## NTP TECHNICAL REPORT

ON THE



# TOXICOLOGY AND CARCINOGENESIS

STUDIES OF SODIUM DICHROMATE DIHYDRATE

(CAS NO. 7789-12-0)



# IN F344/N RATS AND B6C3F1 MICE

(DRINKING WATER STUDIES)

NATIONAL TOXICOLOGY PROGRAM

P.O. Box 12233

Research Triangle Park, NC 27709

July 2008

NTP TR 546

NIH Publication No. 08-5887



## National Institutes of Health

Public Health Service

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES

## FOREWORD

The National Toxicology Program (NTP) is an interagency program within the Public Health Service (PHS) of the

Department of Health and Human Services (HHS) and is headquartered at the National Institute of Environmental

Health Sciences of the National Institutes of Health (NIEHS/NIH). Three agencies contribute resources to the

program: NIEHS/NIH, the National Institute for Occupational Safety and Health of the Centers for Disease

Control and Prevention (NIOSH/CDC), and the National Center for Toxicological Research of the Food and Drug

Administration (NCTR/FDA). Established in 1978, the NTP is charged with coordinating toxicological testing

activities, strengthening the science base in toxicology, developing and validating improved testing methods, and

providing information about potentially toxic substances to health regulatory and research agencies, scientific and

medical communities, and the public.

The Technical Report series began in 1976 with carcinogenesis studies conducted by the National Cancer Institute.

In 1981, this bioassay program was transferred to the NTP. The studies described in the Technical Report series

are designed and conducted to characterize and evaluate the toxicologic potential, including carcinogenic activity,

of selected substances in laboratory animals (usually two species, rats and mice). Substances selected for NTP

toxicity and carcinogenicity studies are chosen primarily on the basis of human exposure, level of production, and

chemical structure. The interpretive conclusions presented in NTP Technical Reports are based only on the results

of these NTP studies. Extrapolation of these results to other species, including characterization of hazards and

risks to humans, requires analyses beyond the intent of these reports. Selection per se is not an indicator of a

substance’s carcinogenic potential.

The NTP conducts its studies in compliance with its laboratory health and safety guidelines and FDA Good

Laboratory Practice Regulations and must meet or exceed all applicable federal, state, and local health and safety

regulations. Animal care and use are in accordance with the Public Health Service Policy on Humane Care and

Use of Animals. Studies are subjected to retrospective quality assurance audits before being presented for public

review.

NTP Technical Reports are indexed in the NIH/NLM PubMed database and are available free of charge

electronically on the NTP website ( http://ntp.niehs.nih.gov ) or in hardcopy upon request from the NTP Central

Data Management group at cdm@niehs.nih.gov or (919) 541-3419.

## NTP TECHNICAL REPORT

ON THE



# TOXICOLOGY AND CARCINOGENESIS

STUDIES OF SODIUM DICHROMATE DIHYDRATE

(CAS NO. 7789-12-0)



# IN F344/N RATS AND B6C3F1 MICE

(DRINKING WATER STUDIES)

NATIONAL TOXICOLOGY PROGRAM

P.O. Box 12233

Research Triangle Park, NC 27709

July 2008

NTP TR 546

NIH Publication No. 08-5887



## National Institutes of Health

Public Health Service

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES

### 2



# CONTRIBUTORS

National Toxicology Program

Evaluated and interpreted results and reported findings



### M.J. Hooth, Ph.D., Study Scientist



### R.A. Herbert, D.V.M., Ph.D., Study Pathologist



### D.W. Bristol, Ph.D.

J.R. Bucher, Ph.D.

L.T. Burka, Ph.D.

R.S. Chhabra, Ph.D.

B.J. Collins, M.S.

A.P. King-Herbert, D.V.M.

G.E. Kissling, Ph.D.

D.E. Malarkey, D.V.M., Ph.D.

S.D. Peddada, Ph.D.

J.H. Roycroft, Ph.D.

C.S. Smith, Ph.D.

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

K.L. Witt, M.S.



## Southern Research Institute

Conducted studies and evaluated pathology findings



### C.D. Hébert, Ph.D., Principal Investigator



### J.E. Heath, D.V.M.

R.B. Thompson, D.V.M., Ph.D.



## Experimental Pathology Laboratories, Inc.

Provided pathology review



### M.H. Hamlin, II, D.V.M., Principal Investigator



### R.A. Miller, D.V.M., Ph.D.

J.C. Peckham, D.V.M., M.S., Ph.D.

C.C. Shackelford, D.V.M., M.S., Ph.D.



## Dynamac Corporation

Prepared quality assessment audits



### S. Brecher, Ph.D., Principal Investigator



### S. Iyer, B.S.

V. Tharakan, D.V.M. 

## NTP Pathology Working Group

Evaluated slides and prepared pathology report on rats

(September 26, 2006)



### M.P. Jokinen, D.V.M., Chairperson

Pathology Associates, A Charles River Company



### J.M. Cullen, V.M.D., Ph.D.

North Carolina State University



### S.A. Elmore, D.V.M., M.S.

National Toxicology Program



### G.P. Flake, M.D.

National Toxicology Program



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

National Toxicology Program



### W.G. Lieuallen, D.V.M., Ph.D.

Pathology Associates, A Charles River Company



### D.E. Malarkey, D.V.M., Ph.D.

National Toxicology Program



### E.E. McConnell, D.V.M., M.S.

ToxPath, Inc.



