymph 

nodes were increased in size after exposure to all 

compounds. The number of alveolar macrophages in 

lavage samples was increased in mice exposed to the 

highest concentrations of nickel sulfate hexahydrate 

and nickel oxide and to 0.45 and 1.8 mg nickel/m 3 

nickel subsulfide. Numbers of antibody-forming cells 

in lung-associated lymph nodes of mice exposed to 

2.0 and 7.9 mg nickel/m 3 nickel oxide and 

1.8 mg nickel/m 3 nickel subsulfide were greater than 

those in the controls. Low numbers of antibodyforming cells were observed in the spleens of mice 

exposed to nickel oxide and in mice exposed to 

1.8 mg nickel/m 3 nickel subsulfide. Only mice 

exposed to 1.8 mg nickel/m 3 nickel subsulfide had a 

low mixed lymphocyte response. All concentrations 

of nickel oxide resulted in low levels of alveolar 

macrophage phagocytic activity, as did 0.45 and 

1.8 mg nickel/m 3 nickel subsulfide. None of the 

nickel compounds affected the phagocytic activity of 

peritoneal macrophages. 

Only 1.8 mg nickel/m 3 nickel subsulfide caused a 

depressed natural killer cell activity in the spleen. 

Results indicate that inhalation exposure of mice to 

nickel can have varying effects on the" immune 

system, depending on dose and physicochemical form 

of the nickel compound, and these effects were " 

observed at occupationally relevant exposure concentrations (Haley et al., 1990). 

Administration of nickel sulfate in the drinking water 

for 180 days (1 to 10 g/L drinking water, estimated 

to deliver 116 to 396 mg/kg body weight) resulted in 

a depressed proliferating response in the bone 

marrow and spleen of B6C3F1 mice (Dieter et al., 

1988). 

While experimental studies in animals show the 

potential of nickel to affect the immune system, the 

clinical significance of these studies in humans has 

not been determined (Nicklin and Nielsen, 1992). 

Further, there are no studies to examine if there is a 

relationship between effects on the immune system 

and the carcinogenic effects of nickel. 

Humans 

Most of the toxicity information on nickel and nickel 

compounds came from studies of workers in nickel 

refineries where the primary toxicity is to the respiratory system. In the industrial setting, nickel 

exposures were occasionally associated with rhinitis, 

sinusitis, and nasal-septal perforations. 

Hypersensitive allergic asthmatic reactions to nickel 

are rare (Nemery, 1990). There were also reports of 

pulmonary fibrosis in workers inhaling nickel dust 

(WHO, 1991). While respiratory toxicity has been 

observed in workers exposed to nickel in the 

industrial setting, these workers are often exposed to 

other toxic metals and/or cigarette smoke, and it has 

not always been possible to conclude that nickel is 

the sole causative agent of toxicity (ATSDR, 1992). 

Muir et al. (1993) reviewed X-rays of 745 former 

sinter workers and found no evidence of significant 

inflammatory or fibrogenic responses in the lungs of 

the exposed workers. 

Nickel contact hypersensitivity has been seen in the 

general population and in exposed workers. In the 

general population, contact sensitivity to nickelcontaining jewelry and/or prosthesis is another form 

of nickel toxicity (ATSDR, 1992). Other toxic 

reactions to nickel were reported in humans in 

isolated cases where exposures to nickel were not 

well characterized. These reactions included 

cardiovascular effects in a child ingesting nickel 

sulfate and gastrointestinal effects, transient increases 

in blood reticulocytes, or muscular pain in workers 

exposed to nickel-contaminated water (ATSDR, 

1992). In epidemiologic studies that have shown an 

association between nickel exposure and cancer, 

excess mortality from non-malignant respiratory 

effects or other diseases has not been observed (Doll 

et al., 1990). 
Introduction 23 

CARCINOGENICITY 

Experimental Animals 

The International Agency for Research on Cancer 

(IARC, 1990) summarized the results of experimental 

studies on the carcinogenic potential of nickel 

compounds after local injection (e.g., subcutaneous 

or intramuscular injection). Nickel oxide, nickel 

subsulfide, nickel carbonyl, and nickel powder cause 

neoplasms at the injection site, while the soluble 

nickel salts such as nickel sulfate have generally not 

been associated with a carcinogenic response at the 

injection site. A portion of the IARC (1990) listing 

and tabulation of over 100 experiments on the 

carcinogenic potential of nickel compounds is 

presented in Table 3. 

Information on the carcinogenic potential of nickel 

oxide, nickel subsulfide, and nickel sulfate hexahydrate by inhalation exposure is limited. Ottolenghi 

et al. (1975) reported that nickel subsulfide (70% of 

particles were smaller than 1 /zm in diameter; 25 % of 

particles were between 1 and 1.5/zm) caused an 

increased incidence in lung tumors in F344/N rats 

exposed to 1 mg/m 3 by inhalation (6 hours/day and 

5 days/week for 108 weeks). In the exposed groups, 

12% to 14% of the 208 animals examined had lung 

tumors compared to less than 0.5 % of 215 control 

animals. At the end of the 108-week exposure 

period, fewer than 5 % of the animals in exposed 

groups were alive compared with a survival of 31% 

in control groups. 

Other experimental studies indicated carcinogenic 

potential of nickel subsulfide for the respiratory tract 

mucosa. Yarita and Nettesheim (1978) reported that 

a single intratracheal dose of 1 or 3 mg nickel 

subsulfide/kg caused tumors in heterotrophic tracheal 

transplants in female F344 rats. These authors noted 

that toxicity might decrease a carcinogenic response 

resulting in a misleadingly low carcinoma incidence, 

based on the finding that the more toxic dose 

(3 mg/kg) caused only a 1.5 % incidence of carcinomas (there was a high incidence of tracheal hyperplastic change) versus a 10% carcinoma incidence in 

the 1 mg/kg group (generally with only a low 

incidence of toxic lesions). 

Hamsters exposed to 53 mg nickel oxide/m 3 (median 

diameter of 0.3/zm; geometric standard deviation of 

2.2) for 2 years did not have an increase in the 

incidence of lung tumors (Wehner et al., 1975). The 

hamster may be less sensitive than the rat to the 

carcinogenic effects of nickel (Furst and Schlauder, 

1971). 

Sunderman et al. (1959) found a low incidence of 

lung tumors in groups of Wistar rats exposed to 

nickel carbonyl (0.03 to 0.25 mg/m 3 for 30 minutes 

3 times/week for 1 year). Follow-up studies also 

showed a low incidence of lung tumors in rats 

exposed to nickel carbonyl (Sunderman and 

Donnelly, 1965). 

Information on the carcinogenic potential of nickel 

after oral administration is limited (IARC, 1990). 

Lifetime .exposure to nickel acetate at low concentrations (5 ppm) induced no lung lesions in Swiss 

mice (Schroeder etal., 1964; Schroeder and 

Mitchener, 1975); the maximum tolerated dose was 

not reached. Ambrose et al. (1976) administered 

nickel sulfate hexahydrate in the diet of W.istar rats 

or dogs (0, 100, 1,000, 2,500 ppm) for 2 years, and 

no treatment-related lesions were observed. 

Humans 

Exposure to nickel in the workplace has been 

associated with an increase in lung and nasal sinus 

tumors (IARC, 1976, 1987, 1990; Doll et al., 1990). 

Based on the finding of lung and/or nasal sinus 

tumors in nickel refinery workers, IARC classified 

nickel and nickel compounds as human carcinogens 

(Group 1), although there was insufficient information available to evaluate the carcinogenic risk for 

individual nickel compounds or the risk for cancer 

based on exposure to different concentrations of 

nickel compound(s) (IARC, 1987). 

Information on the hazards associated with exposure 

to nickel came from studies on occupational exposure 

in nickel refineries in Clydach, South Wales; 

Kristiansand, Norway; the International Nickel 

Company (INCO) refineries in Ontario, Canada; or 

from other studies of nickel refineries, nickel mines, 

or other nickel industrial operations throughout the 

world (Doll, 1984). 
24 Nickel Oxide, NTP TR 451 

TABLE 3 

Summary of Studies Used to Evaluate. the Carcinogenicity of Nickel Compounds 

in Experimental Animals a 

Nickel Compound Species/Route Lesion Incidence b Reference 

Nickel oxides and hydroxides 

Nickel monoxide 

(green) 

Nickel monoxide 

Nickel monoxide 

(green) 

Nickel monoxide 

Nickel hydroxide 

Nickel trioxide 

(continued) 

Rat/inhalation 

Rat/inhalation 

Rat/intrapleural 

Rat/intratracheal 

Rat/intramuscular 

Rat/intramuscular 

Rat/intramuscular 

Rat/intramuscular 

Rat/intramuscular 

Rat/subperiosteal 

Rat/intraperitoneal 

Rat/intraperitoneal 

Rat/intrarenal 

Mouse/intramuscular 

Hamster/inhalation 

Hamster/intratracheal 

Rat/intramuscular 

Rat/intramuscular 

Rat/intramuscular 

Rat/intracerebral 

0.6 mg/m3:0/6 lung lesion 

8 mg/mS: 1/8 lung lesion 

0.06 mg/m3:0/40 lesion 

0.2 mg/mS: 0/20 lesion 

Controls: 0/32 local lesions 

31/32 local lesions 

Controls: 0/40 lesions 

10 × 5 mg: 10/37 lung lesions 

10 × 15 mg: 12/38 lung lesions 

21/32 local lesions 

2/20 local lesions 

0/20 local lesions 

14/15 local lesions 

0/20 local lesions 

0/20 local lesions 

46/47 local lesions 

25 nag: 12/34 local lesions 

100 mg: 15/36 local lesions 

0/12 local lesions 

33/50 and 23/52 local lesions 

1/51 osteosarcoma 

Controls: 4/50 lung lesions 

1/49 lung lesions 

15/20 local lesions 

Dried gel: 5/19 local lesions 

Crystalline: 3/20 local lesions 

Colloidal: 0/13 local lesions 

0/10 local lesions 

3/20 local lesions 

Horie et al. (1985) 

Glaser et al. (1986) 

Skaug et al. (1985) 

Pott et al. (1987) 

Gilman (1962). 

Gilman (1966) 

Sosifiski (1975) 

Sunderman and McCully (1983) 

Berry et al. (1984) 

Berry et al. (1984) 

Pott et al. (1987) 

Pott et al. (1989, 1992) 

Sunderman et al. (1984) 

Gilman (1962) 

Wehner et al. (1975, 1979) 

Farrell and Davis (1974) 

Gilman (1966) 

Kasprzak et al. (1983) 

Judde et al. (1987) 

Sosifiski (1975) 
Introduction 25 

TABLE 3 

Summary of Studies Used to Evaluate the Carcinogenicity of Nickel Compounds 

in Experimental Animals (continued) 

Nickel Compound Species/Route Lesion Incidence Reference 

Nickel sulfides 

Nickel disulfide 

Nickel sulfide 

(amorphous) 

f~-Nickel sulfide 

Nickel sulfide 

(amorphous) 

Nickel sulfide 

B-Nickel sulfide 

Nickel sulfide 

(amorphous) 

Nickel subsulfide 

(continued) 

Rat/intramuscular 

Rat/intrarenal 

Rat/intramuscular 

Rat/intramuscular 

Rat/intramuscular 

Rat/intrarenal 

Rat/intrarenal 

Rat/intrarenal 

Rat/inhalation 

Rat/intratracheal 

Rat/intrapleural 

Rat/subcutaneous 

Rat/subcutaneous 

Rat/intramuscular 

Rat/intramuscular 

12/14 local lesions 

2/10 local lesions 

5.6 rag: 0/10 local lesions 

22.4 mg: 0/10 local lesions 

14/14 local lesions 

3/25 local lesions 

0/18 local lesions 

8/14 local lesions 

0/15 local lesions 

14/208 malignant lung lesions 

15/208 benign lung lesions 

0.94 mg: 7/47 lung lesions 

1.88 mg: 13/45 lung lesions 

3.75 mg: 12/40 lung lesions 

28/32 local lesions 

3.3 rag: 37/39 local lesions 

10 mg: 37/40 local lesions 

18/19 local lesions 

25/28 local lesions 

Controls: 

1/19 local lesion 

10 mg powder: 

19/20 local lesions 

10 mg diffusion chamber: 

14/17 local lesions 

500 mg fragments: 

5/7 local lesions 

500 mg discs: 

14/17 local lesions 

Sunderman (1984) 

Sunderman et al. (1984) 

Sunderman and Maenza (1976) 

Sunderman (1984) 

Sunderman (1984) 

Jasmin and Riopelle (1976) 

Sunderman et al. (1984) 

Sunderman et al. (1984) 

Ottolenghi et al. (1975) 

Port et al. (1987) 

Skaug et al. (1985) 

Mason (1972) 

Shibata et al. (1989) 

Gilman (1962) 

Gilman and Herchen (1963) 
26 Nickel Oxide, NTP TR 451 

TABLE 3 

Summary of Studies Used to Evaluate the Carcinogenicity of Nickel Compounds 

in Experimental Animals (continued) 

Nickel Compound Species/Route Lesion Incidence Reference 

Nickel sulfides (continued) 

Nickel subsulfide 

(disc) 

Nickel subsulfide 

a-Nickel subsulfide 

Nickel subsulfide 

Rat/intramuscular 

Rat/intramuscular 

Rat/intramuscular 

Rat/intramuscular 

Rat/intramuscular 

Rat/intramuscular 

Rat/intramuscular 

Rat/intramuscular 

Rat/intramuscular 

Rat/intramuscular 

Rat/intramuscular 

Rat/intraperitoneal 

Rat/intraperitoneal 

Rat/intraperitoneal 

Rat/subperiosteal 

Rat/intrafemoral 

Rat/intrarenal 

Removal of disc after 64 days: 

4/10 local lesions 

Removal of disc after 128 days: 

7/10 local lesions 

Removal of disc after 206 days: 

10/10 local lesions 

NIH black: 28/28 local lesions 

Hooded: 14/23 local lesions 

3.3 mg: 38/39 local lesions 

10 mg: 34/40 local lesions 

5 mg: 8/20 local lesions 

20 mg: 9/9 local lesions 

Fischer: 59/63 local lesions 

Hooded: 11/20 local lesions 

0.6 mg: 7/30 local lesions 

1.2 mg: 23/30 local lesions 

2.5 mg: 28/30 local lesions 

5 mg: 29/30 local lesions 

0.63 mg: 7/29 local lesions 

20 mg: 9/9 local lesions 

9/9 local lesions 

10/20 local lesions 

2/100 local lesions 

19/20 local lesions 

9/37 local lesions 

27/42 local lesions 

6 mg: 20/36 local lesions 

12 mg: 25/35 local lesions 

25 mg: 25/34 local lesions 

0/20 local lesions 

10/20 local lesions 

In glycerin: 7/16 local lesions 

In saline: 11/24 local lesions 

Herchen and Gilman (1964) 

Daniel (1966) 

Mason (1972) 

Sunderman and Maenza (1976) 

Yamashiro et al. (1980) 

Sunderman et a/.(1976) 

Sunderman (1981 ) 

Sunderman (1984) 

Berry et al. (1984) 

Judde et al. (1987) 

Shibata et al. (1989) 

Gilman (1966) 

Pott et al. (1987) 

Pott et al. (1989, 1992) 

Berry et al. (1984) 

Berry et al. (1984) 

Jasmin and Riopelle (1976) 

(continued) 
Introduction 27 

TABLE 3 

Summary of Studies Used to Evaluate the Carcinogenicity of Nickel Compounds 

in Experimental Animals (continued) 

Nickel Compound Species/Route Lesion Incidence Reference 

Nickel sulfides (continued) 

a-Nickel subsulfide 

Nickel subsulfide 

or-Nickel subsulfide 

Nickel subsulfide 

ct-Nickel subsulfide 

Nickel subsulfide 

(continued) 

Rat/intrarenal 

Rat/intratesticular 

Rat/intraocular 

Rat/transplacental 

Rat/pellet implantation 

into subcutaneous implanted 

tracheal grafts 

Rat/intra-articular 

Rat/intra-fat 

Mouse/intratracheal 

Mouse/subcutaneous 

Mouse/intramuscular 

Mouse/intramuscular 

Mouse/intramuscular 

Hamster/intratracheal 

Hamster/intramuscular 

Hamster/topical 

Rabbit/intramuscular 

Wistar Lewis: 7/11 local lesions 

NIH black: 6/12 local lesions 

Fischer 344:9/32 local lesions 

Long-Evans: 0/12 local lesions 

16/19 local lesions 

14/15 local lesions 

No difference in lesion 

incidence 

5 mg: 9/60 local lesions 

15 rag: 45/64 local lesions 

16/19 local lesions 

9/20 local lesions 

No increase in lung 

lesion incidence 

5 mg: 4/8 local lesions 

10 rag: 7/8 local lesions 

Swiss: 27/45 local lesions 

C3H: 9/18 local lesions 

5 mg: 4/8 local lesions 

10 rag: 4/8 local lesions 

C57B16:5/10 local lesions 

DBA/2:6/10 local lesions 

0/62 lung lesions 

Controls: 0/14 local lesions 

5 mg: 4/15 local lesions 

10 rag: 12/17 local lesions 

54 mg total: 0/6 local lesions 

108 mg total: 0/7 local lesions 

540 mg total: 0/15 local lesions 

1,080 mg total: 0/13 local lesions 

16 local lesions 

Sunderman et al. (1979) 

Damjanov et al. (1978) 

Albe~ et al. (1980); 

Sunderman (1983a) 

Sunderman et al. (1981) 

Yarita and Nettesheim (1978) 

Shibata et al. (1989) 

Shibata et al. (1989) 

Fisher et al. (1986) 

Oskarsson et al. (1979) 

Gilman (1962) 

Oskarsson et al. (1979) 

Sunderman (1983a) 

Muhleaa/. (1992) 

Sunderman (1983b) 

Sunderman (1983a) 

Hildebrand and Biserte (1979a,b) 
28 Nickel Oxide, NTP TR 451 

TABLE 3 

Summary of Studies Used to Evaluate the Carcinogenicity of Nickel Compounds 

in Experimental Animals (continued) 

Nickel Compound Species/Route Lesion Incidence Reference 

Nickel sulfides (continued) 

of-Nickel subsulfide 

Nickel subsulfide 

Nickel ferrosulfide 

Rabbit/intramuscular 

Salamander/intraocular 

Rat/intramuscular 

Rat/intrarenal 

0/4 local lesions 

7/8 local lesions 

15/15 local lesions 

1/12 local lesions 

Sunderma~ (1983b) 

Okamoto (1987) 

Sunderman (1984) 

Sunderman et al. (1984) 

Nickel salts 

Basic nickel carbonate 

tetrahydrate 

Nickel acetate 

Nickel acetate 

tetrahydrate 

Nickel ammonium 

sulfate 

Nickel carbonate 

Nickel chloride 

Nickel chloride 

hexahydrate 

Nickel chromate 

Nickel fluoride 

Nickel sulfate 

(continued) 

Rat/intraperitoneal 

Mouse/intraperitoneal 

Rat/intramuscular 

Mouse/intraperitoneal 

Rat/intraperitoneal 

Rat/intramuscular 

Rat/intramuscular 

Rat/intramuscular 

Rat/intraperitoneal 

Rat/intramuscular 

Rat/intramuscular 

Rat/intramuscular 

Rat/intramuscular 

Rat/intramuscular 

Controls: 1/33 lung lesions 

25 rag: 1/35 lung lesions 

50 mg: 3/33 lung lesions 

72 mg: 8/18 lung lesions 

180 mg: 7/14 lung lesions 

360 mg: 12/19 lung lesions 

1/35 local lesions 

Controls: 0.32 lung 

lesions/animal 

1.5 lung lesions/animal 

Controls: 1/33 lung lesions 

25 rag: 3/35 lung lesions 

50 mg: 5/31 lung lesions 

0/35 local lesions 

6/35 local lesions 

0•35 local lesions 

Controls: 1/33 lung lesions 

4/32 lung lesions 

1/16 local lesions 

3/18 local lesions 

1/35 local lesions 

0/20 local lesions 

0/20 local lesions 

Pott et al. (1989, 1992) 

Stoner etal. (1976) 

Payne (1964) 

Poirier a a/.(1984) 

Pott a al.(1989, 1992) 

Payne (1964) 

Payne (1964) 

Payne (1964) 

Pott et a/.(1989, 1992) 

Sunderman (1984) 

Gilman (1966) 

Payne (1964) 

Gilman (1966) 

Kasprzak et al. (1983) 
Introduction 29 

TAnLE 3 

Summary of Studies Used to Evaluate the Carcinogenicity of Nickel Compounds 

in Experimental Animals (continued) 

Nickel Compound Species/Route Lesion Incidence Reference 

Nickel salts (continued) 

Nickel sulfate 

hexahydrate 

Nickel sulfate 

heplahydrate 

Rat/intramuscular 0/32 local lesions Gilman (1962) 

Rat/intraperitoneal Controls: 1/33 lung lesions 

6•30 lung lesions 

Poa~al. (1989, 1992) 

Other 

Nickel carbonyl Rat/inhalation 

Rat/inhalation 

Raffintravenous 

30 mg/m ~ for 32 weeks: 

1/64 pulmonary lesions 

60 mg/m a for 32 weeks: 

1/32 pulmonary lesions 

250 mg/m ~ once: 

1/80 pulmonary lesion 

Controls: 0/32 lung lesions 

1/71 lung lesions 

19/120 lung lesions 

Sunderman et al. (1957, 1959) 

Sunderman and Donnelly (1965) 

Lau et al. (1972) 

a From IARC (1990) 

b Number of animals with lesion per effective number 

The United States Environmental Protection Agency 

(USEPA, 1986) and the International Committee on 

Nickel Carcinogenesis in Man (Doll et al., 1990) 

reviewed the epidemiological evidence for cancer 

after exposure to nickel in mining or refinery operations. A complete analysis on the type of ore mined 

and the calcining, smelting, and refining operations 

in 10 different mines or refineries throughout the 

world can be found in Doll et al. (1990) and in other 

more recent summaries (Courtin, 1994; McIlveen and 

Negusante, 1994; Nieboer and Templeton, 1994; 

Norseth, 1994). Doll et al. (1990) also estimate the 

type of nickel exposures encountered based on 

knowledge of the nickel process procedures used and 

a few relatively recent measurements of total airborne 

nickel. This study focused primarily on "high-risk" 

cohorts of nickel workers, and many of the workers 

studied did not have nickel-related cancers. 

The first indication that some form of nickel can give 

rise to lung and nasal sinus cancers was obtained 

from refinery workers at Clydach, South Wales 

(Bridge, 1933; Doll, 1958; Morgan, 1958). The 

Clydach Nickel Refinery (Mond Nickel Works) 

opened in 1902 and used a nickel-copper matte. In 

1933, nasal sinus and lung cancers were first noted 

in workers who were employed prior to 1925. After 

1925, the copper and sulfate content of the matte was 

reduced, the arsenic contamination in sulfuric acid 

used to extract copper was reduced, the use of 

respirators and masks was introduced, and improvements were made in factory design that reduced 

exposure to nickel (USEPA, 1986; Doll et al., 1990). 

An increased risk for lung and nasal sinus cancers 

was particularly noted in refinery work involving 

roasting, sintering, and calcining processes that 

converted impure nickel-copper matte to an oxide 

(Doll et al., 1990). 

Peto et al. (1984) analyzed the incidence of lung and 

nasal sinus cancers found in workers in the Clydach 

plant and found the highest incidence of cancer in 
30 Nickel Oxide, NTP TR 451 

those workers employed in the copper sulfate and 

furnace areas. There was no increased risk to 

workers in the reduction area where nickel carbonyl 

concentrations were highest. 

Other evidence for nasal sinus and lung cancer come 

from studies of workers in the INCO (Ontario, 

Canada) mines and refineries (Roberts etal., 

1989a,b; Muir et al., 1994). Facilities operated 

include the Sudbury area mines (Copper Cliff Smelter 

and the Port Colborne refinery) that use an ore that 

is primarily petlandite (NiFeS2). Men working in 

mining operations in Ontario had an increase in lung 

cancer risk, but no nasal sinus cancers (Doll et al., 

1990). 

The Falconbridge refinery in Kristiansand, Norway, 

receives nickel-copper matte from Canada and uses 

an electrolysis procgss to refine the ore. Workers in 

roasting and smelting operations are exposed to d~ 

dust containing nickel subsulfide and nickel oxide. 

Electrolysis workers are also exposed to nickel 

sulfate and nickel chloride. In this cohort, nasal 

sinus and lung cancer risks were increased in men 

working in the electrolysis department, thus implicating the soluble forms of nickel as the cause for the 

cancer (USEPA, 1986; Doll et al., 1990). The 

electrolysis workers had the highest average plasma 

and urine nickel concentrations (Hogetveit et al., 

1978). 

Enterline and Marsh (1982) studied cancer rates in 

workers at a refinery in Huntington, West Virginia, 

which received nickel-copper matte from Canada 

and/or nickel matte from New Caledonia. The Doll 

Committee reported no clear evidence for an 

increased incidence in lung cancer in this population, 

although the data from this cohort provided weak 

evidence for an increased incidence in lung cancer in 

men exposed to sulfidic nickel at 4 mg nickel/m 3 for 

more than a year (Doll et al., 1990). 

Results of epidemiology studies of workers in the 

nickel mining, smelting, and refinery operations in 

New Caledonia showed no increased incidence of 

lung or upper respiratory tract cancers (Goldberg 

et al., 1994). Nickel at this site is mined from nickel 

laterites including silicate and limonite ores. The 

Doll Committee also reported little evidence for an 

increased incidence in lung or upper respiratory tract 

cancer in this group of nickel workers (Doll et al., 

1990). 

The ten cohorts of nickel workers studied by the Doll 

Committee include the six cohorts mentioned above 

(nickel refinery operations, Clydach, South Wales; 

Falconbridge Nickel Mines, Ontario, Canada; INCO 

mines and refineries [Copper Cliff, Port Colborne, 

and Coniston], Ontario, Canada; Falconbridge 

refinery, Kristiansand, Norway; Huntington Alloys, 

West Virginia; and New Caledonia mines) as well as 

the Hanna Nickel Smelting Co., Oregon; Oak Ridge 

Gaseous Diffusion Plant, Tennessee; Outokumpu Oy 

nickel refinery, Finland; and Henry Wiggin Alloy 

Co., England (Doll et al., 1990). 

The results within the individual cohorts varied, but 

the overall conclusion by the Doll Committee suggested that more than one form of nickel gives rise to 

lung and nasal sinus cancer. Much of the respiratory 

cancer risk was attributed to exposure to a mixture of 

oxidic and sulfidic nickel. In the absence of sulfidic 

nickel, exposure to large concentrations of oxidic 

nickel was also associated with increased lung and 

nasal sinus cancer risks. There was evidence that 

exposure to soluble nickel salts increased the risk of 

lung and nasal sinus cancer and that it may enhance 

risks associated with exposure to less soluble forms 

of nickel. There was no evidence that metallic nickel 

was associated with increased lung and nasal sinus 

cancer risks. There was no evidence to suggest that 

exposure to metallic nickel or any of its compounds 

was likely to produce cancers elsewhere than in the 

lung or nose. These investigators were not able to 

provide exposure-specific estimates of risks for 

individual nickel species. However, the evidence 

from these studies suggests that respiratory cancer 

risks in "high-risk" cohorts are primarily related to 

exposure to water-soluble nickel compounds at 

concentrations in excess of i mg nickel/m 3 and to 

exposure to less soluble forms at concentrations 

greater than I0 mg nickel/m 3. 

There are no studies evaluating the potential carcinogenic effect in humans specifically after oral exposure to nickel (ATSDR, 1992). 

While nickel and nickel compounds are classified by 

the IARC as Group 1 (human) carcinogens, the 

mechanism for this carcinogenic activity is not fully 

understood (Sunderman, 1989; Costa, 1991; Snow, 

1992). The mechanisms involved in the indtiction of 

cancer by nickel compounds may be related to the 

ability of nickel ions to interact with chromatin 

proteins and/or the ability of nickel to generate 
Introduction 31 

intracellular oxidants (Costa et al., 1994). Recent 

studies suggest that nickel generates free radicals, 

and the subsequent oxidative reactions lead to DNA 

damage and cancer. Studies show that 1) incubation 

of nickel ions with cysteine under aerobic conditions 

generates hydroxyl radicals and carbon-centered alkyl 

radicals, suggesting free radicals are generated by 

nickel (II)-thiol complexes and molecular oxygen (Shi 

et al., 1993); 2) in forward mutation assays with 

bacterial DNA, nickel ions produce tandem double 

CC ~ TT mutations consistent with damage to DNA 

by either ultraviolet irradiation or oxygen-free 

radicals (Tkeshelashvili etal., 1993); and 3) in 

in vitro studies, nickel ions induce increases in 

8-hydroxy-2'-deoxyguanosine (8-OH-dG), a 

biomarker of oxidatively damaged DNA (Littlefield 

et al., 1991). 

After subcutaneous or intramuscular injection of 

nickel compounds, the water-insoluble nickel compounds are the most potent carcinogens. These 

findings may be related to the fact that waterinsoluble nickel compounds are more readily phagocytized than are the water-soluble nickel salts, which 

passively diffuse through the cell membrane. Phagocytized nickel particles are internalized in vacuoles 

whose acidity accelerates the dissolution of nickel 

ions and results in a higher concentration of nickel 

than would be achieved by the cellular uptake of 

water-soluble nickel salts (Costa et al., 1994). 

REPRODUCTIVE 

AND DEVELOPMENTAL TOXICITY 

Experimental Animals 

Leonard and Jacquet (1984) reviewed studies which 

show that water-soluble nickel compounds administered orally or by peritoneal routes have the potential to cause embryotoxicity in rodents. In these 

studies, the nickel compounds were generally administered at higher doses than humans would be 

exposed to in drinking water or in the diet. 

Studies in rodents have indicated that water-soluble 

nickel compounds can cross the placenta or be 

excreted in the milk of lactating animals. When 

[63Ni]-labeled nickel chloride was administered as an 

oral bolus dose (10/zmol or 0.58 mg/kg body 

weight) to pregnant mice, the label was detected in 

various fetal tissues including liver, kidney, lung, 

brain, and heart. In another experiment, when 

[63Ni]-labeled nickel chloride was injected into 

pregnant mice, nickel was found to cross the 

placenta, and a marked uptake of nickel was 

observed in the embryo as measured by whole-body 

autoradiography (Olsen and Jonsen, 1979). When 

nickel chloride hexahydrate was given as a single 

subcutaneous dose (10 to 100/zmol NiCI2" 6H20/kg 

body weight or 23 mg/kg) to lactating rats, nickel 

was excreted in the rnilk and was found in the plasma 

of the pups (Dostal et al., 1989). The doses used in 

these studies are higher than the average 

concentration of nickel found in drinking water in the 

United States (48/~g/L water) (NAS, 1975). 

Nickel chloride administered in the drinking water 

(50 and 250 ppm, estimated to deliver 7 or 31 mg/kg 

of nickel compound) to female rats for 11 weeks 

prior to mating and then during two successive 

gestation and lactation periods caused an increase in 

the proportion of dead pups per litter (Smith et al., 

1993). 

Other studies in rodents administered nickel chloride 

by intramuscular or intraperitoneal injection during 

gestation also showed developmental toxicity or fetal 

death. Nickel chloride injected intraperitoneally (1, 

2, or 4 mg/kg body weight) to pregnant Wistar 

Porton rats on day 8, 12, or 16 of pregnancy caused 

skeletal retardation (poor ossification), hydrocephalus, hydronephrosis, heart defects, and hemorrhage. At these doses, there was an increase in 

maternal plasma glucose concentration (Mas et al., 

1985). 

Nickel chloride injected intramuscularly (16 mg/kg) 

on day 8 of gestation to Fischer rats reduced the 

mean number of live pups per dam and diminished 

fetal body weights on day 20 (Sunderman et al., 

1978). Nickel chloride injected into chicken eggs at 

doses of 0.02 to 0.8 mg per egg on days 0, 1, 2, 3, 

and 4 after fertilization caused malformations in the 

embryo including exencephaly, everted viscera, 

abnormalities in the limb development, 

microphthalmia, and reduced body size when 

examined at day 8 (Gilani and Marano, 1980). 

Groups of pregnant hamsters were exposed to nickel 

carbonyl by inhalation (0.06 mg/L for 15 minutes) on 

days 4, 5, 6, 7, or 8 of gestation; dams were evaluated on day 15 of gestation. Teratogenic effects 

observed included cystic lung, exencephaly, cleft 

palate, and fused ribs. In another series of experiments where dams were allowed to deliver the pups, 
32 Nickel Oxide, NTP TR 451 

neonatal mortality was increased in the exposed 

groups (Sunderman et al., 1980). Nickel carbonyl 

administered to pregnant dams by intravenous 

injection (11 mg/kg) on day 7 of gestation caused an 

increase in fetal mortality, diminished body weight of 

live pups, and increased incidences of fetal 

abnormalities including anophthalmia, microphthalmia,, cystic lungs, and hydronephrosis 

(Sunderman et al., 1983). 

In a study of nickel oxide, Wistar rats were exposed 

to 1.6 mg nickel/m 3 by inhalation on gestation days 1 

through 20. There was no evidence of embryotoxicity (Weischer et al., 1980). 

These and other studies show that water-soluble 

nickel salts have the potential to cause embryotoxicity 

in rodents. The metal can cross the feto-maternal 

barrier and enter the fetus. The embryotoxicity of 

nickel may be related to several factors including the 

mutagenic properties of nickel, direct effects on the 

mammalian embryo, or indirect effects through 

maternal toxicity. Further work is needed to 

understand the mechanisms for these effects (Leonard 

and Jacquet, 1984). 

Humans 

Until recently, there have been few studies of reproductive effects in humans after exposure to nickel 

(ATSDR, 1992). A preliminary study of nickel 

refinery workers in Russia who were exposed to 

water-soluble nickel salts in electrolysis departments 

noted a suggested increased risk of pregnancy 

complications in female workers (Chashschin et al., 

1994). 

GENETIC TOXICITY 

Recent detailed reviews of the mutagenicity of nickel 

compounds and the possible mechanisms involved in 

the production of these effects were presented by 

Coogan et al. (1989), Christie and Katisifis (1990), 

Costa (1991), Snow (1992), and Costa et al. (1994). 

Nickel compounds are not typically detected as 

bacterial mutagens, but they often give positive 

results in in vitro assays designed to identify compounds that induce chromosomal damage in mammalian cells in the form of sister chromatid 

exchanges, chromosomal aberrations, and DNA 

strand breaks. Nickel salts have been shown to 

inhibit DNA replication and to increase replication 

errors in mammalian cells in vitro, possibly by 

competing with magnesium for essential binding sites 

on DNA polymerases (Christie et al., 1991). In 

addition, positive results were demonstrated in 

mammalian cell forward mutation assays (TK locus 

in mouse lymphoma cells and hypoxanthine phosphoribosyl .transferase locus in hamster V79 cells), 

although these responses are usually weak (Nishimura 

and Umeda, 1979; Amacher and Paillet, 1980; 

Morita et al., 1991; Lee et al., 1993). Insoluble 

crystalline nickel compounds are more active in 

genetic toxicity assays than the soluble or amorphous 

forms of nickel. Presumably, this differential activity 

derives from the more efficient entry of insoluble 

nickels into the cell through phagocytosis (Costa, 

1991), longer retention of these compounds within 

the cell, and the consequent higher intracellular 

concentration of nickel (II) ions. Soluble nickel salts 

cannot be efficiently phagocytized and do not 

accumulate in high concentration within the cell. 

Based on the results of cell transformation studies in 

cultured rodent cells, Costa and Heck (1983) 

concluded that the nickel sulfide compounds must be 

in the crystalline, rather than in the amorphous state 

to be efficiently phagocytized into the cell and cause 

genetic damage. Particle size (Costa and 

Mollenhauer, 1980) and surface charge (Costa et al., 

1982) are also important factors in the phagocytosis 

of nickel compounds. Insoluble nickel compounds, 

once inside the cell, aggregate near the nucleus 

(Bryan, 1981; Evans et al., 1982) where they are 

dissolved by lysosomes, releasing nickel (II) ions that 

proceed to effect DNA damage (Costa et al., 1994). 

The DNA damage resulting from nickel exposure has 

been attributed to one or more of the following 

mechanisms. It may follow the generation of 

short-lived reactive oxygen species inside the 

nucleus, produced by the oxidation of Ni ÷2 to Ni ÷3 

by hydrogen peroxide or other oxidants subsequent to 

the binding of nickel ions to ligands such as amino 

acids, glutathione, and amino acid side chains of 

nuclear proteins (Biggart and Costa, 1986; Inoue and 

Kawanishi, 1989; Nieboer etal., 1989; Cotelle 

et al., 1992; Tkeshelashvili et al., 1993; Sugiyama, 

1994). The formation of persistent DNA-protein 

crosslinks is implicated in the generation of 

nickel (II)-induced DNA damage (Ciccarelli and 

Wetterhahn, 1982; Lee et al., 1982; Patierno and 

Costa, 1985; Sen and Costa, 1986a). Factors 

involved in the binding of nickel ions to DNA, 

nuclear proteins, and other nuclear structures are 
Introduction 33 

reviewed by Coogan et al. (1989). The binding 

affinity of nickel to protein is far greater than to 

purified DNA (Eichorn and Shin, 1968) and 

therefore, the mutagenic activity of nickel (II) ions 

probably derives primarily from the binding of nickel 

to chromosomal protein rather than directly to DNA 

(Costa, 1991). Nickel binds preferentially to 

heterochromatic regions of the chromosomes such as 

the long arm of the X chromosome in cultured 

Chinese hamster cells (Sen and Costa, 1986a,b; Sen 

et al., 1987; Costa, 1991); binding of nickel ions to 

the long arm of the X chromosome and subsequent 

deletions in this region were postulated to cause the 

loss of a gene controlling senescence in cultured 

Chinese hamster cells and to promote immortality in 

transformed cultured Chinese hamster cell lines 

(Klein et al., 1991). A schematic representation of 

some of the proposed mechanisms of nickel-induced 

genotoxicity, based upon the current understanding of 

the activities of nickel ions within mammalian cells, 

is presented in Figure 1. The genetic toxicity data 

for each of the three nickel compounds under study 

by the NTP are described below. 

The mutagenicity data for nickel oxide are limited; 

however, there are clear indications of genotoxicity 

in some in vitro test systems. Although exposure to 

nickel Oxide did not result in growth inhibition due to 

DNA damage in repair-deficient strains of Bacillus 

subtilis (Kanematsu et al., 1980), an S-phase block 

(determined by flow cytometric analysis) was induced 

in cycling Chinese hamster ovary cells incubated with 

5/zg/mL nickel oxide (Costa et al., 1982). No 

increase in gene mutations was detected at the 

ouabain resistance locus in C3H/10T1/2 mouse 

embryo cells (Miura et al., 1989) or at the HPRT 

locus in hamster V79 cells after exposure to nickel 

oxide (Kargacin et al., 1993). However, positive 

effects were reported in mutation assays using a 

different site, the gpt gene, in V79 cells as the target 

for nickel oxide activity (Kargacin et al., 1993). No 

induction of chromosomal aberrations was detected in 

human fibroblast or leukocyte cultures exposed to 

nickel oxide for 24, 48, or 72 hours (Paton and 

Allison, 1972); however, the experimental protocol 

used in this test was designed for water-soluble 

compounds and may not have been suitable for 

testing insoluble nickel oxide. Data from human 

epidemiology studies indicate that exposure to nickel 

oxide-containing fumes or smelter dusts may induce 

chromosomal aberrations (Waksvik et al., 1984) and 

DNA-crosslinks (Costa et al., 1993) in peripheral 

blood lymphocytes of workers, but the evidence is 

weak. The link between nickel oxide and these 

genetic endpoints is confounded because smelter dusts 

and welding fumes contain other nickel compounds as 

well as other metals such as chromium and 

magnesium. Also, the genetic effects noted were not 

correlated with nickel concentrations in urine or 

blood, whereas increased DNA-crosslink frequencies 

noted after exposure to chromium-containing fumes, 

for example, were correlated with urine 

concentrations of the metal (Poppet al., 1992). 

Nickel sulfate hexahydrate did not induce gene 

mutations in Escherichia coli or Salmonella 

typhimurium (Arlauskas et al., 1985), and (in contrast to results reported for nickel oxide) no increases 

in gpt mutants were observed in hamster V79 cells 

treated with nickel sulfate hexahydrate (Christie, 

1989; Lee et al., 1993). However, nickel sulfate 

hexahydrate did induce mutations in L5178Y mouse 

lymphoma TK ÷/- cells treated with 500 to 

1,000/~g/mL in the absence of $9 metabolic activation enzymes (McGregor et al., 1988). In addition, 

nickel sulfate hexahydrate, administered by injection 

at doses of 200, 300, and 400 ppm, induced sexlinked recessive lethal mutations in germ cells of 

male Drosophila (Rodriguez-Arnaiz and Ramos, 

1986). The pre- and post-meiotic cell stages were 

affected; the broods obtained from sperm cells 

undergoing meiosis at the time of treatment showed 

no evidence of increased lethal mutations. In another 

test for germ cell effects in male Drosophila, the test 

for sex chromosome loss, only the highest dose of 

nickel sulfate hexahydrate (400 ppm) resulted in the 

production of XO males (Rodriguez-Arnaiz and 

Ramos, 1986). Induction of sister chromatid 

exchanges and chromosomal aberrations was 

observed in hamster cells (Larramendy et al., 1981; 

Ohno et al., 1982), as well as human peripheral 

lymphocytes (Larramendy et al., 1981) treated with 

nickel sulfate hexahydrate in vitro. However, no 

induction of DNA single strand breaks was detected 

in human xeroderma pigmentosum fibroblasts treated 

with 250/zg/mL nickel sulfate hexahydrate (Fornace, 

1982). In vivo, no induction of chromosomal aberrations was observed in rat bone marrow or spermatogonial cells after injection of nickel sulfate hexahydrate at doses that provided 3 or 6 mg nickel/kg 

body weight. Also, no change in the mitotic index of 

bone marrow cells was noted in treated animals 

(Mathur et al., 1978). 
34 Nickel Oxide, NTP TR 451 

As with the two nickel compounds discussed above, 

there are limited published mutagenicity data for the 

third nickel compound in the present studies, nickel 

subsulfide. However, results of in vitro tests performed with this insoluble nickel compound were 

mainly positive. In the Salmonella lyphimurium gene 

mutation assay, crystalline nickel subsulfide gave 

equivocal results in one study that used a preincubation protocol (Zeiger et al., 1992) and negative 

results in a standard plate incolrporation assay 

(Arrouijal et al., 1990). It induced lethal mutations 

in Paramecium tetraurelia, without $9 (SmithSonneborn et al., 1986) and unscheduled DNA 

repair in cultured Syrian hamster embryo cells 

(Robison et al., 1983). Treatment of cultured 

Chinese hamster ovary cells for 24 hours with 

10/zg/mL nickel subsulfide resulted in an increase in 

the number of DNA strand breaks detected by 

alkaline sucrose gradient techniques (Robison et al., 

1982). Nickel subsulfide, in the absence of $9, was 

a weak inducer of hypoxanthine phosphoribosyl 

transferase mutations in cultured Chinese hamster 

ovary cells (Rossetto et al., 1994) and sister chromatid exchanges in cultured human lymphocytes 

(Saxholm et al., 1981). Nickel subsulfide induced 

significant dose-related increases in chromosomal 

aberrations (Arrouijal et al., 1990) and micronuclei 

(Arrouijal etal., 1992) in human lymphocytes 

in vitro. One reported in vivo test with nickel 

subsulfide, a measure of DNA synthesis inhibition in 

rats administered 10/xg/rat (6 mg/100 g body weight) 

by intrarenal injection, was negative (Hui and 

Sunderman, 1980). A second in vivo study, a mouse 

bone marrow micronucleus test, reportedly produced 

positive results (Arrouijal et al., 1990). This second 

study, however, employed only a single dose 

(250 mg/kg nickel subsulfide administered by 

intraperitoneal injection), and no confirmatory study 

was conducted. 

STUDY RATIONALE 

The National Cancer Institute nominated nickel 

compounds for study because there was little information on the toxic and carcinogenic properties of 

specific nickel compounds after inhalation exposure. 

Nickel oxide and nickel sulfate hcxahydratc wcrc 

selected as compounds that are commonly found in 

the workplace in the United Statcs. Nickel subsulfidc 

was selected for study based on a previous study in 

which lung tumors wcrc observed in rats (Ottolcnghi 

et al., 1975). The NTP toxicity and carcinogcnicity 

studies of nickel oxide, nickel subsulfidc (NTP, 

1996a), and nickcl sulfate hcxahydratc (NTP, 1996b) 

wcrc performed to provide comparativc toxicology 

and carcinogcnicity information on these nickel 

compounds. The results of the nickel oxide studies 

arc prcscntcd in this Technical Report. 
Introduction 35 

NiaS2 

(2) 

Cytoplasm 

Ni +2 

(3) 

'~Ni+2 

Ni*2 

oxygen 

radicals 

DNA .. ~ -,,, 

Ni *2 Ni*3 

Protein DNA 

~I Ni(5121~~ 

damaged 

DNA 

Nucleus 

| 

J' 

X 

t~ 

# 

Ni *2 ~ Ni ÷2- P (1)~ 

NiCI 2 

FIGURE 1 

Possible Mechanisms of Nickel-Induced Genotoxicity 

1. Soluble nickel compounds such as nickel chloride diffuse into the cell; Ni +2 ions are rapidly bound to cytoplasmic proteins (P) (Lee et al., 1993). 2. Insoluble nickel compounds such as nickel subsulfide are phagocytized into ~he cell and move toward the nucleus (Costa et al., 1982). 3. Lysosomal breakdown of insoluble nickel compounds releases large quantities of Ni +2 ions which concentrate adjacent to 

the nuclear membrane (Costa and Heck, 1983). 4. Oxidative damage is induced in DNA by nickel ions bound to nuclear proteins 

(Ni +~ ~ Ni+3), releasing active oxygen species (Tkeshelashvili et al., 1993; Sugiyama, 1994). 5. DNA-protein crosslinks are produced by 

Ni ÷~ ions binding to heterochromatin (Lee et al., 1982; Patiemo and Costa, 1985; Sen and Costa, 1986a). 6. Binding of nickel ions to the 

heterochromatic regions of the long arm of the X chromosome, which may contain a senescence gene and a rumor suppressor gene, can 

cause deletion of all or part of this region, leading to an immortalization of the cell and clonal expansion (Conway and Costa, 1989; Klein et al., 1991). 
36 Nickel Oxide, NTP TR 451 
37 

MATERIALS AND METHODS 

PROCUREMENT AND 

CHARACTERIZATION 

OF NICKEL OXIDE 

Nickel oxide, which was manufactured by the Societe 

Metallurgique le Nickel (Paris, France), was generously supplied by International Nickel Company, Ltd. 

(Toronto, Ontario) in one lot 0042983). Identity and 

purity analyses were conducted by the analytical 

chemistry laboratory, Midwest Research Institute 

(Kansas City, MO) (Appendix K). Reports on 

analyses performed in support of the nickel oxide 

studies are on file at the National Institute of 

Environmental Health Sciences (NIEHS). 

The chemical, an olive gray powder, was characterized as very pure high temperature (sintered) green 

nickel .oxide by elemental analysis, melting point, 

weight loss on drying, spark source mass spectrometry, and solubility. Elemental analysis for nickel 

was in agreement with the theoretical value for nickel 

oxide. The melting point was greater than 300 ° C. 

Weight loss on drying indicated less than 0.05% 

water. Spark source mass spectrometry indicated the 

major inorganic impurities were cobalt 

(approximately 2,200 ppm), iron (670 ppm), and 

sulfur (200 ppm). The sample was not soluble in hot 

mineral acids, which is expected for sintered nickel 

oxide. A sample of lot 1042983 was analyzed for 

nickel, cobalt, copper, iron, and sulfur; results 

indicated conformance with American Society of 

Testing and Materials specifications for Grade 75 

nickel oxide sinter (ASTM, 1974). The overall 

purity was determined to be greater than 99 %. 

No accelerated chemical stability studies were performed for nickel oxide based on literature information about the physical and chemical properties of the 

compound (Kirk-Othmer, 1978). The melting point 

and oxidation state indicate that nickel oxide should 

be thermally stable at temperatures up to 340°C 

(Larkins, 1967; Weast, 1976). The bulk chemical 

was stored in amber glass bottles at room temperature. 

Periodic monitoring of the bulk chemical was performed by Huffman Laboratorie~,-Inc., (Golden, CO) 

using elemental analysis for nickel and weight loss on 

drying prior to all studies, once during the 16-day 

and 13-week studies and every 3 to 5 months during 

the 2-year studies. No change in the purity of the 

bulk chemical was observed during the studies. 

AEROSOL GENERATION 

AND EXPOSURE SYSTEM 

Nickel oxide aerosol was generated from 4-inch 

(16-day and 13-week studies) or 2-inch (2-year 

studies) fluid bed generators (FBGs). A Kr-85 

discharger was placed in the generator to reduce the 

electrical charge on the aerosol. The nickel oxide 

aerosol was mixed v~;ith diluting air to achieve the 

desired concentrations and was delivered to the 

exposure chambers. The aerosol generation assembly 

was enclosed in a walk-in hood. Air was circulated 

through HEPA filters to remove suspended particles 

in the enclosure. The aerosol delivery system is 

shown in Figure K2. 

Stainless steel, multi-tiered, whole-body exposure 

chambers (H1000 and H2000, Hazleton Systems, 

Aberdeen, MD) were used to expose the rats and 

mice in these studies (Figure K3). The air flow rate 

was monitored with orifice meters. The air flow rate 

in the 16-day and 13-week studies corresponded to 

3.68 to 21.32 (rats) and 10.06 to 19.44 (mice) air 

changes per hour. In the 2-year studies, the air flow 

rate corresponded to 15 _+ 2 air changes per hour. 

To reduce the spatial variation of aerosol concentration and to increase the uniformity of mixing, the 

aerosol was diluted in a radial dilutor prior to introduction into the chamber, and a small boxer fan 

(Model WS 2107FL-1002, Newark Electronics, 

Chicago, IL) was placed below the aerosol entrance 

to further mix the aerosol as it entered the chamber. 
38 Nickel Oxide, NTP TR 451 

AEROSOL CONCENTRATION 

MONITORING 

In the 13-week and 2-year studies, the aerosol 

concentrations were determined gravimetrically from 

three 2-hour samples (3 L/min flow rate) from each 

exposure chamber during each 6-hour exposure day. 

The background concentrations of total suspended 

particles in the control chambers were monitored 

each exposure day of the 2-year studies by collecting 

one 6-hour filter sample. Daily mean exposure 

concentrations for the 13-week studies are presented 

in Figures K6 and KT. Weekly mean exposure 

concentrations for the 2-year studies are presented in 

Figures K8 and K9. Good control of aerosol concentration was maintained. A continuous aerosol 

monitor (Model RAM-S, GCA, Co., Bedford, MA) 

was used to monitor the stability of the aerosol 

concentrations and to determine the need to adjust the 

aerosol generation system during exposures. The 

RAM-S was used to monitor each chamber for at 

least 2 minutes at the beginning, middle, and end of 

each filter sampling period. 

CHAMBER ATMOSPHERE 

CHARACTERIZATION 

Aerosol size distribution was determined with a 

cascade impactor once during the 16-day and 

13-week studies and monthly during the 2-year 

studies for each exposure chamber. The particle size 

was similar for all exposure concentrations and mass 

median aerodynamic diameters ranged from 1.89 to 

3.29/~m with geometric standard deviations ranging 

from 1.83 to 2.04 (Tables K1 through K4). Prior to 

the start of the studies, the generated aerosol was 

sampled and compared to the bulk sample by atomic 

absorption and X-ray diffraction analyses. The 

nickel content was identical for both samples, and the 

diffraction patterns conformed to reference patterns. 

The data support the conclusion that the crystal 

structure was not changed during the generation 

process. Uniformity of aerosol concentration in the 

exposure chambers was measured prior to the start of 

the studies without animals in the chambers and with 

animals during the first week of exposure, and was 

checked quarterly during the 2-year studies. The 

spatial variations ranged from 0% to 8.45% for all 

chambers. The time for the aerosol concentration in 

the chambers to reach 90% of the target (T90), 

determined with a RAM-S, was 8 minutes during all 

studies. The daily exposure time was set at 6 hours 

plus Tg0. 

16-DAY STUDIES 

Male and female F344/N rats and B6C3F~ mice were 

obtained from the Frederick Cancer Research Facility 

(Frederick, MD). On receipt, the rats and mice were 

approximately 4 weeks old. Animals were quarantined for 19 or 20 days and were approximately 

7 weeks old on the first day of exposure. Prior to 

study start, five male and five female rats and mice 

were randomly selected for parasite evaluation, gross 

observation for evidence of disease, and serologic 

testing. 

Groups of five male and five female rats and mice 

were exposed to nickel oxide by inhalation at concentrations of 0, 1.2, 2.5, 5, 10, or 30 mg nickel 

oxide/m 3 (equivalent to 0, 0.9, 2.0, 3.9, 7.9, or 

23.6 mg nickel/m3). The animals were exposed for 

6 hours plus Tg0 (8 minutes) per day, 5 days per 

week for 16 days. Feed was available ad libitum, 

except during exposure periods, and water was 

available ad libitum. Rats and mice were housed 

individually. Clinical findings were recorded initially 

and on day 5 for rats and mice. The animals were 

weighed initially, on day 4 or 5, and at the end of the 

studies. Details of the study design and animal 

maintenance are summarized in Table 4. 

In addition, a tissue burden study was performed on 

five male and five female rats exposed to 0, 1.2, 5, 

or 10 mg nickel oxide/m 3 and five male and five 

female mice exposed to 0, 1.2, 2.5, or 5 mg nickel 

oxide/m 3. The extent of distribution of inhaled nickel 

was determined in the right kidney and lung of rats 

and in the lung of mice (Table 4). Rats and mice 

were anesthetized with halothane and killed by 

cardiac puncture the morning following the last 

exposure. Tissue samples were digested with a 

mixture of nitric and hydrochloric acids and hydrogen peroxide and heated in a microwave oven. The 

digestates were diluted with deionized water 

(Millipore Co., Bedford, MA), and the nickel content 

was determined using electrothermal atomic absorption spectroscopy. Limits of detection and quantitation of the analytical method were calculated on a 

cumulative basis for each set of samples analyzed 
Materials and Methods 39 

according to a formula given by Keith et al. (1983). 

The results of tissue burden studies in the lung and 

kidney of rats and lung of mice are presented in 

Appendixes H and I. 

A necropsy was performed on all animals. The 

brain, heart, right kidney, liver, lung, right testis, 

and thymus of animals surviving until the end of the 

study were weighed. Tissues for microscopic examination were fixed and preserved in 10% neutral 

, 

buffered formalin, processed, trimmed, embedded in 

paraffin, sectioned to a thickness of 5 ~m, and 

stained with hematoxylin and eosin. A complete 

histopathologic examination was performed on all 0 

and 30 mg/m ~ rats and mice and on selected organs 

from rats and mice in all other exposure groups. 

Table 4 lists the tissues and organs that were examined. 

13-WEEK STUDIES 

These studies wcrc conducted to evaluate the cumulative toxic effects of repeated inhalation exposure to 

nickel oxide and to determine the appropriate exposure concentrations to be used in the 2-year 

studies. 

Male and female F344/N rats and B6C3F1 mice were 

obtained from Simonsen Laboratories (Gilroy, CA). 

Upon receipt, the rats and mice were approximately 

4 weeks old. Animals were quarantined for 19 or 

20 days and were approximately 7 weeks old on the 

first day of exposure. Prior to study start, five male 

and five female rats and mice were randomly selected 

for parasite evaluation, gross observation for evidence of disease, and serologic testing. At the end of 

the studies, serologic analyses were performed on 

groups of five male and five female control animals 

using the protocols of the NTP Sentinel Animal 

Program (Appendix M). 

Groups of 10 male and 10 female rats and mice were 

exposed to nickel oxide by inhalation at concentrations of 0, 0.6, 1.2, 2.5, 5, or 10 mg nickel oxide/m 3 

(equivalent to 0, 0.4, 0.9, 2.0, 3.9, or 7.9 mg 

nickel/m3). The animals were exposed for 6 hours 

plus Tgo (8 minutes) per day, 5 days per week for 

13 weeks (excluding one holiday). Feed was available ad libitum, except during exposure periods and 

water was available ad libitum. Rats and mice were 

housed individually. Clinical findings were recorded 

prior to the start of the study and then weekly for 

rats and mice. The animals were weighed initially, 

weekly thereafter, and at the end of the studies. 

Details of the study design and animal maintenance 

are summarized in Table 4. 

Tissue burden studies were performed to quantitate 

the extent of distribution of inhaled nickel in 18 male 

and 18 female rats and in six male and six female 

mice exposed to 0, 0.6, 2.5, or 10 mg/m 3. The 

lungs of six male and six female rats in each group 

after 4, 9, and 13 weeks and of all mice after 

13 weeks were analyzed using the same methods 

described for the 16-day studies (Table 4). Results 

of tissue burden studies in the lung of male rats and 

male mice are given in Appendixes H and I. 

At the end of the 13-week studies, samples were 

collected from core study rats and mice exposed to 0, 

2.5, 5, or 10 mg/m 3 for sperm morphology and 

vaginal cytology evaluations. The parameters evaluated are listed in Table 4. Methods used were those 

described in the NTP General Statement of Work 

(April, 1987). For 7 consecutive days prior to the 

end of the studies, the vaginal vaults of the females 

were moistened with saline, if necessary, and aspirated samples of vaginal fluid and cells were transferred to slides, air dried, fixed, and stained. Relative numbers of leukocytes, nucleated epithelial ceils, 

and large squamous epithelial cells were determined 

to ascertain estrous cycle stage (i.e., estrus, metestrus, diestrus, or proestrus). Male rats and mice 

were evaluated for sperm morphology, count, and 

motility. The right testis and epididymis were 

isolated and weighed. The tail of the epididymis 

(cauda epididymis) was removed from the epididymal 

body (corpus epididymis) and weighed. Test yolk 

(rats) or modified Tyrode's buffer (mice) was applied 

to slides and a small incision was made at the distal 

border of the cauda epididymis. The sperm effluxing 

from the incision were dispersed in the buffer on the 

slides, and the numbers of motile and nonmotile 

spermatozoa were counted by two observers in five 

fields per slide. Following completion of sperm 

motility estimates, the cauda epididymis was placed 

in buffered saline solution and finely minced; the 

tissue was incubated in the saline solution and heat 

fixed at 65 ° C. Sperm density was then determined 

microscopically using a hemocytometer. To quantify 
40 Nickel Oxide, NTP TR 451 

spermatogenesis, testicular spermatid head count was 

determined in the left testis by remoTing the tunica 

albuginea and homogenizing the testis in phosphatebuffered saline containing 10% dimethyl sulfoxide. 

Results of reproductive tissue evaluations and estrous 

cycle characterization are given in Appendix J. 

At the end of 13 weeks, hematology studies were 

performed on all surviving rats and mice. The 

animals were anesthetized with halothane and blood 

was collected by cardiac puncture and placed in tubes 

containing heparin as the anticoagulant. Hematology 

determinations were performed on a Coulter Electronics model S-550 hematology analyzer (Coulter 

Electronics, Hialeah, FL). Leukocyte differential 

and nucleated erythrocyte counts were determined by 

light microscopic examination of blood films stained 

with Wright-Giemsa. Reticulocyte counts were 

determined by light microscopy, using smears stained 

with new methylene blue. The hematology parameters measured are listed in Table 4. 

A necropsy was performed on all animals. The 

brain, heart, right kidney, liver, lung, right testis, 

and thymus of animals surviving until the end of the 

study were weighed. Tissues for microscopic examination were fixed and preserved in 10% neutral 

buffered formalin, processed, trimmed, embedded in 

paraffin, sectioned to a thickness of 5 to 6 ~m, and 

stained with hematoxylin and eosin. A complete 

histopathologic examination was performed on all 0 

and 10 mg/m 3 rats and mice, and on selected organs 

from rats and mice in the other exposure groups. 

Table 4 lists the tissues and organs that were examined. 

2-YEAR STUDIES 

Study Design 

Groups of 65 male and 65 female rats were exposed 

to nickel oxide by inhalation at concentrations of 0, 

0.62, 1.25, or 2.5 mg nickel oxide/m 3 (equivalent to 

0, 0.5, 1.0, or 2.0 mg nickel/m 3) and groups of as 

many as 79 male and 76 female mice were exposed 

to nickel oxide by inhalation at concentrations of 0, 

1.25, 2.5, or 5 mg nickel oxide/m 3 (equivalent to 0, 

1.0, 2.0, or 3.9 mg nickel/m 3) for 6 hours plus T90 

(8 minutes) per day, 5 days per week for 104 weeks, 

excluding holidays. After 7 months of exposure, as 

many as seven male and seven female rats and five 

male and five female mice from each exposure group 

were evaluated for histopathology and tissue burden. 

After 15 months of exposure, five male and five 

female rats and mice were evaluated for hematology 

parameters, histopathology, and tissue burden. 

Source and Specification of Animals 

Male and female F344/N rats were obtained from 

Taconic Farms (Germantown, NY) and male and 

female B6C3F~ mice were obtained from Simonsen 

Laboratories (Gilroy, CA) for use in the 2-year 

studies. Upon receipt the animals were 4 weeks old. 

Animals were quarantined for 11 days before the 

beginning of the studies and were approximately 6 

weeks old on the first day of exposure. Prior to 

study start, five male and five female rats and mice 

were randomly selected for parasite evaluation and 

gross observation for evidence of disease. The health 

of the animals was monitored during the studies 

according to the protocols of the NTP Sentinel 

Animal Program (Appendix M). 

Animal Maintenance 

Rats and mice were housed individually. Feed was 

available ad libitum, except during exposure periods, 

and water was available ad libitum. Cages and racks 

were rotated weekly. Further details of animal 

maintenance are given in Table 4. Information on 

feed composition and contaminants is provided in 

Appendix L. 

Clinical Examinations and Pathology 

The animals were observed twice daily for signs of 

toxicity, mortality, or moribundity. Clinical findings 

and body weights were recorded initially, weekly for 

the first 13 weeks, monthly thereafter, and at the end 

of the studies. 

At 15 months, rats and mice were anesthetized with 

carbon dioxide and blood was drawn from the 

retroorbital sinus and placed in tubes containing 

potassium EDTA as the anticoagulant. The hematology parameters measured are listed in Table 4. 

Lung samples for determination of tissue burden were 

collected from rats exposed to 0, 0.62, 1.25, or 

2.5 mg/m 3 and from mice exposed to 0, 1.25, 2.5, or 

5 mg/m 3 after 7 and 15 months and were analyzed 

using the same methods used in the 16-day studies. 
Materials and Methods 41 

The results of the tissue burden studies are found in 

Appendixes H and I. 

A complete necropsy and microscopic examination 

were performed on all rats and mice. The brain, 

right kidney, liver, lung, spleen, and thymus of all 

animals at both interim evaluations and all animals 

surviving until the end of the studies were weighed as 

were the right testes from males at the 7-month 

interim evaluation. At necropsy, all organs and 

tissues were examined for grossly visible lesions, and 

all major tissues were fixed and preserved in 10% 

neutral buffered formalin, processed, trimmed, 

embedded in paraffin, sectioned to a thickness of 5 to 

6 /zm, and stained with hematoxylin and eosin for 

microscopic examination. For all paired organs (i.e., 

kidney, ovary, adrenal gland), samples from each 

organ are examined. Tissues examined microscopically are listed in Table 4. 

Microscopic evaluations were completed by the study 

laboratory pathologist, and the pathology data were 

entered into the Toxicology Data Management 

System. The microscopic slides, paraffin blocks, and 

residual wet tissues were sent to the NTP Archives 

for inventory, slide/block match, and wet tissue 

audit..The slides, individual animal data records, 

and pathology tables were evaluated by an independent quality assessment laboratory. The individual 

animal records and tables were compared for 

accuracy, the slide and tissue counts were verified, 

and the histotechnique was evaluated. For the 2-year 

studies, a quality assessment pathologist reviewed the 

lung, bronchial and mediastinal lymph nodes, and 

adrenal gland medulla in rats and the lung, nose, and 

bronchial lymph nodes in mice for all neoplastic and 

nonneoplastic lesions. All diagnosed neoplasms from 

all organs in rats and mice, with the exception of 

interstitial cell adenomas of the testis in rats, were 

also reviewed. 

The quality assessment report and slides were submitted to the NTP Pathology Working Group (PWG) 

chair, who reviewed the selected tissues and any 

other tissues for which a disagreement in diagnosis 

between the laboratory and quality assessment pathologists existed. Representative histopathology slides 

containing examples of lesions related to chemical 

administration, examples of disagreements in 

diagnoses between the laboratory and qualitty assessment pathologist, or lesions of general interest were 

presented by the chair to the PWG for review. The 

PWG consisted of the quality assessment pathologist 

and other pathologists experienced in rodent toxicologic pathology. This group examined the tissues 

without any knowledge of dose groups. When the 

PWG consensus differed from the opinion of the 

laboratory pathologist, the diagnosis was changed. 

Thus, the final diagnoses represent a consensus of 

contractor pathologists and the PWG. Details of 

these review procedures have been described, in part, 

by Maronpot and Boorman (7982) and Boorman 

et al. (1985). For subsequent analyses of the pathology data, the diagnosed lesions for each tissue type 

were evaluated separately or combined according to 

the guidelines of McConnell et al. (1986). 

STATISTICAL METHODS 

Survival Analyses 

The probability of survival was estimated by the 

product-limit procedure of Kaplan and Meier (1958) 

and is presented in the form of graphs. Animals 

found dead of other than natural causes or missexed 

were censored from the survival analyses; animals 

dying from natural, causes were not censored. 

Statistical analyses for possible dose-related effects 

on survival used Cox's (1972) method for testing two 

groups for equality and Tarone's (1975) life table test 

to identify dose-related trends. All reported P values 

for the survival analyses are two sided. 

Calculation of Incidence 

The incidences of neoplasms or nonneoplastic lesions 

as presented in Tables A1, A5, B1, B5, C1, C5, D1, 

and D5 are given as the number of animals bearing 

such lesions at a specific anatomic site and the 

number of animals with that site examined microscopically. For calculation of statistical significance, 

the incidences of most neoplasms (Tables A3, B3, 

C3, and D3) and all nonneoplastic lesions are given 

• as the numbers of animals affected at each site 

examined microscopically. However, when macroscopic examination was required to detect neoplasms 

in certain tissues (e.g., skin, intestine, harderian 

gland, and mammary gland) before microscopic 

evaluation, or when neoplasms had multiple potential 

sites of occurrence (e.g., leukemia or lymphoma), the 

denominators consist of the number of animals on 

which a necropsy was performed. Tables A3, B3, 
42 Nickel Oxide, NTP TR 451 

C3, and D3 also give the survival-adjusted neoplasm 

rate for each group and each site-specific neoplasm, 

i.e., the Kaplan-Meier estimate of the neoplasm 

incidence that would have been observed at the end 

of the study in the absence of mortality from all other 

competing risks (Kaplan and Meier, 1958). 

Analysis of Neoplasm Incidences 

The majority of neoplasms in these studies were 

considered to be incidental to the cause of death or 

not rapidly lethal. Thus, the primary statistical 

method used was logistic regression analysis, which 

assumed that the diagnosed neoplasms were discovered as the result of death from an unrelated 

cause and thus did not affect the risk of death. In 

this approach, neoplasm prevalence was modeled as 

a logistic function of chemical exposure and time. 

Both linear and quadratic terms in time were incorporated initially, and the quadratic term was eliminated if the fit of the model was not significantly 

enhanced. The neoplasm incidences of exposed and 

control groups were .compared on the basis of the 

likelihood score test for the regression coefficient of 

dose. This method of adjusting for intercurrent 

mortality is the prevalence analysis of Dinse and 

Lagakos (1983), further described and illustrated by 

Dinse and Haseman (1986). When neoplasms are 

incidental, this comparison of the time-specific 

neoplasm prevalences also provides a comparison of 

the time-specific neoplasm incidences (McKnight and 

Crowley, 1984). 

In addition to logistic regression, other methods of 

statistical analysis were used, and the results of these 

tests are summarized in the appendixes. These 

methods include the life table test (Cox, 1972; 

Tarone, 1975), appropriate for rapidly lethal neoplasms, and the Fisher exact test and the CochranArmitage trend test (Armitage, 1971; Gart et al., 

1979), procedures based on the overall proportion of 

neoplasm-bearing animals. 

Tests of significance included pairwise comparisons 

of each exposed group with controls and a test for an 

overall dose-related trend. Continuity-corrected tests 

were used in the analysis of neoplasm incidence, and 

reported P values are one sided. The procedures 

described in the preceding paragraphs were also used 

to evaluate selected nonneoplastic lesions. For 

further discussion of these statistical methods, refer 

to Haseman (1984). 

Analysis of Nonneoplastic Lesion Incidences 

Because all nonneoplastic lesions in this study were 

considered to be incidental to the cause of death or 

not rapidly lethal, the primary statistical analysis used 

was a logistic regression analysis in which nonneoplastic lesion prevalence was modeled as a logistic 

function of chemical exposure and time. For lesions 

detected at the interim evaluations, the Fisher exact 

test, a procedure based on the overall proportion of 

affected animals, was used. 

Analysis of Continuous Variables 

Two approaches were employed to assess the significance of pairwise comparisons between exposed and 

control groups in the analysis of continuous 

variables. Organ and body weight data, which have 

approximately normal distributions, were analyzed 

using the parametric multiple comparison procedures 

of Dunnett (1955) and Williams (1971, 1972). 

Hematology, spermatid, epididymal spermatozoa, and 

tissue burden data, which have typically skewed 

distributions, were analyzed using the nonparametric 

multiple comparison methods of Shirley (1977)and 

Dunn (1964). Jonckheere's test (1954) was used to 

assess the significance of the dose-related trends and 

to determine whether a trend-sensitive test (Williams' 

or Shirley's test) was more appropriate for pairwise 

comparisons than a test that does not assume a 

monotonic dose-related trend (Dunnett's or Dunn's 

test). Average severity values were analyzed for 

significance using the Mann-Whitney U test 

(Hollander and Wolfe, 1973). Because the vaginal 

cytology data are proportions (the proportion of the 

observation period that an animal was in a given 

estrous stage), an arcsine transformation was used to 

bring the data into closer conformance with normality 

assumption. Treatment effects were investigated by 

applying a multivariate analysis of variance 

(Morrison, 1976) to the transformed data to test for 

simultaneous equality of measurements across exposure levels. 
Materials and Methods 43 

Historical Control Data 

Although the concurrent control group is always the 

first and most appropriate control group used for 

evaluation, historical control data can be helpful in 

the overall assessment of neoplasm incidence in 

certain instances. Consequently, neoplasm incidences 

from the NTP historical control database (Haseman 

et al., 1984, 1985) are included in the NTP reports 

for neoplasms appearing to show compound-related 

effects. 

QUALITY ASSURANCE METHODS 

The 13-week and 2-year studies were conducted in 

coml~liance with Food and Drug Administration Good 

Laboratory Practice Regulations (21 CFR, Part 58). 

In addition, as records from the 2-year studies were 

submitted to the NTP Archives, these studies were 

audited retrospectively by an independent quality 

assurance contractor. Separate audits covering 

completeness and accuracy of the pathology data, 

pathology specimens, final pathology tables, and a 

draft of this NTP Technical Report were conducted. 

Audit procedures and findings are presented in the 

reports and are on file at NIEHS. The audit findings 

were reviewed and assessed by NTP staff, so all 

comments had been resolved or were otherwise 

addressed during the preparation of this Technical 

Report. 

GENETIC TOXICOLOGY 

The genetic toxicity of nickel oxide was assessed by 

testing the ability of the chemical to increase the 

frequency of micronucleated erythrocytes in peripheral blood. The protocol for these studies and the 

results are given in Appendix E. 

The genetic toxicity studies of nickel oxide are part 

of a larger effort by the NTP to develop a database 

that would permit the evaluation of carcinogenicity in 

experimental animals from the structure and responses of the chemical in short-term in vitro and in vivo 

genetic toxicity tests. These genetic toxicity tests 

were originally developed to study mechanisms of 

chemically induced DNA damage and to predict 

carcinogenicity in animals, based on the electrophilic 

theory of chemical carcinogenesis and the somatic 

mutation theory (Miller and Miller, 1977; Straus, 

1981; Crawford, 1985). 

There is a strong correlation between a chemical's 

potential electrophilicity (structural alert to DNA 

reactivity), mutagenicity in Salmonella, and carcinogenicity in rodents. The combination of electrophilicity, and Salmonella mutagenicity is highly 

correlated with the induction of carcinogenicity in 

rats and mice and/or at multiple tissue sites (Ashby 

and Tennant, 1991). Other in vitro genetic toxicity 

tests do not correlate well with rodent carcinogenicity 

(Tennant et al., 1987; Zeiger et al., 1990), although 

these other tests can provide information on the types 

of DNA and chromosome effects that can be induced 

by the chemical being investigated. Data from NTP 

studies show that a positive response in Salmonella is 

currently the most predictive in vitro test for rodent 

carcinogenicity (89% of the Salmonella mutagens 

were rodent carcinogens), and that there is no complementarity among the in vitro genetic toxicity tests. 

That is, no battery of tests that included the 

Salmonella test improved the predictivity of the 

Salmonella test alone. The predictivity for carcinogenicity of a positive response in bone marrow 

chromosome aberration or micronucleus tests is not 

yet defined. 
44 Nickel Oxide, NTP TR 451 

TABLE 4 

Experimental Design and Materials and Methods in the Inhalation Studies of Nickel Oxide 

16-Day Studies 13-Week Studies 2-Year Studies 

Study Laboratory 

Lovelace Inhalation Toxicology 

Research Institute 

(Albuquerque, NM) 

Strain and Species 

Rats: F344/N 

Mice: B6C3F1 

Animal Source 

Frederick Cancer Research Facility 

(Frederick, MD) 

Time Held Before Studies 

19 days (males) or 20 days (females) 

Average AgeWhen Studies Began 

7 weeks 

Date of FirstDose 

Rats: 27 (males) or 28 (females) 

January 1986 

Mice: 3 (males) or 4 (females) 

February 1986 

Duration of Dosing 

6 hours/day, 5 days/week for 16 days 

Date of Last Dose 

Rats: 11 (males) or 12 (females) 

Febmary 1986 

Mice: 18 (males) or 19 (females) 

Febmary 1986 

Lovelace Inhalation Toxicology 

Research Institute 

(Albuquerque, NM) 

Rats: F344/N 

Mice: B6C3F 1 

Simonsen Laboratories 

(Gilroy, CA) 

19 days (males) or 20 days (females) 

7 weeks 

Rats: 14 (males) or 15 (females) 

July 1986 

Mice: 21 (males) or 22 (females) 

July 1986 

6 hours/day, 5 days/week for 

13 weeks (excluding one holiday) 

Rats: 15 (males) or 17 (females) 

October 1986 

Mice: 21-22 (males) or 23-24 

(females) October 1986 

Lovelace Inhalation Toxicology 

Research Institute 

(Albuquerque, NM) 

Rats: F344/N 

Mice: B6C3F1 

Rats: Taeonic Farms 

(Germantown, NY) 

Mice: Simonsen Laboratories 

(Gilroy, CA) 

11 days 

6 weeks 

Rats: 4 April 1988 

Mice: 25 April 1988 

6 hours/day, 5 days/week for 

104 weeks (excluding holidays) 

Rats 

7-Month interim evaluation: 

18-19 October 1988 

15-Month interim evaluation: 

5-6 July 1989 

Terminal sacrifice: 30 March 1990 

Mice 

7-Month interim evaluation: 

8-9 November 1988 

15-Month interim evaluation: 

25-26 July 1989 

Terminal sacrifice: 20 April 1990 
Materials and Methods 45 

TABLE 4 

Experimental Design and Materials and Methods in the Inhalation Studies of Nickel Oxide (continued) 

16-Day Studies 13-Week Studies 2-Year Studies 

Necropsy Dates 

Rats: 12 (males) or 13 (females) 

February 1986 

Mice: 19 (males) or 20 (females) 

February 1986 

Average Age at Necropsy 

9 weeks 

Size of Study Groups 

Core study: 5 males and 5 females 

Tissue burden study: 5 males and 

5 females 

Method of Distribution 

Animals were distributed randomly into 

groups of approximately equal initial 

mean body weights. 

Rats: 15-16 (males) or 17-18 (females) 

October 1986 

Mice: 22-23 (males) or 24-25 

(females) October 1986 

20 weeks 

Core study: 10 males and 10 females 

Tissue burden study: 18 male and 

18 female rats; 6 male and 

6 female mice 

Same as 16-day studies 

Rats 

7-Month interim evaluation: 

19-20 October 1988 

15-Month interim evaluation: 

6-7 July 1989 

Terminal sa~r.ifice: 6-10 (males) or 

2-5 (females) April 1990 

Mice 

7-Month interim evaluation: 

9-10 November 1988 

15-Month interim evaluation: 

26-27 July 1989 

Terminal sacrifice: 1-3 May (males) 

or 23-30 April (females) 1990 

7-Month interim evaluation: 34 weeks 

15-Month interim evaluation: 

71 weeks 

Terminal sacrifice: 111 weeks 

Core study: 

7-Month interim evaluation: as many 

as 7 male and 7 female rats; 

5 male and 5 female mice 

15-Month interim evaluation: 5 male 

and 5 female rats and mice 

2-Year study: 53 or 54 male and 

female rats; 67 (0 mg/m3), 

67 (1.25 mg/m3), 66 (2.5 mg/m3), 

and 69 (5 mg/m 3) male and 64, 

66, 63, and 64 female mice 

Tissue burden study: 

7-Month interim evaluation: 7 male 

and 7 female rats; 5 male and 

5 female mice 

15-Month interim evaluation: 5 male 

and 5 female rats and mice 

Same as 16-day studies 
46 Nickel Oxide, NTP TR 451 

TABLE 4 

Experimental Design and Materials and Methods in the Inhalation Studies of Nickel Oxide (continued) 

16-Day Studies 13-Week Studies 2-Year Studies 

Animals per Cage 

1 1 

Method of Animal Identification 

Toe clip, ear tag, and location within 

chamber unit 

Diet 

Zeigler NIH-07 open formula meal diet 

(Zeigler Brothers, Inc., Gardners, PA), 

available ad libitum, except during 

exposure periods, changed at least once 

weekly 

Water Distribution 

Tap water (Albuquerque.~nunicipal 

supply) via automatic watering system 

(Edstrom Industries, Waterford, WI), 

available ad libitum; checked twice 

daily 

Cages 

Stainless steel (Hazleton Systems, Inc., 

Aberdeen, MD), rotated every 

4 exposure days and changed weekly 

Bedding/Cageboard 

Techboard untreated paper (Shepherd 

Specialties Paper, Inc., Kalamazoo, 

MI), changed twice daily 

Room/Chamber Air Supply Filters 

High efficiency particulate air filter 

MIL Spec MIL-F-51068C (Flanders, 

Washington, DC); changed as required 

Chambers 

Stainless steel (Hazleton Systems, Inc., 

Aberdeen, MD), changed weekly 

Chamber Environment 

Temperature: 19.8 ° to 24.1 ° C 

Relative humidity: 13.3% to 96.0% 

Fluorescent light: 12 hours/day 

Chamber air: 12 5:2 changes/hour 

Tail tattoo, ear tag, and cage location 

Zeigler NIH-07 open formula diet 

(Zeigler Brothers, Inc., Gardners, PA), 

available ad libitum, except during 

exposure periods, changed weekly 

Same as 16-day studies 

Same as 16-day studies 

Same as 16-day studies 

Same as 16-day studies 

Sameas 16-day studies 

Temperature: 20.1 ~ to 27.2 ° C 

Relative humidity: 12.3% to 98.0% 

Fluorescent light: 12 hours/day 

Chamber air: 12 5:2 changes/hour 

Rats: Tail tattoo 

Mice: Tail tattoo and ear tag 

Same as 13-week studies 

Same as 16-day studies 

Same as 16-day studies 

Same as 16-day studies 

Same as 16-day studies 

Same as 16-day studies 

Temperature: 22.1 ° to 25.7 ° C 

Relative humidity: 31.8% to 69.1% 

Fluorescent light: 12 hours/day 

Chamber air: 3.68 to 21.32 (rats) and 

10.06 to 19.44 (mice) changes/hour 
Materials and Methods 47 

TABLE 4 

Experimental Design and Materials and Methods in the Inhalation Studies of Nickel Oxide (continued) 

16-Day Studies 13-Week Studies 2-Year Studies 

Doses 

Core study: 0, 1.2, 2.5, 5, 10, or 

30 mg nickel oxide/m 3 (0, 0.9, 

2.0, 3.9, 7.9, or 23.6 mg 

nickel/m 3) 

Tissue burden study in rats: 0, 1.2, 5, 

or 10 mg nickel oxide/m 3 (0, 0.9, 

3.9, or 7.9 mg nickel/m 3) 

Tissue burden study in mice: 0, 1.2, 

2.5, and 5 mg nickel oxide/m 3 (0, 

0.9, 2.0, or 3.9 mg nickel/m 3) 

Type and Frequency of Observation 

Observed twice daily; animals were 

weighed initially, after 4 or 5 days of 

exposure, and at the end of the studies. 

Clinical observations were recorded 

initially and after 5 days of exposure. 

Method of Sacrifice 

Exsanguination under halothane 

anesthesia 

Necropsy 

Necropsy performed on all animals. 

Organs weighed were brain, heart, 

right kidney, liver, lung, right testisl 

and thymus. 

Clinical Pathology 

None 

Core study: 0, 0.6, 1.2, 2.5, 5 or 

10 mg nickel oxide/m 3 (0, 0.4, 

0.9, 2.0, 3.9, or 7.9 mg nickel/m 3) 

Tissue burden study: 0, 0.6, 2.5, or 

10 mg nickel oxide/m 3 (0, 0.4, 

2.0, or 7.9 mg nickel/m 3) 

Observed twice daily; animals were 

weighed initially, weekly thereafter, 

and at the end of the studies. Cliiaical 

observations were recorded initially 

and weekly thereafter. 

Same as 16-day studies 

Necropsy performed on all animals. 

Organs weighed were brain, heart, 

right kidney, liver, lung, right testis 

and thymus. 

Blood was collected by cardiac 

puncture from all core study rats and 

mice surviving to study termination for 

hematology. 

Hematology: hematocrit, hemoglobin 

concentration, erythrocytes, mean cell 

volume, mean cell hemoglobin 

concentration, total leukocytes and 

differentials, reticulocytes, and 

nucleated erythrocytes. 

Rats: 0, 0.62, 1.25, or 2.5 mg nickel 

oxide/m 3 (0, 0.5, 1.0, or 2.0 mg 

nickel/m 3) 

Mice: 0, 1.25, 2.5, or 5 mg nickel 

oxide/m 3 (0, 1.0, 2.0, or 3.9 mg 

nickel/m 3) 

Observed twice daily; animals were 

weighed and clinical observations were 

recorded initially, weekly for 

13 weeks, monthly thereafter, and at 

the end of the studies. 

Exsanguination under carbon dioxide 

anesthesia 

Necropsy performed on all animals. 

Organs weighed at the 7- and 15-month 

interim evaluations were brain, right 

kidney, liver, lung, spleen, right testis 

(7-month interim evaluation only), and 

thymus. 

Blood was collected from five male and 

four to five female rats and mice at the 

15-month interim evaluation from the 

retroorbital sinus for hematology. 

Hematology: hematocrit, hemoglobin 

concentration, erythrocytes, mean cell 

volume, mean cell hemoglobin, mean 

cell hemoglobin concentration, total 

leukocytes and differentials, 

reticulocytes, and nucleated 

erythrocytes. 
48 Nickel Oxide, NTP TR 451 

TABLE 4 

Experimental Design and Materials and Methods in the Inhalation Studies of Nickel Oxide (continued) 

16-Day Studies 13-Week Studies 2-Year Studies 

Histopathology 

Complete histopathology was 

performed on all 0 and 30 mg/m 3 rats 

and mice. In addition to gross lesions 

and tissue masses with regional lymph 

nodes, tissues examined included: 

adrenal gland, bone and marrow, 

brain, clitoral gland (rats), epididymis, 

esophagus, gallbladder (mice), heart, 

kidney, large intestine (colon, cecum, 

and rectum) larynx, liver, lung, lymph 

nodes (bronchial, mandibular, 

mediastinal, and mesenteric), mammary 

gland, muscle, nose, ovary, pancreas, 

parathyroid gland, pituitary gland, 

preputial gland (rats), prostate, salivary 

gland, seminal vesicle, skin, small 

intestine (duodenum, jejunum, and 

ileum), spleen, stomach (forestomach 

and glandular), testis, thymus, thyroid 

gland, trachea, urinary bladder, and 

uterus. The lung of 1.2, 2.5, 5, and 

10 mg/m 3 animals; bronchial lymph 

nodes and thymus of 5 and 10 mg/m 3 

animals; and mediastinal lymph nodes 

and nasal turbinates of 10 mg/m 3 

animals were also examined. 

Complete histopathology was 

performed on all rats and 0 and 

10 mg/m 3 mice. In addition to gross 

lesions and tissue masses with regional 

lymph nodes, tissues examined 

included: adrenal gland, bone and 

marrow, brain, clitoral gland (rats), 

epididymis, esophagus, gallbladder 

(mice), heart, kidney, large intestine 

(colon, cecum, and rectum) larynx, 

liver, lung, lymph nodes (bronchial, 

mandibular, mediastinal, and 

mesenteric), mammary gland, muscle, 

nose, ovary, pancreas, parathyroid 

gland, pituitary gland, preputial gland 

(rats), prostate, salivary gland, seminal 

vesicle, skin, small intestine 

(duodenum, jejunum, and ileum), 

spleen, stomach (forestomach and 

glandular), testis, thymus, thyroid 

gland, trachea, urinary bladder, and 

uterus. The lung, bronchial lymph 

nodes, and nose were also examined in 

all other groups of mice. 

Tissue Burden Analyses 

Lung and/or kidney (see Appendixes H 

and I) 

Lung (see Appendixes H and I) 

Sperm Morphology and Vaginal Cytology Evaluations 

None At the end of the studies sperm 

samples were collected from all male 

animals in the 0, 2.5, 5, and 10 mg/m 3 

groups for sperm morphology 

evaluations. The parameters evaluated 

were: sperm density, morphology, and 

motility. The fight cauda, right 

epididymis, and right testis were 

weighed. Vaginal samples were 

collected for up to 7 consecutive days 

prior to the end of the studies from all 

female ani~mals in the 0, 2.5, 5, and 

10 mg/m 3 groups for vaginal cytology 

evaluations. The parameters evaluated 

were relative frequency of estrous 

stages and estrous cycle length. 

Complete histopathology was 

performed on all rats and mice, with 

the exception bf animals evaluated at 

7 months in which only kidney, lung, 

lymph nodes (bronchial and 

mediastinal), and nasal turbinates were 

examined. For all others, in addition 

to gross lesions and tissue masses with 

regional lymph nodes, tissues examined 

included: adrenal gland, bone and 

marrow, brain, clitoral gland, 

esophagus, gallbladder (mice), heart, 

kidney, large intestine (cecum, colon, 

rectum), larynx, liver, lung, lymph 

nodes (bronchial, mandibular, 

mediastinal, and mesenteric), mammary 

gland, muscle, nose (3 levels), ovary, 

pancreas, parathyroid gland, pituitary 

gland, preputial gland, prostate gland, 

salivary gland, seminal vesicle, skin, 

small intestine (duodenum, jejunum, 

ileum), spleen, stomach (forestomach 

and glandular) testis, thymus, thyroid 

gland, urinary bladder, and uterus. 

Lung (see Appendixes H and I) 

None 
49 

RESULTS 

RATS 

16-DAY STUDY 

All rats survived to the end of the study (Table 5). 

Final mean body weights and mean body weight 

gains of exposed male and female rats were similar 

to those of the controls, and no clinical findings in 

any group were related to nickel oxide exposure. 

TABLE 5 

Survival and Body Weights of Rats in the 16-Day Inhalation Study of Nickel Oxide 

Mean Body Weight b (g) Final Weight 

Dose Survival a Initial Final Change Relative to Controls 

(mg/m a) (%) 

Male 

0 5/5 143 5: 3 213 5:5 70 5:2 

1.2 5/5 144 5:3 211 5:4 67. 5:4 99 

2.5 5/5 142 5:5 214 5:6 72 5: 3 101 

5 5/5 144 5:2 210 5:4 66 5: 3 99 

10 5/5 142 5:4 210 5:4 69 5: 3 99 

30 5/5 139 5:5 204 5:5 65 ± 3 96 

Female 

0 5/5 121 5:2 150 5:2 28 5:1 

1.2 5/5 122 5:3 155 5:3 32 5:2 103 

2.5 5/5 123 5:3 154 5:4 31 5: 3 103 

5 5/5 124 5: I 156 5:2 32 5: 1 104 

10 5/5 124 5:2 150 5:2 26 5:4 101 

30 5/5 123 5:2 149 5:3 26 5:4 99 

a Number of animals surviving at 16 days/number initially in group 

b Weights and weight changes are given as mean 5: standard error. Differences from the control group were not significant by Dunnett's 

test. 
50 Nickel Oxide, NTP TR 451 

Absolute and relative lung weights, of I0 and 

30 mg/m 3 males and females were significantly 

greater than those of the controls (Table F1). At 

necropsy, chemical-related gross lesions were limited 

to a slight enlargement of the bronchial lymph nodes 

in two male and two female rats exposed to 

30 mg/m 3. The lymph node enlargement was attributed to lymphoid hyperplasia, which was evident by 

microscopic examination of the bronchial lymph 

nodes of most 30 mg/m 3 males and females. In 

addition to those in the lymph nodes, histopathologic 

changes were also present in the lungs and nose 

(Table 6). In most rats exposed to 10 or 30 mg/m 3, 

inflammatory cell infiltrates in the alveolar interstitium, foci of acute inflammation (neutrophilic 

infiltrates), and an increase in the number of alveolar 

macrophages in the lungs were observed. Pigment, 

consisting of densely stained black particles, was 

present in the cytoplasm of alveolar macrophages as 

well as extracellularly within the alveolar spaces. At 

the lower exposure concentrations, histopathologic 

changes were limited to accumulation of alveolar 

macrophages and the presence of black pigment 

particles in the lung. Minimal atrophy of the olfactory epithelium in the nose was also present in one 

male and one female exposed to 30 mg/m 3. 

TABLE 6 

Incidences of Selected Nonneoplastic Lesions in Rats in the 16-Day Inhalation Study of Nickel Oxide 

0 mg/m 3 1.2 mg/m 3 2.5 mg/m 3 5 mg/m 3 10 mg/m 3 30 mg/m 3 

Male 

Lung a 5 5 

Alveolar Macrophage Hyperplasia b 0 2 (1.0) c 

Inflammation 0 0 

Interstitial Infiltrate 0 0 

Pigment 0 5** (1.0) 

Lymph Node, Bronchial 4 

Hyperplasia 0 

Nose 5 

Atrophy, Olfactory Epithelium 0 

d 

5 5 5 5 

3 (1.0) 5** (1.0) 5** (1.6) 5** (3.0) 

0 0 2 (1.0) 5** (2.8) 

0 0 0 5** (2.8) 

5** (1.0) 5** (2.0) 5** (2.2) 5** (3.0) 

3 3 4 

0 1 (1.0) 4* (3.0) 

5 5 

0 ~ (~.0) 

Female 

Lung 5 5 

Alveolar Macrophage Hyperplasia 0 0 

Inflammation 0 0 

Interstitial Infiltrate 0 0 

Pigment 0 5** 

Lymph Node, Bronchial 4 

Hyperplasia 0 

Nose 5 

Atrophy, Olfactory Epithelium 0 

(1.o) 

5 5 5 5 

0 4* (1.0) 5** (2.0) 5** (3.0) 

0 0 5** (2.0) 5** (2.8) 

0 0 5** (2.0) 5** (3.0) 

5** (1.0) 5** (1.8) 5** (2.8) 5** (3.0) 

4 4 4 

0 1 (2.0) 3 (310) 

5 5 

0 1 (1.0) 

* Significantly different (P <_0.05) from the control group by the Fisher exact test 

** P<_0.01 

a Number of animals with organ examined microscopically 

b Number of animals with lesion 

c Average severity of lesions in affected animals: 1 = minimal; 2 = mild; 3 = moderate; 4 = marked 

d Tissue not examined at this exposure concentration 
Results 51 

Nickel concentrations in the lungs of 1.2, 5, and 

10 mg/m 3 males and females were greater than those 

in the controls and increased with exposure concentration, and the absolute lung weights of these 

10 mg/m 3 males and females were significantly 

greater than those of the controls (Tables 7 and HI). 

Nickel concentrations in the kidney of 10 mg/m 3 

male and female rats were below the limit of detection; however, the absolute kidney weight of these 

females was significantly greater than that of the 

controls (Table H2). 

Because of the severity of lung lesions in rats 

exposed to 30 mg/m 3, 10 mg/m 3 was selected as the 

highest exposure concentration for the 13-week 

study. 

TABLE 7 

Lung Weight and Lung Burden in Rats in the 16-Day Inhalation Study of Nickel Oxide a 

0 mg/m 3 1.2 mg/m 3 5 mg/m 3 10 mg/m 3 

n 5 5 5 5 

Male 

Absolute lung W t (g) 0.856 ± 0.047 0.870 ± 0.046 0.822 ± 0.041 1.068 ± 0.056* 

/~g Ni/lung _b 36 ± 1.3"* 88 ± 4.8** 284 ± 9.7** 

/zg Ni/g lung -- 42 ± 2.8** 108 ± 4.3** 267 ± 12.3"* 

~g Ni/g control lung -- 42 ± 1.6"* 103 ± 5.6** 331 ± 11.4"* 

Female 

Absolute lung wt (g) 0.739 ± 0.028 0.704 ± 0.017 0.731 ± 0.040 0.861 ± 0.025* 

#g Ni/lung -- 38 ± 4.8** 88 ± 3.3** 293 ± 13.4"* 

~g Ni/g lung -- 54 ± 5.7** 122 ± 10.3"* 340 ± 10.4"* 

~g Ni/g control lung -- 52 ± 6.5** 119 ± 4.5** 396 5: 18.2"* 

* Significantly different (P_<0,05) from the control group by Dunnett's test (lung weight) or Shirley's test (lung burden parameters) 

** P~0.01 

a Mean ± standard error 

b Results were below 0.182 ~g Ni (the limit of detection), or below the level of quantitation. 
52 Nickel Oxide, NTP TR 451 

13-WEEK STUDY 

One male rat exposed to 2.5 mg nickel oxide/m 3 died 

during week 3 of the study; this death was not 

considered to be exposure related (Table 8). Final 

mean body weights and mean body weight gains of 

exposed males and females were similar to those of 

the controls. There were no consistent clinical 

findings in any group that were related to nickel 

oxide exposure. 

TABLE 8 

Survival and Body Weights of Rats in the 13-Week Inhalation Study of Nickel Oxide 

Dose Survival a Initial 

(mg/m a) 

Mean Body Weight b (g) Final Weight 

Final Change Relative to Controls 

(%) 

Male 

0 10/10 

0.6 10/10 

1.2 10/10 

2.5 9/10 c 

5 10/10 

10 10/10 

128 ± 3 

132 ± 4 

130 ± 4 

131 ± 4 

130 ± 4 

127 ± 3 

306 ± 7 179 ± 5 

317 ± 6 185 ± 6 103 

319 ± 7 189 ± 5 104 

303 ± 6 171 ± 5 99 

314 ± 5 184 ± 6 102 

308 ± 6 181 ± 5 100 

Female 

0 10/10 110 ± 3 190 ± 5 80 ± 3 

0.6 10/10 112 ± 3 192 ± 3 80 ± 3 101 

1.2 10/10 106 ± 2 193 ± 3 87 ± 4 101 

2.5 10/10 107 ± 3 186 ± 4 79 :k 3 98 

5 10/10 100 ± 3 187 ± 4 87 ± 3 98 

10 10/10 110 ± 3 190 ± 4 81 ± 3 100 

a Number of animals surviving at 13 weeks/number initially in group 

b Weights and weight changes are given as mean ± standard error. Subsequent calculations are based on animals surviving to the end of 

the study. Differences from the control group were not significant by Dunnett's test. 

c Week of death: 3 
Results 53 

Hematology results are presented in Table G1. In 

general, there were minimal to mild differences, and 

females were affected more than males. A mature 

neutrophilia was indicated by greater segmented 

neutrophil counts in 1.2, 2.5, 5, and 10 mg/m 3 males 

and all exposed females. Monocyte counts in 2.5, 5, 

and 10 mg/m 3 females were mildly greater than that 

in the controls. There was microscopic evidence of 

chronic active pulmonary inflammation in 2.5, 5, 

and 10mg/m 3 males and females, and this could 

account for the neutrophilia and monocytosis. 

Increased tissue demand for granulocytes due to 

inflammation causes increased bone marrow production and release and can increase the intravascular 

life span of neutrophils resulting in neutrophilia. 

Monocytosis can also result from inflammation, 

particularly a chronic inflammatory process. However, neutrophilia occurred at exposure concentrationsat which no microscopic evidence of inflammation was seen. Thus, mechanisms that alter 

granulopoiesis and/or rate of release from the bone 

marrow, redistribute neutrophils between the 

marginal and the circulating pools, or increase the 

intravascular neutrophil life span could be considered. Lymphocytosis was indicated by lymphocyte .counts in 2.5, 5, and 10 mg/m 3 females that 

were greater than that in the controls. The lymphocytosis may be a reflection of the bronchial and 

mediastinal lymph node hyperplasia observed in 

these exposure groups. However, stimulation of 

lymphopoiesis may not result in lymphocytosis, and 

other mechanisms altering lymphocyte margination 

or homing, tissue migration, and recirculation may 

be involved. Total leukocyte counts in 1.2 and 

10mg/m 3 males and in females exposed to 

1.2 mg/m 3 or higher were greater than those in the 

controls and were a reflection of the increased 

neutrophil, lymphocyte, and monocyte counts. 

Hematocrit, hemoglobin concentration, and erythrocyte counts in 10 mg/m 3 males and in most exposed 

groups of females were minimally to mildly greater 

than those in the controls. These differences were 

accompanied by mean cell volumes in 5 mg/m 3 

males and in 1.2 mg/m 3 and higher females that were 

minimally less than those in the controls. Mean cell 

hemoglobin concentrations in 2.5 mg/m 3 males and 

all exposed groups of females were minimally 

greater than those in the controls. Increases in mean 

cell hemoglobin concentration have been related to 

erythrocyte hemolysis (in vivo or in vitro), alterations 

in the hemoglobin concentration or hematocrit, or an 

artifact (e.g., lipemia, Heinz bodies). The higher 

hematocrit values, hemoglobin concentrations, and 

erythrocyte counts could be consistent with dehydration (relative erythrocytosis) or with increased 

erythropoietin production as the result of tissue 

hypoxia (secondary erythrocytosis). Secondary 

erythrocytosis has been observed with pulmonary or 

cardiovascular disease, altered erythrocyte/ 

hemoglobin oxygen transport, and reduced atmospheric oxygen. In this study.~ pulmonary lesions 

were observed microscopically in 2.5, 5, and 

10 mg/m 3 males and females, and this could account 

for the increases observed. Lower mean cell volume 

has been associated with metabolic alterations related 

to iron, copper, and pyridoxine deficiency. Total 

nucleated erythrocyte counts in 5 mg/m 3 males and 

all exposed females were greater than those in the 

controls. Reticulocyte counts were not affected, and 

this is consistent with mild relative erythrocytosis or 

with a very mild increase in erythropoiesis. Differences in nucleated erythrocyte counts were not 

accompanied by anemia or by corresponding differences in reticulocyte counts. Nickel is a transition 

metal, as are cobalt and iron. Excess cobalt can 

induce erythrocytosis, due to increased erythropoietin 

production, and iron is essential for heme synthesis. 

Thus, the presence of excess nickel may have altered 

normal biological activities associated with transition 

metals and could account for some of the differences 

that occurred (e.g., the minimal erythrocytosis and 

lower mean cell volume). 

Sperm concentration in 10 mg/m 3 males was significantly lower than that in controls (Table Jl). There 

were no significant differences in vaginal cytology 

between control and exposed females. 

Absolute and relative lung weights of all exposed 

groups of rats (except absolute lung weight of 

0.6 mg/m 3 females) were significantly greater than 

those of controls (Table F2). Other organ weight 

differences were considered incidental and unrelated 

to nickel oxide exposure. Chemical-related lesions 

in the lung and in the bronchial and mediastinal 

lymph nodes were identified through gross examination at necropsy. When the thoracic cavity was 

opened, the lungs of rats exposed to 10 mg/m 3 failed 

to collapse to the extent typically observed in control 
54 Nickel Oxide, NTP TR 451 

animals. Multiple pale or white foci, 1 to 2 mm in 

diameter, were scattered throughout the lung parenchyma in one or more male rats in each exposure 

group and in most male and female rats exposed to 

2.5, 5, or 10 mg/m 3. These lung foci were generally 

fewer in number and smaller at lower exposure 

concentrations. The lymph nodes associated with the 

respiratory tract were enlarged in most male and 

female rats exposed to 5 or 10 mg/m 3. 

Chemical-related histopathologic lesions were present 

in the lung and in the lymph nodes associated with 

the respiratory tract of exposed males and females 

(Table 9). The lymph node enlargement was 

TABLE 9 

Incidences of Selected Nonneoplastic Lesions in Rats in the 13-Week Inhalation Study of Nickel Oxide 

0 mg/m 3 0.6 mg/m 3 1.2 mg/m 3 2.5 mg/m 3 5 mg/m 3 10 mg/m 3 

Male 

Lung a 10 10 10 9 10 10 

Alveolar Macrophage Hyperplasia b 0 10"* (1.0) c 10"* (1.0) 9** (1.0) 10"* (1.5) 10"* (2.5) 

Inflammation, Chronic Active 0 0 0 2 (1.0) 10"* (1.4) 10"* (3.0) 

Inflammation, Granulomatous 0 0 0 0 3 (2.0) 2 (3.0) 

Interstitial Infiltrate 0 0 1 (1.0) 2 (1.0) 10"* (1.4) 10"* (2.1) 

Pigment 0 6** (1.0) 7** (1.0) 9** (1.0) 9** (1.0) 10"* (1.8) 

Lymph Node, Bronchial 8 9 10 8 10 10 

Hyperplasia 0 0 0 2 (1.0) 9** (1.6) 10"* (2.7) 

Pigment 0 0 0 7** (1.0) 10"* (1.0) 10"* (1.0) 

Lymph Node, Mediastinal 9 8 8 8 10 10 

Hyperplasia 0 0 0 2 (1.0) 5* (1.4) 10"* (2.5) 

Pigment 0 0 0 4* (1.0) 6** (1.0) 5* (1.0) 

Female 

Lung 10 10 10 10 10 10 

Alveolar Macrophage Hyperplasia 0 10"* (1.0i 8** (1.0) 10"* (1.0) 10"* (1.4) 10"* (2.2) 

Inflammation, Chronic Active 0 0 0 1 (I.0) 7** (1.3) 7** (2.7) 

Inflammation, Granulomatous 0 0 0 0 4* (2.1) 4* (2.0) 

Interstitial Infiltrate 0 0. 0 2 (1.0) 10"* (1.2) 10"* (1.8) 

Pigment 0 0 4* (1.0) 8** (1.0) 8** (1.0) 10"* (1.2) 

Lymph Node, Bronchial 7 7 10 7 10 10 

Hypetplasia 0 0 0 0 8** (1.5) I0"* (2.6) 

Pigment 0 0 0 4* (1.0) 8** (1.0) 10"* (1.0) 

Lymph Node, Mediastinal 9 9 8 10 9 10 

Hyperplasia 0 0 0 1 (1.0) 5* (1.4) 9** (2.2) 

Pigment 0 0 0 2 (1.0) 9** (1.0) 8** (1.0) 

* Significantly different (P ~0.05) from the control group by the Fisher exact test 

** P~0.01 

a Number of animals with organ examined microscopically 

b Number of animals with lesion 

c Average severity of lesions in affected animals: 1 = minimal; 2 = mild; 3 = moderate; 4 = marked 
Results 55 

attributed to lymphoid hyperplasia characterized by 

an increase in the number of lymphocytes, primarily 

in the paracortical areas of the lymph nodes. 

Lymphoid hyperplasia was commonly present in rats 

exposed to 5 or 10 mg/m 3 and also occurred in a few 

2.5 mg/m 3 rats. Densely stained black pigment 

particles and aggregates of these pigment particles 

were present in the lymph nodes of males and 

females exposed to 2.5, 5, or 10 mg/m 3. There 

were exposure-related inflammatory lesions and 

pigment in the lungs of males and females. At the 

lower exposures of 0.6, 1.2, and 2.5 mg/m 3, there 

was only a minimally detectable increase in the 

number of macrophages within the alveoli; minimal 

interstitial or chronic active inflammation was 

present in a few rats. Pigment particles were present 

in the cytoplasm of alveolar macrophages as well as 

extracellularly within the alveolar spaces. At 5 and 

10 mg/m 3, the severity and spectrum of 

inflammatory changes in the lung were increased. 

Inflammatory lesions included minimal to mild 

interstitial infiltrates of lymphocytes around blood 

vessels and chronic active inflammation characterized 

by a mild thickening of alveolar septa with a mixture 

of neutrophils and mononuclear inflammatory cells. 

Adjacent to these foci of inflammation, type II cells 

were often enlarged. Granulomatous inflammation 

also occurred in a few rats and consisted of larger, 

focal aggregates of epithelioid macrophages within 

the alveoli or interstitial areas. 

At 4 and 9 weeks and at the end of the 13-week 

study, nickel concentrations in the lung of 0.6, 2.5, 

and 10 mg/m 3 males were significantly greater than 

those in the controls, and the nickel concentrations 

increased with exposure concentration (Tables 10 

and H3). At 13 weeks, the absolute lung weights of 

2.5 and 1.0 mg/m 3 males were significantly greater 

than that of the controls. 

TABLE 10 

Lung Weight and Lung Burden in Male Rats in the 13-Week Inhalation Study of Nickel Oxide a 

0 mg/m 3 0,6 mg/m 3 2.5 mg/m 3 10 mg/m ~ 

n 6 

4 weeks 

b #g Ni/g lung -- 

6 6 6 

33 ± 2.3** 110 ± 6.6** 263 ± 18.5"* 

9 weeks 

#g Ni/g lung -- 53 ± 6.8** 143 ± 27.9** 400 ± 31.2"* 

13 weeks 

Absolute lung wt (g) 0.954 5:0.043 1.082 ± 0.028 1.534 ± 0.032** 2.108 ± 0.097** 

#g Ni/lung -- 86 5: 6.0** 276 ± 34.6** 1,092 ± 63.1"* 

#g Ni/g lung -- 80 ± 5.5** 181 ± 25.6** 524 ± 38.2** 

~g Ni/g control lung -- 91 ± 6.3** 289 ± 36.3** 1,146 ± 66.2** 

** Significantly different (P_<0.01) from the control group by Williams' test (lung weight) or Shirley's test (lung burden parameters) 

a Mean ± standard error 

O Results were below 0.301 /ug Ni (the limit of detection), or below the level of quanfitation. 

Dose Selection Rationale: Based on the increased 

severity and wider spectrum of inflammatory lesions 

of the lung and increased lung weights in males and 

females exposed to 5 and 10 mg/m 3 in the 13-week 

study, nickel oxide exposure concentrations selected 

for the 2-year inhalation study in rats were 0.62, 

1.25, and 2.5 mg/m 3. 
56 Nickel Oxide, NTP TR 451 

2-YEAR STUDY 

Survival • . 

Estimates of 2-~ear survival probabilities for male 

and female rats are shown in Table 11 and in the 

Kaplan-Meier survival curves in Figure 2. Survival 

of exposed male and female rats was similar to that 

of the controls. 

TABLE 11 

Survival of Rats in the 2-Year Inhalation Study of Nickel Oxide 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 

Male 

Animals initially in study 65 65 65 65 

7-Month interim evaluation a 6 7 7 7 

15-Month interim evaluation a 5 5 5 5 

Missexed a 0 0 0 1 

Moribund 39 35 32 36 

Natural deaths 1 3 6 4 

Animals surviving to study termination 14 15 15 e 12 e 

Percent probability of survival at end of study b 26 28 28 23 

Mean survival (days) c 592 594 582 582 

Survival analysis d P=0.563 P=0.772N P= 1.000N P=0.720 

Female 

Animals initially in study 65 65 65 65 

7-Month interim evaluation a 7 7 7 6 

15-Month interim evaluation a 5 5 5 5 

Moribund 27 24 27 25 

Natural deaths 5 3 6 3 

Animals surviving to study termination '21 26 20 26 

Percent probability of survival at end of study 40 49 38 48 

Mean survival (days) 594 607 592 597 

Survival analysis P=0.834N P=0.392N P=0.921 P=0.657N 

a Censored from survival analyses 

b Kaplan-Meier determinations based on the number of animals alive on the first day of terminal sacrifice 

c Mean of all deaths (uncensored, censored, and terminal sacrifice) 

d The result of the life table trend test (Tarone, 1975) is in the control column, and the results of the life table pairwise comparisons (Cox, 

1972) with the controls are in the exposed columns. A negative trend or a lower mortality in an exposure group is indicated by N. 

e Includes one animal that died during the last week of the study. 
Results 57 

0 

0.4 .... MALE RATS ........ ........... ; ............................. i .......................... 

[.o./,,~ I • ~ :: :: L:: 

| I o o.ez-,o/us I " " : ! ~! 

o..sl I ~ ,.,s,.~/~ I ........... ~ .......... ~ ...... ~ ................ 

I ° '''~*"' I ~ ~ 

0.9. 

0.2- 

0 I ~ Z~O 455 60 7 ~ 90 1055 

WEEKS ON STUDY 

120 

0.9- 

0.a0.7- 

0.0- 

0.S0.4' 

0,3  ̧ 

0.2 

0 

: : : : t 

'1 . .~ ............. ~ ............... : ................. ~ ................. I~. . ~b . ~ ~ 

I ! i i!i l ' 

• 

! 5 ~ ,~ ~0 ~$ ~0 ~ ~ ~ ~ 

WEEKS ON SIUDY 

FIGURE 2 

Kaplan-Meier Survival Curves for Rats Administered Nickel Oxide by Inhalation for 2 Years 
58 Nickel Oxide, NTP TR 451 

Body Weights and Clinical Findings 

Mean body weights of males and females exposed to 

0.62 mg/m 3 and males exposed to 1.25 mg/m 3 were 

similar to those of the controls throughout the study 

(Figure 3 and Tables 12 and 13). Mean body 

weights of females exposed to 1.25 mg/m 3 and males 

and females exposed to 2.5 mg/m 3 were slightly less 

than those of the controls during the second year of 

the study. No chemical-related clinical findings were 

observed in male or female rats during the 2-year 

study. 

Hematology 

No chemical-related differences in hematology 

parameters were observed in male or female rats at 

the 15-month interim evaluation (Table G2). 
Results 59 

< 

Z 

taJ 

0 

m 

Z 

5,50 

500 

450 - 

.................. ! ..................... ~ .................... :: ................ li +,+:"++, .......... " ......... + .................... 

!tt I + I : ! ..................... : I + ........... + ..... !+: i" 

,. ................. +. i.++ I ' ........ ~ .............................. i. ~.. 

350 - ! ........................................ : .................... .................. + ..................... : ..................... 

. : 

: 

: 

300 ............................ + ........................................ :~ ............................................................... 

! + MALE RATS 

+ 

2,50 ................................ i ..................................... ; ................ • 0 MO/M$ 

200 ............... : .... 

1 50- 

100 / 

0 1 5 ;to 45 ~'o 

WEEKS ON STUDY 

0 o +/.s 

~ o.~ ~o~ 

I~ o.+2 ~/MS 

• o.ls m<3/us 

,O. I.~'". ~G[~$ 

~ ~.~ ~o/~ 

& z.5 ~G/~3 

~ ~ 

A + ,os 

Z 

w 

0 

Z 

550 - 

500 ................... .................. i ........... 

i i : 

: 

450 ................ : ........... i ............. ! ................. : .................................................. 

, 

: + 

400 ....................... ....................................... ................. 

350 .................... : .................. + .................... ! ....................................................................... I"I' 

, :: + _ i I :l n II I I 

300 ................... i ..................... i ................... ! ...... ~ ~ ~. ~* * ~ ~ ~ ~ ~ 

+ .................. + ....... ,-,""'"' ....... ................. " 

~ ~ • 

; ; ~.~ ~]~ 200- . ~ ..... ............ ................. .. 

~ : ~ ~.zs ~1~+ 

~ * ~.~ ~1.~ 

150- ~ ......... ~ ~++mo/m+ .. [ ~ 2.5 too/m+ 

+ : ~ 

I00 

1+ + 45 60 75 + ,05 

WEEKS ON STUDY 

FIGURE 3 

Growth Curves for Rats Administered Nickel Oxide by Inhalation for 2 Years 
60 Nickel Oxide, NTP TR 451 

TAnLE 12 

Mean Body Weights and Survival of Male Rats in the 2-Year Inhalation Study of Nickel Oxide 

Weeks 0 mg/m s 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 

on Av. Wt. No. of Av. Wt. Wt. (% of No. of Av.Wt. Wt. (% of No. of Av. Wt. Wt. (% of No. of 

Study (g) Survivors (g) controls) Survivors (g) controls) Survivors (g) controls) Survivors 

1 143 65 141 98 65 141 99 65 142 99 65 

2 193 65 189 98 65 193 100 65 191 99 65 

3 219 65 216 99 65 222 102 65 216 99 65 

4 241 65 240 100 65 241 100 65 237 98 64 

5 257 65 259 101 65 258 100 65 254 99 64 

6 274 65 276 101 65 276 101 65 273 100 64 

7 284 65 288 102 65 287 101 65 283 100 64 

8 297 65 299 101 65 301 101 65 296 100 64 

9 306 65 307 100 65 308 101 65 304 99 64 

10 316 65 318 101 65 320 101 65 315 100 64 

11 324 65 327 101 65 326 101 65 321 99 64 

12 333 65 336 101 65 335 101 65 332 100 64 

13 340 65 340 100 65 339 100 65 337 99 64 

17 368 65 366 100 65 366 100 65 362 98 64 

21 385 65 382 99 65 384 100 65 378 98 64 

25 401 65 398 99 65 399 99 65 394 98 64 

29 a 411 58 406 99 58 402 98 58 397 96 57 

33 432 58 421 98 58 424 98 57 416 96 57 

37 451 58 438 97 58 442 98 57 433 96 57 

41 461 58 446 97 58 453 98 57 442 96 57 

45 470 58 455 97 58 462 98 57 450 96 57 

49 481 58 462 96 58 471 98 57 460 96 57 

53 478 58 459 96 58 466 98 56 457 96 57 

57 490 58 471 96 58 478 98 56 464 95 57 

61 494 58 476 96 58 484 98 56 469 95 57 

65 500 58 482 96 58 489 98 56 473 95 57 

69 a 499 52 481 96 52 494 99 50 473 95 49 

73 499 50 478 96 51 488 98 50 468 94 49 

77 501 49 477 95 48 487 97 48 465 93 48 

81 489 49 468 96 45 482 99 45 458 94 43 

85 487 40 469 96 41 480 99 '39 456 94 37 

89 471 37 464 99 38 466 99 33 449 95 33 

93 477 30 464 97 32 461 97 28 448 94 28 

97 460 26 445 97 30 442 96 26 436 95 20 

101 449 18 449 100 20 428 95 20 417 93 18 

Mean for weeks 

1-13 271 272 100 273 101 269 99 

14-52 429 419 98 423 99 415 97 

53-101 484 468 97 473 98 456 94 

a Interim evaluations occurred during weeks 29 and 66. 
Results 61 

TABLE 13 

Mean Body Weights and Survival of Female Rats in the 2-Year Inhalation Study of Nickel Oxide 

Weeks 0 mg/m ~ 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m ~ 

on Av. Wt. No. of Av. Wt. Wt. (% of No. of Av. Wt. Wt. (% of No. of Av. Wt. Wt. (% of No. of 

Study (g) Survivors (g) controls) Survivors (g) controls) Survivors (g) controls) Survivors 

1 115 65 115 100 65 114 99 65 114 99 65 

2 140 65 139 99 65 139 99 65 137 98 65 

3 153 65 151 99 65 151 99 65 149 97 65 

4 163 65 161 99 65 159 98 65 159 98 65 

5 169 65 168 99 65 165 98 65 167 . 99 65 

6 179 65 176 99 65 174 97 65 176 99 65 

7 181 65 181 100 65 177 98 65 180 99 65 

8 188 65 187 99 65 185 98 65 186 99 65 

9 191 65 189 99 65 187 98 65 187 98 65 

10 195 65 194 99 65 193 99 65 192 99 65 

11 200 65 199 100 65 195 98 65 194 97 65 

12 202 65 202 100 65 201 99 65 200 99 65 

13 205 65 204 99 65 202 98 65 203 99 65 

17 217 65 215 99 65 211 97 65 213 98 64 

21 226 65 223 99 65 218 97 65 221 98 64 

25 237 65 233 98 65 230 97 65 233 98 64 

29 a 239 58 237 99 58 231 96 58 235 98 58 

33 248 58 243 98 58 238 96 58 243 98 58 

37 260 58 255 98 58 250 96 58 253 97 58 

41 270 58 265 98 58 260 96 58 265 98 58 

45 278 58 276 99 58 271 97 58 272 98 58 

49 289 58 286 99 58 279 96 58 283 98 58 

53 296 56 292 99 58 287 97 57 287 97 58 

57 304 56 301 99 58 297 98 57 297 98 58 

61 314 55 308 98 57 305 97 57 303 96 58 

65 323 55 315 98 57 311 96 56 309 96 58 

69 a 330 48 318 97 50 314 95 48 313 95 51 

73 335 48 321 96 49 316 95 46 313 94 49 

77 336 48 325 97 45 320 95 44 314 94 48 

81 338 44 326 97 45 323 95 43 314 93 44 

85 341 42 332 97 45 325 95 42 315 92 41 

89 341 39 330 97 43 323 95 39 316 93 37 

93 341 34 331 97 39 325 95 32 316 93 35 

97 345 31 332 96 33 319 93 31 312 91 31 

101 344 28 330 96 32 316 92 26 308 90 29 

Mean for weeks 

1-13 175 174 99 172 98 173 99 

14-52 252 248 98 243 96 246 98 

53-101 330 320 97 314 95 309 94 

a Interim evaluations occurred during weeks 29 and 66. 
62 Nickel Oxide, NTP TR 451 

Pathology and Statistical Analyses 

This section describes the statistically significant or 

biologically noteworthy changes in the incidences of 

nonneoplastic lesions of the lung, lymph nodes, and 

adrenal medulla and neoplasms of the lung and 

adrenal medulla. Summaries of the incidences of 

neoplasms and nonneoplastic lesions, individual 

animal tumor diagnoses, statistical analyses of 

primary neoplasms that occurred with an incidence 

of at least 5 % in at least one animal group, and 

historical incidences for the neoplasms mentioned in 

this section are presented in Appendix A for male 

rats and Appendix B for female rats. 

Lung: Absolute and relative lung weights of males 

exposed to 1.25 or 2.5 mg/m 3 and of exposed 

females were significantly greater than those of the 

controls at 7 months (Table F3). At 15 months, 

absolute and relative lung weights of males and 

females exposed to 1.25 or 2.5 mg/m 3 were significantly greater than those of the controls (Table F4). 

At 2 years, the incidence of alveolar/bronchiolar 

carcinoma in 1.25 mg/m 3 females was significantly 

greater than that of the controls (Tables 14 and B3). 

There are no incidences of alveolar/bronchiolar 

carcinoma in historical control females from inhalation studies, and the incidence in the 1.25 mg/m 3 

females exceeds the historical control range from 

feed studies (Tables 14 and B4a). There were 

exposure-related increases in the incidences of 

alveolar/bronchiolar adenoma or carcinoma (combined) in males and females. The incidences of 

alveolar/bronchiolar adenoma or carcinoma (c6mbined) in 1.25 mg/m 3 males and females and 

2.5 mg/m 3 females exceeded historical control ranges 

from inhalation studies (Tables 14, A4a, and B4a). 

Alveolar/bronchiolar carcinomas had neoplastic cells 

arranged in mixtures of alveolar, papillary, and 

tubular structures, and the cells often formed 

multiple layers or solid clusters. A few carcinomas 

contained small to moderate amounts of dense 

fibrous tissue (scirrhous reaction ). A few carcinomas, particularly those with scirrhous reaction, had 

large, moderately to highly pleomorphic cells. 

Carcinomas with squamous differentiation consisted 

of a mixture of an alveolar/bronchiolar epithelial 

component and a stratified squamous epithelial 

component (Plate 1). These carcinomas presumably 

originated from the alveolar/bronchiolar epithelium, 

and the stratified squamous epithelial component 

arose through squamous differentiation. The stratified squamous component in five of these alveolar/ 

bronchiolar carcinomas in exposed rats was the 

predominant component, highly proliferative, and 

clearly neoplastic. This pronounced squamous 

component is not typical of alveolar/bronchiolar 

carcinomas arising spontaneously in nonexposed rats; 

however, the fibrous tissue component and the 

squamous differentiation observed in some of these 

neoplasms have also been observed in rats in other 

studies of inhaled particulates (e.g. talc; NTP, 

1993a). Alveolar/bronchiolar adenoma consisted of 

relatively uniform simple cuboidal or columnar 

epithelium arranged in papillary or pseudoalveolar 

patterns that focally distorted or replaced normal 

alveolar architecture (Plate 2). Adenomas were 

usually visible macroscopically in histopathologic 

specimens. The severity of the inflammatory alterations in the lungs of exposed rats obscured the gross 

identification of most of these neoplasms at 

necropsy. 

One male and one female rat exposed to 2.5 mg/m 3 

had a squamous cyst, and there was one instance of 

squamous metaplasia in the lung of a 0.62 mg/m 3 

male (Tables 14, A5, and B5). A squamous cyst has 

a well-differentiated, stratified squamous, epithelial 

wall and a central lumen containing keratin. Squamous metaplasia in the lung is the focal replacement 

of alveolar pneumocytes by well-differentiated 

squamous epithelium. 

The incidence of atypical alveolar epithelial hyperplasia generally increased with exposure concentration in males and females at 2 years. Both focal and 

atypical alveolar epithelial hyperplasias were considered a part of the morphologic continuum toward 

neoplasia. Focal alveolar epithelial hypelrplasia 

consisted of foci where basophilic cuboidal epithelial 

cells, rather than type I cells, lined alveolar septa 

that maintained normal architecture. Atypical 

alveolar epithelial hyperplasia consisted of focal 

hyperplasia in which lining cells had increased 

basophilia and less uniformity in size, shape, and 

alignment. Some hyperplasias occurred near foci of 

inflammation, but the hyperplasia extended a considerable distance away from the inflammation; these 

were considered to be a chemical-related effect 

separate from the inflammation. 
Results 63 

TABLE 14 

Incidences of Neoplasms and Nonneoplastic Lesions of the Lung in Rats in the 2-Year Inhalation Study 

of Nickel Oxide 

0 mg/m a 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 

Male 

7-Month Interim Evaluation 

Lung a 6 7 7 7 

Inflammation, Chronic b 3 (1.0) c 0 7 (2.0) 7 (1.7) 

Alveolus, Pigmentation 0 6** (1.0) 7** (1.0) 6** (1.0) 

15-Month Interim Evaluation 

Lung 5 5 5 5 

Inflammation, Chronic 4 (1.0) 5 (1.0) 5 (2.2) 5 (2.2) 

Alveolus, Pigmentation 0 5** (1.0) 5** (1.2) 5** (2.0) 

2-Year Study 

Lung 54 53 53 52 

Inflammation, Chronic 28 (1.1) 53** (1.6) 53** (2.1) 52** (2.6) 

Alveolar Epithelium, Hyperplasia, 

Focal or Atypical 0 2 (2.0) 5 (1.8) 0 

Alveolar Epithelium, 

Squamous Metaplasia 0 1 (1.0) 0 0 

Alveolus, Pigmentation 1 (1.0) 53** (1.3) 53** (1.8) 52** (2.1) 

Squamous Cyst 0 0 0 1 

Alveolar/bronchiolar Adenoma 0 1 3 2 

Alveolar/bronchiolar Carcinoma, 

Squamous Differentiation 0 

Alveolar/bronchiolar Carcinoma 

(Includes Squamous Differentiation) 0 

Alveolar/bronchiolar Adenoma 

or Carcinoma 0 

0 2 0 

0 3 2 

1 6* 4* 

Squamous Cell Carcinoma 0 0 0 

Alveolar/bronchiolar Adenoma or Carcinoma or Squamous Cell Carcinoma d 

Overall rate e 1/54 (2%) 1/53 (2%) 

Adjusted rate f 7.1% 2.6% 

Terminal rate g 1/14 (7%) 0/15 (0%) 

First incidence 733 (T) 623 

Logistic regression test h P=0.062 P=0.760N 

Female 

7-Month Interim Evaluation 

Lung 7 7 

Inflammation, Chronic 1 (1.0) 0 

Alveolus, Pigmentation 0 5* (1.o) 

(continued) 

6/53 (11%) 

27.7% 

3/15 (20%) 

567 

P=0.054 

7 

7** (1.1) 

7** (1.0) 

4/52 (8 %) 

23.7% 

2/12 (17%) 

633 

P=O.141 

6 

6** (1.0) 

6** (1.0) 
64 Nickel Oxide, NTP TR 451 

TABLE 14 

Incidences of Neoplasms and Nonneoplastic Lesions of the Lung in Rats in the 2-Year Inhalation Study 

of Nickel Oxide (continued) 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 

Female (continued) 

15-Month Interim Evaluation 

Lung 5 

Inflammation, Chronic 3 (1.0) 

Alveolus, Pigmentation 0 

2-Year Study 

Lung 53 

Inflammation, Chronic 18 (1.1) 

Alveolar Epithelium, Hyperplasia, 

Focal or Atypical 2 (2.0) 

Alveolus, Pigmentation 0 

Squamous Cyst 0 

Alveolar/bronchiolar Adenoma 

(Multiple) 0 

Alveolar/bronchiolar Adenoma 

(Single or Multiple) 1 

Alveolar/bronchiolar Carcinoma, 

Squamous Differentiation 0 

Alveolar/bronchiolar Carcinoma 

(Includes Squamous Differentiation) 0 

Alveolar/bronchiolar Adenoma or Carcinoma i 

Overall rate 1/53 (2%) 

Adjusted rate 4.8% 

Terminal rate 1/21 (5%) 

First incidence 729 (T) 

Logistic regression test P=0.022 

5 5 5 

4 (1.0) 5 (2.2) 5 (2.4) 

5** (1.0) 5** (1.2) 5** (1.2) 

53 53 54 

52** (1.7) 53** (2.4) 54** (2.4) 

1 (2.0) 6 (2.5) 6 (1.5) 

52** (1.7) 53** (2.1) 54** (2.0) 

0 0 1 

0 0 1 

0 1 4 

0 2 1 

0 5* 1 

0/53 (0%) 6/53 (11%) 5/54 (9%) 

0.0% 24.7% 19.2% 

0/26 (0%) 4/20 (20%) 5/26 (19%) 

--J 643 729 (T) 

P=0.457N P=0.053 P=0.152 

(T)Terminal sacrifice 

* Significantly different (P_<0.05) from the control group by the Fisher exact test (interim evaluations) or the logistic regression test 

(2-year study) 

** P_<0.01 

a Number of animals with lung examined microscopically 

b Number of animals with lesion 

e Average severity grade of lesions in affected animals: 1 = minimal, 2 = mild, 3 = moderate, 4 = marked 

d Historical incidence for 2-year NTP inhalation studies with untreated control groups (mean ± standard deviation): 27/703 

(3.8% ± 3.8%); range 0%-10%. Feed studies: 39/1,200 (3.3% ± 2.0%); range 0%-8% 

e Number of animals with neoplasm per number of animals with lung examined microscopically 

f Kaplan-Meier estimated neoplasm incidence at the end of the study after adjustment for intercurrent mortality 

g Observed incidence in animals surviving until the end of the study 

h In the control column are the P values associated with the trend test. In the exposure group columns are the P values corresponding to 

the pairwise comparisons between the controls and that exposure group. The logistic regression test regards lesions in animals dying 

prior to terminal kill as nonfatal. A lower incidence in an exposure group is indicated by N. 

i Historical incidence for 2-year NTP inhalation studies: 8/700 (1.1% ± 1.5%); range 0%-4% (includes squamous cell carcinoma). Feed 

studies: 25/1,201 (2.1% ± 2.2%); range 0%-10% 

J Not applicable; no neoplasms in animal group 
Results 65 

Chronic inflammation of the lung was observed in 

most exposed animals at 7 and 15 months and at 

2 years, and the incidences in exposed males and 

females at 2 years were significantly greater than 

those in the controls (Tables 14, A5, and B5). The 

incidences of pigmentation in the alveoli of exposed 

groups of males and females were significantly 

greater than those of the controls at 7 and 15 months 

and at 2 years. The severity of this pigmentation 

generally increased with increasing exposure concentration. Pigmentation in the lungs of exposed rats 

was finely granular and black. It was clearly related 

to nickel oxide exposure and could be differentiated 

from the occasional coarser granules of endogenous 

golden brown to greenish-brown hemosiderin pigment. In exposed rats, most or all alveolar lumens 

contained small to moderate amounts of eosinophilic 

granular material or irregular aggregates of homogeneous eosinophilic material (proteinosis), and in 

some lungs this eosinophilic material was the predominant component of the inflammation. 

Chronic inflammation also included alveolar macrophages scattered within the lumens of many alveoli 

(Plate 3). The number of alveoli containing macrophages and the number of macrophages within 

alveoli increased with increasing severity of inflammation. Some alveolar macrophages resembled those 

normally seen in the lung, but most were enlarged 

with a moderate to abundant amount of pale vacuolated cytoplasm. Multiple focal clusters of alveoli 

filled with accumulations of inflammatory cells 

(macrophages sometimes mixed with small to moderate numbers of neutrophils) and debris were seen 

commonly, often in the periphery of the lobes 

adjacent to the pleural surface. Hyperplasia of 

alveolar epithelial cells (presumably of type II cells) 

was usually seen in alveoli containing inflammatory 

exudate, and was not diagnosed separately since it, 

was a regenerative response secondary to the inflammation. Varying amounts of parenchymal and 

subpleural fibrosis were present within these inflammatory foci and, in some cases, the fibrosis was 

severe and had replaced much of the alveolar structure. Clear slit-like spaces, resembling cholesterol 

clefts, were sometimes present within the areas of 

fibrosis. Chronic inflammation also included one or 

more small discrete focal clusters of alveoli containing small to moderate numbers of macrophages, 

occasionally mixed with a few neutrophils, and lined 

by hyperplastic epithelium. The extent, diversity, 

and intensity of the inflammatory alterations in the 

lungs of exposed rats were clearly distinguishable 

from those in the lungs of control rats. 

Bronchial Lymph Node: Pigmentation in the 

bronchial lymph nodes similar to that in the lungs 

was observed in all exposure groups with the exception of 0.62 mg/m 3 males and females at 7 months 

(Tables 15, A5, and B5). As in the lung, the finely 

granular, black pigment in the bronchial lymph 

nodes was clearly related to nickel oxide exposure. 

Lymphoid hyperplasja was observed in the bronchial 

lymph nodes of 1.25 and 2.5 mg/m 3 males and 

females at 7 and 15 months, and the incidence at 

2 years generally increased with exposure concentration. Lymphoid hyperplasia consisted of an 

increased number of cortical lymphocytes, often 

accompanied by enlargement of the lymph node. 

The lymphocytes were at different stages of differentiation and the overall architecture of the lymph node 

was maintained. 
66 Nickel Oxide, NTP TR 451 

TABLE 15 

Incidences of Nonneoplastic Lesions of the Bronchial Lymph Node in Rats 

in the 2-Year Inhalation Study of Nickel Oxide 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 

Male 

7-Month Interim Evaluation 

Lymph Node, Bronchial a 6 7 7 7 

Hyperplasia, Lymphoid b 1 (1.0) c 0 7** (1.3) 4 (1.3) 

Pigmentation 0 0 7** (1.0) 7** (1.0) 

15-Month Interim Evaluation 

Lymph Node, Bronchial 5 5 5 5 

Hyperplasia, Lymphoid 0 0 4* (1.3) 4* (1.0) 

Pigmentation 0 5** (1.0) 5** (1.2) 5** (1.4) 

2-Year Study 

Lymph Node, Bronchial 52 51 53 52 

Hyperplasia, Lymphoid 0 7* (1.7) 10"* (1.8) 18"* (1.6) 

Pigmentation 0 45** (1.4) 51"* (1.8) 51"* (1.8) 

Female 

7-Month Interim Evaluation 

Lymph Node, Bronchial 6 7 7 6 

Hyperplasia, Lymphoid 0 0 4* (1.0) 3 (1.0) 

Pigmentation 0 0 7** (1.0) 6** (1.0) 

15-Month Interim Evaluation 

Lymph Node, Bronchial 5 5 5 5 

Hypetplasia, Lymphoid 0 0 3 (1.0) 3 (1.0) 

Pigmentation 0 4* (1.0) 5** (1.4) 5** (1.4) 

2-Year Study 

Lymph Node, Bronchial 49 50 53 52 

Hyperplasia, Lymphoid 1 (4.0) 5 (1.6) 20** (1.5) 13"* (1.7) 

Pigmentation 0 43** (1.5) 52** (1.8) 47** (1.8) 

* Significantly different (P_<0.05) from the control group by the Fisher exact test (interim evaluations) or the logistic regression test 

(2-year study) 

** P~0.01 

a Number of animals with lymph node examined microscopically 

b Number of animals with lesion 

c Average severity grade of lesions in affected animals: 1 = minimal, 2 = mild, 3 = moderate, 4 = marked 
Results 67 

Adrenal Medulla: At 2 years, there was an exposure-related increase in the incidence of benign 

pheochromocytoma in males and, more significantly, 

in females (Tables 16, A3, and B3). The incidence 

of bilateral benign pheochromocytoma in 2.5 mg/m 3 

females was significantly greater than that of the 

controls. The incidence of all benign pheochromocytoma in 2.5 mg/m 3 females was significantly 

greater than that in the controls and exceeded the 

historical control range (Tables 16 and B4b). There 

was also an exposure-related increase in the incidence of benign or malignant pheochromocytoma 

(combined) in males. The incidence of benign or 

malignant pheochromocytoma (combined) in 

2.5 mg/m ~ males was significantly greater than that 

of the controls, and the incidences in 1.25 and 

2.5 mg/m 3 males exceeded the historical control 

range (Tables 16 and A4b). Benign pheochromocytomas are discrete clusters, sheets, or broad 

trabeculae of medullary cells (Plate 4). They range 

in size from those that merely compress adjacent 

tissue to those that expand to replace not only the 

adrenal medulla, but also the adrenal cortex, even to 

causing gross enlargement of the organ. Malignant 

pheochromocytomas invaded through the connective 

tissue capsule of the adrenal gland into surrounding 

tissue. The incidence of hyperplasia in 2.5 mg/m 3 

females was significantly greater than that of the 

controls. Hyperplasias are irregular packets or 

clusters of medullary cells mildly altered in size, 

shape, and/or staining but which do not distort the 

adjacent parenchyma. Microscopically, focal medullary hyperplasia and pheochromocytoma form a 

morphologic continuum. Focal preneoplastic hyperplasia and pheochromocytoma were mutually exclusive diagnoses in the adrenal medulla. One or the 

other of these diagnoses occurred in most adrenal 

glands of exposed male rats. 

Other Organs: There was an exposure-related 

decrease in the incidence of pituitary gland adenoma 

in males (24/53, 18/52, 16/52, 12/52; Table A3). 

There was an exposure-related increase in the incidence of interstitial cell adenoma in the testes of 

males (40/54, 46/53, 43/53, 47/52; Table A3). Very 

high incidences of pituitary gland neoplasms and 

testicular interstitial cell neoplasms occur spontaneously in F344/N rats in 2-year studies. 
68 Nickel Oxide, NTP TR 451 

TABLE 16 

Incidences of Neoplasms and Nonneoplastic Lesions of the Adrenal Medulla in Rats 

in the 2-Year Inhalation Study of Nickel Oxide 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 

Male 

15-Month Interim Evaluation 

Adrenal Medulla a 5 5 5 

Hyperplasia b 0 0 1 (2.0) c 

Pheochromocytoma Benign 0 0 2 

2-Year Study 

Adrenal Medulla 54 52 53 

Hyperplasia 25 (2.2) 27 (2.1) 26 (2.6) 

Pheochromocytoma Benign, Bilateral 10 11 9 

Pheochromocytoma Benign (Includes Bilateral) 

Overall rate d 27/54 (50%) 24/52 (46%) 26/53 (49%) 

Adjusted rate e 81.8 % 69.3 % 83.1% 

Terminal rate f 9/14 (64%) 6/15 (40%) 10/15 (67%) 

First incidence (day s) 475 570 519 

Logistic regression test g P=0.041 P=0.348N P=0.561N 

Pheochromocytoma Malignant 

Overall rate 0/54 (0%) 0/52 (0%) 1/53 (2%) 

Adjusted rate 0.0% 0.0% 2.8 % 

Terminal rate 0/14 (0%) 0/15 (0%) 0/15 (0%) 

First incidence _h _ 619 

Logistic regression test P < 0.001 -- P = 0.499 

• 

Pheochromocytoma Benign or Malignant l 

Overall rate 27/54 (50%) 24/52 (46%) 27/53 (51%) 

Adjusted rate 81.8 % 69.3 % 83.6 % 

Terminal rate 9/14 (64%) 6/15 (40%) 10/15 (67%) 

First incidence 475 570 519 

Logistic regression test P=0.O08 P=0.348N P=0.521 

(continued) 

5 

2 (3.0) 

0 

52 

24 (2.5) 

16 

32/52 (62%) 

93.8 % 

10/12 (83%) 

553 

P=0.095 

6/52 (12%) 

33.9% 

3/12 (25%) 

467 

P=0.015 

35/52 (67%) 

97.0% 

11/12 (92%) 

467 

P=0.027 
Results 69 

TABLE 16 

Incidences of Neoplasms and Nonneoplastic Lesions of the Adrenal Medulla in Rats 

in ..the 2-Year Inhalation Study of Nickel Oxide (continued) 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 

Female 

15-Month Interim Evaluation 

Adrenal Medulla 5 

Hyperplasia 1 (1.0) 

2-Year Study 

Adrenal Medulla 51 

Hyperplasia 8 (1.3) 

Pheochromocytoma Benign, Bilateral 1 

Pheochromocytoma Benign (Includes Bilateral) j 

• Overall rate 4/51 (8 %) 

Adjusted rate 15.1% 

Terminal rate 2/21 (10%) 

First incidence 558 

Logistic regression tes.t P < 0.001 

5 5 5 

0 1 (1.0) 0 

52 53 53 

12 (2.3) 14 (2.3) 22** (2.5) 

0 1 5 

7/52 (13%) 6/53 (11%) 18/53 (34%) 

21.1 % 22.0% 56.5% 

3/25 (12%) 2/20 (10%) 13/26 (50%) 

524 611 519 

P=0.288 P=0.385 P=0.001 

** Significantly different (P ~0.01) from the control group by" the logistic regression test 

a Number of animals with adrenal medulla examined microscopically 

b Number of animals with lesion 

c Average severity grade of lesions in affected animals: 1 = minimal, 2 = mild, 3 = moderate, 4 = marked 

d Number of animals with neoplasm per number of animals with adrenal medulla examined microscopically 

e Kaplan:Meier estimated neoplasm incidence at the end of the study after adjustment for intercurrent mortality 

f Observed incidence in animals surviving until the end of the study 

g In the control column are the P values associated with the trend test. In the exposure group columns are the P values corresponding to 

the pairwise comparisons between the controls and that exposure group. The logistic regression test regards lesions in animals dying 

prior to terminal kill as nonfatal. A lower incidence in an exposure group is indicated by N. 

h Not applicable; no neoplasms in animal group 

i Historical incidence for 2-year NTP inhalation studies with untreated control groups (mean ± standard deviation): 176/623 

(28.3% 5: 12.0%); range 8%-50%. Feed studies: 400/1,182 (33.8% 5: 10.9%); range 14%-63% 

J Historical incidence for 2-year NTP inhalation studies: 35/608 (5.8% 5: 4.9%); range 0%-14%. Feed studies: 49/1,175 

(4.2% 5: 2.5%); range 0%-8% 
70 Nickel Oxide, NTP TR 451 

Tissue Burden Analyses 

Nickel concentrations in the lung of exposed rats 

were significantly greater than those in the controls 

at 7 and 15 months, and nickel concentration 

increased with increasing exposure concentration and 

with time (Tables 17 and H4). At 7 and 15 months, 

the absolute lung weights of 1.25 and 2.5 mg/m 3 

males and females in the lung burden groups were 

significantly greater than those of the controls; also, 

the absolute lung weight of 0.62 mg/m 3 females was 

greater than that of the controls at 7 months. 

TABLE 17 

Lung Weight and Lung Burden in Rats in the 2-Year Inhalation Study of Nickel Oxide a 

0 mg/m a 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 

Male 

n 6 7 7 7 

7-Month Interim Evaluation 

Absolute lung wt (g) -. 1.72 ± 0.07 1.85 ± 0.07 2.43 ± 0.11"* 2.59 ± 0.06** 

#g Ni/lung _b 326 ± 29.6** 930 ± 21.3"* 1,817 ± 68.6** 

#g Ni/g lung -- 175 ± 10.6"* 388 ± 18.7"* 701 ± 24.1"* 

#g Ni/g control lung -- 189 ± 17.2"* 541 ± 12.4"* 1,057 ± 39.9** 

n 5 5 5 5 

15-Month Interim Evaluation 

Absolute lung wt (g) 2.20 ± 0.04 2.15 ± 0.10 3.30 ± 0.16"* 

#g Ni/lung -- 696 ± 41.6"* 2,439 ± 71.9"* 

pg Ni/g lung -- 328 ± 30.2** 746 ± 46.6** 

#g Ni/g control lung -- 317 ± 18.9"* 1,110 ± 32.7** 

4.09 ± 0.12"* 

4,573 ± 485.4** 

1,116 ± 108.2"* 

2,082 ± 221.1"* 

Female 

n 7 7 

7-Month Interim Evaluation 

Absolute lung wt (g) 1.14 ± 0.03 1.31 ± 0.03* 

#g Ni/lung -- 226 ± 13.3"* 

#g Ni/g lung -- 173 ± I0.1"* 

#g Ni/g control lung -- 198 ± 11.7"* 

n 5 5 

15-Month Interim Evaluation 

Absolute lung wt (g) 1.56 ± 0.11 1.79 ± 0.10 

pg Ni/iung -- 471 ± 42.5** 

#g Ni/g lung -- 262 5: 14.8"* 

#g Ni/g control lung -- 302 ± 27.3** 

7 6 

1.65 ± 0.07** 1.78 ± 0.08** 

792 ± 86.5** 1,279 ± 132.2"* 

477 ±44.4** 713 ± 45.2** 

694 ± 75.8** 1,122 ± 115.9"* 

5 5 

2.41 ± 0.11"* 3.02 ± 0.13"* 

1,703 ± 140.5"* 2,810 ± 389.1"* 

706 ± 41.8"* 949± 146.4"* 

1,093 ± 90.2** 1,804± 249.7** 

* Significantly different (P_<0.05) from the control group by Williams' test (lung weight) or Shirley's test (lung burden parameters) 

** P_<0.01 

a Mean ± standard error 

b Results were below 0.540 #g Ni (the limit Of detection) for 7-month males, 0.660 #g Ni for 7-month females, or 0.450 #g Ni for 

15-month males and females, or below the level of quantitation. 
Results 71 

MICE 

16-DAY STUDY 

One male mouse exposed to 5 mg/m 3 died on the last 

day of the study (Table 18); this death was not 

considered to be chemical related. Except for a 

slight body weight loss in 30 mg/m 3 males, final 

mean body weights and mean body weight gains of 

exposed male and female mice were similar to those 

of controls. No clinical findings in any group were 

related to nickel oxide exposure. 

TABLE 18 

Survival and Body Weights of Mice in the 16-Day inhalation Study of Nickel Oxide 

Mean Body Weight b (g) Final Weight 

Dose Survival a Initial Final Change Relative to Controls 

(mg/m 3) (%) 

Male 

0 5/5 22.6 5:0.2 23.9 5:0.8 1.3 5:0.6 

1.2 5/5 23.6 5:0.2 23.9 5:0.5 0.3 5:0.5 I00 

2.5 5/5 22.6 5:0.4 23.8 ± 0.7 1.2 5:0.7 100 

5 4/5 c 22.6 5:0.5 23.3 5:0.5 1.1 5:0.4 98 

10 5/5 22.6 5:1.2 24.4 5:0.8 1.8 5:0.4 102 

30 5/5 22.4 5:0.5 22.3 ± 0.4 -0.1 5:0.5 94 

Female 

0 5/5 18.2 5:0.4 20.2 5:0.5 2.0 5:0.6 

1.2 5/5 18.2 ± 0.2 20.2 5:0.2 2.0 5:0.3 100 

2.5 5/5 18.4 ± 0.5 19.4 ± 0.6 1.0 5:0.7 96 

5 5/5 17.6 5:0.5 20.2 5:0.3 2.6 ± 0.3 100 

10 5/5 17.2 5:0.4 19.2 5:0.3 2.0 5:0.2 95 

30 5/5 18.4 5:0.2 19.3 5:0.3 0.9 5:0.1 95 

a Number of animals surviving at 16 days/number initially in group 

b Weights and weight changes are given as mean 5: standard error. Subsequent calculations are based on animals surviving to the end of 

the study. Differences from the control group were not significant by Dunnett's test. 

c Day of death: 16 
72 Nickel Oxide, NTP TR 451 

There were no chemical-related organ weight 

changes (Table F5). At necropsy, chemical-related 

gross lesions were limited to a slight enlargement of 

the bronchial lymph nodes in two males and two 

females exposed to 30 mg/m3; in one male exposed 

to 30 mg/m 3, there was a solitary gray focus on the 

right intermediate lung lobe. Microscopically, the 

lymph node enlargement was attributed to lymphoid 

hyperplasia. .Histopathologic changes were also 

present in the lungs (Table 19). In most mice 

exposed to 30 mg/m 3, there were inflammatory cell 

infiltrates in the pulmonary interstitium, primarily 

around blood vessels, and an increase in the number 

of alveolar macrophages in the lung. These inflammatory lesions were most prominent in the gray 

focus observed grossly in one male mouse. Pigment, 

consisting of densely stained, black particles, was 

present in the cytoplasm of alveolar macrophages as 

well as extracellularly within the alveolar spaces. At 

the lower exposure concentrations, histopathologic 

changes in the lungs were limited to accumulation of 

alveolar macrophages and the presence of pigment 

particles. No chemical-related histopathologic 

changes were observed in the lungs of mice exposed 

to 1.2 mg/m 3. 

Concentrations of nickel in the lung increased with 

exposure concentration and were significantly greater 

than those of the controls in 1.2, 2.5, and 5 mg/m 3 

males and females (Tables 20 and I1). 

Because of the severity of lung lesions in mice 

exposed to 30 mg/m 3, 10 mg/m 3 was selected as the 

highest exposure concentration for the 13-week 

study. 

TABLE 19 

Incidences of Sdected Nonneoplastic Lesions in Mice in the 16-Day Inhalation Study of Nickel Oxide 

0 mg/m 3 1.2 mg/m 3 2.5 mg/m 3 5 mg/m 3 10 mg/m 3 30 mg/m 3 

Male 

Lung a 5 5 

Alveolar Macrophage Hyperplasia b 0 0 

Interstitial Infiltrate 0 0 

Pigment 0 0 

d Lymph Node, Bronchial 3 -- 

Hyperplasia 0 

5 5 5 5 

0 0 5** (1.0) c 5** (2.6) 

0 0 0 5** (2.8) 

4* (1.0) 5** (1.0) 5** (2.0) 5** (3.0) 

3 4 

0 2 (2.5) 

Female 

Lung 5 5 5 5 5 5 

Alveolar Macrophage Hyperplasia 0 0 0 0 3 (1.0) 5** (2.0) 

Interstitial Infiltrate 1 (1.0) 0 0 1 (1.0) 0 4 (1.3) 

Pigment 0 0 3 (1.0) 5** (1.0) 5** (1.8) 5** (2.2) 

Lymph Node, Bronchial 2 -- -- -- 3 4 

Hyperplasia 0 0 2 (2.0) 

* Significantly different (P_<0.05) from the control group by the Fisher exact test 

** P<_0.01 

a Number of animals with organ examined microscopically 

b Number of animals with lesion 

c Average severity of lesions in affected animals: 1 = minimal; 2 = mild; 3 = moderate; 4 = marked 

d Tissue not examined at this exposure concentration 
Results 73 

TABLE 20 

Lung Weight and Lung Burden in Mice in the 16-Day Inhalation Study of Nickel Oxide a 

0 mg/m 3 1.2 mg/m 3 2.5 mg/m 3 5 mg/m 3 

n 5 5 5 5 

Male 

Absolute lung wt (g) 0.159 ± 0.005 0.154 ± 0.009 0.156 ± 0.003 0.156 ± 0.010 

#g Ni/lung _b 5 ± 0.1"* 7 ± 0.5** 13 ± 0.7** 

#g Ni/g lung -- 32 ± 2.4** 46 ± 3.6** 84 ± 7.8** 

~g Ni/g control lung -- 31 ± 0.8** 45 ± 3.1"* 81 ± 4.5** 

Female 

Absolute lung wt (g) 0.149 ± 0.006 0.133 ± 0.004 0.141 ± 0.006 0.168 ::t: 0.006 

~g Ni/lung -- 4 ± 0.2** 6 ± 0.4** 12 ± 0.8** 

~g Ni/g lung -- 31 ± 2.1"* 43 ± 0.9** 71 ± 5.7** 

#g Ni/g control lung -- 27 ± 1.3"* 41 ± 2.5** 80 ± 5.7** 

** Significantly different (P <_0.01) from the control group by Dunnett's test (lung weight) or Shirley's test (lung burden parameters) 

a Mean :1: standard error 

b Results were below 0.213 ~g Ni (the limit of detection), or below the level of quantitation. 
74 Nickel Oxide, NTP TR 451 

13-WEEK STUDY 

One control female, three 1.2 mg/m 3 females, one 

10 mg/m 3 male, and one l0 mg/m 3 female died 

during the study (Table 21). None of these deaths 

wcrc considered to bc related to nickel oxide exposure. Final mean body weights and mean body 

weight gains of exposed male and female mice were 

similar to those of the controls, and no clinical 

findings in any group were related to nickel oxide 

exposure. 

In general, hematology differences in the mice 

(Table G3) were similar to those reported for rats at 

13 weeks. The mice were less affected than the rats, 

and minimal differences occurred in fewer end points 

and exposure groups. Minimal lymphocytosis 

occurred, indicated by a lymphocyte count in 

10 mg/m 3 males that was greater than that of the 

controls. Hematocrit values and erythrocyte counts 

in 5 and 10 mg/m 3 females and hemoglobin concentration in 5 mg/m 3 females were minimally 

greater than those of the controls. 

No significant differences in sperm morphology or 

vaginal cytology between control and exposed mice 

were observed (Table J2). 

TABLE 21 

Survival and Body Weights of Mice in the 13-Week Inhalation Study of Nickel Oxide 

Mean Body Weight b (g) Final Weight 

Dose Survival a Initial Final Change Relative to Controls 

(mg/m ~) (%) 

Male 

0 10/10 23.0 ::t: 0.9 32.4 ± 0.4 9.4 ± 0.7 

0.6 10/10 23.7 ± 0.3 32.6 5:0.6 8.9 ± 0.5 101 

1.2 10/10 23.5 ± 0.4 32.0 :t: 0.3 8.5 ± 0.4 99 

2.5 I0/10 23.7 ± 0.5 31.4 ± 0.5 7.7 ± 0.6 97 

5 10/10 22.5 ± 0.7 31.7 =1:0.9 9.2:5:0.8 98 

10 9/10 c 23.4 5:0.4 31.3 :t: 0.6 7.7:5:0.7 97 

Female 

0 9/10 d 19.8 ± 0.4 28.8 ± 0.5 9.0 ± 0.8 

0.6 10/10 19.9 ± 0.6 27.9 5:0.6 8.0 ± 0.8 97 

1.2 7/10 e 19.5 ± 0.4 28.7 ± 1.0 9.4 ::t:: 1.2 100 

2.5 10/10 20.3 ± 0.5 27.6 :t: 0.8 7.3 ± 0.5 96 

5 10/10 19.6:5:0.6 27.0 ± 0.7 7.4 ± 0.6 94 

10 9/10 f 20.3 ± 0.5 28.1 5:0.5 7.9 ::t: 0.2 97 

a Number of animals surviving at 13 weeks/number initially in group 

b Weights and weight changes are given as mean ± standard error. Subsequent calculations are based on animals surviving to the end of 

the study. Differences from the control group were not significant by Dunnett's test. 

e Week of death: 4 

d Week of death: 6 

e Week of death: 2, 2,2 

f Week of death: 8 
Results 75 

Absolute and relative lung weights of 10 mg/m 3 

males and females and the relative lung weight of 

5 mg/m 3 females were significantly greater than 

those of the controls (Table F6). Absolute and 

relative liver weights of 10 mg/m ~ males and relative 

liver weight of 5 mg/m 3 males were significantly less 

than those of the controls. At necropsy, chemicalrelated gross lesions were limited to a mild enlargemerit of the bronchial lymph nodes in four males and 

six females exposed to 10 mg/m 3. Three males and 

three females exposed to 5 mg/m 3 had similar gross 

lesions; enlarged lymph nodes were also observed in 

four 2.5 mg/m 3 females. Chemical-related histopathologic lesions were present in the lungs and 

bronchial lymph nodes (Table 22). Microscopically, 

the lymph node enlargement was usually attributed to 

lymphoid hyperplasia characterized by an increase in 

the number of lymphocytes, primarily in the paracortical areas of the lymph nodes. Lymphoid hyperplasia was present in mice exposed to 2.5, 5, or 

10 mg/m 3. Densely stained, black pigment particles 

and aggregates of these pigment particles were 

present in the lymph nodes of 2.5, 5, and 10 mg/m 3 

males and females. There were exposure- and 

chemical-related inflammatory lesions and pigment in 

the lungs of mice. At 0.6, 1.2, and 2.5 mg/m 3, 

there was a minimally detectable increase in the 

number of macrophages within the alveolar spaces. 

Pigment particles were present in the cytoplasm of 

alveolar macrophages as well as extracellularly 

within the alveolar spaces. At 5 and 10 mg/m 3, the 

severity and spectrum of inflammatory changes in 

the lung were slightly increased. Inflammatory 

lesions included interstitial infiltrates of primarily 

lymphocytes around blood vessels and chronic active 

inflammation characterized by a mild thickening of 

alveolar septa with a mixture of neutrophils and 

mononuclear inflammatory ceils and a few fibroblasts. Granulomatous inflammation also occurred 

in a few mice exposed to 10 mg/m 3 and consisted of 

scattered, focal aggregates of large, epithelioid 

macrophages. 

At the end of the 13-week study, nickel concentrations in the lung of 0.6, 2.5, and 10 mg/m 3 males 

were significantly greater than that in the controls, 

and absolute lung weight of these I0 mg/m 3 males 

was significantly greater than that of the controls 

(Tables 23 and 12). 
76 Nickel Oxide, NTP TR 451 

TABLE 22 

Incidences of Selected Nonneoplastic Lesions in Mice in the 13-Week Inhalation Study of Nickel Oxide 

0 mg/m 3 0.6 mg/m 3 1.2 mg/m 3 2.5 mg/m 3 5 mg/m 3 10 mg/m 3 

Male 

Lung a 10 10 10 10 10 9 

Alveolar Macrophage Hyperplasia b 0 10"* (1.0) c 10"* (1.0) 10"* (1.0) 10"* (1.0) 9** (1.1) 

Inflammation, Chronic Active 0 0 0 0 0 3 (1.0) 

Inflammation, Granulomatous 0 0 0 0 0 3 (1.0) 

Perivascular Lymphocytic Infiltrate 0 0 0 1 (1.0) 3 (1.0) 8** (1.0) 

Pigment 0 10"* (1.0) 10"* (1.0) 10"* (1.0) 10"* (1.0) 9** (1.0) 

Lymph Node, Bronchial 7 10 6 8 6 7 

Hyperplasia 0 0 0 1 (1.0) 3 (1.0) 5** (1.3) 

Pigment 0 0 0 5* (1.0) 5** (1.0) 6** (1.0) 

Female 

Lung 9 10 7 10 10 9 

Alveolar Macrophage Hyperplasia 0 10"* (1.0) 7** (1.0) 10"* (1.0) 10"* (1.1) 9** (1.0) 

Inflammation, Chronic Active 0 0 0 0 1 (1.0) 3 (1.1) 

Inflammation, Granulomatous 0 0 0 0 0 1 (1.0) 

Perivascular Lymphocytic Infiltrate 0 1 (1.0) 0 4 (1.0) 6** (1.1) 8** (1.1) 

• 

Pigment 0 10"* (1.0) 7** (1.0) 10"* (1.0) 10"* (1.0) 9** (1.0) 

Lymph Node, Bronchial 8 9 4 10 10 9 

Hyperplasia 0 0 0 4 (1.0) 3 (1.0) 7** (1.3) 

Pigment 0 0 0 8** (1.0) 8** (1.0) 8** (1.0) 

* Significantly different (P_<0.05). from the control group by the Fisher exact test 

** P_<0.01 

a Number of animals with organ examined microscopically 

b Number of animals with lesion 

c Average severity of lesions in affected animals: 1 = minimal; 2 = mild; 3 = moderate; 4 = marked 
Results 77 

TABLE 23 

Lung Weight and Lung Burden in Male Mice in the 13-Week Inhalation Study of Nickel oxide a 

0 mg/m 3 0.6 mg/m 3 2.5 mg/m 3 10 mg/m 3 

Male 

n 6 5 6 5 

Absolute lung weight (g) 0.176 ± 0.012 0.179 ± 0.004 0.179 5:0.014 0.244 5: 0.019"* 

#g Ni/lung _b 7 ± 0.6** 36 5: 3.3** 171 5: 15.5"* 

#g Ni/g lung -- 42 ± 2.9** 202 ± 18.3"* 736 5: 123.0"* 

/zg Ni/g control lung -- 42 5: 3.4** 204 ± 18.9"* 973 ± 88.0** 

** Significantly different (P _<0.01) from the control group by Dunnett's test (lung weight) or Shirley's test (lung burden parameters) 

a Mean ± standard error 

b Results were below 0.255/~g Ni (the limit of detection), or below the level of quantitation. 

Dose Selection Rationale: Based on the wider 

spectrum of inflammatory lesions in the lung and 

increased lung weights in 10 mg/m 3 male and female 

mice in the 13-week study, nickel oxide exposure 

concentrations selected for the 2-year inhalation 

study in mice were 1.25, 2.5, and 5 mg/m 3. 
78 Nickel Oxide, NTP TR 451 

2-Y .AR STUDY 

Survival 

Estimates of 2-year survival probabilities for male 

and female mice are shown in Table 24 and in the 

Kaplan-Meier survival curves in Figure 4. Survival 

of exposed male and female mice was similar to that 

of the controls. 

Body Weights and Clinical Findings . 

Mean body weights of exposed males and of females 

exposed to 1.25 or 2.5 mg/m 3 were similar to those 

of the controls throughout most of the study 

(Tables 25 and 26 and Figure 5). Mean body 

weights of females exposed to 5 mg/m 3 were less 

than those of the controls during the second year of 

the study. No chemical-related clinical findings were 

observed in male or female mice during the 2-year 

study. 

Hematology 

.No chemical-related differences in hematology 

parameters were observed in male or female mice at 

the 15-month interim evaluation (Table G4). 

TABLE 24 

Survival of Mice in the 2-Year Inhalation Study of Nickd Oxide 

0 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 5 mg/m 3 

Animals initially in study 78 77 76 79 

7-Month interim evaluation a 5 5 5 5 

15-Month interim evaluation a 5 5 5 5 

Accidental deaths a 10 0 0 0 

Missexed a 1 0 0 0 

Moribund 23 26 26 29 

Natural deaths 15 18 11 17 

Animals surviving to study termination 19 23 29 23 

Percent probability of survival at end of study b 33 34 44 33 

Mean survival (days) ¢ 526 605 649 612 

Survival analysis d P=0.830N P=0.942N P=0.188N P=0.93 IN 

Female 

Animals initially in study 74 76 74 75 

7-Month interim evaluation a 5 5 5 5 

15-Month interim evaluation a 5 5 5 5 

Accidental deaths a 1 0 1 0 

Pregnant/Missexed a 0 0 1 1 

Moribund 15 18 9 16 

Natural deaths 7 8 11 10 

Animals surviving to study termination 41 e 40 f 42 38 

Percent probability of survival at end of study 65 61 68 59 

Mean survival (days) 621 665 640 662 

Survival analysis P=0.763 P=0.854 P=0.877N P=0.735 

a Censored from survival analyses 

b Kaplan-Meier determinations based on the number of animals alive on the first day of terminal sacrifice 

c Mean of all deaths (uncensored, censored, and terminal sacrifice) 

o The result of the life table trend test (Tarone, 1975) is in the control column, and the results of the life table pairwise comparisons (Cox, 

1972) with the controls are in the exposed columns. A negative trend or a lower mortality in an exposure group is indicated by N. 

e Includes one animal that died during the last week of the study. 

f Includes two animals that died during the last week of the study. 
Results 79 

1.01 : ' 

IL~o 

0.~- 

0.~. 

~.~. ....... 

• o~.~ i -~.: 

0 I.ZS MG/M$ " " ~I~' 0.4- ~ ~.~/.~ ~. ~ ...... 

0 ~ ~lu~ 

O,] / 

I~ 30 45 60 75 90' 105 120 

WEEKS ON STUDY 

1.01 

O.g- 

~ O.B- 

~ 0.7- 

O 

~ 0.~- I1~ 

.~ 

~ 0.~- 

0.4. 

; 

~ .................................. 

FEMALE MICE I : i 

• 0 ~/u~ 

O t,2~ UG/U~ 

l~ 2.~ ~a/us 

E] ~ M~IM$ 

: : 

I~ ~0 

0.3 / 

0 4,~ ~0 75 tO,~ 120 

WEEKS ON STUDY 

FIGURE 4 

Kaplan-Meier Survival Curves for Mice Administered Nickel Oxide by Inhalation 

for 2 Years 
80 Nickel Oxide, NTP TR 451 

TABLE 25 

Mean Body Weights and Survival of Male Mice in the 2-Year Inhalation Study of Nickd Oxide a 

Weeks 0 mg/m3 1.25 mg/m 3 2.5 mg/m 3 5 mg/m 3 

on Av. Wt. No. of Av. Wt. Wt. (% of No. of Av. Wt. Wt. (% of No. of Av. Wt. Wt. (% of No. of 

Study (g) Survivors (g) controls) Survivors (g) controls) Survivors (g) controls) Survivors 

1 23.8 79 23.6 99 80 23.4 98 80 23.4 98 80 

2 25.9 78 26.0 100 80 26.0 100 80 25.7 99 80 

3 27.4 78 27.6 101 80 27.4 100 80 27.4 100 80 

4 27.7 78 28.0 101 79 27.8 100 80 28.2 102 79 

5 28.1 78 28.2 100 79 28.3 101 80 28.7 102 79 

6 29.9 78 29.6 99 79 29.7 99 80 30.1 101 79 

7 30.7 78 30.2 98 79 30.0 98 80 30.6 100 79 

8 30.5 78 30.4 100 79 30.4 100 80 30.7 101 79 

10 31.2 78 31.0 99 79 30.9 99 80 31.3 100 79 

11 31.9 68 30.9 97 79 31.4 98 80 31.9 100 79 

12 31.6 68 31.1 98 79 31.3 99 80 31.9 101 79 

13 32.2 68 31.9 99 79 31.6 98 80 32.7 102 79 

17 33.5 68 33.3 99 78 33.4 100 80 34.0 102 79 

21 34.8 68 34.6 99 77 34.5 99 80 35.3 101 78 

25 36.1 65 35.5 98 76 35.6 99 79 35.9 99 78 

29 b 36.5 60 35.7 98 71 35.9 98 74 36.9 101 72 

33 37.4 60 37.0 99 70 37.3 100 74 38.0 102 71 

37 38.7 60 37.7 97 70 38.0 98 73 38.3 99 70 

41 39.2 60 38.2 97 70 38.4 98 73 39.1 100 69 

45 39.0 59 38.4 99 68 38.6 99 73 39.5 101 69 

49 40.0 58 39.1 98 67 39.2 98 73 40.0 100 68 

53 40.9 58 39.8 97 67 40.5 99 71 40.9 100 68 

57 41.4 57 40.5 98 67 40.7 98 71 40.9 99 68 

61 41.4 57 41.0 99 67 41.8 101 71 41.8 101 67 

65 42.2 56 41.0 97 65 41.9 99 71 41.7 99 65 

69 b 42.6 50 41.6 98 58 41.4 97 62 41.9 98 59 

73 42.4 49 40.5 96 55 41.4 98 61 41.6 98 56 

77 42.0 47 40.2 96 54 40.9 97 60 41.0 98 55 

81 42.2 44 39.5 94 51 40.9 97 55 40.6 96 52 

85 41.7 41 39.5 95 49 40.8 98 54 40.4 97 48 

89 42.3 36 39.2 93 44 40.2 95 52 40.1 95 43 

93 41.6 31 38.5 93 39 39.4 95 49 38.7 93 41 

97 41.4 27 38.0 92 35 38.8 94 42 38.9 94 36 

101 41.2 24 38.2 93 31 38.2 93 37 38.2 93 30 

Mean for weeks 

1-13 29.2 29.0 99 29.0 99 29.4 I01 

14-52 37.2 36.6 98 36.8 99 37.4 101 

53-101 41.8 39.8 95 40.5 97 40.5 97 

a A few animals in each exposure group were used only in special studies. 

b Interim evaluations occurred during weeks 29 and 66. 
Results 81 

TABLE 26 

Mean Body Weights and Survival of Female Mice in the 2-Year Inhalation Study of Nickel Oxide a 

Weeks 0 mg/m3 1.25 mg/m 3 2;5. mg/m ~ 5 mg/m 3 

on Av. Wt. No. of Av. Wt. Wt. (% of No. of Av. Wt. Wt. (% of No. of Av. wt. wt. (% of No. of 

Study (g) Survivors (g) controls) Survivors (g) controls) Survivors (g) controls) Survivors 

1 19.3 80 19.5 101 80 19.0 98 80 18.9 98 80 

2 21.2 79 21.8 103 80 21.0 99 80 21.1 100 80 

3 22.3 78 23.1 104 80 22.7 102 78 22.8 102 80 

4 22.3 77 23.7 106 80 23.3 105 78 23.6 106 80 

5 23.3 76 24.0 103 80 23.6 101 78 23.8 102 80 

6 25.3 76 25.6 101 80 25.2 100 77 25.4 100 80 

7 26.1 76 26.1 100 79 25.7 99 77 26.1 100 80 

8 26.2 76 26.5 101 79 25.9 99 77 25.5 97 80 

10 26.7 76 27.1 102 79 26.1 98 75 26.6 100 80 

11 27.4 76 26.9 98 79 26.8 98 75 27.4 100 79 

12 27.3 76 26.9 99 79 26.8 98 75 27.2 100 79 

13 27.8 76 27.8 100 79 27.3 98 75 27.9 100 79 

17 29.4 74 29.9 102 79 28.9 98 75 29.3 100 79 

21 30.3 73 31.1 103 79 30.4 100 75 30.9 102 78 

25 31.6 73 32.0 101 78 31.7 100 75 31.6 100 78 

29 b 33.0 68 33.0 100 73 31.9 97 70 32.3 98 73 

33 34.6 67 34.1 99 72 33.8 98 70 33.7 97 73 

37 35.7 67 35.2 99 72 34.2 96 70 34.6 97 73 

41 36.5 67 35.7 98 72 34.8 95 70 35.6 98 73 

45 36.7 67 36.2 .99 72 35.6 97 70 36.4 100 72 

49 37.7 67 37.5 I00 71 36.5 97 67 36.6 97 72 

53 39.0 66 38.6 99 71 38.0 97 67 37.5 96 72 

57 39.4 66 39.1 99 71 37.9 96 67 37.0 94 72 

61 39.7 66 39.7 100 71 38.6 97 ~7 38.0 96 71 

65 40.6 66 39.8 98 71 39.5 97 66 38.0 94 71 

69 b 41.4 61 40.8 99 65 39.0 94 61 39.4 95 65 

73 40.7 61 39.6 97 65 38.9 96 61 38.9 96 62 

77 40.5 60 39.3 97 64 38.8 96 60 38.5 95 61 

81 40.3 58 38.1 95 63 38.3 95 60 37.5 93 61 

85 39.3 57 37.8 96 61 38.1 97 56 36.8 94 60 

89 39.3 54 37.7 96 58 38.1 97 56 35.3 90 56 

93 39.2 52 37.2 95 55 37.2 95 54 34.6 88 53 

97 38.2 52 36.4 95 52 36.6 96 49 35.5 93 49 

101 38.3 49 36.7 96 47 36.0 94 48 34.5 90 46 

Mean for weeks 

1-13 24.6 24.9 101 24.5 100 24.7 100 

14-52 33.9 33.9 100 33.1 98 33.4 99 

53-101 39.7 38.5 97 38.1 96 37.0 93 

a A few animals in each exposure group were used only in special studies. 

b Interim evaluations occurred during weeks 29 and 66. 
82 Nickel Oxide, NTP TR 451 

Z 

t~l 

0 

ID 

Z 

W 

4@ 

35  ̧ 

30- 

25, 

20- 

I$ 

0 

i . ~ @ ~ ~!! | | |" | | 

........................................ i ....................... n ~ .......... o~@ ~ ~ .................. 

: ~,,~ ~ ......... ~..o.oo0~0 

.... ......... ................... ! .............. ', ............... i .............. 

~ : , 

@ ~ 

....... : ............ 

I'~ 30 4~5 ~uo 715 9uo tO~l 

WEEKS ON STUDY 

: ~ [ ,,aLE ~,~[ I 

: m. ~/-~ I 

..... : ...... :~ ..... o ~.~*~/~ | 

~ ~.~.oI.~ l 

0 s .oI.~ I 

. 

i 

Z 

0 

m 

Z 

L~J 

45- 

3@. 

30 

2S20- 

15 

0 

! ~ =~i== 

.................. ~ ................. i ............................ ,er~~~i~ .... ~~"~ .............. 

i ! ! @ ~ ~ (~ o i~ 1~1 ~ ~ _ m m 

:. :: iHO °i i o ::n~ 

................. ~ ~ ..................... ~,~ ~ ~ ' ~ .................. ~ ................... ~ .................. 0.,,o.o. ~ " ~. .. 

::~ ~ ......................... ~. ~ 2 .... .............................................................. 

................... t~ ~ ~ 

..... ~. ........................................... ~ .................................................................................. 

~ I m o.~/.~ 

..................................................... : ................ ~ .............. ~ ~ ~.~.~/.~ 

I ~ ~'~ ~/.s 

~ ~ ~ ~.~/.~ 

~ ~ 

. 

,~ ~o A ~o ,~ ~o 

WEEKS ON STUDY 

tO'; 

FIGURE 5 

Growth Curves for Mice Administered Nickel Oxide by Inhalation for 2 Years 
Results 83 

Pathology and Statistical Analyses 

This section describes the statistically significant or 

biologically noteworthy changes in the incidences of 

nonneoplastic lesions of the lung, lymph nodes, and 

urogenital tract and neoplasms of the lung, liver, and 

harderian gland. Summaries of the incidences of 

neoplasms and nonneoplastic lesions, individual 

animal tumor diagnoses, statistical analyses of 

primary neoplasms that occurred with an incidence 

of at least 5 % in at least one animal group, and 

historical incidences for the neoplasms mentioned in 

this section are presented in Appendix C for male 

mice and Appendix D for female mice. 

Lung: At the 7-month interim evaluation, absolute 

and relative lung weights of males exposed to 2.5 or 

5 mg/m 3 were significantly greater than those of the 

controls (Table F7). At 15 months, absolute and 

relative l!ang weights of 5 mg/m 3 males and females 

were significantly greater than those of the controls 

(Table F8). At 2 years, the incidence of alveolar/ 

bronchiolar adenoma in 2.5 mg/m 3 females was 

significantly greater than that of the controls, as was 

the incidence of alveolar/bronchiolar adenoma or 

carcinoma (combined) in 1.25mg/m 3 females 

(Tables 27 and D3). The incidences of these neoplasms in these groups exceeded the historical 

control ranges from NTP inhalation studies 

(Tables 27 and D4). Alveolar/bronchiolar adenomas 

were typically discrete proliferations of alveolar and 

papillary structures lined by a single layer of large 

cuboidal epithelial cells that compressed the adjacent 

lung parenchyma. Alveolar/bronchiolar carcinomas 

were either discrete or invasive and consisted of 

alveolar, papillary, or tubular structures composed of 

densely packed atypical epithelial cells usually 

forming multiple layers or solid clusters. Morphologically, alveolar/bronchiolar neoplasms were 

typical of spontaneously occurring neoplasms in 

B6C3F1 mice. 

Generally, incidences of chronic inflammation 

increased with increasing exposure concentration in 

males and females at 7 and 15 months (Tables 27, 

C5, and D5). Bronchialization of minimal severity 

in exposed animals and proteinosis were first 

observed at 15 months. At 2 years, the incidences 

of chronic inflammation, bronchialization, and 

proteinosis in exposed groups of males and females 

were significantly greater than those of the controls. 

The severity of chronic inflammation .increased with 

increasing exposure concentration in females, and 

proteinosis was most severe in 5 mg/m 3 males and 

females. Chronic inflammation included small to 

moderate numbers of mononuclear inflammatory 

cells (principally lymphocytes, with fewer macrophages) around the vessels and airways; variable 

numbers of macrophages within alveolar spaces, 

often obscured by particulate pigment; and occasional focal aggregates of macrophages mixed with 

lymphocytes, or rarely neutrophils, within alveolar 

lumens. Occasionally, long, thin, brightly eosinophilic crystalline material within alveolar lumens or 

airways was observed either free or within macrophages (Plate 5). These crystalline structures also 

occurred in a few control mice and were associated 

with inflammation around pulmonary neoplasms. 

Bronchialization consisted of hyperplastic and/or 

hypertrophic cuboidal epithelial cells extending from 

terminal bronchioles into alveolar ducts and adjacent 

proximal alveoli of nickel oxide exposed mice 

(Plate 6). Because these cuboidal cells were not 

observed to have cilia and no attempts were made to 

determine their cell of origin, the term bronchialization in this study corresponds to the overall light 

microscopic appearance only. Proteinosis was an 

accumulation of varying amounts of eosinophilic 

granular to hyaline material, usually containing 

pigment particles, within alveolar lumens. 

Pigment occurred in the lungs of nearly all exposed 

mice at 7 and 15 months and at 2 years, and the 

severity increased with increasing exposure concentration (Tables 27, C5, and D5). Pigmentation of 

the lung consisted of fine, black, slightly refractile 

particles, either within alveolar macrophages or 

adherent to proteinaceous material in the alveolar 

spaces (Plate 7). Exposure-related pigment in the 

lung was distinguishable from the spontaneously 

occurring endogenous pigment hemosiderin, Occasionally, pigmented macrophages were observed in 

the interstitium or lymphoid tissue around airways. 

Focal alveolar hyperplasia in the lungs secondary to 

an inflammatory reaction was not separately diagnosed. Focal alveolar epithelial hyperplasia, part of 

the morphologic continuum toward neoplasia, was 

occasionally observed. Focal alveolar hyperplasia 

consisted of clusters of alveoii lined by a single layer 

of typical type II cuboidal epithelial cells maintaining 

normal alveolar architecture. 
84 Nickel Oxide, NTP TR 451 

TABLE 27 

Incidences of Neoplasms and Nonneoplastic Lesions of the Lung in Mice in the 2-Year Inhalation Study 

of Nickel Oxide 

0 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 5 mg/m 3 

Male 

7-Month Interim Evaluation 

Lung a 5 5 5 5 

Inflammation, Chronic b 0 2 (1.0) c 3 (1.0) 3 (1.0) 

Alveolus, Pigmentation 0 5** (1.0) 5** (1.0) 5** (1.2) 

Alveolar/bronchiolar Adenoma 1 0 0 0 

15-Month Interim Evaluation 

Lung 5 5 5 

Inflammation, Chronic 1 (1.0) 0 2 (1.0) 

Bronchialization 0 1 (1.0) 0 

Alveolar Epithelium, Hyperplasia, Focal 1 (3.0) 0 0 

Alveolus, Pigmentation 0 5** (1.2) 5** (1.4) 

Alveolus, Proteinosis 0 0 1 (1.0) 

Alveolar/bronchiolar Adenoma 1 0 0 0 

2-Year Study 

Lung 57 

Fibrosis 0 

Inflammation, Chronic 0 

Bronchialization 0 

Alveolar Epithelium, Hyperplasia, Focal 1 

Alveolus, Pigmentation 0 

Alveolus, Proteinosis 0 

Alveolar/bronchiolar Adenoma 

Alveolar/bronchiolar Carcinoma, 

Multiple 0 

Alveolar/bronchiolar Carcinoma 

(Single or Multiple) 4 

Alveolar/bronchiolar Adenoma or Carcinorna d 

Overall rate e 

Adjusted rate f 

Terminal rote g 

First incidefice (days) 

Logistic regression test h 

Female 

7-Month Interim Evaluation 

Lung 5 

Inflammation, Chronic 0 

Alveolus, Pigmentation 0 

(4.0) 

(continued) 

9/57 (16%) 

36.3% 

5/19 (26%) 

559 

P=0.393 

67 

0 

21"* (1.4) 

24** (1.0) 

1 (2.0) 

65** (1.1) 

12"* (1.2) 

10 

14/67 (21%) 

41.4% 

6/23 (26%) 

512 

P=0.322 

5 

1 (2.0) 

4* (1.0) 

66 

0 

34** (1.4) 

40** (1.0) 

2 (3.0) 

66** (1.7) 

22** (1.5) 

15/66 (23%) 

43.6% 

11/29 (38%) 

483 

P=0.380 

5 

4* (1.0) 

5** (1.2) 

5 

4 (1.8) 

2 (I.0) 

0 

5** (2.2) 

3 (1.0) 

69 

1 (I .0) 

55** (1.4) 

40** (1.0) 

0 

68** (2.1) 

43** (1.8) 

11 

14/69 (20%) 

39.7% 

6/23 (26%) 

489 

P=0.364 

5 

4* (1.3) 

5** (1.2) 
Results 85 

TABLE 27 

Incidences of Neoplasms and Nonneoplastic Lesions of the Lung in Mice in the 2-Year Inhalation Study 

of Nickel Oxide (continued) 

0 mg/m 3 1.25 mg/m 3 2.5 mg/m a 5 mg/m a 

Female (continued) 

15-Month Interim Evaluation 

Lung 5 5 5 5 

Inflammation, Chronic 0 2 (1.5) 4* (1.0) 4* (1.3) 

Bronchialization 0 0 3 (1.0) 3 (1.0) 

Alveolus, Pigmentation 0 4* (1.0) 5** (1.4) 5** (2.0) 

Alveolus, Proteinosis 0 0 0 3 (1.3) 

Alveolar/bronchiolar Adenoma 0 0 1 0 

2-Year Study 

Lung 64 66 63 64 

Fibrosis 0 0 1 (2.0) 3 (1.0) 

Inflammation, Chronic 7 (1.4) 43** (1.4) 53** (1.6) 52** (1.9) 

II!flammation, Chronic Active 0 0 1 (2.0) 0 

Bronchialization 0 35** (1.0) 39** (1.0) 40** (1.0) 

Alveolar Epithelium, Hyperplasia, Focal 0 0 1 (2.0) 0 

Alveolus, Pigmentation 0 64** (1.3) 61"* (1.9) 64** (2.4) 

Alveolus, Proteinosis 0 8** (1.5) 17"* (1.3) 29** (1.7) 

Alveolar/bronchiolar Adenoma, Multiple 0 2 0 0 

Alveolar/bronchiolar Adenoma 

(Single and Multiple) 2 4 10" 3 

Alveolar/bronchiolar Carcinoma, 

Multiple 0 1 0 0 

Alveolar/bronchiolar Carcinoma 

(Single and Multiple) 4 11 4 5 

Alveolar/bronchiolar Adenoma or Carcinoma i 

Overall rate 6/64 (9%) 15/66 (23%) 12/63 (19%) 8/64 (13%) 

Adjusted rate 13.8% 30.8% 25.7% 17.4% 

Terminal rate 4/41 (10%) 8/40 (20%) 8/42 (19%) 4/38 (11%) 

First incidence (days) 694 583 630 469 

Logistic regression test P=0.487N P=0.043 P=0.099 P=0.422 

* Significantly differem (P_<0.05) from the control group by the Fisher exact test (interim evaluations) or the logistic regression test 

(2-year study) 

** P_<0.01 

a Number of animals with lung examined microscopically 

b Number of animals with lesion 

c Average severity grade of lesions in affected animals: 1 =minimal, 2=mild, 3=moderate, 4=marked 

d Historical incidence for 2-year NTP inhalation studies with untreated control groups (mean ± sttandard deviation): 205/952 

(21.5% ± 8.0%); range 10%-42%. Feed studies: 249/1,319 (18.9% ± 7.6%); range 4%-32% 

e Number of animals with neoplasm per number of animals with lung examined microscopically 

f Kaplan-Meier estimated neoplasm incidence at the end of the study after adjustment for intercurrent mortality 

g Observed incidence in animals surviving until the end of the study 

h In the control column are the P values associated with the trend test. In the exposure group columns are the P values corresponding to 

the pairwise comparisons between the controls and that exposure group. The logistic regression test regards lesions in animals dying 

prior to terminal kill as nonfatal. A negative trend or a lower incidence in an exposure group is indicated by N. 

i Historical incidence for 2-year NTP inhalation studies: 97/944 (10.3% ± 3.7%); range 0%-16%. Feed studies: 102/1,319 

(7.7% ± 5.3%); range 2%-26% 
86 Nickel Oxide, NTP TR 451 

Bronchial Lymph Node: Lymphoid hyperplasia 

occurred in one 2.5 mg/m 3 male and one 1.25 mg/m 3 

female at 7 months (Tables 28, C5, and D5). At 

15 months, lymphoid hyperplasia occurred in males 

exposed to 2.5 and 5 mg/m 3 and in all exposed 

groups of females. At 2 years, lymphoid hypelrplasia 

occurred in some control animals, but this lesion was 

still observed more often in exposed males and 

females and the incidence increased with exposure 

concentration. Pigmentation was observed in the 

bronchial lymph nodes of exposed males and females 

at 7 and 15 months. Pigmentation was also observed 

in nearly all exposed animals at 2 years (Plate 8). 

Pigmentation was not observed in the bronchial 

lymph nodes of control males or females at any time. 

The severity of these lesions appeared to be unaffected by exposure concentration. 

Lymphoid hyperplasia was characterized by an 

increase in cortical or paracortical lymphocytes 

resulting in a mild to moderate increase in lymph 

node size. The lymphocytes were at different stages 

of differentiation, and the overall architecture of the 

lymph node was maintained. Pigmentation consisted 

of variable numbers of discrete aggregates of fine, 

black, granular material, apparently within macrophages, located predominantly within the medullary 

area. The pigment resembled that observed in the 

lung and was clearly related to nickel oxide exposure. 

Liver: At 2 years, the incidence of hepatocellular 

carcinoma in 1.25 mg/m 3 males was significantly 

greater than that of the controls (6/57, 16/67, 11/66, 

15/69; Table C3). However, the incidence was 

within the historical control range (Table C4b) and 

the incidence of adenoma or carcinoma (combined) 

was not significantly greater than that of the controls 

(12/57, 20/67, 23/66, 20/69). 
Results 87 

TABLE 28 

Incidences of Nonneoplastic Lesions of the Bronchial Lymph Node in Mice 

in the 2-Year Inhalation Study of Nickel Oxide 

0 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 5 mg/m 3 

Male 

7-Month Interim Evaluation 

Lymph Node, Bronchial a 4 3 5 4 

Hyperplasia, Lymphoid b 0 0 1 (1.0) c 0 

Pigmentation 0 2 (1.0) 5** (1.0) 4* (1.0) 

15-Month Interim Evaluation 

Lymph Node, Bronchial 5 5 5 5 

Hyperplasia, Lymphoid 0 0 2 (1.5) 4* (2.3) 

Pigmentation 0 4* (1.3) 5** (1.6) 5** (1.2) 

2-Year Study 

Lymph Node, Bronchial 45 56 61 62 

.Hyperplasia, Lymphoid 5 (2.0) 18" (1.8) 28** (2.0) 33** (1.8) 

Pigmentation 0 55** (1.5) 61"* (1.9) 60** (2.1) 

Female 

7-Month Interim Evaluation 

Lymph Node, Bronchial 3 4 5 5 

Pigmentation 0 1 (1.0) 5** (1.0) 5** (1.0) 

15-Month Interim Evaluation 

Lymph Node, Bronchial 5 5 5 5 

Hyperplasia, Lymphoid 0 3 (1.3) 4* (1.0) 4* (1.0) 

Pigmentation 0 4* (1.0) 5** (1.6) 5** (1.4) 

2-Year Study 

Lymph Node, Bronchial 54, 63 59 62 

Hyperplasia, Lymphoid 14 (1.8) 37** (2.0) 40** (1.9) 44** (2.2) 

Pigmentation 0 58** (1.5) 56** (1.8) 60** (2.0) 

* Significantly different (P_<0.05) from the control group by the Fisher exact test (interim evaluations) or the logistic regression test 

(2-year study) 

** P_<0.01 

a Number of animals with bronchial lymph node examined microscopically 

b Number of animals with lesion 

c Average severity grade of lesions in affected animals: 1 = minimal, 2 = mild, 3 = moderate, 4 = marked 
88 Nickel Oxide, NTP TR 451 

Tissue Burden Analyses 

Nickel concentrations in the lungs of exposed mice 

were significantly greater than those in the controls 

at 7 and 15 months, and nickel concentration increased with increasing exposure concentration and 

with time (Tables 29 and 13). In lung burden analysis groups, absolute lung weight of 2.5 and 5 mg/m 3 

males at 7 and 15 months and of 5 mg/m 3 females at 

15 months were significantly greater than those of 

the controls. 

TABLE 29 

Lung Weight and Lung Burden in Mice in the 2-Year Inhalation Study of Nickel Oxid~ a 

0 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 5 mg/m 3 

n 5 5 5 5 

Male 

7-Month Interim Evaluation 

Absolute lung weight (g) 0.192 5:0.009 0.208 5:0.004 0.240 5: 0.010"* 0.238 5: 0.006** 

pg Ni/lung _b 34 5: 2.1"* 107 5: 12.0"* 246 5: 11.2"* 

pg Ni/g lung -- 162 5: 9.6** 442 5: 37.1"* 1,034 5: 33.1"* 

#g Ni/g control lung -- 176 5: 11.0"* 556 5: 62.3** 1,283 5: 58.1"* 

15-Month Interim Evaluation 

Absolute lung weight (g) 0.234 5:0.017 0.246 5:0.021 0.306 5: 0.020* 0.382 ± 0.019"* 

t~g Ni/lung -- 80 5: 5.1"* 296 5: 35.5** 696 5: 81.9"* 

/zg Ni/g lung -- 331 5: 30.3** 959 5: 67.1"* 1,798 5: 134.5"* 

pg Ni/g control lung -- 340 ± 21.8"* 1,265 5: 151.5"* 2,973 5: 349.9** 

Female 

7-Month Interim Evaluation 

Absolute lung weight (g) 0.178 5:0.010 0.206 ± 0.011 0.228 5:0.019 0.232 5:0.022 

#g Ni/lung -- 35 5: 1.6"* 120 ± 8.1"* 196 ± 15.3"* 

pg Ni/g lung -- 169 ± 6.0** 533 5: 36.4** 861 5: 70.1"* 

#g Ni/g control lung -- 195 5: 9.1"* 674 5: 45.2** 1,101 5: 86.2** 

15-Month Interim Evaluation 

Absolute lung weight (g) 0.248 5:0.010 0.264 5:0.010 0.294 5:0.018 0.340 5: 0.026** 

/~g Ni/lung -- 119 5: 10.1"* 365 5: 39.9** 771 5: 111.9"* 

~tg Ni/g lung -- 451 5: 31.4"* 1,237 5: 102.6"* 2,258 5: 265.1"* 

pg Ni/g control lung -- 481 5: 40.9** 1,472 5: 160.9"* 3,108 ± 451.3"* 

* Significantly different (P<_0.05) from the comrol group by Williams' or Dunnett's test (lung weight) or Shirley's test (lung burden 

parameters) 

** P_<0.01 

a Mean 5: standard error 

b Results were below 0.400 pg Ni (the limit of detection) for 7-month mice or 0.352 pg Ni for 15-month mice, or below the level of 

quantitation. 

GENETIC TOXICOLOGY 

Nickel oxide was tested for induction of micronuclei 

in normochromatic erythrocytes of male and female 

mice exposed by inhalation for 13 weeks. The 

compound did not induce an increase in the 

frequency of micronucleated normochromatic erythrocytes in peripheral blood samples (Table El). 
PLATE 1 

Lung of a male F344/N rat exposed to 1.25 mg nickel oxide/m ~ by inhalation 

for 2 years. Squamous differentiation within an alveolar/bronchiolar 

carcinoma. H&E; 105 × 

PLATE 2 

Alveolar/bronchiolar adenoma in the lung of a female F344/N rat exposed to 

2.5 mg nickel oxide/m 3 by inhalation for 2 years. The clusters of neoplastic 

cells fill alveolar spaces and make a mass well demarcated from the 

surrounding alveoli. H&E; 135 × 

PLATE 3 

Subpleural focus of marked chronic inflammation in the lung of a male 

F344/N rat exposed to 2.5 mg nickel oxide/m 3 by inhalation for 2 years. 

Note alveolar spaces fdled with macrophages and other inflammatory cells, 

protein, and cell debris; alveolar septa thickened by inflammatory cell 

infthrates and increased connective tissue; and prominent cuboidal epithelium 

lining air spaces. H&E; 105 x 

PLATE 4 

Benign pheochromocytoma (P) in the medulla of the adrenal gland of a female 

F344/N rat exposed to 2.5 mg nickel oxide/m 3 by inhalation for 2 years. Note 

compression (arrows) of the adrenal cortex. H&E; 35 × 
PLATE 5 

Focus of marked inflammation in the lung of a female B6C3F~ mouse exposed 

to 5 mg nickel oxide/m s by inhalation for 2 years. Note protein, 

macrophages, crystalline rods, and particulate pigment within alveolar spaces. 

H&E; 65 × 

PLATE 6 

Bronchialization (alveolar epithelial hyperplasia) in the lung of a male B6C3Fi 

mouse exposed to 2.5 mg nickel oxide/m s by inhalation for 2 years. Note 

cuboidal cells extending from the terminal bronchiole (B) onto the septa of 

adjacent alveoli. H&E; 135 × 

PLATE 7 

Pigment-laden macrophages (arrows) and pigment within alveolar lumens in 

the lung of a male B6C3Fi mouse exposed to 5 nag nickel oxide/m 3 by 

inhalation for 2 years. H&E; 175 x 

PLATE 8 

Black pigment (arrows) in the bronchial lymph node of a male B6C3Fi mouse 

exposed to 5 nag nickel oxide/m s by inhalation for 2 years. H&E; 25 × 
89 

DISCUSSION AND CONCLUSIONS 

Occupational exposure to nickel oxide may occur 

during refining and processing operations, in high 

temperature operations such as production of stainless 

steel, and in other industrial settings (Doll et al., 

1990). No previous 2-year studies have been reported that establish toxic dose-response relationships or 

toxic effects in organs other than the lung after 

inhalation exposure to nickel oxide in rats or mice. 

In the 16-day (1.2 to 30 mg nickel oxide/m 3, equivalent to 0.9 to 23.6 mg nickel/m 3) and 13-week studies 

(0.6 to I0 mg nickel oxide/m 3, equivalent to 0.4 to 

7.9 mg nickel/m3), there were no chemical-related 

deaths in rats or mice. There were no biologically 

significant chemical-related effects on sperm morphology or vaginal cytology in rats or mice. The 

major toxic effects were in the lung, as evidenced by 

an exposure-related increase in lung weights and the 

occurrence of pigment and inflammation. In both the 

16-day and 13-week studies, pigment and lymphoid 

hyperplasia occurred in the respiratory tract lymph 

nodes. 

Analysis of bronchoalveolar lavage fluid has been 

used in human medicine for diagnosing the type or 

stage of various forms of interstitial lung disease and 

as a rapid in vivo method of evaluation of lung injury 

in toxicologic studies (Henderson et al., 1985). In 

these 13-week studies of nickel oxide, evaluation of 

bronchoalveolar lavage fluid indicated the presence of 

an inflammatory response in the lung of rats exposed 

to 2.5 and 10 mg/m 3 and mice exposed to 10 mg/m 3 

(Benson et al., 1989). This increase was mostly due 

to an increase in the number of alveolar 

macrophages, although numbers of polymorphonuclear leukocytes were also significantly increased. 

Nickel oxide exposure resulted in decreased alveolar 

macrophage phagocytic activity and increased numbers of nucleated cells in lung lavage samples (Haley 

et al., 1990). No nasal lesions were observed in 

either rats or mice in the 13-week studies, which 

contrasts with the findings for the more water-soluble 

nickel compounds (nickel sulfate hexahydrate and 

nickel subsulfide). Toxic effects were more severe 

in rats than in mice. 

In this series of 16-day and 13-week nickel compound studies, nickel oxide was the least toxic, 

followed by nickel subsulfide and nickel sulfate 

hexahydrate, which was the most toxic (Tables 30 

and 31). This is reflected by the increased mortality 

and reduced body weight gain :or body weight loss 

seen with nickel sulfate hexahydrate and nickel 

subsulfide but not nickel oxide. The lung and nasal 

toxicity reflects the relative solubility of the nickel 

compounds in water and biological fluids, with the 

most soluble nickel compound (nickel sulfate hexahydrate) being the most toxic. The soluble nickel 

compounds are thought to be more toxic than the 

insoluble nickel compounds because nickel ions can 

diffuse across the cell membrane and interact with 

cytoplasmic proteins, thereby causing toxicity. 

Alternatively, the water-insoluble nickel compounds 

may be phagocytized and may not cause as extensive 

damage to cytoplasmic components of the alveolar/ 

bronchiolar epithelium (Lee et al., 1993; Costa 

et al., 1994). 

The spectrum of inflammatory lesions in the lungs of 

rats and mice after 13 weeks of exposure to nickel 

oxide was similar to that observed with other particles including nickel sulfate hexahydrate, nickel 

subsulfide, gallium arsenide (NTP unpublished data), 

gallium oxide (NTP unpublished data), and cadmium 

oxide (NTP, 1995). Lymphoid hyperplasia with or 

without inflammation was present in the respiratory 

tract lymph nodes of rats and mice from all of these 

studies. Nickel oxide pigment granules were present 

in the lung and respiratory lymph nodes; although 

pigment granules were not present in the lymph 

nodes of animals from the nickel sulfate hexahydrate, 

nickel subsulfide, or cadmium oxide studies, the 

morphologic appearance of the hyperplasia in the 

paracortical region of the lymph nodes was otherwise 

generally similar in each study. 

In contrast to the findings with nickel sulfate hexahydrate and nickel subsulfide where the amount of 

nickel present in the lungs reached a steady state 

after a 13-week exposure period, the amount of 

nickel present in the lungs continued to increase 

during the 13-week exposure to nickel oxide; a 
90 Nickel Oxide, NTP TR 451 

steady state was not reached. Even though the lungs 

of rats and mice exposed to nickel oxide contained 

more nickel than the lungs of animals exposed to 

nickel sulfate hexahydrate or nickel subsulfide 

(Table 32), the toxic effects were less severe at 

13 weeks. 

The threshold limit value for water-insoluble nickel 

compounds is 1 mg/m 3. In the 13-week studies of 

nickel oxide, a no-observed-adverse-effect level was 

not reached in either rats or mice; the histopathologic 

changes observed at the lowest exposure evaluated 

(0.6 mg nickel oxide/m 3) were subtle and were not 

necessarily indicative of severe lung toxicity. 

The highest exposure concentrations for these 2-year 

studies were limited to 2.5 mg/m 3 for rats and 

5 mg/m 3 for mice, because of the increased severity 

and spectrum of inflammatory lesions in the lung and 

increased lung weights that occurred at the higher 

exposure concentrations in the 13-week studies. The 

nickel compound exposure concentrations for the 

16-day, 13-week, and 2-year nickel studies and their 

nickel equivalents are presented in Table 33. 

Two-year exposure of rats and mice to nickel oxide 

by inhalation had no effect on survival. Mean body 

weights of 2.5 mg/m 3 male and female rats and 

1.25 mg/m 3 female rats were 2% to 10% lower than 

those of controls during the last year of the study. 

Mean body weights of 5 mg/m 3 male and female 

mice were also lower than controls during the last 

year of the study. 

At 7 months and at 15 months, the amount of nickel 

in lungs was similar in males and females. The lung 

nickel burden represents the difference between the 

amount of nickel deposited in the lung and the 

amount removed by the clearance mechanisms. 

Inhaled particles deposited on the mucosal surface of 

the trachea, bronchi, or bronchioles are transported 

up the airways and from the lung through the ciliary 

activity of the respiratory epithelium, while particles 

reaching the alveolar region are phagocytized by 

alveolar macrophages and, to a lesser extent, other 

phagocytic inflammatory cells. Some alveolar 

macrophages migrate to the ciliated epithelium of the 

airways while others cross the alveolar epithelium to 

enter the interstitium and, finally, the lymphatics. 

Phagocytic cells reaching the lymphatics are transported in the lymph to the bronchial and mediastinal 

lymph nodes. In the current studies, the pigment in 

the lymph nodes probably represented the clearance 

of some of nickel oxide from the lungs. Depending 

on the physiochemical properties of the inhaled 

particles, they may be partially or completely 

degraded within phagolysosomes of the macrophages 

and soluble components released from the cell. 

Nickel oxide is relatively insoluble in biologic fluids, 

and a relatively large amount of nickel oxide remains 

in the lung. 

The carcinogenic response in the lung of rats exposed 

to nickel oxide was considered to be chemical related 

because the incidence of lung neoplasms in the 1.25 

and 2.5 mg/m 3 groups exceeded the historical control 

rate at this laboratory, and the effect was observed in 

both males and females. The incidences of lung 

neoplasms in 1.25 mg/m 3 males (6/53, 11%) and 

females (6/53, 11%) and 2.5 mg/m ~ males (4/52, 

8%) and females (5/54, 9%) were significantly 

greater (P < 0.05) than the historical control incidences at Lovelace Inhalation Toxicology Research 

Institute, which are 1.4% (3/210) for males and 

1.9% (4/208) for females. Some of these 

alveolar/bronchiolar neoplasms also had morphologic 

features (prominent scirrhous reaction and squamous 

differentiation) that were different from the spontaneous alveolar/bronchiolar neoplasms in control rats. 

The incidence of alveolar/bronchiolar adenoma in the 

2.5 mg/m 3 group of female mice was significantly 

greater than that of the controls and exceeded the 

historical control range from NTP inhalation studies. 

The incidence of alveolar/bronchiolar adenoma or 

carcinoma (combined) in 1.25 mg/m 3 females was 

significantly greater than that of the controls, and the 

incidences in 1.25 and 2.5 mg/m 3 females exceeded 

the historical control range for inhalation studies. 

However, the incidences of these neoplasms were not 

increased at the highest exposure concentration 

(5 mg/m 3) in females. 

The level of nickel in the lung was measured at 

various time points in the 2-year studies (Table 32), 

and these measurements represent the difference 

between the amount of nickel deposited and the 

amount cleared during a specified time frame. In the 

2-year nickel oxide study, there was 300 to 1,100/zg 

nickel/g lung at 15 months; in the 2-year nickel 

s.ubsulfide study, there was 3 to 7/zg nickel/g lung. 

Thus, the amount of nickel in the lung (as measured 

in these studies) does not predict or parallel the lung 

neoplasm response. The type of nickel compound is 

important in the eventual carcinogenic response, and 

under the conditions of these studies, the nickel 
Discussion and Conclusions 91 

compound that was more rapidly cleared from the 

lungs (nickel subsulfide) produced a stronger carcinogenic response than the nickel compound retained 

in the lungs (nickel oxide). 

The pulmonary and lung neoplasm responses observed in the nickel oxide and nickel subsulfide 

studies were chemically related; these responses 

occurred at exposure concentrations of 1.25 and 

2.5 mg/m 3 nickel oxide and 0.15 and 1 mg/m 3 nickel 

subsulfide. There is no evidence for particle overload; nickel subsulfide levels at 15 months remained 

below 30/zg nickel/g lung, and while lung nickel 

levels increased in the nickel oxide studies to 

1,000/zg/g lung, the levels approached steady state. 

In contrast, rat carcinogenicity studies with other 

relatively nontoxic particles (i.e., titanium dioxide, 

talc, or chromium dioxide) required higher aerosol 

concentrations (10 mg/m 3 or greater) to produce a 

lung neoplasm response. For example, the carcinogenic response in the rat lung reported in the NTP 

talc studies (NTP, 1993a) was observed at 18 mg/m3; 

at this exposure concentration, approximately 25 mg 

talc/g lung was recorded at 18 months and 2 years. 

Similarly in the titantium dioxide inhalation studies in 

rats (Lee et al., 1985), a lung neoplasm response was 

observed only at an exposure level of 250 mg/m 3, 

suggesting that the response may be related to accumulation of nontoxic particles. 

Comparisons could be made of the types of lung 

neoplasms observed after inhalation of va~;ious chemicals at various levels of concentration. For example, 

relatively low levels of exposure to nickel (NTP, 

1996a,b) or cadmium (NTP, 1995) produce neoplastic responses in rats. Intermediate exposure 

levels of diesel exhaust (3.5 to 7 mg/m3; Mauderly 

et al., 1987; Mauderly, 1994) and talc (18 mg/m3; 

NTP, 1993a) produce carcinogenic effects in the 

lungs of rats. Higher exposure concentrations of 

antimony trioxide (45 mg/m3; Groth et al., 1986) and 

titanium dioxide (250 mg/m3; Lee et al., 1985) are 

required to produce similar effects in rats. Comparisons could also be made of the histopathologic nature 

of the lung neoplasms and of the molecular changes 

involved in the response. 

A number of studies have reported sarcomas at the 

site of nickel oxide injection into the muscle or the 

pleural or peritoneal cavity of rodents (Table 3). In 

one inhalation study in hamsters exposed to a nickel 

oxide concentration of 50 mg/m 3, there were extensive nonneoplastic pulmonary lesions but no increase 

in lung neoplasms (Wehner et al., 1975, 1979). 

Intratracheal administration of nickel oxide to female 

rats also caused a significant increase in adenocarcinoma and squamous cell carcinoma of the lung (Pott 

et al., 1987). 

Some generalities dan be made about the comparative 

lung pathology in rats and mice after 2 years of 

exposure to nickel oxide, nickel subsulfide, or nickel 

sulfate hexahydrate. Pigment was observed in the 

lungs and bronchial lymph nodes of rats and mice 

exposed to nickel oxide but not in the lungs of 

animals in the nickel subsulfide or nickel sulfate 

hexahydrate studies. All three studies were similar 

in that mice were less susceptible to proliferative and 

fibrotic lung lesions than rats exposed to the same 

compound. Morphologic features of the proliferative 

lesions in rats exposed to nickel oxide or nickel 

subsulfide were clearly different from spontaneous 

lesions in control rats. Five of the alveolar/ 

bronchiolar carcinomas in rats exposed to nickel 

oxide and four of the alveolar/bronchiolar carcinomas 

and two of the alveolar/bronchiolar adenomas in rats 

exposed to nickel subsulfide had marked squamous 

differentiation. Alveolar/bronchiolar neoplasms in 

exposed mice from all the studies and in rats exposed 

to nickel sulfate hexahydrate had morphologic features similar to those observed in spontaneously 

occurring tumors. 

The nonneoplastic lung lesions in nickel oxide 

exposed rats had evidence of recurrent parenchymal 

damage secondary to inflammation. The resulting 

fibrosis and consolidation were multifocally extensive 

in many nickel oxide exposed rats, differing greatly 

from the minute fibrotic lesions that were occasionally observed in control rats. Similar exposurerelated fibrotic lesions were also observed in nickel 

subsulfide exposed rats but not in nickel sulfate 

hexahydrate exposed rats. There were similar 

incidences, appearances, and severities of spontaneous lesions in the lungs of control rats and mice in 

the three nickel studies. 

With the exception of pigment observed in the nickel 

oxide study, nonneoplastic lesions in the lungs of 

exposed mice were similar in all three nickel compound studies. The components of the inflammatory 

reaction (intra-alveolar protein and macrophages; 

mononuclear inflammatory cells around vessels; and 

multifocal intra-alveolar aggregates of inflammatory 
92 Nickel Oxide, NTP TR 451 

cells) were similar in exposed mice in all three 

studies. Inflammatory foci with .neutrophils and 

necrotic cell debris were relatively common in mice 

exposed to nickel sulfate hexahydrate, while inflammatory foci in mice exposed to nickel oxide and 

nickel subsulfide were predominantly mononuclear 

cells with little evidence of necrotic cell debris. 

The inflammatory lesions in the lung were similar to 

those reported in rodents exposed to talc (NTP, 

1993a), cadmium compounds (Aufderheide et al., 

1989), titanium dioxide (Lee et al., 1985), chromium 

dioxide (Lee et al., 1988), antimony trioxide and 

antimony ore concentrate (Groth et al., 1986), or 

volcanic ash (Wehner et al., 1986). Aerosols of each 

of these particulate substances were reported to elicit 

pulmonary inflammation (characterized primarily by 

the accumulation of alveolar macrophages), hyperplasia, and, in some cases, squamous metaplasia of the 

alveolar epithelium and fibrosis. 

In the NTP studies, more chemical-related lung 

neoplasms were observed in nickel oxide and nickel 

subsulfide exposed rats than in mice. In cadmium 

carcinogenicity inhalation studies performed at the 

Fraunhofer Institute, cadmium induced alveolar/ 

bronchiolar neoplasms in rats but not in mice 

(Aufderheide et al., 1989; Heinrich et al., 1989; 

Thiedemann et al., 1989; Glaser et al., 1990; 

Takenaka et al., 1990). In the series of approximately 450 chemical studies by NTP, the rat is more 

susceptible to the formation of lung neoplasms after 

exposure to metals (e.g., nickel oxide, nickel 

subsulfide), while the mouse is more susceptible to 

the formation of lung neoplasms after exposure to 

epoxide-forming chemicals (e.g., coumarin, NTP, 

1993b; benzene, NTP, 1986; glycidol, NTP, 1990a). 

The mouse is also more susceptible than the rat to 

formation of lung neoplasms after exposure to 

halogenated chemicals (2,2-bis(bromomethyl)- 

1,3-propanediol, NTP, 1996c; 1,2-dibromo-3-chloropropane, NTP, 1982a; 1,2-dibromomethane, NCI, 

1978a, NTP 1982b; 2,3-dibromo-l-propanol, NTP, 

1994; 1,2-dichloroethane, NCI, 1978b; and tris(2,3- 

dibromopropyl)phosphate, NCI, 1978c). 

The morphologic types of lung neoplasms induced by 

various particulates in rodents vary. In the talc 

studies, a significant increase in alveolar/bronchiolar 

neoplasms was observed only in female rats (NTP, 

1993a), and the type of neoplasm was similar to that 

observed in the present nickel oxide studies. Other 

chemicals producing alveolar/bronchiolar neoplasms 

in rats after inhalation exposure include antimony 

trioxide (Groth et al., 1986) and cadmium 

(Aufderheide et al., 1989). Alternatively, most of 

the pulmonary neoplasms induced by quartz (Dagle 

et al., 1986), volcanic ash (Wehner et al., 1986), or 

chromium dioxide (Lee et al., 1988) were squamous 

cell (epidermoid) carcinomas. In refinery workers, 

pulmonary neoplasms attributed to nickel exposure 

have been classified primarily as squamous cell 

carcinomas with fewer anaplastic carcinomas and 

adenocarcinomas (Sunderman et al., 1989). 

Lung tissue specimens from 39 nickel refinery 

workers showed increased lung nickel levels 

(Andersen and Svenes, 1989). The average nickel 

concentration for workers in roasting and smelting 

operations was 330 ± 380/xg nickel/g dry lung 

weight; for workers in electrolysis departments, 

34 _+ 48 /zg/g; and for lung tissue from unexposed 

people, 0.76 ± 0.39 /zg/g. Dry lung represents 

approximately 20% "wet" lung weight (Henderson 

and Escobedo, 1976). Workers who were diagnosed 

with lung cancer (14 cases) had the same lung nickel 

concentrations at autopsy as nickel workers 

(25 cases) who died of other causes. The lung nickel 

concentration was independent of smoking habits. 

Anderson and Svenes (1989) felt that the retained 

nickel in the lung was probably nickel oxide because 

an earlier study using energy dispeisive X-ray 

analysis did not detect sulfides (e.g., Ni3S2) in the 

lung. This study also found that lung cancer 

occurred in workers from the electrolysis department 

(8/24) as well as those from the roasting and smelting 

operations (6/15) even though those from the electrolysis department had lower lung nickel levels. 

Nasopharyngeal carcinoma in humans has been 

attributed to nickel exposure. The preponderance of 

these sinonasal neoplasms in humans have been 

classified as anaplastic, undifferentiated, or squamous 

cell carcinoma (Sunderman et al., 1989). In the 

present rodent studies, the olfactory epithelium, 

rather than the respiratory or squamous mucosa, was 

the target site for chemical-related toxicity. Although 

the atrophic changes were present in the olfactory 

epithelium of rats and mice in the 13-week and 

2-year studies of nickel subsulfide and nickel sulfate 

hexahydrate, the nasal mucosa was not affected in the 

nickel oxide study. Furthermore, after 2 years, there 

was no evidence of a chemical-related increase in the 

incidences of proliferative lesions in the nasal cavity 
Discussion and Conclusions 93 

of rats or mice exposed to any of the three nickel 

compounds tested. 

The increase in proliferative lesions of the adrenal 

medulla in male and female rats was considered to be 

chemical related. In male rats, the overall increase 

in benign and malignant pheochromocytomas was 

related primarily to an increase in malignant pheochromocytomas. In female rats, only the incidence 

of benign pheochromocytoma was increased, but the 

number of rats with bilateral pheochromocytoma and 

the number with hyperplasia were also increased in 

the 5 mg/m 3 group. A chemical-related increase in 

pheochromocytomas was also observed in male and 

female rats exposed to nickel subsulfide and in male 

and female rats exposed to talc (NTP, 1993a). 

However, similar increases were not observed in rats 

exposed to nickel sulfate hexahydrate or to other 

particulates including antimony trioxide or trisulfide 

(Groth et al., 1986) and titanium dioxide (Lee et al., 

1988). Chemical-related increases in the incidences 

of pheochromocytoma have also been reported in rats 

exposed by inhalation to bromoethane (NTP, 1990b) 

and orally to 2-mercaptobenzothiazole (NTP, 1988) 

and r.eserpine (NCI, 1982). The mechanism for this 

increased incidence of adrenal medulla neoplasms is 

not known. There was no morphologic evidence that 

the pigment granules of phagocytized nickel oxide 

reached the adrenal gland, suggesting that the mechanism for the carcinogenic response in the adrenal 

gland may be related to factors other than direct 

interaction of the chemical with adrenal cells. 

CONCLUSIONS 

Under the conditions of these 2-year inhalation 

studies, there was some evidence of carcinogenic 

activity* of nickel oxide in male F344~/N rats based 

on increased incidences of alveolar/bronchiolar 

adenoma or carcinoma (combined) and increased 

incidences of benign or malignant pheochromocytoma 

(combined) of the adrenal medulla. There was some 

evidence of carcinogenic activity of nickel oxide in 

female F344/N rats based on increased incidences of 

alveolar/bronchiolar adenoma or carcinoma (combined) and increased incidence~ of benign pheochromocytoma of the adrenal medulla. There was no 

evidence of carcinogenic activity of nickel oxide in 

male B6C3FI mice exposed to 1.25, 2.5, or 5 mg/m 3. 

There was equivocal evidence of carcinogenic activity 

of nickel oxide in female B6C3Ft mice based on the 

marginally increased incidences of alveolar/ 

bronchiolar adenoma in 2.5 mg/m 3 females and of 

alveolar/bronchiolar adenoma or carcinoma (combined) in 1.25 mg/m 3 females. 

Exposure of rats to nickel oxide by inhalation for 

2 years resulted in inflammation and pigmentation in 

the lung, lymphoid hyperplasia and pigmentation in 

the bronchial lymph nodes, and hyperplasia of the 

adrenal medulla (females). Exposure of mice to 

nickel oxide by inhalation for 2 years resulted in 

bronchialization, proteinosis, inflammation, and 

pigmentation in the lung and lymphoid hyperplasia 

and pigmentation in the bronchial lymph nodes. 

* Explanation of Levels of Evidence of Carcinogenic Activity is on page 10. A summary of the Technical Reports Review Subcommittee 

comments and the public discussion on this Technical Report appears on page 12. 
94 Nickel Oxide, NTP TR 451 

o 

o ~. 

~ I ~. ~ I ~ 

~ I ~ ,,~ I ~ 

~ I ~ ~ I ~ 

~ I ~. ~ l -. 

~ I ~ ~ l ~ 

~ I ~ 

~ I ~ 

~ t ~ 

~ I ,~ 

~ I ~ 

~ I ~ 

~ I ~ 

~ I ~ 

~ I ~ 

I~ ~ 

~ i.~ 

o 

~ ~O 
Discussion and Conclusions 95 

..~ 

Z 

[ 

o~ 

i 

o~ 

0 

I ~ 

~ e ~ 

~ ~ .-~ 

~u ~ 

~e ~ 

~Y_ ~ 

~ ~ 

~ ~ 

..~ ~ 

~ < 

--~--~--~--_ 

~--_ ~--~ 

~ ~ ~ v 

- ,~- ,6~ -,~ ~ 

~ ~ 

_=~o ~o - 

~ ~ ~ 

o~o ~ ~ = -~o o 

~ ~ 

v 

~<--~=~= ~ 

Z Z 
96 

Nickel Oxide, NTP TR 451 

..~ 

m 

i 

o 

< 

~.~ 

-~ 

~.~ 

o~ 

m~ 

~ ~ 

~ 

0 

~ ~ 

~ - 

~ ~ 

~ ~ 

0 ~ 

~ ~ 

~~0~ ~ 

~M~o e~ ~ o 

~ ~ ~ ~ 

~.o o o ~.~. o 

~ ~.~ 

0 ~ ~ ~ ~ ~ 

~ ~ 

~ ~ o~ ~ .o o 

~ ~ ~ ~ ~ ~ 

~ ~ ~ ~ o ~o~ ~ . -o o - -~ ~o ~ 

~ ~ ~ ~ 

o ~ ~o ~ o ~ 

~ ~ ~ ~ 

F 

~o ~ ~ ~ o~ ~ ~ o 0 ~ 

~ ~ ~ ~ ~ 

~ ~ ~o 

~ ~ ~ ~ o o o 

~ ~ ~ 

~ ~ o o o o o o 

~ ~ ~ O~ 0 ~.o~. 0 0 ~.o 0 

0 ~ ~ tOO ~ ~ ~ ~ ~ 

~ ~ ~ ~ ~ 

~ ~ ~ ~o ~o ~ ~ ~ 

~ ~ ~ 

~ ~ ~ ~ ~ ~0 0 0 ~ ~ ~ ~ ~ 

~ ~ ~ 

~ ~ • 0 0 ~ 0 0 

~ ~ ~ 

~ ~ ~ o ~ ~ o ~ 

~ ~ ~ 0 

~ ~ z z 
Discussion and Conclusions 97 

.~ 

.g 

~,~ ~1~ 

u 

Z 

Z 

m 

u 

~g 

~.o m~m~ ~ 

~ ~ ~ 

o~ o ~ ~o~ o 

~ ~ 

~ ~ ~ 

*~ ~ 

~ ~ ~ ~ ~ 

~ 

~ ~ ~ 

~ ~ 

~ ~ ~ ~ ~ ~ 

~ ~ 

o~o o . o o~ . 

~ ~ 

~ ~ 

~ ~ ~ ~ ~ ~ ~ 

~ o~ ~ ~o ~ ~ o ~ 

~ ~ ~ 

~~ ~ ~ 

~. ~ ~ ~. ~ 

~ ~ 

~. ~ ~ ~ ~ ~ 

~ ~ ~ ~ ~. ~ 

~ ~ ~ ~ ~ ~ ~ 

0 m ~~ ~.0 ~ 

- ~ ~ 

N ~ ~ ~ ~ ~ ~ ~ 

o ~~o ~ .o ~ 

~ ~ ~ 

~ o ~ 

~ o 

~ ~ o o o o o o o 

~ 0 

~ o ~ o o .~ ~ 

o o 

.. ,_. ~, ,~,~ ~, ~ .~0 

.~ ~ ~ 

~.~ ~ ~_='~..~~ ~ - .=~.~.~ ~ 

~ ~ ~>~~>~ 

~ ~ ~ ~ ~ ~ ~ ~ ~ 

~ ~ ~ ~ ~ ~ ~ ~ ~ ~~ ~ ~ ~ ~~~ ~ ~ 

.~ ~ 0 0 

~ < z Z 
98 Nickel Oxide, NTP TR 451 

Z 

m 

.N 

Z 

,~ 

.~ 

Z 

0 

0 

~ 0 

°~ Z 

~ O 

~g 

~ I ~ 

v 

~2~.~.~ ~. 

~ ~ 

v ~ ~ 

~ v 

v v 

v ~ 

v ~ 

v 

v ~ 

~ ~ ~ ~ ~ ~, ~ 

~ v 

.~ ~ ~ ~ 

-- ~ 6 ~ ~ ~ 

~~ ~ ~ 

~ ~ .~~-~.~.~ ~ ~ .~ 

"~'~ ?~ • ~ ..~ N ~ 

~ ~ ~ ~ - . 

~'~ ~ ~'~ ~ ~~ ~ 

~ ~ ~ ~ ~ ~g~ ** ..... 

. ~~ ~ ~ g ~ ~ ~ ~ ~ ~ ~ 

~ ~ ~ z ~ 

z~ 

~ ii 

~ ~ ii 

~ ~m 

,~'~ 

~ .~ n 

:~ .~ ~ 

~ .~ 

~ ~ 

~ ~ 

~ . ~ 

~ ~ 

~ .~ .~ 

• ~ N ~ ~ 

~ ~ 

~ ~ 

~ N -~ ~ 

~ "~ 

~ ~ 

~ ~~ 

~ ~ 

~ ~ ~.~ 

~ ~ ~ 

~ ~ 

~ ~.~!~ 

~ ~ 

N ~ ~-- ~.~ 

~ ~Z 

~ ~ ~ ~ ~ 
Discussion and Conclusions 99 

% 

,~ 

~I~ ~ 

,~.~I" ,.~, 

~i ~ 

~I ~. ~. 

~I ~ ~. 

~ ~ 

~ ~ 

~ ~ ~1 , ~ 

~ ~ 

~ N ~1" ~ 

~1" 

I I I I 

I I I I 

"~1 I I 

I I 

I I I I 

1 I 

I I 
100 

~ .~ 

~ ~2 ~ ~ 

t~ ~ ~ 

~, ~. ~ ~ 

~ ~ 

~ ~ ~ 

~ ~ 

~ ~ 

~ I I I I 

~ ~ 

-~ 

~ ~ ~ 

~ ~ ~ 

~ 

~ ~ ~ 

~ ~ 

~ 

~ I I I I 

• ~ ~ ~ 

~ ~ 

~ 

~ ~ 

~ ~ ~ ~ 

~ 

~ I I ~ 

~ I I I I 

~ N ~ ~ 

~ ~ ~~ ~ 

i ~ ~~ 

~ ° 

I I I I 

I I 

I I 

~ 8 

~ o ~ 

e~ ~ z 

..~ 

I~ 

,.~ 

..~ 

a 

N 

I~ 

M 

• . ~.~ 

~.~ 

~ 

~ ~ 

,5~ 

~ -.~ 

"~ ~ 

~.~ 

~ 

~~ 

~ ~-~' 

~ 

~ 

N-~ 

N.~ 

~ ~ 

~ 

~-~ ~i 

~ ~ 

Nickel Oxide, NTP TR 451 
Discussion and Conclusions 101 

TABLE 33 

Comparison of Exposure Concentrations in the 16-Day, 13-Week, and 2-Year Studies 

of Nickel Sulfate Hexahydrate, Nickel Subsulfide, and Nickel Oxide a 

Amount of Compound Amount of Nickel 

16-Day Studies 

Nickel Sulfate 

Hexahydrate (22.3% Ni) 

Nickel Subsulfide (73.3% Ni) 

Nickel Oxide (78.6% Ni) 

0, 3.5, 7, 15, 30, 60 

0, 0.6, 1.2, 2.5, 5, 10 

0, 1.2, 2.5, 5, 10, 30 

0, 0.7, 1.4, 3.1, 6.1, 12.2 

0, 0.44, 0.8~, 1.83, 3.65, 7.33 

0, 0.9, 2.0, 3.9, 7.9, 23.6 

13-Week Studies 

Nickel Sulfate 

Hexahydrate (22.3% Ni) 

Nickel Subsulfide (73.3% Ni) 

Nickel Oxide (78.6% Ni) 

0, 0.12, 0.25, 0.5, i, 2 

0, 0.15, 0.3, 0.6, 1.2, 2.5 

0, 0.6, 1.2, 2.5, 5, 10 

0, 0.03, 0.06, 0.11, 0.22, 0.44 

0, 0.11, 0.22, 0.44, 0.88, 1.83 

0, 0.4, 0.9, 2.0, 3.9, 7.9 

2-Year Studies 

Nickel Sulfate 

Hexahydrate (22.3% Ni) 

Rats 

Mice 

Nickel Subsulfide (73.3% Ni) 

Rats 

Mice 

0, 0.12, 0.25, 0.5 

0, 0.25, 0.5, 1 

0, 0.03, 0.06, 0.11 

0, 0.06, 0.11, 0.22 

0, 0.15, 1 0, 0.11, 0.73 

0, 0.6, 1.2 0, 0.4.4, 0.88 

Nickel Oxide (78.6% Ni) 

Rats 0, 0.62, 1.25, 2.5 0, 0.5, 1.0, 2.0 

Mice 0, 1.25, 2.5, 5 0, 1.0, 2.0, 3.9 

a Amounts of nickel and nickel compounds are expressed in mg/m ~. Occupational exposure limits in the United States: 1 mg Ni/m ~ for 

nickel metals, 0.1 mg Ni/m 3 for soluble nickel compounds. 
102 Nickel Oxide, NTP TR 451 

% 

m 

m 

Z 

o 

o 

"~1 ~ 

~1 

~1 

~.~1 

~g 

I ~ ~. ~ o~-~..~ 

~ 0~1 

I ~ ~ooo 

~'~ ~. ~'~o 

o ,,-; e,i 

~ "~ 

N 

N 

I ~ ~ z ~ o~ 

~ "~ 

~ ~ 

• ~ ~ 

.~ ~ ~ .~ 

~ ~ .~ "~ ~ 

• ~~ ~ 2 ~ 

~ ~ . ~ 

~ ~ ~ ~ .~ 

• ~ ~ ~ ~ ~ ~ 

N~ ~ ~ ~ ~" N ~ a 

~e • ~ ~ 

~ ~-.g ~ 

~ ~ ~ ~ 

.~ ~ 

~ ~ ~ ~" ~ 

~ ~ , ~ ~ I~ ~ ~ i ~< 

~ < < 

~o~ 

~.~-~ 

~o~ 

z ~ 

~ Q ~ 

N I~ ~ o 

o 

Z 
Discussion and Conclusions 103 

v 

m 

o 

o 

~' I ~ 

~ I ~ 

~.~ 

~ z 

-- "~ 

.~ ~ ~ 

~ ~ ~;.~ 

~ ~ '~ ~ ~ .~ 

e.~ ~ 

~ ~ 

- ~ 

~ ~ ~.~ ~ ~ 

~ ~, i~ I ~: 

~ ~ 

z 

~ ~ ~ ~ o 

~ < ~ ~ ~a 

~ ~ .~ o o ~ N~ 

~_-~ ~ ~ ~ ~ ~ 

~ ~ ~ ~ ~ 

a~ 

~ ~ ~ ~ ~ 

~ ~ ~ ~.g ~ ~.~ 

-~ ~-~ 

8 ~ ~ ~ ~ ~ e 

~ ~.~ ~ N~=~= ~'~ ~ ~ 

~ ~ ~ ~-~ ~ .~ 

~ e~ ~~ 

~ ~ 

~ ~ 

z 
104 Nickel Oxide, NTP TR 451 

Z 

m 

.~. 

Z 

r~ 

.~ .N 

Z 

.~ 

~1~ 

..~ 

,4 

..~ 

N 

~ 

m~ 

~ 

~ 

Z 

~ < 

O 

< 

Z 

Z 

z 
Discussion and Conclusions 105 

~ ~ ~ 

~g ~,~ 

~,~ 

.~. 

~ o 

.~ 

~,~ 

N 

N ~ 

~ ~ 

~ ~ 

~ ~ 

N 

~ 

~ a 

~ ~ 

~e 

. . 

N ~ 

~1 

~ 

~ 

Z 

o 

o 

*** 

~ I ~. 

~ ~ 

~ ~ 

I ~.~. ~ ~ 

~ ~ 

• ~ ~ 

~ ~ 

o ~ .~ ~ 

~ ~ ~ 

~ ~ ~ ~ 

~ ~ ~ ~ .~ ~ ~ .~ ~ 

• ~ ~ ~ ~ 

~ ~N ~ ~ ~ ~ 

~.~ ~ ~.~ 

~ ~ ~~ 

~ ~~ I~ ~a ~ e 

~ ~ ~ 

Z 

~ ~ 0 0 

,~ ~e~ 

~ ~ ~ 

. ~'~NN 

~ -~ ~ 

e ~e~ 

~ ~ ~ 

~ ~ 

~ ~ 

~ ~# 

N ~ ~ ~ 

~ 

~q~ ~ 

"N ~" 2 "~'~ ~ vl ~ ~ 

~~ 

~ ~ ~ ~ ~ ~ 
106 Nickel Oxide, NTP TR 451 
107 

REFERENCES 

Adkins, B., Jr., Richards, J.H., and Gardner, D.E. 

(1979). Enhancement of experimental respiratory 

infection following nickel inhalation. Environ. Res. 

20, 33-42. 

Agency for Toxic Substances and Disease Registry 

(ATSDR) (1992). Toxicological profile for nickel 

(TP-92/14). U.S. Department of Health and Human 

Services, Public Health Service, Agency for Toxic 

Substances and Disease Registry. 

Albert, D.M., Gonder, J.R., Papale, J., Craft, J.L., 

Dohtman, H.G., Reid, M.C., and 

Sunderman, F.W., Jr. (1980). Induction of ocular 

neoplasms in Fischer rats by intraocular injection of 

nickel subsulfide. In Nickel Toxicology (S.S. Brown 

and F.W. Sunderman, Jr., Eds.), pp. 55-58. 

Academic Press, London. 

Arnacher, D.E., and Paillet, S.C. (1980). Induction 

of trifluorothymidine-r~sista.nt mutants by metal ions 

in L5178Y/TK ÷z cells. Mutat. Res. 78, 279-288. 

Ambrose, A.M., Larson, P.S., Borzelleca, J.F., and 

Hennigar, G.R., Jr. (1976). Long term toxicologic 

assessment of nickel in rats and dogs. J. Food Sci. 

Technol. 13, 181-187. 

American Conference of Governmental Industrial 

Hygienists (ACGIH) (1993). 1993-1994 Threshold 

Limit Values for Chemical Substances and Physical 

Agents and Biological Exposure Indices, Cincinnati, 

OH. 

American Society of Testing and Materials (ASTM) 

(1974). Annual Book of ASTM Standards, Part 12, 

p. 426, Designation A636-70. 

Andersen, I., and Svenes, K.B. (1989). 

Determination of nickel in lung specimens of thirtynine autopsied nickel workers. Int. Arch. Occup. 

Environ. Health 61, 289-295. 

Arlauskas, A., Baker, R.S.U., Bonin, A.M., 

Tandon, R.K., Crisp, P.T., and Ellis, J. (1985). 

Mutagenicity of metal ions in bacteria. Environ. Res. 

36, 379-388. 

Armitage, P. (1971). Statistical Methods in Medical 

Research, pp. 362-365. John Wiley and Sons, New 

York. 

Arrouijal, F.Z., Hildebrand, H.F., Vophi, H., and 

Marzin, D. (1990). Genotoxic activity of nickel 

subsulphide a-Ni3S 2. Mutagenesis 5, 583-589. 

Arrouijal~ F.Z., Marzin, D., Hildebrand, H.F., 

Pestel, J., and Haguenoer, J.M. (1992). Differences 

in genotoxic activity of ot-NiaS 2 on human 

lymphocytes from nickel-hypersensitized and nickelunsensitized donors. Mutagenesis 7, 183-187. 

Ashby, J., and Tennant, R.W. (1991). Definitive 

relationships among chemical structure, 

carcinogenicity, and mutagenicity for 301 chemicals 

tested by the U.S. NTP. Mutat. Res. 257, 229-306. 

Aufderheide, M., Thiedemann, K.-U., Riebe, M., 

and Kohler, M. (1989). Quantification of 

proliferative lesions in hamster lungs after chronic 

exposure to cadmium aerosols. Exp. Pathol. 37, 

259-263. 

Bache, C.A., Lisk, D.J., Doss, G.J., Hoffman, D., 

and.Adams, J.D. (1985). Cadmium and nickel in 

mainstream particulates of cigarettes containing 

tobacco grown on a low-cadmium soil-sludge 

mixture. J. Toxicol. Environ. Health 16, 547-552. 

Bennet, B.G. (1984). Environmental nickel pathways 

to man. In Nickel in the Human Environment 

(F.W. Sunderman, Jr., A. Aitio, A. Berlin, 

C. Bishop, E. Buringh, W. Davis, M. Gounar, 

P.C. Jacquignon, E. Mastromatteo, J.P. Rigaut, 

C. Rosenfeld, R. Saracci, and A. Sors, Eds.), IARC 

Scientific Publications No. 53, pp. 487-496. Oxford 

University Press, Oxford. 
108 Nickel Oxide, NTP TR 451 

Benson, J.M., Henderson, R.F., McClellan, R.O., 

Hanson, R.L., and Rebar, A.H. (1986). 

Comparative acute toxicity of four nickel compounds 

to F344 rat lung. Fundam. Appl. Toxicol. 7, 

340-347. 

Benson, J.M., Carpenter, R iL., Hahn, F.F., 

Haley, P.J., Hanson, R.L., Hobbs, C.H., Pickrell, 

J.A., and Dunnick, J.K. (1987). Comparative 

inhalation toxicity of nickel subsulfide to F344/N rats 

and B6C3F~ mice exposed for 12 days. Fundam. 

Appl. Toxicol. 9, 251-265. 

Benson~ J.M., Burt, D.G., Cheng, Y.S., Hahn, F.F., 

Haley, P.J., Henderson, R.F., Hobbs, C.H., 

Pickrell, J.A., and Dunnick, J.K. (1989). 

Biochemical responses of rat and mouse lung to 

inhaled nickel compounds. Toxicology 57, 255-266. 

Benson, J.M., Barr, E.B., Bechtold, W.E., 

Cheng, Y.-S., Dunnick, J.K., Eastin, W.E., 

Hobbs, C.H., Kennedy, C.H., and Maples, K.R. 

(1994). Fate of inhaled nickel oxide and nickel 

subsulfide in F344/N rats. Inhalat. Toxicol. 6, 

167-183. 

Berry, J.P., Poupon, M.F., Judde, J.G., 

Pot-Deprun, J., Dewally, D., Chouroulinkov, I., and 

Galle, P. (1984). Electron microprobe in vitro study 

of interaction of carcinogenic nickel compounds with 

tumour ceils. In Nickel in the Human Environment 

(F.W. Sunderman Jr., A. Aitio, A. Berlin, 

C. Bishop, E. Buringh, W. Davis, M. Gounar, 

P.C. Jacquignon, E. Mastromatteo, J.P. Rigaut, 

C. Rosenfeld, R. Saracci, and A. Sors, Eds.), IARC 

Scientific Publications No. 53, pp. 153-164. Oxford 

University Press, Oxford. 

Biggart, N.W., and Costa, M. (1986). Assessment 

of the uptake and mutagenicity of nickel chloride in 

Salmonella tester strains. Mutat. Res. 175, 209-215. 

Bingham, E., Barkley, W., Zerwas, M., 

Stemmer, K., and Taylor, P. (1972). Responses of 

alveolar macrophages to metals: I. Inhalation of lead 

and nickel. Arch. Environ. Health 25, 406-414. 

Boldt, J.R., Jr. (1967). The Winning of Nickel. Its 

Geology, Mining, and Extractive Metallurgy 

(P. Queneau, Ed.). Longmans Canada Limited, 

Toronto. 

Boorman, G.A., Montgomery, C.A., Jr., 

Eustis, S.L., Wolfe, M.J., McConnell, E.E., and 

Hardisty, J.F. (1985). Quality assurance in 

pathology for rodent carcinogenicity studies. In 

Handbook of Carcinogen Testing (H.A. Milman and 

E.K. Weisburger, Eds.), pp. 345-357. Noyes 

Publications, Park Ridge, NJ. 

Boysen, M., Solberg, L.A., Torjussen, W., 

Poppe, S., and Hogetveit, A.C. (1984). Histological 

changes, rhinoscopical findings and nickel 

concentration in plasma and urine in retired nickel 

workers. Acta Otolaryngol. 97, 105-115. 

Bridge, J.C. (1933). Annual report of the chief 

inspector of factories and workshops for the year 

1932, pp. 103-104. His Majesty's Stationery Office, 

London. 

Brown, S.S., and Sunderman, F.W., Jr., Eds. 

(1985). Progress in Nickel Toxicology. Proceedings 

of the Third National Conference on Nickel 

Metabolism and Toxicology. Blackwell Scientific 

Publications, Oxford. 

Bryan, S.E. (1981). Heavy metals in the cell's 

nucleus. In Metal Ions in Genetic Information 

Transfer (G.L. Eichhorn and L.G. Marzili, Eds.), 

pp. 87-101. Elsevier, New York. 

Carvalho, S.M.M., and Ziemer, P.L. (1982). 

Distribution and clearance of 63Ni administered as 

63NIC12 in the rat: Intratracheal study. Arch. 

Environ. Contam. Toxicol. 11, 245-248. 

Chashschin, V.P., Artunina, G.P., and Norseth, T. 

(1994). Congenital defects, abortion and other health 

effects in nickel refinery workers. Sci. Total 

Environ. 148, 287-291. 

Christie, N.T. (1989). The synergistic interaction of 

nickel (II) with DNA damaging agents. Toxicol. 

Environ. Chem. 22, 51-59. 
References 109 

Christie, N.T., and Katisifis, S.P. (1990). Nickel 

carcinogenesis. In Biological Effects of Heavy Metals 

(E.C. Foulkes, Ed.), Vol. II, Chapter 4, pp. 95-128. 

CRC Press, Boca Raton. 

Christie, N.T., Chin, Y.G., Snow, E.T., and 

Cohen, M. (1991). Kinetic analysis of Ni (II) effects 

on DNA replication by polymerase or. J. Cell. 

Biochem. 15D, 114. 

Ciccarelli, R.B., and Wetterhahn, K.E. (1982). 

Nickel distribution and DNA lesions induced in rat 

tissues by the carcinogen nickel carbonate. Cancer 

Res. 42, 3544-3549. 

Code of Federal Regulations (CFR) 21, Part 58. 

Conway, K., and Costa, M. (1989). Nonrandom 

chromosomal alterations in nickel-transformed 

Chinese hamster embryo ceils. Cancer Res. 49, 

6032-6038. 

Coogan, T.P., Latta, D.M., Snow, E.T., and 

Costa., M. (1989). Toxicity and carcinogenicity of 

nickel compounds. Crit. Rev. Toxicol. 4, 341-384. 

Costa, M. (1991). Molecular mechanisms of nickel 

carcinogenesis. Annu. Rev. Pharmacol. Toxicol. 31, 

321-337. 

Costa, M., and Heck, J.D. (1983). Influence of 

surface charge and dissolution on the selective 

phagocytosis of potentially carcinogenic particulate 

metal compounds. Cancer Res. 43, 5652-5658. 

Costa, M., and Mollenhauer, H.H. (1980). 

Phagocytosis of particulate nickel compounds is 

related to their carcinogenic activity. In Nickel 

Toxicology (S.S. Brown and F.W. Sunderman, Jr., 

Eds.), pp. 43-46. Academic Press, London. 

Costa, M., Heck, J.D., and Robison, S.H. (1982). 

Selective phagocytosis of crystalline metal sulfide 

particles and DNA strand breaks as a mechanism for 

the induction of cellular transformation. Cancer Res. 

42, 2757-2763. 

Costa, M., Zhitkovich, A., Taioli, E., and 

Toniolo, P. (1993). Preliminary report on a simple 

new assay for DNA-protein cross-links as a 

biomarker of exposures experienced by welders. J. 

Toxicol. Environ. Health 40, 217-222. 

Costa, M., Zhuang, Z., Huang, X., Cosentino, S., 

Klein, C.B., and Salnikow, K. (1994). Molecular 

mechanisms of nickel carcinogenesis. Sci. Total 

Environ. 148, 194-199. 

Cotelle, N., Tr6moli~res, E., Bernier, J.L., 

Catteau, J.P., and H6nichart, J.P. (1992). Redox 

chemistry of complexes of nickel (II) with some 

biologically important peptides in the presence of 

reduced oxygen species: An ESR study. J. Inorg. 

Biochem. 46, 7-15. 

Courtin, G.M. (1994). The last 150 years: A 

history of environmental degradation in Sudbury. 

Sci. Total Environ. 148, 99-102. 

Cox, D.R. (1972). Regression models and lifetables. J. R. Stat. Soc. B34, 187-220. 

Crawford, B.D. (1985). Perspectives on the somatic 

mutation model of carcinogenesis. In Advances in 

Modern Environmental Toxicology: Mechanisms and 

Toxicity of Chemical Carcinogens and Mutagens 

(M.A. Mehlman, W.G. Flamm, and R.J. Lorentzen, 

Eds.), pp. 13-59. Princeton Scientific Publishing Co. 

Inc., Princeton, NJ. 

Dagle, G.E., Wehner, A.P., Clark, M.L., and 

Bushbom, R.L. (1986). Chronic inhalation exposure 

of rats to quartz. In Silica, Silicosis, and Cancer: 

Controversy in Occupational Medicine 

(D.F. Goldsmith, D.M. Winn and C.M. Shy, Eds.), 

pp. 255-266. Praeger Scientific, NY. 

Damjanov, I., Sunderman, F.W., Jr., Mitchell, J.M., 

and Allpass, P.R. (1978). Induction of testicular 

sarcomas in Fisher rats by intratesticular injection of 

nickel subsulfide. Cancer Res. 38, 268-276. 

Daniel, M.R. (1966). Strain differences in the 

response of rats to the injection of nickel sulphide. 

BL J. Cancer 20, 886-895. 
110 Nickel Oxide, NTP TR 451 

Dieter, M.P., Jameson, C.W., Tucker, A.N., 

Luster, M.I., French, J.E., Hong, H.L., and 

Boorman, G.A. (1988). Evaluation of tissue 

disposition, myelopoietic, and immunologic responses 

in mice after long-term exposure to nickel sulfate in 

the drinking water. J. Toxicol. Environ. Health 24, 

357-372. 

Dinse, G.E., and Haseman, J.K. (1986). Logistic 

regression analysis of incidental-tumor data from 

animal carcinogenicity experiments. Fundam. Appl. 

Toxicol. 6, 44-52. 

Dtnse, G.E., and Lagakos, S.W. (1983). Regression 

analysis of tumour prevalence data. Appl. Statist. 

32, 236-248. 

Doll, R. (1958). Cancer of the lung and nose in 

nickel workers. Br. J. Ind. Med. 15, 217-223. 

Doll, R. (1984). Nickel exposure: A human health 

hazard. In Nickel in the Human Environment 

(F.W. Sunderman, Jr., A. Aitio, A. Berlin, 

C. Bishop, E. Buringh, W. Davis, M. Gounar, 

P.C. Jacquignon, E. Mastromatteo, J.P. Rigaut, 

C. Rosenfeld, R. Saracci, and A. Sors, Eds.), IARC 

Scientific Publications No. 53, pp. 3-22. Oxford 

University Press, Oxford. 

Doll, R., Andersen, A., Cooper, W.C., 

Cosmatos, I., Cragle, D.L., Easton, D., 

Enterline, P., Goldberg, M., Metcalfe, L., 

Norseth, T., Peto, J., Rigaut, J-P., Roberts, R~, 

Seilkop, S.K., Shannon, H., Speizer, F., 

Sunderman, F.W., Jr., Thornhill, P., Warner, J.S., 

Weglo, J., and Wright, M. (1990). Repor~ of the 

international committee on nickel carcinogenesis in 

man. Scand. J. Work Environ. Health 16, 1-82. 

Dostal, L.A., Hopfer, S.M., Lin, S.-M., and 

Sunderman, F.W., Jr. (1989). Effects of nickel 

chloride on lactating rats and their suckling pups, and 

the transfer of nickel through rat milk. Toxicol. 

Appl. Pharmacol. 101, 220-231. 

Dunn, O.J. (1964). Multiple comparisons using rank 

sums. Technometrics 6, 241-252. 

Dunnett, C.W. (1955). A multiple comparison 

procedure for comparing several treatments with a 

control. J. Am. Stat. Assoc. 50, 1096-1121. 

Durmick, J.K., Elwell, M.R., Benson, J.M., 

Hobbs, C.H., Hahn, F.F., Haley, P.J., Cheng, Y.S., 

and Eidson, A.F. (1989). Lung toxicity after 

13-week inhalation exposure to nickel oxide, nickel 

subsulfide, or nickel sulfate hexahydrate in F344/N 

rats and B6C3F~ mice. Fundam. Appl. Toxicol. 12, 

584-594. 

Eichorn, G.L., and Shin, Y.A. (1968). Interaction 

of metal ions with polynucleotides and related 

compounds: XII. The relative effects of various 

metal ions on DNA helicity. J. Am. Chem. Soc. 90, 

7323-7328. 

English, J.C., Parker, R.D.R., Sharma, R.P., and 

Oberg, S.G. (1981). Toxicokinetics of nickel in rats 

after intratracheal administration of a soluble and 

insoluble form. Am. Ind. Hyg. Assoc. J. 42, 

486-492. 

Enterline, P.E., and Marsh, G.M. (1982). Mortality 

among workers in a nickel refinery and alloy 

manufacturing plant in West Virginia. JNCI 68, 

925-933. 

European Chemical Industry (1989). Nickel and 

Nickel Compounds: Review of Toxicology a~d 

Epidemiology with Special Reference to 

Carcinogenesis. Technical Report No. 33. 

Evans, R.M., Davies, P.J.A., and Costa, M. (1982). 

Video time-lapse microscopy of phagocytosis and 

intracellular fate of crystalline nickel sulfide particles 

.in cultured mammalian cells. Cancer Res. 42, 

2729-2735. 

Farrell, R.L., and Davis, G.W. (1974). The effects 

of particulates on respiratory carcinogenesis by 

diethylnitrosamine. In Experimental Lung Cancer, 

Carcinogenesis and Bioassays (E. Karbe and 

J.F. Park, Eds), pp. 219-233. Springer, New York. 
References 111 

Federal Register (1987). Notice of the first priority 

of hazardous substances that will be the subject of 

toxicological profiles and guidelines for development 

of toxicological profiles. Vol. 52, No. 74. U.S. 

Environmental Protection Agency, Washington, DC. 

Figoni, R.A., and Treagan, L. (1975). Inhibitory 

effect of nickel and chromium upon antibody 

response of rats to immunization with T-1 phage. 

Res. Commun. Chem. Pathol. Pharmacol. 11, 

335-338. 

Finch, G.L., Fisher, G.L., and Hayes, T.L. (1987). 

The pulmonary effects and clearance of 

intratracheally instilled Ni3S 2 and TiO2 in mice. 

Environ. Res. 42, 83-93. 

Fisher, G.L., Chrisp, C.E., and McNeill, D.A. 

(1986).. Lifetime effects of intratracheally instilled 

nickel subsulfide on B6C3Fi mice. Environ. Res. 40, 

313-320. 

Fornace, A.J., Jr. (1982). Detection of DNA singlestrand breaks produced during the repair of damage 

by DNA-protein cross-linking agents. Cancer Res. 

42, 145-149. 

Furst, A., and Schlauder, M.C. (1971). The hamster 

as a model for metal carcinogenesis. Proc. West. 

Pharmacol. Soc. 14, 68-71. 

Gart, J.J., Chu, K.C., and Tarone, R.E. (1979). 

Statistical issues in interpretation of chronic bioassay 

tests for carcinogenicity. J. Natl. Cancer Inst. 62, 

957-974. 

Gilani, S.H., and Marano, M. (1980). Congenital 

abnormalities in nickel poisoning in chick embryos. 

Arch. Environ. Contam. Toxicol. 9, 17-22. 

Gilman, J.P.W. (1962). Metal carcinogenesis: II. A 

study of the carcinogenic activity of cobalt, copper, 

iron, and nickel compounds. Cancer Res. 22, 

158-162. 

Gilman, J.P.W. (1966). Muscle tumourigenesis. 

Can. Cancer Conf 6, 209-223. 

Gilman, J.P.W., and Herchen, H. (1963). The effect 

of physical form of implant on nickel sulphide 

tumourigenesis in the rat. Acta Unio Int. Contra 

Cancrum 19, 617-619. 

Glaser, U., Hochrainer, D., Oldiges, H., and 

Takenake, S. (1986). Long-term inhalation studies 

with NiO and As202 aerosols in Wistar rats. 

Excerpta Med. Int. Congr. Sci. 676, 325-328. 

Glaser, U., Hochrainer, D., Otto, F.J., and 

Oldiges, H. (1990). Carcinogenicity and toxicity of 

four cadmium compounds inhaled by rats. Toxicol. 

Environ. Chem. 27, 153-162. 

Goldberg, M., Goldberg, P., Leclerc, A., 

Chastang, J.-F., Marne, M.-J., and Dubourdieu, D. 

(1994). A 10-year incidence survey of respiratory 

cancer and a case-control study within a cohort of 

nickel mining and refining workers in New 

Caledonia. Cancer Causes Control 5, 15-25. 

Graham, J.A., Gardner, D.E., Miller, F.J., 

Daniels, M.J., and Coffin, D.L. (1975a). Effect of 

nickel chloride on primary antibody production in the 

spleen. Environ. Health Perspect. 12, 109-113. 

Graham, J.A., Gardner, D.E., Waters, M.D., and 

Coffin, D.L. (1975b). Effect of trace metals on 

phagocytosis by alveolar macrophages. Infect. 

Immun. 11, 1278-1283. 

Graham, J.A., Miller, F.J., Daniels, M.J., 

Payne, E.A., and Gardner, D.E. (1978). Influence 

of cadmium, nickel, and chromium on primary 

immunity in mice. Environ. Res. 16, 77-87. 

Grandjean, P. (1984). Human exposure to nickel. 

In Nickel in the Human Environment 

(F.W. Sunderman, Jr., A. Aitio, A. Berlin, 

C. Bishop, E. Buringh, W. Davis, M. Gounar, 

P.C. Jacquignon, E. Mastromatteo, J.P. Rigaut, 

C. Rosenfeld, R. Saracci, and A. Sors, Eds.), IARC 

Scientific Publications No. 53, pp. 469-486. Oxford 

University Press, Oxford. 
112 Nickel Oxide, NTP TR 451 

Groth, D.H., Stealer, L.E., Burg, J.R., 

Busey, W.M., Grant, G.C., and Wong, L. (1986). 

Carcinogenic effects of antimony trfoxide and 

antimony ore concentrate in rats. J. Toxicol. 

Environ. Health 18, 607-626. 

Haley, P.J., Bice, D.E., Muggenburg, B.A., 

Hahn, F.F., and Benjamin, S.A. (1987). 

Immunopathologic effects of nickel subsulfide on the 

primate pulmonary immune system. Toxicol. Appl. 

Pharmacol. 88, 1-12. 

Haley, P.J., Shopp, G.M., Benson, J.M., 

Cheng, Y.-S., Bice, D.E., Luster, M.I., 

Dunnick, J.K., and Hobbs, C.H. (1990). The 

immunotoxicity of three nickel compounds following 

13-week inhalation exposure in the mouse. Fundam. 

Appl. Toxicol. 15, 476-487. 

Haseman, J.K. (1984). Statistical issues in the 

design, analysis and interpretation of animal 

carcinogenicity studies. Environ. Health Perspect. 

58, 385-392. 

Haseman, J.K., Huff, J., and Boorman, G.A. (1984). 

Use of historical control data in carcinogenicity 

studies in rodents. Toxicol. Pathol. 12, 126-135. 

Haseman, J.K., Huff, J.E., Rao, G.N., Arnold, J.E., 

Boorman, G.A., and McConnell, E.E. (1985). 

Neoplasms observed in untreated and corn oil gavage 

control groups of F344/N rats and (C57BL/6N × 

C3H/HeN)F~ (B6C3F~) mice. JNCI 75, 975-984. 

Heinrich, U., Peters, L., Ernst, H., 

Rittinghausen, S., Dasenbrock, C., and K6nig, H. 

(1989). Investigation on the carcinogenic effects of 

various cadmium compounds after inhalation 

exposure .in hamsters and mice. Exp. Pathol. 37, 

253-258. 

Henderson, R.F., and Escobedo, L.G. (1976). 

Effect of repeated halothane anesthesias on Syrian 

hamster lung lipids. Lab. Anim. Sci. 26, 899. 

Henderson, R.F., Benson, J.M., Hahn, F.F., 

Hobbs, C.H., Jones, R.K., Mauderly, J.L., 

McClellan, R.O., and Pickrell, J.A. (1985). New 

approaches for the evaluation of pulmonary toxicity: 

Bronchoalveolar lavage fluid analysis. Fundam. 

Appl. Toxicol. 5, 451-458. 

Hennighausen, G., and Lange, P. (1980). A simple 

technique of testing for the influence of metal salts 

and other chemicals on macrophages and thymocytes 

in vitro. Arch. Toxicol. (Suppl. 4), 143-147. 

Herchen, H., and Gilman, J.P.W. (1964). Effect of 

duration of exposure on nickel sulphide 

tumorigenesis. Nature 202, 306-307. (Abstr.) 

Hildebrand, H.F., and Biserte, G. (1979a). Nickel 

sub-sulphide-induced leiomyosarcoma in rabbit white 

skeletal muscle. A light microscopical and 

ultrastructural study. Cancer 43, 1358-1374. 

Hildebrand, H.F., and Biserte, G. (1979b). 

Cylindrical laminated bodies in nickel-subsulphideinduced rhabdomyosarcoma in rabbits. Eur. J. Cell 

Biol. 19, 276-280. 

Hochrainer, D., Oberdoerster, G., and Mihm, U. 

(1980). Generation of NiO aerosols for studying 

lung clearance of Ni and its effect on lung function. 

In Aerosols in Science, Medicine, and Technology: 

Physical and Chemical Properties of Aerosols, Eighth 

Conference, pp. 259-264. 

Hogetveit, A.C., Barton, R.T., and. Kostol, C.O. 

(1978). Plasma nickel as a primary index of 

exposure in nickel refining. Ann. Occup. Hyg. 21, 

113-120. 

Hollander, M., and Wolfe, D.A. 

Nonparametric Statistical Methods, pp. 

John Wiley and Sons, New York. 

(1973). 

120-123. 

Horie, A., Haratake, J., Tanaka, I., Kodama, Y., 

and Tsuchiya, K. (1985). Electron microscopical 

findings with special reference to cancer in rats 

caused by inhalation of nickel oxide. Biol. Trace 

Elem. Res. 7, 223-239. 
References 113 

Hui, G., and Sunderman, F.W., Jr. (1980). Effects 

of nickel compounds on incorporation of [3H] 

thymidine into DNA in rat liver and kidney. 

Carcinogenesis 1, 297-304. 

Inoue, S., and Kawanishi, S. (1989) ESR evidence 

of superoxide, hydroxyl radicals and singlet oxygen 

produced from hydrogen peroxide and nickel (II) 

complex of glycylglycyl-L-histidine. Biochem. 

Biophys. Res. Commun. 159, 445-451. 

International Agency for Research on Cancer (IARC) 

(1976). IARC Monographs on the Evaluation of the 

Carcinogenic Risk of Chemicals to Man: Cadmium, 

Nickel, Some Epoxides, Miscellaneous Industrial 

Chemicals and General Considerations on Volatile 

Anaesthetics, Vol. 11, pp. 75-112. IARC, Lyon, 

France. 

International Agency for Research on Cancer (IARC) 

(1984). IARC Monographs on the Evaluation of the 

Carcinogenic Risk of Chemicals to Humans: 

Polynuclear Aromatic Compounds, Part 3, Industrial 

Exposures in Aluminum Production, Coal 

Gasification, Coke Production, and Iron and Steel 

Founding, Vol. 34, pp. 133-190. IARC, Lyon, 

France.. 

International Agency for Research on Cancer (IARC) 

(1987). IARC Monographs on the Evaluation of 

Carcinogenic Risks to Humans. Overall Evaluations 

of Carcinogenicity: An Updating of IARC 

Monographs Volumes 1 to 42 (Suppl. 7), 

pp. 264-269. IARC, Lyon, France. 

International Agency for Research on Cancer (IARC) 

(1990). IARC Monographs on the Evaluation of 

Carcinogenic Risks to Humans. Chromium, Nickel 

and Welding, Vol. 49. IARC, Lyon, France. 

Jasmin, G., and Riopelle, J.L. (1976). Renal 

carcinomas and. erythrocytosis in rats following 

intrarenal injection of nickel subsulfide. Lab. Invest. 

35, 71-78. 

Jonckheere, A.R. (1954). A distribution-free 

k-sample test against ordered alternatives. Biometrika 

41, 133-145. 

Judde, J.G., Breillout, F., Clemenceau, C., 

Poupon, M.F., and Jasmin, C. (1987). Inhibition of 

rat natural killer cell function by carcinogenic nickel 

compounds: Preventive action of manganese. JNCI 

78, 1185-1190. 

Kanematsu, N., Hara, M., and Kada, T. (1980). 

Rec assay and mutagenicity studies on metal 

compounds. Mutat. Res. 77, 109-116. 

Kaplan, E.L., and Meier, P. (~-958). Nonparametric 

estimation from incomplete observations. J. Am. 

Stat. Assoc. 53, 457-481. 

Kargacin, B., Klein, C.B., and Costa, M. (1993). 

Mutagenic responses of nickel oxides and nickel 

sulfides in Chinese hamster V79 cell lines at the 

xanthine-guanine phosphoribosyl transferase locus. 

Mutat. Res. 300, 63-72. 

Kasprzak, K.S., Gabryel, P., and Jarczewska, K. 

(1983). Carcinogenicity of nickel(II)hydroxides and 

nickel(II)sulfate in Wistar rats and its relation to the 

in vitro dissolution rates. Carcinogenesis 4, 275-279. 

Keith, L.H., Crummett, W., Degan, J., Jr., 

Libby, R.A., Taylor, J.K., and Wentler, G. (1983). 

Principles of environmental analysis. Anal. Chem. 

55, 2210-2218. 

Kirk-Othmer Encyclopedia of Chemical Technology 

(1978). 3rd ed., Vol. 15, p. 801. John Wiley and 

Sons, New York. 

Klein, C.B., Conway, K., Wang, X.W., 

Bhamra, R.K., Lin, X., Cohen, M.D., Annab, L., 

Barrett, J.C., and Costa, M. (1991). Senescence of 

nickel-transformed cells by an X chromosome: 

Possible epigenetic control. Science 251, 796-799. 

Kodama, Y., Ishimatsu, S., Matsuno, K., Tanaka, I., 

and Tsuchiya, K. (1985). Pulmonary deposition and 

clearance of a nickel oxide aerosol by inhalation. 

Biol. Trace Elem. Res. 7, 1-9. 

Larkins, F.P. (1967). Decomposition of nickel 

oxide. Nature 215, 1268. 
114 Nickel Oxide, NTP TR 451 

Larramendy, M.L., Popescu, N.C., and 

DiPaolo, J.A. (1981). Induction by inorganic metal 

salts of sister chromatid exchanges and chromosome 

aberrations in human and Syrian hamster cell strains. 

Environ. Mutagen. 3, 597-606. 

Lau, T.J., Hackett, R.L., and Sunderman, F.W.., Jr. 

(1972). The carcinogenicity of intravenous nickel 

carbonyl in rats. Cancer Res. 32, 2253-2258. 

Lawrence, D.A. (1981). Heavy metal modulation of 

lymphocyte activities. I. In vitro effects of heavy 

metals on primary humoral immune responses. 

Toxicol. Appl. Pharmacol. 57, 439-451. 

Lee, J.E., Ciccarelli, R.B., and Jennette, K.W. 

(1982). Solubilization of the carcinogen nickel 

subsulfide and its interaction with deoxyribonucleic 

acid and protein. Biochemistry 21, 771-778. 

Lee, K.P., Trochimowicz, H.J., and Reinhardt, C.F. 

(1985). Pulmonary response of rats exposed to 

titanium dioxide (TiO2) by inhalation for two years. 

Toxicol. Appl. Pharmacol. 79, 179-192. 

Lee, K.P., Ulrich, C.E., Geil, R.G., and 

Trochimowicz, H.J. (1988). Effects of inhaled 

chromium dioxide dust on rats exposed for two 

years. Fundam. Appl. Toxicol. 10, 125-145. 

Lee, Y.W., Pons, C., Tummolo, D.M., Klein, C.B., 

Rossman, T.G., and Christie, N.T. (1993). 

Mutagenicity of soluble and insoluble nickel 

compounds at the gpt locus in G12 Chinese hamster 

cells. Environ. Mol. Mutagen. 21, 365-371. 

Leonard, A., and Jacquet, P. (1984). 

Embryotoxicity and genotoxicity of nickel. In Nickel 

in the Human Environment (F.W. Sunderman, Jr., 

A. Aitio, A. Berlin, C. Bishop, E. Buringh, 

W. Davis, M. Gounar, P.C. Jacquignon, 

E. Mastromatteo, J.P. Rigaut, C. Rosenfeld, 

R. Saracci, and A. Sors, Eds.), IARC Scientific 

Publications No. 53, pp. 277-292. Oxford 

University Press, Oxford. 

Littlefield, N.A., Fullerton, F.R., and Poirier, L.A. 

(1991). Hydroxylation and deglycosylation of 

2'-deoxyguanosine in the presence of magnesium and 

nickel. Chem. Biol. Interact. 79, 217-228. 

McConnell, E.E., Solleveld, H.A., Swenberg, J.A., 

and Boorman, G.A. (1986). Guidelines for 

combining neoplasms for evaluation of rodent 

carcinogenesis studies. JNCI 76, 283-289. 

McGregor, D.B., Brown, A., Cattanach, P., 

Edwards, I., McBride, D., Riach, C., and 

Caspary, W.J. (1988). Responses of the L5178Y 

tk÷/tk - mouse lymphoma cell forward mutation 

assay: III. 72 coded chemicals. Environ. Mol. 

Mutagen. 12, 85-154. 

MacGregor, J.T., Wehr, C.M., and Langlois, R.G. 

(1983). A simple fluorescent staining procedure for 

micronuclei and RNA in erythrocytes using Hoescht 

33258 and pyronin Y. Mutat. Res. 120, 269-275. 

MacGregor, J.T., Wehr, C.M., Henika, P.R., and 

Shelby, M.D. (1990). The in vivo erythrocyte 

micronucleus test: Measurement at steady state 

increases assay efficiency and permits integration 

with toxicity studies. Fundam. Appl. Toxicol 14, 

513-522. 

Mcllveen, W.D., and Negusanti, J.J. (1994). Nickel 

in the terrestrial environment. Sci. Total Environ. 

148, 109-138. 

McKnight, B., and Crowley, J. (1984). Tests for 

differences in tumor incidence based on animal 

carcinogenesis experiments. J. Am. Stat. Assoc. 79, 

639-648. 

Margolin, B.H., Risko, K.J., Frome, E.L., and 

Tice, R.R. (1990). A General Purpose Statistical 

Analysis Program for Micronucleus Assay Data. 

Appendix 2: Micronucleus Assay Data Management 

and Analysis System, Version 1.4a. Integrated 

Laboratory Systems, Research Triangle Park, NC. 

Maronpot, R.R., and Boorman, G.A. (1982). 

Interpretation of rodent hepatocellular proliferative 

alterations and hepatocellular tumors in chemical 

safety assessment. Toxicol. Pathol. 10, 71-80. 

Mas, A., Holt, D., and Webb, M. (1985). The acute 

toxicity and teratogenicity of nickel in pregnant rats. 

Toxicology 35, 47-57. 
References 115 

Mason, M.M. (1972). Nickel sulfide carcinogenesis. 

Environ. Physiol. Biochem. 2, 137-141. 

Mathur, A.K., Dikshith, T.S.S., Lal, M.M., and 

Tandon, S.K. (1978). Distribution of nickel and 

cytogenetic changes in poisoned rats. Toxicology 10, 

105-113, 

Mauderly, J.L, Jones, R.K., Griffith, W.C., 

Henderson, R.F., and McClellan, R.O. (1987). 

Diesel exhaust is a pulmonary carcinogen in rats 

expposed chronically by inhalation. Fundam. Appl. 

Toxicol. 9, 208-221. 

Mauderly, J.L. (1994). Toxicological and 

epidemiological evidence for health risks from 

inhaled engine emissions. Environ. Health Perspect. 

102 (Suppl. 4), 165-171. 

Meedinsky, M.A., Benson, J.M., and Hobbs C.H. 

(1987). Lung clearance and disposition of 63Ni in 

F344/N rats after intratracheal instillation of nickel 

sulfate solutions. Environ. Res. 43, 168-178. 

The Merck Index (1989). llth ed. (S. Budavari, 

Ed.), p. 1028. Merck and Company, Rahway, NJ. 

Migally, N., Murthy, R.C., Doye, A., and 

Zambernard, J. (1982). Changes in pulmonary 

alveolar macrophages in rats exposed to oxides of 

zinc and nickel. J. Submicrosc. Cytol. 14, 621-626. 

Miller, J.A., and Miller, E.C. (1977). Ultimate 

chemical carcinogens as reactive mutagenic 

electrophiles. In Origins of Human Cancer 

(H.H. Hiatt, J.D. Watson, and J.A. Winsten, Eds.), 

pp. 605-627. Cold Spring Harbor Laboratory, Cold 

Spring Harbor, NY. 

Miura, T., Patierno, S.R., Sakuramoto, T., and 

Landolph, J.R. (1989). Morphological and 

neoplastic transformation of C3H/10T 1/2 CI 8 mouse 

embryo cells by insoluble carcinogenic nickel 

compounds. Environ. Mol. Mutagen. 14, 65-78. 

Morgan, J.G. (1958). Some observations on the 

incidence of respiratory cancer in nickel workers. 

Br. J. Ind. Med. 15, 224-234. 

Morgan, L.G., and Rouge, P.J.C. (1983). Biological 

monitoring in nickel refinery workers. In Nickel in 

the Human Environment (F.W. Sunderman, Jr., 

A. Aitio, A. Berlin, C. Bishop, E. Buringh, 

W. Davis, M. Gounar, P.C. Jacquignon, 

E. Mastromatteo, J.P. Rigaut, C. Rosenfeld, 

R. Saracci, and A. Sors, Eds.), IARC Scientific 

Publications No. 53, pp. 507-520. Oxford 

University Press, Oxford. 

Morita, H., Umeda, M., and Ogawa, H.I. (1991). 

Mutagenicity of various chemicals including nickel 

and cobalt compounds in cultured mouse FM3A 

cells. Mutat. Res. 261, 131-137. 

Morrison, D.F. (1976). Multivariate Statistical 

Methods, 2nd ed., pp. 170-179. McGraw-Hill Book 

Company, New York. 

Muhle, H., Bellmann, B., Takenaka, S., Fuhst, R., 

Mohr, U., and Pott, F. (1992). Chronic effects of 

intratracheally instilled nickel-containing particles in 

hamsters. In Nickel and Human Health: Current 

Perspectives (E. Nieboer and J.O. Nriagu, Eds.), 

pp. 467-479. John Wiley and Sons, Inc., New York. 

Muir, D.C.F., Julian, F., Jadon, N., Roberts, R., 

Roos, J., Chan, J., Maehle, W., and 

Morgan, W.K.C. (1993). Prevalence of small 

opacities in chest radiographs of nickel sinter plant 

workers (1993). Br. J. Indust. Med. 50, 428-431. 

Muir, D.C.F., Jadon, N., Julian, J.A., and 

Roberts, R.S. (1994). Cancer of the respiratory tract 

in nickel sinter plant workers: Effect of removal 

from sinter plant exposure. Occup. Environ. Med. 

51, 19-22. 

Murthy, R.C., and Niklowitz, W.J. (1983). 

Ultrastructural changes in alveolar macrophages of 

rats exposed to nickel oxide by inhalation. J. 

Submicrosc. Cytol. 15, 655-660. 

National Academy of Sciences (NAS) (1975). 

Medical and Biological Effects of Environmental 

Pollutants, Nickel. Washington, DC. 
116 Nickel Oxide, NTP TR 451 

National Cancer Institute (NCI) (1976). Guidelines 

for Carcinogen Bioassay in Small Rodents. 

Technical Report Series No. 1. NIH Publication 

No. 76-801. U.S. Department of Health, Education, 

and Welfare, Public Health Service, National 

Institutes of Health, Bethesda, MD. 

National Cancer Institute (NCI) (1978a). Bioassay of 

1,2-Dibromoethane for Possible Carcinogenicity 

(CAS No. 106-93-4). Technical Report Series 

No. 86. NIH Publication No. 78-1336. U.S. 

Department of Health, Education, and Welfare, 

Public Health Service, National Institutes of Health, 

Bethesda, MD. 

National Cancer Institute (NCI) (1978b). Bioassay of 

1,2-Dichloroethane for Possible Carcinogenicity 

(CAS No. 107-06-2). Technical Report Series 

No. 55. NIH Publication No. 78-1361. U.S. 

Department of Health, Education, and Welfare, 

Public Health Service, National Institutes of Health, 

Bethesda, MD. 

National Cancer Institute (NCI) (1978c). Bioassay of 

Tris (2,3-Dibromopropyl) Phosphate for Possible 

Carcinogenicity. Technical Report Series No. 76. 

NIH Publication No. 78-1326. U.S. Department of 

Health, Education, and Welfare, Public Health 

Service, National Institutes of Health, Bethesda, MD. 

National Cancer Institute (NCI) (1982). Bioassay of 

Reserpine for Possible Carcinogenicity (CAS 

No. 50-55-5). Technical Report Series No. 193. 

NIH Publication NO. 80-1749. U.S. Department of 

Health and Human Services, Public Health Service, 

National Institutes of Health, Bethesda, MD, and 

Research Triangle Park, NC. 

National Institute for Occupational Safety and Health 

(NIOSH) (1977). Criteria for a Recommended 

Standard: Occupational Exposure to Inorganic 

Nickel. Department of Health, Education, and 

Welfare Publication No. 77-164. 

National Institute for Occupational Safety and Health 

(NIOSH) (1991). National Occupational Exposure 

Survey (I 98 i- 1983), unpublished provisional data as 

of January 1, 1991. Cincinnati, OH. 

National Institutes of Health (NIH) (1978). Open 

Formula Mouse and Rat Ration (NIH-07). 

Specifications NIH-11-1335. U.S. Department of 

Health, Education, and Welfare, Public Health 

Service, National Institutes of Health, Bethesda, MD. 

National Toxicology Program (NTP) (1982a). 

Carcinogenesis Bioassay of 1,2-Dibromo-3- 

chloropropane (CAS No. 96-12-8) in F344 Rats and 

B6C3F~ Mice (Inhalation Study). Technical Report 

Series No. 206. NIH Publication No. 82-1762~ 

U.S. Department of Health and Human Services, 

Public Health Service, National Institutes of Health, 

Research Triangle Park, NC, and Bethesda, MD. 

National Toxicology Program (NTP) (1982b). 

Carcinogenesis Bioassay of 1,2-Dibromoethane (CAS 

No. 106-93-4) in F344 Rats and B6C3F~ Mice 

(Inhalation Study). Technical Report Series No. 210. 

NIH Publication No. 82-1766. U.S. Department of 

Health and Human Services, Public Health Service, 

National Institutes of Health, Research Triangle Park, 

NC, and Bethesda, MD. 

National Toxicology Program (NTP) (1986). 

Toxicology and Carcinogenesis Studies of Benzene 

(CAS No. 71-43-2) in F344/N Rats and B6C3F~ 

Mice (Gavage Studies). Technical Report Series 

No. 289. NIH Publication No. 86-2545. U.S. 

Department of Health and Human Services, Public 

Health Service, National Institutes of Health, 

Research Triangle Park, NC. 

National Toxicology Program (NTP) (1988). 

Toxicology and Carcinogenesis Studies of 

2-Mercaptobenzothiazole (CAS No. 149-30-4) in 

F344/N Rats and B6C3Ft Mice (Garage Studies). 

Technical Report Series No. 332. NIH Publication 

No. 88-2588. U.S. Department of Health and 

Human Services, Public Health Service, National 

Institutes of Health, Research Triangle Park, NC. 

National Toxicology Program (NTP) (1990a). 

Toxicology and Carcinogenesis Studies of Glycidol 

(CAS No. 556-52-5) in F344/N Rats and B6C3F~ 

Mice (Gavage Studies). Technical Report Series 

No. 374. NIH Publication No. 90-2829. U.S. 

Department of Health and Human Services, Public 

Health Service, National Institutes of Health, 

Research Triangle Park, NC. 
References 117 

National Toxicology Program (NTP) (1990b). 

Toxicology and Carcinogenesis Studies of 

Bromoethane (Ethyl Bromide) (CAS No. 74-96-4) in 

F344/N Rats and B6C3F~ Mice (Inhalation Studies). 

Technical Report Series No. 363. NIH Publication 

No. 90-2818. U.S. Department of Health and 

Human Services, Public Health Service, National 

Institutes of Health, Research Triangle Park, NC. 

National Toxicology Program (NTP) (1993a). 

Toxicology and Carcinogenesis Studies of Talc (CAS 

No. 14807-96-6) in F344/N Rats and B6C3F~ Mice 

(Inhalation Studies). Technical Report Series 

No. 421. NIH Publication No. 93-3152. U.S. 

Department of Health and Human Services, Public 

Health Service, National Institutes of Health, 

Research Triangle Park, NC. 

National Toxicology Program (NTP) (1993b). 

Toxicology and Carcinogenesis Studies of Coumarin 

(CAS No. 91-64-5) in F344/N Rats and B6C3F~ 

Mice (Gavage Studies). Technical Report Series 

No. 422. NIH Publication No. 93-3153. U.S. 

Department of Health and Human Services, Public 

Health. Service, National Institutes of Health, 

Research Triangle Park, NC. 

National Toxicology Program (NTP) (1994). 

Toxicology and Carcinogenesis Studies of 

2,3-Dibromo-l-propanol (CAS No. 96-13-9) in 

F344/N Rats and B6C3F~ Mice (Dermal Studies). 

Technical Report Series No. 400. NIH Publication 

No. 94-2855. U.S. Department of Health and 

Human Services, Public Health Service, National 

Institutes of Health, Research Triangle Park, NC. 

National Toxicology Program (NTP) (1995). 

Technical Report on the Toxicity Studies of 

Cadmium Oxide (CAS No. 1306-19-0) Administered 

by Inhalation to F344/N Rats and B6C3F~ Mice. 

Toxicity Report Series No. 39. U.S. Department of 

Health and Human Services, Public Health Service, 

National Institutes of Health, Research Triangle Park, 

NC. 

National Toxicology Program (NTP) (1996a). 

Technical Report on the Toxicology and 

Carcinogenesis Studies of Nickel Subsulfide 

(CAS No. 12035-72-2) in F344/N Rats and B6C3Fi 

Mice (Inhalation Studies). Technical Report Series 

Number 453. NIH Publication No. 96-3369. U.S. 

Department of Health and Human Services, Public 

Health Service, National Institutes of Health, 

Research Triangle Park, NC. 

National Toxicology Prograr~t (NTP) (1996b). 

Technical Report on the Toxicology and 

Carcinogenesis Studies of Nickel Sulfate Hexahydrate 

(CAS No. 10101-97-0) in F344/N Rats and B6C3F~ 

Mice (Inhalation Studies). Technical Report Series 

Number 454. NIH Publication No. 96-3370. U.S. 

Department of Health and Human Services, Public 

Health Service, National Institutes of Health, 

Research Triangle Park, NC. 

National Toxicology Program (NTP) (1996c). 

Technical Report on the Toxicology and 

Carcinogenesis Studies of 2,2-Bis(bromomethyl)- 1,3- 

propanediol (CAS No. 3296-90-0) in F344/N Rats 

and B6C3F~ Mice (Feed Studies). Technical Report 

Series Number 452. NIH Publication No. 96-3368. 

U.S. Department of Health and Human Services, 

Public Health Service, National Institutes of Health, 

Research Triangle Park, NC. 

Nemery, B. (1990). Metal toxicity and the 

respiratory tract. Eur. Respir. J. 3, 202-219. 

Nicklin, S., and Nielsen, G.D. (1992). Nickel and 

the immune system: Current concepts. In Nickel and 

Human Health: Current Perspectives (E. Nieboer 

and J.O. Nriagu, Eds.), pp. 239-259. John Wiley 

and Sons, Inc., New York. 

Nieboer, E., and Nriagu, J.O., Eds. (1992). Nickel 

and Human Health: Current Perspectives. 

John Wiley and Sons, Inc., New York. 

Nieboer, E., and Templeton, D.M., Eds. (1994). 

Special Issue: Nickel biochemistry, toxicology, and 

ecological issues Sci. Total Environ. 148. 
118 Nickel Oxide, NTP TR 451 

Nieboer, E., Tom, R.T., and Rossetto, F.E. (1989). 

Superoxide dismutase activity and novel reactions 

with hydrogen peroxide of histidine-containing 

nickel(II)-oligopeptide complexes and nickel(II)- 

induced structural changes in synthetic DNA. Biol. 

Trace Element Res. 21, 23-33. 

Nielsen, G.D., Andersen, O., and Jensen, M. 

(1993). Toxicokinetics of nickel in mice studied with 

the 3,-emitting isotope 57Ni. Fundam. Appl. Toxicol. 

21, 236-243. 

Nishimura, M., and Umeda, M. (1979). Induction 

of chromosomal aberrations in cultured mammalian 

cells by nickel compounds. Mutat. Res. 68, 337-349. 

Norseth, T. (1994). Environmental pollution around 

nickel smelters in the Kola Peninsula (Russia). Sci, 

Total Environ. 148, 103-108. 

Ohno, H., Hanaoka, F., and Yamada, M. (1982). 

Inducibility of sister-chromatid exchanges by heavymetal ions. Mutat. Res. 104, 141-145. 

Okamoto, M. (1987). Induction of ocular tumor by 

nickel subsulfide in the Japanese common newt, 

Cynops pyrrhogaster. Cancer Res. 47, 5213-5217. 

Olsen, I., and Jonsen, J. (1979). Whole-body 

autoradiography of 63Ni in mice throughout gestation. 

Toxicology 12, 165-172. 

Oskarsson, A., Andersson, Y., and Tj~ilve, H. 

(1979). Fate of nickel subsulfide during 

carcinogenesis studied by autoradiography and X-ray 

powder diffraction. Cancer Res. 39, 4175=4182. 

Ottolenghi, A.D., Haseman, J.K., Payne, W.W., 

Falk, H.L., and MacFarland, H.N. (1975).. 

Inhalation studies of nickel sulfide in pulmonary 

carcinogenesis of rats. J. Natl. Cancer Inst. 54, 

1165-1170. 

Patierno, S.R., and Costa, M. (1985). DNA-protein 

cross-links induced by nickel compounds in intact 

cultured mammalian cells. Chem. Biol. Interact. 55, 

75-91. 

Paton, G.R., and Allison, A.C. (1972). 

Chromosome damage in human cell cultures induced 

by metal salts. Mutat. Res. 16, 332-336. 

Payne, W.W. (1964). Carcinogenicity of nickel 

compounds in experimental animals. Proc. Am. 

Assoc. Cancer Res. 5, 50. (Abstr.) 

Peto, J., Cuckle, H., Doll, R., Hermon, C., and 

Morgan, L.G. (1984). Respiratory cancer mortality 

of Welsh nickel refinery workers. In Nickel in the 

Human Environment (F.W. Sunderman, Jr., A. Aitio, 

A. Berlin, C. Bishop, E. Buringh, W. Davis, 

M. Gounar, P.C. Jacquignon, E. Mastromatteo, 

J.P. Rigaut, C. Rosenfeld, R. Saracci, and A. Sors, 

Eds.), IARC Scientific Publications No. 53, 

pp. 37-46. Oxford University Press, Oxford. 

Poirier, L.A., Theiss, J.C., Arnold, L.J., and 

Shimkin, M.B. (1984). Inhibition by magnesium and 

calcium acetates of lead subacetate- and nickel 

acetate-induced lung tumors in strain A mice. 

Cancer Res. 44, 1520-1522. 

Popp, W., Vahrenholz, C., Goch, S., Miiller, C., 

Miiller, G., Schmieding, W., and Norpoth, K. 

(1992). Experiences with alkaline filter elution for 

the detection of DNA damage by genotoxic 

compounds. Zbl. Hyg. 3, 140-149. 

Pott, F., Ziem, U., Reiffer, F.-J., Huth, F., 

Ernst, H., and Mohr, U. (1987). Carcinogenicity 

studies on fibres, metal compounds, and some other 

dusts in rats. Exp. Pathol. 32, 129-152. 

Pott, F., Rippe, R.M., Roller, M., Csicsaky, M., 

Rosenbruch, M., and Huth, F. (1989). Tumours in 

the abdominal cavity of rats after intraperitoneal 

injection of nickel compounds. In International 

Conference on Heavy Metals in the Environment 

(J.-P. Vernet, Ed.), Vol. 2, pp. 127-129. CEP 

Consultants, Edinburgh. 
Re~rences 119 

Pott, F., Rippe, R.M., Roller, M., Csicsaky, M., 

Rosenbruch, M., and Huth, F. (1992). 

Carcinogenicity of nickel compounds and nickel 

alloys in rats by intraperitoneal injection. In Nickel 

and Human Health: Current Perspectives 

(E. Nieboer and J.O. Nriagu, Eds.), pp. 491-502. 

John Wiley and Sons, Inc., New York. 

Registry of Toxic Effects of Chemical Substances 

(RTECS) (1987). Vol. 3A (D.V. Sweet, Ed.). U.S. 

Department of Health and Human Services, Public 

Health Service, Centers for Disease Control, 

National Institute for Occupational Safety and Health. 

Rhoda, R.N., Antonsen, D.H., and Hill, B. (1981). 

Characterization of INCO nickel oxide. Ind. Eng. 

Chem. -- Product Research Development 20, 378. 

Roberts, R.S., Julian, J.A., Sweezey, D., 

Muir, D.C.F., Shannon, H.S., and Mastromatteo, E. 

(1989a). A study of mortality in workers engaged in 

the mining, smelting, and refining of nickel: I. 

Methodology and mortality by major cause groups. 

Toxicol. Ind. Health 5, 957-974. 

Roberts, R.S., Julian, J.A., Muir, D.C.F., and 

Shannon, H.S. (1989b). A study of mortality in 

workers engaged in the mining, smelting, and 

refining of nickel: II. Mortality from cancer of the 

respiratory tract and kidney. Toxicol. Ind. Health 5, 

975 -993. 

Robison, S.H., Cantoni, O., and Costa, M. (1982). 

Strand breakage and decreased molecular weight of 

DNA induced by specific metal compounds. 

Carcinogenesis 3, 657-662. 

Robison, S.H., Cantoni, O., Heck, J.D., and 

Costa, M. (1983). Soluble and insoluble nickel 

compounds induce DNA repair synthesis in cultured 

mammalian cells. Cancer Lett. 17, 273-279. 

Rodriguez-Arnaiz, R., and Ramos, P.M. (1986). 

Mutagenicity of nickel sulphate in Drosophila 

melanogaster. Mutat. Res. 170, 115-117. 

Rossetto, F.E., Turnbull, J.D., and Nieboer, E. 

(1994). Characterization of nickel-induced 

mutations. Sci. Total Environ. 148, 201-206. 

Saxholm, H.J.K., Reith, A., and Brogger, A. (1981). 

Oncogenic transformation and cell lysis in 

C3H/10T~A cells and increased sister chromatid 

exchange in human lymphocytes by nickel subsulfide. 

Cancer Res. 41, 4136-4139. 

Schmid, W. (1976). The micrbnucleus test for 

cytogenetic analysis. In Chemical Mutagens: 

Principles and Methods for their Detection 

(A. Hollaender, Ed.), Vol. 4, pp. 31-53. Plenum 

Press, New York. 

Schroeder, H.A., and Mitchener, M. (1975). Lifeterm effects of mercury, methyl mercury, and nine 

other trace metals on mice. J. Nutr. 105, 452-458. 

Schroeder, H.A., Balassa, J.J., and Vinton, W.H., 

Jr. (1964). Chromium, lead, cadmium, nickel, and 

titanium in mice: Effect on mortality, tumors and 

tissue levels. J. Nutr. 83, 239-250. 

Sen, P., and Costa, M. (1986a). Pathway of nickel 

uptake influences its interaction with heterochromatic 

DNA. Toxicol. Appl. Pharmacol. 84, 278-285. 

Sen, P., and Costa, M. (1986b). Incidence and 

localization of sister chromatid exchanges induced by 

nickel and chromium compounds. Carcinogenesis 7, 

1527-1533. 

Sen, P., Conway, K., and Costa, M. (1987). 

Comparison of the localization of chromosome 

damage induced by calcium chromate and nickel 

compounds. Cancer Res. 47, 2142-2147. 

Shi, X., Dalai, N.S., and Kasprzak, K.S. (1993). 

Generation of free radicals in reactions of Ni(II)-thiol 

complexes with molecular oxygen and model lipid 

hydroperoxides. J. Inorg. Biochem. 15, 211-225. 

Shibata, M., Izumi, K., Sano, N., Akagi, A., and 

Otsuka, H. (1989). Induction of soft tissue tumours 

in F344 rats by subcutaneous, intramuscular, intraarticular, and retroperitoneal injection of nickel 

sulphide (Ni3S:). J. Pathol. 157, 263-274. 

Shirley, E. (1977). A non-parametric equivalent of 

Williams' test for contrasting increasing dose levels 

of a treatment. Biometrics 33, 386-389. 
120 Nickel Oxide, NTP TR 451 

Skaug, V., Gylseth, B., Reiss, A.-L.P., and 

Norseth, T. (1985). Tumor induction in rats after 

intrapleural injection of nickel subsulphide and nickel 

oxide. In Progress in Nickel Technology 

(S.S. Brown and F.W. Sunderman, Jr., Eds.), 

pp. 37-40. Blackwell Scientific Publications, Oxford. 

Smialowicz, R.J., Rogers, R.R., Riddle, M.M., and 

Stott, G.A. (1984). Immunologic effects of nickel: 

I. Suppression of cellular and humoral immunity. 

Environ. Res. 33, 413-427. 

Smialowicz, R.J., Rogers, R.R., Riddle, M.M., 

Garner, R.J., Rowe, D.G., and Luebke, R.W. 

(1985). Immunologic effects of nickel: II. 

Suppression of natural killer cell activity. Environ. 

Res. 36, 56-66. 

Smialowicz, R.J., Rogers, R.R., Riddle, M.M., 

Rowe, D.G., and Luebke, R.W. (1986). 

Immunological studies in mice following in utero 

exposure to NiCI 2. Toxicology 38, 293-303. 

Smith, M.K., George, E.L., Stober, J.A., 

Feng, H.A., and Kimmel, G.L. (1993). Perinatal 

toxicity associated with nickel chloride exposure. 

Environ. Res. 61, 200-211. 

Smith-Sonneborn, J., Leibovitz, B., Donathan, R., 

and Fisher, G.L. (1986). Bioassay of environmental 

nickel dusts in a particle feeding ciliate. Environ. 

Mutagen. 8, 621-626. 

Snow, E.T. (1992). Metal carcinogenesis: 

Mechanistic implications. Pharmacol. Ther. 53, 

31-65. 

Sosifiski, E. (1975). Morphological changes in rat 

brain and skeletal muscle in the region of nickel 

oxide implantation. Neuropatol. Pol. 13, 479-483. 

Spiegelberg, T., K/Srdel, W., and Hochrainer, D. 

(1984). Effects of NiO inhalation on alveolar 

macrophages and the humoral immune systems of 

rats. Ecotoxicol. Environ. Safety 8, 516-525. 

Stoner, G.D., Shimkin, M.B., Troxell, M.C., 

Thompson, T.L., and Terry, L.S. (1976). Test for 

carcinogenicity of metallic compounds by the 

pulmonary tumor response in strain A mice. Cancer 

Res. 36, 1744-1747. 

Straus, D.S. (1981). Somatic mutation, cellular 

differentiation, and cancer causation. JNCI 67, 

233-241. 

Sugiyama, M. (1994). Role of cellular antioxidants 

in metal-induced damage. Cell Biol. Toxicol. 10, 

1-22. 

Sunderman, F.W., Jr. (1981). Recent research on 

nickel carcinogenesis. Environ. Health Perspect. 40, 

131-141. 

Sunderman, F.W., Jr. (1983a). Organ and species 

specificity in nickel subsulfide carcinogenesis. In 

Organ and Species Specificity in Chemical 

Carcinogenesis (R. Langenbach, S. Nesnow, and 

J.M. Rice, Eds.), pp. 107-126. Plenum Press, New 

York. 

Sunderman, F.W., Jr. (1983b). Potential toxicity 

from nickel contamination of intravenous fluids. 

Ann. Clin. Lab. Sci. 3, 1-4. 

Sunderman, F.W., Jr. (1984). Carcinogenicity of 

nickel compounds in animals. In Nickel in the 

Human Environment (F.W. Sunderman, Jr., A. Aitio, 

A. Berlin, C. Bishop, E. Buringh, W. Davis, 

M. Gounar, P.C. Jacquignon, E. Mastromatteo, 

J.P. Rigaut, C. Rosenfeld, R. Saracci, and A. Sors, 

Eds.), IARC Scientific Publications No. 53, 

pp. 127-142. Oxford University Press, Oxford. 

Sunderman, F.W., Jr. (1989). Mechanistic aspects 

of nickel carcinogenicity. Arch. Toxicol. (Suppl. 13), 

40-47. 

Sunderman, F.W., Jr. (1992). Toxicokinetics of 

nickel in humans. In Nickel and Human Health: 

Current Perspectives (E. Nieboer and J.O. Nriagu, 

Eds.), pp. 69-76. John Wiley and Sons, Inc., New 

York. 
References 121 

Sunderman, F.W., and Donnelly, A.J. (1965). 

Studies of nickel carcinogenesis. Metastasizing 

pulmonary tumors in rats induced by the inhalation of 

nickel carbonyl. Am. J. Clin. Pathol. 46, 

1027-1041. 

Sunderman, F.W., Jr., Shen, S.K., Reid, M.C., and 

Allpass, P.R. (1980). Teratogenicity and 

embryotoxicity of nickel carbonyl in Syrian hamsters. 

Teratog. Carcinog. Mutagen. 1, 223-233. 

Sunderman, F.W., Jr., McCully, K.S., and 

Sunderman, F.W., Jr., and McCully, K.S. (1983). Rinehimer, L.A. (1981). Negative test for 

Carcinogenesis tests of nickel arsenides, nickel transplacental carcinogenicity of nickel subsulfide in 

antimonide, and nickel telluride in rats. Cancer Fischer rats. Res. Commun. Chem. Pathol. 

Invest. 1~ 469-474. Pharmacol. 31, 545-554. 

Sunderman, F.W., Jr., and Maenza, R.M. (1976). 

Comparisons of carcinogenicities of nickel 

compounds in rats. Res. Commun. Chem. Pathol. 

Pharmacol. 14, 319-330. 

Sunderman, F.W., and Oskarsson, A. (1991). 

Nickel. In Metals and Their Compounds in the 

Environment (E. Merian, Ed.), pp. 1101-1126. VCH 

Verlagsgesellschaft, New York. 

Sunderman, F.W., Kincaid, J.F., Donnelly, A.J., 

and West, B. (1957). Nickel poisoning. IV. 

Chronic exposure of rats to nickel carbonyl: A 

report after one year observation. Arch. Environ. 

Health 16, 480-485. 

Sunderman, F.W., Donnelly, A.J., West, B., and 

Kincaid, J.F. (1959). Nickel poisoning: IX. 

Carcinogenesis in rats exposed to nickel carbonyl. 

A.M.A. Arch. Ind. Health 20, 36-41. 

Sunderman, F.W., Jr., Kasprzak, K.S., Lau, T.J., 

Minghetti, P.P., Maenza, R.M., Becker, N., 

Onkelinx, C., and Goldblatt, P.J. (1976). Effects of 

manganese on carcinogenicity and metabolism of 

nickel subsulfide. Cancer Res. 36, 1790-1800. 

Sunderman, F.W., Jr., Shen, S.K., Mitchell, J.M., 

Allpass, P.R., and Damjanov, I. (1978). 

Embryotoxicity and fetal toxicity of nickel in rats. 

Toxicol. Appl. Pharmacol. 43, 381-390. 

Sunderman, F.W., Jr., Maenza, R.M., 

Hopfer, S.M., Mitchell, J.M., Allpass, P.R., and 

Damjanov, I. (1979). Induction of renal cancers in 

rats by intrarenal injection of nickel subsulfide. J. 

Environ. Pathol. Toxicol. 2, 1511-1527. 

Sunderman, F.W., Jr., Reid, M.C., Shen, S.K., and 

Kevorkian, C.B. (1983). Embryotoxicity and 

teratogenicity of nickel compounds. In Reproductive 

and Developmental Toxicity of Metals 

(T.W. Clarkson, G.F. Nordberg, and P.R. Sager, 

Eds.), pp. 399-416. Plenum Press, New York. 

Sunderman, F.W., Jr., McCully, K.S., and 

Hopfer, S.M. (1984). Association between 

erythrocytosis and renal cancers in rats following 

intrarenal injection of nickel compounds. 

Carcinogenesis 5, 1511-1517. 

Sunderman, F.W., Jr., Hopfer, S.M., Knight, J.A., 

McCully, K.S., C6cutti, A.G., Thornhill, P.G., 

Conway, K., Miller, C., Patierno, S.R., and 

Costa, M. (1987). Physiochemical characteristics 

and biological effects of nickel oxides. 

Carcinogenesis 8, 305-313. 

Sunderman, F.W., Jr., Morgan, L.G., Andersen, A., 

Ashley, D., and Forouhar, F.A. (1989). 

Histopathology of sinonasal and lung cancers in 

nickel refinery workers. Ann. Clin. Lab. Sci. 19, 

44-50. 

Takenaka, S., Glaser, U., Oldiges, H., and 

Mohr, U. (1990). Morphological effects of CDOaerosols on the rat lung. Toxicol. Environ. Chem. 

• 27, 163-172. 

Tanaka, I., Ishimatsu, S., Matsuno, K., Kodama, Y., 

and Tsuchiya, K. (1985). Biological half time of 

deposited nickel oxide aerosol in rat lung by 

inhalation. Biol. Trace Elem. Res. 8, 203-210. 
122 Nickel Oxide, NTP TR 451 

Tanaka, I., Horie, A., Haratake, J., Kodama, Y., 

and Tsuchiya, K. (1988). Lung burden of green 

nickel oxide aerosol and histopathological findings in 

rats after continuous inhalation. Biol. Trace Elem. 

Res. 16, 1986. 

Tarone, R.E. (1975). Tests for trend in life table 

analysis. Biometrika 62, 679-682. 

Tennant, R.W., Margolin, B.H., Shelby, M.D., 

Zeiger, E., Haseman, J.K., Spalding, J., 

Caspary, W., Resnick, M., Stasiewicz, S., 

• Anderson, B., and Minor, R. (1987). Prediction of 

chemical carcinogenicity in rodents from in vitro 

genetic toxicity assays. Science 236, 933-941. 

Thiedemann, K.-U., Liithe, N., Paulini, I., 

Kreft, A., Heinrich, U., and Glaser, U. (1989). 

Ultrastructural observations in hamster and rat lungs 

after chronic inhalation of cadmium compounds. 

Exp. Pathol. 37, 264-268. 

Tkeshelashvili, L.K., Reid T.M., McBride, T.J., and 

Loeb, L.A. (1993). Nickel induces a signature 

mutation for oxygen free radical damage. Cancer 

Res. 53, 4172-4174. 

Torjussen, W., and Andersen, I. (1979). Nickel 

concentrations in nasal mucosa, plasma, and urine in 

active and retired nickel workers. Ann. Clin. Lab. 

Sci. 9, 289-298. 

United States Bureau of Mines (1984). Nickel. In 

Bureau of Mines Minerals Yearbook 1984. U.S. 

Department of the Interior, Bureau of Mines, 

Washington, DC. 

United States Bureau of Mines (1985a). Nickel. In 

Mineral Facts and Problems, 1985 Edition. U.S. 

Department of the Interior, Bureau of Mines, 

Washington, DC. 

United States Bureau of Mines (1985b). Nickel. In 

Mineral Commodity Summaries. 1985. U.S. 

Department of the Interior, Bureau of Mines, 

Washington, DC. 

United States Bureau of Mines (1991). Nickel. In 

Mineral Commodity Summaries 1991. U.S. 

Department of the Interior, Bureau of Mines, 

Washington, DC. 

United States Environmental Protection Agency 

(USEPA) (1986). Health Assessment Document for 

Nickel and Nickel Compounds (EPA/600/8- 

83/012FF), pp. 1-83. Office of Health and 

Environmental Assessment, Washington, DC. 

Valentine, R., and Fisher, G.L. (1984). Pulmonary 

clearance of intratracheally administered 63Ni3S2 in 

strain A/J mice. Environ. Res. 34, 328-334. 

Waksvik, H., Boysen, M., and H~getveit, A.C. 

(1984). Increased incidence of chromosomal 

aberrations in peripheral lymphocytes of retired 

nickel workers. Carcinogenesis 5, 1525-1527. 

Warner, J.S. (1984). Occupational exposure to 

airborne nickel in producing and using primary nickel 

products. In Nickel in the Human Environment 

(F.W. Sunderman, Jr., A. Aitio, A. Berlin, 

C. Bishop, E. Buringh, W. Davis, M. Gounar, 

P.C. Jacquignon, E. Mastromatteo, J.P. Rigaut, 

C. Rosenfeld, R. Saracci, and A. Sors, Eds.), IARC 

Scientific Publications No. 53, pp. 419-438. Oxford 

University Press, Oxford. 

Weast, R.C., Ed. (1976). Handbook of Chemistry 

and Physics, 56th ed., p. Bl18, entry No. n76. 

CRC Press, Inc., Cleveland. 

Wehner, A.P., Busch, R.H., Olson, R.J., and 

Craig, D.K. (1975). Chronic inhalation of nickel 

oxide and cigarette smoke by hamsters. Am. Ind. 

Hyg. Assoc. J. 36, 801-810. 

Wehner, A.P., Stuart, B.O., and Sanders, C.L. 

(1979). Inhalation studies with Syrian golden 

hamsters. Prog. Exp. Tumor Res. 24, 177-198. 

Wehner, A.P., Dagle, G.E., Clark, M.L., and 

Buschbom, R.L. (1986). Lung changes in rats 

following inhalation exposure to volcanic ash for two 

years. Environ. Res. 40, 499-517. 
References 123 

Weischer, C.H., Oldiges, H., Hochrainer, D., and 

Kordel, W. (1980). Subchronic effects induced by 

NiO-inhalation in Wistar rats. In Mechanisms of 

Toxicily and Hazard Evaluation (B. Holmstedt, 

R. Lauwerys, M. Mercier, and M. Roberfroid, 

Eds.), pp. 555-558. Elsevier North Holland, Inc., 

New York. 

Williams, D.A. (1971). A test for differences 

between treatment means when several dose levels 

are compared with a zero dose control. Biometrics 

27, 103-117. 

Williams, D.A. (1972). The comparison of several 

dose levels with a zero dose control. Biometrics 

28, 519-531. 

World Health Organization (WHO) (1991). 

Environmental Health Criteria 108: Nickel. World 

Health Organization, Geneva. 

Yamashiro, S., Gilman, J.P.W., Hulland, T.J., and 

Abandowitz, H.M. (1980). Nickel sulphide-induced 

rhabdomyosarcomata in rats. Acta Pathol. Jpn. 30, 

9-22. 

Yarita, T., and Nettesheim, P. (1978). 

Carcinogenicity of nickel subsulfide for respiratory 

tract mucosa. Cancer Res. 38, 3140-3145. 

Zeiger, E., Haseman, J.K., Shelby, M.D., 

Margolin, B.H., and Tennant, R.W. (1990), 

Evaluation of four in vitro genetic toxicity tests for 

predicting rodent carcinogenicity: Confirmation of 

earlier results with 41 additional chemicals. Environ. 

Mol. Mutagen. 16 (Suppl. 18), 1-14. 

Zeiger, E., Anderson, B., Haworth, S., Lawlor, T., 

and Mortelmans, K. (1992). Salmonella 

mutagenicity tests: V. Results from the testing of 

311 chemicals. Environ. Mol. Mutagen. 19 

(Suppl. 21), 2-141. 
124 Nickel Oxide, NTP TR 451 
125 

APPENDIX A 

SUMMARY OF LESIONS IN MALE RATS 

IN THE 2-YEAR INHALATION STUDY 

OF NICKEL OXIDE 

TABLE A1 

TABLE A2 

TABLE A3 

TABLE A4a 

TABLE A4b 

TABLE A5 

Summary of the Incidence of Neoplasms in Male Rats 

tn the 2-Year Inhalation Study of Nickel Oxide .......................... 126 

Individual Animal Tumor Pathology of Male Rats 

~n the 2-Year Inhalation Study of Nickel Oxide .......................... 132 

Statistical Analysis of Primary Neoplasms in Male Rats 

In the 2-Year Inhalation Study of Nickel Oxide .......................... 154 

Historical Incidence of Lung Neoplasms 

tn Untreated Male F344/N Rats .................................... 160 

Historical Incidence of Pheochromocytomas of the Adrenal Medulla 

m Untreated Male F344/N Rats .................................... 161 

Summary of the Incidence of Nonneoplastic Lesions in Male Rats 

tn the 2-Year Inhalation Study of Nickel Oxide .......................... 162 
126 Nickel Oxide, NTP TR 451 

TABLE A1 

Summary of the Incidence of Neoplasms in Male Rats in the 2-Year Inhalation Study of Nickel Oxide a 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 

Disposition Summary 

Animals initially in study 65 65 65 

7-Month interim evaluation 6 7 7 

15-Month interim evaluation 5 5 5 

Early deaths 

Moribund 39 35 32 

Natural deaths 1 3 6 

Survivors 

Died last week of study 1 

Terminal sacrifice 14 15 14 

Missexed 

Animals examined microscopically 

65 

7 

5 

36 

4 

1 

11 

1 

65 65 65 64 

Systems Examined At 7 Months With No Neoplasms Observed 

Alimentary System 

Cardiovascular System 

Endocrine System 

General Body System 

Genital System 

Hematopoietic System 

Integumentary System 

Musculoskeletal System 

Nervous System 

Respiratory System 

Special Senses System 

Urinary Syste m 

15-Month Interim Evaluation 

Endocrine System 

Adrenal medulla (5) 

Pheochromocytoma benign 

Pituitary gland (5) 

Pars distalis, adenoma 

Thyroid gland (5) 

C-cell, adenoma 1 (20%) 

(5) 

(5) 

I (20%) 

(5) 

(5) 

2 (40%) 

(5) 

(5) 

I (20%) 

(5) 

(5) 

(5) 

Genital System 

Testes (5) (5) 

Bilateral, interstitial cell, adenoma 

Interstitial cell, adenoma 3 (60%) 4 (80%) 

(5) (5) 

1 (20%) 

3 (60%) 

Integumentary System 

Skin 

Sebaceous gland, adenoma 

(i) 

I (lOO%) 
Lesions in Male Rats 127 

TABLE A1 

Summary of the Incidence of Neoplasms in Male Rats in the 2-Year Inhalation Study of Nickel Oxide (continued) 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 

15-Month Interim Evaluation (continued) 

Systems Examined With No Neoplasms Observed 

Alimentary System 

Cardiovascular System 

General Body System 

Hematopoietic System 

Muscuioskeletal System 

Nervous System 

Respiratory System 

Special Senses System 

Urinary System 

2-Year Study 

Alimentary System 

Intestine large, colon (54) 

Intestine large, rectum (54) 

Anus, leiomyoma 

Intestine large, cecum (54) 

Intestine small, duodenum (54) 

Intestine small, jejunum (54) 

Intestine small, ileum (54) 

Fibroma 

Liver (54) 

Fibrous histiocytoma, metastatic 

Hemangioma 

Hepatocellular carcinoma 2 

Hepatocellular carcinoma, multiple 

Hepatocellular adenoma 3 

Hepatocellular adenoma, multiple 

Histiocytic sarcoma, metastatic, skin 

Mesentery ( 1 ) 

Pancreas (54) 

Salivary glands (54) 

Squamous cell carcinoma 

Stomach, forestomach (54) 

Stomach, glandular (54) 

Tongue 

Squamous cell carcinoma 

(4%) 

(6%) 

(53) 

(53) 

(53) 

(52) 

(53) 

(53) 

1 

(53) 

(1) 

(53) 

(53) 

(53) 

(53) 

(2%) 

(2%) 

(2%) 

(9%) 

(2%) 

(53) 

(52) 

1 (2%) 

(52) 

(53) 

(53) 

(53) 

(53) 

1 (2%) 

1 (2%) 

3 (6%) 

(53) 

(53) 

1 (2%) 

(53) 

(53) 

(1) 

1 (100%) 

(52) 

(52) 

(51) 

(52) 

(52) 

(51) 

(52) 

1 

1 

(1) 

(52) 

(52) 

(52) 

(52) 

(2%) 

(2%) 

(4%) 

(2%) 

Cardiovascular System 

Heart 

Carcinoma, metastatic, lung 

(54) (53) (53) (52) 

1 (2%) 

Endocrine System 

Adrenal cortex 

Adenoma 

(54) (53) 

1 (2%) 

(53) (52) 
128 Nickel Oxide, NTP TR 451 

TABLE A1 

Summary of the Incidence of Neoplasms in Male Rats in the 2-Year Inhalation Study of Nickel Oxide (continued) 

0 mg/m ~ 0.62 mg/m ~ 1.25 mg/m 5 2.5 mg/m 5 

2-Year Study (continued) 

Endocrine System (continued) 

Adrenal medulla (54) (52) (53) (52) 

Pheochromocytoma malignant 1 (2%) 6 (12%) 

Pheochromocytoma benign 17 (31% ) 13 (25 %) 17 (32 %) 16 (31%) 

Bilateral, pheochromocytoma benign 10 (19%) 11 (21%) 9 (17%) 16 (31%) 

Islets, pancreatic (54) (53) (53) (52) 

Adenoma 2 (4%) 2 (4%) 2 (4%) 2 (4%) 

Adenoma, multiple 1 (2%) 

Carcinoma 1 (2%) 1 (2%) 2 (4%) 

Parathyroid gland (50) (50) (49) (49) 

Adenoma I (2%) 1 (2%) 1 (2%) 

Pituitary gland (53) (52) (52) (52) 

Pars distalis, adenoma 24 (45%) 18 (35%) 16 (31%) 12 (23%) 

Pars intermedia, carcinoma 1 (2%) 

Thyroid gland (54) (53) (52) (52) 

C-cell, adenoma 6 (11%) 5 (9%) 4 (8%) 2 (4%) 

C-cell, carcinoma 1 (2%) 1 (2%) 

Follicular cell, adenoma 1 (2%) 3 (6%) 2 (4%) 1 (2%) 

Follicular cell, carcinoma 1 (2%) 1 (2%) 

General Body System 

Tissue NOS 

Basal cell carcinoma 

Carcinoma, metastatic, lung 

Fibrosarcoma 

Lipoma 

Oral, osteosarcoma 

(3) (2) (2) 

1 (33%) 

2 (100%) 

(4) 

1 (25%) 

1 (25%) 

1 (25%) 

Genital System 

Epididymis 

Preputial gland 

Adenoma 

Carcinoma 

Fibrous histiocytoma 

Prostate 

Adenoma 

Seminal vesicle 

Testes 

Bilateral, interstitial cell, adenoma 

Interstitial cell, adenoma 

(54) 

(54) 

1 (2%) 

(53) 

(54) 

(54) 

20 (37%) 

20 (37%) 

(53) 

(53) 

3 

1 

(53) 

(53) 

(53) 

36 

10 

(6%) 

(2%) 

(68%) 

(19%) 

(53) 

(53) 

2 (4%) 

1 (2%) 

(53) 

1 (2%) 

(53) 

(53) 

27 (51%) 

16 (30%) 

(52) 

(51) 

2 

1 

(52) 

(52) 

(52) 

26 

21 

(4%) 

(2%) 

(50%) 

(40%) 

Hematopoietic System 

Bone marrow 

Lymph node 

Lymph node, bronchial 

Lymph node, mandibular 

Squamous cell carcinoma, metastatic 

Lymph node, mesenteric 

Lymph node, mediastinal 

(54) 

(16) 

02) 

(49) 

(54) 

(47) 

(53) 

(19) 

(51) 

(51) 

(53) 

(52) 

(53) 

(16) 

(53) 

(50) 

1 (2%) 

(53) 

(52) 

(52) 

(15) 

(52) 

(51) 

(51) 

(52) 
Lesions in Male Rats 129 

TABLE A1 

Summary of the Incidence of Neoplasms in Male Rats in the 2-Year Inhalation Study of Nickel Oxide (continued) 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 

2-Year Study (continued) 

ttematopoietic System (continued) 

Spleen (54) 

Fibrosarcoma 

Pheochromocytoma malignant, metastatic 

Thymus (44) 

Carcinoma, metastatic, lung 

(53) (53) (52) 

1 (2%) 

(49) (47) 

1 (2%) 

(48) 

1 (2%) 

Integumentary System 

Mammary gland (54) 

Fibroadenoma 2 (4%) 

Skin (13) 

Basal cell adenoma 2 (15%) 

Fibroma 3 (23%) 

Keratoacanthoma 1 (8%) 

Lipoma 

Papilloma 

Squamous cell carcinoma 

Squamous cell papilloma 

Trichoepithelioma 

Scrotum, fibroma 

Subcutaneous tissue, histiocytic sarcoma 

Subcutaneous.tissue, neurofibrosarcoma 1 (8%) 

Subcutaneous tissue, sarcoma 

(53) (53) 

1 (2%) 

(4) (14) 

I (7%) 

I (25%) 1 (7%) 

1 (25%) 1 (7%) 

1 (7%) 

i (25%) 

1 (25%) (7%) 

(7%) 

(7%) 

(7%) 

(52) 

(6) 

1 (17%) 

I (17%) 

1 (17%) 

Musculoskeletal System 

Bone 

Pelvis, hemangiosarcoma 

Skeletal muscle 

Fibrous histiocytoma 

(54) (53) (53) 

1 (2%) 

(52) 

(1) 

1 (lOO%) 

Nervous System 

Brain 

Astrocytoma NOS 

Granular cell tumor NOS 

Peripheral nerve 

Ganglion, paraganglioma benign 

(54) 

(1) 

1 (100%) 

(53) 

1 (2%) 

(53) 

1 (2%) 

(52) 

(1) 

1 (lOO%) 

Respiratory System 

Lung 

Alveolar/bronchiolar adenoma 

Alveolar/bronchiolar carcinoma 

Alveolar/bronchiolar carcinoma, squamous 

differentiation 

Fibrous histiocytoma, metastatic 

Histiocytic sarcoma, metastatic, skin 

Pheochromocytoma malignant, metastatic 

Squamous cell carcinoma 

Nose 

(54) 

1 (2%) 

(54) 

(53) 

t (2%) 

(53) 

(53) 

3 (6%) 

1 (2%) 

2 (4%) 

(53) 

(52) 

2 (4%) 

2 (4%) 

1 (2%) 

1 (2%) 

1 (2%) 

(52) 
130 Nickel Oxide, NTP TR 451 

TABLE A1 

Summary of the Incidence of Neoplasms in Male Rats in the 2-Year Inhalation Study of Nickel Oxide (continued) 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 

2-Year Study (continued) 

Special Senses System 

Ear 

Fibroma 

Eye 

Lids, fibroma 

Harderian gland 

Carcinoma 

Zymbal's gland 

Carcinoma 

(1) 

1 (10o%) 

(9) (5) (3) (5) 

1 (20%) 

(1) 

1 (10o%) 

(1) 

1 (lOO%) 

Urinary System 

Kidney (54) (53) (53) (52) 

Histiocytic sarcoma, metastatic, skin 1 (2%) 

Renal tubule, adenoma 1 (2%) 

Transitional epithelium, carcinoma 1 (2%) 

Urinary bladder (54) (53) (53) (52) 

Systemic Lesions 

Multiple organs b 

Histiocytic sarcoma 

Leukemia mononuclear 

Mesothelioma malignant 

(54) (53) (53) (52) 

1 (2%) 

31 (57%) 32 (60%) 26 (49%) 35 (67.%) 

1 (2%) 2 (4%) 

Neoplasm Summary 

Total animals with primary neoplasms c 

15-Month interim evaluation 4 4 3 5 

2-Year study 53 53 53 52 

Total primary neoplasms 

15-Month interim evaluation 4 5 3 5 

2-Year study 154 157 159 157 

Total animals with benign neoplasms 

15-Month interim evaluation 4 4 3 5 

2-Year study 52 51 52 52 

Total benign neoplasms 

15-Month interim evaluation 4 5 3 5 

2-Year study 114 117 116 105 

Total animals with malignant neoplasms 

2-Year study 37 38 35 43 

Total malignant neoplasms 

2-Year study 40 39 42 52 
Lesions in Male Rats 131 

TABLE AI 

Summary of the Incidence of Neoplasms in Male Rats in the 2-Year Inhalation Study of Nickel Oxide (continued) 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 

Neoplasm Summary (continued) 

Total animals with metastatic neoplasms 

2-Year study I 1 

Total metastatic neoplasms 

2-Year study 3 I 

Total animals with uncertain neoplasmsbenign or malignant 

2-Year study 1 1 

Total uncertain neoplasms 

2-Year study 1 1 

6 

19 

a Number of animals examined microscopically at the site and the number of animals with neoplasm 

b Number of animals with any tissue examined microscopically 

c Primary neoplasms: all neoplasms except metastatic neoplasms 
132 Nickel Oxide, NTP TR 451 

TABLE A2 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Inhalation Study of Nickel Oxide: 0 mg/m ~ 

Number of Days on Study 

1455555555555556666666666 

8700266677888992222222225 

7539466933145482222448896 

Carcass ID Number 

0000000000000000000000000 

23342051351 14341244051405 

1921934739560778449 1 64372 

Alimentary System 

Esophagus 

Intestine large, colon 

Intestine large, rectum 

Intestine large, cecum 

Intestine small, duodenum 

Intestine small, jejunum 

Intestine small, ileum 

Liver 

Hepatocellular carcinoma 

Hepatoeellular adenoma 

Mesentery 

Pancreas 

Salivary glands 

Stomach, forestomach 

Stomach, glandular 

+++++ + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + ÷ + + + 

+ + + ÷ + + + + + + + + + + + + + + -I- + + + + + + 

+++÷+ + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

+ ++++ + + + + + + + + + + + + + + + + + + + + 

+++++÷+++++÷+++++++++++4-+ 

+++++++++++++++++++++++q--iX X 

X X 

+ ++++ + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

Cardiovascular System 

Blood vessel 

Heart +++++ + + + + + + + + + + + + + + + + + + + + 

Endocrine System 

Adrenal cortex 

Adrenal medulla 

Pheochromocytoma benign 

Bilateral, pheoehromocytoma benign 

Islets, pancreatic 

Adenoma 

Carcinoma 

Parathyroid gland 

Adenoma 

Pituitary gland 

Pars distalis, adenoma 

Thyroid gland 

C-cell, adenoma 

C-cell, carcinoma 

Follicular cell, adenoma 

Follicular cell, carcinoma 

+++++ + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + -I- + + + + + + 

X X X X X 

X X X X 

++ +++ + + + + + + + + + + + + + + + + + + + + 

M++++M++++++++ ++M+++ ++ +++ 

+++÷+ + + + + + + + + + + + + + + + + + + + + 

X X XXXX XX X 

+ ++++ + + + + + + + + + + + + + + + + + + + + 

X 

General Body System 

Tissue NOS 

Oral, osteosarcoma 

+ + + 

X 

Genital System 

Coagulating gland 

Epididymis 

Preputial gland 

Adenoma 

Prostate 

+ + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

+ + +++ + + + + + + + + + + + + + + + + + + + + 

+++++M+ + + + + + + + + + + + + + + + + + + 

+: Tissue examined microscopically M: Missing tissue X: Lesion present 

A: Autolysis precludes examination I: Insufficient tissue Blank: Not examined 
Lesions in Male Rats 133 

TABLE A2 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Inhalation Study of Nickel Oxide: 0 mg/m 3 (continued) 

Number of Days on Study 

66666666677777777777777777777 

66789999900 1 1 I 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 

19822679955 33543 333 3666666777 

Carcass ID Number 

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Total 

4 0 5 4 3 1 1 3 3 0 5 3 4 2 5 0 0 0 2 6 0 1 2 4 6 6 1 5 6 Tissues/ 

8 6 8 5 4 0 1 0 1 2 7 5 2 8 0 5 8 9 3 3 4 3 6 6 0 4 2 3 1 Tumors 

Alimentary System 

Esophagus + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 54 

Intestine large, colon + + + + + + + + + + + + + + + + + + + + + + + ~ + + + + + 54 

Intestine large, rectum + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 54 

Intestine large, cecum + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 54 

Intestine small, duodenum + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 54 

Intestine small, jejunum + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 54 

Intestine small, ileum + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 54 

Liver + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 54 

Hepatocellular carcinoma 2 

Hepatocellular adenoma X 3 

Mesentery + 1 

Pancreas + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 54 

Salivary glands + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 54 

Stomach, forestomach + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 54 

Stomach, glandular + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 54 

Cardiovascular System 

Blood vessel + + 2 

Heart + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 54 

Endocrine System 

Adrenal cortex + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 54 

Adrenal medulla + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 54 

Pheochromocytoma benign X X X X X X X X X X X X 17 

Bilateral, pheochromocytoma benign X X X X X X 10 

Islets, pancreatic + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 54 

Adenoma X X 2 

Carcinoma X 1 

Parathyroid gland + + + + + + + + + M + + + + + + + + + + + + + + + + + + + 50 

Adenoma X 1 

Pituitary gland + + + + + + + + + + + + + + + + + + + + + + M + + + + + + 53 

Pars distalis, adenoma X X X X X X X X X X X X X X X 24 

Thyroid gland + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 54 

C-cell, adenoma X X X X X 6 

C-cell, carcinoma X 1 

Follicular cell, adenoma X 1 

Follicular cell, carcinoma X 1 

General Body System 

Tissue NOS 3 

Oral, osteosarcoma 1 

Genital System 

Coagulating gland + 4 

Epididymis + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 54 

Preputial gland + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 54 

Adenoma X I 

Prostate + + + + + + + + + + + + + + + + ÷ + + + + + + + + + + + + 53 
134 Nickel Oxide, NTP TR 451 

TABLE A2 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Inhalation Study of Nickel Oxide: 0 mg/m 3 (continued) 

Number of Days on Study 

1455555555555556666666666 

8700266677888992222222225 

7539466933 145482222448896 

Carcass ID Number 

0000000000000000000000000 

2334205135 1 1434124405 1405 

1921934739560778449164372 

Genital System (continued) 

Seminal vesicle 

Testes 

Bilateral, interstitial cell, adenoma 

Interstitial cell, adenoma 

+++++ + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

X X X X 

X XX XXX XX X X X 

Hematopoietic System 

Bone marrow 

Lymph node 

Lymph node, bronchial 

Lymph node, mandibular 

Lymph node, mesenteric 

Lymph node, mediastinal 

Spleen 

Thymus 

+++++ + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

++M+++++++++++++++ +++++++ 

+++++ + + + + + + + + + + + + + + + + + + + + 

+M++M+++++++++ +++++M+ ++++ 

+++++ + + + + + + + + + + + + + + + + + + + + 

++M++ + + + + + + + +I + + +I + + + +I + + 

Integumentary System 

Mammary gland 

Fibroadenoma 

Skin 

Basal cell adenoma 

Fibroma 

Keratoacanthoma 

Subcutaneous tissue, 

neurofibrosarcoma 

+++++ + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + 

X X 

X 

Musculoskeletal System 

Bone +++++ + + + + + + + + + + + + + + + + + + + + 

Nervous System 

Brain 

Peripheral nerve 

Ganglion, paraganglioma benign 

+++++ + + + + + + + + + + + + + + + + + + + + 

+ 

X 

Respiratory System 

Larynx 

Lung 

Squamous cell carcinoma 

Nose 

Trachea 

+++++++ + +I + + + ++ + + + + + + + + + 

+++++ + + + + + ++ + + + + + + + + + + + + + 

++ +++ + + + + +.+ + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

Special Senses System 

Eye 

Zymbal's gland 

Carcinoma 

++ + 

+ 

X 

+ + + 

Urinary System 

Kidney 

Urinary bladder 

+++++ + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

Systemic Lesions 

Multiple organs 

Leukemia mononuclear X X X XX X XX X XX X XX X X 
Lesions in Male Rats 135 

TABLE A2 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Inhalation Study of Nickel Oxide: 0 mg/m 3 (continued) 

Number of Days on Study 

66666666677777777777777777777 

667899999001 1 1233333333333333 

19822679955335433333666666777 

Carcass ID Number 

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Total 

4 0 5 4 3 1 I 3 3 0 5 3 4 2 5 0 0 0 2 6. 0 1 2 4 6 6 1 5 6 Tissues/ 

8 6 8 5 4 0 1 0 1 2 7 5 2 8 0 5 8 9 3 3 4 3 6 6 0 4 2 3 1 Tumors 

Genital System (continued) 

Seminal vesicle 

Testes 

Bilateral, interstitial cell, adenoma 

Interstitial cell, adenorna 

+ + + + + + + + + + .+ + + + + + + + + + + + + + + + + + + 54 

+++++ + + + + ++ + ++ + + + + ++ + + + + + + + + + 54 

X X X X X X X X X X X X X X X X 20 

X X X XX X X X X 20 

Hematopoietic System 

Bone marrow 

Lymph node 

Lymph node, brOnchial 

Lymph node, mandibular 

Lymph node, mesenteric 

Lymph node, mediastinal 

Spleen 

Thymus 

+++++ + + + + + + + + + + + + + + + + + + + + + + + + 54 

++ + + + + + + 16 

+++++I +I +++++++++++++++++ +++ + 52 

+++M+ + +M+ +M+ + + + + + + + + + + + + +M+ + + 49 

+++++ + + + + + ++ + +++ + + + + + + + + + + + + + 54 

+ + + + + + M + + I + M + + + M+ + + + + + + + + + + + + 47 

+++++++++++++++++++++++++ ++ ++ 54 

++MM++M++M+++++++M+M+++++ ++ ++ 44 

Integumentary System 

Mammary gland 

Fibroadenoma 

Skin 

Basal cell adenoma 

Fibroma 

Keratoacanthoma 

Subcutaneous tissue, 

neurofibrosarcoma 

+++++ ++ + + + + + + + + + + + + + + + + + + + + + + 54 

X X 2 

+ + + + + + 13 

X X 2 

X 3 

1 

Musculoskeletal System 

Bone +++++++++++++++ ++++++++ + +++ ++ 54 

Nervous System 

Brain 

Peripheral nerve 

Ganglion, paraganglioma benign 

+++++ + + + + + + + + + + + + + + + + + + + + q- + + + 54 

1 

1 

Respiratory System 

Larynx 

Lung 

Squamous cell carcinoma 

Nose 

Trachea 

++++++++++++++ ++++ +++++++ + ++ + 52 

+++++ +++++++++ +++++++++++ ++ + + 54 

X 1 

+++++ + + + + + + + + + + + + + + + + + + + + + + + + 54 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + 53 

Special Senses System 

Eye 

Zymbal's gland 

Carcinoma 

+ + + 

Urinary System 

Kidney 

Urinary bladder 

+++++ + + + + + + + + + + + + + + + + + + + + + + + + 54 

+++++ + + + + + + + + + + + + + + + + + + + + + + + + 54 

Systemic Lesions 

Multiple organs 

Leukemia mononuclear 

+ + + + + + + + + + + + + ++ + + + + + + + + + + + + + + 54 

X X X X X X X X X X X X X X X 31 
136 Nickel Oxide, NTP TR 451 

TABLE A2 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Inhalation Study of Nickel Oxide: 0.62 mg/m 3 

Number of Days on Study 

4555555555555666666666666 

60122346677791 12234447777 

6390482470025883933790599 

Carcass ID Number 

1 1 1 1 1 1 1 I 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 

4646687354874575754478469 

5095649976947320062 1 6 1 873 

Alimentary System 

Esophagus 

Intestine large, colon 

Intestine large, rectum 

Intestine large, cecum 

Intestine small, duodenum 

Intestine small, jejunum 

Intestine small, ileum 

Fibroma 

Liver 

Hemangioma 

Hepatocellular carcinoma 

He#atocellular adenoma 

Hepatocellular adenoma, multiple 

Mesentery 

Mesothelioma malignant, metastatic 

Pancreas 

Salivary glands 

Stomach, forestomach 

Stomach, glandular 

+ + +++ + + + + + + + + + + + + + + + + + + + + 

+ + +++ + + + + + + + + + + + + + + + + + + + + 

+ ++++ + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

X 

+ 

X 

+ + +++ + + + + + + + + + + + + + + + + + + + + 

+ ++++ + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

++ +++ + + + + + + + + + + + + + + + + + + + + 

Cardiovascular System 

Heart + + + + + + + + + + + + + + + + + + + + + + + + + 

Endocrine System 

Adrenal cortex + + + + + + + + + + + + + + + + + + + + + + + + + 

Adenoma 

Adrenal medulla 

Pheochromocytoma benign 

Bilateral, pheochromocytoma benign 

Islets, pancreatic 

Adenoma 

Adenoma, multiple 

Carcinoma 

Parathyroid gland 

Adenoma 

Pituitary gland 

Pars distalis, adenoma 

Thyroid gland 

C-cell, adenoma 

Follicular cell, adenoma 

+ + +++ + +M + + + + + + + + + + + + + + + + + 

XX X X X X 

X X X X 

++ +++ + + + + + + + + + + + + + + + + + + + + 

++M++ + + + + + + + + + + + + + + + + +M+ + 

++++++M+ ++++ + +++++++ + + + ++ 

X X X X X • 

+ + +++ + + + + + + + + + + + + + + + + + + + + 

X X X 

X X 

General Body System 

Tissue NOS + 

Mesothelioma malignant, metastatic X 
Lesions in Male Rats 137 

TABLE A2 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Inhalation Study of Nickel Oxide: 0.62 mg/m 3 

(continued) 

Number of Days on Study 

6666677777777777777777777777 

889990 0 00 1 1 1 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 

56677 034 9277 03 3 3 3 3 3 3 3 6 6 6 6 67 7 

Carcass ID Number 

11111 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Total 

43738 645 3 967 5 3 5 67 7 8 8 95 67 8 8 8 9 Tissues/ 

06732 9 3 8 2 2 8 1 2 8 1 1 3 8 6 8 4 5 4 5 0 5 7 0 Tumors 

Alimentary System 

Esophagus + + + + + + + + + + + + + + + + + + + + + + + + + + + + 53 

Intestine large, colon + + + + + + + + + + + + + + + + + + + + + + + "+ + + + + 53 

Intestine large, rectum + + + + + + + + + + + + + + + + + + + + + + + + + + + + 53 

Intestine large, cecum + + + + + + + + + + + + + + + + + + + + + + + + + + + + 53 

Intestine small, duodenum + + + + + + + + + + M + + + + + + + + + + + + + + + + + 52 

Intestine small, jejunum + + + + + + + + + + + + + + + + + ++ + + + + + + + + + 53 

Intestine small, ileum + + + + + + + + + + + + + + + + + + + + + + + + + + + + 53 

Fibroma X 1 

Liver + + + + + + + + + + + + + + + + + + + + + + + + + + + + 53 

Hemangioma X 1 

Hepatocellular carcinoma X 1 

Hepatocellular adenoma X X X X 5 

Hepatocellular adenoma, multiple X 1 

Mesentery 1 

Mesothelioma malignant, metastatic 1 

Pancreas + + + + + + + + + + + + + + + + + + + + + + + + + + + + 53 

Salivary glands + + + + + + + + + + + + + + + + + + + + + + + + + + + + 53 

Stomach, forestomach + + + + + + + + + + + + + + + + + + + + + + + + + + + + 53 

Stomach, glandular + + + + + + + + + + + + + + + + + + + + + + + + + + + + 53 

Cardiovascular System 

Heart + + + + + + + + + + + + + + + + + + + + + + + + + + + + 53 

Endocrine System 

Adrenal cortex 

Adenoma 

Adrenal medulla 

Pheochromocytoma benign 

Bilateral, pheochromocytuma benign 

Islets, pancreatic 

Adenoma 

Adenoma, multiple 

Carcinoma 

Parathyroid gland 

Adenoma 

Pituitary gland 

Pars distalis, adenoma 

Thyroid gland 

C-cell, adenoma 

Follicular cell, adenoma " 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 53 

X 1 

++++++++++++++++ + +++ +++++ + ++ 52 

X X X X X X X 13 

X X X X X X X 1! 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 53 

X X 2 

X 1 

X 1 

++++M++++++++ + +++++++++ + ++ + + 50 

X 1 

++++++ ++++++ ++++++ + + + ++++ + + + 52 

XX X XX X XX X X X X X 18 

+ ++++ + + + + + + + + + + + + + + + + + + + + + + + 53 

X X 5 

X 3 

General Body System 

Tissue NOS 

Mesothelioma malignant, metastatic 
138 Nickel Oxide, NTP TR 451 

TABLE A2 

Individual Animal Tumor Pathology of Male Rats in the 2-Year 

(continued) 

Inhalation Study of Nickel Oxide: 0.62 mg/m 3 

Number of Days on Study 

455555555 

601223466 

639048247 

5555666666666666 

77791.12234447777 

0025883933790599 

Carcass ID Number 

1111111111111111111111111 

4646687354874575754478469 

5095649976947320062161873 

Genital System 

Epididymis 

Mesothelioma malignant, metastatic 

Preputial gland 

Adenoma 

Fibrous histiocytoma 

Prostate 

Seminal vesicle 

Testes 

Bilateral, interstitial cell, adenoma 

Interstitial cell, adenoma 

+ ++++ + + + + + + + + 

X 

+++++ + + + + + + + + 

X 

X 

+++++ + + + + + + + + 

+ + +++ + + + + + + + + 

+++++ + + + + + + + + 

XX XXX 

X X X 

+ 

+ 

+ + + + + + + + + + + 

+ + + + + + + + + + + 

x 

+ + + + + + + + + + + + 

+ + + + + + + + + + + + 

+ + + + + + + + + + + + 

X X XXX XX 

X X X X 

Hematopoietic System 

Bone marrow 

Lymph node 

Lymph node, bronchial 

Lymph node, mandibular 

Lymph node, mesenteric 

Lymph node, mediastinal 

Spleen 

Thymus 

+++++ + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + 

+++M+ + + + ++ + + + + + +M+ + + + + + + + 

+++++ + + + + + + + + + + +M+ + + + + + + + 

+ ++++ + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + +M+ + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

Integumentary System 

Mammary gland 

Skin 

Fibroma 

Keratoacanthoma 

Squamous cell carcinoma 

Squamous cell papilloma 

+++++ + + + + + + + + + + + + + + + + + + + + 

+ + 

X 

X 

X 

Musculoskeletal System 

Bone 

Pelvis, hemangiosarcoma 

+ ++++ + + + + + + + + + + + + + + + + + + + + 

Nervous System 

Brain 

Granular cell tumor NOS 

++++++++++4-++++++++++++++ 

X 

Respiratory System 

Larynx 

Lung 

Alveolar/bronchiolar adenoma 

Nose 

Trachea 

+++++++++++++++++++++++4-+ 

+ ++++ + + + + + + + + + + + + + + + + + + + + 

X 

++++++++++++++4-++++++4-+++ 

++ +++ + + + + + + + + + + + + + + + + + + + + 

Special Senses System 

Eye 

Lids, fibroma 

Harderian gland 

Carcinoma 

+ + 

+ 

X 
Lesions in Male Rats 139 

TABLE A2 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Inhalation Study of Nickel Oxide: 0.62 mg/m 3 

(continued) 

Number of Days on Study 

6666677777777777777"777777777 

8 8 999 0 0 0 0 1 1 1 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 

5667703492770333333336666677 

Carcass ID Number 

11111 1 1 1 1 1 1 I 1 1 1 1 1 1 1 I I 1 1 1 1 1 1 1 Total 

43 738 6 4 5 3 9 6 7 5 3 5 6 7 7 8 8 9 5 6 7 88 8 9 Tissues/ 

067329382281281 1386845450570 Tumors 

Genital System 

Epididyrnis 

Mesothelioma malignant, metastatic 

Preputial gland 

Adenoma 

Fibrous histiocytoma 

Prostate 

Seminal vesicle 

Testes 

Bilateral, interstitial cell, adenoma 

Interstitial cell, adenoma 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

+++÷+ + + + + + + + + + + + + + + + + + + + + + + + 

X 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + +.+ + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

XX X XXXXXXXXXXXXXXXXXXXXX 

XX X 

53 

1 

53 

3 

1 

53 

53 

53 

36 

10 

Hematopoietic System 

]lone ma~ow 

Lymph node 

Lymph node, bronchial 

Lymph node, mandibular 

Lymph node, mesenteric 

Lymph node, mediastinal 

Spleen 

Thymus 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

++++++++++++++M++++++++++ +++ 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

+++++ + + +M+ + +M+ + + + + + + + + + +M+ +M 

53 

19 

51 

51 

53 

52 

53 

49 

Integumentary System 

Mammary gland 

Skin 

Fibroma 

Keratoacanthoma 

Squamous cell carcinoma 

Squamous cell papilloma 

+ + +++ + + +'+ + + + + + + + + + + + + + + + + + + + 

+ + 

X 

53 

4 

1 

1 

1 

1 

Musculoskeletal System 

Bone 

Pelvis, hemangiosarcoma 

+.4-++++++++++++++++++++++++++ 

X 

53 

I 

Nervous System 

Brain 

Granular cell tumor" NOS 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 53 

1 

Respiratory System 

Larynx 

Lung 

Alveolar/bronchiolar adenoma 

Nose 

Trachea 

+ + + + q- + + + + + + + + + + + + q- + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + ÷ 

÷++++ + + ÷ + + + + + + + + + + + + + + + + + + + + 

52 

53 

1 

53 

53 

Special Senses System 

Eye 

Lids, fibroma 

Harderian gland 

Carcinoma 

+ + ÷ 

X 
140 Nickel Oxide, NTP TR 451 

TABLE A2 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Inhalation Study of Nickel Oxide: 0.62 mg/m 3 

(continued) 

Number of Days on Study 

4555555555555666666666666 

60122346677791 12234447777 

6390482470025883933790599 

Carcass ID Number 

1111111111111111111111111 

464668735487457575447846-9 

5095649976947320062161873 

Urinary System 

Kidney 

Urinary bladder 

+ + +++ + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

Systemic Lesions 

Multiple organs 

Leukemia mononuclear 

Mesothelioma malignant 

X X X X XX XXXX XXXXXXXX 

X 
Lesions in Male Rats 141 

TABLE A2 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Inhalation Study of Nickel Oxide: 0.62 mg/m 3 

(continued) 

Number of Days on Study 

6666677777777777777777777777 

8899900001 1 12333333333333333 

56"67703492770333333336666677 

Carcass ID Number 

1 1 111 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I 1 1 1 1 Total 

4373864539675356778895678889 Tissues/ 

067329382281281 1386845450570 Tumors 

Urinary System 

Kidney 

Urinary bladder 

--F + + + + ÷ + --I- -F ÷ ..F -I- + --F + -I- -I- + + ÷ ..F ÷ --I- + -F + + + 

+ + ÷ + ÷ -I- + + + + + + -F + + -I- ÷ ÷ ÷ -I- + ÷ -F-~ + + + + 

53 

53 

Systemic Lesions 

Multiple organs 

Leukemia mononuclcar 

Mcsothelioma malignant 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

XXXX X X XXXX X X X X 

53 

32 

l 
142 Nickel Oxide, NTP TR 451 

TABLE A2 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Inhalation Study of Nickel Oxide: 1.25 mg/m 3 

Number of Days on Study 

2345555555555566666666666 

0651244666778901 1 1 1222445 

2779516477088268899047770 

Carcass ID Number 

2333233223332222222332232 

6122912891018876969007928 

7143092378822159235404814 

Alimentary System 

Esophagus 

Intestine large, colon 

Intestine large, rectum 

Anus, leiomyoma 

Intestine large, cecum 

Intestine small, duodenum 

Intestine small, jejunum 

Intestine small, ileum 

Liver 

Hepatocellular carcinoma 

Hepatocellular carcinoma, multiple 

Hepatocellular adenoma 

Pancreas 

Salivary glands 

Squamous cell carcinoma 

Stomach, forestomach 

Stomach, glandular 

Tongue 

Squamous cell carcinoma 

+++++ + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

++++++++++M++ ++ +++++ + ++ ++ 

X 

+++++ + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

+ ++++ + + + + + + + + + + + + + + + + + + + + 

+++~+ + + + + .+ + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

X 

X X 

+++++ + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

X 

+++++ + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

Cardiovascular System 

Blood vessel 

Heart ++ +++ + + + + + + + + + + + + + + + + + + + + 

Endocrine System 

Adrenal cortex 

Adrenal medulla 

Pheochromocytoma malignant 

Pheochromocytoma benign 

Bilateral, pheochromocytoma benign 

Islets, pancreatic 

Adenoma 

Carcinoma 

Parathyroid gland 

Adenoma 

Pituitary gland 

Pars distalis, adenoma 

Pars intermedia, carcinoma 

Thyroid gland 

C-cell, adcnoma 

C-cell, carcinoma 

Follicular cell, adenoma 

+ ++++ + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

X 

X X X X X 

+++++ + + + + + + + + + + + + + + + + + + + + 

X 

+++M+ + + + + + + + + + + + + + + + + + + + + 

+÷+++ + + + + + + + + + + W + + + + + + + + + 

X X X XXX 

+++M+++++++++++++ +++++ +++ 

General Body System 

Tissue NOS 

Lipoma 

+ 

X 
Lesions in Male Rats 143 

TABLE A~ 

Individual Animal Tumor Pathology of 

(continued) 

Male Rats in the 2-Year Inhalation Study of Nickel Oxide: 1.25 mg/m 3 

Number of Days on Study 

6666666777777777777777777777 

7788999000013333333333333333 

4611007666770333333334666677 

Carcass ID Number 

2 3 3 3 2 2 2 2 2 2 3 2 2 2 2 2 2 2 2.2 3 2 2 2 3 3 3 3 

8 1 127 9 8 67 8 0 7 6 6 6 7 8 8 9 9 1 9 6 6 0 0 0 I 

0605097539394188583641265793 

T6tal 

Tissues/ 

Tumors 

Alimentary System 

Esophagus 

Intestine large, colon 

Intestine large, rectum 

Anus, leiomyoma 

Intestine large, cecum 

Intestine small, duodenum 

Intestine small, jejunum 

Intestine small, ileum 

Liver 

Hepatocellular carcinoma 

Hepatocellular carcinoma, multiple 

Hepatocellular adenoma 

Pancreas 

Salivary glands 

Squamous cell carcinoma 

Stomach, forestomach 

Stomach, glandular 

Tongue 

Squamous cell carcinoma 

+ + + + + + + + + + + + + + + + + + + -t- + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + W -b + + + 

++A ++ + + + + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

+++++ + + q- + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + .q- + + + + + + + + 

X 

X 

+ + + + + + -t- + + + -I- + + + + + + + ~- + + + + + + + + + 

+ + + + + + + + + q- + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

++ +++ + + + + + + + + + + + + + + + + + + + + + + + 

+ 

X 

53 

53 

52 

1 

52 

53 

53 

53 

53 

1 

1 

3 

53 

53 

1 

53 

53 

I 

1 

Cardiovascular System 

Blood vessel 

Heart 

+ 

+ + + + + + + + + + + + + + + + + + + + + + + + -t- + + + 

1 

53 

Endocrine System 

Adrenal cortex 

Adrenal medulla 

Pheochromocytoma malignant 

Pheochromocytoma benign 

Bilateral, pheochromocytoma benign 

Islets, pancreatic 

Adenoma 

Carcinoma 

Parathyroid gland 

Adenoma 

Pituitary gland 

Pars distalis, adenoma 

Pars intermedia, carcinoma 

Thyroid gland 

C-cell, adenoma 

C-cell, carcinoma 

Follicular cell, adenoma 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

+ ++++ + + + + + + + + + + + + + + + + + + + + + + + 

X XXXX X XXXXX X 

XXX X XXX X X 

+ + + + + + + + + + + + + + + + + + + + + + + ..F -t- + + + 

X X 

X 

++M++ + + + + + + + + + + +M+ + +M+ + + + + + + 

X 

+++++ + + + + ++ + + + + +M+ + + + + + + + + + + 

XX X XX X XX X X 

X 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + 

X X X X 

X X 

53 

53 

1 

17 

9 

53 

2 

2 

49 

1 

52 

16 

1 

52 

4 

1 

2 

General Body System 

Tissue NOS 

Lipoma 

+ 2 

X 2 
144 Nickel Oxide, NTP TR 451 

TABLE A2 

Individual Animal Tumor Pathology of Mate Rats in the 2-Year Inhalation Study of Nickel Oxide: 

(continued) 

1.25 mg/m 3 

Number of Days on Study 

2345555555555566666666666 

065124466677890 1 1 1 1 222445 

27795 1 6477088268899047770 

Carcass ID Number 

23332332233322222223 32232 

61229 1 289 1 0 1 8876969007928 

7143092378822 1 592354048 1 4 

Genital System 

Epididymis + + + + + + + + + + + 

Preputial gland + + + + + + + + + + + 

Adenoma 

Carcinoma 

Prostate + + + + + + + + + + + 

Adenoma 

Seminal vesicle + + + + + + + + + + + 

Testes + + + + + + + + + + + 

Bilateral, interstitial cell, adenoma X 

.Interstitial cell, adenoma X X X X X 

+ 

+ 

X 

X 

+ 

+ + + + + + + + + + + + + 

+ + + + + + + + + + + + + 

+ + + + + + + + + + + + + 

+ + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + 

XX XXXX XXX 

X X X 

Hematopoietic System 

Bone marrow 

Lymph node 

Lymph node, bronchial 

Lymph node, mandibular 

Squamous cell carcinoma, metastatic 

Lymph node, mesenteric 

Lymph node, mediastinal 

Spleen 

Fibrosarcoma 

Thymus 

+ ++++ + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + 

+ + +++ + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

X 

+++++ + + + + + + + + + + + + + + + + + + + + 

+ + +++ + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + +MM+ + + + + + + + + + + 

Integumentary System 

Mammary gland + + + + + + + + + + + + + + + + + + + + + + + + + 

Fibroadenoma 

Skin + + + + 

Basal cell adenoma 

Fibroma X 

Keratoacanthoma 

Lipoma 

Squamous cell papilloma 

Trichoepithelioma 

Scrotum, fibroma X 

Subcutaneous tissue, sarcoma 

Musculoskeletal System 

Bone + + + + + + + + + + + + + + + + + + + + + + + + + 

Nervous System 

Brain + + + + + + + + + + + + + + + + + + + + + + + + + 

Astrocytoma NOS X 
Lesions in Male Rats 145 

TABLE A2 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Inhalation Study of Nickel Oxide: 1.25 mg/m 3 

(continued) 

Number of Days on Study 

6666666777777777777777777777 

7 7 8 8 9 9 9 0 0 0 0 1 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 

4 61 10 0 7 6 6 6 7 7 0 3 3 3 3 3 3 3 3 4 6 6 6 6 7 7 

Carcass ID Number 

2 3 3 3 2 2 2 2 2 2 3 2 2 2 2 2 2 2 2 2 3 2 2 2 3 3 3 3 Total 

8 1 12 7 9 8 6 7 8 0 7 6 6 6 7 8 8 9 9 1 9 6 6 0 0 0 1 Tissues/ 

0 6 0 5 0 9 7 5 3 9 3 9 4 1 8 8 5 8 3 6 4 1 2 6 5 7 9 3 Tumors 

Genital System 

Epididymis + + + + + + + + + + + + + + + + + + + + + + + ÷ + + + + 53 

Preputial gland + + + + + + + + + + + + + + + + + + + + + + + + + + + + 53 

Adenoma X 2 

Carcinoma 1 

Prostate + + + + + + + + + + + + + + + + + + .+ + + + + + + + + + 53 

Adenoma X 1 

Seminal vesicle + + + + + + + + + + + + + + + + + + + + + + + + + + + + 53 

Testes + + + + + + + + + + + + + + + + + + + + + + + + + + + + 53 

Bilateral, interstitial cell, adenoma X X X X X X X X X X X X X X X X X 27 

Interstitial cell, adenoma X X X X X X X X 16 

Hematopoietic System 

Bone marrow + + + + + + + + + + + + + + + + + + + + + + + + + + + + 53 

Lymph node + + + + + + + + 16 

Lymph node, bronchial + + + + + + + + + + + + + + + + + + + + + + + + + + + + 53 

Lymph node, mandibular + + + + M + + + + + + + + + + + + + M + + + + + + + M + 50 

Squamous cell carcinoma, metastatic 1 

Lymph node, mesenteric + + + + + + + + + + + + + + + + + + + + + + + + + + + + 53 

Lymph node, mediastinal + + + + + + + + + + + + + + + + + + + + M + + + + + + + 52 

Spleen + + + + + + + + + + + + + + + + + + + .+ + + + + + + + + 53 

Fibrosarcoma X 1 

Thymus + + + + + + + M + + + + + M + + + + + M + + + + + + + M 47 

Integumentary System 

Mammary gland + + + + + + + + + + + + + + + + + + + + + + + + + + + + 53 

Fibroadenoma X 1 

Skin + + + + + + + + + + 14 

Basal cell adenoma X 1 

Fibroma 1 

Keratoacanthoma X 1 

Lipoma X 1 

Squamous cell papilloma 1 

Trichoepithelioma X 1 

Scrotum, fibroma 1 

Subcutaneous tissue, sarcoma X 1 

Musculoskeletal System 

Bone + + + + + + + + + + + + + + + + + + + + + + + + + + + + 53 

Nervous System 

Brain + + + + + + + + + + + + + + + + + + + + + + + + + + + + 53 

Astrocytoma NOS 1 
146 Nickel Oxide, NTP TR 451 

TABLE A2 

Individual Animal Tumor Pathology of 

(continued) 

Male Rats in the 2-Year Inhalation Study of Nickel Oxide: 1.25 mg/m 3 

Number of Days on Study 

2345555555555566666666666 

0651244666778901 1 1 1222445 

2779516477088268899047770 

Carcass ID Number 

2333233223332222222332232 

6122912891018876969007928 

7143092378822 1 592354048 1 4 

Respiratory System 

Larynx 

Lung 

Alveolar/bronchiolar adenoma 

Alveolar/bronchiolar carcinoma 

Alvcolar/bronchiolar carcinoma, 

squamous differentiation 

Nose 

Trachea 

+++++ + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

+ + + ++ + + + + + + + + + + + + + + + + + + + + 

+ ++++ + + + + + + + + + + + + + + + + + + + + 

Special Senses System 

Ear 

Fibroma 

Eye 

+ 

X 

+ + + 

Urinary System 

Kidney 

Renal tubule, adenoma 

Transitional epithelium, carcinoma 

Urinary bladder 

+++++ + + + + + + + + + + + + + + + + + + + + 

X 

+++++ + + + + + + + + + + + + + + + + + + + + 

Systemic Lesions 

Multiple organs 

Leukemia mononuclear X -XX XX XX XX X X XX X 
Lesions in Male Rats 147 

TABLE A2 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Inhalation Study of Nickel Oxide: 1.25 mg/m 3 

(continued) 

Number of Days on Study 

6666666777777777777777777777 

7788999000013333333333333333 

4611007666770333333334666677 

Carcass ID Number 

23332222223222222222322233 33 Total 

81 127 9 8 6 7 8 0 7 6 6 6 7 8 8 9 9 1 9 6 6 0 0 0 1 Tissues/ 

0605097539394188583641265793 Tumors 

Respiratory System 

Larynx 

Lung 

Alveolar/bronchiolar adenoma 

Alveolar/bronchiolar carcinoma 

Alveolar/bronchiolar carcinoma, 

squamous differentiation 

Nose 

Trachea 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

X X X 

53 

53 

3 

X X 2 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 53 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 53 

Special Senses. System 

Ear 

Fibroma 

Eye 

Urinary System 

Kidney 

Renal tubule, adenoma 

Transitional epithelium, carcinoma 

Urinary bladder 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

X 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

53 

1 

1 

53 

Systemic Lesions 

Multiple organs 

Leukemia mononuclear 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 53 

XXXX XXXX X X X X 26 
148 Nickel Oxide, NTP TR 451 

TABLE A2 

Individual Animal Tumor Pathology of Mal.e Rats in the 2-Year Inhalation Study of Nickel Oxide: 2.5 mg/m 3 

Number of Days on Study 

444555555555555566666666 

667334456777789911222234 

785694535000834555345537 

Carcass ID Number 

444444444444444444443444 

01500440411343303434913-5 

521026289685089773044963 

Alimentary System 

Esophagus 

Intestine large, colon 

Mesothelioma malignant, metastatic 

Intestine large, rectum 

Intestine large, cecum 

Intestine small, duodenum 

Mesothelioma malignant, metastatic 

Intestine small, jejunum 

Mesothelioma malignant, metastatic 

Intestine small, ileum 

Liver 

Fibrous histiocytoma, metastatic 

Hepatoeellular carcinoma 

Hepatocellular adenoma 

Histiocytic sarcoma, metastatic, skin 

Mesothelioma malignant, metastatic 

Mesentery 

Mesothelioma malignant, metastatic, 

testes 

Pancreas 

Mesothelioma malignant, metastatic 

Salivary glands 

Stomach, forestomach 

Mesothelioma malignant, metastatic, 

testes 

Stomach, glandular 

Mesothelioma malignant, metastatic 

++++ + + + + + + + + + + + + + + + + + + + + 

++++ + + + + + + + + + + + + + + + + + + + + 

X 

++++ + + + + + + + + + + + + + + + + + + + + 

++++ + + + + + + + + + + + + + + + + + + + + 

++++ + + + + + + + + + + + + + + + + + + + + 

X 

++++ + + + + + + + + + + + + + + + + + + + + 

X 

+++ + + + + + + + + + + + + + + + + + + + + 

++++ + + + + + + + + + + + + + + + + + + + + 

X 

X 

X 

+ 

X 

+ +++ + + + + + + + + + + + + + + + + + + + + 

X 

++++ + + + + + + + + + + + + + + + + + + + + 

++++ + + + + + + + + + + + + + + + + + + + + 

X 

+ + + + ÷ +'+ -b + ÷ + ÷ + + + + + + + ÷ -b -b + + 

X 

Cardiovascular System 

Heart 

Carcinoma, metastatic, lung 

++++ + + + + + + + + + + + + + + .+ + + + + + 

Endocrine System 

Adrenal cortex 

Adrenal medulla 

Pheochmmocytoma malignant 

Pheochromocytoma benign 

Bilateral, pheochromocytoma benign 

Islets, pancreatic 

Adenoma 

Parathyroid gland 

Pituitary gland 

Pars distalis, adenoma 

Thyroid gland 

C-cell, adenoma 

Follicular cell, adenoma 

Follicular cell, carcinoma 

++++++++++++++++++++++.4-+ 

++++ + + + + + + + + + + + + + + + + + + + + 

X X 

X X X XXX X 

X X 

÷ + + ÷ + -b + + -b + + -b + + -~- + ÷ + + ÷ + -~- + + 

++++ + + + + + + + + + + + + + + + + + + +M 

+ + + -b + ÷ -k + + + ÷ ÷ ÷ + + + + + + ÷ + -b -b + 

X X X 

-b + -b + ÷ + + + ÷ ÷ + .+ + ÷ + + + + + + + + + + 

X 
Lesions in Male Rats 149 

TABLE A2 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Inhalation Study of Nickel Oxide: 2.5 mg/m 3 

(continued) 

Number of Days on Study 

6666666666777777777777777777 

5 6 6 6 6 7 7 7 7 9 0 0 0 1 1 2 3 3 3 3 3 3 3 3 3 3 3 3 

1 0 05 5 I 1 6 9 7 7 7 9 7 9 3 3 3 3 6 6 6 6 6 6 6 6 7 

Carcass ID Number 

4344444433444444444334444443 Total 

3 9 1 12 0 1 2 9 9 0 2 2 2 5 3 1 2 4 9 9 0 0 2 2 3 4 9 Tissues/ 

3 7 7 15 9 3 2 3 1 1 4 8 6 4 1 5 7 8 6 9 3 4 0 1 4 7 8 Tumors 

Alimentary System 

Esophagus 

Intestine large, colon 

Mesothelioma malignant, metastatic 

Intestine large, rectum 

Intestine large, cecum 

Intestine small, duodenum 

Mesothelioma malignant, metastatic 

Intestine small, jejunum 

Mesothelioma malignant, metastatic 

Intestine small, ileum 

Liver 

Fibrous histiocytoma, metastatic 

Hepatocellular carcinoma 

Hepatucellular adenoma 

Histiocytic sarcoma, metastatic, skin 

Mesothelioma malignant, metastatic 

Mesentery 

Mesothelioma malignant, metastatic, 

testes 

Pancreas 

Mesothelioma malignant, metastatic 

Salivary glands 

Stomach, forestomach 

Mesothelioma malignant, metastatic, 

testes 

Stomach, glandular 

Mesothelioma malignant, metastatic 

+ ++++ + + + + + + + + + + + + + + + + + + + + + + + 

+ ++++ + + + + + + + + + + + + + + + + + + + ÷ + + + 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

+++++ +++++++ +++ + ++M+ + + + ++ ++ + 

+++++ + + + + + + + + + + + + + +'+ + + + + + + + + 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + 

X 

X X 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + 

+ ++++ + + + + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

52 

52 

1 

52 

51 

52 

1 

52 

1 

51 

52 

1 

1 

2 

1 

1 

1 

1 

52 

1 

52 

52 

1 

52 

1 

Cardiovascular System 

Heart 

Carcinoma, metastatic, lung 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

X 

52 

1 

Endocrine System 

Adrenal cortex 

Adrenal medulla 

Pheochromocytoma malignant 

Pheochromocytoma benign 

Bilateral, pheochromocytoma benign 

Islets, pancreatic 

Adenoma 

Parathyroid gland 

Pituitary gland 

Pars distalis, adenoma 

Thyroid gland 

C-cell, adenoma 

Follicular cell, adenoma 

Follicular cell, carcinoma 

+ + +++ + + + + + + + + + + + + + + + + + + + + -F + + 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + 

X X X X 

X X X X X X X X X 

XX X XX XX X X X XXX X 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

X X 

+++++ +M+ + + + ++ + + + + + + + + +M+ + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

XX XX XX X X X 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

X X 

X 

52 

52 

6 

16 

16 

52 

2 

49 

52 

12 

52 

2 

1 

1 
150 Nickel Oxide, NTP TR 451 

TABLE A2 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Inhalation Study of Nickel Oxide: 2.5 mg/m 3 

(continued) 

Number of Days on Study 

444555555555555566666666 

6673 344567777899 1 1 222234 

785694535000834555345537 

Carcass ID Number 

444444444444444444443444 

015004404 1 1 3433034349 1 35 

521026289685089773044963 

General Body System 

Tissue NOS 

Basal cell carcinoma 

Carcinoma, metastatic, lung 

Fibrosarcoma 

+ 

X 

X 

Genital System 

Coagulating gland 

Epididymis 

Penis 

Preputial gland 

Adenoma 

Carcinoma 

Prostate 

Seminal vesicle 

Mesothelioma malignant, metastatic 

Testes 

Bilateral, interstitial cell, adenoma 

Interstitial cell, adenoma 

+ 

++++ + + + + + + + + + + + + + + + + + + + + 

++++M+ + + + + + + + + + + + + + + + + + + 

X X 

X 

++++ + + + + + + + + + + + + + + + + + + + + 

++++ + + + + + + + + + + + + + + + + + + + + 

X 

++++ + + + + + + + + + + + + + + + + + + + + 

X X XX X XX X X XX 

XX XX X X X XXX X 

Hematopoietic System 

Bone marrow 

Lymph node 

Lymph node, bronchial 

Lymph node, mandibular 

Lymph node, mcsenteric 

Lymph node, mcdiastinal 

Spleen 

Phcochromocytoma malignant, 

metastatic 

Thymus 

Carcinoma, metastatic, lung 

++++ + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + 

++++ + + + + + + ~- + + + + + + + + + + + + + 

+ +++ + + + + + + + + + + + + + + + + + + + + 

++++ + + + + + + + + + + + + + + + + + + + + 

++++ + + + + + + + + + + + + + + + + + + + +~ 

++++ + + + + + + + + + + + + + + + + + + + + 

X 

++++ + + + + + + + + + +M+ + + + + + + +M 

Integumentary System 

Mammary gland 

Skin 

Keratoacanthoma 

Papilloma 

Subcutaneous tissue, histiocytic sarcoma 

++++ + + + + + + + + + + + + + + + + + + + + 

+ + + + 

X 

Musculoskeletal System 

Bone 

Skeletal muscle 

Fibrous histiocytoma 

+÷++ + + + + + + + + + + + + + + + + ÷ + + + 

+ 

X 

Nervous System 

Brain 

Peripheral nerve 

Ganglion, paraganglioma benign 
Lesions in Male Rats 151 

TABLE A~ 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Inhalation Study of Nickel Oxide: 2.5 mg/m 3 

(continued) 

Number of Days on Study 

6666666666777777777777777777 

56666777790001 12333333333333 

10055 1 1 6 9 7 7 7 9 7 9 3 3 3 3 6 6 6 6 6 6 6 6 7 

Carcass ID Number 

43444444334444444443.34444443 Total 

391 12 0 1 2 9 9 0 2 2 2 5 3 1 2 4 9 9 0 0 2 2 3 4 9 Tissues/ 

37715 9 3 2 3 1 1 4 8 6 4 1 5 7 8 6 9 3 4 0 I 4 7 8 Tumors 

General Body System 

Tissue NOS + + 

Basal cell carcinoma 

Carcinoma, metastatic, lung X 

Fibrosarcoma 

Genital System 

Coagulating gland 

Epididymis 

Penis 

Preputial gland 

Adenoma 

Carcinoma 

Prostate 

Seminal vesicle 

Mesothelioma malignant, metastatic 

Testes 

Bilateral, interstitial cell, adenoma 

Interstitial cell, adenoma 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

+ 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

+++++++++++++++++++.4-++++++++ 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

XX XX XXX XX XXXXXX 

X XXX X X XX XX 

1 

52 

I 

51 

2 

1 

52 

52 

1 

52 

26 

21 

Hematopoietic System 

Bone marrow 

Lymph node 

Lymph node, bronchial 

Lymph node, mandibular 

Lymph node, mesenteric 

Lymph node, mediastinal 

Spleen 

Pheochromocytoma malignant, 

metastatic 

Thymus 

Carcinoma, metastatic, lung 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

++ + + + + 

++ +++ + + + + + + + + + + + + + + + + + + + + + + + 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

+++++++++ ++M++++ + ++M+ + + +++ ++ 

X 

52 

15 

52 

51 

51 

52 

52 

1 

48 

1 

Integumentary System 

Mammary gland + + + + + + + + + + + + + + + + + + + + + + + + + + + + 

Skin + + 

Keratoacanthoma X 

Papilloma X 

Subcutaneous tissue, histiocytic sarcoma 

52 

6 

1 

1 

1 

Musculoskeletal System 

Bone 

Skeletal muscle 

Fibrous histiocytoma 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + 52 

1 

1 

Nervous System 

Brain 

Peripheral nerve 

Ganglion, paragangliorna benign 

+ ++++ + + + + + + + + + + + + + + + + + + + + + + + 

+ 

X 

52 

1 

1 
152 Nickel Oxide, NTP TR 451 

TABLE A2 

Individual Animal Tumor Pathology of Male. Rats in the 2-Year Inhalation Study of Nickel Oxide: 2.5 mg/m 3 

(continued) 

Number of Days on Study 

4445 5 5 5 5 5 5 55 5 5 5 5 66666666 

66733445677778991 1222234 

785'694535000834555345537 

Carcass ID Number 

444444444444444444443444 

015004404 1 1 3433034349 1 35 

521026289685089773044963 

Respiratory System 

Larynx 

Lung 

Alveolar/bmnchiolar adenoma 

Alveolar/bronchiolar carcinoma 

Fibrous histiocytoma, metastatic 

Histiocytic sarcoma, metastatic, skin 

Pheochromocytoma malignant, 

metastatic 

Nose 

Trachea 

+ ÷ +÷ + + + + + + + + + + + + + q- ÷ + + + + 

-I- + + -I- + + + ++ + + + + + -I- + + + + + + -I- -I- + 

X 

X 

+ +++ + + + + + + + + + + + + + + + + + + + + 

++++ + + + + + + + + + + + + + + + + + + + + 

Special Senses System 

Eye + + + + 

Urinary System 

Kidney 

Histiocytic sarcoma, metastatic, skin 

Urinary bladder 

++++ + + + + + + + + + + + + + + + + + + + + 

X 

++++ + + + + + + + + + + + + + + + + + + + + 

Systemic Lesions 

Multiple organs 

Histiocytic sarcoma 

Leukemia mononuclear 

Mesothelioma malignant 

X 

XX XXXX XXX XXXXX X 

X 
Lesions in Male Rats 153 

TABLE A2 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Inhalation Study of Nickel Oxide: 2.5 mg/m 3 

(continued) 

Number of Days on Study 

6666666666777777777777777777 

566667 777 9000 1 1 2 3 3 3 3 3 3 3 3 3 3 3 3 

10055 1 1 6977797933336666666 67 

Carcass ID Number 

4344444433444444444334444443 Total 

391 120 1 29902225 3 1 24990022 3 4 9 Tissues/ 

37715 9 3 2 3 1 1 4 8 6 4 1 5 7 8 6 9 3 4 0 1 4 7 8 Tumors 

Respiratory System 

Larynx 

Lung 

Alveolar/bronchiolar adenoma 

Alveolar/bronchiolar carcinoma 

Fibrous histiocytoma, metastatic 

Histiocytic sarcoma, metastatic, skin 

Pheochromocytoma malignant, 

metastatic 

Nose 

Trachea 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + ~- + + + + 

X 

X X 

X 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

51 

52 

2 

2 

1 

1 

1 

52 

52 

Special Senses System 

Eye 

Urinary System 

Kidney 

Histiocytic sarcoma, metastatic, skin 

Urinary bladder 

+ ++++ + + + + + + + + + + + + + + + + + + + + + + + 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + 

52 

1 

52 

Systemic Lesions 

Multiple organs 

Histiocytic sar~coma 

Leukemia mononuctear 

Mesothelioma malignant 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

XXXXXXXXXX X XXXX XXXXX 

X 

52 

1 

35 

2 
154 Nickel Oxide, NTP TR 451 

TABLE A3 

Statistical Analysis of Primary Neoplasms in Male Rats in the 2-Year Inhalation Study of Nickel Oxide 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m ~ 2.5 mg/m 3 

Adrenal Medulla: Benign Pheochromocytoma 

Overall rate a 27/54 (50%) 24/52 (46%) 26/53 (49%) 32/52 (62%) 

Adjusted rate b 81.8 % 69.3 % 83.1% 93.8 % 

Terminal rate c 9/14 (64%) 6/15 (40%) 10/15 (67%) 10/12 (83%) 

First incidence (days) 475 570 519 553 

Life table test d P=0.054 P=0.302N P=0.472N P=0.123 

Logistic regression test d P=0.041 P=0.348N P=0.561N P=0.095 

Cochran-Armita~e test d P=0.094 

Fisher exact test- P = 0.420N P = 0.538N P = 0.159 

Adrenal Medulla: Malignant Pheochromocytoma 

Overall rate 0/54 (0%) 

Adjusted rate 0.0% 

Terminal rate 0/14 (0%) 

e First incidence (days) -- 

Life table test P<0.001 

Logistic regression test P < 0.001 

Cochran-Armitage test P < 0.001 

Fisher exact test 

Adrenal Medulla: Benign or Malignant Pheochromocytoma 

Overall rate 27/54 (50%) 

Adjusted rate 81.8% 

Terminal rate 9/14 (64%) 

First incidence (days) 475 

Life table test P=0.017 

Logistic regression test P=0.008 

Cochran-Arrnitage test P=0.024 

Fisher exact test 

Liver: Hepatocellular Adenoma 

Overall rate 3/54 (6%) 

Adjusted rate 11.2,% 

Terminal rate 1/14 (7%) 

First incidence (days) 475 

Life table test P=0.348N 

Logistic regression test P=0.280N 

Cochran-Armitage test P=0.271N 

Fisher exact test 

Liver: HepatoceHular Adenoma or Carcinoma 

Overall rate 5/54 (9%)" 

Adjusted rate 16.7% 

Terminal rate 1/14 (7%) 

First incidence (days) 475 

Life table test P=0.185N 

Logistic regression test P=0.134N 

Cochran-Armitage test P =0.129N 

Fisher exact test 

0/52 (0%) 1/53 (2%) 6/52 (12%) 

0.0% 2.8% 33.9% 

0/15 (0%) 0/15 (0%) 3/12 (25%) 

-- 619 467 

-- P=0.484 P=0.013 

-- P=0.499 P=0.015 

P=0.495 P=0.012 

P=0.420N P=0.538 P=0.053 

6/53 (11%) 3/53 (6%) 2/52 (4%) 

25.0% 8.9% 12.0% 

2/15 (13%) 0/15 (0%) 1/12 (8%) 

670 567 665 

P=0.283 P=0.634 P=0.555N 

P=0.245 P=0.660 P=0.517N 

P=0.235 P=0.652 P=0.518N 

7/53 (13%) 5/53 (9%) 2/52 (4%) 

30.8% 16.8% 12.0% 

3/15 (20%) 1/15 (7%) 1/12 (8%) 

670 564 665 

P=0.439 P=0.602 P=0.268N 

P=0.381 P=0.624 P=0.232N 

P=0.367 P=0.617 P=0.234N 

24/52 (46%) 27/53 (51%) 35/52 (67%) 

69.3% 83.6% 97.0% 

6/15 (40%) 10/15 (67%) 11/12 (92%) 

570 519 467 

P=0.302N P=0.537N P=0.055 

P=0.348N P=0.521 P=0.027 
Lesions in Male Rats 155 

TABLE A3 

Statistical Analysis of Primary Neoplasms in Male Rats in the 2-Year Inhalation Study of Nickel Oxide (continued) 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 

Lung: Alveolar/bronchiolar Adenoma 

Overall rate 0/54 (0%) 

Adjusted rate 0.0% 

Terminal rate 0,'14 (0%) 

First incidence (days) -- 

Life table test P=0.135 

Logistic regression test P =0.1~.0 

Cochran-Armitage test P=0.165 

Fisher exact test 

1/53 (2%) 3/53 (6%) 2/52 (4%) 

2.6% 20.0% 11.4% 

0/t5 (0%) 3/15 (20%) 1/12 (8%) 

623 733 (T) 633 

P=0.516 P=0.128 P=0.223 

P=0.484 P=0.128 P=0.219 

P=0.495 P=0.118 P =0.238 

Lung: Alveolar/bronchiolar Carcinoma 

Overall rate 0/54 (0%) 

Adjusted rate 0.0% 

Terminal rate 0/14 (0%) 

First incidence (days) -- 

Life table test P=0.070 

Logistic regression test P=0.092 

Cochran-Armitage test P=0.098 

Fisher exact test 

0/53 (0%) 3/53 (6%) 2/52 (4%) 

0.0% 9.6% 13.2% 

0/15 (0%) 0/15 (0%) 1/12 (8%) 

-- 567 697 

-- P=0.121 P=0.203 

-- P=0.118 P=0.206 

P=0.118 P=0.238 

Lung: 

Overall rate 1/54 (2%) 

Adjusted rate 7. 1% 

Terminal rate 1/14 (7%) 

First incidence (days) 733 (T) 

Life table test P=0.051 

Logistic regression test P=0.062 

Cochran-Armitage test P = 0.079 

Fisher exact test 

Alveolar/bronchiolar Adenoma or Carcinoma or Squamous Cell Carcinoma 

1/53 (2%) 6/53 (11%) 4/52 (8%) 

2.6% 27.7% 23.7% 

0/15 (0%) 3/15 (20%) 2/12 (17%) 

623 567 633 

P =0.743N P=0.065 P=0.143 

P =0.760N P=0.054 P=0.141 

P=0.748 P=0.053 P=0.170 

Pancreatic Islets: Adenoma 

Overall rate 2/54 (4%) 

Adjusted rate 11.8% 

Terminal rate 1/14 (7%) 

First incidence (days) 705 

Life table test P=0.591 

Logistic regression test P=0.596N 

Cochran-Armitage test P=0.541N 

Fisher exact test 

3/53 (6%) 2/53 (4%) 2/52 (4%) 

15.7% 11.1% 9.4% 

1/15 (7%) 1/15 (7%) 0/12 (0%) 

686 706 671 

P=0.525 P=0.662N P=0.636 

P=0.533 P=0.696N P=0.655 

P=0.491 P=0.684 P=0.677 

Lung: Alveolar/bronchiolar Adenoma or Carcinoma 

Overall rate 0/54 (0%) 1/53 (2%) 6/53 (11%) 4/52 (8%) 

Adjusted rate 0.0% 2.6% 27.7% 23.7% 

Terminal rate 0/14 (0%) 0/15 (0%) 3/15 (20%) 2/12 (17%) 

First incidence (days) -- 623 567 633 

Life table test P=0.020 P=0.516 P=0.020 P=0.050 

Logistic regression test P=0.026 P=0.484 P=0.016 P=0.048 

Cochran-Armitage test P=0.034 

Fisher exact test P = 0.495 P = 0.013 P = 0.054 
156 Nickel Oxide, NTP TR 451 

TABLE A3 

Statistical Analysis of Primary Neoplasms in Male Rats in the 2-Year Inhalation Study of Nickel Oxide (continued) 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m a 

Pancreatic Islets: Adenoma or Carcinoma 

Overall rate 3/54 (6%) 

Adjusted rate 18.6% 

Terminal rate 2/14 (14%) 

First incidence (days) 705 

Life table test P=0.446N 

Logistic regression test P=0.434N 

Cochran-Armitage test P=0.382N 

Fisher exact test 

Pituitary Gland (Pars Distalis): Adenoma 

Overall rate 24/53 (45%) 

Adjusted rate 75.2% 

Terminal rate 7/13 (54%) 

First incidence (days) 569 

Life table test P=0.052N 

Logistic regression test P=0.015N 

Cochran-Armitage test P=0.012N 

Fisher exact test 

Preputial Gland: Adenoma 

Overall rate 1/54 (2%) 

Adjusted rate 5.0% 

Terminal rate 0/14 (0%) 

First incidence (days) 705 

Life table test P=0.455 

Logistic regression test P=0.487 

Cochran-Armitage test P=0.485 

Fisher exact test 

Preputial Gland: Adenoma or Carcinoma 

Overall rate 1/54 (2%) 

Adjusted rate 5.0% 

Terminal rate 0/14 (0%) 

First incidence (days) 705 

Life table test P=0.262 

Logistic regression test P=0.283 

Cochran-Armitage test P=0.284 

Fisher exact test 

Skin: Fibroma 

Overall rate 3/54 (6%) 

Adjusted rate 9.3 % 

Terminal rate 0/14 (0%) 

First incidence (days) 566 

Life table test P=0.124N 

Logistic regression test P=0.111N 

Cochran-Armitage test P = 0.11 ON 

Fisher exact test 

4/53 (8%) 4/53 (8%) 2/52 (4%) 

19.8% 19.6% 9.4% 

1/15 (7%) 2/15 (13%) 0/12 (0%) 

686 606 671 

P=0.530 P=0.537 P=0.569N 

P=0.541 P=0.495 P=0.558N 

P=0.489 P=0.489 P=0.518N 

18/52 (35%) 16/52 (31%) 12/52 (23%) 

67.3% 56.0% 47.8% 

8/15 (53%) 5/14 (36%) 3/12 (25%) 

519 367 539 

P=0.127N P=0.121N P=0.052N 

P=0.124N P=0.093N P=0.015N 

P=0.180N P=0.092N P=0.014N 

3/53 (6%) 2/53 (4%) 2/51 (4%) 

11.2% 6.4% 4.7% 

1/15 (7%) 0/15 (0%) 0/12 (0%) ' 

595 578 570 

P=0.319 P=0.496 P=0.472 

P=0.303 P=0.492 P=0.471 

P=0.302 P=0.493 P=0.478 

3/53 (6%) 2/53 (4%) 3/51 (6%) 

11.2% 6.4% 6.6% 

1/15 (7%) 0/15 (0%) 0/12 (0%) 

595 578 475 

P=0.319 P=0.496 P=0.282 

P=0.303 P=0.492 P=0.249 

P=0.302 P=0.493 P=0.288 

1/53 (2%) 2/53 (4%) 0/52 (0%) 

2.4% 4.1% 0.0% 

0/15 (0%) 0/15 (0%) 0/12 (0%) 

572 525 -- 

P=0.310N P=0.519N P=0.150N 

P=0.337N P=0.498N P=0.127N 

P=0.316N P=0.509N P=0.129N 
Lesions in Male Rats 157 

TABLE A3 

Statistical Analysis of Primary Neoplasms in Male Rats in the 2-Year Inhalation Study of Nickel Oxide (continued) 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 

Skin: Papilloma, Squamous Cell Papilloma, Keratoacanthoma, Trichoepithelioma, Basal Cell Adenoma, 

or Squamous Cell Carcinoma 

Overall rate 3/54 (6%) 2/53 (4%) 4/53 (8%) 2/52 (4%) 

Adjusted rate 16.1% 6.7% 19.5% 16.7% 

Terminal rate 2/14 (14%) 0/15 (0%) 1/15 (7%) 2/12 (17%) 

First incidence (days) 569 570 690 733 (T) 

Life table test P=0,544N P=0.489N P=0.518 P=0.566N 

Logistic regression test P=0.532N P=0,503N P=0.490 P=0,552N 

Cochran-Armitage test P=0.494N 

Fisher exact test P=0.509N P=0.489 P=0.518N 

Testes: Adenoma 

Overall rate 40/54 (74%) 

Adjusted rate 94.9% 

Terminal rate 12/14 (86%) 

First incidence (days) 509 

Life table test P=0.063 

Logistic regression test P=0,024 

Cochran-Armitage test P=0,039 

Fisher exact test 

46/53 (87%) 43/53 (81%) 47/52 (90%) 

100.0% 100.0% 100.0% 

15/15 (100%) 15/15 (100%) 12/12 (100%) 

466 457 467 

P=0.373 P=0.403 P=0.077 

P=0.091 P=0.199 P =0.022 

P=0.078 P=0.260 P=0.025 

Thyroid Gland (C-cell): Adenoma 

Overall rate 6/54 (I 1%) 

Adjusted rate 28.1% 

Terminal rate. 2/14 (14%) 

First incidence (days) 475 

Life table test P=0.143N 

Logistic regression test P=0.120N 

Cochran-Armitage test P=0.104N 

Fisher exact test 

5/53 (9%) 4/52 (8%) 2/52 (4%) 

18,1% 24.7% 13.2% 

0/15 (0%) 3/15 (20%) 1/12 (8%) 

647 717 697 

P=0,450N P =0,339N P=0.195N 

P=0.491N P=0.382N P=0.161N 

P=0,513N P=0,395N P=0.148N 

Thyroid Gland (C-cell): Adenoma or Carcinoma 

Overall rate 7/54 (13%) 

Adjusted rate 32.6% 

Terminal rate 2/14 (14%) 

First incidence (days) 475 

Life table test P=0.108N 

Logistic regression test P=0.087N 

Cochran-Armitage test P=0.075N 

Fisher exact test 

5/53 (9%) 5/52 (10%) 2/52 (4%) 

18.1% 26.6% 13.2% 

0/15 (0%) 3/15 (20%) 1/12 (8%) 

647 606 697 

P=0.334N P=0.350N P =0.128N 

P=0.367N P=0.398N P=0.102N 

P=0.394N P =0.407N P=0.090N 

Thyroid Gland (Follicular Cell): Adenoma 

Overall rate 1/54 (2%) 

Adjusted rate 4.5 % 

Terminal rate 0/14 (0%) 

First incidence (days) 699 

Life table test P=0.529N 

Logistic regression test P=0,509N 

Cochran-Armitage test P=0.485N 

Fisher exact test 

3•53 (6%) 2/52 (4%) 1/52 (2%) 

9.8% 13.3% 3.7% 

0/15 (0%) 2/15 (13%) 0/12 (0%) 

629 733 (T) 660 

P=0.349 P=0.511 P=0.730 

P=0.306 P =0,505 P=0.746 

P=0,302 P=0.486 P=0,743 
158 Nickel Oxide, NTP TR 451 

TABLE A3 

Statistical Analysis of Primary Neoplasms in Male Rats in the 2-Year Inhalation Study of Nickel Oxide (continued) 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m ~ 

Thyroid Gland (Follicular Cell): Adenoma or Carcinoma 

Overall rate 

Adjusted rate 

Terminal rate 

First incidence (days) 

Life table test 

. 

Logistic regression test 

Cochran-Armitage test 

Fisher exact test 

2/54 (4%) 3/53 (6%) 2/52 (4%) 2/52 (4%) 

9.8% 9.8% 13.3% 7.0% 

0/14 (0%) 0/15 (0%) 2/15 (13%) 0/12 (0%) 

699 629 733 (T) 647 

P=0.590N P=0.541 P=0.690N P =0.648 

P=0.569N P=0.507 P=0.696N P=0.668 

P=0.542N 

All Organs: Mononuclear Cell Leukemia 

Overall rate 

Adjusted rate 

Terminal rate 

First incidence (days) 

Life table test 

Logistic regression test 

Cochran-Armitage test 

Fisher exact test 

P=0.491 P=0.677 P=0.677 

All Organs: Benign Neoplasms 

Overall rate 

Adjusted rate 

Terminal rate 

First incidence (days) 

Life table test 

Logistic regression test 

Cochran-Armitage test 

Fisher exact test 

31/54 (57%) 32/53 (60%) 26/53 (49%) 35/52 (67%) 

77.2 % 73.3 % 63.1% 90.1% 

7/14 (50%) 5/15 (33%) 3/15 (20%) 9/12 (75%) 

475 503 202 536 

P=0.155 P=0.521N P=0.309N P=0.173 

P=0.211 P=0.419 P=0.245N P=0.212 

P=0.207 

All Organs: Malignant Neoplasms 

Overall rate 

Adjusted rate 

Terminal rate 

First incidence (days) 

Life table test 

Logistic regression test 

Cochran-Armitage test 

Fisher exact test 

P=0.454 P=0.251N P=0.198 

53/54 (98%) 51/53 (96%) 52/53 (98%) 52/52 (100%) 

100.0% 100.0% 100.0% 100.0% 

14/14 (100%) 15/15 (100%) 15/15 (100%) 12/12 (I00%) 

187 466 367 467 

P=0.227 P=0.337N P=0.507N P=0.320 

P=0.303 P=0.390N P=0.777 P=0.530 

P=0.255 

P=0.493N P=0.748N P=0.509 

37/54 (69%) 38/53 (72%) 35/53 (66%) 43/52 (83%) 

84.1%, 80.1% 77.9% 97.3% 

8/14 (57%) 6/15 (40%) 6/15 (40%) 11/12 (92%) 

475 466 202 467 

P = 0.089 P =0.504N P = 0.465N P=0.116 

P=0.071 P=0.434 P=0.472N P=0.071 

P~0.068 

P=0.441 P=0.473N P=0.070 
Lesions in Male Rats 159 

TABLE A3 

Statistical Analysis of Primary Neoplasms in Male Rats in the 2-Year Inhalation Study of Nickel Oxide (continued) 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m ~ 

All Organs: Benign or Malignant Neoplasms 

Overall rate 

Adjusted rate 

Terminal rate 

First incidence (days) 

Life table test 

Logistic regression test 

Cochran-Armitage test 

Fisher exact test 

54/54 (100%) 53/53 (100%) 53/53 (100%) 52/52 (100%) 

100.0% 100.0% 100.0% 100.0% 

14/14 (100%) 15/15 (100%) 15115 (100%) 12/12 (100%) 

187 466 202 467 

P=0.281 P=0.386N P=0.509N P=0.359 

f 

.... 

P= 1.000N P= 1 .IX)0N P= 1.000N 

(T)Terminal sacrifice 

a Number of neoplasm-bearing animals/number of animals examined. 

b 

c 

d 

Denominator is number of animals examined microscopically for adrenal gland, liver, 

lung, pancreatic islets, pituitary gland, preputial gland, testes, and thyroid gland; for other tissues, denominator is number of animals necropsied. 

Kaplan-Meier estimated neoplasm incidence at the end of the study after adjustment for intercurrent mortality 

Observed incidence at terminal kill 

Beneath the cbntrol incidence are the P values associated with the trend test. Beneath the ekposed group incidence are the P values corresponding to 

pairwise comparisons between the controls and that exposed group. The life table test regards neoplasms in animals dying prior to terminal kill as being 

(directly or indirectly) the cause of death. The logistic regression test regards these lesions as nonfatal. The Cochran-Armitage and Fisher exact tests 

compare directly the overall incidence rates. For all tests, a negative trend or a lower incidence in an exposure group is indicated by N. 

Not applicable; no neoplasms in animal group 

Value of statistic cannot be computed. 
160 Nickel Oxide, NTP TR 451 

TABLE A4a 

Historical Incidence of Lung Neoplasms in Untreated Male F344/N Rats a 

Incidence in Controls 

Study Alveolar/bronchiolar Alveolar/bronchiolar 

Adenoma Carcinoma 

Squamous Cell 

Carcinoma 

Alveolar/bronchiolar 

Adenoma or Carcinoma 

or Squamous Cell 

Carcinoma 

Historical Incidence at Lovelace Inhalation Toxicology Research Institute 

Nickel Oxide 0/54 0/54 1/54 1/54 

Nickel Subsulfide 0/53 0/53 0/53 0/53 

Nickel Sulfate Hexahydrate 0/54 1/54 1/54 2/54 

Talc b 0/49 0/49 0/49 0/49 

Overall Historical Incidence in Inhalation Studies 

Total 17/703 (2.4%) 6/703 (0.9%) 4/703 (0.6%) 27/703 (3.8%) 

Standard deviation 3.5% 1.0% 0.9% 3.8% 

Range 0%-10% 0%-2% 0%-2% 0%-10% 

Overall Historical Incidence in Feed Studies 

Total 28/1,200 (2.3%) 11/1,200 (0.9%) 

Standard deviation 2.0 % 1.2 % 

Range 0%-6% 0%-4% 

0/1,200 (0%) 39/1,200 (3.3%) 

2.0% 

0%-8% 

a Data as of 17 June 1994 

b Results of lifetime study; others are 2-year studies 
Lesions in Male Rats 161 

TABLE A4b 

Historical Incidence of Pheochromocytomas of the Adrenal Medulla in Untreated Male F344/N Rats a 

Incidence in Controls 

Study Benign Complex Malignant NOS Benign, Complex, 

Malignant or NOS 

Historical Incidence at Lovelace Inhalation Toxicology Research Institute b 

Nickel Oxide 27/54 0/54 0/54 0/54 27/54 

Nickel Subsulfide 13/53 1/53 0/53 0/53 14/53 

Nickel Sulfate Hexahydrate 16/54 0/54 0/54 0/54 16/54 

Overall Historical Incidence in Inhalation Studies 

Total 163/623 (26.2%) 2/623 (0.3%) 11/623 (1.8%) 7/623 (1.1%) 

Standard deviation 13.1% 0.8% 2.9% 3.9% 

Range 0%-50% 0%-2% 0%-10% 0%-14% 

176/623 (28.3 %) 

12.0% 

8%-50% 

Overall Historical Incidence in Feed Studies 

Total 379/1,182 (32.1%) 2/1,182 (0.2%) 33/1,182 (2.8%) 

Standard deviation 11.7 % 0.6 % 3.2 % 

Range 10%-63 % 0%-2% 0%-12% 

0/1,182 (0%) 400/1,182 (33.8%) 

10.9% 

14%-63% 

a Data as of 17 June 1994 

b Talc excluded because it was not a 2-year study. 
162 Nickel Oxide, NTP TR 451 

TABLE A5 

Summary of the Incidence of Nonneoplastic Lesions in Male Rats in the 2-Year Inhalation Study of Nickel Oxide a 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 

Disposition Summary 

Animals initially in study 65 65 65 

7-Month interim evaluation 6 7 7 

15-Month interim evaluation 5 5 5 

Early deaths 

Moribund 39 35 32 

Natural deaths 1 3 6 

Survivors 

Died last week of study 1 

Terminal sacrifice 14 15 14 

Missexed 

Animals examined microscopically 

65 

7 

5 

36 

4 

1 

11 

1 

65 65 65 64 

7-Month Interim Evaluation 

Alimentary System 

Liver (1) 

Hepatodiaphragmatic nodule 1 (100%) 

Hematopoietic System 

Lymph node 

Pigmentation 

Lymph node, bronchial 

Congestion, chronic 

Hyperplasia 

Hyperplasia, lymphoid 

Pigmentation 

Lymph node, mediastinal 

Congestion 

Hyperplasia, lymphoid 

Pigmentation 

(I) 

I 

(6) (7) (7) 

i (17%) 

1 (17%) 7 

7 

(6) (6) (6) 

1 (17%) 

(lOO%) 

(1oo%) 

(100%) 

(50%) 

(67 %) 

(7) 

[ (14%) 

4 (57%) 

7 (100%) 

(6) 

3 (50%) 

Respiratory System 

Lung 

Inflammation, chronic 

Alveolus, pigmentation 

(6) (7) 

3 (50%) 

6 (86%) 

(7) 

7 (lOO%) 

7 (lOO%) 

(7) 

7 (100%) 

6 (86%) 

Urinary System 

Urinary bladder (3) 

Calculus, microscopic observation only 3 (100%) 

(3) 

3 (lOO%) 

(5) 

5 (lOO%) 

(4) 

4 (100%) 

a Number of animals examined microscopically at the Site and the number of animals with lesion 
Lesions in Male Rats 163 

TABLE A5 

Summary of the Incidence of Nonneoplastic Lesions in Male Rats in the 2-Year Inhalation Study of Nickel Oxide 

(continued) 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 

7-Month Interim Evaluation (continued) 

Systems Examined With No Lesions Observed 

Cardiovascular System 

Endocrine System 

General Body System 

Genital System 

Integumentary System 

Museuloskeletal System 

Nervous System 

Special Senses System 

15-Month Interim Evaluation 

Alimentary System 

Liver 

Eosinophilic focus 

Hcpatoeyte, hyperplasia 

(5) (5) (5) 

1 (20%) 

(5) 

1 (20%) 

Endocrine System 

Adrenal medulla 

Hyperplasia 

Pituitary gland 

Hyperplasia 

(5) 

(5) 

(5) 

(5) 

(5) 

1 (20%) 

(5) 

(5) 

2 (40%) 

(5) 

1 (20%) 

Genital System 

Preputial gland 

Inflammation, suppurative 

Duct, ectasia 

Testes 

Interstitial cell, hyperplasia 

(5) 

(5) 

1 (20%) 

(5) 

1 (20%) 

(5) 

1 (20%) 

(5) 

(5) 

3 (60%) 

(5) 

1 (20%) 

(5) 

Hematopoietic System 

Bone marrow 

Hyperplasia 

Lymph node, bronchial 

Hyperplasia, lymphoid 

Pigmentation 

Lymph node, mediastinat 

Hyperplasia, lymphoid 

Pigmentation 

(5) 

(5) 

(5) 

(5) 

(5) 

5 (loo%) 

(5) 

3 (60%) 

(5) 

(5) 

4 (80%) 

5 (tO0%) 

(5) 

2 (40%) 

4 (80%) 

(5) 

t (20%) 

(5) 

4 (80%) 

5 (lOO%) 

(4) 

1 (25%) 

40oo%) 
164 Nickel Oxide, NIP TR 451 

TABLE A5 

Summary of the Incidence of Nonneoplastic Lesions in Male Rats in the 2-Year Inhalation Study of Nickel Oxide 

(continued) 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 

15-Month Interim Evaluation (continued) 

Respiratory System 

Lung (5) 

Inflammation, chronic 4 (80%) 

Alveolus, pigmentation 

Nose (5) 

Respiratory epithelium, inflammation, focal, 

suppurative 1 (20%) 

(5) (5) (5) 

5 000%) 5 (100%) 5 (100%) 

5 (100%) 5 (100%) 5 (100%) 

(5) (5) (5) 

Special Senses System 

Eye (3) 

Cataract 1 (33%) 

Cornea, edema 1 (33%) 

Retina, degeneration 1 (33 %) 

Vitreous, inflammation, chronic 1 (33%) 

Urinary System 

Kidney (5) 

Nephropathy 5 (100%) 

Urinary bladder (5) 

Calculus, microscopic observation only 3 (60 %) 

(5) (5) (5) 

4 (80%) 5 (100%) 4 (80%) 

(5) (5) (5) 

1 (20%) 1 (20%) 

Systems Examined With No Lesions Observed 

Cardiovascular System 

General Body System 

Integumentary System 

Musculoskeletal System 

Nervous System 

2- Year Study 

Alimentary System 

Intestine large, colon (54) (53) (53) 

Erosion 1 (2%) 

Parasite metazoan 1 (2%) 1 (2%) 

Intestine large, rectum (54) (53) (52) 

Parasite metazoan 1 (2%) 1 (2%) 

Intestine large, cecum (54) (53) (52) 

Inflammation, chronic active 1 (2%) 

Inflammation, suppurative 1 (2%) 

Necrosis 1 (2%) 

Parasite metazoan 1 (2 %) 

Ulcer 1 (2%) 

Intestine small, jejunum (54) (53) (53) 

Inflammation, chronic 1 (2%) 

Inflammation, chronic active 

Inflammation, suppurative 1 (2%) 

(52) 

I (2%) 

(52) 

(51) 

(52) 

1 (2%) 
Lesions in Male Rats 165 

TABLE A5 

Summary of the Incidence of Nonneoplastic Lesions in Male Rats in the 2-Year Inhalation Study of Nickel Oxide 

(continued) 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 

2-Year Study (continued) 

Alimentary System (continued) 

Liver (54) (53) (53) (52) 

Angiectasis 1 (2%) 

Basophilic focus 21 (39%) 15 (28%) 22 (42%) 20 (38%) 

Clear cell focus 1 (2%) 1 (2%) 

Congestion I (2%) 4 (8%) 

Degeneration, cystic 16 (30%) 20 (38%) 27 (51%) 28 (54%) 

Developmental malformation 1 (2%) 1 (2%) 

Eosinophilic focus 3 (6%) 4 (8%) 5 (9%) 7 (13%) 

Fatty change 13 (24%) 15 (28%) 20 (38%) 11 (21%) 

Hemorrhage 1 (2%) 

Hepatodiaphragmatic nodule 4 (7%) 1 (2%) 2 (4%) 4 (8%) 

Infarct 1 (2 %) 

Inflammation, chronic active 1 (2%) 

Inflammation, suppurative 1 (2%) 

Mixed cell focus 1 (2%) 

Pigmentation, bile 1 (2%) 1 (2%) 

Thrombosis 1 (2%) 1 (2%) 1 (2%) 1 (2%) 

Thrombosis, multiple 2 (4%) 

Bile duct, hyperplasia 17 (31%) 20 (38%) 18 (34%) 25 (48%) 

Hepatocyte, hyperplasia 8 (15%) 14 (26%) 9 (17%) 10 (19%) 

Hepatocyte, necrosis 8 (15%) 14 (26%) 4 (8%) 10 (19%) 

Portal vein,, thrombosis 1 (2%) 

Pancreas (54) (53) (53) t52) 

Atrophy 1 (2%) 1 (2%) 

Congestion 1 (2%) 

Fibrosis 1 (2%) 

Acinus, atrophy 5 (9%) 1 (2%) 1 (2%) 2 (4%) 

Acinus, fibrosis 1 (2%) 

Acinus, hyperplasia 2 (4%) 1 (2%) 

Stomach, forestomach (54) (53) (53) (52) 

Edema 3 (6%) 

Hyperkeratosis 1 (2%) 6 (11%) 1 (2%) 

Inflammation, acute 1 (2%) 

Inflammation, chronic 1 (2%) 3 (6%) 

Inflammation, chronic active 1 (2%) 

Inflammation, suppurative 1 (2%) 

Ulcer 1 (2%) 3 (6%) 3 (6%) 

Ulcer, multiple 2 (4%) 

Stomach, glandular (54) (53) (53) (52) 

Erosion 1 (2%) t (2%) 

Inflammation, chronic 1 (2%) 1 (2%) 

Inflammation, chronic active ! (2%) 

Inflammation, suppurative 1 (2%) I (2%) 1 (2%) 

Pigmentation 1 (2%) 

Ulcer 1 (2%) 
166 ~ Nickel Oxide, NTP TR 451 

TABLE A5 

Summary of the Incidence of Nonneoplastic Lesions in Male Rats in the 2-Year Inhalation Study of Nickel Oxide 

(continued) 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 

2-Year Study (continued) 

Cardiovascular System 

Blood vessel 

Aorta, mineralization 

Heart 

Fibrosis 

Infarct 

Inflammation, chronic 

Inflammation, suppurative 

Atrium, congestion 

Atrium, thrombosis 

Epicardium, degeneration 

Myocardium, mineralization 

Ventricle, fibrosis 

Ventricle, inflammation, chronic 

Ventricle, mineralization 

Ventricle, thrombosis 

(2) (1) 

2 (100%) 1 (100%) 

(54) (53) (53) 

1 (2%) 

2 (4%) 

4 (7%) 6 (11%) 

1 (2%) 

1 (2%) 

1 (2%) 

4 (8%) 

(52) 

1 

1 

1 

4 

(2%) 

(2%) 

(2%) 

(8%) 

(2%) 

(2%) 

(2%) 

(2%) 

Endocrine System 

Adrenal cortex (54) (53) (53) (52) 

Angiectasis 2 (4%) 

Degeneration, fatty 2 (4%) 1 (2%) 6 (11%) 3 (6%) 

Adrenal medulla (54) (52) (53) (52) 

Cyst 1 (2%) 

Degeneration, fatty 1 (2%) 

Hyperplasia 25 (46%) 27 (52%) 26 (49%) 24 (46%) 

Islets, pancreatic (54) (53) (53) (52) 

Hyperplasia 3 (6%) 2 (4%) 1 (2%) 

Parathyroid gland (50) (50) (49) (49) 

Hyperplasia 2 (4%) 2 (4%) 2 (4%) 

Pituitary gland (53) (52) (52) (52) 

Angiectasis 2 (4%) 3 (6%) 

Hyperplasia 1 (2%) 

Pars distalis, angiectasis 1 (2%) 3 (6%) 

Pars distalis, cyst 2 (4%) 2 (4%) 

Pars distalis, hyperplasia 4 (8%) 3 (6%) 6 (12%) 11 (21%) 

Pars distalis, necrosis 1 (2%) 

Pars distalis, pigmentation 1 (2 %) 

Thyroid gland (54) (53) (52) (52) 

Hyperplasia, cystic 1 (2%) 

Infiltration cellular, lymphocyte 1 (2 %) 

C-cell, hyperplasia 1 (2%) 1 (2%) 2 (4%) 2 (4%) 

General Body System 

Tissue NOS 

Developmental malformation 

Oral, inflammation, chronic active 

(3) (2) (2) (4) 

1 (50%) 

1 (33%) 
Lesions in Male Rats 167 

TABLE A5 

Summary of the Incidence of Nonneoplastic Lesions in Male Rats in the 2-Year Inhalation Study of Nickel Oxide 

(continued) 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 

2-Year Study (continued) 

Genital System 

Coagulating gland (4) 

Inflammation, chronic 1 (25%) 

Inflammation, suppurative 2 (50%) 

Epididymis (54) (53) (53) 

Spermatoccle 1 (2%) 2 (4%) 

Preputial gland (54) (53) (53) 

Ectasia 2 (4%) 3 (6%) 4 (8%) 

Hyperplasia, glandular 

Inflammation, suppurative 3 (6%) 1 (2%) 

Bilateral, ectasia 1 (2%) 

Prostate (53) (53) (53) 

Hyperplasia 1 (2%) 

Inflammation, chronic 3 (6%) 3 (6%) 

Inflammation, chronic active 1 (2%) 1 (2%) 

Inflammation, suppurative 3 (6%) 1 (2%) 4 (8%) 

Seminal vesicle (54) (53) (53) 

Atrophy 3 (6%) 3 (6%) 

Ectasia 1 (2%) 1 (2%) 

Inflammation, suppurative 2 (4%) 

Testes (54) (53) (53) 

Atrophy 11 (20%) 7 (13%) 7 (13%) 

Hemorrhage 1 (2%) 

Bilateral, atrophy 1 (2%) 2 (4%) 

Interstitial cell, hyperplasia 7 (13%) 3 (6%) 

(I) 

1 (100%) 

(52) 

(51) 

1 (2%) 

1 (2%) 

2 (4%) 

(52) 

1 (2%) 

1 (2%) 

(52) 

(52) 

10 (19%) 

Hematopoietie System 

Bone marrow (54) (53) (53) 

Fibrosis 7 (13%) 4 (8%) 5 (9%) 

Hyperplasia 24 (44%) 35 (66%) 19 (36%) 

Lymph node (16) (19) (16) 

Hyperplasia, macrophage 

Pigmentation 4 (21%) 

Iliac, congestion 2 (11%) 

Iliac, ectasia 1 (6%) 

lliac, hyperplasia, lymphoid 1 (6%) 1 (5%) 1 (6%) 

Iliac, pigmentation 1 (6%) 

Pancreatic, congestion 1 (5%) 

Pancreatic, hyperplasia, lymphoid 1 (6%) 

Renal, congestion 2 (11%) 1 (6%) 

Renal, edema 

Renal, hyperplasia, lymphoid 1 (6%) 2 (I1%) 1 (6%) 

Renal, pigmentation 3 (16%) 

Lymph node, bronchial (52) (51) (53) 

Congestion 1 (2%) I (2%) 

Edema 1 (2%) 

Hyperplasia, lymphoid 7 (14%) 10 (19%) 

Hyperplasia, macrophage 1 (2%) 

Pigmentation 45 (88%) 51 (96%) 

(52) 

4 (8%) 

35 (67%) 

(15) 

1 (7%) 

1 (7%) 

1 (7%) 

2 (13%) 

(52) 

3 (6%) 

1 (2%) 

18 (35%) 

51 (98%) 
168 Nickel Oxide, NTP TR 451 

TABLE A5 

Summary of the Incidence of Nonneoplastic. Lesions in Male Rats in the 2-Year Inhalation Study of Nickel Oxide 

(continued) 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m ~ 

2-Year Study (continued) 

Hematopoietic System (continued) 

Lymph node, mandibular (49) (51) (50) (51) 

Hyperplasia, lymphoid 5 (10%) 4 (8%) 6 (12%) 3 (6%) 

Lymph node, mesenteric (54) (53) (53) (51) 

Congestion 2 (4%) 

Edema 1 (2%) 

Hyperplasia 1 (2%) 

Hyperplasia, lymphoid 1 (2%) 2 (4%) 1 (2%) 

Lymph node, mediastinal (47) (52) (52) (52) 

Congestion 1 (2%) 2 (4%) 3 (6%) 

Ectasia 1 (2%) 1 (2%) 

Hyperplasia, lymphoid 5 (11% ) 8 ( 15 %) 11 (21% ) 18 (35 %) 

Hyperplasia, plasma cell 3 (6%) 2 (4%) 1 (2%) 

Pigmentation 33 (63%) 43 (83%) 50 (96%) 

Spleen (54) (53) (53) (52) 

Congestion 1 (2%) 

Developmental malformation 1 (2%) 1 (2%) 

Fibrosis 11 (20%) 7 (13%) 15 (28%) 10 (19%) 

Infarct 4 (7%) 6 (11%) 3 (6%) 2 (4%) 

Necrosis 1 (2%) 1 (2%) 

Capsule, fibrosis 1 (2%) 

Thymus (44) (49) (47) (48) 

Congestion 1 (2%) 

Integumentary System 

Mammary gland (54) 

Ectasia 

Hyperplasia 1 (2%) 

Duct, ectasia 

Skin ( 13 ) 

Alopecia 

Cyst epithelial inclusion 2 (15 %) 

Hyperkeratosis 1 (8%) 

Necrosis 

Pigmentation 1 (8%) 

Epidermis, hyperplasia 

(53) (53) (52) 

1 (2%) 

1 (2%) 

(4) (14) (6) 

1 (7%) 

2 (50%) 2 (14%) 1 (17%) 

1 (7%) 

I (7%) 

1 (7%) 

1 (17%) 

Musculoskeletal System 

Bone 

Hyperostosis 

Femur, hyperostosis 

(54) (53) (53) (52) 

1 (2%) 2 (4%) 2 (4%) 

2 (4%) 4 (8%) 

Nervous System 

Brain 

Hemorrhage 

Cerebellum, compression 

Cerebellum, hemorrhage 

Cerebellum, ventricle, dilatation 

(54) (53) (53) (52) 

1 (2%) 

1 (2%) 1 (2%) 1 (2%) 

2 (4%) 3 (6%) 

1 (2%) 
Lesions in Male Rats 169 

TABLE A5 

Summary of the Incidence of Nonneoplastic Lesions in Male Rats in the 2-Year Inhalation Study of Nickel Oxide 

(continued) 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m 3 2.5 mg!m 3 

2-Year Study (continued) 

Nervous System (continued) 

Brain (continued) (54) (53) (53) 

Cerebmm, compression 5 (9%) 7 (13%) 

Cerebrum, degeneration 1 (2%) 

Cerebrum, hemorrhage 1 (2%) 1 (2%) 

Cerebrum, necrosis I (2%) 

Cerebrum, ventricle, dilatation 2 (4%) 

Hypothalamus, compression 8 (15%) 1 (2%) 

Pons, compression 2 (4%) 

Thalamus, degeneration 1 (2 %) 

Ventricle, dilatation 2 (4%) 1 (2%) 1 (2%) 

(52) 

5 (I0%) 

1 (2%) 

3 (6%) 

Respiratory System 

Larynx (52) (52) (53) (51) 

Inflammation, chronic 2 (4%) 1 (2%) 

Inflammation, chronic active 2 (4%) 

Inflammation, suppurative 1 (2%) 

Lung (54) (53) (53) (52) 

Congestion 1 (2%) 

Cyst 1 (2%) 

Hemorrhage 1 (2%) 1 (2%) 2 (4%) 

Inflammation, chronic 28 (52%) 53 (100%) 53 (100%) 52 (100%) 

Mineralization 1 (2%) 

Alveolar epithelium, hyperplasia, atypical 4 (8%) 3 (6%) 

Alveolar epithelium, hyperplasia, focal 2 (4%) 1 (2%) 

Alveolar epithelium, metaplasia, squamous 1 (2%) 

Alveolus, pigmentation 1 (2%) 53 (100%) 53 (100%) 52 (100%) 

Nose (54) (53) (53) (52) 

Inflammation, chronic active 1 (2%) 2 (4%) 2 (4%) 5 (10%) 

Inflammation, suppurative 5 (9%) 2 (4%) 3 (6%) 2 (4%) 

Trachea (53) (53) (53) (52) 

Inflammation, focal, suppurative 1 (2 %) 

Special Senses System 

Eye (9) • (5) 

Cataract 4 (44%) 3 (60%) 

Anterior chamber, cornea, inflammation, 

suppurative 1 (11%) 

Bilateral, cornea, edema I (11%) 

Cornea, edema 1 (11%) 

Cornea, inflammation, suppurative 1 (20%) 

Lids, inflammation, chronic active 1 (20%) 

Sclera, metaplasia, osseous 1 (11%) 

(3) 

1 (33%) 

(5) 

3 (60%) 
170 Nickel Oxide, NTP TR 451 

TABLE A5 

Summary of the Incidence of Nonneoplastic Lesions in Male Rats in the 2-Year Inhalation Study of Nickel Oxide 

(continued) 

0 mg/m 3 0.62 mg/m ~ 1.25 mg/m ~ 2.5 mg/m ~ 

2-Year Study (continued) 

Urinary System 

Kidney (54) (53) (53) (52) 

Cyst 2 (4%) 1 (2%) 2 (4%) 1 (2%) 

Fibrosis 1 (2%) 

Infarct 1 (2%) 2 (4%) 

Necrosis 1 (2%) 

Nephropathy 47 (87%) 50 (94%) 48 (91%) 43 (83%) 

Pigmentation 1 (2%) 

Bilateral, nephropathy 1 (2%) 

Bilateral, cortex, cyst 1 (2%) 

Cortex, cyst 2 (4%) 1 (2%) 

Medulla, congestion 1 (2%) 

Medulla, cyst 1 (2%) 

Pelvis, degeneration 1 (2%) 

Pelvis, inflammation, suppurative 1 (2%) 

Urinary bladder (54) (53) (53) (52) 

Calculus, microscopic observation only 2 (4%) 1 (2%) 3 (6%) 

Inflammation, subacute 1 (2%) 

Metaplasia, squamous 1 (2%) 
171 

APPENDIX B 

SUMMARY OF LESIONS IN FEMALE RATS 

IN THE 2-YEAR INHALATION STUDY 

OF NICKEL OXIDE 

TABLE B1 

TABLE B2 

TABLE B3 

TABLE B4a 

TABLE B4b 

TABLE B5 

Summary of the Incidence of Neoplasms in Female Rats 

~n the 2-Year Inhalation Study of Nickel Oxide .......................... 173 

Individual Animal Tumor Pathology of Female Rats 

~n the 2-Year Inhalation Study of Nickel Oxide .......................... 178 

;tatistical Analysis of Primary Neoplasms in Female Rats 

in the 2-Year Inhalation Study of Nickel Oxide ........................... 200 

Historical Incidence of Lung Neoplasms 

in Untreated Female F344/N Rats ................................... 205 

Historical Incidence of Pheochromocytomas of the Adrenal Medulla 

~n Untreated Female F344/N Rats ................................... 206 

Summary of the Incidence of Nonneoplastic Lesions in Female Rats 

in the 2-Year Inhalation Study of Nickel Oxide .......................... 207 
172 Nickel Oxide, NTP TR 451 
Lesions in Female Rats 173 

TABLE B1 

Summary of the Incidence of Neoplasms in Female Rats in the 2-Year Inhalation Study of Nickel Oxide a 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 

Disposition Summary 

Animals initially in study 65 65 65 65 

7-Month interim evaluation 7 7 7 6 

15-Month interim evaluation 5 5 5 5 

Early deaths 

Moribund 27 24 27 25 

Natural deaths 5 3 6 3 

Survivors 

Terminal sacrifice 21 26 20 26 

Animals examined microscopically 65 65 65 65 

7-Month Interim Evaluation 

Alimentary System 

Mesentery (1) 

Lipoma 1 (100%) 

Systems Examined With No Neoplasms Observed 

Cardiovascular System 

Endocrine System 

General Bod~ System 

Genital System. 

Hematopoietic System 

Integumentary System 

Musculoskeletal System 

Nervous System 

Respiratory System 

Special Senses System 

Urinary System 

15-Month Interim Evaluation 

Endocrine System 

Pituitary gland (5) 

Pars distalis, adenoma 1 (20%) 

Pars intermedia, adenoma 

Thyroid gland (5) 

C-cell, adenoma I (20%) 

(5) 

3 (60%) 

(5) 

1 (20%) 

(5) 

(5) 

(5) 

1 (20%) 

1 (20%) 

(5) 

Genital System 

Uterus 

Polyp stromal 

(5) (5) (5) 

2 (40%) 

(5) 

1 (20%) 
174 Nickel Oxide, NTP TR 451 

TABLE B1 

Summary of the Incidence of Neoplasms in Female Rats in the 2-Year Inhalation Study of Nickel Oxide (continued) 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m ~ 

15-Month Interim Evaluation (continued) 

Systems Examined With No Neoplasms Observed 

Alimentary System 

Cardiovascular System 

General Body System 

Hematopoietic System 

Integumentary System 

Musculoskeletal System 

Nervous System 

Respiratory System 

Special Senses System 

Urinary System 

2-Year Study 

Alimentary System 

Esophagus (52) (53) (53) 

Lipoma 

Sarcoma, metastatic 1 (2%) 

Liver (53) (53) (53) 

Hepatocellular adenoma 1 (2 %) 

Sarcoma, metastatic 1 (2%) 

Mesentery 

Lipoma 

Pancreas (52) (53) (53) 

Salivary glands (52) (52) (51) 

Osteosarcoma, metastatic 1 (2%) 

Parotid gland, adenoma 

Stomach, forestomach (52) (53) (53) 

Tooth (I) 

Odontoma 1 (100%) 

(54) 

1 (2%) 

(54) 

1 (2%) 

(1) 

1 (100%) 

(54) 

(53) 

1. (2%) 

(54) 

(1) 

Cardiovascular System 

Blood vessel (3) (1) 

Heart (53) (53) 

Osteosarcon-ua, metastatic 1 (2%) 

(2) 

(53) (54) 

Endocrine System 

Adrenal cortex (53) (53) 

Carcinoma 1 (2%) 

Adrenal medulla (51) (52) 

Pheochromocytoma benign 3 (6%) 7 

Bilateral, pheochromocytoma benign 1 (2%) 

Islets, pancreatic (52) (53) 

Adenoma 1 (2%) 1 

Osteosarcoma, metastatic 1 

Pituitary gland (52) (52) 

Pars distalis, adenoma 20 (38%) 21 

Pars distalis, carcinoma 1 (2%) 3 

Thyroid gland (52) (52) 

C-cell, adenorna 1 (2%) 1 

(13%) 

(2%) 

(2%) 

(40%) 

(6 % ) 

(2%) 

(53) 

(53) 

5 (9%) 

1 (2%) 

(53) 

1 (2%) 

(52) 

19 (37%) 

1 (2%) 

(53) 

3 (6%) 

(54) 

(53) 

13 (25%) 

5 (9%) 

(54) 

(54) 

20 (37%) 

2 (4%) 

(53) : 

2 (4%) 
Lesions in Female Rats 175 

TABLE B1 

Summary of the Incidence of Neoplasms in Female Rats in the 2-Year Inhalation Study of Nickel Oxide (continued) 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m ~ 2.5 mg/m 3 

2-Year Study (continued) 

General Body System 

Tissue NOS (6) 

Fibroma 

Fibrosarcoma 1 (17%) 

Fibrous histiocytoma 

Lipoma 

Liposarcoma 

Osteosarcoma 1 (17%) 

Squamous cell carcinoma 2 (33 %) 

Oral, squamous cell carcinoma 1 (17%) 

(1) (3) (3) 

1 (33%) 

1 (lOO%) 

2 (67%) 

1 (33%) 

Genital System 

Clitoral gland (53) (53) (51) (50) 

Adenoma 1 (2%) 4 (8%) 1 (2%) 

Carcinoma 2 (4%) 1 (2%) 

Bilateral, adenoma 1 (2%) 1 (2%) 

Ovary (53) (53) (53) (54) 

Granulosa-theca tumor benign 1 (2 %) 

Uterus (53) (53) (52) (54) 

Polyp stromal 9 (17%) 2 (4%) 6 (12%) 5 (9%) 

Schwannoma malignant 1 (2 %) 

Vagina (2) (1) (1) 

Polyp 1 (50%) 

Hematopoietic System 

Bone marrow (52) (53) (53) (54) 

Lymph node (14) (6) (9) (3) 

Lymph node, bronchial (49) (50) (53) (52) 

Lymph node, mandibular (47) (45) (51) (49) 

Squamous cell carcinoma, metastatic 1 (2%) 

Lymph node, mesenteric (51) (53) (53) (54) 

Lymph node, mediastinal (48) (46) (48) (50) 

Spleen (53) (53) (53) (54) 

Hemangiosarcoma 1 (2%) 

Thymus (48) (49) (47) (47) 

Thymoma NOS 1 (2%) 

Integumentary System 

Mammary gland (53) 

Adenoma 1 (2%) 

Carcinoma 

Carcinoma, multiple 1 (2%) 

Fibroadenoma 11 (21%) 

Fibroadenoma, multiple 1 (2%) 

(53) (53) 

1 (2%) 1 (2%) 

2 (4%) 

1 (2%) 

11 (21%) 13 (25%) 

3 (6%) 2 (4%) 

(54) 

1 (2%) 

1 (2%) 

12 (22%) 
176 Nickel Oxide, NTP TR 451 

TABLE B1 

Summary of the Incidence of Neoplasms in Female Rats in the 2-Year Inhalation Study of Nickel Oxide (continued) 

0 mg/m 3 0.62 mg/m 3 1~25 mg/m 3 2.5 mg/m 3 

2-Year Study (continued) 

Integumentary System (continued) 

Skin 

Basal cell adenoma 

Fibroma 

Hemangioma 

Keratoacanthoma 

Papilloma 

Squamous cell carcinoma 

Squamous cell papilloma 

Subcutaneous tissue, fibroma 

Subcutaneous tissue, sarcoma 

(4) (3) (3) (5) 

1 (25%) 

1 (20%) 

1 (25%) 

2 (50%) 

1 (33%) 

1 (20%) 

1 (20%) 

1 (33%) 1 (20%) 

1 (33%) 

Musculoskeletal System 

Bone 

Rib, osteosarcoma 

Vertebra, schwannoma malignant, metastatic, 

peripheral nerve 

(53) (53) (53) (54) 

1 (2%) 

1 (2%) 

Nervous System 

Brain 

Carcinoma, metastatic 

Cerebellum, carcinoma, metastatic 

Cerebrum, carcinoma, metastatic 

Cerebrum, glioma NOS 

Cerebrum, osteosarcoma, metastatic 

Hypothalamus, carcinoma, metastatic 

Peripheral nerve 

Schwannoma malignant 

(53) (53) (53) (54) 

1 (2%) 1 (2%) 

2 (4%) 1 (2%) 

3 (6%) 1 (2%) 1 (2%) 

I (2%) 

1 (2%) 

1 (2%) 

(1) 

1 (100%) 

Respiratory System 

Lung 

Alveolar/bronchiolar adenoma 

Alveolar/bronchiolar adenoma, multiple 

Alveolar/bronchiolar carcinoma 

Alveolar/bronchiolar carcinoma, squamous 

differentiation 

Carcinoma, metastatic, adrenal cortex 

Osteosarcoma, metastatic 

(53) (53) (53) (54) 

1 (2%) 1 (2%) 3 (6%) 

1 (2%) 

3 (6%) 

2 (4%) 1 (2%) 

1 (2%) 

l (2%) 

Special Senses System 

Zymbal's gland 

Carcinoma 

(1) 

1 (100%) 
Lesions in Female Rats 177 

TABLE B1 

Summary of the Incidence of Neoplasms in Female Rats in the 2-Year Inhalation Study of Nickel Oxide (continued) 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m a 

2-Year Study (continued) 

Urinary System 

Kidney (53) (53) (53) 

Liposarcoma 1 (2%) 

Mesenchymal tumor 1 (2%) 

Mixed tumor malignant 

Nephroblastoma 1 (2%) 

Transitional epithelium, carcinoma 1 (2%) 

Urinary bladder (52) (53) (53) 

(54) 

1 (2%) 

(54) 

Systemic Lesions 

Multiple organs b (53) (53) (53) 

Leukemia mononuclear 22 (42%) 19 (36%) 21 (40%) 

(54) 

18 (33%) 

Neoplasm Summary 

Total animals with primary neoplasms c 

7-Month interim evaluation 1 

15-Month interim evaluation 1 4 2 

2-Year study 52 49 51 

Total primary neoplasms 

7-Month interim evaluation 1 

15-Month interim evaluation 2 4 2 

2-Year study 91 80 93 

Total animals with. benign neoplasms 

7-Month interim evaluation 1 

15-Month interim evaluation 1 4 2 

2-Year study 39 38 37 

Total benign neoplasms 

7-Month interim evaluation 1 

15-Month interim evaluation 2 4 2 

2-Year study 57 54 57 

Total animals with malignant neoplasms 

2-Year study 32 25 30 

Total malignant neoplasms 

2-Year study 33 25 35 

Total animals with metastatic neoplasms 

2-Year study 3 5 3 

Total metastatic neoplasms 

2-Year study 3 11 4 

Total animals with uncertain neoplasmsbenign or malignant 

2-Year study 1 1 1 

Total uncertain neoplasms 

2-Year study 1 1 1 

3 

50 

3 

97 

3 

41 

3 

70 

25 

27 

2 

3 

a Number of animals examined microscopically at the site and the number of animals with neoplasm 

b Number of animals with any tissue examined microscopically 

c Primary neoplasms: all neoplasms except metastatic neoplasms 
178 Nickel Oxide, NTP TR 451 

TABLE B2 

Individual Animal Tumor Pathology of Female Rats in the 2-Year Inhalation Study of Nickel Oxide: 0 mg/m 3 

Number of Days on Study 

3344455555566666666666666 

450665566890 1 223444567899 

843883 8346478246034548929 

Carcass ID Number 

0101 1 000000 1 0 1 1 0 1 1 0 1 00 1 1 1 

9081298 9797 1 72 1 8207 1 7 6 3 20 

68592 1 64580 1 344469709705 1 

Alimentary System 

Esophagus + + + + + + + + + + + + + + + + + + + M + + + + + 

Intestine large, colon A + + + + + + + + + + + + + + + + + + + + + + + + 

Intestine large, rectum A + + + + + + + + + + + + + + + + + + + + + + + + 

Intestine large, cecum' A + + + + + + + + + + + + + + + + + + + + + + + + 

Intestine small, duodenum A + + + + + + + + + + + + + + + + + + + + + + + + 

Intestine small, jejunum A + + + + + + + + + + + + + + + + + + + + + + + + 

Intestine small, ileum A + + + + + + + + + + + + + + + + + + + + + + + + 

Liver + + + + + + + + + + + + + + + + + + + + + + + + + 

Pancreas A + + + + + + + + + + + + + + + + + + + + + + + + 

Salivary glands + + + + + + + + + + + + + + + + + + + + + + + + + 

Stomach, forestomach A + + + + + + + + + + + + + + + + + + + + + + + + 

Stomach, glandular A + + + + + + + + + + + + + + + + + + + + + + + + 

Tooth 

Odontoma 

Cardiovascular System 

Blood vessel 

Heart 

+ + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

Endocrine System 

Adrenal cortex 

Carcinoma 

Adrenal medulla 

Pheochromocytoma benign 

Bilateral, pheochromocytoma benign 

Islets, pancreatic 

Adenoma 

Parathyroid gland 

Pituitary gland 

Pars distalis, adenoma 

Pars distalis, carcinoma 

Thyroid gland 

C-cell, adenoma 

++++++++++++++++++++++++'4- 

X 

+++++ + + + + + + + + + + + + + + + + + + + 

X 

A++++ + + + + + + + + + + + + + + + + + + + + 

M++++ + +M+'+ + + + + + + +M+ +M+ + + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

X X X X X X X 

X 

M++++ + +++++ + + + + + + + +++ ++ ++ 

General Body System 

Tissue NOS 

Fibrosarcoma 

Osteosarcoma 

Squamous cell carcinoma 

Oral, squamous cell carcinoma 

+ + + + 

X 

X 

X X 

Genital System 

Clitoral gland 

Adenoma 

Carcinoma 

+ + + + + + q-- + + + + + + + + + + + + + + + + + + 

X X 

+: Tissue examined microscopically M: Missing tissue X: Lesion present 

A: Autolysis precludes examination I: Insufficient tissue Blank: Not examined 
Lesions in Female Rats 179 

TABLE B2 

Individual Animal Tumor Pathology of Female Rats in the2-Year Inhalation Study of Nickel Oxide: 0 mg/m 3 

(continued) 

Number of Days on Study 

7777777777777777777777777777 

1111122222233333333333333333 

3344577999900111222222222222 

Carcass ID Number 

0 1 1 1 1 1 1 0 0 0 0 1 1 0 1 1 0 0 0 0 0 0 1 1 1 1 1 1 Total 

7 0 0 1 2 0 2 7 8 8 9 0 0 8 1 2 7 8 8 8 9 9 0 1 I 1 2 2 Tissues/ 

2 0 7 7 1 4 9 4 0 2 2 5 6 3 3 7 1 1 8 9 0 9 3 2 6 8 0 8 Tumors 

Alimentary System 

Esophagus 

Intestine large, colon 

Intestine large, rectum 

Intestine large, cecum 

Intestine small, duodenum 

Intestine small, jejunum 

Intestine small, ileum 

Liver 

Pancreas 

Salivary glands 

Stomach, forestomach 

Stomach, glandular 

Tooth 

Odontoma 

+ ++++ + + + + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

++ +++ + + + + + + + + + + + + + + + + + + + + + + + 

++ +++ + + + + + + + + + + + + + + + + + + + + + + + 

+ ++++ + + + + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

+ + +++ + + + + + + + + + + + + + + + + + + +I + + + 

+ ++++ + + + + + + + + + + -~ + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

+ 

X 

52 

52 

52 

52 

52 

52 

52 

52 

53 

52 

52 

52 

1 

1 

Cardiovascular System 

Blood vessel 

Heart +++++ + + + + + + + + + + + + + + + + + + + + + + + 

3 

53 

Endocrine System 

Adrenal cortex 

Carcinoma 

Adrenal medulla 

Pheochromocytoma benign 

Bilateral, pheochromocytoma benign 

Islets, pancreatic 

Adenoma 

Parathyroid gland 

Pituitary gland 

Pars distalis, adenoma 

Pars distalis, carcinoma 

Thyroid gland 

C-cell. adenoma 

+ ++++ + + + + + + + + + + + + + + + + + + + + + + + 

++M++ + + + + + + + + + + + + + + + + + + + + + + + 

X X 

X 

+ ++++ + + + + + + + + + + + + + + + + + + + + + + + 

X 

+M+++ +++ +++++M++++++++++ + ++ + 

+++++ + + + + + + + + + + + + + + + + + + + I + + + 

XXXX X X X X X X X X X 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

X 

53 

1 

51 

3 

1 

52 

1 

47 

52 

20 

1 

52 

1 

General Body System 

Tissue NOS 

Fibrosarcoma 

Osteosarcoma 

Squamous cell carcinoma 

Oral, squamous cell carcinoma 

+ 

X 

Genital System 

Clitoral gland 

Adenoma 

Carcinoma 

+ ++++ + + + + + + + + + + + + + + + + + + + + + + + 

X 

53 

t 

2 
180 Nickel Oxide, NTP TR 451 

TABLE B2 

Individual Animal Tumor Pathology of Female Rats in the 2-Year Inhalation Study of Nickel Oxide: 0 mg/m 3 

(continued) 

Number of Days on Study 

3344455555566666666666666 

4506655668901223444567899 

8438838346478246034548929 

Carcass ID Number 

0101100000010110110100111 

9081298979717218207176320 

6859216458013444697097051 

Genital System (continued) 

Ovary 

Granulosa-theca tumor benign 

Uterus 

Polyp stromal 

Vagina 

Polyp 

+++++ + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

X X X 

+ + 

X 

Hematopoietic System 

Bone marrow 

Lymph node 

Lymph node, bronchial 

Lyhaph node, mandibular 

Squamous cell carcinoma, metastatic 

Lymph node, mesenteric 

Lymph node, mediastinal 

Spleen 

Thymus 

Thymoma NOS 

A++++ + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + 

M++++ + +++I + +++++++ ++ + + + +M 

++++++ ++ +++++M+ +++ + + ++ + ++ 

X 

A ++++ + + + + + + + + + + + + + + + + + + + + 

+++++ + +M++I + +++++++ + + ++ +M 

+++++ + + + + + + + + + + + + + + + + + + + + 

+++++++++ +++++ + +M+I + +I ++ + 

Integumentary System 

Mammary gland 

Adenoma 

Carcinoma, multiple 

Fibroadenoma 

Fibroadenoma, multiple 

Skin 

Basal cell adenoma 

Keratoacanthoma 

Squamous cell papilloma 

+ + +++ + + + + + + + + + + + + + + + + + + + + 

XX X 

Musculoskeletal System 

Bone 

Skeletal muscle 

++ +++ + + + + + + + + + + + + + + + + + + + + 

Nervous System 

Brain 

Carcinoma, metastatic 

+ + +++ + + + + + + + + + + + + + + + + + + + + 

X 

Respiratory System 

Larynx 

Lung 

Alveolar/bronchiolar adenoma 

Carcinoma, metastatic, adrenal cortex 

Nose 

Trachea 

X 
Lesions in Female Rats 181 

TABLE B2 

Individual Animal Tumor Pathology of Female Rats in the 2-Year Inhalation Study of Nickel Oxide: 

(continued) 

0 mg/m ~ 

Number of Days on Study 

77 777 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 

1 1 1 I I 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 

3 3445 7 7 9 9 9 9 0 0 1 I 1 2 2 2 2 2 2 2 2 2 2 2 2 

Carcass ID Number 

0111111000011011000000111111 

7001202788900812788899011122 

2077149402256337118909326808 

Total 

Tissues/ 

Tumors 

Genital System (continued) 

Ovary 

Granulosa-theca tumor benign 

Uterus 

Polyp stromal 

Vagina 

Polyp 

+ ++++ + + + + + + + + + + + + + + + + + + ~ + + + + 

X 

+ + + ++ + + + + + + + + + + + + + + + + + + + + + + + 

X X X X X X 

53 

1 

53 

9 

2 

1 

Hematopoietic System 

Bone marrow 

Lymph node 

Lymph node, bronchial 

Lymph node, mandibular 

Squamous cell carcinoma, metastatic 

Lymph node, mesenteric 

Lymph node, mediastinal 

Spleen 

Thymus 

Thymoma NO.S 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + 

++++M++ + ++ + ++ + + ++ + + ++++ + + + + + 

++M+++ + +++ +++ ++ + +M+ +M+ + +I +M+ 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + 

++M++ + + + + + + + +M+ + + + + + + + + + + + + + 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + +M+ + + + + + +M+ + + + 

X 

52 

14 

49 

47 

1 

51 

48 

53 

48 

1 

Integumentary System 

Mammary gland 

Adenoma 

Carcinoma, multiple 

Fibroadenoma 

Fibroadenoma, multiple 

Skin 

Basal cell adenoma 

Keratoacanthoma 

Squamous cell papilloma 

+ + +++ + + + + + + + + + + + + + + ~ + + + + + + + + 

X 

X 

X X X X X X X X 

+ + + 

X 

X 

53 

1 

1 

i1 

1 

4 

1 

1 

2 

Musculoskeletal System 

Bone 

Skeletal muscle 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + 

+ 

53 

1 

Nervous System 

Brain 

Carcinoma, metastatic 

++ +++ + + + + + + + + + + + + + + + + + + + + + + + 53 

1 

Respiratory System 

Larynx 

Lung 

Alveolar/bronchiolar adenoma 

Carcinoma, metastatic, adrenal cortex 

Nose 

Trachea 

+ q-++ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + + + ÷ 

X 

+ ++++ + + + + + + + + + + + + + + + + + + + + + + + 

+ ++++ + + + + + + + + + + + + + + + + + + + + + + + 

53 

53 

1 

1 

53 

53 
182 Nickel Oxide, NTP TR 451 

TABLE B2 

Individual Animal Tumor Pathology of Female Rats in the 2-Year Inhalation Study of Nickel Oxide: 0 mg/m ~ 

(continued) 

Number of Days on Study 

3344455555566666666666666 

450665 566890 1 2234445 67 899 

8438838346478246034548929 

Carcass ID Number 

0101 1 000000 1 0 1 1 0 1 1 0 1 00 1 1 1 

90812989797 1 72 1 8207 1 76320 

6859216458013444697097051 

Special Senses System 

Eye + + + 

Urinary System 

Kidney 

Transitional epithelium, carcinoma 

Urinary bladder 

+ + +++ + + + + + + + + + + + + + + + + + + + + 

X 

A ++++ + + + + + + + + + + + + + + + + + + + + 

Systemic Lesions 

Multiple organs 

Leukemia mononuclear X X X X XX X X XX X 
Lesions in Female Rats 183 

TABLE B2 

Individual Animal Tumor Pathology of Female Rats in the 2-Year Inhalation Study of Nickel Oxide: 0 mg/m 3 

(continued) 

Number of Days on Study 

7777777777777777777777777777 

1111122222233333333333333333 

33445779999001 1 1222222222222 

Carcass ID Number 

0111111000011011000000111111 ~ml 

7001202788900812788899011122 Tissues/ 

2077149402256337118909326.808 Tumors 

Special Senses System 

Eye 

Urinary System 

Kidney 

Transitional epithelium, carcinoma 

Urinary bladder 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 53 

1 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 52 

Systemic Lesions 

Multiple organs 

Leukemia mononuclear 

+ + + + + + + -b + + + + + + + + + + + + + + + + + + + + 53 

XX X X X X X X X X X 22 
184 Nickel Oxide, NTP TR 451 

TABLE B2 

Individual Animal Tumor Pathology of Female Rats in the 2-Year Inhalation Study of Nickel Oxide: 0.62 mg/m 3 

Number of Days on Study 

4445555566666666666677777 

27702 3 3 30 1 22 3 45 6667 700 1 22 

32594667042940207848379 1 2 

Carcass ID Number 

22212 1 2 2 2 1 2 2 2 22 2 2 22 1 2 2 2 2 2 

33293 905 5 90 1 4 1 42 5 5 293 1 3 3 2 

13568879473005 8632390675 8 

Alimentary System 

Esophagus 

Intestine large, colon 

Intestine large, rectum 

Intestine large, cecum 

Intestine small, duodenum 

Intestine small, jejunum 

Intestine small, ileum 

Liver 

Hepatocellular adenoma 

Pancreas 

Salivary glands 

Osteosarcoma, metastatic 

Stomach, forestomach 

Stomach, glandular 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + ++ + + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

++ +++ + + + + + + + + + + + + + + + + + + + + 

+ + +++ + + + + + + + + + + + + + + + + + + + + 

+ ++++ + + + + + + + + + + + + + + + + + + + + 

+ + + ++ + + + + + + + + + + + + + + + + + + + + 

+ + +++ + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

+++++ ++M+++ ++++ + + +++ + + + + + 

X 

+++++ + + + + + + + + + + + + + + + + + + + + 

+ + + ++ + + + + + + + + + + + + + + + + + + + + 

Cardiovascular System 

Blood vessel 

Heart 

Osteosarcoma, metastatic 

+ 

+ + +++ + + + + + + + + + + + + + + + + + + + + 

X 

Endocrine System 

Adrenal cortex 

Adrenal medulla 

Pheochromocytoma benign 

Islets, pancreatic 

Adenoma 

Osteosarcoma, metastatic 

Parathyroid gland 

Pituitary gland 

Pars distalis, adenoma 

Pars distalis, carcinoma 

Thyroid gland 

C-cell, adenoma 

+ + +++ + + + + + + + + + + + + + + + + + + + + 

+ + +++ + + + + + + + + + + + + + + + + + + + + 

X X X X 

++ +++ + + + + + + + + + + + + + + + + + + + + 

X 

X 

+++++ + + + + + +M+ + + + + +MM+ + + + + 

+++++ + + + + + + + + + + + + + + + + + + + 

X X X X X X X X 

X X 

+ + +++ + + + + + + + + + A + + + + + + + + + + 

X 

General Body System 

Tissue NOS 

Fibrous histiocytoma 

Genital System 

Clitoral gland 

Adenoma 

Bilateral, adenoma 

Ovary 

Uterus 

Polyp stromal 

Vagina 

X X 

+ 
Lesions in Female Rats 185 

TABLE B2 

Individual Animal Tumor Pathology of Female Rats in the 2-Year Inhalation Study of Nickel Oxide: 0.62 mg/m 3 

(continued) 

Number of Days on Study 

7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 

2 2 2 22 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 

5 5 9 9 9 9 9 9 9 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 2 2 2 2 

Carcass ID Number 

2222222222222222222222222222 Total 

2200344450111223550014550111 Tissues/ 

2968917965278142780415019349 Tumors 

Alimentary System 

Esophagus 

Intestine large, colon 

Intestine large, rectum 

Intestine large, cecum 

Intestine small, duodenum 

Intestine small, jejunum 

Intestine small, ileum 

Liver 

Hepatocellular adenoma 

Pancreas 

Salivary glands 

Osteosarcoma, metastatic 

Stomach, forestomach 

Stomach, glandular 

+++++++++++++++++++++++-4-++++ 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + 

+ + q- + + + + + + + + + + + + + + + + ÷ + + + ÷ + + + + 

+ ++++ + + + + + + + + + + + + + + + + + + + + + + + 

+ + +++ + + + + + + + + + + + + + ÷ + + + + + + + + + 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + q- q- + + + q- + -I- + + h.- + 

X 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + 

++ +++ + + + + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + 

53 

53 

53 

53 

53 

53 

53 

53 

1 

53 

52 

1 

53 

53 

Cardiovascular System 

Blood vessel 

Heart 

Osteosarcoma, metastatic 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + 

1 

53 

1 

Endocrine System 

Adrenal cortex 

Adrenal medulla 

Pheochromocytoma benign 

Islets, pancreatic 

Adenoma 

Osteosarcoma, metastatic 

Parathyroid gland 

Pituitary gland 

Pars distalis, adenoma 

Pars distalis, carcinoma 

Thyroid gland 

C-cell, adenoma 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + 

++++M+ +++ ++ + + +++++ + + +++ + + + + + 

X X X 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + 

++++I +++++ + ++ +M+ + ++ ++ + +M+ + ++ 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

XXXXX X X XX XXXX 

X 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + 

53 

52 

7 

53 

1 

1 

47 

52 

21 

3 

52 

1 

General Body System 

Tissue NOS 

Fibrous histiocytoma 

Genital System 

Clitoral gland 

Adenoma 

Bilateral, adenoma 

Ovary 

Uterus 

Polyp stromal 

Vagina 

+ + + ++ + + + + + + + + + + + + + + + + + + + + + + + 

X X 

X 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + 

X X 

53 

4 

1 

53 

53 

2 

1 
186 Nickel Oxide, NTP TR 451 

TABLE B2 

Individual Animal Tumor Pathology of Female Rats in the 2-Year Inhalation Study of Nickel Oxide: 0.62 mg/m 3 

(continued) 

Number of Days on Study 

4445555566666666666677777 

277023 3 30 1 223456667700 1 22 

32594667042940207848379 1 2 

Carcass ID Number 

22212 1 222 1 222222222 1 22222 

33293 905 5 90 1 4 1 42 5 5 293 1 3 3 2 

13568 87947 3 005 8 6 3 2 3 9067 5 8 

Hematopoietic System 

Bone marrow 

Lymph node 

Lymph node, bronchial 

Lymph node, mandibular 

Lymph node, mesenteric 

Lymph node, mediastinal 

Spleen 

Hemangiosarcoma 

Thymus 

++ +++ + + + + + + + ÷ + + + + + + + + + + + + 

+ + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

+++++ + +M+ + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

+++++ + + +M+ +M+ + + + + + + + + + + + + 

+ + +++ + + + + + + + + + + + + + + + + + + + + 

X 

+++++ + + + + + + + +M+ + + + + + + + + + + 

Integumentary System 

Mammary gland 

Adenoma 

Fibroadenoma 

Fibroadenoma, multiple 

Skin 

Hemangioma 

+ ++++ + + + + + + + + + + + + + + + 

X X X 

X 

+++++ 

X X 

+++ 

X 

Musculoskeletal System 

Bone 

Rib, osteosarcoma 

+++++ + + + + + + + + + + + + + + + + + + ÷ + 

X 

Nervous System 

Brain 

Cerebellum, carcinoma, metastatic 

Cerebrum, carcinoma, metastatic 

Cerebrum, osteosarcoma, metastatic 

Hypothalamus, carcinoma, metastatic 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X X 

X X 

X 

Respiratory System 

Larynx 

Lung 

Osteosarcoma, metastatic 

Nose 

Trachea 

+ + +++ + + + + + + + + + + + + + + + + + + + + 

+ + +++ + + + + + + + + + + + + + + + + + + + + 

X 

+ + + + + + + + q- + + + + + + + + + + .+ ÷ + +. + + 

+ + + + + + .q- + + + + + + + + + + + + + + + + + • 

Special Senses System 

Eye + + 

Urinary System 

Kidney 

Mesenchymal tumor 

Urinary bladder 

+++++++++++++++++++++++.4-+ 

X 

+ + .+ + + + + + + + + -t- + ÷ + + + + + + + + + .q- + 

Systemic Lesions 

Multiple organs 

Leukemia mononuclear X X X X X X X X X X X 
Lesions in Female Rats 187 

TABLE B2 

Individual Animal Tumor Pathology of Female Rats in the 2-Year Inhalation Study of Nickel Oxide: 0.62 mg/m 3 

(continued) 

Number of Days on Study 

7777777777777777777777777777 

2222222223 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 

559999999000000000 1 1 1 1 1 1 2222 

Carcass ID Number 

2222222222222222222222222222 Total 

2 2 0 0 3 4 4 4 5 0 1 1 1 2 2 3 5 5 0 0 1 4 5 5 0 1 1 1 Tissues/ 

2 9 6 8 9 1 7 9 6 5 2 7 8 1 4 2 7 8 0 4 1 5 0 1 9 3 4 9 Tumors 

Hematopoietic System 

Bone marrow + + + + + + + + + q- + + + + + + + + + + + + + + + + + + 53 

Lymph node 6 

Lymph node, bronchial + + + + + + + + + + + M I + + + + + + + + + + + + M + + 50 

Lymph node, mandibular + + + + M + M + I + + + + + I + + + + + M M + + + + + M 45 

Lymph node, mesenteric + + + + + + + + + + + + + + + + + + + + + + + + + + + + 53 

Lymph node, mediastinal M + I + + + + + + + + + + + + + + + + + M + + + + M + M 46 

Spleen + + + + + + + + + + + + + + + + + + + + + + + + + + + + 53 

Hemangiosarcoma 1 

Thymus + + I MM + + + + + + + + + + + + + + + + + + + + + + + 49 

Integumentary System 

Mammary gland + + + + + + + + + + + + + + + + + + + + + + + + + + + + 53 

Adenoma X 1 

Fibroadenoma X X X X X X 11 

Fibroadenoma, multiple X X 3 

Skin 3 

Hemangioma l 

Musculoskeletal System 

Bone + + + + + + + + + + + + + + + + + + + + + + + + + + + + 53 

Rib, osteosarcoma 1 

Nervous System 

Brain 

Cerebellum, carcinoma, metastatic 

Cerebrum, carcinoma, metastatic 

Cerebrum, osteosarcoma, metastatic 

Hypothalamus, carcinoma, metastatic 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

X 

X 

53 

2 

3 

1 

1 

Respiratory System 

Larynx 

Lung 

Osteosarcoma, metastatic 

Nose 

Trachea 

4-4-4-4-4-4-4-+4-4-4-+++4-4-4-+4-4-4-4-4--I-4-++4- 

++++++++++++++++++4-+++++++++ 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + 

++++++++++++4-+++++++++++++++ 

53 

53 

1 

53 

53 

Special Senses System 

Eye 

Urinary System 

Kidney 

Mesenchymal tumor 

Urinary bladder 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + ÷ + + + + + + + + + + + + + + + 4- + 4- 4- 4- 

53 

1 

53 

Systemic Lesions 

Multiple organs 

Leukemia mononuclear 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 53 

X X X X X X X X 19 
188 Nickel Oxide, NTP TR 451 

TABLE B2 

Individual Animal Tumor Pathology of Female Rats in the 2-Year Inhalation Study of Nickel Oxide: 1.25 mg/m 3 

Number of Days on Study 

3444445 5555 66666666666666 

4367790 1 3 69 1 1 1 2 3 3 44445 8 8 9 

66616434654 1 4874803 375690 

Carcass ID Number 

33333 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 

68875478587865 86553.57685 3 

1924345 64 1 74527 8 1 5 66 870 8 5 

Alimentary System 

Esophagus + + + + + + + + + + + + + + + + + + + + + + + + + 

Sarcoma, metastatic X 

Intestine large, colon + + + + + + + + + + + + + + + + + + + + + + + + + 

Intestine large, rectum + + + + + + + + + + + + + + + + + I + + + + + + + 

Intestine large, cecum + + + + + + + + + + + + + + + + + + + + + + + + + 

Intestine small, duodenum + + + + + + + + + + + + + + + + + + + + + + + + + 

Intestine small, jejunum + + + + + + + + + + + + + + + + + + + + + + + + + 

Intestine small, ileum + + + + + + + + + + + + + + + + + + + + + + + + + 

Liver + + + + + + + + + + + + + + + + + + + + + + + + + 

Sarcoma, metastatic X 

Pancreas + + + + + + + + + + + + + + + + + + + + + + + + + 

Salivary glands + + + + + + M + + + + + + + + + + + + + + + + + + 

Stomach, forestomach + + + + + + + + + + + + + + + + + + + + + + + + + 

Stomach, glandular + + + + + + + + + + + + + + + + + + + + + + + + + 

Cardiovascular System 

Blood vessel 

Heart 

+ 

+++++ + + + + + + + + + + + + + + + + + + + + 

Endocrine System 

Adrenal cortex 

Adrenal medulla 

Pheochromocytoma benign 

Bilateral, pheochromocytoma benign 

Islets, pancreatic 

Adenoma 

Parathyroid gland 

Pituitary gland 

Pars distalis, adenoma 

Pars distalis, carcinoma 

Thyroid gland 

C-cell, adenoma 

+++++ + + + + + + + + + + + + + + + + + + + + 

+ + +++ + + + + + + + + + + + + + + + + + + + + 

X X 

+++++ + + + + + + + + + + + + + + + + + + + + 

+++++ + +MM+ + + + +M+ + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

X X X X X X X 

+ ++++ + + + + + + + + + + + + + + + + + + + + 

General Body System 

Tissue NOS 

Lipoma 

Liposarcoma 

+ + 

X 

X 

Genital System 

Clitoral gland 

Adenoma 

Bilateral, adenoma 

Ovary 

Uterus 

Polyp stromal 

Vagina 

+++++ + +M+ + + + + + + + + + + + + + + + + 

X 
Lesions in Female Rats 189 

TABLE B2 

Individual Animal Tumor Pathology of Female Rats in the 2-Year Inhalation Study of Nickel Oxide: 1.25 mg/m 3 

(continued) 

Number of Days on Study 

6 6 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 

9 9 1 1 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 

0 0 3 3 2 7 7 7 9 9 9 9 0 0 0 0 0 0 1 1 1 1 1 1 1 2 2 2 

Carcass ID Number 

3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 Total 

4 4 4 7 2 4 7 8 3 6 7 7 3 4 5 6 6 6 2 2 3 3 4 4 5 3 6 7 Tissues\ 

3 5 6 9 7 9 6 3 0 3 1 2 7 1 9 0 2 9 6 8 1 4 7 8 0 9 6 3 Tumors 

Alimentary System 

Esophagus 

Sarcoma, metastatic 

Intestine large, colon 

Intestine large, rectum 

Intestine large, cecum 

Intestine small, duodenum 

Intestine small, jejunum 

Intestine small, ileum 

Liver 

Sarcoma, metastatic 

Pancreas 

Salivary glands 

Stomach, forestomach 

Stomach, glandular 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + + + + 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + + + + 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + +I + + + + 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + 

53 

1 

53 

52 

53 

53 

53 

53 

53 

1 

53 

51 

53 

53 

Cardiovascular System 

Blood vessel 

Heart 

+ 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + 

2 

53 

Endocrine System 

Adrenal cortex 

Adrenal medulla 

Pheochromocytoma benign 

Bilateral, pheochromocytoma benign 

Islets, pancreatic 

Adenoma 

Parathyroid gland 

Pituitary gland 

Pars distalis, adenoma 

Pars distalis¢ carcinoma 

Thyroid gland 

C-cell, adenoma 

+ + + ++ + + + + + + + + + + + + + + ~ + + + + + + + + 

+ + ++ + + + + + + + + + + + + + + + + + + + + + + + + 

X X X 

X 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

X 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + +M+ + + + 

XX X X XX X X X X X X 

X 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + 

X X X 

53 

53 

5 

1 

53 

1 

50 

52 

19 

1 

53 

3 

General Body System 

Tissue NOS 

Lipoma 

Liposarcoma 

+ 

X 

Genital System 

Clitoral gland 

Adenoma 

Bilateral, adenoma 

Ovary 

Uterus 

Polyp stromal 

Vagina 

M++++ + + + + + + + + + + + + + + + + + + + + + + + 

X 

X 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + 

I ++++ + + + + + + + + + + + + + + + + + + + + + + + 

X X X X X 

+ 

51 

1 

1 

53 

52 

6 

1 
190 Nickel Oxide, NTP TR 451 

TABLE B2 

Individual Animal Tumor Pathology of 

(continued) 

Female Rats in the 2-Year Inhalation Study of Nickel Oxide: 1.25 mg/m 3 

Number of Days on Study 

344 

436 

666 

4445555566666666666666 

7790136911123344445889 

1643465414874803375690 

Carcass ID Number 

333 

688 

192 

3333333333333333333333 

7547858786586553576853 

4345641745278156687085 

Hematopoietic System 

Bone marrow + + + 

Lymph node 

Lymph node, bronchial + + + 

Lymph node, mandibular + + + 

Lymph node, mesenteric + + + 

Lymph node, mediastinal + + + 

Spleen + + + 

Thymus + + + 

+ + + + + + + + + + + + + + + + + + + + + + 

+ + + ++ 

++ + + + + + + + + + + + + + + + + + + + + 

++ +M+++ + + + + + + + + + + ++ + + + 

++ + + + + + + + + + + + + + + + + + + + + 

++ + +M+ + + + + + + +MM+ + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + 

++ + + + + + + + + + M + + + + + + + + + + 

Integumentary System 

Mammary gland 

Adenoma 

Carcinoma 

Carcinoma, multiple 

Fibroadenoma 

Fibroadenoma, multiple 

Skin 

Subcutaneous tissue, fibroma 

Subcutaneous tissue, sarcoma 

+ + +++ + + + + + + + + + + + + + + + + + + + + 

X 

X 

X X X X 

+ + + 

X 

X 

Musculoskeletal System 

Bone 

Vertebra, schwannoma malignant, 

metastatic, peripheral nerve 

+ + + + + + + + + + + + + + :~ + + + + + + + + + + 

X 

Nervous System 

Brain 

Cerebrum, carcinoma, metastatic 

Cerebrum, glioma NOS 

Peripheral nerve 

Schwannoma malignant 

+ ++++ + + + + + + + + + + + + + + + + + + + + 

X 

+ 

X 

Respiratory System 

Larynx 

Lung 

Alveolar/bronchiolar adenoma 

Alveolar/bronchiolar carcinoma 

Alveolar/bronchiolar carcinoma, 

squamous differentiation 

Nose 

Trachea 

+ ++++ + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

X 

X 

+ ++++ + + + + + + + + + + + + + + + + + + + + 

++ +++ + + + + + + + + + + + + + + + + + + + + 

Special Senses System 

Eye + + + + 
Lesions in Female Rats 191 

TABLE B2 

Individual Animal Tumor Pathology of Female Rats in the 2-Year Inhalation Study of Nickel Oxide: 1.25 mg/m 3 

(continued) 

Number of Days on Study 

6677777777777777777777777777 

9911222222223 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 

003327779999000000 1 1 1 1 1 1 1 222 

Carcass ID Number 

3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 Total 

4 4 4 7 2 4 7 8 3 6 7 7 3 4 5 6 6 6 2 2 3 3 4 4 5 3 6 7 Tissues/ 

3 5 6 9 7 9 6 3 0 3 1 2 7 1 9 0 2 9 6 8 l 4 7 8 0 9 6 3 Tumors 

Hematopoietic System 

Bone marrow 

Lymph node 

Lymph node, bronchial 

Lymph node, mandibular 

Lymph node, mesenteric 

Lymph node, mediastinal 

Spleen 

Thymus 

+++++ + + + + ~ + + + + + + + + + + + + + + + + + + 53 

+ + + + 9 

++ +++ + + + + + + + + + + + + + + + + + + + + + + + 53 

+ + + + + + + + + + + + + + + + + + + M -t- + + + + + + + 51 

++ +++ + + + + + + + + + + + + + + + + + + + + + + + 53 

+++++++ +++ +++ +M+++M++ +++ + + + + 48 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + 53 

+ + + + + + + + + + + + M + + M + + + + M + M + + + M + 47 

Integumentary System 

Mammary gland 

Adenoma 

Carcinoma 

Carcinoma, multiple 

Fibroadenoma 

Fibroadenoma, multiple 

Skin 

Subcutaneous tissue, fibroma 

Subcutaneous tissue, sarcoma 

+ + +++ + + + + + + + + + + q- + + + + + + + + + + + + 

X 

X 

X X X X XXX XX 

X X 

53 

1 

2 

1 

13 

2 

3 

1 

1 

Musculoskeletal System 

Bone 

Vertebra, schwannoma malignant, 

metastatic, peripheral nerve 

+ "-I- + + + + + + + + + + + + + + + + + + + + + + + + + + 53 

1 

Nervous System 

Brain 

Cerebrum, carcinoma, metastatic 

Cerebrum, glioma NOS 

Peripheral nerve 

Schwannoma malignant 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 

X 

53 

1 

1 

1 

1 

Respiratory System 

Larynx 

Lung 

AIveolar/bronchiolar adenoma 

AIveolar/bronchiolar carcinoma 

Alveolar/bronchiolar carcinoma, 

squamous differentiation 

Nose 

Trachea 

+ ++++ + + + + + + + + + + + + + + + + + + + + + + + 

+ q- -I- + + q- q- + + + + + + + + + + + + .4- + + + + + + + + 

X X 

53 

53 

1 

3 

X X 2 

++++++ + ++ + + + ++ + + + + ++ + + + + + + + 52 

+ + + + + + + + + + + + + + + + + + + + + -k- -I- + + + + + 53 

Special Senses System 

Eye + 5 
192 Nickel Oxide, NTP TR 451 

TABLE B2 

Individual Animal Tumor Pathology of Female Rats in the 2-Year Inhalation Study of Nickel Oxide: 1.25 mg/m 3 

(continued) 

Number of Days on Study 

344444555 5566666666666666 

43677 90 1 3 69 1 1 1 2 3 3 44445 8 8 9 

66616434654 1 487480337 5 690 

Carcass ID Number 

33333 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 

68875 47 8 5 87 8 65 8 65 5 3 5 7 6 8 5 3 

. 

1 9243 4 5 64 1 7 4 5 2 7 8 1 5 6 6 8 7 0 8 5 

Urinary System 

Kidney 

Liposarcoma 

Nephroblastoma 

Urinary bladder 

+ + +++ + + + + + + + + + + + + + + + + + + + + 

X 

X 

++ +++ + + + + + + + + + + + + + + + + + + + + 

Systemic Lesions 

Multiple organs 

Leukemia mononuclear XXX X XX XX XXXX 
Lesions in Female Rats 193 

TABLE B2 

Individual Animal Tumor Pathology of Female Rats in the 2-Year Inhalation Study of Nickel Oxide: 1.25 mg/m 3 

(continued) 

Number of Days on Study 

6 6 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 

9 9 1 1 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 

0 0 3 3 2 7 7 7 9 9 9 9 0 0 0 0 0 0 1 1 1 1 1 1 1 2 2 2 

Carcass ID Number 

3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 Total 

4 4 4 7 2 4 7 8 3 6 7 7 3 4 5 6 6 6 2 2 3 3 4 4 5 3 6 7 Tissues/ 

3 5 6 9 7 9 6 3 0 3 1 2 7 1 9 0 2 9 6 8 I 4 7 8 0 9 6 3 Tumors 

Urinary System 

Kidney 

Liposarcoma 

Nephroblastoma 

Urinary bladder 

+ + + + + + + + + + + + + + + + + + + + + + + "~- + + + + 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + 

53 

1 

1 

53 

Systemic Lesions 

Multiple organs 

Leukemia mononuclear 

+++++ + + + + + + + + + + + + + + + + + + + + + + + 53 

X X X X X X X X X 21 
194 Nickel Oxide, NTP TR 451 

TABLE B2 

Individual Animal Tumor Pathology of Female Rats in the 2-Year Inhalation Study of Nickel Oxide: 2.5 mg/m 3 

Number of Days on Study 

0444455555555666666666677 

96699 1 3 3 5 5777000 1 3 3 5 667 00 

067469890900707983 65 34 1 46 

Carcass ID Number 

4445455444444454454444454 

69618 1 09996899 1 78096975 1 8 

19673 I 5042725 1 82 1 97486896 

Alimentary System 

Esophagus 

Lipoma 

Intestine large, colon 

Intestine large, rectum 

Intestine large, cecum 

Intestine small, duodenum 

Intestine small, jejunum 

Intestine small, ileum 

Liver 

Hepatocellular adenoma 

Mesentery 

Lipoma 

Pancreas 

Salivary glands 

Parotid gland, adenoma 

Stomach, forestomach 

Stomach, glandular 

Tooth 

+ + +++ + + + + + + + + + + + + + + + + + + + + 

+ + +++ + + + + + + + + + + + + + + + + + + + + 

++ +++ + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

++ +++ + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

+ + +++ + + + + + + + + + + + + + + + + + + + + 

+ + +++ + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

++ +++ + + + + + + + + + + + + + + + + + + + + 

+ + +++ + + + + + + + + + + + + + + + + + + + + 

Cardiovascular System 

Heart + + + + + + + + + + + + + + + + + + + + + + + + + 

Endocrine System 

Adrenal cortex 

Adrenal medulla 

Pheochromocytoma benign 

Bilateral, pheochromocytoma benign 

Islets, pancreatic 

Parathyroid gland 

Pituitary gland 

Pars distalis, adenoma 

Pars distalis, carcinoma 

Thyroid gland 

C-cell, adenoma 

+ + +++ + + + + + + + + + + + + + + + + + + + + 

+++++ ++++++ +++++M++ + ++ + + + 

X X X X 

X 

+ + +++ + + + + q- + + + + + + + + + + + + + + + 

M+++M+M+ + ++++ + + + ++ +M++ ++ + 

+ + +++ + + + + + + + + + + + + + + + + + + + + 

X X X X X X X 

X X 

M + + + + + + ++ + + + + + + + + + + + + + + + + 

General Body System 

Tissue NOS 

Fibroma 

+ + 

X 

Genital System 

Clitoral gland 

Carcinoma 

Ovary 

Uterus 

Polyp stromal 

Schwannoma malignant 

+++++ + +M+ + + + + + + + + + + + + + +M+ 

X 

+ + +++ + + + + + + + + + + + + + + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

X 

X 
Lesions in Female Rats 195 

TABLE B2 

Individual Animal Tumor Pathology of Female Rats in the 2-Year Inhalation Study of Nickel Oxide: 2.5 mg/m 3 

(continued) 

Number of Days on Stud, y 

77777 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 

1 1222 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 

89599 9 9 9 9 9 9 0 0 0 0 0 0 1 1 I 1 1 1 1 2 2 2 2 2 

Carcass ID Number 

44544445555444455444455544444 Total 

67066790011778812678801156777 Tissues/ 

84725330245780860904932370159 Tumors 

Alimentary System 

Esophagus 

Lipoma 

Intestine large, colon 

Intestine large, rectum 

Intestine large, cecum 

Intestine small, duodenum 

Intestine small, jejunum 

Intestine small, ileum 

Liver 

Hepatocellula[ adenoma 

Mesentery 

Lipoma 

Pancreas 

Salivary glands 

Parotid gland, adenoma 

Stomach, forestomach 

Stomach, glandular 

Tooth 

++++++++++++ ++++ + + + + + + ++++ ++ + 54 

X 1 

+++++ + + + + + + + + + + + + + + + + + + + + + + + + 54 

++++++ + ++++++++ + + + + + + + + ++ + ++ + 54 

+++++ + + + + + + + + + + + + + + + + + + + + + + + + 54 

+++++ + + + + + + + + + + + + + + + + + + + + + + + + 54 

+++++ + + + + + + + + + + + + + + + + + + + + + + + + 54 

++++++ +++ ++ ++ + + + ++ +++ ++ + ++ + + + 54 

+++++ + + + + + + + + + + + + + + + + + + + + + + + + 54 

X 1 

+ 1 

X I 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + + 54 

+ + +++ + + + + + + + + + + + + + + + I + + + + + + + + 53 

X 1 

+ + +++ + + + + + + + + + + + + + + + + + + + + + + + + 54 

+++++ + + + + + + + + + + + + + + + + + + + + + + + + 54 

+ I 

Cardiovascular System 

Heart + + + + + + + + + + + + + + + + ÷ + + + + + + + + + + + + 54 

Endocrine System 

Adrenal cortex + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 54 

Adrenal medulla + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 53 

Pheochromocytoma benign X X X X X X X X X 13 

Bilateral, pheochromocytoma benign X X X X 5 

Islets, pancreatic + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 54 

Parathyroid gland + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Pituitary gland + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 54 

Pars distalis, adenoma X X X X X X X X X X X X X 20 

Pars distalis, carcinoma 2 

Thyroid gland + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 53 

C-cell, adenoma X X 2 

General Body System 

Tissue NOS + 3 

Fibroma 1 

Genital System 

Clitoral gland + + + + + + + + + + + M + + + + + + + M + + + + + + + + + 50 

Carcinoma 1 

Ovary + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 54 

Uterus + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 54 

Polyp stromal X X X X 5 

Schwannoma malignant 1 
196 Nickel Oxide, NTP TR 451 

TABLE B2 

Individual Animal Tumor Pathology 

(continued) 

of Female Rats in the 2-Year Inhalation Study of Nickel Oxide: 2.5 mg/m 3 

Number of Days on Study 

0444455555555666666666677 

96699 1 3 3 5 5 777000 1 3 3 5 66700 

06746989090070798 365 34 1 46 

Carcass ID Number 

4445455444444454454444454 

6961810999689917809697518 

1967315042725182197486896 

Hematopoietic System 

Bone marrow 

Lymph node 

Lymph node, bronchial 

Lymph node, mandibular 

Lymph node, mesenteric 

Lymph node, mediastinal 

Spleen 

Thymus 

+++++ + + + + + + + + + + + + + + + + + + + + 

+ + 

+ +M++ + + + + + + + + + + + + + + + + + + + + 

++ +++ + + + + + + + + + + + + + + + + + + + + 

+ + +++ + + + + + + + + + + + + + + + + + + + + 

M+++M+ + +I + + + + + + +M+ + + + + + + + 

+++++ + + + + + + + + + + + + + + + + + + + + 

+++++ + + + +M+M+ + + + +M+ + + + + + + 

Integumentary System 

.Mammary gland 

Adenoma 

Carcinoma 

Fibroadenoma 

Skin 

Fibroma 

Papilloma 

Squamous cell carcinoma 

Subcutaneous tissue, fibroma 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

X X X X 

+ 

X 

Musculoskeletal System 

Bone + + + + + + + + + + + + + + + + + + + + + + + + + 

Nervous System 

Brain 

Carcinoma, metastatic 

Cerebellum, carcinoma, metastatic 

Cerebrum, carcinoma, metastatic 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

X 

X 

Respiratory System 

Larynx 

Lung 

AIveolar/bronchiolar adenoma 

AIveolar/bronchiolar adenoma, 

multiple 

AIveolar/bronchiolar carcinoma, 

squamous differentiation 

Nose 

Trachea 

+ + + + + + + + + + + + + + ÷ + ÷ + + + + + + + • 

+ + +++ + + + + + + + + + + + + + + + + + + + + 

+ ++++ + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

Special Senses System 

Eye 

Zymbal's gland 

Carcinoma 

+ + 

+ 

X 
Lesions in Female Rats 197 

TABLE B2 

Individual Animal Tumor Pathology of Female 

(continued) 

Rats in the 2-Year Inhalation Study of Nickel Oxide: 2.5 mg/m 3 

Number of Days on Study 

77777777777777777777777777777 

I 1222 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 

89599 9 9 9 9 9 9 0 0 0 0 0 0 1 1 1 1 1 1 1 2 2 2 2 2 

Carcass ID Number 

445444455 5544445 5444455544444 Total 

67066 7 9 0 0 1 1 7 7 8 8 1 2 6 7 8 8 0 1 1 5 6 7 7 7 Tissues/ 

84725 3 3 0 2 4 5 7 8 0 8 6 0 9 0 4 9 3 2 3 7 0 I 5 9 Tumors 

Hematopoietic System 

Bone marrow + + + + + + + + + + + + + + + + + + + + + + + ,7. + + + + + 54 

Lymph node + 3 

Lymph node, bronchial + + M + + + + + + + + + + + + + + + + + + + + + + + + + + 52 

Lymph node, mandibular + + + + + + + + + M M M + M + + + + + M + + + + + + + + + 49 

Lymph node, mesenteric + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 54 

Lymph node, mediastinal + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Spleen + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 54 

Thymus + + + + + + + + M + M + + + + + + + + + + + + M + + + + M 47 

Integumentary System 

Mammary gland + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 54 

Adenoma X 1 

Carcinoma 1 

Fibroadenoma X X X X X X X X 12 

Skin + + + + 5 

Fibroma 1 

Papilloma 1 

Squamous cell carcinoma X 1 

Subcutaneou~ tissue, fibroma X 1 

Musculoskeletal System 

Bone + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 54 

Nervous System 

Brain + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 54 

Carcinoma, metastatic 1 

Cerebellum, carcinoma, metastatic 1 

Cerebrum, carcinoma, metastatic 1 

Respiratory System 

Larynx 

Lung 

Alveolar/bronchiolar adenoma 

Alveolar/bronchiolar adenoma, 

multiple 

Alveolar/bronchiolar carcinoma, 

squamous differentiation 

Nose 

Trachea 

+++++ + + + + + + + + + + + + + + + + + + + + + + + + 

+++++++.4-+++++++++++++++++++++ 

X X X 

54 

54 

3 

X 1 

X 

+++++++++++++++++++++++++.4-+++ 

+ + + + + + + + + + -I- + + + + + + + + + + + + + + + + + + 

1 

54 

54 

Special Senses System 

Eye 

Zymbal's gland 

Carcinoma 

÷ 
198 Nickel Oxide, NTP TR 451 

TABLE B2 

Individual Animal Tumor Pathology of Female Rats in the 2-Year Inhalation Study of Nickel Oxide: 2.5 mg/m 3 

(continued) 

Number of Days on Study 

0444455555555666666666677 

96699 1 3 3 5 5777000 1 3 3 5 66700 

06746989090070798 365 34 1 46 

Carcass ID Number 

4445455444444454454444454 

69618 1 09996899 1 78096975 1 8 

19673 1 5042725 1 82 1 97486896 

Urinary System 

Kidney 

Mixed tumor malignant 

Urinary bladder 

+++++ + + + + + + + + + + + + + + + + + + + + 

X 

+ ++++ + + + + + + + + + + + + + + + + + + + + 

Systemic Lesions 

Multiple organs 

Leukemia mononuclear X X X XX XXX X X 
Lesions in Female Rats 199 

TABLE B2 

Individual Animal Tumor Pathology of Female Rats in the 2-Year Inhalation Study of Nickel Oxide: 2.5 mg/m ~ 

(continued) 

Number of Days on Study 

77777777777777777777777777777 

1 12222222223 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 

89599999999000000 1 1 1 1 1 1 1 22222 

Carcass ID Number 

44544 4 4 5 5 5 5 4 4 4 4 5 5 4 4 4 4 5 5 5 4 4 4 4 4 Toml 

67066790011778812678801156777 Tissues/ 

84725 3 3 0 2 4 5 7 8 0 8 6 0 9 0 4 9 3 2 3 7 0 1 5 9 Tumor 

Urinary System 

Kidney 

Mixed tumor malignant 

Urinary bladder 

++++++++++++++ +++++ + + ++++ ++ + + 54 

1 

+++++ + + + + + + + + + + + + + + + + + + + + + + + + 54 

Systemic Lesions 

Multiple organs 

Leukemia mononuclear 

+++++ + + + + + + + + + + + + + + + + + + + + + + + + 54 

XX XX XX X X 18 
200 Nickel Oxide, NTP TR 451 

TABLE B3 

Statistical Analysis of Primary Neoplasms in Female Rats in the 2-Year Inhalation Study of Nickel Oxide 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m ~ 2.5 mg/m ~ 

Adrenal Medulla: Benign Pheochromocytoma 

Overall rate a 4/51 (8%) 7/52 (13%) 6/53 (11%) 18/53 (34%) 

Adjusted rate b 15.1% 21.1% 22.0% 56.5 % 

Terminal rate c 2/21 (10%) 3/25 (12%) 2/20 (10%) 13/26 (50%) 

First incidence (days) 558 524 611 519 

Life table test d P<0.001 P=0.350 P=0.353 P=0.003 

Logistic regression test d P < 0.001 P=0.288 P-~0.385 P =0.001 

Cochran-Armita~e test d P < 0.001 

Fisher exact test u P = 0.274 P = 0.395 P < 0.001 

Clitoral Gland: Adenoma 

Overall rate 1/53 (2%) 

Adjusted rote 4.8 % 

Terminal rate 1/21 (5%) 

First incidence (days) 729 (T) 

Life table test P=0.151N 

Logistic regression test P=0.183N 

Cochran-Armitage test P=0.176N 

Fisher exact test 

Clitoral Gland: Adenoma or Carcinoma 

Overall rate 3/53 (6%) 

Adjusted rate 9.8 % 

Terminal rate 1/21 (5%) 

First incidence (days) 594 

Life table test P=0.136N 

Logistic regression test P=0.158N 

Cochran-Armitage test P=0.154N 

Fisher exact test 

Lung: Alveolar/bronchiolar Adenoma 

Overall rate 1/53 (2%) 

Adjusted rate 4.8% 

Terminal rate 1/21 (5%) 

First incidence (days) 729 (T) 

Life table test P=0.044 

Logistic regression test P=0.032 

Cochran-Armitage test P=0.035 

Fisher exact test 

Lung: Alveolar/bronchiolar Carcinoma 

Overall rate 0/53 (0%) 

Adjusted rate 0.0% 

Terminal rate 0/21 (0%) 

First incidence (days) -- 

Life table test P=0.302 

Logistic regression test P=0.262 

Cochran-Armitage test P=0.272 

Fisher exact test 

5/53 (9%) 2/51 (4%) 0/50 (0%) 

16.2% 10.0% 0.0% 

3/26 (12%) 2/20 (10%) 0/24 (0%) 

e 537 729 (T) -- 

P=0.145 P=0.483 P=0.473N 

P=0.114 P=0.483 P=0.473N 

P=0.103 P=0.485 P=0.515N 

5/53 (9%) 2/51 (4%) 1/50 (2%) 

16.2% 10.0% 2.5% 

3/26 (12%) 2/20 (10%) 0/24 (0%) 

537 729 (T) 607 

P=0.436 P=0.519N P=0.305N 

P=0.367 P=0.521N P=0.324N 

P=0.358 P=0.518N P=0.331N 

0/53 (0%) 1/53 (2%) 4/54 (7%) 

0.0% 3.1% 15.4% 

0/26 (0%) 0/20 (0%) 4/26 (15%) 

-- 655 729 (T) 

P =0.457N P = 0.748 P=0.245 

P=0.457N P =0.759 P= 0.245 

P=0.500N P=0.752N P=0.187 

0/53 (0%) 5/53 (9%) 1/54 (2%) 

0.0% 22.3% 3.8% 

0/26 (0%) 4/20 (20%) 1/26 (4%) 

-- 643 729 (T) 

-- P = 0..029 P = 0.543 

-- P=0.029 P=0.543 

P=0.028 P=0.505 
Lesions in Female Rats 201 

TABLE B3 

Statistical Analysis of Primary Neoplasms in Female Rats in the 2-Year Inhalation Study of Nickel Oxide (continued) 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 

Lung: Alveolar/bronchiolar Adenoma or Carcinoma 

Overall rate 1/53 (2%) 0/53 (0%) 6/53 (I 1%) 5/54 (9%) 

Adjusted rate 4.8% 0.0% 24.7% 19.2% 

Terminal rate 1/21 (5 %) 0/26 (0%) 4/20 (20%) 5/26 (19%) 

First incidence (days) 729 (T) -- 643 729 (T) 

Life table test P=0.035 P=0.457N P=0.051 P=0.152 

Logistic regression test P=0.022 P=0.457N P=0.053 P=0.152 

Cochran-Armitage test P=0.026 

Fisher exact test P =0.500N P = 0.056 P = 0.107 

Mammary Gland: Fibroadenoma 

Overall rate 12/53 (23%) 

Adjusted rate 40.9% 

Terminal rate 6/21 (29 %) 

First incidence (days) 468 

Life table test • P=0.414N 

Logistic regression test P=0.510N 

Cochran-Armitage test P=0.481N 

Fisher exact test 

Mammary Gland: Fibroadenoma or Adenoma 

Overall rate 13/53 (25%) 

Adjusted rate 44.8% 

Terminal rate 7/21 (33%) 

First incidence (days) 468 

Life table test. P=0.409N 

Logistic regression'test P=0.511N 

Cochran-Armitage test P=0.480N 

Fisher exact test 

Mammary Gland: Carcinoma 

Overall rate 1/53 (2%) 

Adjusted rate 4.8% 

Terminal rate 1/21 (5%) 

First incidence (days) 729 (T) 

Life table test P=0.511 

Logistic regression test P=0.488 

Cochran-Armitage test P=0.492 

Fisher exact test 

Mammary Gland: Adenoma or Carcinoma 

Overall rate 2/53 (4%) 

Adjusted rate 9.5 % 

Terminal rate 2/21 (10%) 

First incidence (days) 729 (T) 

Life table test P=0.525 

Logistic regression test P=0.488 

Cochran-Armitage test P=0.498 

Fisher exact test 

14/53 (26%) 15/53 (28%) 12/54 (22%) 

40.1% 52.5 % 37.4 % 

7/26 (27%) 8/20 (40%) 8/26 (31%) 

475 614 467 

P=0.574N P=0.297 P=0.439N 

P=0.445 P=0.305 P=0.578N 

P=0.411 P=0.328 P=0.571N 

15/53 (28%) 16/53 (30%) 13/54 (24%) 

43.3% 53.6% 40.9% 

8/26 (31%) 8/20 (40%) 9/26 (35%) 

475 611 467 

P=0.555N P=0.301 P=0.422N 

P=0.455 " P=0.309 P=0.575N 

P=0.413 P=0.332 P=0.567N 

0/53 (0%) 3/53 (6%) 1/54 (2%) 

0.0% 12.6% 2.1% 

0/26 (0%) 2/20 (10%) 0/26 (0%) 

-- 643 538 

P=0.457N P=0.290 P=0.737N 

P=0.457N P=0.294 P=0.756N 

P=0.500N P=0.309 P=0.748N 

1/53 (2%) 4/53 (8%) 2/54 (4%) 

3.8% 14.7% 5.8% 

1/26 (4%) 2/20 (10%) 1/26 (4%) 

729 (T) 611 538 

P=0.425N P=0.323 P=0.636N 

P=0.425N P=0.327 P=0.690N 

P=0.500N P=0.339 P=0.684N 
202 Nickel Oxide, NTP TR 451 

TABLE B3 

Statistical Analysis of Primary Neoplasms in Female Rats in the 2-Year Inhalation Study of Nickel Oxide (continued) 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 

Mammary Gland: Fibroadenoma, Adenoma, or Carcinoma 

Overall rate 13/53 (25%) 15/53 (28%) 17/53 (32%) 14/54 (26%) 

Adjusted rate 44.8% 43.3% 54.9% 42.1% 

Terminal rate 7/21 (33 % ) 8/26 (31%) 8/20 (40 %) 9/26 (35 %) 

First incidence (days) 468 475 611 467 

Life table test P=0.506N P=0.555N P=0.237 P=0.509N 

Logistic regression test P=0.476 P=0.455 P=0.238 P=0.516 

Cochran-Armitage test P=0.505 

Fisher exact test P=0.413 P=0.259 P=0.522 

Pituitary Gland (Pars Distalis): Adenoma 

Overall rate 20/52 (38%) 

Adjusted rate 57.4% 

Terminal rate 7/20 (35 %) 

First incidence (days) 403 

Life table test P=0.378N 

Logistic regression test P=0,479N 

Cochran-Arrnitage test P=0,437N 

Fisher exact test 

21/52 (40%) 19/52 (37%) 20/54 (37%) 

60.1% 60.3% 55.7% 

13/26 (50%) 8/19 (42%) 11/26 (42%) 

614 536 539 

P=0,375N P=0.548N P=0.381N 

P=0.575N P=0.519N P=0.524N 

P=0.500 P=0.500N P=0.519N 

Pituitary Gland (Pars Distalis): Carcinoma 

Overall rate 1/52 (2%) 

Adjusted rate 2.2% 

Terminal rote 0/20 (0%) 

First incidence (days) 563 

Life table test P=0.527 

Logistic regression test P=0.579 

Cochran-Arrnitage test P=0.544 

Fisher exact test 

3/52 (6%) 1/52 (2%) 2/54 (4%) 

7.5% 3.8% 5.1% 

0/26 (0%) 0/19 (0%) 0/26 (0%) 

509 713 550 

P=0.326 P=0.747 P=0.490 

P=0.221 P=0.762N P=0.531 

P=0.309 P=0.752N P=0.514 

Pituitary Gland (Pars Distalis): Adenoma or Carcinoma 

Overall rate 21/52 (40%) 24/52 (46%) 20/52 (38%) 22/54 (41%) 

Adjusted rate 58.3 % 63.1% 61.8 % 58.0% 

Terminal rate 7/20 (35%) 13/26 (50%) 8/19 (42%) 11/26 (42%) 

First incidence (days) 403 509 536 539 

Life table test P=0.408N P=0.506N P=0.550N P=0.454N 

Logistic regression test P=0.497N P=0.397 P=0.518N P=0.560 

Cochran-Armitage test P=0.461N 

Fisher exact test P=0.346 P=0.500N P=0,564 

Skin: Papilloma, Squamous Cell Papilloma, Keratoacanthoma, Basal Cell Adenoma, or Squamous Cell Carcinoma 

Overall rate 4/53 (8%) 0/53 (0%) 0/53 (0%) 2/54 (4%) 

Adjusted rate 16.2% 0.0% 0.0% 7.2% 

Terminal rate 3/21 (14%) 0/26 (0%) 0/20 (0%) 1/26 (4%) 

First incidence (days) 564 -- -- 718 

Life table test P=0.324N P=0.045N P=0.069N P=0.261N 

Logistic regression test P=0.363N P=0.058N P=0.065N P=0.329N 

Cochran-Armitage test P=0.354N 

Fisher exact test P=0.059N P=0.059N P=0.330N 
Lesions in Female Rats 203 

TABLE B3 

Statistical Analysis of Primary Neoplasms in Female Rats in the 2-Year Inhalation Study of Nickel Oxide (continued) 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 

Thyroid Gland (C-cell): Adenoma 

Overall rate 1/52 (2%) 

Adjusted rate 4.8% 

Terminal rate 1/21 (5%) 

First incidence (days) 729 (T) 

Life table test P=0.378 

Logistic regression test P=0.333 

Cochran-Armitage test P=0.343 

Fisher exact test 

Tissue NOS: Squamous Cell Carcinoma 

Overall rate 3/53 (6%) 

Adjusted rate 9.6% 

Terminal rate 0/21 (0%) 

First incidence (days) 586 

Life table test P=0.055N 

Logistic regression test P=0.052N 

Coehran-Armitage test P=0.052N 

Fisher exact test 

Uterus: Stromal Polyp 

Overall rate 9/53 (17%) 

Adjusted rate 34.3 % 

Terminal rate 6/21 (29%) 

First incidence (days) 618 

Life table test P=0.259N 

Logistic regression test P=0.309N 

Cochran-Armitage test P=0.293N 

Fisher exact test 

All Organs: Mononuclear Cell Leukemia 

Overall rate: 22/53 (42%) 

Adjusted rate: 57.2% 

Terminal rate: 7/21 (33%) 

First incidence (days) 348 

Life table test P=0.269N 

Logistic regression test P=0.254N 

Cochran-Armitage test P=0.257N 

Fisher exact test 

All Organs: Benign Neoplasms 

Overall rate 40/53 (75%) 

Adjusted rate 90.6% 

Terminal rate 17/21 (81%) 

First incidence (days) 403 

Life table test P=0.433N 

Logistic regression test P=0.444 

Cochran-Armitage test P=0.512 

Fisher exact test 

1/52 (2%) 3/53 (6%) 2/53 (4%) 

2.4% 15.0% 7.7% 

0/26 (0%) 3/20 (15%) 2/26 (8%) 

634 729 (T) 729 (T) 

P=0.728N P=0.284 P=0.575 

P=0.759N P=0.284 P=0.575 

P=0.752N P=0.316 P=0.507 

0/53 (0%) 0/53 (0%) 0/54 (0%) 

0.0% 0.0% 0.0% 

0/26 (0%) 0/20 (0%) 0/26 (0%) 

-- -- -- 

P=0. 110N P=0.134N P=0.119N 

P=0.119N P=0.122N P=0.118N 

P=0.121N P=0.121N P=0. 118N 

2/53 (4%) 6/53 (11%) 5/54 (9%) 

7.3% 21.6% 17.0% 

1/26 (4%) 1/20 (5%) 4/26 (15%) 

725 594 466 

P=0.014N P=0.321N P=0.122N 

P=0.019N P=0.303N P=0.186N 

P=0.026N P=0.289N P=0.185N 

19/53 (36%) 21/53 (40%) 18/54 (33%) 

47.7% 55.6% 44.7% 

8/26 (31%) 6/20 (30%) 6/26 (23%) 

423 494 466 

P=0.222N P=0.545N P=0.221N 

P=0.359N P=0.502N P=0.250N 

P=0.345N P=0.500N P=0.250N 

39/53 (74%) 37/53 (70%) 41/54 (76%) 

86.3% 92.2% 95.2% 

20/26 (77%) 17/20 (85%) 24/26 (92%) 

475 466 466 

P = 0.194N P = 0.469N P = 0.340N 

P=0.411N P=0.349N P=0.553 

P=0.500N P=0.332N P=0.567 
204 Nickel Oxide, NTP TR 451 

TABLE B3 

Statistical Analysis of Primary Neoplasms in Female Rats in the 2-Year Inhalation Study of Nickel Oxide (continued) 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 

All Organs: Malignant Neoplasms 

Overall rate 32/53 (60%) 

Adjusted rate 69.3 % 

Terminal rate 8/21 (38%) 

First incidence (days) 348 

Life table test P=0.193N 

Logistic regression test P=0.110N 

Cochran-Armitage test P=0.134N 

Fisher exact test 

All Organs: Benign or Malignant Neoplasms 

Overall rate 52/53 (98%) 

Adjusted rate 98.1% 

Terminal rate 20/21 (95%) 

First incidence (days) 348 

Life table test P=0.318N 

Logistic regression test P=0.277N 

Cochran-Armitage test P=0.226N 

Fisher exact test 

26/53 (49%) 30/53 (57%) 25/54 (46%) 

57.9% 72.2% 55.0% 

9/26 (35%) 10/20 (50%) 7/26 (27%) 

423 436 466 

P =0.121N P=0.502N P =0.136N 

P=0.177N P=0.416N P=0.091N 

P=0.165N P = 0.422N P=0.103N 

49/53 (92%) 51/53 (96%) 50/54 (93%) 

94.2% 100.0% 96.2% 

23/26 (88%) 20/20 (100%) 24/26 (92%) 

423 436 466 

P=0.123N P=0.512 P=0.217N 

P=0.185N P=0.497N P=0.207N 

P=0.181N P=0.500N P=0.187N 

(T)Terminal sacrifice 

a Number of neoplasm-bearing animals/number of animals examined. Denominator is number of animals examined microscopically for adrenal gland, 

clitoral gland, lung, pituitary gland, and thyroid gland; for other tissues, denominator is number of animals necropsied. 

b Kaplan-Meier estimated neoplasm incidence at the end of the study after adjustment for intercurrent mortality 

c Observed incidence at terminal kill 

d Beneath the control incidence are the P values associated with the trend test. Beneath the exposed group incidence are the P values corresponding to 

pairwise comparisons between the controls and that exposed group. The life table test regards neoplasms in animals dying prior to terminal kill as being 

(directly or indirectly) the cause of death. The logistic regression test regards these lesions as nonfatal. The Cochran-Armitage and Fisher exact tests 

compare directly the overall incidence rates. For all tests, a negative trend or a lower incidence in an exposure group is indicated by N. 

e Not applicable; no neoplasms in animal group 
Lesions in Female Rats 205 

TABLE B4a 

Historical Incidence of Lung Neoplasms ill Untreated Female F344/N Rats a 

Incidence in Controls 

Study Alveolar/bronchiolar Alveolar/bronchiolar 

Adenoma Carcinoma 

Squamous Cell 

Carcinoma 

Alveolar/bronchiolar 

Adenoma or Carcinoma 

or Squamous Cell 

Carcinoma 

Historical Incidence at Lovelace Inhalation Toxicology Research Institute 

Nickel Oxide 1/53 0/53 0/53 1/53 

Nickel Subsulfide 2/53 0/53 0/53 2/53 

Nickel Sulfate Hexahydrate 0/52 0/52 0/52 0/52 

Talc b I/50 0/50 0/50 1/50 

Overall Historical Incidence in Inhalation Studies 

Total 7/700 (1.1%) 

Standard deviation 1.5 % 

Range 0 % -4 % 

0/700 (0%) 0/700 (0 %) 8/700 (1.1%) 

1.5% 

0%-4% 

Overall Historical Incidence in Feed Studies 

Total 20/1,201 (1.7%) 

Standard deviati6n 2.2 % 

Range 0%-10% 

5/1,201 (0.4%) 

0.8% 

0%-2% 

0/1,201 (0%) 25/1,201 (2.1%) 

2.2% 

0%-10% 

a Data as of 17 June 1994 

b Results of lifetime study; others are 2-year studies 
206 Nickel Oxide, NTP TR 451 

TABLE B4b 

Historical Incidence of Pheochromocytomas of the Adrenal Medulla in Untreated Female F344/N Rats a 

Incidence in Controls 

Study Benign Complex Malignant NOS Benign, Complex, 

Malignant, or NOS 

Historical Incidence at Lovelace Inhalation Toxicology Research Institute b 

Nickel Oxide 4/51 0/51 0/51 0/51 4/51 

Nickel Subsulfide 2/53 0/53 1/53 0/53 3/53 

Nickel Sulfate Hexahydrate 2/51 0/51 0/51 0/51 2/51 

Overall Historical Incidence in Inhalation Studies 

Total 35/608 (5.8%) 2/608 (0.3%) 1/608 (0.2%) 1/608 (0.2%) 39/608 (6.4%) 

Standard deviation 4.9 % 1.1% 0.6 % 0.6 % 4.4 % 

Range 0%-14% 0%-4% 0%-2% 0%-2% 2%-14% 

Overall Historical Incidence in Feed Studies 

Total . 49/1,175 (4.2%) 2/1,175 (0.2%) 6/1,175 (0.5%) 6/1,175 (0.5%) 62/1,175 (5.3%) 

Standard deviation 2.5 % 0.6 % 0.9 % 2.5 % 2.8 % 

Range 0%-8% 0%-2% 0%-2% 0%-12% 2%-12% 

a Data as of 17 June 1994 

b Talc excluded because it was not a 2-year study. 
Lesions in Female Rats 207 

TABLE B5 

Summary of the Incidence of Nonneoplastic Lesions in Female Rats in the 2-Year Inhalation Study of Nickel Oxide a 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 

Disposition Summary 

. 

Animals initially in study 65 65 65 65 

7-Month interim evaluation 7 7 7 6 

15-Month interim evaluation 5 5 5 5 

Early deaths 

Moribund 27 24 27 25 

Natural deaths 5 3 6 3 

Survivors 

Terminal sacrifice 21 26 20 26 

Animals examined microscopically 65 65 65 65 

7-Month Interim Evaluation 

Alimentary System 

Liver (1) 

Hepatodiaphragmatic nodule 1 (100%) 

Endocrine System 

Pituitary gland 

Pars distalis, hyperplasia, diffuse 

(2) 

2 (100%) 

(3) 

3 (100%) 

(1) 

1 (100%) 

Genital System 

Ovary 

Cyst 

(2) 

2 (100%) 

Hematopoietic System 

Lymph node, bronchial (6) (7) (7) (6) 

Hyperplasia, lymphoid 4 (57%) 3 (50%) 

Pigmentation 7 (100%) 6 (100%) 

Lymph node, mediastinal (6) (7) (6) (5) 

Pigmentation 2 (33%) 3 (60%) 

Respiratory System 

Lung (7) (7) (7) (6) 

Inflammation, chronic 1 (14%) 7 (100%) 6 (100%) 

Alveolar epithelium, pigmentation 1 (14%) 

Alveolus, pigmentation 5 (71%) 7 (100%) 6 (100%) 

Special Senses System 

Eye 

Cornea, degeneration 

(1) 

1 (100%) 

a Number of animals examined microscopically at the site and the number of animals with lesion 
208 Nickel Oxide, NTP TR 451 

TABLE B5 

Summary of the Incidence of Nonneoplastic Lesions in Female Rats in the 2-Year Inhalation Study of Nickel Oxide 

(continued) 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m a 

7-Month Interim Evaluation (continued) 

Urinary System 

Kidney (7) (7) (7) (6) 

Cortex, infiltration cellular, lymphocyte 1 (14%) 1 (17%) 

Urinary bladder (1) 

Edema, focal 1 (100%) 

Systems Examined With No Lesions Observed 

Cardiovascular System 

General Body System 

Integumentary System 

Musculoskeletal System 

Nervous System 

15-Month Interim Evaluation 

Endocrine System 

Adrenal medulla 

Hyperplasia 

Pituitary gland 

Pars distalis, hyperplasia 

Pars distalis, hyperplasia, cystic 

(5) 

1 (20%) 

(5) 

1 (20%) 

(5) 

(5) 

(4) 

1 (25%) 

(5) 

1 (20%) 

(5) 

(5) 

Genital System 

Ovary 

Cyst 

(5) 

1 (20%) 

(5) 

2 (40%) 

(5) 

1 (20%) 

(5) 

Hematopoietic System 

Lymph node 

Hyperplasia, lymphoid 

Lymph node, bronchial 

Hyperplasia, lymphoid 

Pigmentation 

Lymph node, mediastinal 

Hyperplasia, lymphoid 

Pigmentation 

(5) 

(5) 

(5) 

4 (80%) 

(5) 

3 (60%) 

(5) 

3 (60%) 

5 (100%) 

(4) 

4 (100%) 

(1) 

I (100%) 

(5) 

3 (60%) 

5 (100%) 

(4) 

3 (75%) 

3 (75%) 

Nervous System 

Brain 

Ventricle, ectasia 

(5) 

1 (20%) 

(5) (5) (5) 

Respiratory System 

Lung 

Inflammation, chronic 

Alveolus, pigmentation 

(5) 

3 (60%) 

(5) 

4 (80%) 

5 (100%) 

(5) 

5 (100%) 

5 (100%) 

(5) 

5 (100%) 

5 (100%) 
Lesions in Female Rats 209 

TABLE B5 

Summary of the Incidence of Nonneoplastic Lesions in Female Rats in the 2-Year Inhalation Study of Nickel Oxide 

(continued) 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 

15-Month Interim Evaluation (continued) 

Urinary System 

Kidney (5) 

Nepbropathy 4 (80%) 

Urinary bladder (5) 

Calculus, microscopic observation only 1 (20%) 

(5) (5) (5) 

4 (80%) 5 (100%) 2 (40%) 

(5) (5) (5) 

Systems Examined With No Lesions Observed 

Alimentary System 

Cardiovascular System 

General Body System 

Integumentary System 

Musculoskeletal System 

Special Senses System 

2- Year Study 

Alimentary System 

Intestine large, colon (52) 

Inflammation,.chronic active 1 (2%) 

Mineralization 

Parasite metazoan 

Intestine large, rectum (52) 

Parasite metazoan 2 (4%) 

Intestine large, cecum (52) 

Parasite metazoan 

Liver (53) 

Angiectasis 

Basophilic focus 26 (49%) 

Clear cell focus 

Congestion 2 (4%) 

Cyst 1 (2%) 

Degeneration, cystic 

Eosinophilic focus 2 (4%) 

Fatty change 21 (40%) 

Fibrosis 

Granuloma 1 (2%) 

Hemorrhage 

Hepatodiaphragmatic nodule 7 (13 %) 

Inflammation, chronic 

Mixed cell focus 1 (2%) 

Pigmentation, bile 1 (2%) 

Pigmentation, hemosiderin 1 (2%) 

Thrombosis 

Bile duct, hyperplasia 4 (8%) 

Hepatocyte, hyperplasia 4 (8%) 

Hepatocyte, necrosis 6 (11%) 

Portal vein, thrombosis 

(53) (53) (54) 

2 (4%) 

(53) 

(53) 

(53) 

2 (4%) 

38 (72%) 

1 (2%) 

1 (2%) 

1 (2%) 

3 (6%) 

18 (34%) 

1 (2%) 

1 (2%) 

3 (6%) 

1 (2%) 

1 (2%) 

3 (6%) 

6 (11%) 

7 (13%) 

1 (2%) 

t (2%) 

(52) 

2 (4%) 

(53) 

1 (2%) 

(53) 

1 (2%) 

27 (51%) 

3 (6%) 

2 (4%) 

3 (6%) 

16 (30%) 

9 (17%) 

1 (2%) 

3 (6%) 

3 (6%) 

3 (6%) 

1 (2%) 

(54) 

5 (9%) 

(54) 

(54) 

1 (2%) 

34 (63%) 

1 (2%) 

2 (4%) 

15 (28%) 

4 (7%) 

1 (2%) 

1 (2%) 

1 (2%) 

8 (15%) 

4 (7%) 
210 Nickel Oxide, NTP TR 451 

TABLE B5 

Summary of the Incidence of Nonneoplastic Lesions in Female Rats in the 2-Year Inhalation Study of Nickel Oxide 

(continued) 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 

2-Year Study (continued) 

Alimentary System (continued 

Pancreas 

Atrophy 

Acinus, atrophy 

Artery, mineralization 

Stomach, forestomach 

Edema 

Hyperkeratosis 

Inflammation, chronic 

Inflammation, chronic active 

Mineralization 

Ulcer 

Stomach, glandular 

Erosion 

Mineralization 

Ulcer 

Tooth 

Inflammation, suppurative 

(52) (53) (53) (54) 

2 (4%) 1 (2%) 

1 (2%) 

(52) (53) 

1 (2%) 

1 (2%) 1 (2%) 

1 (2%) 

(52) 

(1) 

3 (6%) 

(53) 

1 (2%) 

1 (2%) 

1 (2%) 

(53) 

4 (8%) 

1 (2%) 

1 (2%) 

1 (2%) 

2 (4%) 

(53) 

1 (2%) 

1 (2%) 

(54) 

4 (7%) 

1 (2%) 

1 (2%) 

(54) 

(1) 

1 (100%) 

Cardiovascular System 

Blood vessel 

Aorta, mineralization 

Aorta, polyarteritis 

Mesenteric artery, polyarteritis 

Mesenteric artery, thrombosis 

Vena cava, mineralization 

Heart 

Inflammation, chronic 

Atrium, thrombosis 

Vein, inflammation, chronic acnve 

Ventricle, mineralization 

(3) 

(53) 

1 (2%) 

1 (2%) 

(1) 

1 (100%) 

1 (100%) 

1 (100%) 

(53) 

! (2%) 

(2) 

1 (50%) 

1 (50%) 

(53) 

1 (2%) 

1 (2%) 

(54) 

1 (2%) 

1 (2%) 

Endocrine System 

Adrenal cortex 

Angiectasis 

Atrophy 

Congestion 

Cyst 

Degeneration 

Degeneration, fatty 

Edema 

Hemorrhage 

Hyperplasia 

Bilateral, angiectasis 

Adrenal medulla 

Angiectasis 

Congestion 

Hyperplasia 

(53) 

1 (2%) 

1 (2%) 

1 (2%) 

I (2%) 

2 (4%) 

2 (4%) 

1 (2%) 

(51) 

3 (6%) 

8 (16%) 

(53) 

3 

2 

3 

1 

1 

(52) 

1 

1 

12 

(6%) 

(4%) 

(6%) 

(2%) 

(2%) 

(2%) 

(2%) 

(23 %) 

(53) 

3 (6%) 

2 (4%) 

5 (9%) 

1 (2%) 

1 (2%) 

1 (2%) 

(53) 

14 (26%) 

(54) 

4 (7%) 

8 (15%) 

1 (2%) 

(53) 

1 (2%) 

22 C42%) 
Lesions in Female Rats 211 

TABLE B5 

Summary of the Incidence of Nonneoplastic Lesions in Female Rats in the 2oyear Inhalation Study of Nickel Oxide 

(continued) 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m ~ 2.5 mg/m ~ 

2-Year Study (continued) 

Endocrine System (continued) 

Islets, pancreatic (52) 

Hyperplasia 

Parathyroid gland (47) 

Cyst 

Hyperplasia 

Pituitary gland (52) 

Angiectasis 1 (2%) 

Pars distalis, angiectasis 7 (13%) 

Pars distalis, cyst 8 (15%) 

Pars distalis, degeneration 

Pars distalis, hemorrhage 

Pars dismlis, hyperplasia 9 (17%) 

Pars intermedia,, angiectasis 

Pars intermedia, cyst 

Pars intermedia, hypertrophy 

Thyroid gland (52) 

C-cell, hyperplasia 

(53) (53) (54) 

1 (2%) 1 (2%) 

(47) (50) (50) 

1 (2%) 

1 (2%) 

(52) (52) (54) 

1 (2%) 

6 (12%) 6 (12%) 5 (9%) 

8 (15%) 11 (21%) 9 (17%) 

I (2%) 

2 (4%) 

11 (21%) 6 (12%) 12 (22%) 

1 (2%) ! (2%) 

I (2%) 

1 (2%) 

(52) (53) (53) 

3 (6%) 2 (4%) 

General Body System 

Tissue NOS 

Abscess 

(6) (1) (3) (3) 

1 (33%) 

Genital System 

Clitoral gland (53) (53) (51) (50) 

Atrophy 1 (2%) 

Ectasia 5 (9%) 3 (6%) 5 (10%) 4 (8%) 

Hyperplasia, cystic 1 (2%) 

Inflammation, chronic active 1 (2%) 

Inflammation, suppurative 1 (2%) 1 (2%) 

Duct, ectasia 1 (2%) 

Ovary (53) (53) (53) (54) 

Cyst 5 (9%) 5 (9%) 7 (13%) 3 (6%) 

Fibrosis 1 (2%) 

Hemorrhage 1 (2%) 

Bilateral, cyst I (2%) 

Uterus (53) (53) (52) (54) 

Cyst 1 (2%) 

Dilatation 1 (2%) I (2%) 

Prolapse 1 (2%) 

Endometrium, hyperplasia, cystic 5 (9%) 1 (2%) 2 (4%) 7 (13%) 

Hematopoietic System 

Bone marrow (52) 

Fibrosis 5 (10%) 

Hyperplasia 14 (27%) 

Necrosis 

(53) (53) (54) 

3 (6%) 3 (6%) l (2%) 

15 (28%) 15 (28%) 16 (30%) 

1 (2%) 
212 Nickel Oxide, NTP TR 451 

TABLE B5 

Summary of the Incidence of Nonneoplastic Lesions in Female Rats in the 2-Year Inhalation Study of Nickel Oxide 

(continued) 

0 mg/m a 0.62 mg/m 3 1.25 mg/m a 2.5 mg/m 3 

2-Year Study (continued) 

Hematopoietie System (continued) 

Lymph node (14) (6) 

Hyperplasia, lymphoid 1 (17%) 

Pigmentation 1 (7%) 

lliac, hyperplasia, lymphoid 1 (7%) 

Pancreatic, hyperplasia, lymphoid 

Pancreatic, inflammation, chronic active 1 (7%) 

Popliteal, pigmentation 1 (7 %) 

Renal, congestion 2 (33%) 

Renal, edema 

Renal, hyperplasia, lymphoid 

Renal, pigmentation 

Renal, pigmentation, hemosiderin 1 (7%) 

Lymph node, bronchial (49) (50) 

Congestion 2 (4%) 2 (4%) 

Edema 1 (2%) 

Hyperplasia, lymphoid 1 (2%) 5 (10%) 

Hyperplasia, macrophage 1 (2%) 

Pigmentation 43 (86%) 

Pigmentation, hemosiderin 1 (2 %) 

Lymph node, mandibular (47) (45) 

Congestion 1 (2%) 

Hyperplasia, lymphoid 3 (6%) 2 (4%) 

Pigmentation 2 (4%) 

Lymph node, mesenteric (51) (53) 

Congestion 1 (2%) 

Hyperplasia, lymphoid 

Inflammation, chronic active 1 (2%) 

Pigmentation 4 (8%) 2 (4%) 

Lymph node, mediastinal (48) (46) 

Congestion 1 (2%) 5 (11%) 

Ectasia 

Edema 

Hyperplasia, lymphoid 1 (2%) 9 (20%) 

Hyperplasia, plasma cell 1 (2%) 

Inflammation, chronic active 1 (2%) 

Pigmentation 34 (74%) 

Pigmentation, hemosiderin 

Spleen (53) (53) 

Fibrosis 1 (2%) 3 (6%) 

Hematopoietic cell proliferation 1 (2 %) 

Hemorrhage 

Hyperplasia 

Hyperplasia, lymphoid 

Infarct 1 (2%) 1 (2%) 

Necrosis 1 (2%) 

Capsule, fibrosis 

(9) (3) 

1 01%) 

1 (11%) 

(53) 

1 (2%) 

1 (2%) 

20 (38%) 

52 (98%) 

(51) 

3 (6%) 

(53) 

(48) 

7 (15%) 

1 (2%) 

1 (2%) 

14 (29%) 

1 (2%) 

39 (81%) 

t (2%) 

(53) 

3 (6%) 

1 (2%) 

1 (2%) 

1 (2%) 

1 (33%) 

1 (33%) 

(52) 

2 (4%) 

13 (25%) 

! (2%) 

47 (90%) 

(49) 

3 (6%) 

(54) 

3 (6%) 

3 (6%) 

(50) 

1 (2%) 

! (2%) 

14 (28%) 

44 (88%) 

(54) 

1 (2%) 

2 (4%) 
Lesions in Female Rats 213 

TABLE B5 

Summary of the Incidence of Nonneoplastic Lesions in Female Rats in the 2-Year Inhalation Study of Nickel Oxide 

(continued) 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m a 

2-Year Study (continued) 

Integumentary System 

Mammary gland 

Hyperplasia, glandular 

Skin 

Inflammation, suppurative 

Subcutaneous tissue, edema 

Subcutaneous tissue, fibrosis 

(53) (53) (53) (54) 

1 (2%) 

(4) (3) (3) (5) 

1 (33%) 

1 (33%) 

1 (33%) 

Musculoskeletal System 

Bone (53) (53) (53) 

Hyperostosis 2 (4%) 

Osteopetrosis 4 (8%) 2 (4%) 

Femur, hyperostosis 5 (9%) 2 (4%) 10 (19%) 

Skeletal muscle (1) 

Inflammation, chronic 1 (100%) 

(54) 

8 (15%) 

Nervous System 

Brain 

Hemorrhage 

Cerebellum, c~mpression 

Cerebrum, Compression 

Cerebrum, ventricle, dilatation 

Hypothalamus, compression 

Pons, compression 

Ventricle, dilatation 

(53) (53) (53) 

1 (2%) 

1 (2%) 

5 (9%) 4 (8%) 

2 (4%) 1 (2%) 

2 (4%) 1 (2%) 

1 (2%) 

3 (6%) 

2 (4%) 

3 (6%) 

1 (2%) 

1 (2%) 

(54) 

5 (9%) 

5 (9%) 

5 (9%) 

3 (6%) 

Respiratory System 

Larynx (53) (53) (53) 

Inflammation,, chronic 4 (8%) 2 

Inflammation, chronic active 3 (6%) 2 (4%) 2 

Inflammation, suppurative l (2%) 2 

Lung (53) (53) (53) 

Congestion 1 (2%) 1 

Cyst 

Hemorrhage 2 

Inflammation, chronic 18 (34%) 52 (98%) 53 

Inflammation, chronic active 1 (2%) 

Mineralization 1 

Alveolar epithelium, hyperplasia, atypical 1 (2%) 1 (2%) 6 

Alveolar epithelium, hyperplasia, focal 1 (2%) 

Alveolus, pigmentation 52 (98%) 53 

Pleura, fibrosis 1 

Nose (53) (53) (52) 

Inflammation, chronic 1 (2%) 

Inflammation, chronic active 1 (2%) 

Inflammation, suppurative 1 (2%) 2 

(4%) 

(4%) 

(4%) 

(2%) 

(4%) 

(100%) 

(2%) 

(11%) 

(100%) 

(2%) 

(4%) 

(54) 

3 

(54) 

1 

1 

2 

54 

5 

1 

54 

(54) 

1 

(6%) 

(2%) 

(2%) 

(4%) 

(100%) 

(9%) 

(2%) 

(100%) 

(2%) 
214 Nickel Oxide, NTP TR 451 

TABLE B5 

Summary of the Incidence of Nonneoplastic Lesions in Female Rats in the 2-Year Inhalation Study of Nickel Oxide 

(continued) 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 

2-Year Study (continued) 

Respiratory System (continued) 

Trachea 

Inflammation, chronic active 

Inflammation, suppurative 

(53) (53) (53) (54) 

2 (4%) 

2 (4%) 

Special Senses System 

Eye 

Cataract 

Hemorrhage 

Inflammation, suppurative 

Necrosis 

Synechia 

Bilateral, cornea, edema 

Cornea, edema 

Lens, cataract 

(3) 

1 (33%) 

1 (33%) 

1 (33%) 

1 (33%) 

(2) (5) 

2 (40%) 

1 (20%) 

1 (20%) 

2 (40%) 

(3) 

2 (67%) 

Urinary System 

Kidney 

Cyst 

Nephropathy 

Cortex, inflammation, chronic 

Cortex, necrosis, acute 

Pelvis, cyst 

Pelvis, dilatation 

Urinary bladder 

Calculus, microscopic observation only 

Edema 

(53) 

36 (68%) 

1 (2%) 

1 (2%) 

(52) 

(53) 

43 (81%) 

1 (2%) 

(53) 

(53) 

2 (4%) 

35 (66%) 

1 (2%) 

(53) 

1 (2%) 

1 (2%) 

(54) 

40 (74 %) 

1 (2%) 

(54). 
215 

APPENDIX C 

SUMMARY OF LESIONS IN MALE MICE 

IN THE 2-YEAR INHALATION STUDY 

OF NICKEL OXIDE 

TABLE C1 

TABLE C2 

TABLE C3 

TABLE C4a 

TABLE C4b 

TABLE C5 

Summary of the Incidence of Neoplasms in Male Mice 

in the 2-Year Inhalation Study of Nickel Oxide .......................... 216 

Individual Animal Tumor Pathology of Male Mice 

In the 2-Year Inhalation Study of Nickel Oxide .......................... 221 

Statistical Analysis of Primary Neoplasms in Male Mice 

in the 2-Year Inhalation Study of Nickel Oxide .......................... 248 

Historical Incidence of Alveolar/bronchiolar Neoplasms 

~n Untreated Male B6C3F~ Mice .................................... 251 

Historical Incidence of Hepatocellular Neoplasms 

~n Untreated Male B6C3F~ Mice .................................... 252 

Summary of the Incidence of Nonneoplastic Lesions in Male Mice 

~n the 2-Year Inhalation Study of Nickel Oxide .......................... 253 
216 Nickel Oxide, NTP TR 451 

TABLE C1 

Summary of the Incidence of Neoplasms in Male Mice in the 2-Year Inhalation Study of Nickel Oxide a 

0 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 5 mg/m 3 

Disposition Summary 

Animals initially in study 78 77 76 79 

7-Month interim evaluation 5 5 5 5 

15-Month interim evaluation 5 5 5 5 

Early deaths 

Accidental deaths b I0 

Moribund 23 26 26 29 

Natural deaths 15 18 11 17 

Survivors 

Terminal sacrifice 19 23 29 23 

Missexed 1 

Animals examined microscopically 67 77 76 79 

7-Month Interim Evaluation 

Alimentary System 

Liver (1) (2) 

Hepatocellular adenoma 1 (100%) 2 (100%) 

Respiratory System 

Lung (5) 

Alveolar/bronchiolar adenoma 1 (20%) 

(5) (5) (5) 

Systems Examined With No Neoplasms Observed 

Cardiovascular System 

Endocrine System 

General Body System 

Genital System 

Hematopoietic System 

Integumentary System 

Musculoskeletal System 

Nervous System 

Special Senses System 

Urinary System 

15-Month Interim Evaluation 

Alimentary System 

Liver (5) 

Hepatocellular carcinoma 1 (20 %) 

Hepatocellular adenoma 1 (20%) 

(5) 

1 (20%) 

1 (20%) 

(5) 

1 (20%) 

2 (40%) 

(5) 

Endocrine System 

Thyroid gland (5) 

Follicular cell adenoma 1 (20%) 

(5) (5) (5) 
Lesions in Male Mice 217 

TABLE C1 

Summary of the Incidence of Neoplasms in Male Mice in the 2-Year Inhalation Study of Nickel Oxide 

(continued) 

0 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 5 mg/m 3 

15-Month Interim Evaluation (continued) 

Respiratory System 

Lung (5) 

Alveolar/bronchiolar adenoma 1 (20%) 

Hepatocellular carcinoma, metastatic 1 (20%) 

(5) (5) (5) 

Systems Examined With No Neoplasms Observed 

Cardiovascular System 

General Body System 

Genital System 

Hematopoietic System 

Integumentary System 

Musculoskeletal System 

Nervous System 

Special Senses System 

Urinary System 

2- Year Study 

Alimentary System 

Esophagus (56) 

Squamous cell carcinoma 

Intestine large, colon (50) 

Intestine large, cecum (49) 

Intestine small, duodenum (51) 

Adenoma 

Intestine small, ileum (51) 

Liver (57) 

Alveolar/bronchiolar carcinoma, metastatic, 

lung 

Hemangiosarcoma 1 

Hemangiosarcoma, multiple 

Hepatocellular carcinoma 6 

Hepatocellular carcinoma, multiple 

Hepatoce!lular adenoma 7 

Hepatocellular adenoma, multiple 1 

Hepatocholangiocarcinoma 

Histiocytic sarcoma 

Mesentery (1) 

Lipoma 1 

Salivary glands (57) 

Stomach, forestomach (54) 

Squamous cell papilloma 1 

Tooth (2) 

Odontoma 

(2%) 

(II%) 

(12%) 

(2%) 

(100%) 

(2%) 

(67) 

1 (1%) 

(61) 

(56) 

(53) 

(49) 

(67) 

1 (1%) 

13 (19%) 

3 (4%) 

5 (7%) 

(1) 

(67) 

(63) 

1 (2%) 

(5) 

1 (20%) 

(66) (69) 

(60) (62) 

(60) (60) 

(56) (58) 

1 (2%) 

(55) (57) 

(66) (69) 

8 (12%) 

3 (5%) 

11 (17%) 

2 (3%) 

(66) 

(65) 

(4) 

2 (50%) 

1 (1%) 

2 (3%) 

13 (19%) 

2 (3%) 

9 (13%) 

1 (1%) 

I (1%) 

(69) 

(67) 

1 (1%) 

(1) 

1 (100%) 
218 Nickel Oxide, NTP TR 451 

TABLE C1 

Summary of the Incidence of Neoplasms in Male Mice in the 2-Year Inhalation Study of Nickel Oxide 

(continued) 

0 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 5 mg/m 3 

2-Year Study (continued) 

Cardiovascular System 

Heart 

Alvcolar/bronchiolar carcinoma, metastatic, 

lung 

Hepatocholangiocarcinoma, metastatic, liver 

(57) (67) (66) (69) 

I (I %) 

I (1%) 

Endocrine System 

Adrenal cortex 

Adenoma 

Capsule, adenoma 

Islets, pancreatic 

Adenoma 

Thyroid gland 

Bilateral, follicular cell, adenoma 

Follicular cell, adenoma 

(57) (67) (65) (69) 

2 (4%) 1 (1%) 

2 (4%) 1 (2%) 

(54) (64) (66) (68) 

1 (2%) 

(55) (67) (66) (69) 

2 (3%) 

2 (4%) 2 (3%) 2 (3%) 

General Body System 

Tissue NOS 

Alveolar/bronchiolar carcinoma, metastatic, 

lung 

Hemangiosarcoma 

Hepatocholangiocarcinoma, metastatic, liver 

Lipoma 

Sarcoma 

(2) 

1 (50%) 

(3) 

1 (33%) 

(4) 

1 (25%) 

1 (25%) 

1 (25%) 

Genital System 

Epididymis 

Sarcoma 

Prostate 

Testes 

Interstitial cell, adenoma 

(56) (67) 

1 (2%) 

(53) (61) 

(57) (66) 

(66) 

(63) 

(66) 

2 (3%) 

(68) 

(65) 

(69) 

l-Iematopoietie System 

Bone marrow (56) 

Hemangiosarcoma, metastatic 1 (2%) 

Lymph node (22) 

Axillary, alveolar/bronchiolar carcinoma, 

metastatic, lung 

Lymph node, bronchial (45) 

Hepatocholangiocarcinoma, metastatic, liver 

Lymph node, mandibular (47) 

Lymph node, mesenteric (45). 

Hepatocholangiocarcinoma, metastatic, liver 

Lymph node, mediastinal (18) 

Hemangiosarcoma, metastatic 

(66) 

(18) 

(56) 

(57) 

(55) 

(19) 

(66) 

(20) 

(61) 

(63) 

(56) 

(21) 

1 (5%) 

(68) 

(16) 

1 (6%) 

(62) 

1 (2%) 

(60) 

(63) 

1 (2%) 

(25) 
Lesions in Male Mice 219 

TABLE C1 

Summary of the Incidence of Neoplasms in Male Mice in the 2-Year Inhalation Study of Nickel Oxide 

(continued) 

0 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 5 mg/m 3 

2-Year Study (continued) 

Hematopoietic System (continued) 

Spleen 

Hemangioma 

Hemangiosarcoma 

Histiocytic sarcoma 

Thymus 

Alveolar/bronchiolar carcinoma, metastatic, 

lung 

Hepatocholangiocarcinoma, metastatic, liver 

Histiocytic sarcoma 

(56) (67) (66) (69) 

1 (1%) 

1 (2%) 1 (1%) 2 (3%) 1 (1%) 

1 (1%) 

(45) (53) (52) (58) 

1 (2%) 

1 (2%) 

1 (2%) 

Integumentary System 

Skin 

Hamartoma 

Subcutaneous tissue, hemangioma 

(16) (23) (24) (27) 

1 (4%) 

1 (4%) 

Musculoskeletal System 

Bone 

Hemangiosarcoma, metastatic 

(57) (67) (66) (68) 

1 (2%) 

Nervous System 

None 

Respiratory System 

Lung (57) 

Alveolar/bronchiolar adenoma 7 (12 %) 

Alveolar/bronchiolar carcinoma 4 (7 %) 

Alveolar/bronchiolar carcinoma, multiple 

Hepatocellular carcinoma, metastatic 

Hepatocellular carcinoma, metastatic, liver 

Hepatocholangiocarcinoma, metastatic, liver 

Histiocytic sarcoma 

Nose (55) 

(67) (66) (69) 

5 (7%) 6 (9%) 11 (16%) 

9 (13%) 9 (14%) 5 (7%) 

1 (1%) 1 (1%) 

I (1%) 3 (5%) 4 (6%) 

1 (1%) 

(66) (66) 

1 (1%) 

1 (1%) 

(67) 

Special Senses System 

Harderian gland 

Adenoma 

(1) (2) (3) 

1 (lO0%) 2 (100%) 2 (67%) 

Urinary System 

Kidney (57) 

Urinary bladder (54) 

Transitional epithelium, papilloma 

(67) (66) (68) 

(63) (65) (66) 

1 (2%) 
220 Nickel Oxide, NTP TR 451 

TABLE C1 

Summary of the Incidence of Neoplasms in Male Mice in the 2-Year Inhalation Study of Nickel Oxide 

(continued) 

0 mg/m a 1.25 mg/m 3 2.5 mg/m 3 5 mg/m 3 

2-Year Study (continued) 

Systemic Lesions 

Multiple organs c (57) (67) (66) (69) 

Histiocytic sarcoma 1 (1%) 

Lymphoma malignant 2 (4%) 2 (3%) 2 (3%) 5 (7%) 

Neoplasm Summary 

Total animals with primary neoplasms ct 

7-Month interim evaluation 2 2 

15-Month interim evaluation 3 2 3 

2-Year study 29 37 40 44 

Total primary neoplasms 

7-Month interim evaluation 2 2 

15-Month interim evaluation 4 2 3 

2~Year study 39 49 55 60 

Total animals with benign neoplasms 

7-Month interim evaluation 2 2 

15-Month interim evaluation 2 1 2 

2-Year study 18 16 25 26 

Total benign neoplasms 

7-Month interim evaluation 2 2 

15-Month interim evaluation 3 1 2 

2-Year study 23 18 31 28 

Total animals with malignant neoplasms 

15-Month interim evaluation 1 1 1 

2-Year study 15 28 22 30 

Total malignant neoplasms 

15-Month interim evaluation 1 1 I 

2-Year study , 16 31 24 32 

Total animals with metastatic neoplasms 

15-Month int~ ~m evaluation 1 

2-Year study 1 2 4 6 

Total metastatic neoplasms 

15-Month interim evaluation 1 

2-Year study 2 2 4 15 

a Number of animals examined microscopically at the site and the number of animals with neoplasm 

b No histopathologic examination was performed on these animals. 

c Number of animals with any tissue examined microscopically 

d Primary neoplasms: all neoplasms except metastatic neoplasms 
Lesions in Male Mice 221 

TABLE C2 

Individual Animal Tumor Pathology of Male Mice in the 2-Year Inhalation Study of Nickel Oxide: 0 mg/m 3 

Number of Days on Study 

0111233445555555555666666 

0666949370115558999000022 

4222012008029994039123799 

Carcass ID Number 

0000000000000000000000000 

6222043232110150531614155 

5589831261509445392385907 

Alimentary System 

Esophagus 

Gallbladder 

Intestine large, colon 

Intestine large, rectum 

Intestine large, cecum 

Intestine small, duodenum 

Intestine small, jejunum 

Intestine small, ileum 

Liver 

Hemangiosarcoma 

Hepatocellular carcinoma 

Hepatocellular adenoma 

Hepatocellular adenoma, multiple 

Mesentery 

Lipoma 

Pancreas 

Salivary glands 

Stomach, forestomach 

Squamous cell papilloma 

Stomach, glandu'lar 

Tooth 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

A +AA +MA +MA + + + +MAA + + + + + + + + 

A +A ++A + + + ++ + + +AAA + +~+ + + + + 

AMA + +A + + + + + + + +AAA + +A + + + +M 

A +A + +A +++ + + + + +AAA + +A + + + + + 

A + + + +A + + + + + + + +AAA + +A + + + + + 

A + + + +A + + + + + + + +AAA + +A + + + + + 

A + + + +A + + ++ + + + +AAA + +A + ++ ++ 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

X X X 

M+ + + + + + + + + + + + + +A + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + +M+ + + + + + + + + + +A + + +A + + + + + 

+ ++++++ ++++ + + ++A ++ +A ++ + + + 

+ 

Cardiovascular System 

Heart + + + + + + + + + + + + + + + + + + + + + + + + + 

Endocrine System 

Adrenal cortex + + + + + + + + + + + + + + + + + + + + + + + + + 

Adenoma 

Capsule, adenoma 

Adrenal medulla 

Islets, pancreatic 

Parathyroid gland 

Pituitary gland 

Thyroid gland 

Follicular, cell, adenoma 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

M+ + + + + + + + + + + + + +A + + + + + + + + + 

MMMMM+M+MMMMMMMA +M+++ ++ ++ 

++M++ + +++ +++ + + + + + + +++ ++ ++ 

M++++ +++ +++ + + + +A + + +++ ++ ++ 

X 

General Body System 

Tissue NOS 

Hemangiosarcoma 

Genital System 

Epididymis 

Sarcoma 

Penis 

Preputial gland 

Prostate 

Seminal vesicle 

Testes 

+ + + + + + ÷ ~ + + + + ÷ + + + + + + + ÷ + + + + 

X 

+ +÷ + 

+ + ÷ + + + + + + + + + + ÷ ÷ + + ÷ + + + + + W ÷ 

MM+++M+++++ + ++++++ + ++ + + + + 

+ + + + +A + + + + + + + + +A + + + + + + + + + 

+ + + + + + + + + + + + + + + ÷ + + + + + + + + + 

+: Tissue examined microscopically M: Missing tissue X: Lesion present 

A: Autolysis precludes examination I: Insufficient tissue Blank: Not examined 
222 Nickel Oxide, NTP TR 451 

TABLE C2 

Individual Animal Tumor Pathology of Male Mice in the 2-Year Inhalation Study of Nickel Oxide: 0 mg/m ~ (continued) 

Number of Days on Study 

6666666666777777777777777 

3445667899113333333333333 

7333065947332777777788888 

Carcass ID Number 

0000000000000000000000000 

0576010342464003344601223 

2202134486182372567066047 

Alimentary System 

Esophagus 

Gallbladder 

Intestine large, colon 

Intestine large, rectum 

Intestine large, cecum 

Intestine small, duodenum 

Intestine small, jejunum 

Intestine small, ileum 

Liver 

Hemangiosareoma 

Hepatocellular carcinoma 

Hepatocellular adenoma 

Hepatocellular adenoma, multiple 

Mesentery 

Lipoma 

Pancreas 

Salivary glands 

Stomach, forestornach 

Squamous cell papilloma 

Stomach, glandular 

Tooth 

+++++++++ 

+++++++++ 

+++++++++ 

+M+++++++ 

+++M+++++ 

+++++++++ 

+++++++++ 

+++++++++ 

+++++++++ 

+ + + + + + + + + + M + + + + + 

+ + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + 

+ + + + +M+ + + + + +M+ + + 

+ + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + 

+ + i + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + 

X X X 

X XX X X 

X 

+ 

X 

+ + +i + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

Cardiovascular System 

Hea~ + + + + + + + + + + + + + + + + + + + + + + + + + 

Endocrine System 

Adrenal cortex 

Adenoma 

Capsule, adenoma 

Adrenal medulla 

Islets, pancreatic 

Parathyroid gland 

Pituitary gland 

Thyroid gland 

Follicular cell, adenoma 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + +M + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + +M+ + + +MM+ + +M+ 

+ + + ~ + + + + + + + + + + + + + + + + + + + + + 

+ + ++ ~ + + + + + + + + + + + + + + + + + + + + 

X 

General Body System 

Tissue NOS 

Hemangiosareoma 

+ 

X 

Genital System 

Epididymis 

Sarcoma 

Penis 

Preputial gland 

Prostate 

Seminal vesicle 

Testes 

+ + + + + + + + + + + + + + + + + M + + + + + + + 

++ + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

++++++ + ++M++++ ++++ + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + +.+ + + + + + + + + + + + + + + • 
Lesions in Male Mice 223 

TABLE C2 

Individual Animal Tumor Pathology of Male Mice in the 2-Yeear Inhalation Study of Nickel Oxide: 0 mg/m 3 (continued) 

Number of Days on Study 

7777777 

3333333 

8899999 

Carcass ID Number 

13 0 0 0 13 0 0 Total 

3 6 3 3 6 6 6 Tissues/ 

8 1 0 3 4 6 7 Tumors 

Alimentary System 

Esophagus + + + + + + + 56 

Gallbladder + + + + + + + 47 

Intestine large, colon + + + + + + + 50 

Intestine large, rectum + + + + + + + 45 

Intestine large, cecum + + + + + + + 49 

Intestine small, duodenum + + + + + + + 51 

Intestine small, jejunum + + + + + + + 50 

Intestine small, ileum + + + + + + + 51 

Liver + + + + + + + 57 

Hemangiosarcoma 1 

Hepatocellular carcinoma 6 

Hepatocellular adenoma X 7 

Hepatocellular adenoma, multiple 1 

Mesenteqt 1 

Lipoma 1 

Pancreas + + + + + + + 54 

Salivary glands + + + + + + + 57 

Stomach, forestomach + + + + + + + 54 

Squamous cell papilloma 1 

Stomach, glandular + + + + + + + 55 

Tooth + 2 

Cardiovascular System 

Hea~ + + + + + + + 57 

Endocrine System 

Adrenal cortex + + + + + + + 57 

Adenoma X 2 

Capsule, adenoma X 2 

Adrenal medulla + + + + + + + 57 

Islets, pancreatic + + + + + + + 54 

Parathyroid gland + + + + + M + 37 

Pituitary gland + + + + + + + 56 

Thyroid gland + + + + + + + 55 

Follicular cell, adenoma 2 

General Body System 

Tissue NOS + 2 

Hemangiosarcoma 1 

Genital System 

Epididymis + + + + + + + 56 

Sarcoma 1 

Penis 7 

Preputial gland + + + + + + + 57 

Prostate + + + + + + + 53 

Seminal vesicle + + + + + + + 55 

Testes + + + + + + + 57 
224 Nickel Oxide, NTP TR 451 

TABLE C2 

Individual Animal Tumor Pathology of Male Mice in the 2-Year Inhalation Study of Nickel Oxide: 0 mg/m 3 (continued) 

Number of Days on Study 

0111233445555555555666666 

06669'49370115558999000022 

4222012008029994039123799 

Carcass ID Number 

0000000000000000000000000 

6222043232110150531614155 

5589831261509445392385907 

Hematopoietic System 

Bone marrow 

Hemangiosarcoma, metastatic 

Lymph node 

Lymph node, bronchial 

Lymph node, mandibular 

Lymph node, mesenteric 

Lymph node, mediastinal 

Spleen 

Hemangiosarcoma 

Thymus 

+ + + + + + + + + + + + + + +A + + + + + + + + + 

+ + +++ + +++ ++ 

+ + + +I M+ +I + + + + + +MI +M+ + + + + + 

M+ + + + + +MM+ + + + + +A + + + + + +M+ + 

MMMMM+ + + + + + + + + +MI + + + + + + +M 

MMMMMM+M+ + +MMM+MM+M+M+MMM 

+ + + + + + + + + + + + + + +M+ + + + + + + + + 

+ + + + + +M+ + + + + + + +MI + + +M+M+ + 

Integumentary System 

Mammary gland 

Skin 

+ + + + + + + + + + + + + + + + + + + +M+ + + + 

+ +++++ ++++ 

Musculoskeletai System 

Bone 

Hemangiosarcoma, metastatic 

Skeletal muscle 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

Nervous System 

Brain + + + + + + + + + + + + + + + + + + + + + + + + + 

Respiratory System 

Larynx 

Lung 

Alveolar/bronchiolar adenoma 

Alveolar/bronehiolar carcinoma 

Nose 

Trachea 

+ +M++ + ++ + + + + + +I ++ + + + ++ + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

X 

A + + + + + + + + + + + + + +A + + + + + + + + + 

+ + I + + + + + + + + + + + + + + + + + + + + + + 

Special Senses System 

None 

Urinary System 

Kidney 

Urethra 

Urinary bladder 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

A + + + +M+ ++ + + + + + + + + + + + + + + + + 

Systemic Lesions 

Multiple organs 

Lymphoma malignant X 
Lesions in Male Mice 225 

TABLE C2 

Individual Animal Tumor Pathology of Male Mice in the 2-Year Inhalation Study of Nickel Oxide: 0 mg/m 3 (continued) 

Number of Days on Study 

6666666666777777777777777 

3445667899113333333333333 

7333065947332777777788888 

Carcass ID Number 

0000000000000000000000000 

0576010342464003344601223 

2202134486182372567066047 

Hematopoietic System 

Bone marrow 

Hemangiosarcoma, metastatic 

Lymph node 

Lymph node, bronchial 

Lymph node, mandibular 

Lymph node, mesenteric 

Lymph node, mediastinal 

Spleen 

Hemangiosarcoma 

Thymus 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

+ ++++++ + + ."+ 

+ + +M+ + + + +I + + + + + + + +M+ + + + + + 

+M+ + + + + + + + + + + ++M+ + + + + +M+M 

+ + + + + + +M+ + + +M+ + + + + + + + + + + + 

+MMMMMMMM+M+MM+M+MI M+I MMM 

+ + + + + + + + + + + + + ++++ + + + + + ++ + 

X 

+M+M+M+ + + +M+ + + +MM+ + +M+ + + + 

Integumentary System 

Mammary gland 

Skin 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ ++ + + + 

Muscuioskeletal System 

Bone 

Hemangiosarcoma, metastatic 

Skeletal muscle 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

+ 

Nervous System 

Bmin + + + + + + + + + + + + + + + + + + + + + + + + + 

Respiratory System 

Larynx 

Lung 

Alveolar/bronchiolar adenoma 

Alveolar/bronchiolar carcinoma 

Nose 

Trachea 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X X X X X 

X X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

Special Senses System 

None 

Urinary System 

Kidney 

Urethra 

Urinary bladder 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ 

+ + + + + + + + + + + + + + + + + + + +M+ + + + 

Systemic Lesions 

Multiple organs 

Lymphoma malignant X 
226 Nickel Oxide, NTP TR 451 

TABLE C2 

Individual Animal Tumor Pathology of Male Mice in the 2-Year Inhalation Study of Nickel Oxide: 0 mg/m 3 (continued) 

Number of Days on Study 

7777777 

3333333 

8899999 

Carcass ID Number 

0 0 0 0 0 0 0 Total 

3 6 3 3 6 6 6 Tissues/ 

8 1 0 3 4 6 7 Tumors 

Hematopoietic System 

Bone marrow + + + + + + + 56 

Hemangiosarcoma, metastatic 1 

Lymph node + 22 

Lymph node, bronchial I + + M + + I 45 

Lymph node, mandibular + + + + + M + 47 

Lymph node, mesenteric + + + + + M M 45 

Lymph node, mediastinal + + M M + M + 18 

Spleen + + + + + + + 56 

Hemangiosarcoma 1 

Thymus + + + + + + + 45 

Integumentary System 

Mammary gland + + + + + + + 56 

Skin 16 

Musculoskeletal System 

Bone + + + + + + + 57 

Hemangiosarcoma, metastatic 1 

Skeletal muscle 1 

Nervous System 

Brain + + + + + + + 57 

Respiratory System 

Larynx + + + + + + + 55 

Lung + + + + + + + 57 

Alveolar/bronchiolar adenoma X 7 

Alveolar/bronchiolar carcinoma X 4 

Nose + + + + + + + 55 

Trachea + + + + +,+ + 56 

Special Senses System 

None 

Urinary System 

Kidney + + + + + + + 57 

Urethra + 2 

Urinary bladder + + + + + + + 54 

Systemic Lesions 

Multiple organs + + + + + + + .~ 57 

Lymphoma malignant 2 
Lesions in Male Mice 227 

TABLE C2 

Individual Animal Tumor Pathology of Male Mice in the 2-Year Inhalation Study of Nickel Oxide: 1.25 mg/m 3 

Number of Days on Study 

0111222344444555555556666 

2035299444789001335690111 

4557608125103182997734022 

Carcass ID Number 

111122212222212.1221222212 

9899102741211836138000061 

0019261406384598302902397 

Alimentary System 

Esophagus 

Squamous cell carcinoma 

Gallbladder 

Intestine large, colon 

Intestine large, rectum 

Intestine large, cecum 

Intestine small, duodenum 

Intestine small, jejunum 

Intestine small, ileum 

Liver 

Hemangiosarcoma, multiple 

Hepatocellular carcinoma 

Hepatocellular carcinoma, multiple 

Hepatocellular adenoma 

Mesentery 

Pancreas 

Salivary glands 

Stomach, forestomach 

Squamous cell papilloma 

Stomach, glandular 

Tooth 

Odontoma 

+ + + + + + + + ++ + + + + + + + + + + + + + + + 

+AAA +++A +AA +++A + + + +++ +A ++ 

+AA + + + + +A + + + + +A + + + + + + +A + + 

MAA ++ ++MAMMA +MA + + + +M+ + + + + 

+AAM+ + + +A + +A + +AA + + + + + +A + + 

MAA + + + +AAAAA + +AA + + + + + +A + + 

MAAM+ + +AAAAA + +A + + + + + + +A + + 

MAAM+ + +AAAAA + +AA + + + + + +A + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X X X X X 

X 

++M+++++M+++++++ + + + ++ + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

++A ++++ +A + + ++ A + + + + + + + + + + 

+ +A + + + + +A + + + + A + + + + + + + + + + 

Cardiovascular System 

Heart + + + + + + + + + + + + + + + + + + + + + + + + + 

Endocrine System 

Adrenal cortex 

Adrenal medulla 

Islets, pancreatic 

Parathyroid gland 

Pituitary gland 

Thyroid gland 

Bilateral, follicular cell, adenoma 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ +M+ + + + +M+ + + + + + + + + + + + + + + + 

MMMMMMM+ +MM+MM+ + + + + + + + + + + 

+ + + + +I M+ + + + + + + + + + + + + +M+M+ 

+++ ++ + +++ ++ ++++++ + + ++ + + + + 

General Body System 

None 

Genital System 

Epididymis 

Penis 

Preputial gland 

Prostate 

Seminal vesicle 

Testes 

+ + + +M+ + +M+ +M+ + +M+ + +M+ + + + + 

+ ÷ + + + + + + A + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + 
228 Nickel Oxide, NTP TR 451 

TABLE C2 

Individual Animal Tumor Pathology of Male Mice in the 2-Year Inhalation Study of Nickel Oxide: 1.25 mg/m 3 

(continued) 

Number of Days on Study 

6666666666666777777777777 

1234446777899011222333333 

6673499569324677668778888 

Carcass ID Number 

1121121112221212222121111 

8629927873037293133626677 

7262655924133841085391668 

Alimentary System 

Esophagus 

Squamous cell carcinoma 

Gallbladder 

Intestine large, colon 

Intestine large, rectum 

Intestine large, cecum 

Intestine small, duodenum 

Intestine small, jejunum 

Intestine small, ileum 

Liver 

Hemangiosarcoma, multiple 

Hepatocellular carcinoma 

Hepatocellular carcinoma, multiple 

Hepatocellular adenoma 

Mesentery 

Pancreas 

Salivary glands 

Stomach, forestomach 

Squamous cell papilloma 

Stomach, glandular 

Tooth 

Odontoma 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+A + + + + + +MA + +A + + + + + + + + + + + + 

+ + + + + + + + +A + + + + + + + + + + + + + + + 

+ + + + + + +MMA + + + + + + + + + + + + + +M 

++ + + +++M+A + + +A + + ++ + + + + + + + 

++++++ +A +A + + +A ++ + + ++ + + + + + 

+ + + + + + +A +A + + +A + + + + + + + + + + + 

+ ++++ + +AAA + + +A +++ + ++ ++ + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

X XX X X X X 

X X 

X X X 

+ 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + 

CardiovascularSystem 

Heaa + + + + + + + + + + + + + + + + + + + + + + + + + 

Endocrine System 

Adrenal cortex 

Adrenal medulla 

Islets, pancreatic 

Parathyroid gland 

Pituitary gland 

Thyroid gland 

Bilateral, follicular cell, adenoma 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + M+ 

+ + +M+ + + + +M+ + + + + +M+ + + + + + + + 

+ + + + + + + + + M+ + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

General Body System 

None 

Genital System 

Epididymis 

Penis 

Preputial gland 

Prostate 

Seminal vesicle 

Testes 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

++ + + ++ 

+ + + +M+ + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 
Lesions in Male Mice 229 

TABLE C2 

Individual Animal Tumor Pathology of Male Mice in the 2-Year Inhalation Study of Nickel Oxide: 1.25 mg/m 3 

(continued) 

Number of Days on Study 

7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 

3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 

8 8 8 8 8 8 8 9 9 9 9 9 9 9 9 9 9 

Carcass ID Number 

1 1 1 2 2 2 2 1 1 1 1 1 l 2 2 2 2 

8 8 9 0 1 3 3 6 6 7 7 8 8 0 2 2 2 

4 6 5 5 9 6 7 4 5 7 9 3 8 4 0 2 4 

Tetal 

Tissues/ 

Tumors 

Alimentary System 

Esophagus + + + + + + + + + + + + + + + + + 67 

Squamous cell carcinoma X 1 

Gallbladder + + + + + + + + + + + + + + + + + 55 

Intestine large, colon + + + + + + + + + + + + + + + + + 61 

Intestine large,~ectum + M + + + + + M + + M + + + + + M 48 

Intestine large, cecum + + + + + + + + + + + + + + + + + 56 

Intestine small, duodenum + + + + + + + + + + + + + + + + + 53 

Intestine small, jejunum + + + + + + + + + + + + + + + + + 53 

Intestine small, i~eum + + + + + + + + + M + + + + + M + 49 

Liver + + + + + + + + + + + + + + + + + 67 

Hemangiosarcoma, multiple 1 

Hepatocellular carcinoma X 13 

Hepatocellular carcinoma, multiple 3 

Hepatocellular adenoma X X 5 

Mesentery 1 

Pancreas + + + + + + + + + + + + + + + + + 65 

Salivary glands + + + + + + + + + + + + + + + + + 67 

Stomach, forestomach + + + + + + + + + + + + + + + + + 63 

Squamous ceil papilloma 1 

Stomach, glandular + + + + + + + + + + + + + + + -~ + 63 

Tooth + + + 5 

Odontoma X 1 

Cardiovascular System 

Heart + + + + + + + + + + + + + + + + + 67 

Endocrine System 

Adrenal cortex + + + + + + + + + + + + + + + + + 67 

Adrenal medulla + + + + + + + + + + + + + + + + + 67 

Islets, pancreatic + + + + + + + + + + + + + + + + + 64 

Parathyroid gland + M + M + + + + + M + M M + + + + 48 

Pituitary gland + + + + + + + + + + + + + + + + + ~2 

Thyroid gland + + + + + + + + + + + + + + + + + ~7 

Bilateral; follicular cell, adenoma X X 2 

General Body System 

Note 

Genital System 

Epididymis + + + + + + + ÷ + + + + + + + + + 67 

Penis 11 

Preputial gland + + + + + + + + + + + + + + + + + 66 

Prostate + + + + + + + + + M + + + + + + + 61 

Seminal vesicle + + + + + + + + + + + + + + + + + 66 

Testes + + + + + + + + + + + + + + + + + 66 
230 Nickel Oxide, NTP TR 451 

TABLE C2 

Individual Animal Tumor Pathology of Male Mice in the 2-Year Inhalation Study of Nickel Oxide: 1.25 mg/m 3 

(condnued) 

Number of Days on Study 

0111222344444555555556666 

2035299444789001335690111 

45576081251031.82997734022 

Carcass ID Number 

1111222122222121221222212 

9899102741211836138000061 

0019261406384598302902397 

Hematopoietic System 

Bone marrow 

Lymph node 

Lymph node, bronchial 

Lymph node, mandibular 

Lymph node, mesenteric 

Lymph node, mediastinal 

Spleen 

Hemangiosarcoma 

Thymus 

+ + +I + + + + + + + + + + + + + + + + + + + + + 

++ + ++ +++ ++ + 

MI M+M++M+++++++ +++M+ ++ + + + 

M+ + + + + + + + + + + + + +MM+ + + + +MM+ 

MMM+ +M+ +MM+ + + + +M+ + + + + + + + + 

MMMMMMM + MMMMMMMMM + MM + MM + I 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

+ +I + + + + +M+ + + + + + + + + + + + +I M+ 

Integumentary System 

Mammary gland 

Skin 

Hamartoma 

Subcutaneous tissue, hemangioma 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

++ + ++++ ++ 

Musculoske~talSystem 

Bone + + + + + + + + + + + + + + + + + + + + + + + + + 

Ne~ousSystem 

Brain + + + + + + + + + + + + + + + + + + + + + + + + + 

Respiratory System 

Larynx 

Lung 

Alveolar/bronchiolar adenoma 

Alveolar/bronchiolar carcinoma 

Alveolar/bronchiolar carcinoma, multiple 

Hepatocellular carcinoma, metastatic 

Hepatocellular carcinoma, metastatic, liver 

Nose 

Trachea 

Special Senses System 

Harderian gland 

Adenoma 

++ + +M++++M+ + ++++ ++ ++ ++ +++ 

+ + + + + + + + + + + + + + + + + + + + + + + ~ + 

x 

+ + + + + + + + + + + W + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

.~ 

Urinary System 

Kidney 

Urethra 

Urinary bladder 

Transitional epithelium, papilloma 

+ + +'+ + + + + + + + + ~ + + + + + + + + + + + + 

+ + 

+A + + + + + +A + + + + +A + + + + + + + + + + 

X 

Systemic Lesions 

Multiple organs 

Lymphoma malignant X 
Lesions in Male Mice 231 

TABLE C2 

Individual Animal Tumor Pathology of Male Mice in the 2-Year Inhalation Study of Nickel Oxide: 1.25 mg/m 3 

(continued) 

Number of Days on Study 

6666666666666777777777777 

1234446777899011222333333 

6673499569324677668778888 

Carcass ID Number 

1121121112221212222121111 

862992787303729 J 133626677 

7262655924133841085391668 

Hematopoietic System 

Bone marrow 

Lymph node 

Lymph node, bronchial 

Lymph node, mandibular 

Lymph node, mcsenteric 

Lymph node, mediastinal 

Spleen 

Hemangiosarcoma 

Thymus 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

++ ++ + + + 

+ + + + + + +M+M+ + + + +M+ + + + + + + + + 

+ +M+ + +M+ +M+ + +M+ + + + + + + + + + + 

++++M++++M+ ++++M+++ + +++ ++ 

MMM + + + + + MMMM + MMM + MM + M + MM + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + +M+ + + +M+MI + +I + +MI + + + + + + 

Integumentary. System 

Mammary gland 

Skin 

Hamartoma 

Subcutaneous tissue, hemangioma 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

++ ++++++ +++ + + + 

X 

X 

MusculoskeletalSystem 

Bone + + + + + + + + + + + + + + + + + + + + + + + + + 

NervousSystem 

B~in + + + + + + + + + + + + + + + + + + + + + + + + + 

Respiratory System 

Larynx 

Lung 

Alveolar/bronchiolar adenoma 

Alveolar/bronchiolar carcinoma 

Alveolar/bronchiolar carcinoma, multiple 

Hepatocellular carcinoma, metastatic 

Hepatocellular carcinoma, metastatic, liver 

Nose 

Trachea 

+ + + + + + + + + + + + + + I + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X X 

X X X X X X X 

X 

X 

+ +++ +++++A +++ + + + + + + ++ + ++ + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

Special Senses System 

Harderian gland 

Adenoma 

+ 

X 

Urinary System 

Kidney 

Urethra 

Urinary bladder 

Transitional epithelium, papilloma 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + +A + + + + + + + + + + + + + + + 

Systemic Lesions 

Multiple organs 

Lymphoma malignant X 
232 Nickel Oxide, NTP TR 451 

TABLE C2 

Individual Animal Tumor Pathology of Male Mice in the 2-Year Inhalation Study of Nickel Oxide: 1.25 mg/m 3 

(continued) 

Number of Days on Study 

77777777777777777 

33333333333333333 

88888889999999999 

Carcass ID Number 

11122221111112222 

88901336677880222 

46559674579384024 

Total 

Tissues/ 

Tumors 

Hematopoietic System 

Bone marrow + + + + + + + + + + + + + + + + + 66 

Lymph node 18 

Lymph node, bronchial + + + + + + + + + + + + M + + + M 56 

Lymph node, mandibular + + + + + + + + + + + + M + + + + 57 

Lymph node, mesenteric + + M M + + + + + + + + + + + + + 55 

Lymph node, mediastinal I M M M M M + + M M M + M M + M + 19 

Spleen + + + + + + + + + + + + + + + + + 67 

Hemangiosarcoma 1 

Thymus + + + I + + + + + + + + + + + M M 53 

Integumentary System 

Mammary gland + + + + + + + + + + + + + + + + + 67 

Skin 23 

Hamartoma 1 

Subcutaneous tissue, hemangioma 1 

Musculoskeletal System 

Bone + + + + + + + + + + + + + + + + + 67 

Nervous System 

Bmin + + + + + + + + + + + + + + + + + 67 

Respiratory System 

Larynx + + + + + + + + + + + + + + + + + 64 

Lung + + + + + + + + + + + + + + + + + 67 

Alveolar/bronchiolar adenoma X X 5 

Alveolar/bron~hiolar carcinoma X X 9 

Alveolar/bror ~fiolar carcinoma, multiple X 1 

Hepatocellular carcinoma, metastatic 1 

Hepatocellular carcinoma, metastatic, liver I 

Nose + + + + + + + + + + + + + + + + + 66 

Trachea + + + + + + + + + + + + + + + + + 67 

Special Senses System 

Harderian gland 1 

Adenoma 1 

Urinary System 

Kidney + + + + + + + + + + + + + + + + + 67 

Urethra + + 4 

Urinary bladder + + + + + + + + + + + + + + + + + 63 

Transitional epithelium, papilloma 1 

Systemic Lesions 

Multiple organs + + + + + + + + + + + + + + + + + 67 

Lymphoma malignant 2 
Lesions in Male Mice 233 

TABLE C2 

Individual Animal Tumor Pathology of Male Mice in the 2-Year Inhalation Study of Nickel Oxide: 2.5 mg/m 3 

Number of Days on Study 

1233444445555555666666666 

5456688881333458002446666 

5568323396999020359890055 

Carcass ID Number 

3333333433333333333333333 

5737369042225574259378938 

1263194042380446161497089 

Alimentar~ System 

Esophagus 

Gallbladder 

Intestine large, colon 

Intestine large, rectum 

Intestine large, cecum 

Intestine small, duodenum 

Adenoma 

Intestine small, jejunum 

Intestine small, ileum 

Liver 

Hepatocellular carcinoma 

Hepatocellular carcinoma, multiple 

Hepatocellular adenoma 

Hepatocellular adenoma, multiple 

Pancreas 

Salivary glands 

Stomach, forestomach 

Stomach, glandular 

Tooth 

Odontoma 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

A + +M+ + +A +A + + +A + + +A + ÷ + + + + + 

+A +A + + + + +A + + +A + + + + + + + + + + + 

MA +A + + + + +A + + +A + + + + + + +M+ + + 

+A +A + + + + +A + + +A + + +M+ + + + + + + 

A A +A + + +A +A + + +A + + +A + + + + + + + 

A A +A + + +A +A + + +A + + +A + + + + + + + 

A A +A + + +A +A + + +A + + +A + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

XXX XX 

X 

X X X X 

X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+A + + + + + + + + + + + + + + + + + + + + + + + 

+A + + + + + + + + + + + + + + + + + + + + + + + 

Cardiovascular System 

Hea~ + + + + + + + + + + + + + + + + + + + + + + + + + 

Endocr~e System 

Ad~nalco~ex + + + + + + + + + + + + + + + + + + + + + + + + + 

Capsule, adenoma 

Adrenal medulla 

Islets, pancreatic 

Adenoma 

Parathyroid gland 

Pituitary gland 

Thyroid gland 

Follicular cell, adenoma 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

MM+M+ + + + +M+ +MMM+ + + + + +M+ + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

General Body System 

Tissue NOS 

Lipoma 

Genital System 

Epididymis 

Penis 

Preputial gland 

Prostate 

Seminal vesicle 

Testes 

Interstitial cell, adenoma 

+ +M+ + + + + + + + + + + + + +M+ + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 
234 Nickel Oxide, NTP TR 451 

TABLE C2 

Individual Animal Tumor Pathology of Male Mice in the 2-Year Inhalation Study of Nickel Oxide: 2.5 mg/m 3 (continued) 

Number of Days on Study 

6666666777777777777777777 

7777899001133333333333333 

6679446492807777777777777 

Carcass ID Number 

3333333333333333333333333 

5658432688942235556666789 

8791797820824572370356082 

Alimentary System 

Esophagus 

Gallbladder 

Intestine large, colon 

Intestine large, rectum 

Intestine large, cecum 

Intestine small, duodenum 

Adenoma 

Intestine small, jejunum 

Intestine small, ileum 

Liver 

Hepatocellular carcinoma 

Hepatocellular carcinoma, multiple 

Hepatocellular adenoma 

Hepatocellular adenoma, multiple 

Pancreas 

Salivary glands 

Stomach, forestomach 

Stomach, glandular 

Tooth 

Odontoma 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + +A + +M+ +M+ + + + + + + + + + + + + 

+ + + + + + + +MA + + + + + + + + + + + + + + + 

+ + + +M+ + +MA + + + + +M+ + + +I M+ + + 

+ + + + + + + + + A + + + + + + + + + + + + + + + 

+ + + + +A + +AA + ++ + + + + + + + + + + + + 

+ + + + + A + + A A + + + + + + + + + + + + + + + 

+ + + + +A + +AA + + + + + + + +M+ + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

X X 

X X X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ 

Cardiovascular System 

Hea~ + + + + + + + + + + ÷ + + + + + + + + + + + + + + 

Endocr~e System 

Adrenalcoaex + + + + + + + + + + + + + + + + + + + + + + + + + 

Capsule, adenoma 

Adrenal medulla 

Islets, pancreatic 

Adennma 

Parathyroid gland 

Pituitary gland 

Thyroid gland 

Follicular cell, adenoma 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + ~ + + + + + + + + + + + + + + + + + + + 

M+ + + + + + + +M+M+ + + +M+ + + + + + + + 

+ + + + + + + +M+ + + + + + + + + + + + + + + + 

+ + + ~ + + + + + + + + + + + + + + + + + + + + + 

X X 

General Body System 

Tissue NOS 

Lipoma 

+ 

Genital System 

Epididymis 

Penis 

Preputial gland 

Prostate 

Seminal vesicle 

Testes 

Interstitial cell, adenoma 

+ + ++++ ++++ + + + + ++ + +M+ + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 
Lesions in Male Mice 235 

TABLE C2 

Individual Animal Tumor Pathology of Male Mice in the 2-Year Inhalation Study of Nickel Oxide: 2.5 mg/m 3 (continued) 

Number of Days on Study 

7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 

3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 

7 8 8 8 8 8 8 8 8 8 8 9 9 9 9 9 

Carcass ID Number 

3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 

9 2 3 3 4 4 6 7 7 8 9 2 3 4 4 5 

5 9 0 3 0 5 2 5 7 6 6 6 5 3 8 5 

Alimentary System 

Esophagus + + + + + + .+ + + + + + + + + + 66 

Gallbladder + + + + + + + + + + + + + + + + 57 

Intestine large, colon + + + + + + + + + + + + + + + + 60 

Intestine large, rectum I + M + + + + + + + + + + + + + 52 

Intestine large, cecum + + + + + + + + + + + + + + + + 60 

Intestine small, duodenum + + + + + + + + + + + + + + + + 56 

Adenoma X 1 

Intestine small, jejunum + + + + + + + + + + + + + + + + 56 

Intestine small, ileum + + + + + + + + + + + + + + + + 55 

Liver + + + + + + + + + + + + + + + + 66 

Hepatocellular carcinon~a X X 8 

Hepatocellular carcinoma, multiple 3 

Hepatocellular adenoma X X X X 11 

Hepatocellular adenoma, multiple X 2 

Pancreas + + + + + + + + + + + + + + + + 66 

Salivary glands + + + + + + + + + + + + + + + + 66 

Stomach, forestomach + + + + + + + + + + + + + + + + 65 

Stomach, glandular + + + + + + + + + + + + + + + + 65 

Tooth + + + 4 

Odontoma X X 2 

Cardiovascular System 

Heart + + + + + + + + + + + + + + + + 66 

Endocrine S~,stem 

Adrenal cortex + + + + + M + + + + + + + + + + 65 

Capsule, adenoma X 1 

Adrenal medulla + + + + + M + + + + + + + + + + 65 

Islets, pancreatic + + + + + + + + + + + + + + + + 66 

Adenoma 1 

Parathyroid gland + + + + + + + + + + + M + + + + 53 

Pituitary gland M + + + + + + + + + + + + + + M 63 

Thyroid gland + + + + + + + + + + + + + + + + 66 

Follicular cell, adenoma 2 

General Body System 

Tissue NOS + 3 

Lipoma X 1 

Genital System 

Epididymis + + + + + + + + + + + + + + + + 66 

Penis 7 

Preputial gland + + + + + + + + + + + + + + + + 66 

Prostate + + + + + + + + + + + + + + + + 63 

Seminal vesicle + + + + + + + + + + + + + + + + 66 

Testes + + + + + + + + + + + + + + + + 66 

Interstitial cell, adenoma X 2 
236 Nickel Oxide, NTP TR 451 

TABLE C2 

Individual Animal Tumor Pathology of Male Mice in the 2-Year Inhalation Study of Nickel Oxide: 2.5 mg/m 3 (continued) 

Number of Days on Study 

1233444445555555666666666 

5456688881333458002446666 

5568323396999020359890055 

Carcass ID Number 

3333333433333333333333333 

5737369042225574259378938 

1263194042380446161497089 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + ++++ ++++ ++ ++ 

I M++++ +++++++ + ++++ ++ ++ + + + 

++ ++++++ ++ ++ + ++++ ++ + + +M++ 

+M+M++I + +M+ + + +M+M++ + +++ ++ 

MMMMMMMM + + + MMMMMMM + MMMM + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

Hematopoietic System 

Bone marrow 

Lymph node 

Lymph node, bronchial 

Lymph node, mandibular 

Lymph node, mesenteric 

Lymph node, mediastinal 

Hemangiosarcoma, metastatic 

Spleen 

Hemangiosarcoma 

~ymus M + + + + + + + + + + + + I M + + + + + M + + I + 

Integumentary System 

Ma~arygland + + + + + + + + + + + + + + + + + + + + + + + + 

Skin + +++ ++ ++ ++ + 

Musculoskeletal System 

Bone + + + + + + + + + + + + + + + + + + + + + + + + + 

Nervous System 

Brain + + + + + + + + + + + + + + + + + + + + + + + + + 

Respiratory System 

Larynx 

Lung 

Alveolar/bronchiolar adenoma 

Alveolar/bronchiolar carcinoma 

Hepatocellular carcinoma, metastatic 

Nose 

Trachea 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

X X 

÷ + + ÷ + ÷ + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

Special Senses System 

Harderian gland 

Adenoma 

+ 

X 

Urinary System 

Kidney 

Ureter 

Urethra 

Urinary bladder 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ 

+ + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

Systemic Lesions 

Multiple organs 

Lymphoma malignant 
Lesions in Male Mice 237 

TABLE C2 

Individual Animal Tumor Pathology of Male Mice in the 2-Year Inhalation Study of Nickel Oxide: 2.5 mg/m 3 (continued) 

Number of Days on Study 

6666666777777777777777777 

7777899001133333333333333 

6679446492807777777777777 

Carcass ID Number 

3333333333333333333333333 

5658432688942235556666789 

8791797820824572370356082 

Hematopoietic System 

Bone marrow 

Lymph node 

Lymph node, bronchial 

Lymph node, mandibular 

Lymph node, mesenteric 

Lymph node, mediastinal 

Hemangiosarcoma, metastatic 

Spleen 

Hemangiosarcoma 

Thymus 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + 

+ + + +++ +M++ + + + + + + + + +++ + + + + 

+ + + + + +M+ + + + + + + + +M+ + + + + + + + 

+ + + +++M+M+ + + + + + + + ++ + + + + + + 

+MMMM+M+MMM+MMI + +M+ +MM+ +M 

X 

+ + + + + + ++ + + + +++ + + + + ++ + ++ + + 

X 

+ + + + +M+ + +MM+ + + + + + + + + + + +M+ 

Integumentary System 

Ma~a~gla~ + + + + + + + + + + + + + + + + + + M + + + M + + 

Skin + + + + + + + + + + + + 

Musculoskeletal System 

Bone + + + + + + + + + + + + + + + + + + + + + + + + + 

Nervous System 

Brain + + + + + + + + + + + + + + + + + + + + + + + + + 

Respiratory System 

Larynx 

Lung 

Alveolar/bronchiolar adenoma 

Alveolar/bronchiolar carcinoma 

Hepatocellular carcinoma, metastatic 

Nose 

Trachea 

+ + + + + + + +M+ + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X X X X XX 

X X X 

X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

Special Senses System 

Harderian gland 

Adenoma 

+ 

X 

Urinary System 

Kidney 

Ureter 

Urethra 

Urinary bladder 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ 

++ + 

++++ +++ +++++ + + + +M+++ + ++ + + 

Systemic Lesions 

Multiple organs 

Lymphoma malignant X 
238 Nickel Oxide, NTP TR 451 

TABLE C2 

Individual Animal Tumor Pathology of Male Mice in the 2-Year Inhalation Study of Nickel Oxide: 2.5 mg/m 3 (continued) 

Number of Days on Study 

7777777777777777 

3333333333333333 

7888888888899999 

Carcass ID Number 

3333333333333333 

9233446778923445 

5903052576665385 

Total 

Tissues/ 

Tumors 

Hematopoietic System 

Bone marrow + + + + + + + + + + + + + + + + 66 

Lymph node + 20 

Lymph node, bronchial + + + + + + + + + + I + + + + M 61 

Lymph node, mandibular + + + + + + + + + + + + + + + + 63 

Lymph node, mesenteric + + + + + + M + + + + M + + + + 56 

Lymph node, mediastinal I + M + M M M + M + M + I M M M 21 

Hemangiosarcoma, metastatic 1 

Spleen + + + + + + + + + + + + + + + + 66 

Hemangiosarcoma X 2 

Thymus + I + M + M + + + M + M + + + + 52 

Integumentary System 

Mammary gland + + + + + + + + + + + + + + + + 63 

Skin + 24 

Musculoskeletal System 

Bone + + + + + + + + + + + + + + + + 66 

Nervous System 

Brain + + + + + + + + + + + + + + + + 66 

Respiratory System 

Larynx + + I + + + + + + + + + + + + + . 64 

Lung + + + + + + + + + + + + + + + + 66 

Alveolar/bronchiolar adenoma 6 

Alveolar/bronchiolar carcinoma X X X X X 9 

Hepatocellular carcinoma, metastatic 3 

Nose + + + + + + + + + + + + + + + + 66 

Trachea + + + + + + + + + + + + + + + + 66 

Special Senses System 

Harderian gland 2 

Adenoma 2 

Urinary System 

Kidney + + + + + + + + + + + + + + + + 66 

Ureter 2 

Urethra 5 

Urinary bladder + + + + + + + + + + + + + + + + 65 

Systemic Lesions 

Multiple organs + + + + + + + + + + + + + + + + 66 

Lymphoma malignant X 2 
Lesions in Male Mice 239 

TABLE C2 

Individual Animal Tumor Pathology of Male Mice in the 2-Year Inhalation Study of Nickel Oxide: 5 mg/m 3 

Number of Days on Study 

0112223444444555555555566 

2392471223589023457788901 

1744117281999178391400712 

Carcass ID Number 

4545455555555545455555555 

9084925223211490844303426 

9166567824076008541602990 

Alimentary System 

Esophagus 

Gallbladder 

Intestine large, colon 

Intestine large, rectum 

Intestine large, cecum 

Intestine small, duodenum 

Intestine small, jejunum 

Intestine small, ileum 

Liver 

Alveolar/bronchiolar carcinoma, 

metastatic, lung 

Hemangiosarcoma 

Hepatocellular carcinoma 

Hepatocellular carcinoma, multiple 

Hepatocellular adenoma 

Hepatocholangiocarcinoma 

Histiocytic sarcoma 

Pancreas 

Salivary glands 

Stomach, forestomach 

Squamous cell papilloma 

Stomach, glandular 

Tooth 

Odontoma 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

M+M+ + + +A + +A + +A + + +A + + + + + + + 

+ +A + +A +A + +A + +A + + + + + + + + + + + 

M+A + +A +A + + +M+A + + + +M+ + + + + + 

+ +A + +A +A + +A +MA + + + +M+ + +M+ + 

A +A + +A +A + +A +AA + + + + + + + + + + + 

A +A + +A +A + +A +AA + + + + + + + + + + + 

A +A + +A +A + +A +A A + + +M+ + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X X X XX 

X 

XX X 

X 

X 

+ + + + + + +M + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + +A + + + + + + + + + + + + + + + + + 

+ + + + + + + A + + + + + + + + + + + + + + + + + 

Cardiovascular System 

Heart 

Alveolar/bronchiolar carcinoma, 

metastatic, lung 

Hepatocholangiocarcinoma, metastatic, liver 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

Endocrine System 

Adrenal cortex 

Adenoma 

Adrenal medulla 

Islets, pancreatic 

Parathyroid gland 

Pituitary gland 

Thyroid gland 

Follicular cell, adenoma 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + +M+ + + + + + + + + + + + + + + + + + 

+ + + + + + +M+ + + + + + + + + + + + + + + + + 

MMMMMMM+ + + + + + + +M+ + + + + + + +M 

+ M + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

General Body System 

Tissue NOS 

Alveolar/bronchiolar carciooma, 

metastatic, lung 

Hepatocholangiocarcinoma, metastatic, liver 

Sarcoma 

+ 

X 

+ + 
240 Nickel Oxide, NTP TR 451 

TABLE C2 

Individual Animal Tumor Pathology of Male Mice in the 2-Year Inhalation Study of Nickel Oxide: 5 mg/m 3 (continued) 

Number of Days on Study 

6666666666666777777777777 

1134557779999001112233333 

5651990067888463466667777 

Carcass ID Number 

5555555555455555555544455 

0051243442805211552389901 

7991771355223423843741860 

Alimentary System 

Esophagus 

Gallbladder 

Intestine large, colon 

Intestine large, rectum 

Intestine large, cecum 

Intestine small, duodenum 

Intestine small, jejunum 

Intestine small, ileum 

Liver 

Alveolar/bronchiolar carcinoma, 

metastatic, lung 

Hemangiosarcoma 

Hep.atocellular carcinoma 

Hepatocellular carcinoma, multiple 

Hepatocellular ad~noma 

Hepatocholangiocarcinoma 

Histiocytic sarcoma 

Pancreas 

Salivary glands 

Stomach, forestomach 

Squamous cell papilloma 

Stomach, glandular 

Tooth 

Odontoma 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + +AAA + + + + + +MM+ + + + + + + + + + + 

+ + + +AA + + + + + + + + + + + + + + + + + + + 

+ + + +AA + + +M+ + + + + + + + + +M+ + +M 

+ + + +A + + + + + + + + + + + + + + + + + + + + 

+ + +AAA + + + + + + + +M+ + + + + + + + + + 

+ + +AAA + + + + + + + + + + + + + + + + + + + 

+ + +A AA + + + + + + + + + +M+ + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

X 

X X 

X X X X 

X X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + +A + + + + + + + + + + + + + + + + + + + 

+++ + +A ++ + + + + + + + + + + + + +++ + + 

Cardiovascular System 

Heart 

Alveolar/bronchiolar carcinoma, 

metastatic, lung = 

Hepatocholangiocarcinoma, metastatic, liver 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

Endocrine System 

Adrenal cortex 

Adenoma 

Adrenal medulla 

Islets, pancreatic 

Parathyroid gland 

Pituitary gland 

Thyroid gland 

Follicular cell, adenoma 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + +M+ +M+ + + + + + + + + + + + + 

+ +M+ + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

General Body System 

Tissue NOS 

Alveolar/bronchiolar carcinoma, 

metastatic, lung 

Hepatocholangiocarcinoma, metastatic, liver 

Sarcoma 

+ 

X 
Lesions in Male Mice 241 

TABLE C2 

Individual Animal Tumor Pathology of Male Mice in the 2-Year Inhalation Study of Nickel Oxide: 5 mg/m 3 (continued) 

Number of Days on Study 

7777777777777777777 • 

3333333333333333333 

7777788889999999999 

Carcass ID Number 

5555544554444455555 

1345588338889900455 

9320539091784635826 

Total 

Tissues/ 

Tumors 

Alimentary System 

Esophagus 

Gallbladder 

Intestine large, colon 

Intestine large, rectum 

Intestine large, cecum 

Intestine small, duodenum 

Intestine small, jejunum 

Intestine small, ileum 

Liver 

Alveolar/bronchiolar carcinoma, 

metastatic, lung 

Hemangiosarcoma 

Hepatocellular carcinoma 

Hepatocellular carcinoma, multiple 

Hepatocellular adenoma 

Hepatocholangiocarcinoma 

Histiocytic sarcoma 

Pancreas 

Saliva~ glands 

Stomach, forestomach 

Squamous cell papilloma 

Stomach, glandular 

Tooth 

Odontoma 

+ + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + 

+ + +M+MM+ + + +MMM+MM+M 

+ + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + ~ + + + + 

+ + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + 

X X X 

XXX X 

X 

+ + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + 

X 

+ + + + + + + + + + + + + + + + + + + 

+ 

X 

69 

58 

62 

48 

60 

58 

59 

57 

69 

1 

2 

13 

2 

9 

1 

1 

68 

69 

67 

1 

67 

1 

1 

Cardiovascular System 

Heart 

Alveolar/bronchiolar carcinoma, 

metastatic, lung 

Hepatocholangiocarcinoma, metastatic, liver 

+ + + + + + + + + + + + + + + + + + + 69 

| 

1 

Endocrine System 

Adrenal cortex 

Adenoma 

Adrenal medulla 

Islets, pancreatic 

Parathyroid gland 

Pituitary gland 

Thyroid gland 

Follicular cell, adenoma 

+ + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + 

+ + +M+ + + + + + + + + + + + + + + 

+ + I + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + 

XX 

69 

1 

68 

68 

57 

66 

69 

2 

General Body System 

Tissue NOS 

Alveolar/bronchiolar carcinoma, 

metastatic, lung 

Hepatocholangiocarcinoma, metastatic, liver 

Sarcoma 
242 Nickel Oxide, NTP TR 451 

TABLE C2 

Individual Animal Tumor Pathology of Male Mice in the 2-Year Inhalation Study of Nickel Oxide: 5 mg/m 3 (continue0) 

Number of Days on Study 

0112223444444555555555566 

2392471223589023457788901 

1744117281999178391400712 

Carcass ID Number 

4545455555555545455555555 

9084925223211490844303426 

9166567824076008541602990 

Genital System 

Epididymis 

Penis 

Preputial gland 

Prostate 

Seminal vesicle 

Testes 

+ + +M + + + + + + + + + + + + + + + + + + + + + 

+ + ++ ++ 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + +M+MM+ + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

Hematopoietic System 

Bone marrow 

Lymph node 

Axillary, alveolar/bronchiolar 

carcinoma, metastatic, lung 

Lymph node, bronchial 

Hepatocholangiocarcinoma, metastatic, liver 

Lymph node, mandibular 

Lymph node, mesenteric 

Hepatocholangiocarcinoma, metastatic, liver 

Lymph node, mediastinal 

Spleen 

Hemangioma 

Hemangiosarcoma 

Histiocytic sarcoma 

Thymus 

Alveolar/bronchiolar carcinoma, 

metastatic, lung 

Hepatocholangiocarcinoma, metastatic, liver 

Histiocytic sarcoma 

+ + + + + + + A + + + + + + + + + + + + + + + + + 

++ ++ + ++ + 

M+M+M+MA M+ + + + + + + + + + + + + + + ! 

X 

+ +M+ + + +A MM+ + + +M+ + + + + + + + +M 

+ + +M+ + +M+ +M+ +M+ + + + + + + + + + + 

X 

M+MMMMM+ +MM+MM+M+M+ +M+MMM 

++ + + + ++ + + + + + + + + + + + + + + + + + + 

X 

X 

++ +M+ + +++ + + + +M+ + +MM+ + +I + + 

X 

X 

Integumentary System 

Ma~arygla~ + + + + + + + + + + + + + + + + + + + + + + + + + 

Skin + ++ + + +++++ 

Musculoskeletal System 

Bone + + + + + + + + + + + + + + + + + + + + + + + + I 

Nervous System 

B~in + + + + + + + + + + + + + + + + + + + + + + + + + 

Respiratory System 

Larynx 

Lung 

Alveolar/bronchiolar adenoma 

Alveolar/bronchiolar carcinoma 

Alveolar/bronchiolar carcinoma, multiple 

Hepatocellular carcinoma, metastatic 

Hepatocholangiocarcinoma, metastatic, liver 

Histiocytic sarcoma 

Nose 

Trachea 

+ + + + + + + + + + + + + + + + + + + + + + + ÷ + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

X 

X X 

X 

X 

+ + + + + ++A ÷ +A + + + +++ + + + + + + +.+ 

+ + + + + + + + + + + + + + + + + + + + + + + + • 
Lesions in Male Mice 243 

TABLE C2 

Individual Animal Tumor Pathology of Male Mice in the 2-Year Inhalation Study of Nickel Oxide: 5 mg/m 3 (continued) 

Number of Days on Study 

6666666666666777777777777 

1134557779999001112233333 

5651990067888463466667777 

Carcass ID Number 

5555555555455555555544455 

0051243442805211552389901 

7991771355223422843741860 

Genital System 

Epididymis 

Penis 

Preputial gland 

Prostate 

Seminal vesicle 

Testes 

+ + + + + +.+ + + + + + + + + + + + + + + + + + + 

+ + + +++ + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

Hematopoietic System 

Bone marrow 

Lymph node 

Axillary, alveolar/bronchiolar 

carcinoma, metastatic, lung 

Lymph node, bronchial 

Hepatocholangiocarcinoma, metastatic, liver 

Lymph node, mandibular 

Lymph node, mesenteric 

Hepatocholangiocarcinoma, metastatic, liver 

Lymph node, mediastinal 

Spleen 

Hemangioma 

Hemangiosarcoma 

Histiocytic sarcoma 

Thymus 

Alveolar/bronchiolar carcinoma, 

metastatic, lung 

Hepatocholangiocarcinoma, metastatic, liver 

Histiocytic sarcoma 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

++ + +++ + 

X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + +MM+ + + + + + + + + 

+ + + +M+ + + + + + + + + + + + + + + + + + + + 

+ + + +M+M+ +M+ +M+MI MM+M+MI MM 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

+ +M+ + + + +MM+ + + + + + + + +M+ + + + + 

X 

Integumentary System 

Mammarygland + + + + + + + + + + + + + + + + + + + + +-+ + + + 

Skin + + + + + + + + + + + + 

Musculoskeletal System 

Bone + + + + + + + + + + + + + + + + + + + + + + + + + 

Nervous System 

B~in + + + + + + + + + + + + + + + + + + + + + + + + + 

Respiratory System 

Larynx 

Lung 

Alveolar/bronchiolar adenoma 

Alveolar/bronchiolar carcinoma 

Alveolar/bronchiolar carcinoma, multiple 

Hepatocellular carcinoma, metastatic 

Hepatocholangiocarcinoma, metastatic, liver 

Histiocytic sarcoma 

Nose 

Trachea 

+ + + + + + + + + + + + + + + + + + + + + + + +M 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X X X X X X 

X X 

X 

X X 
244 Nickel Oxide, NTP TR 451 

TABLE C2 

Individual Animal Tumor Pathology of Male Mice in the 2-Year Inhalation Study of Nickel Oxide: 5 mg/m 3 (continued) 

Number of Days on Study 

7777777777777777777 

3333333333333333333 

7777788889999999999 

Carcass ID Number 

5555544554444455555 

1345588338889900455 

9320539091784635826 

Total 

Tissues/ 

Tumors 

Genial System 

Epid~ymis + + + + + + + + + + + + + + + + + + + 68 

~nis 13 

P~putialgland + + + + + + + + + + + + + + + + + + + 69 

Prosta~ + + + + + + + + + + + + + + I + + + + 65 

Semi~lvesicle + + + + + + + + + + + + + + + + + + + 69 

Tests .+ + + + + + + + + + + + + + + + + + + 69 

Hematopoietic System 

Bone marrow 

Lymph node 

Axillary, alveolar/bronchiolar 

carcinoma, metastatic, lung 

Lymph node, bronchial 

Hepatocholangiocarcinoma, metastatic, liver 

Lymph node, mandibular 

Lymph node, mesenteric 

Hepatocholangiocarcinoma, metastatic, liver 

Lymph node, mediastinal 

Spleen 

Hemangioma 

Hemangiosarcoma 

Histiocytic sarcoma 

Thymus 

Alveolar/bronchiolar carcinoma, 

metastatic, lung 

Hepatocholangiocarcinoma, metastatic, liver 

Histiocytic sarcoma 

+ + + + + + + + + + + + + + + + + + + 

+ 

+ + + + + + + + + + + + + + + + + + + 

+ +M + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + M + + + + 

+MI I M+MMMI MMMMMM+I + 

+ + + + + + + + + + + + + + + + + + + 

+I M+ + + + + + + + + + + + + + + + 

68 

16 

1 

62 

1 

60 

63 

1 

25 

69 

1 

1 

1 

58 

Integumentary ~ystem 

Mammary gland + + + + + + + + + + + + + + + + + + + 69 

Skin + + + + + 27 

Musculoskeletal System 

Bone + + + + + + + + + + + + + + + + + + + 68 

Nervous System 

Brain + + + + + + + + + + + + + + + + + + + 69 

Respiratory System 

Larynx M + + + + + + + + + + + + + + I + + + 66 

Lung + + + + + + + + + + + + + + + + + + + 69 

Alveolar/bronchiolar adenoma X X X X 11 

Alveolar/bronchiolar carcinoma X X 5 

Alveolar/bronchiolar carcinoma, multiple 1 

Hepatocellular carcinoma, metastatic 4 

Hepatocholangiocarcinoma, metastatic, liver 1 

Histiocytic sarcoma 1 

Nose + + + + + + + + + + + + + + + + + + + 67 

Trachea + + + M + + + + + + + + + + + + + + + 68 
Lesions in Male Mice 245 

TABLE C2 

Individual Animal Tumor Pathology of Male Mice in the 2-Year Inhalation Study of Nickel Oxide: 5 mg/m 3 (continued) 

Number of Days on Study 

0112223444444555555555566 

2392471223589023457788901 

1744117281999178391400712 

Carcass ID Number 

4545455555555545455555555 

9084925223211490844303426 

9166567824076008541602990 

Special Senses System 

Harderian gland 

Adenoma 

Urinary System 

Kidney 

Ureter 

Urethra 

Urinary bladder 

+ + + + + + + A + + + + + + + + + + + + + + + + + 

+ + + 

+ + + ++ 

+ +A + + + +A + + + + + + + + + + + + + + + + + 

Systemic Lesions 

Multiple organs 

Histiocytic sarcoma 

Lympboma malignant 

X 

X 
246 Nickel Oxide, NTP TR 451 

TABLE C2 

Individual Animal Tumor Pathology of Male Mice in the 2-Year Inhalation Study of Nickel Oxide: 5 mg/m 3 (continued) 

Number of Days on Study 

6666666666666777777777777 

1134557779999001112233333 

5651990067888463466667777 

Carcass ID Number 

5555555555455555555544455 

0051243442805211552389901 

7991771355223423843741860 

Special Senses System 

Harderian gland + 

Adenoma X 

Urinary System 

Kidney 

Ureter 

Urethra 

Urinary bladder 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ 

++ + + 

+ + + + + A + + + + + + + + + + + + + + + + + + + 

Systemic Lesions 

Multiple organs 

Histiocytic sarcoma 

Lymphoma malignant X X X 
Lesions in Male Mice 247 

TABLE C2 

Individual Animal Tumor Pathology of Male Mice in the 2-Year Inhalation Study of Nickel Oxide: 5 mg/m 3 (continued) 

Number of Days on Study 

7777777777777777777 

3333333333333333333 

7777788889999999999 

Carcass ID Number 

5555544554444455555 

134558833888990 Q 455 

9320539091784635826 

Total 

Tissues/ 

Tumors 

Special Senses System 

Harderian gland + + 3 

Adenoma X 2 

Urinary System 

Kidney + + + + + + + + + + + + + + + + + + + 68 

Ureter 4 

Urethra + + + 12 

Urinary bladder + + + + + + + + + + + + + + + + + + + 66 

Systemic Lesions 

Multiple organs + + + + + + + + + + + + + + + + + + + 69 

Histiocytic sarcoma 1 

Lymphoma malignant X 5 
248 Nickel Oxide, NTP TR 451 

TABLE C3 

Statistical Analysis of Primary Neoplasms in Male Mice in the 2-Year Inhalation Study of Nickel Oxide 

0 mg/m ~ 1.25 mg/m ~ 2.5 mg/m ~ 5 mg/m 3 

Adrenal Cortex: Adenoma 

Overall ratea 4/57 (7%) 

Adjusted raate b 21.1% 

Terminal rate c 4/19 (21%) 

First incidence (days) 737 (T) 

Life table test d P =0.122N 

Logistic regression test d P=0.113N 

Cochran-Armita~e test d P=0.137N 

Fisher exact test ~ 

Liver: Hepatocellular Adenoma 

Overall rate 8/57 (14%) 

Adjusted rate 34.9% 

Terminal rate 5/19 (26%) 

First incidence (days) 603 

Life table test P=0.432 

Logidtic regression test P=0.426 

Cochran-Armitage test P=0.404 

Fisher exact test 

Liver: Hepatocellular Carcinoma 

Overall rate 6/57 (11%) 

Adjusted rate 19.0% 

Terminal rate 1/19 (5%) 

First incidence (days) 392 

Life table test P=0.212 

Logistic regression test P=0.155 

Cochran-Armitage test P=0. t70 

Fisher exact test 

Liver: Hepatocellular Adenoma or Carcinoma 

Overall rate 12/57 (21%) 

Adjusted rate 41.4% 

Terminal rate 5/19 (26%) 

First incidence (days) 392 

Life table test P=0.308 

Logistic regression test P=0.237 

Cochran-Armitage test P=0.246 

Fisher exact test 

Lung: Aiveolar/bronchiolar Adenoma 

Overall rate 7/57 (12%) 

Adjusted rate 30.2 % 

Terminal rate 4/19 (21%) 

First incidence (days) 599 

Life table test P=0.206 

Logistic regression test P=0.196 

Cochran-Armitage test P = 0.179 

Fisher exact test 

0/67 (0%) 1/65 (2%) 1/69 (1%) 

0.0% 3.6% 3.7% 

0/23 (0%) 1/28 (4%) 0/23 (0%) 

_e 737 (T) 716 

P=0.039N P=0.079N P=0.120N 

P=0.039N P=0.079N P=0.101N 

P=0.042N P=0,144N P=0.129N 

5/67 (7%) 13/66 (20%) 9/69 (13%) 

18.0% 32.6% 26.4% 

3/23 (13%) 7/29 (24%) 4/23 (17%) 

626 482 431 

P=0.167N P=0.491 P=0.522N 

P=0.154N P=0.364 P=0.520N 

P=0.185N P=0.278 P=0.537N 

16/67 (24%) 11/66 (17%) 15/69 (22%) 

37.8% 24.9% 39.5% 

2/23 (9%) 3/29 (10%) 5/23 (22%) 

341 539 459 

P=0.073 P=0.379 P=0.095 

P=0.044 P=0.233 P=0.077 

P=0.043 P=0.236 P=0.073 

20/67 (30%) 23/66 (35%) 20/69 (29%) 

46.9% 50.3% 49.3% 

4/23 (17%) 10/29 (34%) 7/23 (30%) 

341 482 431 

P=0.247 P=0.240 P=0.246 

P=0.181 P=0.092 P=0.216 

P=0.182 P=0.067 P =0.209 

5/67 (7%) 6/66 (9%) 11/69 (16%) 

16.2% 18.3% 33.0% 

2/23 (9%) 4/29 (14%) 5/23 (22%) 

512 676 489 

P=0.259N P=0.221N P=0.409 

P =0.255N P=0.242N P=0.403 

P=0.274N P =0.388N P=0.374 
Lesions in Male Mice 249 

TABLE C3 

Statistical Analysis of Primary Neoplasms in Male Mice in the 2-Year Inhalation Study of Nickel Oxide (continued) 

0 mg/m 3 1.25 mg/m ~ 2.5 mg/m ~ 5 mg/m ~ 

Lung: Alveolar/bronchiolar Carcinoma 

Overall rate 4/57 (7 %) 

Adjusted rate 16.9% 

Terminal rate 2/19 (11%) 

First incidence (days) 559 

Life table test P=0.449N 

Logistic regression test P=0.444N 

Cochran-Armitage test P=0.485N 

Fisher exact test 

10/67 (15%) 9/66 (14%) 6/69 (9%) 

32.4% 27.3% 19.6% 

5/23 (22%) 7/29 (24%) 3/23 (13%) 

616 483 571 

P=0.160 P=0.321 P=0.520 

P=0.141 P=0.263 P=0.520 

P=0.135 P=0.186 P = 0.497 

Lung: Alveolar/bronchiolar Adenoma or Carcinoma 

Overall rate 9/57 (16%) 14/67 (21%) 15/66 (23%) 14/69 (20%) 

Adjusted rate 36.3% 41.4% 43.6% 39.7% 

Terminal rate 5/19 (26%) 6/23 (26%) 11/29 (38%) 6/23 (26%) 

First incidence (days) 559 512 483 489 

Life table test " P=0.404 P=0.355 P=0.467 P=0.381 

Logistic regression test P=0.393 P=0.322 P=0.380 P=0.364 

Cochran-Armitage test P=0.353 

Fisher exact test P=0.311 P=0.230 P=0.339 

All Organs: Hemangiosarcoma 

Overall rate 3/57 (5%) 

Adjusted rate 10.3 % 

Terminal rate 1/19 (5%) 

First incidence (days) 559 

Life table test P=0.545N 

Logistic regression test P=0.554N 

Cochran-Armitage test P=0.559N 

Fisher exact test 

All Organs: Hemangiosarcoma or Hemangioma 

Overall rate 3/57 (5 %) 

Adjusted rate 10.3 % 

Terminal rate 1/19 (5%) 

First incidence (days) 559 

Life table test P=0.453 

Logistic regression test P=0.435 

Cochran-Armitage test P=0.429 

Fisher exact test 

All Organs: Malignant Lymphoma 

Overall rate 2/57 (4%) 

Adjusted rate 6.5 % 

Terminal rate 0/19 (0%) 

First incidence (days) 590 

Life table test P=0.177 

Logistic regression test P=0.156 

Cochran-Armitage test P=0.156 

Fisher exact test 

2/67 (3%) 2/66 (3%) 3/69 (4%) 

5.7% 6.9% 8.4% 

0/23 (0%) 2/29 (7%) 0/23 (0%) 

604 737 (T) 271 

P=0.404N P=0.343N P=0.552N 

P=0.425N P=0.385N P=0.572N 

P=0.423N P=0.431N P=0.565N 

2/67 (3%) 2/66 (3%) 4/69 (6%) 

5.7% 6.9% 11.1% 

0/23 (0%) 2/29 (7%) 0/23 (0%) 

604 737 (T) 271 

P=0.404N P=0.343N P=0.634 

P=0.425N P=0.385N P=0.604 

P=0.423N P=0.431N P=0.606 

2/67 (3%) 2/66 (3%) 5/69 (7%) 

4.5% 6.9% 12.8% 

0/23 (0%) 2/29 (7%) 1/23 (4%) 

501 737 (T) 137 

P=0.626N P=0.558N P=0.346 

P=0.635N P=0.594N P=0.299 

P=0.627N P=0.633N P=0.306 
250 Nickel Oxide, NTP TR 451 

TABLE C3 

Statistical Analysis of Primary Neoplasms in Male Mice in the 2-Year Inhalation Study of Nickel Oxide (continued) 

0 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 5 mg/m 3 

All Organs: Benign Neoplasms 

Overall rate 19/57 (33 %) 

Adjusted rate 71.4% 

Terminal rate 12/19 (63%) 

First incidence (days) 599 

Life table test P=0.221 

Logistic regression test P=0.190 

Cochran-Armitage test P=0.169 

Fisher exact test 

17/67 (25%) 26/66 (39%) 26/69 (38%) 

50.0% 61.9% 67.1% 

8/23 (35%) 15/29 (52%) 12/23 (52%) 

480 482 431 

P=0.183N P=0.458N P=0.434 

P=0.176N P=0.495 P=0.416 

P=0.219N P=0.306 P=0.375 

All Organs: Malignant Neoplasms 

Overall rate 15/57 (26%) 28/67 (42%) 23/66 (35%) 30/69 (43%) 

Adjusted rate 43.3% 60.7% 54.0% 61.9% 

Terminal rate 4/19 (21%) 7/23 (30%) 12/29 (41%) 8/23 (35%) 

First incidence (days) 392 341 483 137 

Life table test P=0.136 P=0.111 P=0.471 P=0.080 

Logistic regression test P=0,070 P=0,039 P=0,267 P=0.035 

Cochran-Armitage test P=0.072 

Fisher exact test P=0.053 P=0,205 P=0.034 

All Organs: Benign or Malignant Neoplasms 

Overall rate 30/57 (53%) 37/67 (55%) 40/66 (61%) 44/69 (64%) 

Adjusted rate 84.1% 76.0 % 85.8 % 81.5 % 

Terminal rate 14/19 (74%) 12/23 (52%) 23/29 (79%) 14/23 (61%) 

First incidence (days) 392 341 482 137 

Life table test P=0.214 P=0.538 P=0.392N P=0.258 

Logistic regression test P=0.110 P=0.455 P=0.434 P=0.145 

Cochran-Armitage test P=0.099 

Fisher exact test P=0.457 P=0,239 P=0,140 

(T)Terminal sacrifice 

a Number of neoplasm-bearing animals/number of animals examined. 

b 

c 

d 

Denominator is number of animals examined microscopically for adrenal gland, liver, 

and lung; for other tissues, denominator is number of animals necropsied. 

Kaplan-Meier estimated neoplasm incidence at the end of the study after adjustment for intercurrent mortality 

Observed incidence at terminal kill 

Beneath the control incidence are the P values associated with the trend test. Beneath the dosed group incidence are the P values corresponding to 

pairwise comparisons between the controls and that dosed group. The life table test regards neoplasms in animals dying prior to terminal kill as being 

(directly or indirectly) the cause of death. The logistic regression test regards these lesions as nonfatal. The Cochran-Armitage and Fisher exact tests 

compare directly the overall incidence rates, For all tests, a negative trend or a lower incidence in a dose group is indicated by N. 

Not applicable; no neoplasms in animal group 
Lesions in Male Mice 251 

TABLE C4a 

Historical Incidence of Alveolar/bronchiolar Neoplasms in Untreated Male B6C3F1 Mice a 

Incidence in Controls 

Study Adenoma Carcinoma Adenoma or Carcinoma 

Historical Incidence at Lovelace Inhalation Toxicology Research Institute 

Nickel Oxide 7/57 4/57 9/57 

Nickel Subsulfide 6/61 7/61 13/61 

Nickel Sulfate Hexahydrate 5/61 9/61 13/61 

Talc 6/45 7/45 12/45 

Overall Historical Incidence in Inhalation Studies 

Total 141/952 (14.8%) 75/952 (7.9%) 

Standard deviation 7.0 % 5.7 % 

Range 6%-36% 0%-16% 

Overall Historical Incidence in Feed Studies 

Total 194/1,319 (14.7%) 64/1,319 (4.9%) 

Standard deviation 6.4% 3.9% 

Range 4%-28% 0%-14% 

205/952 (21.5%) 

8.0% 

10%-42% 

249/1,319 (18.9%) 

7.6% 

4%-32% 

a Data as of 17 June 1994 
252 Nickel Oxide, NTP TR 451 

TABLE C4b 

Historical Incidence of Hepatocellular Neopigsms in Untreated Male B6C3F~ Mice a 

Incidence in Controls 

Study Adenoma Carcinoma Adenoma or Carcinoma 

Historical Incidence at Lovelace Inhalation Toxicology Research Institute 

Nickel Oxide 8/57 6/57 12/57 

Nickel Subsulfide 13/61 11/61 24/61 

Nickel Sulfate Hexahydrate 18/61 11/61 27/61 

Talc 3/45 6/45 9/45 

Overall Historical Incidence in Inhalation Studies 

Total 201/952 (21.1%) 185/952 (19.4%) 360/952 (37.8%) 

Standard deviation 11.7% 5.8% 12.6% 

Range 4 % -46 % 9 % -29 % 11% -60 % 

Overall Historical Incidence in Feed Studies 

Total 344/1,316 (26.1%) 220/1,316 (16.7%) 509/1,316 (38.7%) 

Standard deviation 13.2 % 7.2 % 13.9 % 

Range 4 %-60 % 3 %-29 % 10 %-68 % 

a Data as of 17 June 1994 
Lesions in Male Mice 253 

TABLE C5 

Summary of the Incidence of Nonneoplastic Lesions in Male Mice in the 2-Year Inhalation Study of Nickel Oxide a 

0 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 5 mg/m 3 

Disposition Summary 

Animals initially in study 78 77 76 79 

7-Month interim evaluation 5 5 5 5 

15-Month interim evaluation 5 5 5 5 

Early Deaths 

Accidental deaths b 10 

Moribund 23 26 26 29 

Natural deaths 15 18 l l 17 

Survivors 

Terminal sacrifice 19 23 29 23 

Missexed 1 

Animals examined microscopically 67 77 76 79 

7-Month Interim Evaluation 

Genital System 

Preputial gland (3) (1) (2) 

Atrophy 1 (33%) 

Duct, concretion 1 (100%) 2 (100%) 

Duct, cctasia 3 (100%) 

Hematopoietic System 

Lymph node (1) 

Renal, pigmentation 1 (100%) 

Lymph node, bronchial (4) (3) (5) (4) 

Hyperplasia, lymphoid 1 (20%) 

Pigmentation 2 (67%) 5 (100%) 4 (100%) 

Respiratory System 

Lung (5) (5) (5) (5) 

Inflammation, chronic 2 (40%) 3 (60%) 3 (60%) 

Alveolus, pigmentation 5 (100%) 5 (100%) 5 (100%) 

Urinary System 

Kidney (5) (5) (5) 

Infiltration cellular, lymphocyte 1 (20%) l (20%) 

(5) 
254 Nickel Oxide, NTP TR 451 

TABLE C5 

Summary of the Incidence of Nonneoplastic Lesions in Male Mice in the 2-Year Inhalation Study of Nickel Oxide 

(continued) 

0 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 5 mg/m 3 

7-Month Interim Evaluation 

Systems Examined With No Lesions Observed 

Alimentary System 

Cardiovascular System 

Endocrine System 

General Body System 

Integumentary System 

Musculoskeletal System 

Nervous System 

Special Senses System 

15-Month Interim Evaluation 

Alimentary System 

Liver (5) 

Basophilic focus 

Eosinophilic focus 

Salivary glands (5) 

Infiltration cellular, lymphocyte 1 (20%) 

(5) 

1 (20%) 

(5) 

(5) 

(5) 

(5) 

I (20%) 

(5) 

Genital System 

Penis (1) 

Inflammation, suppurative 1 (100%) 

Preputial gland (5) 

Ectasia 4 (80%) 

Inflammation, suppurative 1 (20%) 

(5) 

5 (1oo%) 

1 (20%) 

(5) 

3 (60%) 

(5) 

2 (40%) 

Hematopoietic System 

Lymph node (1) 

Inguinal, hype~plasia, lymphoid 1 (100%) 

Renal, hyperplasia, lymphoid 1 (100%) 

Lymph node, bronchial (5) 

Hyperplasia, lymphoid 

Pigmentation 

Spleen (5) 

Hyperplasia, lymphoid 2 (40%) 

(5) 

4 (80%) 

(5) 

(5) 

2 (40%) 

5 (100%) 

(5) 

1 (20%) 

(5) 

4 (80%) 

5 (100%) 

(5) 

Respiratory System 

Lung 

Inflammation, chronic 

Bronchialization c 

Alveolar epithelium, hyperplasia, focal 

Alveolus, pigmentation 

Alveolus, proteinosis 

(5) 

1 (20%) 

1 (20%) 

(5) 

1 (20%) 

5 (100%) 

(5) 

2 (40%) 

5 (100%) 

1 (20%) 

(5) 

4 (80%) 

2 (40%) 

5 (100%) 

3 (60%) 
Lesions in Male Mice 255 

TABLE C5 

Summary of the Incidence of Nonneoplastic Lesions in Male Mice in the 2-Year Inhalation Study of Nickel Oxide 

(continued) 

0 mg/m a 1.25 mg/m 3 2.5 mg/m 3 5 mg/m 3 

15-Month Interim Evaluation (continued) 

Urinary System 

Urinary bladder (5) 

Calculus, microscopic observation only 1 (20%) 

(5) (4) (5) 

Systems Examined With No Lesions Observed 

Cardiovascular System 

Endocrine System 

General Body System 

Integumentary System 

Musculoskeletal System 

Nervous System 

Special Senses System 

2- Year Study 

Alimentary System 

Gallbladder 

Inflammation, chronic 

Necrosis 

Intestine large, cecum 

Hyperplasia, lymphoid 

Inflammation, chronic 

Intestine small, ileum 

Inflammation, suppurative 

Ulcer 

Liver 

Abscess 

Angiectasis 

Basophilic focus 

Clear cell focus 

Congestion 

Cyst 

Developmental malformation 

Eosinophilic focus 

Fatty change 

Hematopoietic cell proliferation 

Hepatodiaphragmatic nodule 

Hyperplasia, macrophage 

Infarct 

Inflammation, suppurative 

Mixed cell focus 

Thrombosis 

Bile duct, cyst 

Hepatocyte, cytomegaly 

Hepatocyte, cytoplasmic alteration 

Hepatocyte, hyperplasia 

Hepatocyte, necrosis 

(47) 

(49) 

(51) 

1 (2%) 

1 (2%) 

(57) 

1 (2%) 

1 (2%) 

1 (2%) 

1 (2%) 

1 (2%) 

5 (9%) 

(55) 

(56) 

(49) 

(67) 

1 (1%) 

2 (3%) 

1 (1%) 

1 (1%) 

6 (9%) 

1 (1%) 

3 (4%) 

1 (1%) 

2 (3%) 

(57) 

1 (2%) 

(60) 

I (2%) 

(55) 

(66) 

3 (5%) 

1 (2%) 

1 (2%) 

1 (2%) 

1 (2%) 

1 (2%) 

1 (2%) 

1 (2%) 

1 (2%) 

1 (2%) 

4 (6%) 

(58) 

1 (2%) 

(60) 

2 (3%) 

(57) 

(69) 

1 (1%) 

1 (1%) 

1 (1%) 

1 (1%) 

1 (1%) 

1 (1%) 

4 (6%) 

2 (3%) 

4 (6%) 
256 Nickel Oxide, NTP TR 451 

TABLE C5 

Summary of the Incidence of Nonneoplastic Lesions in Male Mice in the 2-Year Inhalation Study of Nickel Oxide 

(continued) 

0 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 5 mg/m 3 

2-Year Study (continued) 

Alimentary System (continued) 

Mesentery (1) (1) 

Hemorrhage 1 (100%) 

Thrombosis 1 (100%) 

Vein, inflammation, chronic 1 (100%) 

Pancreas (54) (65) (66) (68) 

Cyst 1 (1%) 

Inflammation, chronic 1 (2%) 

Inflammation, chronic active 1 (2 %) 

Stomach, forestomach (54) (63) (65) (67) 

Hyperkeratosis 1 (2%) 1 (2%) 1 (1%) 

Stomach, glandular (55) (63) (65) (67) 

Inflammation, chronic 1 (2%) 

Inflammation, suppurative 1 (2%) 2 (3%) 1 (1%) 

Tooth (2) (5) (4) (1) 

Dysplasia 2 (100%) 4 (80%) 1 (25%) 1 (100%) 

Peridontal tissue, inflammation, chronic 

active 1 (25%) 

Cardiovascular System 

Heart 

Inflammation, chronic 

Inflammation, suppurative 

Atrium, thrombosis 

Ventricle, thrombosis 

(57) (67) 

1 (1%) 

(66) 

1 (2%) 

(69) 

1 (1%) 

1 (1%) 

Endocrine System 

Adrenal cortex (57) (67) (65) 

Cyst 1 (2%) 

Hyperplasia 6 (11%) 5 (7%) 6 (9%) 

Bilateral, hyperplasia 1 (1%) 

Bilateral, spindle cell, hyperplasia 1 (2%) 

Spindle cell, hyperplasia 1 (2%) 2 (3%) 1 (2%) 

Islets, pancreatic (54) (64) (66) 

Hyperplasia 2 (4%) 2 (3%) 

Parathyroid gland (37) (48) (53) 

Cyst 1 (3%) 1 (2%) 

Hyperplasia, cystic 2 (4%) 

Pituitary gland (56) (62) (63) 

Pars distalis, cyst 1 (2%) 1 (2%) 

Pars distalis, hyperplasia 2 (4%) 1 (2%) 

Thyroid gland (55) (67) (66) 

Hyperplasia, cystic 13 (24%) 27 (40%) 25 (38%) 

Inflammation, chronic 1 (1%) 

Inflammation, suppurative 1 (2 %) 

(69) 

1 (1%) 

2 (3%) 

(68) 

(57) 

(66) 

1 (2%) 

(69) 

27 (39%) 
Lesions in Male Mice 257 

TABLE C5 

Summary of the Incidence of Nonneoplastic Lesions in Male Mice in the 2-Year Inhalation Study of Nickel Oxide 

(continued) 

0 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 5 mg/m 3 

2-Year Study (continued) 

General Body System 

Tissue NOS 

Abscess 

Hemorrhage 

Inflammation, suppurative 

Necrosis 

Necrosis, chronic 

(2) (3) (4) 

1 (50%) 

1 (33%) 

1 (33%) 

1 (25%) 

1 (25%) 

1 (25%) 

Genital System 

Epididymis (56) (67) (66) (68) 

Granuloma sperm 1 (1%) 1 (2%) 

Inflammatio n, chronic 2 (4%) 2 (3%) 

Inflammation, chronic active 1 (1%) 

Inflammation, suppurative 1 (1%) 

Penis (7) ( 11 ) (7) (13) 

Concretion 1 (14%) 5 (45%) 5 (71%) 5 (38%) 

Hemorrhage 1 (9%) 1 (14%) 

Inflammation 1 (9%) 1 (8%) 

Inflammation, chronic 1 (14%) 

Inflammation, suppurative 5 (71%) 1 (9%) 1 (14%) 6 (46%) 

Mineralization 1 (9%) 

Necrosis, chronic 1 (9%) 1 (14%) 

Preputial gland (57) (66) (66) (69) 

Atrophy 4 (6%) 2 (3%) 

Concretion 1 (2%) 

Ectasia 16 (28%) 17 (26%) 25 (38%) 20 (29%) 

Hemorrhage 1 (2%) 

Inflammation, chronic 2 (4%) 7 (11%) 5 (8%) 9 (13%) 

Inflammation, chronic active 9 (16%) 12 (18%) 7 (11%) 2 (3%) 

Inflammation, suppurative 14 (25%) 8 (12%) 13 (20%) 11 (16%) 

Bilateral, ectasia 23 (40%) 34 (52%) 37 (56%) 41 (59%) 

Bilateral, inflammation, chronic active 2 (3%) 1 (2%) 

Bilateral, inflammation, suppurative 1 (2%) 

Prostate (53) (61) (63) (65) 

Inflammation, chronic active 1 (2%) 

Inflammation, suppurative 1 (2%) 2 (3%) 1 (2%) 1 (2%) 

Epithelium, hyperplasia 1 (2%) 

Seminal vesicle (55) (66) (66) (69) 

Cyst 1 (1%) 

Dilatation 1 (2%) 8 (12%) 11 (17%) 10 (14%) 

Inflammation, chronic 1 (2%) 

Testes (57) (66) (66) (69) 

Atrophy 3 (5%) 1 (2%) 1 (1%) 

Congestion 1 (2%) 

Cyst 1 (2%) 

Inflammation, suppurative 1 (2%) 

Bilateral, atrophy 1 (1%) 

Germinal epithelium, degeneration 1 (1%) 
258 Nickel Oxide, NTP TR 451 

TABLE C5 

Summary of the Incidence of Nonneoplastic Lesions in Male Mice in the 2-Year Inhalation Study of Nickel Oxide 

(continued) 

0 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 5 mg/m 3 

2-Year Study (continued) 

Hematopoietic System 

Bone marrow (56) (66) (66) (68) 

Erythroid cell, hyperplasia 1 (1%) 

Myeloid cell, hyperplasia 5 (9%) 13 (20%) 15 (23%) 13 (19%) 

Myeloid cell, inflammation 1 (1%) 

Lymph node (22) (18) (20) (16) 

lliac, hyperplasia, histiocytic 1 (5%) 

Iliac, hyperplasia, lymphoid 8 (36%) 8 (44%) 11 (55%) 8 (50%) 

lliac, inflammation, suppurative 1 (6%) 

Iliac, pigmentation 4 (22%) 3 (15%) 2 (13%) 

Inguinal, hyperplasia 1 (5 %) 

Inguinal, hyperplasia, lymphoid 12 (55%) 9 (50%) 11 (55%) 9 (56%) 

Inguinal, pigmentation 1 (5 %) 2 (11%) 

Pancreatic, hyperplasia, lymphoid 1 (5%) 

Pancreatic, inflammation, granulomatous 1 (5%) 1 (5%) 

Renal, hyperplasia, histiocytic 1 (5%) 

Renal, hyperplasia, lymphoid 2 (9%) 2 (11%) I (5%) 

Renal, pigmentation 1 (6%) 

Lymph node, bronchial (45) (56) (61) (62) 

Atrophy 1 (2%) 

Congestion 1 (2%) 1 (2%) 1 (2%) 

Edema 1 (2%) 1 (2%) 

Hyperplasia, lymphoid 5 (11%) 18 (32%) 28 (46%) 33 (53%) 

Inflammation, chronic active 1 (2%) 

Inflammation, granulomatous 1 (2 %) 

Pigmentation 55 (98%) 61 (100%) 60 (97%) 

Lymph node, mandibular (47) (57) (63) (60) 

Hyperplasia, histiocytic 1 (2%) 

Hyperplasia, lymphoid 3 (6%) 3 (5%) 4 (6%) 2 (3%) 

Lymph node, mesenteric (45) (55) (56) (63) 

Congestion 4 (9%) 13 (24%) 12 (21%) 6 (10%) 

Hematopoietic cell proliferation 1 (2%) 3 (5%) 

Hyperplasia, lymphoid 3 (7%) 4 (7%) 5 (9%) 3 (5%) 

Hyperplasia, macrophage 1 (2%) 

Inflammation, suppurative 4 (9%) 1 (2%) 2 (4%) 1 (2%) 

Pigmentation 1 (2%) 

Lymph node, mediastinal (18) (19) (21) (25) 

Congestion 2 (8 %) 

Hyperplasia, lymphoid 1 (6%) 

Inflammation, chronic 1 (5 %) 

Pigmentation 3 (16%) 1 (5%) 1 (4%) 

Spleen (56) (67) (66) (69) 

Angiectasis 1 (1%) 

Hematopoietic cell proliferation 17 (30%) 14 (21%) 13 (20%) 17 (25%) 

Hyperplasia, lymphoid 2 (4%) 5 (7%) 6 (9%) 4 (6%) 

Thrombosis 2 (3%) 

Thymus (45) (53) (52) (58) 

Atrophy 1 (2%) 1 (2%) 1 (2%) 

Cyst 1 (2%) 

Inflammation, granulomatous 1 (2%) 

Pigmentation 1 (2%) 
Lesions in Male Mice 259 

TABLE C5 

Summary of the Incidence of Nonneoplastic Lesions in Male Mice in the 2-Year Inhalation Study of Nickel Oxide 

(continued) 

0 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 5 mg/m 3 

2-Year Study (continued) 

Integumentary System 

Skin 

Alopecia 

Cyst epithelial inclusion 

Inflammation. chronic 

Inflammation, chronic active 

Inflammation, suppurative 

Necrosis 

Prepuce, inflammation 

Prepuce, inflammation, chronic active 

Prepuce. inflammation, suppurative 

Prepuce, necrosis 

Subcutaneous tissue, edema 

Subcutaneous tissue, fibrosis 

Subcutaneous tissue, hemorrhage 

Subcutaneous tissue, inflammation, chronic 

active 

Subcutaneous tissue, inflammation, 

suppurative 

(16) (23) (24) (27) 

1 (6%) 1 (4%) 1 (4%) 

1 (4%) 

1 (4%) 

1 (6%) 2 (9%) 1 (4%) 

13 (81%) 11 (48%) 16 (67%) 13 (48%) 

2 (9%) I (4%) I (4%) 

1 (4%) 

1 (4%) 

5 (22%) 3 (13%) 4 (15%) 

1 (4%) 

2 (9%) 

1 (4%) 

1 (4%) 

1 (4%) 

1 (4%) 

1 (4%) 

Musculoskeletal System 

Bone 

Developmental malformation 

Fracture healed 

Hemorrhage 

Hyperostosis 

Vertebra, inflammation, suppurative 

Skeletal muscle 

Inflammation, suppurative 

(57) 

2 (4%) 

2 (4%) 

1 (2%) 

(1) 

1 (100%) 

(67) (66) (68) 

1 (2%) 

1 (1%) 1 (1%) 

1 (1%) 

4 (6%) 

Nervous System 

Brain 

Pons, demyelination 

(57) (67) (66) (69) 

2 (3%) 

Respiratory System 

Lung 

Congestion 

Fibrosis 

Hemorrhage 

Hyperplasia, macrophage 

Inflammation, chronic 

Thrombosis 

Bronchialization 

Alveolar epithelium, hyperplasia, focal 

Alveolus, pigmentation 

Alveolus, proteinosis 

Pleura, fibrosis 

(57) (67) (66) 

1 (2%) 

1 (1%) 2 (3%) 

1 (1%) 

21 (31%) 34 (52%) 

2 (3%) 

24 (36%) 40 (61%) 

1 (1%) 2 (3%) 

65 (97%) 66 (100%) 

12 (18%) 22 (33%) 

1 (2%) 

(69) 

1 (1%) 

1 (1%) 

55 (80%) 

40 (58%) 

68 (99%) 

43 (62%) 
260 Nickel Oxide, NTP TR 451 

TABLE C5 

Summary of the Incidence of Nonneoplastic Lesions in Male Mice in the 2-Year Inhalation Study of Nickel Oxide 

(continued) 

0 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 5 mg/m 3 

2-Year Study (continued) 

Respiratory System (continued) 

Nose 

Inflammation, suppurative 

Olfactory epithelium, degeneration 

Olfactory epithelium, inflammation, 

suppurative 

Respiratory epithelium, degeneration 

Respiratory epithelium, inflammation, 

suppurative 

Respiratory epithelium, metaplasia, squamous 

Vomeronasal organ, inflammation, suppurative 

(55) 

2 (4%) 

6 (11%) 

2 (4%) 

(66) (66) (67) 

2 (3%) 1 (2%) 

4 (6%) 2 (3%) 1 (1%) 

2 (3%) 

3 (5%) 4 (6%) 1 (1%) 

9 (14%) 9 (14%) 7 (10%) 

7 (11%) 8 (12%) 2 (3%) 

1 (2%) 

Special Senses System 

Harderian gland 

Hyperplasia 

(1) (2) (3) 

1 (33%) 

Urinary System 

Kidney (57) (67) (66) (68) 

Atrophy 1 (2%) 

Fibrosis 1 (1%) 

Inflammation, chronic 2 (3%) 1 (1%) 

Inflammation, chronic active 1 (2%) 6 (9%) 1 (1%) 

Inflammation, suppurative 1 (1%) 4 (6%) 6 (9%) 

Mineralization 1 (2.%) 1 (1%) 

Necrosis 1 (2%) 

Nephropathy 1 (2%) 1 (1%) 3 (5%) 1 (1%) 

Bilateral, inflammation, suppurative 1 (2%) 

Bilateral, papilla, inflammation, suppurative 1 (2%) 

Bilateral, pelvis, dilatation 1 (2%) 

Cortex, cyst 1 (2%) 1 (1%) 2 (3%) 

Cortex, fibrosis 1 (2%) 

Cortex, inflammation, chronic 1 (2%) 

. Pelvis, dilatation 9 (16%) 6 (9%) 9 (14%) 5 (7%) 

Pelvis, hyperplasia, squamous 1 (1%) 

Pelvis, inflammation, chronic 1 (2%) 

Pelvis, inflammation, chronic active 1 (1%) I (1%) 

Pelvis, inflammation, suppurative 2 (4%) 1 (1%) 1 (1%) 

Renal tubule, mineralization 2 (3%) 

Ureter (2) (4) 

Concretion 2 (50%) 

Inflammation, chronic active I (25%) 

Inflammation, suppurative 1 (50%) 1 (25%) 

Urethra (2) (4) (5) (12) 

Calculus, microscopic observation only 1 (50%) 3 (75%) 4 (80%) 8 (67%) 

Concretion 1 (50%) 1 (25%) 1 (20%) 4 (33%) 
Lesions in Male Mice 261 

TABLE C5 

Summary of the Incidence of Nonneoplastic Lesions in Male Mice in the 2-Year Inhalation Study of Nickel Oxide 

(continued) 

0 mg/m 3 1.25 mg/m 3 2.5 mg/m ~ 5 mg/m 3 

2-Year Study (continued) 

Urinary System (continued) 

Urinary bladder (54) 

Calculus, gross observation 

Calculus, microscopic observation only 1 (2%) 

Crystals 

Hemorrhage 

Inflammation 

Inflammation, chronic 1 (2%) 

Inflammation, chronic active 1 (2%) 

Inflammation, suppurative 2 (4%) 

Transitional epithelium, hyperplasia 1 (2%) 

Transitional epithelium, metaplasia, squamous 1 (2%) 

(63) (65) (66) 

1 (2%) 

3 (5%) 3 (5%) 1 (2%) 

1 (2%) 

1 (2%) 

1 (2%) 

1 (2%) 1 (2%) 

2 (3%) 2 (3%) 1 (2%) 

5 (8%) 2 (3%) 4 (6%) 

3 (5%) 

1 (2%) 

a Number of animals examined microscopically at site and number of animals with lesion 

b No histopathologic examination was performed on these animals. 

e This alteration is associated with injury to the parenchyma around the terminal bronchiole. It is listed as "alveolar epithelial hyperplasia" in the TDMS 

data tables for mice in this study. 
262 Nickel Oxide, NTP TR 451 
263 

APPENDIX D 

SUMMARY OF LESIONS IN FEMALE MICE 

IN THE 2-YEAR INHALATION STUDY 

OF NICKEL OXIDE 

TABLE DI 

TABLE D2 

TABLE D3 

TABLE D4 

TABLE D5 

Summary of the Incidence of Neoplasms in Female Mice 

in the 2-Year Inhalation Study of Nickel Oxide .......................... 264 

Individual Animal Tumor Pathology of Female Mice 

in the 2-Year Inhalation Study of Nickel Oxide .......................... 271 

Statistical Analysis of Primary Neoplasms in Female Mice 

in the 2-Year Inhalation Study of Nickel Oxide .......................... 304 

Historical Incidence of Alveolar/bronchiolar Neoplasms 

in Untreated Female B6C3F1 Mice ................................... 309 

Summary of the Incidence of Nonneoplastic Lesions in Female Mice 

in the 2-Year Inhalation Study of Nickel Oxide .......................... 310 
264 Nickel Oxide, NTP TR 451 

TABLE D1 

Summary of the Incidence of Neoplasms in Female Mice in the 2-Year Inhalation Study of Nickel Oxide a 

0 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 5 mg/m 3 

Disposition Summary 

Animals initially in study 74 76 74 

7-Month interim evaluation 5 5 5 

15-Month interim evaluation 5 5 5 

Early deaths 

Accidental deaths 1 1 

Moribund 15 18 9 

Natural deaths 7 8 11 

Survivors 

Terminal sacrifice 40 38 42 

Died last week of study 1 2 

Pregnant/Missexed 1 

Animals examined microscopically 74 76 73 

75 

5 

5 

16 

10 

38 

1 

74 

Systems Examined At 7 Months With No Neoplasms Observed 

Alimentary System 

Cardiovascular System 

Endocrine System 

General Body System 

Genital System 

Hematopoietic System 

Integumentary System 

Musculoskeletal System 

Nervous System 

Respiratory System 

Special Senses System 

Urinary System 

15-Month Interim Evaluation 

Alimentary System 

Liver 

Hepatocellular adenoma 

(5) (5) 

1 (20%) 

(5) (5) 

Respiratory System 

Lung 

Alveolar/bronchiolar adenoma 

(5) (5) (5) 

1 (20%) 

(5) 
Lesions in Female Mice 265 

TABLE D1 

Summary of the Incidence of Neoplasms in Female Mice in the 2-Year Inhalation Study of Nickel Oxide 

(continued) 

0 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 5 mg/m 3 

15-Month Interim Evaluation (continued) 

Systems Examined With No Neoplasms Observed 

Cardiovascular System 

Endocrine System 

General Body System 

Genital System 

Hematopoietic System 

Integumentary System 

Musculoskeletai System 

Nervous System 

Special Senses System 

Urinary System 

2- Year Study 

Alimentary System 

Esophagus (63) 

Squamous cell carcinoma 

Gallbladder (60) 

Sarcoma, metastatic, mesentery 

Intestine large, colon (60) 

Hepatocholangiocarcinoma, metastatic, liver 

Intestine large, .rectum (55) 

Intestine large, cecum (60) 

Leiomyosarcoma. 

Sarcoma, metastatic, mesentery 

Intestine small, duodenum (60) 

Hepatocholangiocarcinoma, metastatic, liver 

Intestine small, jejunum (59) 

Intestine small, ileum (58) 

Liver (64) 

Hemangiosarcoma 

Hemangiosarcoma, multiple 

Hemangiosarcoma, metastatic, uterus 

Hepatocellular carcinoma 7 (11%) 

Hepatocellular carcinoma, multiple 1 (2 %) 

Hepatocel!ular adenoma 5 (8 %) 

Hepatocellular adenoma, multiple 

Hepatocellular adenoma, multiple, multiple 1 (2%) 

Hepatocholangiocarcinoma 

Histiocytic sarcoma 1 (2%) 

Sarcoma, metastatic, mesentery 

Mesentery (2) 

Hemangiosarcoma 1 (50%) 

Hepatocholangiocarcinoma, metastatic, liver 

Sarcoma 

Pancreas (64) 

Hepatocholangiocarcinoma, metastatic, liver 

Sarcoma, metastatic, mesentery 

Salivary glands (64) 

(66) 

(59) 

(61) 

(50) 

(60) 

(60) 

(59) 

(57) 

(66) 

1 

1 

10 

(2) 

(66) 

(66) 

(2%) 

(~%) 

(15%) 

(ll%) 

(63) 

(57) 

(58) 

(43) 

(57), 

(56) 

(56) 

(56) 

(63) 

1 (2%) 

8 03%) 

8 (13%) 

1 (2%) 

(~) 

(62) 

(63) 

(63) 

1 (2%) 

(56) 

1 (2%) 

(57) 

1 (2%) 

(43) 

(56) 

1 (2%) 

1 (2%) 

(56) 

1 (2%) 

(56) 

(54) 

(63) 

l (2%) 

4 (6%) 

5 (8%) 

1 (2%) 

2 (3%) 

1 (2%) 

(3) 

1 (33%) 

1 (33%) 

(62) 

1 (2%) 

1 (2%) 

(63) 
266 Nickel Oxide, NTP TR 451 

TABLE D1 

Summary of the Incidence of Neoplasms in Female Mice in the 2-Year Inhalation Study of Nickel Oxide 

(continued) 

0 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 5 mg/m 3 

2-Year Study (continued) 

Alimentary System (continued) 

Stomach, forestomach (64) 

Sarcoma, metastatic, mesentery 

Squamous cell carcinoma 1 (2%) 

Squamous cell papilloma 1 (2%) 

Stomach, glandular (63) 

Hepatocholangiocarcinoma, metastatic, liver 

Sarcoma, metastatic, mesentery 

Tooth (2) 

Odontoma 

(63) (62) (60) 

1 (2%) 

(63) (62) 

(1) (1) 

1 (2%) 

(60) 

1 (2%) 

1 (2%) 

(2) 

1 (50%) 

Cardiovascular System 

Heart (64) 

Alveolar/bronchiolar carcinoma, metastatic, 

lung 1 (2%) 

Hepatocholangiocarcinoma, metastatic, liver 

(66) (63) (64) 

1 (2%) 

Endocrine System 

Adrenal cortex (64) (66) (63) (62) 

Adenoma 1 

Hepatocholangiocarcinoma, metastatic, liver 1 

Adrenal medulla (62) (65) (63) (62) 

Pheochromocytoma malignant 2 (3%) 

Pheochromocytoma benign 1 (2%) I (2%) 

Islets, pancreatic (63) (65) (62) (62) 

Pituitary gland (63) (66) (61) (62) 

Pars distalis, adenoma 6 (10%) 9 (14%) 8 (13%) 6 

Pars distalis, carcinoma 1 (2%) 1 

Pars intermedia, adenoma 1 (2%) 1 (2%) i 

Thyroid gland (62) (66) (63) (64) 

Bilateral, follicular cell, adenoma 1 (2%) 

Follicular cell, adenoma 2 (3%) 1 (2%) 1 

Follicular cell, carcinoma 1 (2%) 

(2%) 

(2%) 

(lO%) 

(2%) 

(2%) 

(2%) 

General Body System 

Tissue NOS 

Alveolar/bronchiolar carcinoma, metastatic, 

lung 

Hemangiosarcoma, metastatic 

Fat, hemangiosarcoma 

Thoracic, alveolar/bronchiolar carcinoma, 

metastatic, tung 

(1) 

1 (1oo%) 

(1) 

1 (100%) 

(1) 

1 (100%) 

(1) 

(100%) 
Lesions in Female Mice 267 

TABLE D1 

Summary of the Incidence of Neoplasms in Female Mice in the 2-Year Inhalation Study of Nickel Oxide 

(continued) 

0 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 5 mg/m a 

2-Year Study (continued) 

Genital System 

Clitoral gland (57) (62) 

Duct, adenoma 1 (2%) 

Ovary (61) (66) 

Cystadenoma 1 (2%) 

Granulosa-theca tumor benign 

Sarcoma, metastatic, mesentery 

Teratoma benign 2 (3%) 1 (2%) 

Teratoma malignant 

Thecoma benign 1 (2%) 

Uterus (64) (66) 

Carcinoma 1 (2%) 

Hemangioma 

Hemangiosarcoma 2 (3%) 

Histiocytic s~ircoma 1 (2%) 

Leiomyoma 1 (2%) 

Polyp stromal 2 (3%) 4 (6%) 

Sarcoma, metastatic, mesentery 

Sarcoma stromal 1 (2%) 

Teratoma malignant, metastatic 

Cervix, hemangiosarcoma 1 (2%) 

(57) (55) 

(60) (63) 

3 (5%) 

I (2%) 

! (2%) 

! (2%) 

(62) (63) 

1 (2%) 

1 (2%) 1 (2%) 

1 (2%) 

1 (2%) 

1 (2%) 

1 (2%) 

Hematopoietic System 

Bone marrow (64) 

Hemangiosarcoma 

Hemangiosarcoma, metastatic 

Hemangiosarcoma, metastatic, spleen 

Lymph node (15) 

Axillary, hemangiosarcoma 1 (7%) 

Pancreatic, histiocytic sarcoma 

Pancreatic, sarcoma, metastatic, mesentety 

Renal, sarcoma, metastatic, mesentery 

Lymph node, bronchial (54) 

Alveolar/bronchiolar carcinoma, metastatic, 

lung 1 (2%) 

Histiocytic sarcoma 

Sarcoma, metastatic, mesentery 

Lymph node, mandibular (61) 

Sarcoma, metastatic, skin 

Lymph node, mesenteric (54) 

Hemangioma 

Hemangiosarcoma, metastatic, liver 

Hepatocholangiocarcinoma, metastatic, liver 

Sarcoma, metastatic, mesentery 

Lymph node, mediastinal (35) 

Alveolar/bronchiolar carcinoma, metastatic 

Alveolar/bronchiolar carcinoma, metastatic, 

lung 1 (3%) 

Hepatocholangiocarcinoma, metastatic, liver 

Histiocytic sarcoma 

Sarcoma, metastatic, mesentery 

(65) 

(9) 

(63) 

2 (3%) 

(63) 

1 (2%) 

(63) 

(28) 

1 (4%) 

1 (4%) 

(62) (63) 

~ (2%) 

1 (2%) 

1 (2%) 

(10) (9) 

1 (10%) 

1 (11%) 

1 (11%) 

I (11%) 

(59) (62) 

2 (3%) 

i (2%) 

(59) (58) 

(54) (55) 

! (2%) 

1 (2%) 

(33) 

1 (2%) 

1 (2%) 

(29) 

1 (3%) 

1 (3%) 

1 (3%) 
268 Nickel Oxide, NTP TR 451 

TABLE D1 

Summary of the Incidence of Neoplasms in Female Mice in the 2-Year Inhalation Study of Nickel Oxide 

(continued) 

0 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 5 mg/m 3 

2-Year Study (continued) 

Itematopoietic System (continued) 

Spleen 

Hemangiosarcoma 

Hepatocholangiocarcinoma, metastatic, liver 

Histiocytic sarcoma 

Sarcoma, metastatic, mesentery 

Thymus 

Alveolar/bronchiolar carcinoma, metastatic 

Alveolar/bronchiolar carcinoma, metastatic, 

lung 

Hepatocholangiocarcinoma, metastatic, liver 

Histiocytic sarcoma 

Sarcoma, metastatic, mesentery 

(64) (66) 

2 (3%) 2 (3%) 

(59) (61) 

1 (2%) 

2 (3%) 

1 (2%) 

1 (2%) 

(63) (63) 

5 (8%) 2 (3%) 

1 (2%) 

2 (3%) 

1 (2%) 

(60) (57) 

1 (2%) 

1 (2%) 

1 (2%) 

Integumentary System 

Mammary gland (63) (66) 

Adenoma 1 (2%) 

Carcinoma 2 (3%) 3 (5%) 

Skin (4) (8) 

Hemangiosarcoma 1 (13%) 

Melanoma NOS 1 (13%) 

Sarcoma 1 (13%) 

Squamous cell papilloma 

Pinna, sarcoma 1 (13%) 

Sebaceous gland, adenoma 

Subcutaneous tissue, hemangiosarcoma 1 (25%) 1 (13%) 

(63) (63) 

3 (5%) 

(6) (12) 

1 (17%) 1 (8%) 

1 (8%) 

1 (17%) 

Musculoskeletal System 

Bone (64) 

Alveolar/bronchiolar carcinoma, metastatic, 

lung 

Skeletal muscle (3) 

Alveolar/bronchiolar carcinoma, metastatic, 

lung 1 (33%) 

Hepatocholangiocarcinoma, metastatic, liver 

Rhabdomyosarcoma I (33%) 

Sarcoma, metastatic, mesentery 

(65) 

1 (2%) 

(63) (63) 

(3) 

1 (33%) 

1 (33%) 

Nervous System 

Brain (64) 

Carcinoma, metastatic 1 (2%) 

Hypothalamus, carcinoma, metastatic 

Pons, carcinoma, metastatic 

(66) (63) (64) 

1 (2%) 

1 (2%) 
Lesions in Female Mice 269 

TABLE DI 

Summary of the Incidence of Neoplasms in Female Mice in the 2-Year Inhalation Study of Nickel Oxide 

(continued) 

0 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 5 mg/m a 

2-Year Study (continued) 

Respiratory System 

Larynx (62) 

Lung (64) 

Alveolar/bronchiolar adenoma 2 (3%) 

Alveolar/bronchiolar adenoma, multiple 

Alveolar/bronchiolar carcinoma 4 (6 %) 

Alveolar/bronchiolar carcinoma, multiple 

Basosquamous tumor malignant, metastatic, ear 1 (2%) 

Hepatocellular carcinoma, metastatic 

Hepatocellular carcinoma, metastatic, liver 1 (2%) 

Hepatocholangiocarcinoma, metastatic, liver 

Histiocytic sarcoma 

Sarcoma, metastatic, mesentery 

Teratoma malignant, metastatic 

(63) (62) (63) 

(66) (63) (64) 

2 (3%) 10 (16%) 3 (5%) 

2 (3%) 

10 (15%) 4 (6%) 5 (8%) 

1 (2%) 

1 (2%) 1 (2%) 1 (2%) 

1 (2%) 

2 (3%) 

1 (2%) 

I (2%) 

Special Senses System 

Ear 

Basosquamous minor malignant 

Fibrosarcoma 

External ear, fibrosarcoma 

Harderian gland 

Adenoma 

(2) 

1 (50%) 

1 (50%) 

(1) 

(I) 

1 (100%) 

(1) 

1 (lOO%) 

(2) 

2 (100%) 

(1) 

(3) 

3 (1oo%) 

Urinary System 

Kidney (64) 

Hepatocholangiocarcinoma, metastatic, liver 

Teratoma malignant, metastatic 

Urinary bladder (63) 

Sarcoma, metastatic, mesentery 

(66) 

(62) 

(63) 

(60) 

(63) 

1 (2%) 

1 (2%) 

(57) 

1 (2%) 

Systemic Lesions 

Multiple organs b 

Histiocytic sarcoma 

Lymph~ma malignant 

(64) 

2 (3%) 

13 (20%) 

(66) 

12 (18%) 

(63) 

9 (14%) 

(64) 

2 (3%) 

7 (11%) 
270 Nickel Oxide, NTP TR 451 

TABLE D1 

Summary of the Incidence of Neoplasms in Female Mice in the 2-Year Inhalation Study of Nickel Oxide 

(continued) 

0 mg/m ~ 1.25 mg/m 3 2.5 mg/m 3 5 mg/m 3 

Neoplasm Summary 

Total animals with primary neoplasms c 

15-Month interim evaluation 1 1 

2-Year study 37 49 45 40 

Total primary neoplasms 

15-Month interim evaluation 1 1 

2-Year study 68 78 72 57 

Total animals with benign neoplasms 

15-Month interim evaluation 1 1 

2-Year study 21 27 28 24 

Total benign neoplasms 

15-Month interim evaluation 1 1 

2-Year study 25 30 38 25 

Total animals with malignant neoplasms 

2-Year study 30 37 28 28 

Total malignant neplasms 

2-Year study 43 47 34 32 

Total animals with metastatic neoplasms 

2-Year study 5 6 3 6 

Total metastatic neoplasms 

2-Year study 10 11 3 40 

Total animals with uncertain neoplasmsbenign or malignant 

2-Year study 1 

Total uncertain neoplasms 

2-Year study 1 

a Number of animals examined microscopically at the site and the number of animals with neoplasm 

b Number of animals with any tissue examined microscopically 

c Primary neoplasms: all neoplasms except metastatic neoplasms 
Lesions in Female Mice 271 

TABLE D2 

Individual Animal Tumor Pathology of Female Mice in the 2-Year Inhalation Study of Nickel Oxide: 0 mg/m s 

Number of Days on Study 

0000011235555566666667777 

1122913251458912348992222 

1449272970996982828458899 

Carcass ID Number 

1011101010111011011110100 

2930080818512834903309189 

0526865701448344098706399 

Alimentary System 

Esophagus 

Gallbladder 

Intestine large, colon 

Intestine large, rectum 

Intestine large, cecum 

Intestine small, duodenum 

Intestine small, jejunum 

Intestine small, ileum 

Liver 

Hepatocellular carcinoma 

Hepatocellular carcinoma, multiple 

Hepatocellular adenoma 

Hepatocellular adenoma, multiple, multiple 

Histiocytic sarcoma 

Mesentery 

Hemangiosarcoma 

Pancreas 

Salivary glands 

Stomach, forestomach 

Squamous cell carcinoma 

Squamous cell papilloma 

Stomach, glandular 

Tooth 

+ + + + +M+ + + + + + + + + + + + + + + + + + + 

+ +AA + + + + + + +M+ + + + + + + + + + + + + 

+ +AM+ + + + + + + + + +A + + + + + + + + + + 

+ +A + +M+ +M+ + + + +MMM+ + + + + + + + 

++AM++ ++ + ++ ++ +A + + + + ++ + + + + 

+ +AM+ +++ + + +++ +A + + + +++ + + + + 

+ +AM+ + + + + + + + + +A + + + + +A + + + + 

+ +AM+ + + + + + + +M+A + + + + + + +M+ + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X X 

X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

Cardiovascular System 

Heart 

Alveolar/bronchiolar carcinoma, 

metastatic, lung 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

Endocrine System 

Adrenal cortex 

Adrenal medulla 

Pheochromocytoma malignant 

Pheochromocytoma benign 

Islets, pancreatic 

Parathyroid gland 

Pituitary gland 

Pars distalis, adenoma 

Pars distalis, carcinoma 

Thyroid gland 

Follicular cell, adenoma 

Follicular cell, carcinoma 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

++M+I ++ +++ + + + ++ + + ++ + + + + + + 

X X 

+ + + + + + + + + + + + + + + + + + + + + + +M+ 

MMM+ +MMM+ ++M+ + ++ + ++I + + +MM 

+ + + + + + + + + + + + + + + + +M+ + + + + + + 

X 

X 

+ +M+ +M+ + + + + + + + + + + + + + + + + + + 

X 

+: Tissue examined microscopically M: Missing tissue X: Lesion present 

A: Autolysis precludes examination I: Insufficient tissue Blank: Not examined 
272 Nickel Oxide, NTP TR 451 

TABLE D2 

Individual Animal Tumor Pathology of Female Mice in the 2-Year Inhalation Study of Nickel Oxide: 0 mg/m 3 

(continued) 

Number of Days on Study 

7777777777777777777777777 

2222233333333333333333333 

9999900000000011111112222 

Carcass ID Number 

1111100011111111111110111 

1245589902344623345559011 

5722323713615015 96168 1318 

Alimentary System 

Esophagus 

Gallbladder 

Intestine large, colon 

Intestine large, rectum 

Intestine large, cecum 

Intestine small, duodenum 

Intestine small, jejunum 

Intestine small, ileum 

Liver 

Hepatocellular carcinoma 

Hepatocellular carcinoma, multiple 

Hepatocellular adenoma 

Hepatocellular adenoma, multiple, multiple 

Histiocytic sarcoma 

Mesentery 

Hemangiosarcoma 

Pancreas 

Salivary glands 

Stomach, forestomach 

Squamous cell carcinoma 

Squamous cell papilloma 

Stomach, glandular 

Tooth 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + +A + + + + + + + + + + + + 

+ + + + + + + + + + + +A + + + + + + + + + + + + 

+ ++ + +++++ +M+A + +++ + + +M+ + ++ 

+ + + + + + + + + + + + A + + + + + + + + + + + + 

++++++ ++++++A ++++ + + ++ + ++ + 

+ + + + + + + + + + + + A + + + + + + + + + + + + 

+ + + + + + + + + + + + A + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X X X 

X X X X X 

X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + 

Cardiovascular System 

Heart 

Alveolar/bronchiolar carcinoma, 

metastatic, lung 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

Endocrine System 

Adrenal cortex 

Adrenal medulla 

Pheochromocytoma malignant 

Pheochromocytoma benign 

Islets, pancreatic 

Parathyroid gland 

Pituitary gland 

Pars distalis, adenoma 

Pars distalis, carcinoma 

Thyroid gland 

Follicular cell, adenoma 

Follicular cell, carcinoma 

X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

I +M++ +++ ++ + + +M++ + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X X X 

X 
Lesions in Female Mice 273 

TABLE D2 

Individual Animal Tumor Pathology of Female Mice in the 2-Year Inhalation Study of Nickel Oxide: 0 mg/m 3 

(continued) 

Number of Days on Study 

77777777777777 

33333333333333 

22222333336666 

Carcass ID Number 

11111111110111 

12334012259145 

99017224604699 

Total 

Tissues/ 

Tumors 

Alimentary System 

Esophagus 

Gallbladder 

Intestine large, colon 

Intestine large, rectum 

Intestine large, cecum 

Intestine small, duodenum 

Intestine small, jejunum 

Intestine small, ileum 

Liver 

Hepatocellular carcinoma 

Hepatocellular carcinoma, multiple 

Hepatocellular adenoma 

Hepatocellular adenoma, multiple, multiple 

Histiocytic sarcoma 

Mesentery 

Hemangiosarcoma 

Pancreas 

Salivary glands 

Stomach, forestomach 

Squamous cell carcinoma 

Squamous cell papilloma 

Stomach, glandular 

Tooth 

+ + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + 

X X 

X 

+ 

X 

+ + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + 

M++++++++ +++++ 

63 

60 

60 

55 

60 

60 

59 

58 

64 

7 

1 

5 

1 

1 

2 

1 

64 

64 

64 

1 

1 

63 

2 

Cardiovascular System 

Heart 

Alveolar/bronchiolar carcinoma, 

metastatic, lung 

+ + + + + + + + + + + + + + 

1 

Endocrine System 

Adrenal cortex 

Adrenal medulla 

Pheochromocytoma malignant 

Pheochromocytoma benign 

Islets, pancreatic 

Parathyroid gland 

Pituitary gland 

Pars distalis, adenoma 

Pars distalis, carcinoma 

Thyroid gland 

Follicular cell, adenoma 

Follicular cell, carcinoma 

+ + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + 

+++++M++++++++ 

+ + + + + + + + + + + + + + 

X X 

X 

64 

62 

2 

1 

63 

50 

63 

6 

1 

62 

2 

1 
274 Nickel Oxide, NTP TR 451 

TABLE D2 

Individual Animal Tumor Pathology of Female Mice in the 2-Year Inhalation Study of Nickel Oxide: 0 mg/m 3 

(continued) 

Number of Days on Study 

0000011235555566666667777 

1122913251458912348992222 

1449272970996982828458899 

Carcass ID Number 

10 I 1101010111011011110100 

2930080818512834903309189 

0526865701448344098706399 

General Body System 

Tissue NOS 

Thoracic, alveolar/bronchiolar 

carcinoma, metastatic, lung 

Genital System 

Clitoral gland 

Ovary 

Cystadenoma 

Teratoma benign 

Thecoma benign 

Uterus 

Histiocytic sarcoma 

Leiomyoma 

Polyp stromal 

Sarcoma stromal 

+M+ + ++MM+ + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

XX 

X 

+ + + + + + + + + + + + + + ÷ + + + + + + + + + + 

X 

Hematopoietic System 

Bone marrow 

Lymph node 

Axillary, hemangiosarcoma 

Lymph node, bronchial 

Alveolar/bronchiolar carcinoma, 

metastatic, lung 

Lymph node, mandibular 

Lymph node, mesenteric 

Lymph node, mediastinal 

Alveolar/bronchiolar carcinoma, 

metastatic, lung 

Spleen 

Hemangiosarcoma 

Thymus 

Alveolar/bronchiolar carcinoma, 

metastatic, lung 

Histiocytic sarcoma 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ +++ +++ 

X 

MMM+MI M+M+I + +I ++ + + + + + + + + + 

+ + + + + + + + + + + + +M+ + + + +M+ + + + 

M+MAM+M+ + +M+ + + +M+ + + +M+ + + + 

MMMMMMMMM+M+MMMM+M+M+ + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

+ + + +M+M+ + + + + + +I + + + + +M+ + + + 

X 

Integumentary System 

Mammary gland 

Carcinoma 

Skin 

Subcutaneous tissue, hemangiosar¢oma 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

++ 

Musculoskeletal System 

Bone 

Skeletal muscle 

Alveolar/bronchiolar carcinoma, 

metastatic, lung 

Rhabdomyosarcoma 

X 
Lesions in Female Mice 275 

TABLE D2 

Individual Animal Tumor Pathology of Female Mice in the 2-Year Inhalation Study of Nickel Oxide: 0 mg/m 3 

(continued) 

Number of Days on Study 

7777777777777777777777777 

2222233333333333333333333 

9999900000000011111112222 

Carcass ID Number 

1111100011111111111110111 

1245589902344623345559011 

5722323713615015961681318 

General Body System 

Tissue NOS 

Thoracic, alveolar/bronchiolar 

carcinoma, metastatic, lung 

Genital System 

Clitoral gland 

Ovary 

Cystadenoma 

Teratoma benign 

Thecoma benign 

Uterus 

Histiocytic sarcoma 

Leiomyoma 

Polyp stromal 

Sarcoma stromal 

+ + + + + + +I I + + +M+ + + + + + + +M+ + + 

+ + + + + + + + + + +M+ + + + +M+ + + + +I + 

X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

Hematopoietic System 

Bone marrow 

Lymph node 

Axillary, hemangiosarcoma 

Lymph node, bronchial 

Alveolar/bronchiolar carcinoma, 

metastatic, lung 

Lymph node, mandibular 

Lymph node, mesenteric 

Lymph node, mediastinal 

Alveolar/bronchiolar carcinoma, 

metastatic, lung 

Spleen 

Hemangiosarcoma 

Thymus 

Alveolar/bronchiolar carcinoma, 

metastatic, lung 

Histiocytic sarcoma 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + 

+ +I + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ ++ + ++ + + + ++ +M+ + + + + + + ++ ++ + 

+MM+ +MM+ +M+M+MMM+ +M+ + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

Integumentary System 

Mammary gland 

Carcinoma 

Skin 

Subcutaneous tissue, hemangiosarcoma 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ 

X 

Musculoskeletal System 

Bone 

Skeletal muscle 

Alveolar/bronchiolar carcinoma, 

metastatic, lung 

Rhabdomyosarcoma X 
276 Nickel Oxide, NTP TR 451 

TABLE D2 

Individual Animal Tumor Pathology of Female Mice in the 2-Year Inhalation Study of Nickel Oxide: 0 mg/m 3 

(continued) 

Number of Days on Study 

77777777777777 

33333333333333 

22222333336666 

Carcass ID Number 

11111111110111 

12334012259145 

99017224604699 

Total 

Tissues/ 

Tumors 

General Body System 

Tissue NOS 

Thoracic, alveolar/bronchiolar 

carcinoma, metastatic, lung 

+ 

X 

Genital System 

Clitoral gland 

Ovary 

Cystadenoma 

Teratoma benign 

Thecoma benign 

Uterus 

Histiooytic sarcoma 

Leiomyoma 

Polyp stromal 

Sarcoma stromal 

+ + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + 

X 

X 

57 

61 

1 

2 

1 

64 

1 

1 

2 

1 

Hematopoietic System 

Bone marrow 

Lymph node 

Axillary, hemangiosarcoma 

Lymph node, bronchial 

Alveolar/bronchiolar carcinoma, 

metastatic, lung 

Lymph node, mandibular 

Lymph node, mesenteric 

Lymph node, mediastinal 

Alveolar/bronchiolar carcinoma, 

metastatic, lung 

Spleen 

Hemangiosarcoma 

Thymus 

Alveolar/bronchiolar carcinoma, 

metastatic, lung 

Histiocytic sarcoma 

+ + + + + + + + + + + + + + 

+ + ++ 

+ + + + + + + + + + + + + + 

X 

+ + + + + + + + + + + + + + 

+ + +M+ + + + + + + + + + 

+ + + + + + +M+ +M+ +M 

X 

+ + + + + + + + + + + + + + 

++ + + + +++M+ + + + + 

X 

64 

15 

1 

54 

1 

61 

54 

35 

1 

64 

2 

59 

Integumentary System 

Mammary gland 

Carcinoma 

Skin 

Subcutaneous tissue, hemangiosarcoma 

+M+ +++ + + + ++ + + + 

X 

+ 

63 

2 

4 

1 

Musculoskeletal System 

Bone 

Skeletal muscle 

Alveolar/bronchiolar carcinoma, 

metastatic, lung 

Rhabdomyosarcoma 

+ + ÷ + + + ÷ + + + ÷ + + ÷ 64 

3 
Lesions in Female Mice 277 

TABLE D2 

Individual Animal Tumor Pathology of Female Mice in the 2-Year Inhalation Study of Nickel Oxide: 0 mg/m 3 

(continued) 

Number of Days on Study 

0000011235555566666667777 

1122913251458912348992222 

1449272970996982828458899 

Carcass ID Number 

I 011101010111011011110100 

2930080818512834903309189 

0526865701448344098706399 

Nervous System 

Brain 

Carcinoma, metastatic 

+ + + + + + + + ÷ + + + + + + + + + + + + + + ÷ + 

X 

Respiratory System 

Larynx 

Lung 

Alveolar/bronchiolar adenoma 

Alveolar/bronchiolar carcinoma 

Basosquamous tumor malignant, 

metastatic, ear 

Hepatocelltdar carcinoma, metastatic, liver 

Nose 

Trachea 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + W + + + + + + + + + + 

X 

X 

X 

+ + + +AA + + + + + + + + + + + + + + + + + + + 

+ +I + + + + + + + + + + + + + + + + + + + + + + 

Special Senses System 

Ear 

Basosquamous tumor malignant 

External ear, fibrosarcoma 

÷ 

X 

Urinary System 

Kidney 

Urinary bladder 

+ + + + + + + + + + + + + + + ~ + + + + + + + + + 

+ +A + + + + + + + + + + + + + + + + + + + + + + 

Systemic Lesions 

Multiple organs 

Histiocytic sarcoma 

Lymphoma malignant X X XXX 
278 Nickel Oxide, NTP TR 451 

TABLE D2 

Individual Animal Tumor Pathology of Female Mice in the 2-Year Inhalation Study of Nickel Oxide: 0 mg/m 3 

(continued) 

Number of Days on Study 

7777777777777777777777777 

2222233333333333333333333 

9999900000000011111112222 

Carcass ID Number 

1111100011111111111110111 

1245589902344623345559011 

5722323713615015961681318 

Nervous System 

Brain 

Carcinoma, metastatic 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

Respiratory System 

Larynx 

Lung 

Alveolar/bronchiolar adenoma 

Alveolar/bronchiolar carcinoma 

Basosquamous tumor malignant, 

metastatic, ear 

Hepatocellular carcinoma, metastatic, liver 

Nose 

Trachea 

+.+ + + + + + + + + + + + + + + + + + +M+ + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X X 

X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

Special Senses System 

Ear 

Basosquamous tumor malignant 

External ear, fibrosarcoma 

+ 

X 

Urinary System 

Kidney 

Urinary bladder 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

Systemic Lesions 

Multiple organs 

Histiocytic sarcoma 

Lymphoma malignant 

X 

X X X X XX 
Lesions in Female Mice 279 

TABLE D2 

Individual Animal Tumor Pathology of Female Mice in the 2-Year Inhalation Study of Nickel Oxide: 0 mg/m 3 

(continued) 

Number of Days on Study 

77777777777777 

33333333333333 

22222333336666 

Carcass ID Number 

11111111110111 

12334012259145 

99017224604699 

Total 

Tissues/ 

Tumors 

Nervous System 

Brain 

Carcinoma, metastatic 

,+ + + + + + + + + + + + + + 64 

1 

Respiratory System 

Larynx 

Lung 

Alveolar/bronchiolar adenoma 

Alveolar/bronchiolar carcinoma 

Basosquamous tumor malignant, 

metastatic, ear 

Hepatocellul~r carcinoma, metastatic, liver 

Nose 

Trachea 

+M+ + + + + + + + + + + + 

+ + + + + + + + + + + + + + 

X 

X 

+ + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + 

62 

64 

2 

4 

1 

1 

62 

63 

Special Senses System 

Ear 

Basosquamous tumor malignant 

External ear, fibrosarcoma 

Urinary System 

Kidney 

Urinary bladder 

+ + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + 

64 

63 

Systemic Lesions 

Multiple organs 

Histiocytic sarcoma 

Lymphoma malignant 

+ + + + + + + + + + + + + + 

X 

X X 

64 

2 

13 
280 Nickel Oxide, NTP TR 451 

TABLE D2 

Individual Animal Tumor Pathology of Female Mice in the 2-Year Inhalation Study of Nickel Oxide: 1.25 mg/m 3 

Number of Days on Study 

0123455555666666666666677 

4601616899002445578899912 

6237906337396042763302510 

Carcass ID Number 

3322232222222223222223223 

0299514964858770677980591 

8014974047765514067386476 

Alimentary System 

Esophagus 

Gallbladder 

Intestine large, colon 

Intestine large, rectum 

Intestine large, cecum 

Intestine small, duodenum 

Intestine small, jejunum 

Intestine small, ileum 

Liver 

Hemangiosareoma, multiple 

Hemangiosarcoma, metastatic, uterus 

I-~epatocellular carcinoma 

Hepatocellular adenoma 

Mesentery 

Pancreas 

Salivary glands 

Stomach, forestomach 

Stomach, glandular 

Tooth 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

A + + +A + +A +A + + + + +AA + + + + +M+ + 

A + + +A + +A +A + + + + + +A + + + + + + + + 

A + + +A + + + +A + + + + + +M+M+ + +M+ + 

A + + +A + +A +A + + + + +AA + + + + + + + + 

A + + +A + +A +A + + + + +A + + + + + +A + + 

A + + +A + +A +A + + + + +A A + + + + +A + + 

A + + +A + +A +A + +'+ + +AA + + + + +AM+ 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

X X X X X 

X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

A + + + + + + + +A + + + + +A + + + + + + + + + 

A + + + + + + + +A + + + + +A + + + + + + + + + 

Cardiov~cular System 

Hea~ + + + + + + + + + + + + + + + + + + + + + + + + + 

Endocrine System 

Adrenal cortex 

Adrenal medulla 

Islets, pancreatic 

Parathyroid gland 

Pituitary gland 

Pars distalis, adenoma 

Pars intermedia, adenoma 

Thyroid gland 

Follicular cell, adenoma 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

MMMMMM+ + + + + + + + + + + + + + + + +M+ 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

General Body System 

Tissue NOS 

Alveolar/bronchiolar carcinoma, 

metastatic, lung 

+ 

X 

Genital System 

Clitoral gland 

Duct, adenoma 

Ovary 

Teratoma benign 

Uterus 

Carcinoma 

Hemangiosarcoma 

Polyp stromal 

Cervix, hemangiosarcoma 

X 

X 

X X 
Lesions in Female Mice 281 

TABLE D2 

Individual Animal Tumor Pathology of Female Mice in the 2-Year Inhalation Study of Nickel Oxide: 1.25 mg/m 3 

(continued) 

Number of Days on Study 

7777777777777777777777777 

2222222333333333333333333 

6999999000000001111111122 

Carcass ID Number 

2222223222222232222222322 

8555771466788914456789146 

6138293969329825601802115 

Alimentary System 

Esophagus 

Gallbladder 

Intestine large, colon 

Intestine large, rectum 

Intestine large, cecum 

Intestine small, duodenum 

Intestine small, jejunum 

Intestine small, ileum 

Liver 

Hemangiosarcoma, multiple 

Hemangiosarcoma, metastatic, uterus 

Hepatocellular carcinoma 

Hepatocellular adenoma 

Mesentery 

Pancreas 

Salivary glands 

Stomach, forestomach 

Stomach, glandular 

Tooth 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + +MM+ +M+M+ + + +MM+ + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X X X 

XXX X X 

+ 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ 

Cardiovascular System 

Heart + + + + + + + + + + + + + + + + + + + + + + + + + 

Endocrine System 

Adrenal cortex 

Adrenal medulla 

Islets, pancreatic 

Parathyroid gland 

Pituitary gland 

Pars distalis, adenoma 

Pars intermedia, adenoma 

Thyroid gland 

Follicular cell, adenoma 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + +M+ + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + +M+ + + + + + + + + + +M+ 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X X X X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

General Body System 

Tissue NOS 

Alveolar/bronchiolar carcinoma, 

metastatic, lung 

Genital System 

Clitoral gland 

Duct, adenoma 

Ovary 

Teratoma benign 

Uterus 

Carcinoma 

Hemangiosarcoma 

Polyp stromal 

Cervix, hemangiosarcoma 

+M+ + +M+ + + + + + + + + + + + + + + + +I + 

X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

X 
282 Nickel Oxide, NTP TR 451 

TABLE D2 

Individual Animal Tumor Pathology of Female Mice in the 2-Year Inhalation Study of Nickel Oxide: 1.25 mg/m 3 

(continued) 

Number of Days on Study 

7777777777777777 

3333333333333333 

2222223333333366 

Carcass ID Number 

2222332222333322 

6899014566001178 

7456398723074801 

Total 

Tissues/ 

Tumors 

Alimentary System 

Esophagus + + + + + + + + + + + + + + + + 66 

Gallbladder + + + + + + + + + + + + + + + + 59 

Intestine large, colon + + + + + + + + + + + + + + + + 61 

Intestine large, rectum + M + + M + + + M + + + + + + M 50 

Intestine large, cecum + + + + + + + + + + + + + ÷ + + 60 

Intestine small, duodenum + + + + + + + + + + + + + + + + 60 

Intestine small, jejunum + + + + + + + + + + + + + + + + 59 

Intestine small, ileum + + + + + + + M + + + + + + + + 57 

Liver + + + + + + + + + + + + + + + + 66 

Hemangiosarcoma, multiple 1 

Hemangiosarcoma, metastatic, uterus X 1 

Hepatocellular carcinoma X X 10 

Hepatocellular adenoma X 7 

Mesentery + 2 

Pancreas + + + + + + + + + + + + + + + + 66 

Salivary glands + + + + + + + + + + + + + + + + 66 

Stomach, forestomach + + + + + + + + + + + + + + + + 63 

Stomach, glandular + + + + + + + + + + + + + + + + 63 

Tooth 1 

Cardiovascular System 

Heart + + + + + + + + + + + + + + + + 66 

Endocrine System 

Adrenal cortex + + + + + + + + + + + + + + + + 66 

Adrenal medulla + + + + + + + + + + + + + + + + 65 

Islets, pancreatic + + + + + + + + + + + + + + I + 65 

Parathyroid gland + + + M M + + + + + + + + + + + 55 

Pituitary gland + + + + + + + + + + + + + + + + 66 

Pars distalis, adenoma X X X 9 

Pars intermedia, adenoma X 1 

Thyroid gland + + + ÷ + + + + + + + + + + + + 66 

Follicular cell, adenoma 1 

General Body System 

Tissue NOS 1 

Alveolar/bronchiolar carcinoma, 

metastatic, lung 1 

Genital System 

Clitoral gland + + + M + + + + + + + + + + + + 62 

Duct, adenoma 1 

Ovary + + + + + + + + + + + + + + + + 66 

Teratoma benign 1 

Uterus + + + + + + + + + + + + + + + + 66 

Carcinoma X 1 

Hemangiosarcoma X 2 

Polyp stromal X 4 

Cervix, hemangiosarcoma 1 
Lesions in Female Mice 283 

TABLE D2 

Individual Animal Tumor Pathology of Female Mice in the 2-Year Inhalation Study of Nickel Oxide: 1.25 mg/m 3 

(continued) 

Number of Days on Study 

0123455555666666666666677 

4601616899002445578899912 

6237906337396042763302510 

Carcass ID Number 

3322232222222223222223223 

• 

0299514964858770677980591 

8014974047765514067386476 

Hematopoietic System 

Bone marrow 

Lymph node 

Lymph node, bronchial 

Alveolar/bronchiolar carcinoma, 

metastatic, lung 

Lymph node, mandibular 

Sarcoma, metastatic, skin 

Lymph node, mesenteric 

Lymph node, mediastinal 

Alveolar/bronchiolar carcinoma, 

metastatic 

Alveolar/bronchiolar carcinoma, 

metastatic, lung 

Spleen 

Hemangiosarcoma 

Thymus 

Alveolar/bronchiolar carcinoma, 

metastatic 

Alveolar/bronchiolar carcinoma, 

metastatic, lung 

+ +M + + + + + + + + + + + + + + + + + + + + + + 

++ + 

+MM+ ++ +++ ++++ + + + + + + + + + + + + 

X X 

+M+ + + + +M+ + + + + + +I + + + + + + + + + 

X 

M+ + + + + + + + + +M+ + + + + + + + + + + + + 

MMM+I M++M+ + +I + +MM+ +I +MMM+ 

X 

X 

+ + + + ÷ + + + + + + + + + + + + + + + + + + + + 

X 

+ + + + + + + + + + + + + +M+ + + +I + + + + + 

X 

Integumentary System 

Mammary gland 

Adenoma 

Carcinoma 

Skin 

Hemangiosarcoma 

Melanoma NOS 

Sarcoma 

Pinna, sarcoma 

Subcutaneous tissue, hemangiosarcoma 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

+ + + + + + 

X 

X 

X 

Musculoskeletal System 

Bone 

Alveolar/bronchiolar carcinoma, 

metastatic, lung 

+ + I + + + + + + + + + + + + + + + + + + + + + + 

X 

Nervous System 

Brain 

Spinal cord 
284 Nickel Oxide, NTP TR 451 

TABLE D2 

Individual .Animal Tumor Pathology of Female Mice in the 2-Year Inhalation Study of Nickel Oxide: 1.25 mg/m 3 

(continued) 

Number of Days on Study 

7777777777777777777777777 

2222222333333333333333333 

6999999000000001111111122 

Carcass ID Number 

2222223222222232222222322 

. 

8555771466788914456789146 

6138293969329825601802115 

Hematopoietic System 

Bone marrow 

Lymph node 

Lymph node, bronchial 

Alveolar/bmnchiolar carcinoma, 

metastatic, lung 

Lymph node, mandibular 

Sarcoma, metastatic, skin 

Lymph node, mesenteric 

Lymph node, mediastinal 

Alveolar/bronchiolar carcinoma. 

metastatic 

Alveolar/bronchiolar carcinoma, 

metastatic, lung 

Spleen 

Hemangiosarcoma 

Thymus 

Alveolar/bronchiolar carcinoma, 

metastatic 

Alveolar/bronchiolar carcinoma, 

metastatic, lung 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+MMMM+I +M++MMM+I + + +MMMMM+ 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

+++ ++++++M+M+ +++++++ +M+++ 

Integumentary System 

Mammary gland 

Adenoma 

Carcinoma 

Skin 

Hemangiosarcoma 

Melanoma NOS 

Sarcoma 

Pinna, sarcoma 

Subcutaneous tissue, hemangiosarcoma 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X X 

+ + 

X 

X 

Musculoskeletal System 

Bone 

Alveolar/bronchiolar carcinoma, 

metastatic, lung 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

Nervous System 

Brain 

Spinal cord 
Lesions in Female Mice 285 

TABLE D2 

Individual Animal Tumor Pathology of Female Mice in the 2-Year Inhalation Study of Nickel Oxide: 1.25 mg/m 3 

(continued) 

Number of Days on Study 

7777777777777777 

3333333333333333 

2222223333333366 

Carcass ID Number 

2222332222333322 

6899014566001178 

7456398723074801 

Total 

Tissues/ 

Tumors 

Hematopoietic System 

Bone marrow 

Lymph node 

Lymph nt~.le, bronchial 

Alveolar/bronchiolar carcinoma, 

metastatic, lung 

Lymph node, mandibular 

Sarcoma, metastatic, skin 

Lymph node, mesenteric 

Lymph node, mediastinal 

Alveolar/bronchiolar carcinoma, 

metastatic 

Alveolar/bronchiolar carcinoma, 

metastatic, lung 

Spleen 

Hemangiosarcoma 

Thymus 

Alveolar/bronchiolar carcinoma, 

metastatic. 

Alveolar/bronchiolar carcinoma, 

metastatic, lung 

+ + + + + + + + + + + + + + + + 

+ 

+ + + + + + + +I + + + + + + + 

+ + + + + + + + + + + + + + ~ + 

+ + + + + + M + + + + + + + + + 

+I MMI ÷M++ + +I MMMI 

+ + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + 

65 

9 

63 

2 

63 

1 

63 

28 

1 

66 

2 

61 

Integumentary System 

Mammary gland 

Adenoma 

Carcinoma 

Skin 

Hemangiosarcoma 

Melanoma NOS 

Sarcoma 

Pinna, sarcoma 

Subcutaneous tissue, hemangiosarcoma 

+ + + + + + + + + + + + + + + + 

X 

66 

1 

3 

8 

1 

1 

1 

1 

1 

Musculoskeletal System 

Bone 

Alveolar/bronchiolar carcinoma, 

metastatic, lung 

+ + ÷ + ÷ + + + + + + + + + + + 65 

1 

Nervous System 

Brain 

Spinal cord 

+ + + + + + + + + + + + + + ÷ + 66 

1 
286 Nickel Oxide, NTP TR 451 

TABLE D2 

Individual Animal Tumor Pathology of Female Mice in the 2-Year Inhalation Study of Nickel Oxide: 1.25 mg/m 3 

(continued) 

Number of Days on Study 

0123455555666666666666677 

46016168991) 02445578899912 

6237906337396042763302510 

Carcass ID Number 

3322232222222223222223223 

0299514964858770677980591 

8014974047765514067386476 

Respiratory System 

Larynx 

Lung 

Alveolar/bronchiolar adenoma 

Alveolar/bronchiolar adenoma, multiple 

Alveolar/bronchiolar carcinoma 

Alveolar/bronchiolar carcinoma, multiple 

Hepatocellular carcinoma, metastatic 

Nose 

Trachea 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

X X X X X 

X 

X 

+ + + + + + + + + A + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

Special Senses System 

Ear 

Harderian gland 

Adenoma 

+ 

X 

Urinary System 

Kidney 

Urinary bladder 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

A + + + + + + + +A + + + + + + + + + + + + + +M 

Systemic Lesions 

Multiple organs 

Lymphoma malignant XX X XX 
Lesions in Female Mice 287 

TABLE D2 

Individual Animal Tumor Pathology of Female Mice in the 2-Year Inhalation Study of Nickel Oxide: 1.25 mg/m 3 

(continued) 

Number of Days on Study 

7777777777777777777777777 

2222222333333333333333333 

6999999000000001111111122 

Carcass ID Number 

222222322222223.2222222322 

8555771466788914456789146 

6138293969329825601802115 

Respiratory System 

Larynx 

Lung 

Alveolar/bronchiolar adenoma 

Alveolar/bronchiolar ader~oma, multiple 

Alveolar/bronchiolar carcinoma 

Alveolar/bronchiolar carcinoma, multiple 

Hepatocellular carcinoma, metastatic 

Nose 

Trachea 

+ + + + + + + + + + +I + + + + + + + + + + +I + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

X 

X X X X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

Special Senses System 

Ear 

Harderian gland 

Adenoma 

Urinary System 

Kidney 

Urinary bladder 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ +M+ + + + + + + + + + + + + + + + + + + + + + 

Systemic Lesions 

Multiple organs 

Lymphoma malignant X X X X X X 
288 Nickel Oxide, NTP TR 451 

TABLE D2 

Individual Animal Tumor Pathology of Female Mice in the 2-Year Inhalation Study of Nickel Oxide: 1.25 mg/m 3 

(continued) 

Number of Days on Study 

777777777777.7777 

3333333333333333 

2222223333333366 

Carcass ID Number 

2222332222333322 

6899014566001178 

7456398723074801 

Total 

Tissues/ 

Tumors 

Respiratory System 

Larynx + + + + + + + + + + + + + + I + 63 

Lung + + + + + + + + + + + + + + + + 66 

Alveolar/bronchiolar adenoma 2 

Alveolar/bronchiolar adenoma, multiple X 2 

Alveolar/bronchiolar carcinoma X 10 

AIv¢olar/bronchiolar carcinoma, multiple 1 

Hepatocellular carcinoma, metastatic 1 

Nose + + + + + + + + + + + + + + + + 65 

Trachea + + + + + + + + + + + + + + + + 66 

Special Senses System 

Ear + 1 

Harderian gland 1 

Adenoma 1 

Urinary System 

Kidney + + + + + + + + + + + + + + + + 66 

Urinary bladder + + + + + + + + + + + + + + + + 62 

Systemic Lesions 

Multiple organs + + + + + + + + + + + + + + + + 66 

Lymphoma malignant X 12 
Lesions in Female Mice 289 

TABLE D2 

Individual Animal Tumor Pathology of Female Mice in the 2-Year Inhalation Study of Nickel Oxide: 2.5 mg/m 3 

Number of Days on Study 

000033345555566666666777 

113512253678834567778222 

696851618604700990061999 

Carcass ID Number 

444444444444444444444444 

321502201111151672343012 

730290175436952607394182 

Alimentary System 

Esophagus 

Gallbladder 

Intestine large, colon 

Intestine large, rectum 

Intestine large, cecum 

Intestine small, duodenum 

Intestine small, jejunum 

Intestine small, ileum 

Liver 

Hemangiosarcoma 

Hepatocellular carcinoma 

Hepatocellular adenoma 

Hepatocellular adenoma, multiple 

Mesentery 

Pancreas 

Salivary glands 

Stomach, forestomach 

Stomach, glandular 

Tooth 

+ + + + + + + + + + + + + + + + + + + + + + + + 

MAAA + + +A ++ + + + + +A + + + + + + + + 

A +A A + + +A + + + + + + +A + + + + + + + + 

A +A A + + + + + + + + + + +A + + + + +M+ + 

A +A A + + +A + + + + + + +A + + + +A + + + 

A A A A + + +A + + + + + + +A + + + +A + + + 

A A A A + + +A + + + + + + +A + + + +A + + + 

AAAA + + +A + + + + + + +A + + + +A + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + 

X 

X X X X 

X X X X 

+ 

+ + + + + + + + + + + + + + + A + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + +A + + + + + + + + 

+ + + + + + + + + + + + + + + A + + + + + + + + 

Cardiovascular System 

Heart + + + + + + + + + + + + + + + + + + + + + + + + 

Endocrine System. 

Adrenal cortex 

Adrenal medulla 

Pheochromocytoma benign 

Islets, pancreatic 

Parathyroid gland 

Pituitary gland 

Pars distalis, adenoma 

Pars intermedia, adenoma 

Thyroid gland 

Bilateral~ follicular cell, adenoma 

+ + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + ÷ + A + + + + + + + + 

+ +MMMMMM+ + + + +MM+ + + + + +M+ + 

++ ++++M++ +++++ ++++++ ++ ++ 

X 

+ + + + + + + + + + + + + + + + + + + + + + + + 

General Body System 

Tissue NOS 

Fat, hemangiosarcoma 

Genital System 

Clitoral gland 

Ovary 

Cystadenoma 

Granulosa-theca tumor benign 

Uterus 

Hemangioma 

Hemangiosarcoma 

Sarcoma stromal 

+++ +++ +I + +M++++++++ + ++ + + 

++ + +++ +++ ++++++M+MM+ ++ + + 

+ + + + + + + + + + + + + + +A + + + + + + + + 

X 

X 
290 Nickel Oxide, NTP TR 451 

TABLE D2 

Individual Animal Tumor Pathology of Female Mice in the 2-Year Inhalation Study of Nickel 

(continued) 

Oxide: 2.5 mg/m 3 

Number of Days on Study 

7777777777777777777777777 

2222222233333333333333333 

9999999900000001111122222 

Carcass ID Number 

4444444444444444444444444 

3344456824445570455501346 

0212681060370922436757888 

Alimentary System 

Esophagus 

Gallbladder 

Intestine large, colon 

Intestine large, rectum 

Intestine large, cecum 

Intestine small, duodenum 

Intestine small, jejunum 

Intestine small, ileum 

Liver 

Hemangiosarcoma 

Hepatocellular carcinoma 

Hepatocellular adenoma 

Hepatocellular adenoma, multiple 

Mesentery 

Pancreas 

Salivary glands 

Stomach, forestomach 

Stomach, glandular 

Tooth 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + +.+ + + + + + + + + 

+M+ + + +MM+ + + +MMM+ +MM+ + + +M+ 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X X X 

X X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ 

Cardiovascular System 

Heart + + + + + + + + + + + + + + + + + + + + + + + + + 

Endocrine System 

Adrenal cortex 

Adrenal medulla 

Pheochromocytoma benign 

Islets, pancreatic 

Parathyroid gland 

Pituitary gland 

Pars distalis, adenoma 

Pars intermedia, adenoma 

.Thyroid gland 

Bilateral, follicular cell, adenoma 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

+ + + + + ~ + + + + + + + + + + + + + + + + + + + 

+M+ + +M+ + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + +M + + + + + + + + 

X X X 

X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

General Body System 

Tissue NOS 

Fat, hemangiosarcoma 

Genital System 

Clitoral gland 

Ovary 

Cystadenoma 

Granulosa-theca tumor benign 

Uterus 

Hemangioma 

Hemangiosarcoma 

Sarcoma stromal 

+ + + + + + + + + + + + + + + + + +MM+ + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X X X 

X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 
Lesions in Female Mice 291 

TABLE D2 

Individual Animal Tumor Pathology of Female Mice in the 2-Year Inhalation Study of Nickel Oxide: 2.5 mg/m J 

(continued) 

Number of Days on Study 

77777777777777 

33333333333333 

33333333366666 

Carcass ID Number 

44444444444444 

00223367702266 

38891593844503 

Total 

Tissues/ 

Tumors 

Alimentary System 

Esophagus + + + + + + + + + + + + + + 63 

Gallbladder + + + + + + + + + + + + + + 57 

Intestine large, colon + + + + + + + + + + + + + + 58 

Intestine large, rectum + + M + M + + M M + M M + + 43 

Intestine large, cecum + + + + + + + + + + + + + + 57 

Intestine small, duodenum + + + + + + + + + + + + + + 56 

Intestine small, jejunum + + + + + + + + + + + + + + 56 

Intestine small, ileum + + + + + + + + + + + + + + 56 

Liver + + + + + + + + + + + + + + 63 

Hemangiosarcoma 1 

Hepatocellularcarcinoma X 8 

Hepatocellular adenoma X X 8 

Hepatocellular adenoma, multiple X 1 

Mesentery 1 

Pancreas + + + + + + + + + + + + + + 62 

Salivary glands + + + + + + + + + + + + + + 63 

Stomach, forestomach + + + + + + + + + + + + + + 62 

Stomach, glandular + + + + + + + + + + + + + + 62 

Tooth 1 

Cardiovascular System 

Heart + + + + + + + + + + + + + + 63 

Endocrine System 

Adrenal cortex + + + + + + + + + + + + + + 63 

Adrenalmedull~ + + + + + + + + + + + + + + ' 63 

Pheochromocytoma benign 1 

Islets, pancreatic + + + + + + + + + + + + + + 62 

Parathyroid gland + + M + + M + + + M M + + + 48 

Pituitary gland + + + + + + + + + + + + + + 61 

Pars distalis, adenoma X X X X 8 

Pars intermedia, adenoma 1 

Thyroid gland + + + + + + + + + + + + + + 63 

Bilateral, follicular cell, adenoma X 1 

General Body System 

Tissue NOS + 1 

Fat, hemangiosarcoma • X 1 

Genital System 

Clitoral gland + + I M + + + + + + + + + + 57 

Ovary + + + + + + + + + + + + + + 60 

Cystadenoma 3 

Granulosa-theca tumor benign 1 

Uterus + + + + + + + + + + + + + + 62 

Hemangioma 1 

Hemangiosarcoma 1 

Sarcoma stromal X 1 
292 Nickel Oxide, NTP TR 451 

TABt,~ D2 

Individual Animal Tumor Pathology of Female Mice in the 2-Year Inhalation Study of Nickel Oxide: 2.5 mg/m 3 

(continued) 

Number of Days on Study 

000033345555566666666777 

113512253678834567778222 

696851618604700990061999 

Carcass ID Number 

444444444444444444444444 

321502201111151672343012 

730290175436952607394182 

Hematopoietic System 

Bone marrow 

Hemangiosarcoma 

Hemangiosarcoma, metastatic, spleen 

Lymph node 

Axillary, hemangiosarcoma 

Lymph node, bronchial 

Lymph node, mandibular 

Lymph node, mesenteric 

Hemangiosarcoma, metastatic, liver 

Lymph node, mediastinal 

Spleen 

Hemangiosarcoma 

Thymus 

++++M+++++++++++ 

X 

X 

+ 

++++++++ 

+ + + + 

M+MM++ + +++++++++ ++ + ++ +I + 

+ + + + + +M+ + + + +M+ +AM+ + + + + + + 

M+MM+ +M+ + + +M+ + +A + + + + + + + + 

X 

MMMMM++ + +++MI ++ +M+M+ + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + 

X X 

+ + + + + + + + + + + + + + + + + +M+ + + + + 

Integumentary System 

Mammary gland + + + + + + + + + + + + + + + + + + + + + + + + 

Skin + + + + 

Sarcoma 

Sebaceous gland, adenoma X 

Musculoskeletal System 

Bone + + + + + + + + + + + + + + + + + + + + + + + + 

Nervous System 

Brain + + + + + + + + + + + + + + + + + + + + + + + + 

Respiratory System 

Larynx 

Lung 

Alveolar/bronchiolar adenoma 

Alveolar/bronchiolar carcinoma 

Hepatocellular carcinoma, metastatic 

Nose 

Trachea 

+ + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + 

X XX X 

X 

X 

+ +A + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + 

Special Senses System 

Ear 

Fibrosarcoma 

Harderian gland 

Adenoma 

+ 

X 

+ 

X 

Urinary System 

Kidney 

Urinary bladder 

+ + + + + + + + + + + + + + + + + + + + + + + + 

M+ + + +++++ + ++ ++ +A + + + ++ + + + 

Systemic Lesions 

Multiple organs 

Lymphoma malignant XX X X X 
Lesions in Female Mice 293 

TABLE D2 

Individual Animal Tumor Pathology of Female Mice in the 2-Year Inhalation Study of Nickel Oxide: 2.5 mg/m ~ 

(continued) 

Number of Days on Study 

7777777777777777777777777 

2222222233333333333333333 

9999999900000001111122222 

Carcass ID Number 

4444444444444444444444444 

3344456824445570455501346 

0212681060370922436757888 

Hematopoietic System 

Bone marrow 

Hemangiosarcoma 

Hemangiosarcoma, metastatic, spleen 

Lymph node 

Axillary, hemangiosar¢oma 

Lymph node, bronchial 

Lymph node, mandibular 

Lymph node, mesenteric 

Hemangiosarcoma, metastatic, liver 

Lymph node, mediastinal 

Spleen 

Hemangiosarcoma 

Thymus 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ ++ + 

X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+MM+M+ +MMMMMMM+MM+MM+MMI I 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X X 

+ + + + + + + + + + + + + + + + + I + + + + + + + 

Integumentary System 

Mammary gland 

Skin 

Sarcoma 

Sebaceous gMnd, adenoma 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

Musculoskeletal System 

Bone + + + + + + + + + + + + + + + + + + + + + + + + + 

Nervous System 

Brain + + + + + + + + + + + + + + + + + + + + + + + + + 

Respiratory System 

Larynx 

Lung 

Alveolar/bronchiolar adenoma 

Alveolar/bronchiolar carcinoma 

Hepatocellular carcinoma, metastatic 

Nose 

Trachea 

+ +++ +++ + + ++ + + + +M++++ ++ + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X X X X X 

X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

Special Senses System 

Ear 

Fibrosarcoma 

Harderian gland 

Adenoma 

+ 

X 

Urinary System 

Kidney 

Urinary bladder 

+ + + + + + + + + + + + + + + + + + + + + + + ÷ + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

Systemic Lesions 

Multiple organs 

Lymphoma malignant X X 
294 Nickel Oxide, NTP TR 451 

TABLE D2 

Individual Animal Tumor Pathology of Female Mice in the 2-Year Inhalation Study of Nickel Oxide: 

(continued) 

2.5 mg/m 3 

Number of Days on Study 

77777777777777 

33333333333333 

33333333366666 

Carcass ID Number 

44444444444444 Total 

00223367702266 Tissues/ 

38891593844503 Tumors 

Hematopoietic System 

Bone marrow + + + + + + + + + + + + + + 62 

Hemangiosarcoma 1 

Hemangiosarcoma, metastatic, spleen 1 

Lymph node + 10 

Axillary, hemangiosarcoma 1 

Lymph node, bronchial + + + + + + + + + + + + + + 59 

Lymph node, mandibular + + + + + + + + + + + + + + 59 

Lymph node, mesenteric + M M + + + + + M + + + + + 54 

Hemangiosarcoma, metastatic, liver 1 

Lymph node, mediastinal + + + + + + + + M I + + M + 33 

Spleen + + + + + + + + + + + + + + 63 

Hemangiosarcoma X 5 

Thymus + + + + + + + M + + + + + + 60 

Integumentary System 

• 

Mammary gland + + + + + + + + + + + + + + 63 

Skin + + 6 

Sarcoma X 1 

Sebaceous gland, adenoma 1 

Musculoskele~! System 

Bone + + + + + + + + + + + + + + 63 

NervousSystem 

B~in + + + + + + + + + + + + + + 63 

Respiratory System 

Larynx + + + + + + + + + + + + + + 62 

Lung + + + + + + + + + + + + + + 63 

Alveolar/bronchiolar adenoma X 10 

Alveolar/bronchiolar carcinoma X X 4 

Hepatocellular carcinoma, metastatic 1 

Nose + + +-+ + + + + + + + + + + 62 

Trachea + + ÷ +:+ + + + + + + + + + 63 

Special Senses System 

Ear 1 

Fibrosarcoma 1 

Harderian gland 2 

Adenoma 2 

Urinary System 

Kidney + + + + + + + + + + + + + + 63 

Urinary bladder • M + + + + + + + + + + + + + 60 

Systemic Lesions 

Multiple organs + + + + + + + + + + + + + + 63 

Lymphoma malignant X X 9 
Lesions in Female Mice 295 

TABLE D2 

Individual Animal Tumor Pathology of Female Mice in the 2-Year Inhalation Study of Nickel Oxide: 5 mg/m 3 

Number of Days on Study 

012444455556666666666667 

749269913890144457778991 

013695803452904480354693 

Carcass ID Number 

565556666655665566566655 

908893213266139920902167 

95545601268361131246 ~ 792 

Alimentary System 

Esophagus 

Squamous cell carcinoma 

Gallbladder 

Sarcoma, metastatic, mesentery 

Intestine large, colon 

Hepatocholangiocarcinoma, metastatic, liver 

Intestine large, rectum 

Intestine large, cecum 

Leiomyosarcoma 

Sarcoma, metastatic, mesentery 

Intestine small,-duodenum 

Hepatocholangiocarcinoma, metastatic, liver 

Intestine small, jejunum 

Intestine small, ileum 

Liver 

Hemangiosarcoma 

Hepatocellular carcinoma 

Hepatocellular adenoma 

Hepatocholangiocarcinoma 

Histiocytic sarcoma 

Sarcoma, metastatic, nlesentery 

Mesentery 

Hepatocholangiocarcinoma, metastatic, liver 

Sarcoma 

Pancreas 

Hepatocholangiocarcinoma, metastatic, liver 

Sarcoma, metastatic, mesentery 

Salivary glands 

Stomach, fnrestomach 

Sarcoma, metastatic, mese~ltery 

Squamous cell papilloma 

Stomach, glandular 

Hepatocholangiocarcinoma, metastatic, liver 

Sarcoma, metastatic, mesentery 

Tooth 

Odontoma 

+++ ++ 4++A + +++ + + + + + +++ + + + 

+A + + +MAAA A + + + + + + + + + + + + +A 

X 

+ A + + +A A A A A + + + + + + + + + + + + + + 

X 

+A + + +AAAAA +M+ +M+ + + + + + + + + 

+A + + +AAAAA + + + + + + + + + + + + +A 

X 

X 

+A + + +AAAAA ++ + + + + + + + + + + +A 

X 

+A + + +A AAA A + + + + + + + + + + + + +A 

+A + + +AAAAA + + +A + + + +M+ + + +A 

+ + + + + + + +A + + + + + + + + + + + + + + + 

X 

X X 

X 

X X 

X 

+ + + 

X 

X 

+ + + + + + +A A + + + + + + + + + + + + + + + 

X 

X 

+ + + + + + + + A + + + + + + + + + + + + + + + 

+A + + +A +AA + + + + + + + + + + + + + + + 

X 

X 

+A + + +A +AA + + + + + + + + + + + + + + + 

X 

X 

+ 

Cardiovascular System 

Heart 

Hepatocholangincarcinoma, metastatic, liver 

+ + + + + + + + + + + + + + + + + + + + + + + + 

X 

Endocrine System 

Adrenal cortex 

Adenoma 

Hepatocholangiocarcinoma, metastatic, liver 

Adrenal medulla 

Islets, pancreatic 

Parathyroid gland 

+ + + + + + + +A + + + + + + + + +M+ + + + + 

X 

+ + + + + + + +A + + + + + + + + +M+ + + + + 

+ + + + + + +AA + + + + + + + + + + + + + + + 

M+M+ + + + + + + + + + +M+M+ + + + + + + 
296 Nickel Oxide, NTP TR 451 

TABLE D2 

Individual Animal Tumor Pathology of Female Mice in the 2-Year Inhalation Study of Nickel Oxide: 5 mg/m 3 

(continued) 

Number of Days on Study 

7777777777777777777777777 

2222222233333333333333333 

0699999900000011111111111 

Carcass ID Number 

5655666655566655555555666 

7169133468822266777789001 

8042208028927867034936399 

Alimentary System 

Esophagus 

Squamous cell carcinoma 

Gallbladder 

Sarcoma, metastatic, mesentery 

Intestine large, colon 

Hepatocholangiocarcinoma, metastatic, liver 

Intestine large, rectum 

Intestine large, cecum 

Leiomyosarcoma 

Sarcoma, metastatic, mesentery 

Intestine small, duodenum 

Hepatocholangiocarcinoma, metastatic, liver 

Intestine small, jejunum 

Intestine small, ileum 

Liver 

Hemangiosarcoma 

Hepatocellular carcinoma 

Hepatucellular adenoma 

Hepatocholangiocarcinoma 

Histiocytic sarcoma 

Sarcoma, metastatic, mesentery 

Mesentery 

Hepatocholangiocarcinoma, metastatic, liver 

Sarcoma 

Pancreas 

Hepatocholangiocarcinoma, metastatic, liver 

Sarcoma, metastatic, mesentery 

Salivary glands 

Stomach, forestomach 

Sarcoma, metastatic, mesentery 

Squamous cell papilloma 

Stomach, glandular 

Hepatocholangiocarcinoma, metastatic, liver 

Sarcoma, metastatic, mesentery 

Tooth 

Odontoma 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

A +++++++++++++++++ ++ ++ ++ + 

A + + + + + + + + + + + + + + + + + + + + + • + + 

A + + +M+ +MMMM+ + + + + + + +M+ +M+ + 

A ++++++++++ + + + + +++ ++++ + + + 

A + + + + + + + + + + + + + + + + + + + + + + + + 

A + + + + + + + + + + + + + + + + + + + + + + + + 

A + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X XX X X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

.+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ 

X 

Cardiovascular System 

Heart 

Hepatocholangiocarcinoma, metastatic, liver 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

Endocrine System 

Adrenal cortex 

Adenoma 

Hepatocholangiocarcinoma, metastatic, liver 

Adrenal medulla 

Islets, pancreatic 

Parathyroid gland +M+ + + + +M+ +M+ + + + + + +I + + +M+ + 
Lesions in Female Mice 297 

TABLE D2 

Individual Animal Tumor Pathology of Female Mice in the 2-Year Inhalation Study of Nickel Oxide: 

(continued) 

5 mg/m 3 

Number of Days on Study 

777777777777777 

333333333333333 

222222233333666 

Carcass ID Number 

555666655566556 

678013368923883 

572034916057175 

Total 

Tissues/ 

Tumors 

Alimentary System 

Esophagus 

Squamous cell carcinoma 

Gallbladder 

Sarcoma, metastatic, mesentery 

Intestine large, colon 

Hepatocholangiocarcinoma, metastatic, liver 

Intestine large, rectum 

Intestine large, cecum 

Leiomyosarcoma 

Sarcoma, metastatic, mesentery 

Intestine small, duodenum 

Hepatocholangiocarcinoma, metastatic, liver 

Intestine small, jejunum 

Intestine small, ileum 

Liver 

Hemangiosarcoma 

Hepatocellular carcinoma 

Hepatocellular adenoma 

Hepatocho!angiocarcinoma 

Histiocytic sarcoma 

Sarcoma, metastatic, mesentery 

Mesentery 

Hepatocholangiocarcinoma, metastatic, liver 

Sarcoma 

Pancreas 

Hepatochola~giocarcinoma, metastatic, liver 

Sarcoma, metastatic, mesentery 

Salivary glands 

Stomach, forestomach 

Sarcoma, metastatic, mesentery 

Squamous cell papilloma 

Stomach, glandular 

Hepatocholangiocarcinoma, metastatic, liver 

Sarcoma, metastatic, mesentery 

Tooth 

Odontoma 

+ + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + 

+ + + +M+M+MM+ + + +M 

+ + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + 

X X 

+ + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + 

63 

1 

56 

1 

57 

1 

43 

56 

1 

1 

56 

1 

56 

54 

63 

1 

4 

5 

1 

2 

1 

3 

1 

1 

62 

1 

1 

63 

60 

1 

1 

60 

1 

1 

2 

1 

Cardiovascular System 

Heart 

Hepatocholangiocarcinoma, metastatic, liver 

+ + + + + + + + + + + + + + + 64 

1 

Endocrine System 

Adrenal cortex 

Adenoma 

Hepatocholangiocarcinoma, metastatic, liver 

Adrenal medulla 

Islets, pancreatic 

Parathyroid gland 

+ + + + + + + + + + + + + + + 

X 

+ + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + 

62 

1 

1 

62 

62 

55 
298 Nickel Oxide, NTP TR 451 

TABLE D2 

Individual Animal Tumor Pathology of Female Mice in the 2-Year Inhalation Study of Nickel Oxide: 5 mg/m ~ 

(continued) 

Number of Days on Study 

012444455556666666666667 

749269913890144457778991 

013695803452904480354693 

Carcass ID Number 

565556666655665566566655 

908893213266139920902167 

955456012683611312464792 

Endocrine System (continued) 

Pituitary gland 

Pars distalis, adenoma 

Pars distalis, carcinoma 

Pars intermedia, adenoma 

Thyroid gland 

Follicular cell, adenoma 

+ + + + + + + +A + + + + + + + +M+ + + + + + 

X X 

X 

+ + + + + + + + + + + + + + + + + + + + + + + + 

X 

General Body System 

Tissue NOS 

Hemangiosarcoma, metastatic 

+ 

X 

Genital System 

Clitoral gland 

Ovary 

Sarcoma, metastatic, mesentery 

Teratoma malignant 

Uterus 

Hemangiosarcoma 

Polyp stromal 

Sarcoma, metastatic, mesentery 

Teratoma malignant, metastatic 

MMM+++ + +A ++ + +M+++++ ++ ++ + 

+ + + + + + + +A + + + + + + + + + + + + + + + 

X 

X 

+ + + + + + + +A + + + + + + + + + + + + + + + 

X 

X 

Hematopoietic System 

Bone marrow 

Hemangiosarcoma, metastatic 

Lymph node 

Pancreatic, histiocytic sarcoma 

Pancreatic, sarcoma, metastatic, mesentery 

Renal, sarcoma, metastatic, mesentery 

Lymph node, bronchial 

Histiocytic sarcoma 

Sarcoma, metastatic, mesentery 

Lymph node, mandibular 

Lymph node, mesenteric 

Hemangioma 

Hepatocholangiocarcinoma, metastatic, liver 

Sarcoma, metastatic, mesentery 

Lymph node, mediastinal 

Hepatocholangiocarcinoma, metastatic, liver 

Histiocytic sarcoma 

Sarcoma, metastatic, mesentery 

Spleen 

Hemangiosarcoma 

Hepatocholangiocarcinoma, metastatic, liver 

Histiocytic sarcoma 

Sarcoma, metastatic, mesentery 

Thymus 

Hepatocholangiocarcinoma, metastatic, liver 

Histiocytic sarcoma 

Sarcoma, metastatic, mesentery 

+ + + + + + + + A + + + + + + + + + + + + + + + 

X 

+ +++ + 

X 

X 

X 

+ +++++++ + + + +M+ + +++ ++ + + + + 

X X 

X 

+ + + +~+M+ +AM+ + + +M+ + + +M+ + + + 

+M+ + +M+MMM+ + + + + + +M+M+M+ + 

X 

X 

MMM+ + + +MMM+ + +M+ + + + +MM+ +M 

X 

X 

X 

+ + + + + + + +A + + + + + + + + + + + + + + + 

X X 

X 

X X 

X 

+ + + + + + + +MM+ + + + + + + + + + + + +M 

X 

X 

X 
Lesions in Female Mice 299 

TABLE D2 

Individual Animal Tumor Pathology of Female Mice in the 2-Year Inhalation Study of Nickel Oxide: 5 mg/m 3 

(continued) 

Number of Days on Study 

7777777777777777777777777 

2222222233333333333333333 

0699999900000011111111111 

Carcass ID Number 

565566665556665 ~ 555555666 

7169133468822266777789001 

8042208028927867034936399 

Endocrine System (continued) 

Pituitary gland 

Pars distalis, adenoma 

Pars distalis, carcinoma 

Pars intermedia, adenoma 

Thyroid gland 

Follicular cell, adenoma 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

General Body System 

Tissue NOS 

Hemangiosarcoma, metastatic 

Genital System 

Clitoral gland 

Ovary 

Sarcoma, metastatic, mesentery 

Teratoma malignant 

Uterus 

Hemangiosarcoma 

Polyp stromal 

Sarcoma, metastatic, mesentery 

Teratoma malignant, metastatic 

+ ++++M+ ++M++M++++++M+ + + ++ 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

Hematopoietic System 

Bone marrow 

Hemangiosarcoma, metastatic 

Lymph node 

Pancreatic, histiocytic sarcoma 

Pancreatic, sarcoma, metastatic, mesentery 

Renal, sarcoma, metastatic, mesentery 

Lymph node, bronchial 

Histiocytic sarcoma 

Sarcoma, metastatic, mesentery 

Lymph node, mandibular 

Lymph node, mesenteric 

Hemangioma 

Hepatocholangiocarcinoma, metastatic, liver 

Sarcoma, metastatic, mesentery 

Lymph node, mediastinal 

Hepatocholangiocarcinoma, metastatic, liver 

Histiocytic sarcoma 

Sarcoma, metastatic, mesentery 

Spleen 

Hemangiosarcoma 

Hepatocholangiocarcinoma, metastatic, liver 

Histiocytic sarcoma 

Sarcoma, metastatic, mesentery 

Thymus 

Hepatocholangiocarcinoma, metastatic, liver 

Histiocytic sarcoma 

Sarcoma, metastatic, mesentery 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ 

+ +++ ++ + +++ + + + + + ++ + + + +M+ ++ 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + M + + + + + 

X 

+M+M+M+MI +I MMM+I M+MMI +MI M 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

++ + ++ +++ + ++++ + + ++ +M+I M+ ÷+ 

Lesions in Female Mice 301 

TABLE D2 

Individual Animal Tumor Pathology of Female Mice in the 2oYear Inhalation Study of Nickel Oxide: 5 mg/m 3 

(continued) 

Number of Days on Study 

012444455556666666666667 

749269913890144457778991 

013695803452904480354693 

Carcass ID Number 

565556666655665566566655 

908893213266139920902167 

955456012683611312464792 

Integumentary System 

Mammary gland 

Carcinoma 

Skin 

Sarcoma 

Squamous cell papilloma 

+ + + + + + + +A + + + + + + + + + + + + + + + 

~" X 

+ + ++ + + + 

Musculoskeletal System 

Bone 

Skeletal muscle 

Hepatocholangiocarcinoma, metastatic, liver 

Sarcoma, metastatic, mesentery 

+ + + + + + + + + + + +I + + + + + + + + + + + 

+ + 

X 

X 

Nervous System 

Brain 

Hypothalamus, carcinoma, metastatic 

Pons, carcinoma, metastatic 

+ + + + + + + + + + + + + + + + + + + + + + + + 

X 

X 

Respiratory System 

Larynx 

Lung 

Alveolar/bronchiolar adenoma 

Alveolar/bronchiolar carcinoma 

Hepatocellular carcinoma, metastatic 

Hepatocholangiocarcinoma, metastatic, liver 

Histiocytic sarcoma 

Sarcoma, metastatic, mesentery 

Teratoma malignant, metastatic 

Nose 

Trachea 

+ + + + + + + + A + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + 

X 

X X X 

X 

X X 

X 

++ + ++A ++A ++ + + + + + + + + + + + + + 

+ + ++++++A ++ + ++++++ + + + + + + 

Special Senses System 

Ear 

Eye 

Harderian gland 

Adenoma 

Urinary System 

Kidney 

Hepatocholangiocarcinoma, metastatic, liver 

Teratoma malignant, me.static 

Urethra 

Urinary bladder 

Sarcoma, metastatic, mesentery 

+ + + + + + + + A + + + + + + + + + + + + + + + 

X 

X 

+ 

+A + + +A +AAA + + + + + + + + + + + + + + 

X 

Systemic Lesions 

Multiple organs 

Histiocytic sarcoma 

Lymphoma malignant 

X X 

X X 
302 Nickel Oxide, NTP TR 451 

TABLE D2 

Individual Animal Tumor Pathology of Female Mice in the 2-Year Inhalation Study of Nickel Oxide: 5 mg/m 3 

(continued) 

Number of Days on Study 

7777777777777777777777777 

2222222233333333333333333 

0699999900000011111111111 

Carcass ID Number 

5655666655566655555555666 

7169133468822266777789001 

8042208028927867034936399 

Integumentary System 

Mammary gland 

Carcinoma 

Skin 

Sarcoma 

Squamous cell papilloma 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X X 

+ + 

X 

Musculoskeletal System 

Bone 

Skeletal muscle 

Hepatocholangiocarcinoma, metastatic, liver 

Sarcoma, metastatic, mesentery 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ 

Nervous System 

Brain 

Hypothalamus, carcinoma, metastatic 

Pons, carcinoma, metastatic 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

Respiratory System 

Larynx 

Lung 

Alveolar/bronchiolar adenoma 

Alveolar/bronchiolar carcinoma 

Hepatocellular carcinoma, metastatic 

Hepatocholangiocarcinoma, metastatic, liver 

Histiocytic sarcoma 

Sarcoma, metastatic, mesentery 

Teratoma malignant, metastatic 

Nose 

Trachea 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

÷ + + + + + + + + + + + + + + + + + + + + + + + + 

X X 

X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + ++ + + + + + + + + + + + + + + + + + + 

Special Senses System 

Ear 

Eye 

Harderian gland 

Adenoma 

+ 

+ + 

X X 

+ 

Urinary System 

Kidney 

Hepatocholangiocarcinoma, metastatic, liver 

Teratoma malignant, metastatic 

Urethra 

Urinary bladder 

Sarcoma, metastatic, mesentery 

+ + + ÷ + + + + ÷ + + + + + + ÷ + + + + + + + + + 

+ + ++++ + ++++++ +M+ + ++ ++ ++ + + 

Systemic Lesions 

Multiple organs 

Histiocytic sarcoma 

Lymphoma malignant X X X 
Lesions in Female Mice 303 

TABLE D2 

Individual Animal Tumor Pathology of Female Mice in the 2-Year Inhalation Study of Nickel Oxide: 5 mg/m 3 

(continued) 

Number of Days on Study 

777777777777777 

333333333333333 

222222233333666 

Carcass ID Number 

555666655566556 

678013368923883 

572034916057175 

Total 

Tissues/ 

Tumors 

Integumentary System 

Mammary gland 

Carcinoma 

Skin 

Sarcoma 

Squamous cell papilloma 

+ + + + + + + + + + + + + + + 

+++ 

X 

63 

3 

12 

1 

1 

Musculoskeletal System 

Bone 

Skeletal muscle 

Hepatochola.ngiocarcinoma, metastatic, liver 

Sarcoma, metastatic, mesentery 

+ + + + + + + + + + + + + + + 63 

3 

1 

I 

Nervous System 

Brain 

Hypothalamus, carcinoma, metastatic 

Pons, carcinoma, metastatic 

+ + + + + + + + + + + + + + + 64 

1 

1 

Respiratory System 

Larynx 

Lung 

Alveolar/bronchiolar adenoma 

Alveolar/bronchiolar carcinoma 

Hepatocellular carcinoma, metastatic 

Hepatocholangiocarcinoma, metastatic, liver 

Histiocytic sarcoma 

Sarcoma, metastatic, mesentery 

Teratoma malignant, metastatic 

Nose 

Trachea 

+ + + + + + + + + + + + + + + 

÷ + + + + + + ÷ + + + ÷ + + + 

X 

+ + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + 

63 

64 

3 

5 

1 

1 

2 

1 

1 

62 

63 

Special Senses System 

Ear 

Eye 

Harderian gland 

Adenoma 

+ 

X 

Urinary System 

Kidney 

Hepatocholangiocarcinoma, metastatic, liver 

Teratoma malignant, metastatic 

Urethm 

Urinary bladder 

Sarcoma, metastatic, mesentery 

+ + + + + + + + + + + + + + + 

+ + + + + + ÷ + + ÷ + ÷ ÷ ÷ 

63 

1 

1 

1 

57 

1 

Systemic Lesions 

Multiple organs 

Histiocytic sarcoma 

Lymphoma malignant 

+ + + + + + + + + + + + + + + 

X X 

64 

2 

7 
304 Nickel Oxide, NTP TR 451 

TABLE D3 

Statistical Analysis of Primary Neoplasms in Female Mice in the 2-Year Inhalation Study of Nickel Oxide 

0 mg/m 3 1.25 mg/m 3 2.5 mg/rn 3 5 mg/m 3 

Adrenal Medulla: Benign or Malignant Pheochromocytoma 

Overall rate a 3/62 (5%) 

Adjusted rate b 6.5 % 

Terminal rate c 1/41 (2%) 

First incidence (days) 599 

Life table test d P=0.094N 

Logistic regression test d P=0.089N 

Cochran-Armita~e test d P=0.090N 

Fisher exact test ~ 

Harderian Gland: Adenoma 

Overall rate 0/64 (0%) 

Adjusted rate 0.0% 

Terminal rate 0/41 (0%) 

First incidence (days) -- 

Life table test P=0.058 

Logistic regression test P=0.063 

Cochran-Armitage test P=0.061 

Fisher exact test 

Liver: Hepatocellular Adenoma 

Overall rate 6/64 (9%) 

Adjusted rate 14.6% 

Terminal rate 6/41 (15%) 

First incidence (days) 729 (T) 

Life table test P=0.479N 

Logistic regression test P=0.448N 

Cochran-Armitage test P=0.455N 

Fisher exact test 

Liver: Hepatocellular Carcinoma 

Overall rate 8/64 (13 %) 

Adjusted rate 18.1% 

Terminal rate 6/41 (15%) 

First incidence (days) 586 

Life table test P=0.126N 

Logistic regression test P =0.103N 

Cochran-Armitage test P = 0.115N 

Fisher exact test 

Liver: Hepatocellular Adenoma or Carcinoma 

Overall rate 14/64 (22%) 

Adjusted rate 32.2% 

Terminal rate 12/41 (29%) 

First incidence (days) 586 

Life table test P=0.172N 

Logistic regression test P = 0.122N 

Cochran-Armitage test P=0.149N 

Fisher exact test 

0/65 (0%) 1/63 (2%) 0/62 (0%) 

0.0% 2.4% 0.0% 

0/39 (0%) 1/42 (2%) 0/38 (0%) 

__e 729 (T) -- 

P=0.121N P=0.310N P=0.128N 

P=0.110N P=0.301N P=0.118N 

P=0.113N P=0.303N P=0.122N 

1/66 (2%) 2/63 (3%) 3/64 (5%) 

1.8% 4.4% 7.9% 

0/40 (0%) 1/42 (2%) 3/38 (8%) 

609 640 729 (T) 

P=0.519 P=0.247 P=0.108 

P=0.496 P=0.239 P=0.108 

P=0.508 P=0.244 P=0.122 

7/66 (11%) 9/63 (14%) 5/63 (8%) 

17.0% 19.7% 12.5% 

6/40 (15%) 6/42 (14%) 3/38 (8%) 

720 640 720 

P=0.481 P=0.307 P=0.554N 

P=0.485 P=0.288 P=0.542N 

P=0.524 P=0.281 P=0.511N 

10/66 (15%) 8/63 (13%) 4/63 (6%) 

21.0% 16.3% 9.2% 

5/40 (13%) 4/42 (10%) 2/38 (5%) 

469 451 644 

P=0.409 P=0.591N P=0.208N 

P=0.475 P=0.604N P=0.164N 

P=0.428 P=0.592 P=0.190N 

16/66 (24%) 17/63 (27%) 9/63 (14%) 

33.9% 34.0% 20.9% 

10/40 (25%) 10/42 (24%) 5/38 (13%) 

469 451 644 

P=0.413 P=0.365 P=0.227N 

P=0.525 P=0.345 P=0.159N 

P=0.456 P=0.322 P=0.190N 
Lesions in Female Mice 305 

TABLE D3 

Statistical Analysis of Primary Neoplasms in Female Mice in the 2-Year Inhalation Study of Nickel Oxide (continued) 

0 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 5 mg/m 3 

Lung: Alveolar/bronchiolar Adenoma 

Overall rate 2/64 (3%) 

Adjusted rate 4.7% 

Terminal rate 1/41 (2%) 

First incidence (days) 728 

Life table test P=0.359 

Logistic regression test P=0.394 

Cochran-Armitage test P=0.379 

Fisher exact test 

Lung: Alveolar/bronchiolar Carcinoma 

Overall rate 4•64 (6%) 

Adjusted rate 9.4% 

Terminal rate 3/41 (7%) 

First incidence (days) 694 

Life table test P=0.407N 

Logistic regression test P=0.364N 

Cochran-Armitage test P=0.385N 

Fisher exact test 

4/66 (6%) 10/63 (16%) 3/64 (5%) 

9.3% 21.4% 7.1% 

3/40 (8%) 6/42 (14%) 2/38 (5%) 

652 630 619 

P=0.334 P=0.021 P=0.474 

P=0.369 P=0.017 P=0.517 

P=0.355 P=0.014 P=0.500 

11/66 (17%) 4/63 (6%) 5/64 (8%) 

22.8% 9.0% 10.8% 

5/40 (13%) 3/42 (7%) 2/38 (5%) 

583 630 469 

P =0.057 P=0.633N P=0.483 

P=0.069 P=0.642N P=0.525 

P=0.055 P=0.632 P=0.500 

Lung: Alveolar/bronchiolar Adenoma or Carcinoma 

Overall rate 6/64 (9%) 15/66 (23%) 12/63 (19%) 8/64 (13%) 

Adjusted rate 13.8% 30.8% 25.7% 17.4% 

Terminal rate 4/41 (10%) 8/40 (20%) 8/42 (19%) 4/38 (11%) 

First incidence (days) 694 583 630 469 

Life table test P=0.542 P=0.034 P=0.114 P=0.363 

Logistic regressioh test P=0.487N P=0.043 P=0.099 P=0.422 

Cochran-Armitage test P=0.516N 

Fisher exact test P=0.033 P=0.095 P=0.389 

Mammary Gland: Carcinoma 

Overall rate 2/64 (3%) 

Adjusted rate 4.6% 

Terminal rate 1/41 (2%) 

First incidence (days) 694 

Life table test P=0.478 

Logistic regression test P=0.495 

Cochran-Armitage test P=0.498 

Fisher exact test 

Mammary Gland: Adenoma or Carcinoma 

Overall rate 2/64 (3%) 

Adjusted rate 4.6% 

Terminal rate 1/41 (2%) 

First incidence (days) 694 

Life table test P=0.547 

Logistic regression test P=0.571 

Cochran-Armitage test P=0.569 

Fisher exact test 

3/66 (5%) 0/63 (0%) 3/64 (5%) 

7.5% 0.0% 7.4% 

3/40 (8%) 0/42 (0%) 1/38 (3%) 

729 (T) -- 699 

P=0.489 P=0.245N P=0.472 

P=0.521 P=0.237N P=0.509 

P=0.515 P=0.252N P=0.500 

4/66 (6%) 0/63 (0%) 3/64 (5%) 

9.4% 0.0% 7.4% 

3/40 (8%) 0/42 (0%) 1/38 (3%) 

683 -- 699 

P=0.334 P=0.245N P=0.472 

P=0.370 F=0.237N P=0.509 

P=0.355 P=0.252N P=0.500 
306 Nickel Oxide, NTP TR 451 

TABLE D3 

Statistical Analysis of Primary Neoplasms in Female Mice in the 2-Year Inhalation Study of Nickel Oxide (continued) 

0 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 5 mg/m 3 

Ovary: Cystadenoma 

Overall rate 1/61 (2%) 

Adjusted rate 2.6% 

Terminal rate 1/38 (3 %) 

First incidence (days) 729 (T) 

Life table test P=0.507N 

Logistic regression test P=0.507N 

Cochran-Armitage test P=0.505N 

Fisher exact test 

Pituitary Gland (Pars Distalis): Adenoma 

Overall rate 6/63 (10%) 

Adjusted rate 14.1% 

Terminal rate 5/41 (12%) 

First incidence (days) 694 

Life table test P=0.504N 

Logistic regression test P=0.469N 

Cochran-Armitage test P=0.488N 

Fisher exact test 

Pituitary Gland (Pars Distalis): Adenoma or Carcinoma 

Overall rate 

Adjusted rate 

Terminal rate 

First incidence (days) 

Life table test 

Logistic regression test 

Cochran-Armitage test 

Fisher exact test 

0/66 (0%) 3/60 (5%) 0/63 (0%) 

0.0% 7.1% 0.0% 

0/40 (0%) 3/42 (7%) 0/38 (0%) 

-- 729 (T) -- 

P = 0.490N P = 0.342 P = 0.500N 

P=0.490N P=0.342 P=0.500N 

Spleen: Hemangiosarcoma 

Overall rate 

Adjusted rate 

Terminal rate 

First incidence (days) 

Life table test 

Logistic regression test 

Cochran-Armitage test 

Fisher exact test 

P=0.480N P=0.303 P=0.492N 

Thyroid Gland (Follicular Cell): Adenoma or Carcinoma 

Overall rate 

Adjusted rate 

Terminal rate 

First incidence (days) 

Life table test 

Logistic regression test 

Cochran-Armitage test 

Fisher exact test 

9/66 (14%) 8/61 (13%) 6/62 (10%) 

20,5% 18,8% 14.6% 

7/40 (18%) 7/41 (17%) 4/38 (11%) 

597 640 673 

P=0.287 P=0.387 P=0.574 

P=0.357 P=0.373 P=0.617N 

P=0.326 P=0.364 P=0.607 

7/63 (11%) 9/66 (14%) 8/61 (13%) 7/62 (11%) 

16.5% 20.5% 18.8% 16,5% 

6/41 (15%) 7/40 (18%) 7/41 (17%) 4/38 (11%) 

694 597 640 673 

P=0,534N P=0.388 P=0.498 P =0.564 

P =0.497N P =0.469 P=0.484 P=0.603N 

P=0.517N 

P=0.434 P=0.473 P=0.599 

2/64 (3%) 2/66 (3%) 5/63 (8%) 2/63 (3%) 

4.7%, 4.8% 10.7% 4.4% 

1/41 (2%) 1/40 (3%) 3/42 (7%) 0/38 (0%) 

728 720 538 658 

P=0.496 P=0.679 P=0.230 P=0.678 

P=0.520 P=0.693N P=0.220 P=0.683N 

P=0.504 

P=0.679N P=0.213 P=0.685 

3/62 (5%) 1/66 (2%) 1/63 (2%) 1/64 (2%) 

7.3% 2.3% 2.4% 2,1% 

3/41 (7%) 0/40 (0%) 1/42 (2%) 0/38 (0%) 

729 (T) 711 729 (T) 658 

P=0.258N P=0.313N P=0.297N P=0.323N 

P=0.245N P=0.294N P=0.297N P=0.294N 

P=0.241N 

P=0.286N P=0.303N P=0.298N 
Lesions in Female Mice 307 

TABLE D3 

Statistical Analysis of Primary Neoplasms in Female Mice in the 2-Year Inhalation Study of Nickel Oxide (continued) 

0 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 5 mg/m 3 

Uterus: Stromal Polyp 

Overall rate 2/64 (3%) 

Adjusted rate 4.3 % 

Terminal rate 1/41 (2%) 

First incidence (days) 559 

Life table test P=0.204N 

Logistic regression test P=0.193N 

Cochran-Armitage test P =0.198N 

Fisher exact test 

Uterus: Stromal Polyp or Stromal Sarcoma 

Overall rate 3/64 (5%) 

Adjusted rate 6.7% 

Terminal rate 2/41 (5%) 

First incidence (days) 559 

Life table test P=0.145N 

Logistic regressibn test P=0.132N 

Cochran-Armitage test P=0.138N 

Fisher exact test 

Uterus: Hemangiosarcoma 

Overall rate 0/64 (0%) 

Adjusted rate 0.0% 

Terminal rate 0/41 (0%) 

First incidence (days) -- 

Life table test P=0.583 

Logistic regression test P=0.602 

Cochran-Armitage test P=0.594 

Fisher exact test 

All Organs: Hemangiosarcoma 

Overall rate 3/64 (5%) 

Adjusted rate 7.1% 

Terminal rate 2/41 (5%) 

First incidence (days) 728 

Life table test P=0.459 

Logistic regression test P=0.497 

Cochran-Armitage test P=0.477 

Fisher exact test 

All Organs: Hemangioma or Hemangiosarcoma 

Overall rate 3/64 (5 %) 

Adjusted rate 7.1% 

Terminal rate 2/41 (5%) 

First incidence (days) 728 

Life table test P=0.320 

Logistic regression test P=0.353 

Cochran-Armitage test P=0.334 

Fisher exact test 

4/66 (6%) 0•63 (0%) 1/64 (2%) 

8.3% 0.0% 2.6% 

2/40 (5%) 0/42 (0%) 1/38 (3%) 

583 -- 729 (T) 

P=0.361 P=0.235N P=0.513N 

P=0.359 P=0.240N P=0.489N 

P=0.355 P=0.252N P=0.500N 

4/66 (6%) 1/63 (2%) 1/64 (2%) 

8.3% 2.4% 2.6% 

2/40 (5%) 1/42 (2%) 1/38 (3%) 

583 729 (T) 729 (T) 

P=0.519 P=0.299N P=0.324N 

P=0.532 P=0.304N P=0.291N 

P=0.517 P=0.315N P=0.310N 

3/66 (5%) 1/63 (2%) 1/64 (2%) 

6.9% 2.3% 2.6% 

2/40 (5%) 0/42 (0%) 1/38 (3%) 

657 681 729 (T) 

P=0.125 P=0.487 P=0.485 

P=0.136 P=0.501 P=0.485 

P=0.128 P=0.496 P=0.500 

6/66 (9%) 8/63 (13 %) 4/64 (6%) 

13.2% 17.3% 8.7% 

3/40 (8%) 5/42 (12%) 1/38 (3%) 

640 538 640 

P=0.249 P=0.112 P =0.483 

P=0.285 P=0.104 P=0.523 

P=0.262 P=0.098 P=0.500 

6/66 (9%) 9/63 (14%) 5/64 (8%) 

13.2% 18.9% 11.2% 

3/40 (8%) 5/42 (12%) 2/38 (5%) 

640 538 640 

P=0.249 P=0.073 P=0.340 

P=0.285 P=0.065 P=0.378 

P =0.262 P =0.060 P=0.359 
308 Nickel Oxide, NTP TR 451 

TABLE D3 

Statistical Analysis of Primary Neoplasms in Female Mice in the 2-Year Inhalation Study of Nickel Oxide (continued) 

0 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 5 mg/m 3 

All Organs: Malignant Lymphoma 

Overall rate 13/64 (20%) 

Adjusted rate 28.6% 

Terminal rate 9/41 (22%) 

First incidence (days) 618 

Life table test P=0.096N 

Logistic regression test P=0.065N 

Cochran-Armitage test P=0.075N 

Fisher exact test 

All Organs: Benign Neoplasms 

Overall rate 21/64 (33%) 

Adjusted rate 44.8 % 

Terminal rate 16/41 (39%) 

First incidence (days) 92 

Life table test P=0.343 

Logistic regression test P=0.462 

Cochran-Armitage test P=0.403 

Fisher exact test 

All Organs: Malignant Neoplasms 

Overall rate 30/64 (47 %) 

Adjusted rate 61.0% 

Terminal rate 22/41 (54%) 

First incidence .(days) 586 

Life table test P=0.315N 

Logistic regression test P=0.085N 

Cochran-Armitage test P=0.234N 

Fisher exact test 

All Organs: Benign or Malignant Neoplasms 

Overall rate 37/64 (58%) 

Adjusted rate 70.8% 

Terminal rate 26/41 (63%) 

First incidence (days) 92 

Life table test P=0.456 

Logistic regression test P=0.308N 

Cochran-Armitage test P=0.533N 

Fisher exact test 

12/66 (18%) 9/63 (14%) 7/64 (11%) 

25.3% 18.7% 15.8% 

6/40 (15%) 5/42 (12%) 4/38 (11%) 

597 321 426 

P=0.506N P=0.239N P=0.145N 

P=0.405N P=0.237N P=0.090N 

P=0.466N P= 0.254N P=0.111N 

28/66 (42%) 28/63 (44%) 24/64 (38%) 

55.9% 55.9% 53.0% 

19/40 (48%) 20/42 (48%) 17/38 (45%) 

162 587 619 

P=0.153 P=0.167 P=0.278 

P=0.214 P=0.137 P=0.313 

P=0.171 P=0.122 P=0.356 

37/66 (56%) 28/63 (44%) 28/64 (44%) 

64.6% 51.2% 49.9% 

20/40 (50%) 16/42 (38%) 11/38 (29%) 

469 321 426 

P=0.192 P=0.410N P=0.503N 

P=0.297 P=0.343N P=0.332N 

P=0.192 P=0.461N P=0.430N 

50/66 (76%) 45/63 (71%) 40/64 (63%) 

80.6% 77.6% 72.2% 

28/40 (70%) 29/42 (69%) 23/38 (61%) 

162 321 426 

P=0.052 P=0.174 P=0.300 

P=0.047 P=0.093 P=0.479 

P=0.023 P=0.078 P=0.359 

(T)Terminal sacrifice 

a Number of neoplasm-bearing animals/number of animals examined. Denominator is number of animals examined microscopically for adrenal gland, liver, 

lung, ovary, pituitary gland, spleen, and thyroid gland; for other tissues, denominator is number of animals necropsied. 

b Kaplan-Meier estimated neoplasm incidence at the end of the study after adjustment for intercurrent mortality 

c Observed incidence at terminal kill 

d Beneath the control incidence are the P values associated with the trend test. Beneath the exposed group incidence are the P values corresponding to 

pairwise comparisons between the controls and that exposed group. The life table test regards neoplasms in animals dying prior to terminal kill as being 

(directly or indirectly) the cause of death. The logistic regression test regards these lesions as nonfatal. The Cochran-Armitage and Fisher exact tests 

compare directly the overall incidence rates. For all tests, a negative trend or a lower incidence in an exposure group is indicated by N. 

e Not applicable; no neoplasms in animal group 
Lesions in Female Mice 309 

TABLE D4 

Historical Incidence of Alveolar/bronchiolar Neoplasms in Untreated Female B6C3F t Mice a 

Incidence in Controls 

Study Adenoma Carcinoma Adenoma or Carcinoma 

Historical Incidence at Lovelace Inhalation Toxicology Research Institute 

Nickel Oxide 2/64 4/64 6/64 

Nickel Subsulfide 3/58 7/58 9/58 

Nickel Sulfate Hexahydrate 3/61 4/61 7/61 

Talc 3/46 2/46 5/46 

Overall Historical Incidence in Inhalation Studies 

Total 6/944 (6.5%) 38/944 (4.0%) 

Standard deviation 3/1% 3.2% 

Range 0%-14% 0%-12% 

97/944 (10.3 %) 

3.7% 

0%-16% 

Overall Historical Incidence in Feed Studies 

Total 78/1,319 (5.9%) 26/1,319 (2.0%) 

Standard deviation 5.0% 2.3 % 

Range 0 %-24 % 0 % -8 % 

102/1,319 (7.7%) 

5.3% 

2%-26% 

a Data as of 17 June 1994 
310 Nickel Oxide, NTP TR 451 

TABLE D5 

Summary of the Incidence of Nonneoplastic Lesions in Female Mice in the 2-Year Inhalation Study of Nickel Oxide a 

0 mg/m ~ 1.25 mg/m 3 2.5 mg/m 3 5 mg/m ~ 

Disposition Summary 

Animals initially in study 74 76 74 

7-Month interim evaluation 5 5 5 

15-Month interim evaluation 5 5 5 

Early deaths 

Accidental deaths 1 1 

Moribund 15 18 9 

Natural deaths 7 8 11 

Survivors 

Terminal sacrifice 40 38 42 

Died last week of study 1 2 

Pregnant/Missexed 1 

Animals examined microscopically 74 76 73 

75 

5 

5 

16 

10 

38 

1 

74 

7-Month Interim Evaluation 

Genital System 

Uterus 

Inflammation, suppurative 

(1) 

1 (lOO%) 

Hematopoietic System 

Lymph node, bronchial 

Hyperplasia 

Pigmentation 

Lymph node, mandibular 

Hyperplasia, lymphoid 

Lymph node, mediastinal 

Hyperplasia 

Spleen 

Hyperplasia, lymphoid 

(3) (4) 

1 (25%) 

1 (25%) 

(1) 

~ 000%) 

(2) 

1 (50%) 

(1) 

1 (lOO%) 

(5) 

5 (lOO%) 

(5) 

5 (lOO%) 

(2) 

Respiratory System 

Lung 

Inflammation, chronic 

Alveolus, pigmentation 

Nose 

Olfactory epithelium, degeneration 

Respiratory epithelium, degeneration 

(5) 

(5) 

1 (20%) 

1 (20%) 

(5) 

1 (20%) 

4 (80%) 

(5) 

(5) 

4 (80%) 

5 000%) 

(5) 

(5) 

4 (80%) 

5 (100%) 

(5) 

Urinary System 

Kidney 

Infiltration cellular, lymphocyte 

(5) 

1 (20%) 

(5) 

2 (40%) 

(5) 

1 (20%) 

(5) 

2 (40%) 
Lesions in Female Mice 311 

TABLE D5 

Summary of the Incidence of Nonneoplastic Lesions in Female Mice in the 2-Year Inhalation Study of Nickel Oxide 

(continued) 

0 mg/m a 1.25 mg/m a 2.5 mg/m 3 5 mg/m 3 

7-Month Interim Evaluation (continued) 

Systems Examined With No Lesions Observed 

Alimentary System 

Cardiovascular System 

Endocrine System 

General Body System 

Integumentary System 

Musculoskeletal System 

Nervous System 

Special Senses System 

15-Month Interim Evaluation 

Alimentary Sygtem 

Liver 

Infiltration cellular, lymphocyte 

Inflammation, chronic 

(5) (5) 

1 (20%) 

(5) 

1 (20%) 

(5) 

Cardiovascular System 

Heart 

Venule, inflammation, chronic active 

(5) (5) (5) (5) 

1 (20%) 

Endocrine System 

Adrenal cortex 

Infiltration cellular 

Pituitary gland 

Pars distalis, angiectasis 

(5) 

I (20%) 

(5) 

(5) 

(5) 

(5) 

(5) 

1 (20%) 

(5) 

(5) 

Genital System 

Ovary 

Cyst 

Uterus 

Bilateral, endometrium, hyperplasia 

Endometrium, hyperplasia 

(5) 

(5) 

1 (20%) 

3 (60%) 

(5) 

1 (20%) 

(5) 

5 (100%) 

(5) 

(5) 

5 (100%) 

(5) 

(5) 

5 (100%) 

Hematopoietic System 

Lymph node, bronchial 

Hyperplasia, lymphoid 

Pigmentation 

Lymph node, maodibular 

Hyperplasia, lymphoid 

Lymph node, mediastinal 

Hyperplasia, lymphoid 

Spleen 

Hyperplasia, lymphoid 

(5) 

(5) 

(2) 

(5) 

1 (20%) 

(5) 

3 (60%) 

4 (80%) 

(5) 

2 (40%) 

(4) 

1 (25%) 

(5) 

2 (40%) 

(5) 

4 (80%) 

5 (lOO%) 

(5) 

(3) 

(5) 

1 (20%) 

(5) 

4 (80%) 

5 (lOO%) 

(5) 

(2) 

(5) 
312 Nickel Oxide, NTP TR 451 

TABLE D5 

Summary of the Incidence of Nonneoplastic Lesions in Female Mice in the 2-Year Inhalation Study of Nickel Oxide 

(continued) 

0 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 5 mg/m 3 

15-Month Interim Evaluation (continued) 

Respiratory System 

Lung (5) 

Inflammation, chronic 

Bronchialization b 

Alveolus, pigmentation 

Alveolus, proteinosis 

Nose (5) 

Olfactory epithelium, degeneration 2 (40%) 

Respiratory epithelium, degeneration 1 (20%) 

(5) (5) (5) 

2 (40%) 4 (80%) 4 (80%) 

3 (60%) 3 (60%) 

4 (80%) 5 (100%) 5 (100%) 

3 (60%) 

(5) (5) (5) 

1 (20%) 2 (40%) 3 (60%) 

Special Senses System 

Ear 

External ear, hemorrhage 

(1) 

1 (100%) 

Systems Examined With No Lesions Observed 

General Body System 

Integumentary System 

Musculoskeletal System 

Nervous System 

Urinary System 

2- Year Study 

Alimentary System 

Gallbladder (60) (59) (57) (56) 

Inflammation, suppurative 1 (2%) 

Intestine large, cecum (60) (60) (57) (56) 

Hyperplasia, lymphoid 1 (2%) 4 (7%) 1 (2%) 

Intestine small, duodenum (60) (60) (56) (56) 

Hyperplasia, lymphoid 2 (4%) 

Inflammation, suppurative 1 (2%) 

Intestine small, ileum (58) (57) (56) (54) 

Hyperplasia, lymphoid 2 (4%) 

Liver (64) (66) (63) (63) 

Abscess 1 (2%) 

Basophilicfocus 1 (2%) 1 (2%) 1 (2%) 1 (2%) 

Clear cell focus 2 (3%) 1 (2%) 1 (2%) 

Eosinophilic focus 2 (3%) 2 (3%) 

Inflammation, chronic 1 (2%) 

Inflammation, chronic, focal 1 (2%) 3 (5%) 3 (5%) 

Mixed cell focus 1 (2%) 

Hepatocyte, fatty change 1 (2%) 

Hepatocyte, hyperplasia 1 (2%) 

Hepatocyte, necrosis 1 (2%) 1 (2%) 3 (5%) 

Hepatocyte, vacuolization cytoplasmic 1 (2%) 1 (2%) 

Sinusoid, amyloid deposition 1 (2 %) 

Mesentery (2) (2) (1) (3) 

Inflammation, chronic active 1 (33%) 

Artery, inflammation, chronic 2 (100%) 

Fat, necrosis 1 (33%) 
Lesions in Female Mice 313 

TABLE D5 

Summary of the Incidence of Nonneoplastic Lesions in Female Mice in the 2-Year Inhalation Study of Nickel Oxide 

(continued) 

0 mg/m 3 1.25 mg/m 5 2.5 mg/m 3 5 mg/m 3 

2-Year Study (continued) 

Alimentary System (continued) 

Pancreas (64) 

Atrophy 

Congestion 

Cyst 

Infiltration cellular, lymphocyte 

Inflammation, chronic 

Inflammation, suppurative 

Stomach, forestomach (64) 

Hypcrkera~osis 1 

Hyperplasia, squamous 

Inflammation, chronic 1 

Inflammation, suppurative 

Stomach, glandular (63) 

Inflammation, chronic 1 

Inflammation, suppurative 

Tooth (2) 

Developmental malformation l 

Inflammation I 

(2%) 

(2%) 

(2%) 

(50%) 

(50%) 

(66) (62) (62) 

1 (2%) 

1 (2%) 

I (2%) 

1 (2%) 

1 (2%) 

1 (2%) 

(63) (62) 

8 (13%) 2 (3%) 

(60) 

I (2%) 

1 (2%) 

1 (2%) 

(63) (62) (60) 

(1) 

1 (lOO%) 

1 (2%) 

(1) 

1 (100%) 

(2) 

1 (50%) 

Cardiovascular System 

Heart 

Inflammation~ chronic active 

Inflammation, suppurative 

Arteriole, inflammation, chronic 

(64) 

1 (2%) 

(66) (63) 

1, (2%) 

1 (2%) 

(64) 

Endocrine System 

Adrenal cortex 

Hyperplasia 

Vacuolization cytoplasmic 

Spindle cell, hyperplasia 

Adrenal medulla " 

Degeneration 

Hyperplasia 

Spindle cell, hyperplasia 

Islets, pancreatic 

Hyperplasia 

Pituitary gland 

Pars distalis, angiectasis 

Pars distalis, hyperplasia 

Pars distalis, necrosis 

Thyroid gland 

Hyperplasia, cystic 

Infiltration cellular, lymphocyte 

Inflammation, suppurative 

(64) 

1 (2%) 

1 (2%) 

4 (6%) 

(62) 

1 (2%) 

1 (2%) 

1 (2%) 

(63) 

(63) 

7 (11%) 

10 (16%) 

(62) 

26 (42 %) 

1 (2%) 

(66) 

2 (3%) 

2 (3%) 

(65) 

2 (3%) 

(65) 

1 (2%) 

(66) 

l0 (15%) 

9 (14%) 

(66) 

26 (39%) 

2 (3%) 

(63) 

1 (2%) 

(63) 

(62) 

(61) 

11 (18%) 

4 (7%) 

(63) 

32 (51%) 

(62) 

1 (2%) 

1 (2%) 

(62) 

(62) 

(62) 

7 (11%) 

9 (15%) 

1 (2%) 

(64) 

26 (41%) 

General Body System 

None 
314 Nickel Oxide, NTP TR 451 

TABLE D5 

Summary of the Incidence of Nonneoplastic Lesions in Female Mice in the 2-Year Inhalation Study of Nickel Oxide 

(continued) 

0 mg/m ~ 1.25 mg/m 3 2.5 mg/m 3 5 mg/m 3 

2-Year Study (continued) 

Genital System 

Clitoral gland (57) (62) (57) (55) 

Ectasia 1 (2%) 2 (3%) 3 (5%) 

Inflammation, chronic 2 (4%) 1 (2%) 

Inflammation, chronic active 1 (2%) 

Pigmentation 5 (9%) 4 (6%) 5 (9%) 12 (22%) 

Ovary (61) (66) (60) (63) 

Abscess 2 (3%) 

Angiectasis 2 (3%) 

Congestion 1 (2%) 

Cyst 8 (13%) 14 (21%) 9 (15%) 7 (11%) 

Inflammation, suppurative 1 (2%) 1 (2%) 

Rete ovarii, thrombosis 1 (2%) 

Uterus (64) (66) (62) (63) 

Cyst 1 (2%) 

Dilatation 1 (2%) 

Inflammation, suppurative i (2%) 1 (2%) 

Bilateral, dilatation 1 (2%) 

Endometrium, hyperplasia, cystic 24 (38%) 34 (52%) 30 (48%) 29 (46%) 

I-Iematopoietic System 

Bone marrow (64) (65) 

Myelofibrosis 3 (5%) 2 (3%) 

Necrosis 1 (2%) 

Myeloid cell, hyperplasia 5 (8%) 4 (6%) 

Lymph node (15) (9) 

Iliac, hyperplasia, lymphoid 3 (20%) 2 (22%) 

Iliac, hyperplasia, macrophage 

Iliac, pigmentation 1 (11%) 

Pancreatic, hyperplasia, lymphoid 

Renal, hyperplasia, lymphoid 4 (27%) 1 (11%) 

Renal, inflammation, chronic active 

Lymph node, bronchial (54) (63) 

Congestion 2 (3%) 

Hyperplasia, lymphoid 14 (26%) 37 (59%) 

Pigmentation 58 (92%) 

Lymph node, mandibular (61) (63) 

Congestion 1 (2%) 

Hyperplasia, lymphoid 16 (26%) t8 (29%) 

Hyperplasia, macrophage 1 (2%) 

Inflammation, suppurative 

Lymph node, mesenteric (54) (63) 

Congestion 4 (6%) 

Ectasia 1 (2%) 

Hematopoietic cell proliferation • 

Hyperplasia, lymphoid 8 (15%) 3 (5%) 

Inflammation 

Inflammation, chronic active 

Inflammation, suppurative 1 (2%) 

(62) (63) 

2 (3%) 

1 (2%) 

3 (5%) 1 (2%) 

(10) (9) 

1 (10%) 1 (11%) 

1 (11%) 

1 (10%) 1 (11%) 

1 (10%) 2 (22%) 

1 (11%) 

(59) (62) 

1 (2%) 2 (3%) 

40 (68%) 44 (71%) 

56 (95%) 60 (97%) 

(59) (58) 

1 (2%) 

18 (31%) 14 (24%) 

1 (2%) 

(54) (55) 

1 (2%) 1 (2%) 

8 (15%) 

1 (2%) 

1 (2%) 

1 (2%) 

13 (24%) 
Lesions in Female Mice 315 

TABLE D5 

Summary of the Incidence of Nonneoplastic Lesions in Female Mice in the 2-Year Inhalation Study of Nickel Oxide 

(continued) 

0 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 5 mg/m 3 

2-Year Study (continued) 

Hematopoietic System (continued) 

Lymph node, mediastinal (35) 

Hyperplasia, lymphoid 1 (3%) 

Pigmentation 

Spleen (64) 

Congestion 

Hematopoietic cell proliferation 8 (13 %) 

Hyperplasia, lymphoid 12 (19%) 

Hyperplasia, macrophage 

Thymus (59) 

Atrophy 1 (2 %) 

Hyperplasia, lymphoid 1 (2%) 

(28) 

3 (11%) 

2 (7%) 

(66) 

6 (9%) 

17 (26%) 

1 (2%) 

(61) 

(33) (29) 

3 (9%) 2 (7%) 

1 (3%) 5 (17%) 

(63) (63) 

2 (3%) 

8 (13%) 5 (8%) 

22 (35%) 17 (27%) 

1 (2%) 

(60) (57) 

1 (2%) 

Integumentary System 

Mammary gland 

Hyperplasia, glandular 

Skin 

Alopecia 

Edema 

Hemorrhage 

Inflammation, chronic 

Inflammation, chronic active 

Inflammation, suppurative 

Epidermis, inflammation, suppurati4e 

Pinna, cyst epithelial inclusion 

Subcutaneous tissue, edema 

Subcutaneous tissue, inflammation, chronic 

active 

Subcutaneous tissue, inflammation, 

suppurative 

Subcutaneous tissue, necrosis 

(63) 

6 (10%) 

(4) 

1 (25%) 

1 (25%) 

(66) 

4 (6%) 

(8) 

1 (13%) 

1 (13%) 

1 (13%) 

(63) 

8 (13%) 

(6) 

1 (17%) 

1 (17%) 

1 (17%) 

(63) 

8 (13%) 

(12) 

1 (8%) 

1 (8%) 

2 (17%) 

1 (8%) 

1 (8%) 

1 (8%) 

1 (8%) 

Musculoskeletal System 

Bone 

Fracture 

Hyperostosis 

Pelvis, fracture 

(64) 

1 (2%) 

17 (27%) 

(65) 

25 (38%) 

(63) 

26 (41%) 

(63) 

24 (38%) 

1 (2%) 

Nervous System 

Brain 

tlypothalamus, compression 

Pons, compressiou 

Spinal cord 

tlemorrhage 

(64) (66) 

2 (3%) 

1 (2%) 

(1) 

1 (100%) 

(63) 

6 (10%) 

(64) 

4 (6%) 

Respiratory System 

Larynx 

ll~flammation, suppurative 

(62) (63) (62) (63) 

I (2%) 1 (2%) 
316 Nickel Oxide, NTP TR 451 

TABLE D5 

Summary of the Incidence of Nonneoplastic Lesions in Female Mice in the 2-Year Inhalation Study of Nickel Oxide 

(continued) 

0 mg/m 3 1.25 mg/m 3 2.5 mg/m ~ 5 mg/m z 

2-Year Study (continued) 

Respiratory System (contirmed) 

Lung (64) 

Fibrosis 

Hemorrhage 

Inflammation, chronic 7 (11%) 

Inflammation, chronic active 

Metaplasia, squamous 

Pigmentation, hemosiderin 2 (3%) 

Bronchialization b 

Alveolar epithelium, hyperplasia, focal 

Alveolus, hemorrhage 

Alveolus, hyperplasia, macrophage 1 (2%) 

Alveolus, pigmentation 

Alveolus, proteinosis 

Nose (62) 

Inflammation, suppurative 

Capillary, thrombosis 1 (2%) 

Olfactory epithelium, degeneration 16 (26%) 

Respiratory epithelium, degeneration 19 (31%) 

Respiratory epithelium, hyperplasia 1 (2%) 

Respiratory epithelium, inflammation, chronic 

Respiratory epithelium, inflammation, 

suppurative 

Respiratory epithelium, metaplasia, squamous 

17 (27%) 

10 (16%) 

(66) (63) 

1 (2%) 

2 (3%) 

43 (65%) 53 (84%) 

1 (2%) 

35 (53%) 39 (62%) 

1 (2%) 

1 (2%) 

2 (3%) 

64 (97%) 61 (97%) 

8 (12%) 17 (27%) 

(65) (62) 

1 (2%) 

10 (15%) 2 (3%) 

15 (23%) 11 (18%) 

1 (2%) 

1 (2%) 

(64) 

3 (5%) 

52 (81%) 

1 (2%) 

40 (63%) 

64 (100%) 

29 (45%) 

(62) 

7 (11%) 

17 (27%) 

18 (28%) 18 (29%) 21 (34%) 

9 (14%) 14 (23%) 15 (24%) 

Special Senses System 

Ear 

External ear, hyperkeratosis 

Eye 

Cornea, inflammation 

(2) (1) (1) 

1 (100%) 

(1) 

(2) 

2 (100%) 

Urinary System 

Kidney (64) 

Hydronephrosis 1 (2%) 

Infiltration cellular, lymphocyte 

Inflammation, chronic 

Metaplasia, osseous 1 (2%) 

Necrosis 

Nephropathy 2 (3%) 

Cortex, cyst 

Glomemlus, thrombosis 1 (2%) 

Medulla, cyst 

Pelvis, infiltration cellular, lymphocyte 

Renal tubule, hyperplasia 1 (2%) 

Urethra 

Concretion 

Urinary bladder (63) 

Inflammation, suppurative 

(66) 

1 (2%) 

(63) 

2 (3%) 

2 (3%) 

3 (5%) 3 (5%) 

1 (2%) 

1 (2%) 

(62) (60) 

I (2%) 

(63) 

1 (2%) 

2 (3%) 

1 (2%) 

(l) 

1 (100%) 

(57) 

Number of animals examined microscopically at site and number of animals with lesion 

This alteration is associated with injury to the parenchyma around the terminal bronchiole. It is listed as "alveolar epithelial hyperplasia" in the TDMS 

data tables for mice in this study. 
317 

APPENDIX E 

GENETIC TOXICOLOGY 

MOUSE PERIPHERAL BLOOD MICRONUCLEUS TEST PROTOCOL ......................... 318 

RESULTS ........................................................... 318 

TABLE E1 Frequency of Micronuclei in Mouse Peripheral Blood Erythrocytes 

Following Treatment with Nickel Oxide by Inhalation for 13 Weeks ............. 319 
318 Nickel Oxide, NTP TR 451 

GENETIC TOXICOLOGY 

MOUSE PERIPHERAL BLOOD MICRONUCLEUS TEST PROTOCOL 

A detailed discussion of this assay is presented in MacGregor et al. (1990). At the end of the 13-week 

toxicity study, peripheral blood samples were obtained from male and female B6C3F l mice and smears 

were immediately prepared and fixed in absolute methanol. The methanol-fixed slides were stained with a 

chromatin-specific fluorescent dye mixture of Hoechst 33258/pyronin Y (MacGregor et al., 1983) and 

coded. Ten thousand normochromatic erythrocytes (NCEs) were scored in each of 10 animals per dose 

group. The criteria of Schmid (1976) were used to define micronuclei. 

The results were tabulated as the mean of the pooled results from all animals within a treatment group, 

plus or minus the standard error of the mean. The frequency of micronucleated cells among NCEs was 

analyzed by a statistical software package that tested for increasing trend over exposure groups using a 

one-tailed Cochran-Armitage trend test, followed by pairwise comparisons between each exposure group 

and the control group (Margolin et al., 1990). In the presence of excess binomial variation, as detected 

by h binomial dispersion test, the binomial variance of the Cochran-Armitage test was adjusted upward in 

proportion to the excess variation. In the micronucleus test, an individual trial is considered positive if 

1) the trend test P value is less than or equal to 0.025 or 2) the P value for any single exposure group is 

less than or equal to 0.025/N where N equals the number of exposure groups. A final call of positive for 

micronucleus induction is preferably based on reproducibly positive trials (as noted above). Ultimately, 

the final call is determined by the scientific staff after considering the results of statistical analyses, 

reproducibility of any effects observed, and the magnitudes of those effects. 

RESULTS 

Nickel oxide was tested for induction of micronuclci in normochromatic erythrocytes of male and female 

mice exposed by inhalation for 13 weeks. The compound did not induce an increase in the frequency of 

micronucleated NCEs in peripheral blood samples (Table El), 
Genetic Toxicology 319 

TABLE E1 

Frequency of Micronuclei in Mouse Peripheral Blood Erythrocytes Following Treatment 

with Nickel Oxide by Inhalation for 13 Weeks a 

Micronucleated 

Dose Normochromatic Number 

(mg/m 3) Erythrocytes/1,000 Cells b of Mice 

Male 

Trend test 

0 0.946 ± 1.26 10 

1.3 0.809 ± 1.03 10 

2.5 0.987 ± 0,91 10 

5.0 0.954 ± 0.89 10 

P=0.319 c 

Female 

Trend test 

Urethane d 

0 0.548 ± 0.88 10 

1.3 0.504 ± 0.64 10 

2.5 0.697 ± 0.47 10 

5.0 0.571 ± 0.57 10 

P=0.295 

0.2 13.376 ± 0.724* 

* P<0.001 

a Slides scored at SRI, International. The detailed protocol and these data are presented by MacGregor et al. (1990); 10,000 NCEs scored 

per animal. 

b Data presented as mean ± standard error of the mean. NCE = normochromatic erythrocyte. 

c Significance of micronucleated NCEs determined by a one-tailed Cochran-Armitage trend test. 

d Urethane was used as the positive control and the dose is presented in parts per million. 
320 Nickel Oxide, NTP TR 451 
321 

APPENDIX F 

ORGAN WEIGHTS 

AND ORGAN-WEIGHT-TO-BODY-WEIGHT RATIOS 

TABLE F1 

TABLE F2 

TABLE F3 

TABLE F4 

TABLE F5 

TABLE F6 

TABLE F7 

TABLE F8 

Organ Weights and Organ-Weight-to-Body-Weight Ratios for Rats 

in the 16-Day Inhalation Study of Nickel Oxide .......................... 322 

Organ Weights and Organ-Weight-to-Body-Weight Ratios for Rats 

in the 13-Week Inhalation Study of Nickel Oxide ........................ 323 

Organ Weights and Organ-Weight-to-Body-Weight Ratios for Rats 

at the 7-Month Interim Evaluation in the 2-Year Inhalation Study 

of Nickel Oxide .............................................. 324 

Organ Weights and Organ-Weight-to-Body-Weight Ratios for Rats 

at the 15-Month Interim Evaluation in the 2-Year Inhalation Study 

of Nickel Oxide .............................................. 325 

Organ Weights and Organ-Weight-to-Body-Weight Ratios for Mice 

in the 16-Day Inhalation Study of Nickel Oxide .......................... 326 

Organ Weights and Organ-Weight-to-Body-Weight Ratios for Mice 

in the 13-Week Inhalation Study of Nickel Oxide ........................ 327 

Organ Weights and Organ-Weight-to-Body-Weight Ratios for Mice 

at the 7-Month Interim Evaluation in the 2-Year Inhalation Study 

of Nickel Oxide .............................................. 328 

Organ Weights and Organ-Weight-to-Body-Weight Ratios for ~Mice 

at the 15-Month Interim Evaluation in the 2-Year Inhalation Study 

of Nickel Oxide .............................................. 329 
322 Nickel Oxide, NTP TR 451 

TABLE F1 

Organ Weights and Organ-Weight-to-Body-Weight Ratios for Rats in the 16-Day Inhalation Study of Nickel Oxide a 

0 mg/m 3 1.2 mg/m ~ 2.5 mg/m 3 5 mg/m 3 10 mg/m a 30 mg/m 3 

n 5 5 5 5 5 5 

Male 

Necropsy body wt 213 ± 5 211 5:4 214 ± 6 210 ± 4 210 5:4 204 5:5 

Brain 

Absolute 1.744 5:0,022 1.774 5:0.010 1.748 ± 0.017 1.732 ± 0.017 1.726 5:0.019 1.710 ± 0.019 

Relative 8.20 5:0.15 8.42 5:0.12 8.17 5:0.16 8,24 5:0.10 8,22 ± 0.17 8.42 ± 0.18 

Heart 

Absolute 0.818 5:0.037 0.782 5:0.044 0.840 ± 0.047 0.846 ± 0.070 0.780 5:0.022 0.834 ± 0.039 

Relative 3,84 5:0,15 3.71 5:0.23 3.91 ± 0.16 4.02 5:0.30 3.72 5:0.15 4.13 ± 0.31 

R. Kidney 

Absolute 0.851 5:0.034 0.842 5:0.025 0.883 ± 0.047 0.817 ± 0.022 0.806 ± 0.033 0.807 ± 0.023 

Relative 3.99 5:0.14 3.99 ± 0.11 4.12 ± 0.21 3.89 5:0.11 3.83 ± 0.09 3.97 ± 0.07 

Liver 

Absolute 10.020 5:0.291 10.080 ± 0.159 9.780 ± 0.426 9.840 5:0.121 10.040 ± 0.339 9.280 ± 0.267 

Relative 47.03 ± 0.71 47.83 ± 0.99 45.58 ± 1.33 46.84 5:0.81 47.73 ± 1.19 45.58 ± 0.28 

Lung 

Absolute 1.060 5:0.040 1.000 ± 0.032 1,060 5:0.040 0.960 ± 0.024 1.200 ± 0.032* 1.360 ± 0.051"* 

Relative 4.98 ± 0.20 4.74 ± 0.14 4.94 ± 0.15 4.56 ± 0.07 5.72 ± 0.24** 6.68 ± 0.13"* 

Testes 

Absolute 1.188 5:0.013 1.214 5:0.016 1.258 5:0.046 1.210 =[: 0.033 1.242 5:0.017 1.222 ± 0.025 

Relative 5.59 5:0.09 5.76 5:0.12 5.87 ± 0.19 5.76 5:0.16 5.92 5:0.16 6.01 ± 0.05 

Thymus 

Absolute 0.351 ± 0.008 0.363 ± 0.015 0.353 ± 0.011 0.323 5:0.024 0.369 ± 0.009 0.341 ± 0.029 

Relative 1.65 5:0.05 1.72 ± 0.07 1.66 5:0.09 1.54 ± 0.12 1.76 5:0.06 1.67 ± 0.11 

Female 

Necropsy body wt 150 ± 2 155 ± 3 154 ± 4 156 ± 2 150 ± 2 149 ± 3 

Brain 

Absolute 1.650 5:0.013 1.652 5:0.020 1.662 ± 0.019 1,652 ± 0,018 

Relative 11.03 ± 0.17 10.71 5:0.22 1'0.83 ± 0.20 10.63 ± 0.20 

Heart 

Absolute 0,558 5:0.016 0,600 5:0.024 0.602 ± 0,023 0,620 ± 0,011 

Relative 3.73 ± 0,09 3.88 5:0.09 3.92 ± 0.12 3.99 5:0.11 

R. Kidney 

Absolute 0,624 ± 0.007 0,642 ± 0,014 0.599 5:0.024 0,608 ± 0,014 

Relative 4.17 ± 0.05 4.16 5:0.11 3.89 ± 0.13 3.91 ± 0.09 

Liver 

Absolute 5.900 ± 0.164 6,560 ± 0.178 6.440 ± 0.238 5~980 5:0,153 

Relative 39.40 5:0.78 42.48 ± 0.89 41.88 ± 1.18 38.43 5:0.74 

Lung 

Absolute 0.780 ± 0.020 0.860 ± 0.040 0.900 ± 0.032 0,820 ± 0.020 

Relative 5.21 ± 0.11 5.56 5:0.18 5.86 ± 0.21 5.27 ± 0.14 

Thymus 

Absolute 0.293 5:0.011 0.323 5:0.019 0.301 ± 0.015 0.300 ± 0.012 

Relative 1.95 ± 0.07 2.09 ± 0.11 1.95 5:0.06 1.93 ± 0.06 

1.702 ± 0.022 1,634 ± 0,047 

11.32 5:0.14 10.99 ± 0.29 

0,590 5:0,030 0,620 ± 0,027 

3,92 5:0.15 4.16 5:0.14 

0,637 5:0,025 0,628 ± 0,017 

4.24 5:0.16 4.22 ± 0.08 

6.120 ± 0.235 5,520 ± 0,208 

40.64 5:1.07 37.06 ± 0.94 

1.040 ± 0.024** 1.120 ± 0.037** 

6.91 ± 0.12"* 7.52 ± 0.11"* 

0.291 ± 0.015 0.302 ± 0.021 

1.93 5:0.08 2.02 ± 0.12 

* Significantly different (P <_0.05) from the control group by Williams' or Dunnett's test 

** P_<0.01 

a Organ weights and body weights are given in grams; organ-weight-to-body-weight ratios are given as mg organ weight/g body weight 

(mean 5: standard error). 
Organ Weight Analyses 323 

TABLE F2 

Organ Weights and Organ-Weight-to-Body-Weight Ratios for Rats in the 13-Week Inhalation Study of Nickel Oxide a 

0 mg/m 3 0.6 mg/m 3 1.2 mg/m 3 2.5 mg/m 3 5 mg/m 3 10 mg/m 3 

n 10 10 10 9 10 10 

Necropsy body wt 310 ± 8 312 ± 6 314 ± 6 297 ± 5 304 ± 6 301 ± 5 

Brain 

Absolute 1.853 ± 0.019 1.893 ± 0.018 1.,904 ± 0.023 1.849 ± 0.018 1.870 ± 0.019 1.880 ± 0.010 

Relative 6.00 ± 0.12 6,08 ± 0.08 6.08 ± 0.09 6.23 ± 0.07 6.17 ± 0.12 6.26 5:0.08 

Heart 

Absolute 0,902 ± 0,029 0,898 ± 0,024 0,926 ± 0,023 0,852 ± 0.031 0.894 ± 0.029 0.911 ± 0.015 

Relative 2.91 ± 0.06 2,88 ± 0.07 2.95 ± 0.06 2.86 ± 0.07 2.94 ± 0.07 3.03 ± 0.06 

R. Kidney 

Absolute 1.029 ± 0.038 1.052 ± 0.026 1.064 ± 0.028 0.991 ± 0.015 0.984 ± 0.022 1.042 ± 0.019 

Relative 3.32 ± 0.10 3.38 ± 0.10 3.39 ± 0.07 3.34 ± 0.06 3.24 ± 0.06 3.46 ± 0.05 

Liver 

Absolute 10.560 ± 0.392 11.150 ± 0.202 10.880 ± 0.235 10.644 ± 0.245 10.430 ± 0.238 10.720 ± 0.199 

Relative 34.06 ± 0.93 35.77 ± 0.33 34.69 ± 0.31 35.84 ± 0.58 34.29 ± 0.44 35.63 ± 0.51 

Lung 

Absolute 1.180 ± 0.037 1.349 ± 0.024** 1.474 ± 0.041"* 1.698 ± 0.053** 1.906 ± 0.032** 2.467 ± 0.045** 

Relative 3.81 ± 0.11 4.33 ± 0.09** 4.70 ± 0.I1"* 5.73 ± 0.19"* 6.27 ± 0.05** 8.21 ± 0.19"* 

R. Testis 

Absolute 1.340 ± 0.028 1.429 ± 0.024 1.479 ± 0.054 1.438 ± 0.037 1.418 ± 0.034 1.455 ± 0.054 

Relative 4.34 ± 0.12 4.60 ± 0.12 4.72 ± 0.15 4.84 ± 0.10" 4.67 ± 0.12" 4.84 ± 0.17" 

Thymus 

Absolute 0.283 ± 0.014 0.281 ± 0.018 0.266 ± 0.006 0.254 ± 0.015 0.249 ± 0.004 0.259 ± 0.010 

Relative 0.92 ± 0.06 0.90 ± 0.05 0.85 ± 0.02 0.86 ± 0.05 0.82 ± 0.01 0.86 ± 0.04 

Female 

n 10 10 10 10 10 10 

Necropsy body wt 192 ± 6 182 ± 6 189 ± 3 192 ± 4 189 ± 5 195:2:5 

Brain 

Absolute 1,791 ± 0.030 1.685 ± 0.060 1.767 ± 0.011 1.765 ± 0.019 1.740 ± 0.025 1.766 ± 0.021 

Relative 9.38 ± 0.15 9.35 ± 0.45 9.35 ± 0.13 9.21 ± 0.15 9.26 ± 0.23 9.10 ± 0.16 

Heart 

Absolute 0.663 ± 0.021 0.606 ± 0.008 0.659 ± 0.014 0.688 ± 0.039 0.604 ± 0.013 0.672 ± 0.020 

Relative 3.47 ± 0.08 3.36 ± 0.11 3.49 ± 0.09 3.58 ± 0.20 3.20 ± 0.05 3.45 ± 0.07 

R. Kidney 

Absolute 0.667 ± 0.021 0.661 ± 0.015 0,664 ± 0.014 0.667 ± 0.019 0,642 ± 0.016 0.688 ± 0.017 

Relative 3.49 ± 0.11 3.66 ± 0.12 3.51 ± 0.05 3.47 ± 0.09 3.41 ± 0.07 3.54 ± 0.06 

Liver 

Absolute 6.730 ± 0.171 5.870 ± 0,360* 6.540 ± 0.115 6.740 ± 0.194 6.300 ± 0.180 6.890 ± 0.161 

Relative 35.17 ± 0.35 32.00 ± 1.17"* 34.57 ± 0.52 35.04 ± 0.51 33.38 ± 0.51 35.41 ± 0.30 

Lung 

Absolute 0.983 ± 0.026 1.027 ± 0,023 1.134 ± 0.024* 1.550 ± 0.038** 1.610 ± 0.047** 2.111 ± 0.081"* 

Relative 5.14 ± 0.10 5.68 ± 0,17" 6.00 ± 0.11"* 8.06 ± 0.10"* 8.55 ± 0.23** 10.84 ± 0.31"* 

Thymus 

Absolute 0.241 ± 0.008 0.224 ± 0,008 0.219 ± 0.007 0.237 ± 0.007 0.229 ± 0.008 0.235 ± 0.009 

Relative 1.26 ± 0.05 1.23 ± 0,03 1.16 ± 0.03 1.24 ± 0.04 1.21 ± 0.04 1.20 ± 0.02 

* Significantly different (P<_0.05) from the control group by Williams' or Durmett's test 

** P_<0.01 

a Organ weights and body weights are given in grams; organ-weight-to-body-weight ratios are given as mg organ weight/g body weight 

(mean ± standard error). 
324 Nickel Oxide, NTP TR 451 

TABLE F3 

Organ Weights and Organ-Weight-to-Body-Weight Ratios for Rats at the 7-Month Interim Evaluation 

in the 2-Year Inhalation Study of Nickel Oxide a 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 

Male 

n 6 7 7 7 

Necropsy body wt 391 ± 10 390 ± 5 402 ~ 9 407 ± 10 

Brain 

Absolute 2.030 ± 0.016 " 2.004 ± 0.037 2.037 ± 0.017 2.061 ::k 0.018 

Relative 5.21 ± 0.12 5.14 ± 0.I1 5.09 ± 0.12 5.08 ± 0.10 

R. Kidney 

Absolute 1.293 ± 0.047 1.363 ± 0.036 1.404 ± 0.042 1.464 ± 0.040** 

Relative 3.31 ± 0.10 3.49 ± 0,08 3.50 ± 0.07 3,61 ± 0.10 

Liver 

Absolute 13.883 ± 1.071 14.131 ± 0.469 15.113 ± 0.595 16.559 ± 0.760* 

Relative 35.44 ± 2.37 36.16 ± 0.82 37.62 ± 1.13 40.74 ± 1.78" 

Lung 

Absolute 1.718 ± 0.072 1.850 ± 0.071 2.426 ± 0.107"* 2,593 ± 0.060** 

Relative 4.40 ± 0.14 4.74 ± 0.17 6.04 ± 0.22** 6.40 ± 0.24** 

Spleen 

Absolute 0.773 ± 0.030 0.759 ± 0.023 0.757 ± 0.017 0.756 ::k 0.022 

Relative 1.98 ± 0.06 1.94 ± 0.05 1.89 ± 0.05 1.86 ± 0.04 

R. Testis 

Absolute 1.508 ± 0.034 1.580 ± 0.025 1.541 ± 0.027 1.526 ± 0.033 

Relative 3.87 ± 0.09 4.05 ::k 0.06 3,84 ± 0.05 3.76 5:0.12 

Thymus 

Absolute 0.253 ± 0.027 0.272 ± 0.022 0.268 ± 0.031 0.272 ± 0.024 

Relative 0.65 ± 0.07 0.70 ± 0.06 0.66 ± 0.06 0.67 ± 0.05 

Female 

n 7 7 

Necropsy body wt 234 ± 4 234 ± 2 

Brain 

Absolute 1.857 ± 0.013 1.877 ± 0.018 

Relative 7.95 ± 0.15 8.02 ± 0.08 

R. Kidney 

Absolute 0.851 ± 0.029 0.886 ± 0.016 

Relative 3.65 ± 0.17 3.79 ± 0.06 

Liver 

Absolute 8.284 ± 0.314 8.829 ± 0.305 

Relative 35.43 ± 1.31 37.72 ± 1.20 

Lung 

Absolute 1.140 ± 0.028 1.310 ± 0.026* 

Relative 4.89 ± 0.19 5.60 ± 0.09* 

Spleen 

Absolute 0.526 ± 0.008 0.519 ± 0.009 

Relative 2.25 ± 0.03 2.22 ± 0.04 

Thymus 

Absolute 0.227 ± 0.023 0.212 ± 0.018 

Relative 0.97 ± 0.09 0.90 ± 0.07 

7 6 

236 ± 4 232 ± 6 

1.880 ± 0,013 1,888 ± 0.014 

7.98 ± 0,14 8.18 ± 0.21 

0.826 ± 0,040 0.845 ± 0.037 

3,50 ± 0.15 3.64 ± 0.07 

8.304 ± 0,391 8.502 ± 0.327 

35.19 ± 1.49 36.72 ± 1.06 

1.647 ± 0.070** 1.777 ± 0.076** 

6.97 ± 0.22** 7.67 ± 0.22** 

0.529 ± 0.020 0.528 ± 0.014 

2.25 ± 0.11 2.28 ± 0.04 

0.204 ± 0.013 0.176 ± 0.011 

0.86 ± 0.05 0.76 ± 0.03 

* Significantly different (P<_0.05) from the control group by Williams' or Dunnett's test 

** P _<0.01 

a Organ weights and body weights are given in grams; organ-weight-to-body-weight ratios are given as mg organ weight/g body weight 

(mean ± standard error). 
Organ Weight Analyses 325 

TABLE F4 

Organ Weights and Organ-Weight-to-Body-Weight Ratios for Rats at the 15-Month Interim Evaluation 

in the 2-Year Inhalation Study of Nickel Oxide a 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 

n 5 5 5 5 

Male 

Necropsy body wt 494 ± 10 466 ± 14 465 5:9 475 5:12 

Brain 

Absolute 2.102 5:0.028 2.030 ± 0.016 2.074 ± 0.017 2.062 5:0.018 

Relative 4.26 5:0.08 4.37 5:0,14 4.46 5:0.06 4.35 5:0.13 

R. Kidney 

Absolute 1.662 5:0.026 1.574 ± 0.055 1.586± 0.028 1.554 ± 0.024 

Relative 3.37 ± 0.05 3.37 ± 0.05 3.42 5:0.11 3.28 ± 0.07 

Liver 

Absolute 17.928:5:0.474 16.170 ± 0.764 16.800 ± 0.548 16.534 5:0.774 

Relative 36.27 ± 0.41 34.67 5:1,35 36.11 5:0.85 34.73 ± 0,93 

Lung 

Absolute 2.196 ± 0.038 2.154 ± 0.098 3.304 5: 0.163"* 4.088 ± 0.117"* 

Relative 4.45 5:0.12 4.63 5:0.21 7.13 5: 0.45** 8.63 ± 0.35** 

Spleen 

Absolute 1.054 ± 0.064 0.974 ± 0.072 0.964 5:0,043 1.028 ± 0.040 

Relative 2.13 5:0.10 2.08 ± 0.12 2,07 5:0.09 2.17 ± 0.12 

Thymus 

Absolute 0.249 5:0.011 0.240 ± 0.027 0.228 5:0.019 0.255 ± 0.024 

Relative 0.50 5:0.02 0.52 ± 0.06 0.49 5:0.03 0.54 ± 0.05 

Female 

Necropsy body wt 290 ± 13 309 5:15 284 5:11 295 ± I1 

Brain 

Absolute 1.862 5:0.041 1.878 5:0.030 1.850 5:0.034 1.900 5:0.016 

Relative 6.46 5:0.17 6.12 5:0.20 6.54 5:0.14 6.47 ± 0.23 

R. Kidney 

Absolute 1.052 5:0.036 1.106 ± 0.036 1.062 5:0.046 1.022 ± 0.054 

Relative 3.66 5:0.19 3.61 5:0.20 3.79 5:0.31 3.47 ± 0.15 

Liver 

Absolute 10.194 ± 0.834 10,392 5:0,320 9,896 5:0.154 9,708 ± 0.537 

Relative 35.45 ± 3.37 33.76 5:0.80 35.07 5:1.30 32.90 5:1.45 

Lung 

Absolute 1.558 ± 0.107 1,788 5:0.097 2.406 ± 0.106"* 3.016 ::t= 0.127"* 

Relative 5.39 ± 0.36 5.85 5:0.45 8.51 5: 0.40** 10.29 5: 0.69** 

Spleen 

Absolute 0.556 ± 0,029 0.674 5:0.040 0.526 5:0.022 0.592 5:0.063 

Relative 1.93 ± 0,09 2.20 5:0.15 1.86 ± 0.10 1.99 5:0.16 

Thymus 

Absolute 0.182 5:0.012 0.216 ± 0.010 0.180 5:0,019 0.203 ± 0.033 

Relative 0.63 ± 0.05 0.71 ± 0.05 0.64 5:0.08 0.68 5:0.10 

** Significantly different (P _<0.01) from the control group by Williams' or Dunnett's test 

a Organ weights and body weights are given in grams; organ-weight-to-body-weight ratios are given as mg organ weight/g body weight 

(mean 5: standard error). 
326 Nickel Oxide, NTP TR 451 

TAnLE F5 

Organ Weights and Organ-Weight-to-Body-Weight Ratios for Mice in the 16-Day Inhalation Study of Nickel Oxide a 

0 mg/m 3 1.2 mg/m 3 2.5 mg/m 3 5 mg/m 3 10 mg/m 3 30 mg/m 3 

Male 

n 5 5 5 

Necropsy body wt 23.9 ± 0.8 23.9 ± 0.5 23.8 ± 0.7 

Brain 

Absolute 0.452 ± 0.013 0.442 ± 0.006 0.444 ± 0.005 

Relative 19.04 ± 0.87 18.49 ± 0.39 18.67 ± 0.49 

Heart 

Absolute 0.152 ± 0.010 0.140 5:0.007 0.174 ± 0.017 

Relative 6.38 ± 0.36 5.88 ± 0.39 7.27 ± 0.60 

R. Kidney 

Absolute 0.244 ± 0.005 0.210 ± 0.004* 0.254 ± 0,011 

Relative 10.25 ± 0.24 8.78 ± 0,19"* 10.65 ± 0,31 

Liver 

Absolute 1.380 ± 0.073 1.280 ± 0.049 1.460 ± 0,081 

Relative 57.78 ± 1.89 53.42 ± 1.33 61.09 ± 2.01 

Lung 

Absolute 0.200 ± 0.000 0.160 5:0,024 0.200 ± 0.000 

Relative 8.42 ± 0.30 6.77 ± 1.14 8.42 ± 0.24 

Testes 

Absolute 0.108 ± 0.007 0.100 :t: 0.003 0.104 ± 0.005 

Relative 4.59 ± 0.47 4.19 ± 0.17 4.39 ± 0.31 

Thymus 

Absolute 0.045 ± 0.004 0.050 ± 0.004 0.049 ± 0.008 

Relative 1.92 ± 0.26 2.07 ± 0.15 2.04 ± 0.33 

4 5 5 

23.3 ± 0.5 24.4 ± 0.8 22.3 ± 0,4 

0.430 ± 0.017 0.438 ± 0.007 0.440 ± 0,005 

18.49 ± 0.86 18.03 ± 0.40 19.70 ± 0,18 

0.135 ± 0.019 0.144 ± 0.009 0.146 ± 0.007 

5.76 ± 0.71 5.91 ± 0.35 6.56 ± 0.41 

0.195 ± 0.006** 0,248 ± 0.012 0,214 ± 0.007 

8.38 ± 0.29** 10.17 ± 0.22 9.57 ± 0.19 

1.325 ± 0.075 1.360 ± 0.068 1,160 ± 0.051 

56.75 ± 2.22 55.74 ± 1.37 51.86 ± 1,73 

0.125 ± 0.025** 0.200 ± 0.000 0.200 ± 0.000 

5.37 ± 1.06" 8.24 ± 0.26 8.96 ± 0.15 

0.110 ± 0.009 0.108 ± 0.006 0.110 ± 0.004 

4.73 ± 0.41 4.42 ± 0.12 4.92 ± 0.16 

0.040 ± 0.007 0.051 ± 0.006 0.039 ± 0.004 

1.72 ± 0.31 2.11 5:0.27 1.77 ± 0.20 

Female 

n 5 5 5 5 5 5 

Necropsy body wt 20.2:5:0.5 20.2 ± 0.2 19.4 ± 0.6 20.2 ± 0.3 19.2 ± 0.3 19.3 ± 0.3 

Brain 

Absolute 0.446 ± 0.009 0.432 ± 0.012 0.446 ± 0.005 0.444 ± 0,009 0.422 ± 0.016 0.438 ± 0.006 

Relative 22.05 ± 0.37 21,43 ± 0.55 '23.10 ± 0.94 22.00 ± 0.16 21.98 ± 1.02 22.74 ± 0.42 

Heart 

Absolute 0.114 ± 0.010 0.132 ± 0.009 0.130 ± 0.016 0.128 ± 0.004 0.102 ± 0.005 0.110 ± 0.000 

Relative 5.64 ± 0.49 6.54 ± 0.37 6.66 ± 0.72 6.35 ± 0.20 5.30 ± 0.25 5.71 ± 0.10 

R. Kidney 

Absolute 0.148 ± 0.008 0.158 ± 0.005 0.156 ± 0.011 0.152 ± 0.005 0.148 ± 0.004 0.164 ± 0,007 

Relative 7,31 ± 0.36 7.83 ± 0.19 8.01 ± 0.40 7.54 ± 0.23 7.70 ± 0.21 8.50 ± 0.30* 

Liver 

Absolute 1.160 ± 0,075 1.220 5:0.037 1.040, ± 0.040 i.140 ± 0,024 1.020 ± 0.037 1.080 ± 0.049 

Relative 57.20 ± 2.91 60.48 ± 1.43 53.57 ± 0.94 56.52 ± 1.20 53.06 ± 2.01 55.98 ± 2.16 

Lung 

Absolute 0.160 ± 0.024 0.160 ± 0.024 0.140 ± 0.024 0.180 ± 0.020 0.120 ± 0.020 0.200 ± 0.000 

Relative 7.95 ± 1.27 7.91 ± 1.18 7.17 ± 1.16 8.96 ± 1.05 6.21 ± 0.96 10.39 ± 0.17 

Thymus 

Absolute 0.064 ± 0,004 0.050 ± 0.004 0.059 ± 0.005 0.058 ± 0.002 0.052 ± 0.008 0.050 ± 0.004 

Relative 3.19 ± 0,21 2.51 ± 0.19 3.06 ± 0.27 2.87 ± 0.13 2.70 ± 0.40 2.59 ± 0.20 

* Significantly different (P_<0.05) from the control group by Williams' or Dunnett's test 

** P_<0.01 

a Organ weights and body weights are given in grams; organ-weight-to-body-weight ratios are given as mg organ weight/g body weight 

(mean ± standard error). 
Organ Weight Analyses 327 

TABLE F6 

Organ Weights and Organ-Weight-to-Body-Weight Ratios for Mice in the 13-Week Inhalation Study of Nickel Oxide a 

0 mg/m 3 0.6 mg/m 3 1.2 mg/m 3 2.5 mg/m 3 5 mg/m 3 10 mg/m 3 

Male 

n 10 10 10 10 10 9 

Necropsy body wt 30.9 5:0.5 30.5 5:0.7 29.8 5:0.4 30.1 5:0.8 30.1 5:0.9 29.1 5:0.7 

Brain 

Absolute 0.471 5:0.007 0.462 5:0.005 0.454 5:0.005 0.458 ± 0.005 0.456 5:0.005 0.464 5:0.009 

Relative 15.25 ± 0.25 15.17 ± 0.25 15.28 ± 0.21 15.33 5:0.39 15.24 ± 0.38 15.99 ± 0.36 

Heart 

Absolute 0.163 5:0.007 0.170 5:0.008 0.159 5:0.004 0.144 5:0.007 0.153 5:0.005 0.149 5:0.006 

Relative 5.28 5:0.24 5.59 5:0.32 5.35 5:0.15 4.80 5:0.22 5.10 5:0.18 5.11 5:0.17 

R. Kidney 

Absolute 0.316 5:0.008 0.312 5:0.011 0.309 5:0.010 0.302 5:0.016 0.301 5:0.008 0.276 ± 0.011 

Relative 10.22 5:0.23 10.20 ± 0.23 10.39 5:0.34 I0.00 5:0.32 10.02 5:0.24 9.45 ± 0.32 

Liver 

Absolute 1.710 5:0.055 1.680 5:0.071 1.550 5:0.050 1.610 ± 0.098 1.520 5:0.063 1.444 5: 0.065* 

Relative 55.20 ± 1.17 54.82 ± 1.33 52.06 ± 1.33 53.10 5:2.17 50.51 ± 1.64" 49.42 5: 1.29" 

Lung 

Absolute 0.214 5:0.009 0.215 5:0.011 0.206 5:0.012 0.213 ± 0.009 0.243 ± 0.010 0.288 ± 0.019"* 

Relative 6.96 5:0.33 7.10 5:0.48 6.93 ± 0.42 7.12 ± 0.29 8.06 ± 0.27 9.94 5: 0.68** 

R. Testis 

Absolute 0.121 ± 0.005 0.118 ± 0.004 0.115 ± 0.003 0.112 5:0.004 0.123 5:0.004 0.106 ± 0.009 

Relative 3.92 ± 0.16 3.87 ± 0.12 3.87 5:0.11 3.75 ± 0.17 ' 4.09 ± 0.08 3.61 ± 0.31 

Thymus 

Absolute 0.034 5:0.002 0.030 ± 0.003 0.031 5:0.002 0.031 ± 0.003 0.032 5:0.001 0.032 5:0.002 

Relative 1.10 5:0.07 0.99 ± 0.10 1.03 ± 0.06 1.00 5:0.08 1.06 5:0.04 1.09 ± 0.05 

Female 

n 9 10 7 10 10 9 

Necropsy body wt 27.5 5:0.6 26.6 5:0.7 27.1 5:1.0 27.0 5:0.8 25.7 5:0.7 26.1 5:0.5 

Brain 

Absolute 0.476 ± 0.004 0.475 5:0.006 0.467 ± 0.006 0.471 5:0.022 0.464 5:0.005 0.470 5:0.006 

Relative 17.34 5:0.41 17.97 5:0.47 17.34 5:0.49 17.51 5:0.78 18.15 5:0.39 18.05 5:0.22 

Heart 

Absolute 0.152 5:0.005 0.138 5:0.005 0.143 5:0.004 0.142 5:0.005 0.139 5:0.006 0.144 5:0.006 

Relative 5.55 5:0.23 5.19 5:0.13 5.31 5:0.20 5.27 5:0.13 5.41 5:0.18 5.55 5:0.25 

R. Kidney 

Absolute 0.220 ± 0.010 0,223 ± 0.025 b 0.213 ± 0.008 c 0.210 5:0.007 0.206 5:0.006 0.204 5:0.005 d 

Relative 8.01 5:0.35 8.43 ± 0.78 b 7.90 5:0.13 c 7.79 5:0.13 8.04 5:0.20 7.74 5:0.14 d 

Liver 

Absolute 1.544 ± 0.067 1.540 5:0.052 1.429 5:0.071 1.530 ± 0.052 1.400 ± 0.042 1.433 5:0.053 

Relative 56.00 5:1.78 57.92 5:1.04 52.72 5:1.62 56.80 5:1.12 54.52 5:0.91 54.91 5:1.30 

Lung 

Absolute 0.195 ± 0.012 0.195 5:0.018 0.192 5:0.008 0.213 5:0.008 0.223 ± 0.009 0.271 5: 0.007** 

Relative 7.11 ± 0.44 7.26 5:0.48 7.08 ± 0.26 7.91 5:0.22 8.69 ± 0.31"* 10.40 5: 0.17"* 

Thymus 

Absolute 0.046 5:0.003 0.045 5:0.004 0.046 5:0.003 0.043 ± 0.003 0.040 5:0.002 0.039 ± 0.003 

Relative 1.66 5:0.10 1.67 5:0.13 1.71 5:0.12 1.62 ± 0.10 1.57 5:0.06 1.48 5:0.10 

* Significantly different (P_<0.05) from the control group by Williams' or Dunnett's test 

** P_<0.01 

a Organ weights and body weights are given in grams; organ-weight-to-body-weight ratios are given as mg organ weight/g body weight 

(mean 5: standard error). 

b n=9; c n=6; d n=8 
328 Nickel Oxide, NTP TR 451 

TABLE F7 

Organ Weights and Organ-Weight-to-Body-Weight Ratios for Mice at the 72Month Interim Evaluation 

in the 2-Year Inhalation Study of Nickel Oxide a 

0 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 5 mg/m 3 

n 5 5 5 5 

Male 

Necropsy body wt 35.8 ± 0.7 34.6 ± 0.8 36.2 ± 1.5 34.7 ± 1.1 

Brain 

Absolute 0.460 ± 0,008 0,470 ± 0.009 0.458 ± 0.007 0.458 ± 0.011 

Relative 12.86 ± 0.06 13.60 ± 0.34 12.72 ± 0.39 13.24 ± 0.31 

R. Kidney 

Absolute 0.378 5:0.012 0,390 ± 0.016 0.410 ± 0.010 0.406 ± 0.012 

Relative 10.57 ± 0.31 11.29 ± 0.53 11.40 ± 0.47 11.76 ± 0.49 

Liver 

Absolute 1.800 ± 0.046 1.606 ± 0.027* 1.706 ± 0.072 1,810 5:0.036 

Relative 50.30 :t: 0.73 46.48 ::1: 1.25" 47.16 ± 0.69 52.32 ± 0.83 

Lung 

Absolute 0.192 ± 0.009 0.208 ± 0.004 0.240 ± 0.010"* 0.238 ± 0.006** 

Relative 5.37 ± 0.24 6.02 ± 0.20* 6.64 ± 0.11"* 6.88 ± 0.16"* 

Spleen 

Absolute 0,076 ± 0.004 0.078 ± 0,007 0.082 ± 0.004 0.078 ± 0.006 

Relative 2.13 ± 0.12 2.26 ± 0,20 2.27 ± 0.09 2.25 ::t: 0.14 

R. Testis 

Absolute 0.122 ± 0.006 0.120 ± 0,003 0.126 ± 0.002 0.126 ± 0.004 

Relative 3.42 ± 0.21 3.47 ± 0,11 3.50 ± 0.13 3.64 ± 0.11 

Thymus 

Absolute 0.032 ± 0.002 0.043 ± 0,008 0.034 ± 0.005 0.033 ± 0,002 

Relative 0.90 ± 0.07 1.23 ± 0.23 0.93 ± 0.12 0.95 ± 0.07 

Female 

Necropsy body wt 28.5 ± 1.0 28.5 ± I.I 28.6 ± 1.4 30.4 ± 0.8 

Brain 

Absolute 0.482 ± 0.004 0.470 5:0.008 0.474 ± 0.010 0,466 ± 0.010 

Relative 17.01 ± 0.52 16.58 ± 0.49 16.69 ± 0.79 15.37 ± 0,60 

R. Kidney 

Absolute 0.244 ± 0.007 0.250 ± 0.004 0.246 ± 0,007 0.266 ± 0,005* 

Relative 8.59 ± 0.14 8.82 ± 0.24 8.63 ± 0.23 8.77 ± 0,33 

Liver 

Absolute 1.512 ± 0.037 1.554 ± 0.053 1.416 ± 0.040 1.598 ± 0,038 

Relative 53.30 ± 1.71 54.73 ± 1.70 49.69 ± 1.32 52.61 ± 1,38 

Lung 

Absolute 0.178 ± 0.010 0.206 ± 0.011 0.228 ± 0.019 0.232 ± 0.022 

Relative 6.25 ± 0.24 7.22 ± 0.12 7.94 ± 0.41" 7.62 ± 0.67* 

Spleen 

Absolute 0.100 ± 0.005 0.124 ± 0.022 0.098 ± 0.004 0.116:5:0.009 

Relative 3.54 ± 0.24 4.44 ± 0.93 3.45 ± 0.18 3.82 ± 0.32 

Thymus 

Absolute 0.044 ± 0,005 0.050 ± 0.004 0.035:5:0.002 0.040 ± 0.005 

Relative 1.55 ± 0.19 1.77 ± 0.19 1.23 ± 0.10 1.31 ± 0.13 

* Significantly different (P <_0.05) from the control group by Williams' or Dunnett's test 

** P_<0.01 

a Organ weights and body weights are given in grams; organ-weight-to-body-weight ratios are given as mg organ weight/g body weight 

(mean ± standard error). 
Organ Weight Analyses 329 

TABLE F8 

Organ Weights and Organ-Weight-to-Body-Weight Ratios for Mice at the 15-Month Interim Evaluation 

in the 2-Year Inhalation Study of Nickel Oxide a 

0 mg/m 3 1.25 mg/m 3 2.5 mg/m ~ 5 mg/m ~ 

n 5 5 5 5 

Male 

Necropsy body wt 37.9 2:1.1 39.0 ± 1.5 41.3 ± 1.7 41.1 ± 1.8 

Brain 

Absolute 0.470 ± 0.007 0.472 2:0.007 

Relative 12.44 ± 0.36 12.16 ::t: 0.46 

R. Kidney 

Absolute 0.430 ± 0.029 0.410 2:0.013 

Relative 11.36 2:0.77 10.55 ± 0.40 

Liver 

Absolute 1.848 ± 0.083 b 2.114 ± 0.128 

Relative 47.61 5:2.43 b 54.47 2:3.90 

Lung 

Absolute 0.234 2:0.017 0.246 2:0.021 

Relative 6.24 ± 0.65 6.28 ± 0.34 

Spleen 

Absolute 0.130 ± 0.041 0.078 ± 0.008 

Relative 3.57 ± 1.26 2.00 2:0.20 

Thymus 

Absolute 0.054 2:0.007 0.047 2:0.005 

Relative 1.44 5:0.23 1.19 2:0.09 

0.482 ± 0.004 0.482 ± 0.004 

11.75 2:0.43 11.83 ± 0.55 

0.436. 2:0.024 0.440 ± 0.008 

10.61 ± 0.64 10.78 2:0.43 

2.236 2:0.307 1.998 2:0.079 

54.41 ± 7.79 48.72 ± 0.64 

0.306 5: 0.020* 0.382 2: 0.019"* 

7.44 2:0.48 9.44 ± 0.86** 

0.096 2:0.019 0.074 2:0.006 

2.34 2:0.48 1.82 2:0.18 

0.046 ± 0.008 0.049 2:0.007 

1.14 2:0.23 1.19 2:0.17 

Female 

Necropsy body wt 39.5 2:3.2 37.1 2:1.6 38.3 2:1.9 34.4 ± 2.1 

Brain 

Absolute 0.498 ± 0.005 0.496 ± 0.004 0.488 ± 0.004 0.500 ± 0.014 

Relative 12.89 ± 0.90 13.47 ± 0.57 12.85 ± 0.62 14.70 ± 0.75 

R. Kidney 

Absolute 0.296 2:0.014 0.306 5:0.009 0.308 ± 0.023 0.272 ± 0.007 

Relative 7.71 ± 0.78 8.29 ± 0.29 8.14 ± 0.80 8.05 ± 0.64 

Liver 

Absolute 1.898 ± 0.093 1.810 ± 0.030 1.896 ± 0.090 1.770 5:0.056 

Relative 48.99 2:3.84 49.05 5:1.72 49.79 ± 2.81 52.07 2:2.93 

Lung 

Absolute 0.248 ± 0.010 0.264 ± 0.010 0.294 ± 0.018 0.340 ± 0.026** 

Relative 6.37 ± 0.30 7.12 ± 0.04 7.70 ± 0.43 10.07 ± 1.02"* 

Spleen 

Absolute 0.124 ± 0.018 0.130 2:0.006 b 0.130 ± 0.011 0.118 ± 0.011 

Relative 3.27 ± 0.63 3.46 ± 0.27 b 3.42 2:0.34 3.47 ± 0.39 

Thymus 

Absolute 0.048 ± 0.004 0.056 2:0.005 0.066 ± 0.007 0.052 ± 0.006 

Relative 1.23 2:0.06 1.52 ± 0.15 1.73 2:0.19 1.55 ± 0.25 

* Significantly different (P_~O.05) from the control group by Williams' or Dunnett's test 

** P_<0.01 

a Organ weights and body weights are given in grams; organ-weight-to-body-weight ratios are given as mg organ weight/g body weight 

(mean 2: standard error). 

b n=4 
330 Nickel Oxide, NTP TR 451 
331 

APPENDIX G 

HEMATOLOGY RESULTS 

TABLE G1 

TABLE G2 

TABLE G3 

TABLE G4 

Hematology Data for Rats in the 13-Week Inhalation Study 

of Nickd Oxide .............................................. 332 

Hematology Data for Rats at the 15-Month Interim Evaluation 

in the 2-Year Inhalation Study of Nickel Oxide .......................... 334 

Hematology Data for Mice in the 13-Week Inhalation Study 

of Nickel Oxide .............................................. 335 

Hematology Data for Mice at the 15-Month Interim Evaluation 

in the 2-Year Inhalation Study of Nickel Oxide .......................... 337 
332 Nickel Oxide, NTP TR 451 

TABLE G1 

Hematology Data for Rats in the 13-Week Inhalation Study of Nickel Oxide a 

0 mg/m 3 0.6 mg/ra 3 1.2 mg/m 3 2.5 rag/m 3 5 mg/m 3 10 mg/m 3 

Male 

n 9 10 10 9 10 10 

Hematocrit (%) 

43.6 ± 0.5 

Hemoglobin (g/dL) 

15.3 5:0.2 

Erythrocytes (106/#L) 

8.33 ± 0.08 

Mean cell volume (fL) 

53.0 5:0.2 52.2 ± 0.2 

Mean cell hemoglobin concentration (g/dL) 

35.1 5:0.2 35.6 ± 0.2 

Reticulocytes (106//zL) 

0.5 ±0.1 

Leukocytes (103/~L) 

2.22 ± 0.24 

Segmented neutrophils (103//~L) 

0.62 ± 0.07 

Lymphocytes (103/ttL) 

1.55 5:0.19 

Monocytes (103//zL) 

0.04 ± 0.02 

Eosinophils (103//~L) 

0.02 ± 0.01 

Nucleated erythrocytes (103/~L) 

0.03 5:0.01 

43.3 5:0.2 

15.4 ± 0.1 

8.42 5:0.03 

0.6 ±0.1 

2.48 ± 0.23 

0.71 5:0.09 

1.71 ± 0.15 

0.05 ::t: 0.01 

0.02 ± 0.01 

0.05 ± 0.02 

44.2 ± 0.5 43.8 ± 0.8 43.8 ± 0.7 46.4 ± 0.5** 

15.5 ± 0.2 15.7 ± 0.3 15.6 ± 0.2 . 16.6 ± 0.2** 

8.46 5:0.14 8.51 ± 0.15 8.55 ± 0.12 9.02 ± 0.11"* 

53.0 ± 0.6 52.2 ± 0.2 51.9 ± 0.3** 52.2 ± 0.3 

35.1 ± 0.2 35.9 5: 0.1"* 35.7 5:0.1 35.7 ± 0.2 

0.9 ± 0.1" 0.7 ± 0.1 0.6 ± 0.1 0.5 ± 0.1 

3.56 ± 0.40* 2.67 ± 0.30 3.00 ± 0.37 3.34 ± 0.31" 

1.01 ± 0.08** 1.06 ± 0.15" 1.14 ± 0.18" 1.26 ± 0.18"* 

2.48 ± 0.31 1.56 ± 0.16 1.79 5:0.24 1.98 5:0.23 

0.06 ± 0.03 0.03 ± 0.01 0.04 5:0.02 0.08 5:0.02 

0.02 ± 0.01 0.02 5:0.01 0.02 ± 0.01 0.02 5:0.01 

0.13 ± 0.04 0.13 ± 0.04 0.20 5: 0.05* 0.12 5:0.04 
Hematology Results 333 

TABLE G1 

Hematology Data for Rats in the 13-Week Inhalation Study of Nickel Oxide (continued) 

0 mg/m 3 0.6 mg/m 3 1.2 mg/m 3 2.5 mg/m 3 5 mg/m 3 10 mg/m 3 

Female 

n 10 10 10 10 10 10 

Hematocrit (%) 

40.8 5:1.0 43.5 ± 1.0 42.7 5: 0.3* 42.5 5: 1.0"* 43.3 5: 0.2** 44.0 5: 0.5** 

Hemoglobin (g/dL) 

14.4 5:0.3 15.6 5: 0.4** 15.3 :t: 0.1"* 15.3 5: 0.4** 15.7 5: 0.1"* 15.9 5: 0.1"* 

Erythrocytes (106//xL) 

7.2 5:0.2 7.8 5:0.2 7.7 5:0.1 7.7 5: 0.2* 7.9 5: 0.0"* 8.0 5: 0.1"* 

• Mean cell volume (fL) 

57.3 5:0.5 56.7 5:0.2 56.2 5: 0.2* 56.3 5: 0.2* 56.1 5: 0.3* 56.0 5: 0.3* 

Mean cell hemoglobin concentration (g/dL) 

35.3 5:0.1 35.9 5: 0.1"* 35.9 5: 0.1"* 36.0 5: 0.1"* 36.2 5: 0.3** 36.2 ::k 0.2** 

Reticulocytes (106/~L) 

0.4 5:0.0 0.3 5:0.0 0.4 5:0.0 0.5 5:0.1 0.5 ± 0.1 0.5 5:0.1 

Leukocytes (103/~L) 

2.04 5:0.18 2.40 5:0.15 2.64 5: 0.15" 3.50 5: 0.18"* 2.89 5: 0.24** 3.55 5: 0.21"* 

Segmented neutrophils (103/~L) 

0.45 5:0.06 0.73 5: 0.08* 0.79 5: 0.07** 0.91 5: 0.I0"* 0.74 5: 0.09** 0.92 5: 0.09** 

Lymphocytes (103/~L) 

1.55 5:0.16 1.63 ± 0.I1 1.80 5:0.15 2.48 ± 0.13"* 2.09 5: 0.17"* 2.53 5: 0.17"* 

Monocytes (103/~L) 

0.02 5:0.01 0.03 5:0.01 0.02 5:0.01 0.06 5: 0.01"* 0.05 5: 0.01" 0.09 5: 0.02** 

Eosinophils (103//~L) 

0.02 ± 0.01 0.01 5:0.01 0.03 5:0.01 0.04 5:0.01 0.02 5:0.01 0.01 5:0.01 

Nucldated erythrocytes (103/~L) 

0.02 5:0.01 0.11 5: 0.03* 0.18 5: 0.03** 0.12 5: 0.03** 0.18 ± 0.03** 0.23 5: 0.05** 

* Significantly different (P <_0.05) from the control group by Dunn's or Shirley's test 

** P <-0.01 

a Mean 5: standard error 
334 Nickel Oxide, NTP TR 451 

TABLE G2 

Hematology Data for Rats at the 15-Month Interim Evaluation in the 2-Year Inhalation Study 

of Nickel Oxide a 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m ~ 2.5 mg/m J 

n 5 5 5 5 

Male 

Hemamcrit (%) 48.3 ± 0.4 48.4 5:1.5 49.1 ± 0.8 47.1 ± 4.7 

Hemoglobin (g/dL) 16.3 ± 0.2 16.2 ± 0.5 16.6 ± 0.2 15.9 ± 1.7 

Erythrocytes (106/tzL) 8.75 5:0.07 8.66 ± 0.26 8.92 ± 0.11 8.68 ± 0.73 

Mean cell volume (fL) 54.8 5:0.4 55.2 5:0.7 54.6 ± 0.2 53.6 ± 1.2 

Mean cell hemoglobin (pg) 18.6 5:0.1 18.7 ± 0.3 18.6 ± 0.1 18.2 5:0.5 

Mean cell hemoglobin 

concentration (g/dL) 33.7 ± 0.4 33.4 ± 0.1 33.7 5:0.3 33.7 5:0.4 

Reticulocytes (106//~L) 0.3 ± 0.0 0.1 ± 0.0" 0.2 ± 0.0" 0.3 ± 0.1 

Leukocytes (103//~L) 5.68 ::t: 0.54 5.60 ± 0.26 6.08 ± 0.48 7.44 ± 0.68 

Segmented neutrophils (103//~L) 1.84 5:0.22 1.64 5:0.32 2.00 ± 0.21 2.54 ± 0.45 

Lymphocytes (103/#L) 3.46 ± 0.27 3.56 ± 0.25 3.48 ± 0.27 4.54 ± 0.48 

Monocytes (103/~L) 0.38 ± 0.08 0.36 ± 0.02 0.50 5:0.16 0.34 ± 0.04 

Eosinophils (103/t~L) 0.06 ± 0.02 0.06 ± 0.04 0.06 ± 0.02 0.06 ± 0.02 

Nucleated erythrocytes (103/~L) 0.00 ± 0.00 0.02 ± 0.01 0.02 5:0.01 0.04 ± 0.04 

Female 

Hematocrit (%) 47.4 ± 1.4 47.2 ± 0.7 47.8 ± 0.9 49.4 ± 0.9 

Hemoglobin (g/dL) 16.4 ± 0.2 16.2 5:0.3 16.4 ± 0,3 17.1 ± 0.2 

Elrythrocytes (106/~L) 8.11 ± 0.18 7.83 5:0.15 7.96 ± 0.17 8.22 ± 0.16 

Mean cell volume (fL) 58.0:5:0.3 60.0 5: 0,5* 59.6 5:0,6 59.6 5:0.5 

Mean cell hemoglobin (pg) 20.3 5:0.3 20.7 ± 0.2 20.7 ± 0.1 20.8 ± 0.2 

Mean cell hemoglobin 

concentration (g/dL) 34.7 ± 0.8 34.4 5:0,3 34.4 ± 0.3 34.6 ± 0.3 

Reticulocytes (106/t~L) 0.1 ± 0.0 0.1 ± 0.0 0.1 5:0.0 0,1 ± 0.0 

Leukocytes (103/iLL) 4.84 ± 0.29 4.92 ± 0.39 4.20 5:0.33 4.60 5:0.32 

Segmented neutrophils (103/~L) 1.22 ± 0.21 1.06 5:0.14 1.12 ± 0.10 1.14 5:0.20 

Lymphocytes (103//~L) 3.26 ± 0.28 3.68 ± 0.31 2.72 ± 0.26 3.20 ± 0.22 

Monocytes (103//~L) 0.30 5:0.03 0.16 ± 0.04 0.28 ± 0.07 0.24 ± 0.08 

Eosinophils (103/#L) 0.08 5:0.04 0.04 5:0.02 0.08 ± 0.04 0.00 5:0.00 

Nucleated erythrocytes (103/~L) 0.02 ± 0.02 0.00 ± 0.00 0.00 ± 0.00 0.03 ± 0.02 

* Significantly different (P~0.05) from the control group by Dunn's or Shirley's test 

a Mean ± standard error 
Hematology Results 335 

TABLE G3 

Hematology Data for Mice in the 13-Week Inhalation Study of Nickel Oxide a 

0 mg/m 3 0.6 mg/m 3 1.2 mg/m 3 2.5 mg/m 3 5 mg/m 3 10 mg/m 3 

Male 

n 5 5 5 5 5 5 

Hematocrit (%) 

44.4 ± 2.0 

Hemoglobin (g/dL) 

14.6 5:0.3 

Erythrocytes (106/~L) 

8,70 5:0.31 

Mean cell volume (fL) 

51.8 5:0.7 51.6 5:0.9 

Mean cell hemoglobin concentration (g/dL) 

33.0 5:0.9 33.9 5:0.9 

Reticulocytes (106/~L) 

0.4 5:0.1 

Leukocytes (103Iv.L) 

1.24 5:0.53 

Segmented neutrophils (103//~L) 

0.81 ± 0.41 

Lymphocytes (103/~L) 

0.41 5:0.14 

Monocytes (103/~L) 

0.02::t: 0.01 

Eosinophils (103/#L) 

0.01 ,5:0.01 

Nucleated erythrocytes (103/~L) 

0.01 ± 0.01 

42.0 5:0.8 

14.3 ± 0.4 

8,31 5:0.15 

0.7 ± 0.3 

1.50 5:0.60 

0.62 5:0.24 

0.87 ± 0.43 

0.00 5:0.00 

0.01 5:0.01 

0.06 ± 0.04 

43'.3 :t: 1.3 42.5 5:0.6 44.3:5:0.7 42.4 ::k 1.5 

14.9 5:0.5 14.8 5:0.2 15.1 5:0.3 14.5 5:0.5 

8.46 + 0.31 7.96 5:0.23 8.65 + 0.08 8.37 + 0.25 

52.0 + 0.5 54.2 + 1.4 52,0 5:0.3 51.2 4- 0.5 

34.3 5:0.3 34.8 + 0.2* 34,2 5:0.1 34.3 5:0.3 

0.5 ± 0.1 0,5 5:0.2 0.4 5:0.0 0.5 5:0.1 

1.60 ± 0.46 1,34 ± 0.19 0.98 5:0.21 1.76 ::k 0.30 

0.50 5:0.14 0.59 ± 0.10 0.32 ± 0.06 0.48 5:0.12 

1.07 5:0.32 0.74 ::t: 0.15 0.64 5:0.17 1.24 5: 0.24* 

0.01 5:0.01 0.01 :t: 0.00 0.02 5:0.01 0.03 5:0.01 

0.02 5:0.01 0.00 5:0.00 0.00 ± 0.00 0.01 5:0.01 

0.09 ± 0.03 0.03 ± 0.02 0.07 ± 0.02 0.09 5:0.03 
336 Nickel Oxide, NTP TR 451 

TABLE G3 

Hematology Data for Mice in the 13-Week Inhalation Study of Nickel Oxide (continued) 

0 mg/m 3 0.6 mg/m 3 1.2 mg/m 3 2.5 mg/m 3 5 mg/m 3 10 mg/m 3 

Female 

n 4 5 2 5 5 5 

Hematocrit (%) 

40.7 ± 0.5 

Hemoglobin (g/dL) 

14.2 ± 0.1 

Etythrocytes (106/t~L) 

8.10 ± 0.06 

Mean cell volume (fL) 

51.0 ± 0.4 51.2 ± 0.2 

Mean cell hemoglobin concentration (g/dL) 

35.0 ± 0.2 35.5 ± 0.3 

Reticulocytes (106/~L) 

0.5 ±0.1 

Leukocytes (103/~L) 

1.03 ± 0.09 

Segmented neutrophils (103/~L) 

0.39 ± 0.09 

Lymphocytes (103/~L) 

0.62 ± 0.06 

Monocytes (103/#L) 

0.02 ± 0.01 

Eosinophils (103/~L) 

0.00 ± 0.00 

Nucleated e~ythrocytes (103/~L) 

0.01 ± 0.01 

39.8 ± 0.9 

14.1 ± 0.4 

7.91 ± 0.17 

0.5 ±0.1 

0.92 ± 0.19 

0.37 ± 0.11 

0.52 ± 0.I0 

0.02 ± 0.01 

0.00 ± 0.00 

0,01 ± 0.01 

42.5 ± 0.8 41.8 ± 0.6 42.4 ± 0,3* 42.5 ± 0.3* 

14.9 ::1:0.1 14.7 ± 0.2 15.0 ± 0.1"* 14.7 ± 0.1 

8.38 ± 0.07 8.30 ::1:0.11 8.48 ± 0.08* 8.50 ± 0.07* 

51.5 ± 1.5 51.0 ± 0.0 50.6 ± 0.2 50.4 5:0.4 

35.0 ± 0.7 35.2 ± 0.1 35.3 ± 0.2 34.7 ::1:0.1 

1.2 ± 0.2 0.6 ± 0.1 0.5 ± 0.1 0.7 ± 0.2 

3.10 ± 0.00 0.68 ± 0.12 1.34 ± 0.11 1.18 ± 0.42 

1.01 ± 0.14 0.23 ± 0.04 0.42 ± 0.10 0.43 ± 0.15 

2.06 ± 0.11 0.42 ± 0.10 0.92 ± 0,10 0.73 ± 0.28 

0.03 ± 0.03 0.01 ± 0.01 0.00 ± 0.00 0.01 ± 0.01 

0.00 ± 0.00 0.02 ± 0.01 0.00 ± 0.00 0.01 ± 0.01 

0.19 ± 0.09 0.01 ± 0.00 0.06 ± 0.01 0.02 ± 0.01 

* Significantly different (P_<0.05) from the control group by Dunn's or Shirley's test 

** P_<0.01 

a Mean ± standard error 
Hematology Results 337 

TABLE G4 

Hematology Data for Mice at the 15-Month Interim Evaluation in the 2-Year Inhalation Study 

of Nickel Oxide a 

0 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 5 mg/m ~ 

Male 

n 5 5 5 5 

Hematocrit (%) 51.6 ± 5.5 48.0 ± 1.3 50.6 5:4.5 46.5 ± 0.5 

Hemoglobin (g/dL) 17.0 ± 1.7 15.9 5:0.4 16.9 5:1.6 15.4 ± 0.1 

Erythrocytes (106/#L) 10.40 5:1.36 9.41 5:0.34 10.03 ± 0.91 9.08 5:0.14 

Mean cell volume (fL) 49.8 ± 1.0 50.8 ± 0.7 50.0 ± 0.0 51.0 5:0.6 

Mean cell hemoglobin (pg) 16.6 5:0.4 16.9 ± 0.3 16.8 5:0.2 17.0 5:0.1 

Mean cell hemoglobin 

concentration (g/dL) 33.0 5:0.3 33.2 ± 0.1 33.3 5:0.4 33.1 5:0.2 

Reticulocytes (106/~L) 0.3 ± 0.0 b 0.1 ± 0.0 0.2 ± 0.0 b 0.2 ± 0.0 

Leukocytes (103/#L) 3.44 ± 0.51 4.08 ± 0.60 2.28 5:0.16 4.08 ± 0.19 

Segmented neutrophi|s (103/#L) 1.16 5:0.31 1.72 ± 0.25 0.84 5:0.14 1.50 5:0.23 

Lymphocytes (103/#L) 2.08 ± 0.22 2.20 5:0.41 1.36 ± 0.16 2.34 5:0.27 

Monocytcs (103//xL) 0.18 ± 0.13 0.14 ± 0.07 0.04 5:0.02 0.16 5:0.07 

Eosinophils (103/#L) 0.04 5:0.02 0.00 5:0.00 0.06 5:0.02 0.08 5:0.02 

Nucleated erythrocytes (103/t~L) 0.00 5:0,00 0,0l ± 0.01 0,00 5:0.00 0,01 ± 0,01 

Female 

4 5 4 5 

Hematocrit (%) 45.5 5:0.5 46.2 ± 0.5 46.7 5:~0.4 47.2 5:0.9 

Hembglobin (g/dL) 15.5 ± 0.1 15.6 5:0.2 15.7 ± 0.1 16.0 5:0.3 

Erythrocyt~s (106/#L) 9.17 5:0.12 9.23 5:0.12 9.44 5:0.03 9.40 ± 0.16 

Mean cell volume (fL) 49.3 5:0.5 49.6 5:0.2 49.0 5:0.4 49,8 5:0.5 

Mean cell hemoglobin (pg) 16.9 ± 0.2 17.0 5:0.2 16.6 5:0.2 17.0 5:0.1 

Mean cell hemoglobin 

concentration (g/dL) 34.1 5:0.1 33.8 ± 0.2 33.6 5:0.1 33.9 5:0.1 

Reticulocytes (106/~L) 0,1 5:0.0 0.1 5:0.0 0.1 5:0.0 0.1 5:0.0 

Leukocytes (103/#L) 2.45 5:0.33 2.65 5:0.21 b 2.70 5:0.26 2.36 5:0.29 

Segmented neutr,o3P, hils (103/#L) 1.03 5:0.40 0.90 5:0.19 b 1.15 ± 0.05 0.70 5:0.13 

Lymphocytes (10//zL) 1.33 5:0.23 1.68 ± 0.10 b 1.38 5:0.18 1.54 5:0.19 

Monocytes (103/~L) 0.08 ± 0.03 0.08 ± 0.03 b 0.08 ± 0.03 0.08 5:0.02 

Eosinophils (103/~tL) 0.03 ± 0.03 0.00 ± 0.00 b 0.05 5:0.03 0.02 ± 0.02 

Nucleated e~throcytes (103/~L) 0.00 5:0.00 0.00 5:0.00 0.00 5:0.00 0.01 5:0,01 

a Mean 5: standard error 

b n=4 
Nickel Oxide, NTP TR 451 

338 
339 

APPENDIX H 

TISSUE BURDEN IN RATS 

TABLE H1 

TABLE H2 

TABLE H3 

TABLE H4 

Lung Weight and Lung Burden in Rats in the 16-Day Inhalation Study 

of Nickel Oxide .............................................. 340 

Kidney Weight and Kidney Burden in Rats in the 16-Day Inhalation Study 

of Nickel Oxide .............................................. 340 

Lung Weight and Lung Burden in Male Rats in the 13-Week Inhalation Study 

of Nickel Oxide .............................................. 341 

Lung Weight and Lung Burden in Rats in the 2-Year Inhalation Study 

of Nickel Oxide .............................................. 342 
340 Nickel Oxide, NTP TR 451 

TABLE H1 

Lung Weight and Lung Burden in Rats in the 16-Day Inhalation Study of Nickel Oxide a 

0 mg/m 3 1.2 mg/m 3 5 mg/m 3 10 mg/m 3 

n 5 5 5 5 

Male 

Absolute lung wt (g) 0.856 ± 0.047 0.870 5:0.046 0.822 ± 0.041 1.068 ± 0.056* 

/~g Ni/lung _b 36 ± 1.3"* 88 ± 4.8** 284 ± 9.7** 

/.tg Ni/g lung -- 42 ± 2.8** 108 ± 4.3** 267 ± 12.3"* 

ttg Ni/g control lung -- 42 ± 1.6"* 103 ± 5.6** 331 ± 11.4"* 

Female 

Absolute lung wt (g) 0.739 ± 0.028 0.704 ± 0.017 0.731 ± 0.040 0.861 ± 0.025* 

~g Ni/lung -- 38 ± 4.8** 88 ± 3.3** 293 ± 13.4"* 

#g Ni/g lung -- 54 5: 5.7** 122 ± 10.3"* 340 5: 10.4"* 

/~g Ni/g control lung -- 52 ± 6.5** 119 ± 4.5** 396 ± 18.2"* 

* Significantly different (P_<0.05) from the control group by Dunnett's test (lung weight) or Shirley's test (lung burden parameters) 

** P-<0.01 

a Mean ± standard error 

b Results were below 0.182/~g Ni (the limit of detection), or below the level of quantitation. 

TABLE H2 

Kidney Weight and Kidney Burden in Rats in the 16-Day Inhalation Study of Nickel Oxide a 

0 mg/m 3 10 mg/m 3 

n 5 5 

Male 

Absolute kidney wt (g) 

pg Ni/kidney 

btg Ni/g kidney 

1.76 ± 0.05 1.71 ± 0.02 

b 

-- -- 

__ -- 

Female 

Absolute kidney wt (g) 1.25 ± 0.01 1.71 ± 0.02** 

#g Ni/kidney -- -- 

/~g Ni/g kidney -- -- 

** Significantly different (P -<0.01) from the control group by Williams' or Dunnett's test (kidney weight) or Shirley's test (kidney burden 

parameters) 

a Mean ± standard error 

b Results were below 0.182 ~g Ni (the limit of detection), or below the level of quantitation. 
Tissue Burden in Rats 341 

TABLE H3 

Lung Weight and Lung Burden in Male Rats in the 13-Week Inhalation Study of Nickel Oxide a 

0 mg/m 3 0.6 mg/m 3 2.5 mg/m 3 10 mg/m 3 

n 6 6 6 6 

4 weeks 

/zg Ni/g lung _b 33 ± 2.3** 110 5: 6.6** 263 ± 18.5"* 

9 weeks 

~g Ni/g lung -- 53 5: 6.8** 143 5: 27.9** 400 ± 31.2"* 

13 weeks 

Absolute lung wt (g) 0.954 ± 0.043 1.082 5:0.028 1.534 ± 0.032** 2.108 ± 0.097** 

ttg Ni/lung -- 86 5: 6.0** 27~ 5: 34.6** 1,092 ± 63.1"* 

#g Ni/g lung -- 80 5: 5.5** 181 ± 25.6** 524 ± 38.2** 

~g Ni/g control lung -- 91 ± 6.3** 289 ± 36.3** 1,146 ± 66.2** 

** Significantly different (P_<0.01) from the control group by Williams' test (lung weight) or Shirley's test (lung burden parameters) 

a Mean ± standard error 

b Results were below 0.301 ~g Ni (the limit of detection), or below the level of quantitation. 
342 Nickel Oxide, NTP TR 451 

TABLE H4 

Lung Weight and Lung Burden in Rats in the 2-Year Inhalation Study of Nickel Oxide a 

0 mg/m 3 0.62 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 

Male 

n 6 7 7 7 

7-Month interim evaluation 

Absolute lung wt (g) 1.72 ± 0.07 1.85 ± 0.07 2.43 ± 0.11"* 2.59 ± 0.06** 

/zg Ni/lung _b 326 ± 29.6** 930 ± 21.3"* 1,817 ± 68.6** 

~g Ni/g lung -- 175 ± 10.6"* 388 ± 18.7"* 701 ± 24.1"* 

~g Ni/g control lung -- 189:5: 17.2"* 541 ± 12.4"* 1,057 ± 39.9** 

n 5 5 5 5 

15-Month interim evaluation 

Absolute lung wt (g) 2.20 ± 0.04 2.15 ± 0.10 3.30 ± 0.16"* 4.09 ± 0.12"* 

#g Ni/lung -- 696 ± 41.6"* 2,439 ± 71.9"* 4,573 ± 485.4** 

#g Ni/g lung -- 328 ± 30.2** 746 ± 46.6** 1,116 ± 108.2"* 

/gg Ni/g control lung -- 317 ± 18.9"* 1,110 ± 32.7"* 2,082 5: 221.1"* 

Female 

n 7 7 7 6 

7-Month interim evaluation 

Absolute lung wt (g) 1.14 ± 0.03 1.31 ± 0.03* 1.65 ± 0.07** 1.78 ± 0.08** 

~g Ni/lung -- 226 ± 13.3"* 792 ± 86.5** 1,279 ± 132.2"* 

ttg Ni/g lung -- 173 ± 10.1"* 477 ± 44.4** 713 ± 45.2** 

ttg Ni/g control lung -- 198 ± 11.7"* 694 ± 75.8** 1,122 ± 115.9"* 

n 5 5 5 5 

15-Month interim evaluation 

Absolute lung wt (g) 1.56 ± 0.11 1.79 ± 0.10 " 2.41 ± 0.11"* 3.02 ± 0.13"* 

~ag Ni/lung -- 471 ± 42.5** 1,703 ± 140.5"* 2,810 ± 389.1"* 

~g Ni/g lung -- 262 ± 14.8"* 706 ± 41.8"* 949 ± 146.4~* 

/zg Ni/g control lung -- 302 ± 27.3** 1,093 ± 90.2"* 1,804 ± 249.7** 

* Significantly different (P <_0.05) from the control group by Williams' test (lung w~ight) or Shirley's test (lung burden parameters) 

** P~0.01 

a Mean ± standard error 

b Results were below 0.540/~g Ni (the limit of detection) for 7-month males, 0.660 ~g Ni for 7-month females, or 0.450 ~g Ni for 

15-month males and females, or below the level of quantitation. 
343 

APPENDIX I 

TISSUE BURDEN IN MICE 

TABLE I1 

TABLE I2 

TABLE I3 

Lung Weight and Lung Burden in Mice in the 16-Day Inhalation Study 

of Nickel Oxide .............................................. 344 

Lung Weight and Lung Burden in Male Mice in the 13-Week Inhalation Study 

of Nickel Oxide .............................................. 344 

Lung Weight and Lung Burden in Mice in the 2-Year Inhalation Study 

of Nickel Oxide .............................................. 345 
344 Nickel Oxide, NTP TR 451 

TABLE I1 

Lung Weight and Lung Burden in Mice in the 16-Day Inhalation Study of Nickel Oxide a 

0 mg/m 3 1.2 mg/m 3 2.5 mg/m 3 5 mg/m 3 

n 5 5 5 5 

Male 

Absolute lung weight (g) 0.159 ± 0,005 0,154 5:0.009 0.156 5:0.003 0.156 ± 0.010 

t~g Ni/lung _b 5 5: 0.1"* 7 =1: 0.5** 13 ± 0.7** 

p,g Ni/g lung -- 32 ± 2.4** 46 ± 3.6** 84 ± 7.8** 

/~g Ni/g control lung -- 31 5: 0.8** 45 5: 3.1"* 81 ± 4.5** 

Female 

Absolute lung weight (g) 0.149 5:0.006 0.133 5:0,004 0.141 ± 0.006 0.168 ::t: 0.006 

~g Ni/lung -- 4 ± 0.2** 6 ± 0.4** 12 ± 0.8** 

~g Ni/g lung -- 31 ± 2.1"* 43:1: 0.9** 71 5: 5.7** 

~g Ni/g control lung -- 27 ± 1.3"* 41 5: 2.5** 80 ± 5.7** 

** Significantly different (P_<0.01) from the control group by Dunnett's test (lung weight) or Shirley's test (lung burden parameters) 

a Mean :5: standard error 

b Results were below 0.213/zg Ni (the limit of detection), or below the level of quantitatlon. 

TABLE I2 

Lung Weight and Lung Burden in Male Mice in the 13-Week Inhalation Study of Nickel Oxide a 

0 mg/m 3 0.6 mg/m 3 2.5 mg/m 3 10 mg/m 3 

Male 

n 6 5 6 5 

Absolute lung weight (g) 0.176 5:0.012 0.179 5:0.004 0.179 5:0.014 0.244 5: 0,019"* 

~g Ni/luiIg _b 7 ± 0.6** 36 5: 3.3** 171 5: 15.5"* 

~g Ni/g lung -- 42 5: 2.9** 202 5: 18.3"* 736 5: 123.0"* 

~g Ni/g control lung -- 42 ::1: 3.4** 204 5: 18.9"* 973 5: 88.0** 

** Significantly different (P_<0.01) from the control group by Dunnett's test (lung weight) or Shifley's test (lung burden parameters) 

a Mean 5: standard error 

b Results were below 0.255 ~g Ni (the limit of detection), or below the level of quantitation. 
Tissue Burden in Mice 345 

TABLE 13 

Lung Weight and Lung Burden in Mice in the 2-Year Inhalation Study of Nickel Oxide a 

0 mg/m 3 1.25 mg/m 3 2.5 mg/m 3 5 mg/m 3 

n 5 5 5 5 

Male 

7-Month interim evaluation 

Absolute lung weight (g) 0.192 ± 0.009 0.208 ± 0.004 0.240 ± 0.010"* 0.238 ::k 0.006** 

/~g Ni/lung _b 34 5: 2.1"* 107 ± 12.0"* 246 5: 11.2"* 

ttg Ni/g lung -- 162 ± 9.6** 442 ± 37.1"* 1,034 ± 33.1"* 

~g Ni/g control lung -- 176 ± 11.0"* 556 5: 62.3** 1,283 ::1: 58.1"* 

15-Month interim evaluation 

Absolute lung weight (g) 0.234 ± 0.017 0.246 ± 0.021 0.306 ± 0.020* 0.382 ± 0.019"* 

t~g Ni/lung -- 80 5: 5.1"* 296 ± 35.5** 696 ± 81.9"* 

/xg Ni/g lung -- 331 ± 30.3** 959 ± 67.1"* 1,798 5: 134.5"* 

/zg Ni/g control lung -- 340 ± 21.8"* 1,265 5: 151.5"* 2,973 ± 349.9** 

Female 

7-Month interim evaluation 

Absolute lung weight (g) 0.178 ± 0.010 0.206 ± 0.011 0.228 5:0.019 0.232 5:0.022 

#g Ni/lung -- 35 5: 1.6"* 120 5: 8.1"* 196 5: 15.3"* 

#g Ni/g lung -- 169 5: 6.0** 533 5: 36.4** 861 5: 70.1"* 

/tg Ni/g control lung -- 195 ± 9.1"* 674 ± 45.2** 1,101 ± 86.2** 

15-M0nth )nterim evaluation 

Absoh~te lung weight (g) 0.248 5:0.010 0.264 5:0.010 0.294 ± 0.018 0.340 ::k 0 026** 

/zg Ni/lung -- 119 ± 10.1"* 365 ± 39.9** 771 5: 111.9"* 

~g Ni/g lung -- 451 ::k 31.4"* 1,237 ± 102.6"* 2,258 5: 265.1"* 

#g Ni/g control lung -- 481 5: 40.9** 1,472 ± 160.9"* 3,108 5: 451.3"* 

* Significantly different (P ~.0.05) from the control group by Williams' or Dunnett's (lung weight) or Shidey's tests (lung burden 

parameters) 

** P~0.01 

a Mean ± standard error 

b Results were below 0.400 ~g Ni (the limit of detection) for 7-month mice or 0.352 ~g Ni for 15-month mice, or below the level of 

quantitation. 
346 Nickel Oxide, NTP TR 451 
347 

APPENDIX J 

REPRODUCTIVE TISSUE EVALUATIONS 

AND ESTROUS CYCLE CHARACTERIZATION 

TABLE J1 

TABLE J2 

Summary of Reproductive Tissue Evaluations and Estrous Cycle 

Characterization for Rats in the 13-Week Inhalation Study 

of Nickel Oxide .............................................. 348 

Summary of Reproductive Tissue Evaluations and Estrous Cycle 

Characterization for Mice in the 13-Week Inhalation Study 

of Nickel Oxide .............................................. 349 
348 Nickel Oxide, NIP TR 451 

TABLE J1 

Summary of Reproductive Tissue Evaluations and Estrons Cycle Characterization for Rats 

in the 13-Week Inhalation Study of Nickel Oxide a 

0 mg/m ~ 2.5 mg/m 3 5 mg/m 3 10 mg/m 3 

Male 

n 10 9 10 10 

Weights (g), 

Right cauda 0.136 ± 0.006 0.137 ± 0.005 0.138 ± 0.005 0.145 ± 0.004 

Right epididymis 0.516 ::t: 0.015 0.487 ::1:0.011 0.505 ± 0.008 0.505 ± 0.012 

• Right testis 1.340 ± 0.028 1.438 ± 0.037 1.418 ± 0.034 1.455 ± 0.054 

Epididymal spermatozoal measurements 

Motility (%) 95.27 ± 0.51 

Abnormality (%) 0.680 ± 0.080 

Concentration (106/g cauda epididymal tissue) 

949 5:56 

94.61 ± 0.63 94.45 ± 0.38 94.03 ± 0.47 

0.822 ± 0.127 0.940 ± 0.043 0.880 ± 0.061 

874 ± 65 819 ± 53 754 ± 24** 

Female b 

n 10 9 e 10 8 d 

Estrous cycle length (days) 4.80 5:0.25 4.67:5:0.17 4.60 ± 0.16 4.75 5:0.25 

Estrous stages (% of cycle) 

Diestms 32.9 34.3 32.9 34.3 

Proestrus 8.6 12.9 12.9 14.3 

Estrus 30.0 31.4 35.7 34.3 

Metestrus 20.0 15.7 18.6 15.7 

Unclear diagnosis 8.6 5.7 0.0 1.4 

** Significantly different (P_<0.01) from the control group by Shirley's test 

a Data are presented as mean 5: standard error. 

b There is no evidence of any differences between the exposed and control groups in cycle length or in relative length of time spent in 

estrous stages. 

c Estrous cycle was longer than 7 days or was unclear in 1 of 10 animals. 

d Estrous cycle was longer than 7 days or was unclear in 2 of 10 animals. 
Sperm Morphology and Vaginal Cytology Evaluations 349 

TABLE J2 

Summary of Reproductive Tissue Evaluations and Estrous Cycle Characterization for Mice 

in the 13-Week Inhalation Study of Nickel Oxide a 

0 mg/m 3 2.5 mg/m 3 5 mg/m 3 10 mg/m 3 

Male 

n 10 10 I0 9 

Weights (g) 

Right cauda 0.010 ± 0.001 0.008 ± 0.001 0.010 5:0.001 0.010 =1:: 0.001 

Right epididymis 0.062 ± 0.003 0.056 ± 0.004 0.063 ± 0.004. 0.056 ± 0.004 

Right testis 0.121 ± 0.005 0.112 5:0.004 0.123 ± 0.004 0.106 ± 0.009 

Epididymal spermatozoal measurements 

Motility (%) 95.40 ± 0.30 

Abnormality (%) 1.70 ± 0,15 

Concentration (10~/g cauda epididymal tissue) 

1,714 ± 210 

95.40 5:0.25 95.50 ± 0.29 95.68 ± 0.28 

1.34 ± 0.13 1.62 5:0.19 2.40 ± 1.06 

1,616 ± 262 1,815 ± 190 1,735 ± 204 

Female b 

n 9 10 9 c 9 

Estrous cycle length (days) 4.11 ± 0.11 4.30 ± 0.21 4.00 ± 0.17 4.11 ± 0.11 

Estrous stages (% of cycle) 

Dicstrus 31.7 25.7 31.4 31.7 

Proestrus 19.0 11.4 14.3 23.8 

Estrus 27.0 38.6 34.J 22.2 

Metestrus 20.6 22.9 20.0 22.2 

Unclear diagnosis 1.6 1.4 0.0 0.0 

a Data are presented as mean ± standard error. Differences from the control group for all study parameters are not significant by Durm's 

or Dunnett's tests. 

b There is no evidence of any differences between the exposed and control groups in cycle length or in relative length of time spent in 

estrous stages. 

c Esti'ous cycle was longer than 7 days or was unclear in 1 of 10 animals. 
Nickel Oxide, NTP TR 451 

350 
351 

APPENDIX K 

CHEMICAL CHARACTERIZATION AND 

GENERATION OF CHAMBER CONCENTRATIONS 

PROCUREMENT AND CHARACTERIZATION OF NICKEL OXIDE ........................... 352 

AEROSOL GENERATION AND EXPOSURE SYSTEM .................................. 352 

AEROSOL CONCENTRATION MONITORING ........................................ 353 

CHAMBER ATMOSPHERE CHARACTERIZATION .................................... 354 

FIGURE K1 Schematic of the Generation System ................................. 356 

FIGURE K2 Schematic of the Nickel Oxide Aerosol Delivery System .................... 357 

FIGURE K3 Schematic of the H1000 and H2000 Exposure Chambers ..................... 358 

FIGURE K4 13-Week Nickel Oxide Inhalation Suite ............................... 359 

FIGURE K5 2-Year Nickel Oxide Inhalation Suite ................................ 360 

FIGURE K6 Daily Mean Filter Concentrations and Standard Deviations 

in the 13-Week Inhalation Study in Rats .............................. 361 

FIGUltE K7 Daily Mean Filter Concentrations and Standard Deviations 

in the 13-Week Inhalation Study in Mice .............................. 362 

FIGURE K8 Weekly Mean Filter Concentrations and Standard Deviations 

in the 2-Year Inhalation Study in Rats ............................... 363 

FIGURE K9 Weekly Mean Filter Concentrations and Standard Deviations 

in the 2-Year Inhalation Study in Mice ............................... 364 

TABLE K1 Summary of Aerosol Size Measurements for the Rat and Mouse Chambers 

in the 16-Day Inhalation Studies of Nickel Oxide ......................... 365 

TABLE K2 Summary.of Aerosol Size Measurements for the Rat and Mouse Chambers 

in the 13-Week .Inhalation Studies of Nickel Oxide ........................ 365 

TABLE K3 Summary of Aerosol Size Measurements for the 0.62, 1.25, 

and 2.5 mg/m 3 Rat Chambers in the 2-Year Inhalation Study 

off Nickel Oxide .............................................. 366 

TABLE K4 Summary of Aerosol Size Measurements for the 1.25, 2.5, 

and 5 mg/m 3 Mouse Chambers in the 2-Year Inhalation Study 

of Nickel Oxide .............................................. 367 
352 Nickel Oxide, NTP TR 451 

CHEMICAL CHARACTERIZATION AND 

GENERATION OF CHAMBER CONCENTRATIONS 

PROCUREMENT AND CHARACTERIZATION OF NICKEL OXIDE 

Nickel oxide, which was manufactured by the Socicte Metallurgiquc le Nickel (Paris, France), was 

generously supplied by International Nickel Company, Ltd., (Toronto, Ontario) in one lot (I042983), 

which was used during the 16-day, 13-week, and 2-year studies. Identity and purity analyses were 

conducted by the analytical chemistry laboratory, Midwest Research Institute (Kansas City, MO). Reports 

on analyses performed in support of the nickel oxide studies are on file at the National Institute of 

Environmental Health Sciences. 

The chemical, an olive gray powder, was identified as high temperature (sintered) nickel oxide by 

elemental, melting point, and solubility analyses. The chemical had a melting point of greater than 

300 ° C and was not soluble in boiling concentrated nitric acid or concentrated sulfuric acid. Elemental 

analysis for nickel was in agreement with the theoretical value for nickel oxide. The melting point and 

solubility characteristics were consistent with those expected for high temperature (sintered) nickel oxide 

(Weast, 1976; Rhoda et al., 1981). 

The purity of lot 1042983 was determined by elemental analysis, weight loss on drying, and spark source 

mass spectrometry. A sample of lot 1042983 was also analyzed by Truesdail Laboratories (Tustin, CA) 

for five elements to determine if it met American Society of Testing and Materials (ASTM) specifications. 

Elemental analysis for nickel (78.8 %) was in agreement with the theoretical 'value for nickel oxide. 

Weight loss on drying indicated less than 0.05% water. Spark source mass spectrometry indicated total 

impurities less than or equal to 3,500 ppm; the major inorganic impurities were cobalt (approximately 

2,200 ppm), iron (670 ppm), and sulfur (200 ppm). Analyses for nickel, cobalt, copper, iron, and sulfur 

indicated conformance with ASTM specifications for Grade 75 nickel oxide sinter (ASTM, 1974). The 

overall purity was determined to be greater than 99 %. 

No accelerated chemical stability studies were performed for nickel oxide based on literature information 

about the physical and chemical properties of the compound (Kirk-Othmer, 1978). The melting point and 

oxidation state indicate that nickel oxide should be thermally stable at temperatures up to 340 ° C when 

protected from light (Larkins, 1967; Weast, 1976). To ensure stability, the analytical chemistry 

laboratory recommended that the bulk chemical be stored protected from light at room temperature. 

The bulk chemical was stored in amber glass bottles at room temperature. Periodic monitoring of the bulk 

chemical was performed by Huffman Laboratories, Inc., (Golden, CO) prior to all studies, once during the 

16-day and 13-week studies and every 3 to 5 months during the 2-year studies by elemental analysis for 

nickel and weight loss on drying. On three occasions out of 20 analyses, the values for nickel in the 

samples fell outside the range recommended by the analytical chemistry laboratory. Occasionally, the 

weight loss on drying exceeded the specification of 0.1%. Because the excursions from specification were 

sporadic and occurred in the bulk and reference samples, it was concluded that there was no degradation 

of the bulk chemical during the studies. 

AEROSOL GENERATION AND EXPOSURE SYSTEM 

Nickel oxide aerosol was generated from 4-inch (16-day and 13-week studies) or 2-inch (2-year studies) 

fluid bed generators (FBGs). Figure K1 shows the schematic of the FBG with the gravity feed and catch 
Chemical Characterization and Generation of Chamber Concentrations 353 

pan collection systems. The FBG contained a bed of stainless steel powder of a diameter too heavy to be 

carried from the generator in the flow of air. The nickel oxide was added to the stainless steel bed, and 

the motion of the bed when air was passed through the FBG released the much smaller nickel oxide 

particles into the air. A Kr-85 discharger was placed in the generator to reduce the electrical charge on 

the aerosol. The nickel oxide aerosol was mixed with diluting air to achieve the desired concentrations 

and was delivered to the exposure chambers. Fresh nickel oxide-containing bed material was constantly 

added to the generator from a hopper located above the generator; the nickel oxide-depleted stainless steel 

powder was continually drained from the FBG through an overflow port located at the side of the 

generator. The depleted stainless steel bed material, collected in an enclosed container at the base of the 

generator, was loaded into a V-tube mixer and was mixed with a sufficient amount of nickel oxide to 

replenish the bed and maintain a stable aerosol concentration. The amount of nickel oxide added to each 

bed depended on the aerosol concentration desired. The aerosol generation assembly was enclosed in a 

walk-in hood. Air was circulated through HEPA filters to remove suspended particles in the enclosure. 

The aerosol delivery system is shown in Figure K2. 

Stainless steel, multi-tiered, whole-body exposure chambers (H1000 and H2000, Hazleton Systems, 

Aberdeen, MD) were used to expose the rats and mice in these studies (Figure K3). In the 16-day studies, 

the H2000 chambers were used for the 1.2, 2.5, and 10 mg/m 3 groups, and the H1000 chambers were 

used for the 0, 5, and 30 mg/m 3 groups. During the 13-week studies, the H2000 chambers were used for 

the 0, 0.6, 2.5, and 10 mg/m 3 groups, and the H1000 chambers were used for the 1.2 and 5 mg/m 3 

groups. In the 2-year studies, the H2000 chambers were used to expose the rats, and the H1000 chambers 

were used to expose the mice. The air flow rate in the 16-day studies corresponded to 12 5= 2 air changes 

per hour. In the 13-week studies, the air flow rate was 12 ± 2 ft3/min in the H2000 chambers and 

7 5= 1 ft3/min in the H1000 chambers, corresponding to 3.86 to 21.32 (rats) and 10.06 to 19.44 (mice) air 

changes per hour. In the 2-year studies, the air flow rate was 14.6 ± 2.0 ft3/min in the rat chambers and 

8.7 ± 1.2 fP/min in the mouse chambers, corresponding to 15 ± 2 air changes per hour. To reduce the 

spatial Variation of aerosol concentration and to increase the uniformity of mixing, the aerosol was diluted 

in a radial dilutor prior to introduction into the chamber, and a small boxer fan (Model WS 2107FL-1002, 

Newark Electronics, Chicago, IL) with a flow rate of 60 ft3/min was placed below the aerosol entrance to 

further mix the aerosol as it entered the chamber. Animal cages were rotated weekly to reduce the 

variation of concentrations of aerosols that the animals were being exposed to during the 13-week and 

2-year studies. Diagrams of the 13-week and 2-year exposure suites are shown in Figures K4 and K5, 

respectively. 

AEROSOL CONCENTRATION MONITORING 

In. the 13-week and 2-year studies, the aerosol concentrations were determined gravimetrically from three 

2-hour samples (3 L/rain flow rate) from each exposure chamber during each 6-hour exposure day. The 

background concentrations of total suspended particles in the control chambers were monitored each 

exposure day of the 2-year studies by collecting one 6-hour filter sample; samples were collected overnight 

from the control chambers during the 16-day and 13-week studies. The mean concentration of total 

suspended particles in the control chamber was 0.08 mg particles/m 3 in the 16-day studies and was 

0.07 mg particles/m 3 in the 13-week studies. In the 2-year studies, the mean concentrations of total 

suspended particles were 0.02 5= 0.01 mg particle/rag 3 in the rat control chamber and 0.01 ± 0.01 mg 

particle/m 3 in the mouse control chamber. 

All samples in the 13-week and 2-year studies were collected after the initial 8 minutes (Tgo) of aerosol 

generation at a flow rate of 3 L/rain. The flow rate was monitored with orifice meters. To determine 

aerosol concentration, samples were collected with 25 nun fiberglass filters (Type AE, Gelman, Ann 

Arbor, MI) during the 13-week studies and with 25 nun, Teflon®-coated, fiberglass filters with a pore size 
354 Nickel Oxide, NTP TR 451 

of 0.1 /zm (Zefluor, Gelman, Ann Arbor, MI) during the 2-year studies. The quantity of nickel oxide 

collected on the filters was determined gravimetrically by weighing the filters with an electrobalance 

(Cahn 29, Cahn Instruments, Cerrito, CA) before and after the collection of the samples. The aerosol 

mass concentrations were calculated by dividing the mass increment (rag) by the volume sampled (m3); the 

means and standard deviations of each chamber were calculated for each exposure day. Daily mean 

exposure concentrations for the 13-week studies are presented in Figures K6 and K7. Weekly mean 

exposure concentrations for the 2-year studies are presented in Figures K8 and K9. 

A continuous aerosol monitor (Model RAM-S, GCA, Co., Bedford, MA) was used to monitor the stability 

of the aerosol concentrations and to determine the need to adjust the aerosol generation system during 

exposures. The RAM-S was used to monitor each chamber for at least 2 minutes at the beginning, 

middle, and end of each filter sampling period. The RAM-S unit has a self-contained sampling system 

which operates at 2 L/rain. 

Aerosol concentration was also quantitated with the RAM-S. The RAM-S voltage output was calibrated 

against the mass concentration obtained gravimetrically. The average of three RAM-S voltage readings 

taken during a filter-sampling period were plotted versus the aerosol concentration determined 

gravimetrically. Linear regression analysis was performed monthly on these data, and the RAM-S voltage 

readings (volts) were converted to mass concentration (mg/m 3) based on the slope and intercept of the 

regression line fitted to the data. The mean and standard deviation of the concentrations were calculated 

each exposure day for each chamber. The coefficient of variation from the RAM-S measurement was 

used as an indication of aerosol stability for each exposure day. RAM-S and filter samples were taken at 

the middle level of the H2000 and H1000 chambers above the animal cage. The probe for the filter 

sample was at the front of each chamber, and the probe for the RAM-S was at the back of each chamber. 

CHAMBER ATMOSPHERE CHARACTERIZATION 

Aerosol size distribution was determined once during the I6-day and 13-week studies and monthly during 

the 2-year studies for each exposure chamber with a Lovelace multijet cascade impactor operated at a flow 

rate of 15 L/rain. The sampling period ranged from 30 minutes to 6 hours depending on the chamber 

concentration. Stainless steel shimstock coated with apiezon grease was used as impactor substrate. The 

amount of nickel oxide on each stage was determined by the difference in stage weight before and after 

the sample was collected. The mass medium aerodynamic diameter and the geometric standard deviation 

were calculated from the mass data, effective cutoff diameter of each stage, and impactor flow rate. The 

results are presented in Tables K1 through K4. 

Prior to the start of the studies, the generated aerosol was sampled and compared to the bulk sample by 

atomic absorption and X-ray diffraction analyses. The nickel content of both samples was identical, and 

their diffraction patterns conformed to the standard pattern (# 22-1.189) published by the Joint Committee 

on Powder Diffraction Standards. The data supports the conclusion that the generation system did not 

change the crystal structure of the bulk chemical. 

Results of analyses of the nickel content of the aerosol during the 13-week studies indicated the nickel 

content to be 78.81% ± 5.46%, which is consistent with the theoretical value of 78.58% nickel. Nickel 

oxide aerosol filter samples were collected from the 0.62 and 2.5 mg/m 3 rat chambers during week 4 of 

exposure during the 2-year study and were analyzed for nickel content by atomic absorption spectroscopy 

to verify the stability of the aerosol. Chemical analysis of these filter samples indicated that the aerosols 

contained 72 % and 70 % nickel, respectively. These values are somewhat below the average percent. 

nickel found in the bulk nickel oxide and are below the theoretical value. Since low values for nickel 
Chemical Characterization and Generation of Chamber Concentrations 355 

were occasionally reported by Huffman Laboratories for bulk chemical analysis, these low values were not 

considered to be significant. 

Uniformity of aerosol concentration in the exposure chambers was measured prior to the start of the 

studies without animals in the chambers and with animals during the first week of exposure, and was 

checked quarterly during the 2-year studies. Three samples were collected with the RAM-S at a specified 

reference point in each chamber at the start, middle, and end of the procedure. One sample each was 

collected for the other locations. The total variation of aerosol concentrations is the coefficient of 

variation of samples collected at different locations, and the temporal variation is the coefficient of 

variation of the three reference samples. In the 13-week studies, the temporal variations ranged from 

1% to 17 %, and the spatial variations ranged from. 0 % to 3 %. For rats in the 2-year studies, the mean 

temporal variations of aerosol concentration during exposure were between 1.46% and 2.76%, and the 

mean spatial variations were between 2.50% and 8.45%. For mice in the 2-year studies, the mean 

temporal variations were between 1.39% and 2.25 %, and the mean spatial variations were between 3.78% 

and 4.89%. 

The aerosol rise and fall time (Tgo) was determined with a RAM-S, and an exposure day was set at 

6 hours plus Tgo. A T~0 of 8 minutes was used during all studies. 

Residual concentration of nickel oxide in the chambers during nonexposure hours was evaluated 

gravimetrically once during the 16-day studies, once during the 13-week studies, and once during the first 

2 weeks of exposure and quarterly thereafter during the 2-year studies. The filter samples were collected 

overnight (about 15 hours) at a flow rate of 3 L/min. Samples were collected from the 30 mg/m 3 chamber 

during the 16-day studies and from the 10 mg/m 3 chamber during the 13-week studies. During the 2-year 

studies, samples were collected from the 2.5 mg/m a rat chamber and from the 5 mg/m 3 mouse chamber. 

If the weight of the material collected on the filter was greater than 200/zg, the material collected was 

analyzed for nickel content by atomic absorption spectroscopy. The mass of the particles collected on the 

filter during the 16-day and -13-week studies never exceeded 200 #g. The mass of the particles collected 

exceeded 200/zg four times during the 2-year rat study and three times during the 2-year mouse study, 

and these samples were analyzed for nickel content. Results of chemical analysis of these filter samples 

by atomic absorption spectroscopy indicated that the aerosol collected on the filter consisted chiefly of 

non-nickel-containing material. 
356 Nickel Oxide, NTP TR 451 

( 

HOPPPER FEED l 

AEROSOL 

PRESSURE DROP Kr-OS 

DIS~ 

FEED AIR 

~~CO ROTAMETER 

MPRESSED 

AIR 

PAN 

COMPREBBED AIR 

FLUIDIZING 

ORIFICE METER 

DISTRIBUTION PLATE 

READ OUT 

I BALANCE 

FIGURE K1 

Schematic of the Generation System 
Chemical Characterization and Generation of Chamber Concentrations 357 

AEROSOL DILUTION/OELIVERY SYSTEM 

~f O~ICE METER O~ICE METER GATE VALVE 

~ L, ., :.~. 

~UT.~ .: -r i 

EXHAUST 

2-WAY VALVE *, 

CONOITIONED CLEAN AIR 

CONO~TIONED CLEAN AIR 

CHAMBER 

., 

i EXHAUST 

AEROSOL 

GENERATOR 

FIGURE K2 

Schematic of the Nickel Oxide Aerosol Delivery System 
358 Nickel Oxide, NTP TR 451 

INPUT AIR 

PLATE INPUT All .I~ °~'"'°'~",,oo .....~ °~"~°'~" 

EXCRETA CATCH PAN ~~J 

EXHAUST /~/ EXHAUST 

PLATE 

FIGURE K3 

Schematic of the H1000 and H2000 Exposure Chambers 
Chemical Characterization and Generation of Chamber Concentrations 359 

2.Smglm = 

CH1 

\ 

DOOR / 

CH8 

CH2 

CH7 

lOmglm3 

ROOM 256 

O,6mglm 3 ~- 

CH3 CH4 

CONTROL 

CH5 

WALK-IN HOOD 

AEROSOL GENERATOR 

HEPA FILTERS & BLOWERS 

~FLUID BED 

GENERATOR FOR 

GONTROL CHAMBER 

jBENCH TOP 

~BALANCE 

FIGURE K4 

13-Week Nickel Oxide Inhalation Suite 
360 Nickel Oxide, NTP TR 451 

ROOM 256 

1.25 

molto .~ 

GHI 

DOOR 

/ _.~_..~---~'~~ WALK-iN HOO0 

r~r~OH'~l~ ~ ~ ,- 

I ~ I ~, I FBQO F. 3 F.~ I~] "~" I ~.,..~,.~..~o..~ 

J•• '~ 0.82 ~1 GONTROL~ I ~E~ Imlilml I~tl "---- FB G 1 

/BENCH TOP 

~BALANCE 

FIGURE K5 

2-Year Nickel Oxide Inhalation Suite 
Chemical Characterization and Generation of Chamber Concentrations 361 

C 

0 

N 

C 

E 

N 

T 

R 

A 

T 

I 

0 

N 

M 

G 

l 

M 

3 

151 

10. 

°,I ~o ~o ~'o A ~ ~ A 

EXPOSURE DAY 

FIGURE K6 

Daily Mean Filter Concentrations and Standard Deviations 

in the 13-Week Inhalation Study in Rats 
362 Nicke| Oxide, NTP TR 451 

! 

0 

N 

P 

M 

G 

I 

M 

3 

If, 

_~.,.,~_~-~.,,~.:,=~..,.,..,,-~_~.+.~,,.,~,-~,,.,.-~.,~-~.,,.,.~,,.,~ r~-.,.~,.,..,.,,,~,,,,,.,,~,~,,,,~,,~-r.,~,~',= 

~- l t ~ l .I I 

10 20 30 40 50 60 70 

I 

8'0 

EXPOSURE DAY 

FIGURE K7 

Daily Mean Filter Concentrations and Standard Deviations 

in the 13-Week Inhalation Study in Mice 
Chemical Characterization and Generation of Chamber Concentrations 363 

C 

0 

N. 

C 

E 

N 

T 

R 

A 

T 

I 

3.0- 

2.5- 

/ 

M 

3 

I 0[~._~.. ~ ~ __ ~-~-~,~.~-'-"--~---- ~ ~" .... ~- 

...~.~---~ _ ~ ~~-~ .~ ~ .... ~ ~ 

u.)l ~ I t , I I 

~ 20 40 60 80 100 

WEEK ON STUDY 

FIGURE K8 

Weekly Mean Filter Concentrations and Standard Deviations 

in the 2-Year Inhalation Study in Rats 
364 Nickel Oxide, NTP TR 451 

6.0- 

5.5. 

C 

05.0 . 

N 

C 

E 4.5 - 

N 

T 4.0. 

R 

A 

T 3.5- 

I 

0 

N 3.0- 

NEEK ON STUDY 

FIGURE K9 

Weekly Mean Filter Concentrations and Standard Deviations 

in the 2-Year Inhalation Study in Mice 
Chemical Characterization and Generation of Chamber Concentrations 365 

TABLE K1 

Summary of Aerosol Size Measurements for the Rat and Mouse Chambers 

in the 16-Day Inhalation Studies of Nickel Oxide 

Target Mass Median Geometric 

Concentration Aerodynamic Standard 

(mg/m 3) Diameter ~m) Deviation 

1.2 2.81 1.81 

2.5 3.21 1.82 

5 2.89 2.13 

i0 2.56 1.88 

30 3.29 2.04 

TABLE K2 

Summary of Aerosol Size Measurements for the Rat and Mouse Chambers 

in the 13-Week Inhalation Studies of Nickel Oxide 

Target Mass Median Geometric 

Concentration Aerodynamic Standard 

(mg/m 3) Diameter (#m) Deviation 

0.6 3.04 1.9 

1.2 3.06 2.0 

2.5 2.57 1.8 

5 2.77 1.9 

10 2.71 1.6 
366 Nickel Oxide, NTP TR 451 

TABLE K3 

Summary of Aerosol Size Measurements for the 0.62, 1.25, and 2.5 mg/m 3 Rat Chambers 

in the 2-Year Inhalation Study of Nickel Oxide 

Date 

0.62 mg/m 3 1.25 mlI/m 3 

Mass Median Geometric Mass Median Geometric 

Aerodynamic Standard Aerodynamic Standard 

Diameter (;tm) Deviation Diameter (~m) Deviation 

2.5 mg/m 3 

Mass Median Geometric 

Aerodynamic Standard 

Diameter (/~m) Deviation 

April 1988 2.47 1.85 2.49 1.59 2.37 1.86 

May 1988 2.35 1.96 2.33 1.92 2.58 1.87 

June 1988 2.26 2.05 2.46 1.71 2.29 1.78 

July 1988 2.21 2.05 2.42 1.76 2.13 1.71 

August 1988 2.09 1.98 1.99 1.76 2.19 1.61 

September 1988 2.10 2.02 2.06 1.70 2.06 1.60 

October 1988 2.38 1.77 2.20 1.66 2.31 1.58 

November 1988 2.48 1.98 2,26 1.71 2.07 1.75 

December 1988 2.15 1.88 2,13 1.84 2.16 1.58 

January 1989 2.28 2.08 2.58 3.51 2.33 1.82 

February 1989 2.14 2.05 1.95 1.92 2.27 1.76 

March 1989 2.10 1.97 2.13 1.82 2.25 1.76 

April 1989 2.46 1.95 2.15 1.95 2.29 1.76 

May 1989 2.19 1.86 2.22 1.90 2.21 .1.97 

June 1989 2.18 1.91 2.31 1.94 2.39 1.81 

July 1989 2.01 1.92 2.21 1.86 2.35 1.94 

August 1989 1.99 1.92 2.01 1.96 2.23 1.88 

September 1989 2.11 2.03 2.10 1.82 2.03 1.82 

October 1989 2.22 1.99 2.36 1.88 2.16 1.90 

November 1989 2.27 2,08 2.29 1.83 2.27 1.84 

December 1989 2.34 1,98 2.29 1.88 2,19 1.84 

January 1990 2.17 1.92 2.14 1.78 1,89 1.83 

February 1990 2.11 2.05 2.35 1.81 1,94 1.97 

March 1990 2.08 1.93 2.07 1.73 1.97 1.86 

Mean ± standard 

deviation 2.21 ~ 0.14 1.97 ± 0.08 2.23 ± 0.17 1.89 ± 0.36 2.21 ± 0.16 1.80 ± 0.11 
Chemical Characterization and Generation of Chamber Concentrations 367 

TABLE K4 

Summary of Aerosol Size Measurements for the 1.25, 2.5, and 5 mg/m 3 Mouse Chambers 

in the 2-Year Inhalation Study of Nickel Oxide 

Date 

1.25 mg/m 3 2.5 mg/m 3 

Mass Median Geometric Mass Median Geometric 

Aerodynamic Standard Aerodynamic Standard 

Diameter (#m) Deviation Diameter (pm) Deviation 

5 mg/m 3 

Mass Median Geometric 

Aerodynamic Standard 

Diameter (#m) Deviation 

May 1988 2.82 1.90 2.52 1.93 2.87 1.82 

June 1988 2.83 1.81 2.65 1.82 2.68 1.79 

July 1988 2.44 1.92 2.41 1.87 2.77 1.85 

August 1988 2.80 1.73 2.32 1.84 2.31 1.55 

September 1988 2.31 1.74 2.34 1.74 2.50 1.59 

October 1988 2.99 1.65 2.70 1.63 2.70 1.66 

November 1988 2.40 1.85 2.46 1.69 2.48 1.64 

December 1988 2.22 1.80 2.55 1.91 2.55 1.64 

January 1989 2.46 1.90 2.40 1.86 2.65 1.59 

February 1989 2.57 2.00 2.33 .1.87 2.46 i .82 

March 1989 2.30 1.88 2.32 1.73 2.60 1.80 

April 1989 2.62 1.91 2.32 1.78 2.77 1.83 

May 1989 2.56 1.86 2.43 1.85 2.60 1.76 

June 1989 2.22 1.92 2.48 1.84 2.67 1.91 

July 1989 2.21 2.00 2.15 1.84 2.52 1.80 

August 1989 2.30 1.96 2.46 1.74 2.58 1.83 

September 1989 2.32 1.85 2.34 1.79 2.49 1.72 

October 1989 2.67 1.87 2.49 1.73 2.48 1.80 

November 1989 2.40 1.78 2.50 1.81 2.72 1.74 

December 1989 2.41 1.88 2.61 1.75 2.45 1.85 

January 1990 2.'21 1.75 2.34 1.88 2.22 1.78 

February 1990 2.32 1.90 2.37 1.77 2.37 1.89 

March 1990 2.35 2.04 2.30 1.73 2.28 1.69 

April 1990 2.36 1.86 2.28 1.97 2.49 1.85 

Mean ± standard 

deviation 2,46 ± 0,22 1.87 ± 0.09 2.42 ± 0,13 1,81 ± 0.08 2.55 ± 0,16 1,76 ± 0,10 
368 Nickel Oxide, NTP TR 451 
369 

APPENDIX L 

INGREDIENTS, NUTRIENT COMPOSITION, 

AND CONTAMINANT LEVELS 

IN NIH-07 RAT AND MOUSE RATION 

TABLE L1 

TABLE L2 

TABLE L3 

TABLE L4 

Ingredients of NIH-07 Rat and Mouse Ration ........................... 370 

Vitamins and Minerals in NIH-07 Rat and Mouse Ration ................... 370 

Nutrient Composition of NIH-.07 Rat and Mouse Ration .................... 371 

Contaminant Levels in NIH-07 Rat and Mouse Ration ..................... 372 
370 Nickel Oxide, NTP TR 451 

TABLE L1 

Ingredients of NIH-07 Rat and Mouse Ration a 

Ingredients b Percent by Weight 

Ground #2 yellow shelled corn 

Ground hard winter wheat 

Soybean meal (49% protein) 

Fish meal (60% protein) 

Wheat middlings 

Dried skim milk 

Alfalfa meal (dehydrated, 17% protein) 

Corn gluten meal (60% protein) 

Soy oil 

Dried brewer's yeast 

Dry molasses 

Dicalcium phosphate 

Ground limestone 

Salt 

Premixes (vitamin and mineral) 

24.50 

23.00 

12.00 

10.00 

10.00 

5.00 

4.00 

3.00 

2.5O 

2.00 

1.50 

1.25 

0.50 

0.50 

0.25 

a NCI, 1976; NIH, 1978 

b Ingredients were ground to pass through a U.S. Standard Screen No. 16 before being mixed. 

TABLE L2 

Vitamins and Minerals in NIH-07 Rat and Mouse Ration a 

Amount Source 

Vitamins 

A 5,500,000 IU 

D3 4,600,000 IU, 

K 3 2.8 g 

d-c~-Tocopheryl acetate 20,000 IU 

Choline 560.0 g 

Folic acid 2.2 g 

Niacin 30.0 g 

d-Pantothenic acid 18.0 g 

Riboflavin 3.4 g 

Thiamine 10.0 g 

B~2 4,000/xg 

Pyridoxine 1.7 g 

Biotin 140.0 mg 

Minerals 

Iron 120.0 g 

Manganese 60.0 g 

Zinc 16.0 g 

Copper 4.0 g 

Iodine 1.4 g 

Cobalt 0.4 g 

Stabilized vitamin A palmitate or acetate 

D-activated animal sterol 

Menadione 

Choline chloride 

d-Calcium pantothenate 

Thiamine mononitrate 

Pyridoxine hydrochloride 

d-Biotin 

Iron sulfate 

Manganous oxide 

Zinc oxide 

Copper sulfate 

Calcium iodate 

Cobalt carbonate 

a Per ton (2,000 lb) of finished product 
Feed Analyses 371 

TABLE L3 

Nutrient Composition of NIH-07 Rat and Mouse Ration 

Mean :t= Standard 

Nutrient Deviation Range Number of Samples 

Protein (% by weight) 22.9 ± 0.80 

Crude fat (% by weight) 5.40 ± 0.30 

Crude fiber (% by weight) 3.60 ± 0.40 

Ash (% by weight) 6.60 _+ 0.30 

Amino Acids (% of total diet) 

Arginine 1.287 ± 0.084 

Cystine 0.306 ± 0.075 

Glycine 1.160 5:: 0.050 

Histidine 0.580 ± 0.024 

Isoleucine 0.917 ::i: 0.034 

Leucine 1.972 5:0.052 

Lysine 1.273 5:0.051 

Methionine 0.437 ± 0.115 

Phenylalanine 0.994 5:0.125 

Threonine 0.896 ± 0.055 

Trypt~phan 0.223 ± 0.160 

Tyrosine 0.677 5:: 0.105 

Valine 1.089 ± 0.057 

Essential Fatty Acids (% of total diet) 

Linoleic 2.389 ± 0.233 

Linolenic 0.277 ± 0.036 

Vitamins 

Vitamin A (IU/kg) 65,230 ± 1,933 

Vitamin D (IU/kg) 4,450 ± 1,382 

~-Tocopherol (ppm) 36.92 ± 9.32 

Thiamine (ppm) 18.90 ± 2.40 

Riboflavin (ppm) 7.92 ± 0.93 

Niacin (ppm) 100.95 ± 25.92 

Pantothenic acid (ppm) 30.30 ± 3.60 

Pyridoxine (ppm) 9.25 ± 2.62 

Folic acid (ppm) 2.51 ± 0.64 

Biotin (ppm) 0.267 ± 0.049 

Vitamin B~,_ (ppb) 40.14 ± 20.04 

Choline (ppm) 3,068 ± 314 

Minerals 

Calcium (%) 1.25 ± 0.I0 

Phosphorus (%) 0.95 ± 0.03 

Potassium (%) 0.887 ± 0.067 

Chloride (%) 0.526 ± 0.092 

Sodium (%) 0.315 ± 0.034 

Magnesium (%) 0.168 ± 0.008 

Sulfur (%) 0.274 ± 0.063 

Iron (ppm) 356.2 ± 90.0 

Manganese (ppm) 92.24 ± 5.35 

Zinc (ppm) 58.14 ± 9.91 

Copper (ppm) 11.50 ± 2.40 

Iodine (ppm) 3.70 ± 1.14 

Chromium (ppm) 1.71 ± 0.45 

Cobalt (ppm) 0.797 ± 0.23 

21.70 -- 24.20 

4.60 -- 5.90 

2.80 -- 4.30 

6.10 -- 7.30 

1.100- 1.390 

0.181 -- 0.400 

1.060- 1.220 

0.531 m 0.608 

0.867 -- 0.965 

1.850 -- 2.040 

1.200 -- 1.370 

0.306 -- 0.699 

0.665 -- 1.110 

0.824--- 0.985 

0.107 w 0.671 

0.564 w 0.794 

0.962 ~ 1.170 

1.830 -- 2.570 

0.210 -- 0.320 

4,180- 12,140 

3,000 -- 6,300 

22.5 -- 48.9 

16.0 -- 28.0 

6.10 -- 9.00 

65.0- 150.0 

23.0 -- 34.6 

5.60- 14.0 

1.80 -- 3.70 

0.19--0.35 

10.6 -- 65.0 

2,400 -- 3,430 

1.00- 1.50 

0.90 -- 1.00 

0.772 -- 0.971 

0.380 -- 0.635 

0.258 -- 0.370 

0.151 --0.180 

0.208 -- 0.420 

255.0 -- 523.0 

81.7 -- 99.4 

46.1 -- 81.6 

8.090 -- 15.39 

1.52 -- 5.83 

0.85 -- 2.09 

0.490 -- 1.15 

25 

25 

25 

25 

10 

10 

10 

10 

10 

10 

10 

10 

10 

I0 

10 

10 

10 

9 

9 

25 

4 

9 

25 

10 

9 

10 

10 

10 

10 

10 

9 

25 

25 

8 

8 

10 

10 

10 

10 

10 

10 

10 

10 

9 

6 
372 Nickel Oxide, NTP TR 451 

TABLE L4 

Contaminant Levels in NIH-07 Rat and Mouse Ration a 

Mean :t: Standard 

Deviation b Range Number of Samples 

Contaminants 

Arsenic (ppm) 0.22 ::k 0.17 0.05 -- 0.60 25 

Cadmium (ppm) 0.09:1:0.02 0.05 -- 0.10 25 

Lead (ppm) 0.25 5:0.18 0.10 -- 1.00 25 

Mercury (ppm) 0.05 5:0.02 0.02 -- 0.11 25 

Selenium (ppm) 0.42 5:0.25 0.16- 1.21 25 

Aflatoxins (ppb) c < 5.0 24 

Nitrate nitrogen (ppm) d 15.90 5:8.00 2.60 -- 24.0 25 

Nitrite nitrogen (ppm) d 0.19 5:0.15 <0.10 -- 0.60 25 

BHA (ppm) e 1.52 5:0.58 0.10 -- 2.00 25 

BHT (ppm) e 1.28 5:0.61 0.10 -- 3.00 25 

Aerobic plate count (CFU/g) e 64,828 5:72,281 6,700 -- 320,000 25 

Coliform (MPN/g) f 48 5:219 3 -- 11,200 25 

Escherichia coli (MP_N/g) f < 3 25 

Salmonella (MPN/g) r Negative 25 

Total nitrosoamines (ppb) 8.40 5:3.30 3.60 -- 16.50 25 

N-Nitrosodimethylamine (ppb) 6.20 5:2.90 2.60 -- 13.00 25 

N-Nitrosopyrrolidine (ppb) 2.15 5:1.25 0.90 -- 5.20 25 

Pesticides (ppm) 

o~-BHC h <0.01 25 

B-BHC < 0.02 25 

3,-BHC <0.01 25 

~-BHC <0.01 25 

Heptachlor < 0.01 25 

Aldrin < 0.01 25 

Heptachlor epoxide < 0.01 25 

DDE <0.01 25 

DDD <0.01 25 

DDT <0.01 25 

HCB <0.01 25 

Mirex <0.01 25 

Methoxychlor < 0.05 25 

Dieldrin < 0.01 25 

Endrin < 0.01 25 

Telodrin < 0,01 25 

Chlordane < 0.05 25 

Toxaphene < 0.1 25 

Estimated PCBs <0.2 25 

Ronnel <0.01 25 

Ethion < 0.02 25 

Trithion < 0.05 25 

Diazinon < 0.1 25 

Methyl parathion < 0.02 25 

Ethyl parathion <0.02 25 

Malathion 0.24 ::t: 0.23 <0.05- 1.00 25 

Endosulfan I < 0.01 25 

Endosulfan II < 0.01 25 

Endosulfan sulfate <0.03 25 

a CFU = colony forming units, MPN = most probable number, BHC is hexachlorocyclohexane or benzene hexachloride 

b For values less than the limit of detection, the detection limit is given as the mean. 

c No aflatoxin measurement was recorded for the lot milled on 2 October 1989. 

d Sources of contamination: alfalfa, grains, and fish meal 

e Sources of contamination: soy oil and fish meal 

f All values were corrected for percent recovery. 
373 

APPENDIX M 

SENTINEL ANIMAL PROGRAM 

METHODS .......................................................... 374 

RESULTS .......................................................... 376 
374 Nickel Oxide, NTP TR 451 

SENTINEL ANIMAL PROGRAM 

METHODS 

Rodents used in the Carcinogenesis Program of the National Toxicology Program are produced in 

optimally clean facilities to eliminate potential pathogens that may affect study results. The Sentinel 

Animal Program is part of the periodic monitoring of animal health that occurs during the toxicologic 

evaluation of chemical compounds. Under this program, the disease state of the rodents is monitored via 

serology on sera from extra (sentinel) animals in the study rooms. These animals and the study animals 

are subject to identical environmental conditions. The sentinel animals come from the same production 

source and weanling groups as the animals used for the studies of chemical compounds. 

Serum samples were collected from randomly selected rats and mice during the 13-week and 2-year 

studies. Blood from each animal was collected, allowed to clot and the serum separated. The samples 

were processed appropriately and sent to Microbiological Associates, Inc. (Bethesda, MD), for 

determination of antibody titers. The laboratory serology methods and viral agents for which testing was 

performed are tabulated below; the times at which blood was collected during the studies are also listed. 

Method and Test 

RATS 

13-Week Study 

ELISA 

PVM (pneumonia virus of mice) 

RCV (rat coronavirus) 

Sendai 

Hemagglutination Inhibition 

H-1 (Toolan's H-1 virus) 

KRV (Kilham rat virus) 

2-Year Study 

ELISA 

Mycoplasma arthritidis 

Mycoplasma pulmonis 

PVM 

RCV/SDA (rat coronavirus/sialodacryoadenitis virus) 

Sendal 

Hemagglutination Inhibition 

H-1 

KRV 

Time of Analysis 

Study termination 

Study termination 

Study termination 

Study termination 

Study termination 

Study termination 

Study termination 

7 and 15 months, study termination 

7 and 15 months, study termination 

7 and 15 months, study termination 

7 and 15 months, study termination 

7 and 15 months, study termination 
Sentinel Animal Program 375 

MICE 

13-Week Study 

ELISA 

Ectromelia virus 

GDVII (mouse encephalomyelitis virus) 

Mouse adenoma virus 

MHV (mouse hepatitis virus) 

PVM 

Reovirus 3 

Sendai 

Immunofluorescence Assay 

EDIM (epizootic diarrhea of infant mice) 

LCM (lymphocytic choriomeningitis virus) 

Hemagglutination Inhibition 

K (papovavirus) 

MVM (minute virus of mice) 

Polyoma virus 

2-Year Study 

ELISA 

Ectromelia virus 

GDVII 

LCM 

MVM 

Mouse adenoma virus 

MHV 

M. arthritidis 

M. pulmonis 

PVM 

Reovirus 3 

Sendai 

Immunofluorescence Assay 

EDIM 

LCM 

MVM 

Hemagglutination Inhibition 

K 

MVM 

Polyoma virus 

Study termination 

Study termination 

Study termination 

Study termination 

Study termination 

Study termination 

Study termination 

Study termination 

Study termination 

Study termination 

Study termination 

Study termination 

7 and 15 months, 

7 and 15 months, 

15 months, study 

7 and 15 months, 

7 and 15 months, 

7 and 15 months, 

Study termination 

Study termination 

7 and 15 months, 

7 and 15 months, 

7 and 15 months, 

study termination 

study termination 

termination 

study termination 

study termination 

study termination 

study termination 

study termination 

study termination 

7 and 15 months, Study termination 

7 months 

Study termination 

7 and 15 months, study termination 

Study termination 

7 and 15 months, study termination 
376 Nickel Oxide, NTP TR 451 

RESULTS 

For the 13-week inhalation studies with rats and mice, all serology test results were negative. Three rats 

had positive titers to M. arthritidis at the end of the 2-year study. 

Further evaluation of samples positive for M. arthritidis by immunoblot and Western blot procedures 

indicated that the positive titers may have been due to cross reaction with antibodies of nonpathogenic 

Mycoplasma or other agents. Only sporadic samples were positive, and there were no clinical signs or 

histopathologic changes of M. arthritidis infection in animals with positive titers. Accordingly, 

M. arthritidis-positive titers were considered to be false positive. 
DEPARTMENT OF 

HEALTH & HUMAN SERVICES 

Public Health Service 

National Toxicology Program 

Central Data Management 

P.O. Box 12233, MD El-02 

Research Triangle Park, NC 2~/709 

SPECIAL FOURTH-CLASS RATE 

POSTAGE AND FEES PAID 

DHHS/NIH 

Permit No. G-763 

Official Business 

Penalty for Private Use - $300 

NIH Publication No. 96-3367 

July 1996