### R.A. Miller, D.V.M., Ph.D.

Experimental Pathology Laboratories, Inc.



### J.C. Peckham, D.V.M., M.S., Ph.D.

Experimental Pathology Laboratories, Inc.

Evaluated slides and prepared pathology report on mice

(November 9, 2006)



### M.P. Jokinen, D.V.M., Chairperson

Pathology Associates, A Charles River Company



### S.A. Elmore, D.V.M., M.S.

National Toxicology Program



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

National Toxicology Program



### D.E. Malarkey, D.V.M., Ph.D.

National Toxicology Program



### R.R. Maronpot, D.V.M.

National Toxicology Program



### J.C. Peckham, D.V.M., M.S., Ph.D.

Experimental Pathology Laboratories, Inc.



### C.C. Shackelford, D.V.M., M.S., Ph.D.

Experimental Pathology Laboratories, Inc.

### Sodium Dichromate Dihydrate, NTP TR 546 3



## Constella Group, Inc.

Provided statistical analyses



### P.W. Crockett, Ph.D., Principal Investigator



### L.J. Betz, M.S.

M.R. Easterling, Ph.D.

K.P. McGowan, M.B.A. 

## Biotechnical Services, Inc.

Prepared Technical Report



### S.R. Gunnels, M.A., Principal Investigator



### P.A. Gideon, B.A.

B.F. Hall, M.S.

L.M. Harper, B.S.

D.C. Serbus, Ph.D.

G.E. Simmons, M.A.

### 4



# CONTENTS

ABSTRACT

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

EXPLANATION OF LEVELS OF EVIDENCE OF CARCINOGENIC ACTIVITY

. . . . . . . . . . . . . . . . 12

TECHNICAL REPORTS REVIEW SUBCOMMITTEE

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

SUMMARY OF TECHNICAL REPORTS REVIEW SUBCOMMITTEE COMMENTS

. . . . . . . . . . . . 14

INTRODUCTION

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

MATERIALS AND METHODS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

RESULTS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

DISCUSSION AND CONCLUSIONS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

REFERENCES

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

A ppendix 

### A Summary of Lesions in Male Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

A ppendix 

### B Summary of Lesions in Female Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97

A ppendix 

### C Summary of Lesions in Male Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113

A ppendix 

### D Summary of Lesions in Female Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

A ppendix 

### E Clinical Pathology Results

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147

A ppendix 

### F Chemical Characterization and Dose Formulation Studies

. . . . . . . . . . . . . . . . . . . . . . . 157

A ppendix 

### G Water and Compound Consumption in the 2-Year Drinking Water Studies

of Sodium Dichromate Dihydrate

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169

A ppendix 

### H Ingredients, Nutrient Composition, and Contaminant Levels

in NTP

- 2000 Rat and Mouse Ration

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179

A ppendix 

### I Sentinel Animal Program

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183

A ppendix 

### J Chromium Tissue Distribution Study

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187

### Sodium Dichromate Dihydrate, NTP TR 546 5



## SUMMARY

Background

Chromium is a metal that exists in a variety of valence states, depending on surrounding conditions and what

other atoms it is bound to. The most stable forms are metallic chromium, trivalent chromium (chromium III), and

hexavalent chromium (chromium VI). Chromium VI has already been shown to cause cancer when inhaled in the

air. Because some compounds containing chromium VI occur as contaminants in drinking water, we studied the

effects of sodium dichromate dihydrate in drinking water on male and female rats and mice to identify potential

toxic or cancer-related hazards.



## Methods

We gave drinking water containing 14.3, 57.3, 172, or 516 mg of sodium dichromate dihydrate per liter of water

to groups of 50 male and female rats and female mice for 2 years. Similar groups of male mice were given 14.3,

28.6, 85.7, or 257.4 mg of sodium dichromate dihydrate per liter of water. Control animals received the same tap

water with no chemical added. At the end of the study, tissues from more than 40 sites were examined for every

animal.



## Results

Male and female rats exposed to sodium dichromate dihydrate had carcinomas of the mouth, but none occurred

in the control rats. Male and female mice receiving sodium dichromate dihydrate had greatly increased rates of

cancer of the small intestine.



## Conclusions

We conclude that sodium dichromate dihydrate in the drinking water caused oral cancers in rats and cancer of the

small intestine in mice.

### 6 Sodium Dichromate Dihydrate, NTP TR 546

# ABSTRACT

SODIUM DICHROMATE DIHYDRATE

CAS No. 7789-12-0

Chemical Formula: Na

2 

### Cr

2 

### O

7 

### • 2H

2 

### O Molecular Weight: 298.0

Synonyms: Chromic acid; dichromic acid, dihydrate; disodium dichromate dihydrate; chromium VI



### Sodium dichromate dihydrate is one of a number

of inorganic compounds containing hexavalent chro

mium (Cr VI) found in drinking water source supplies

as a contaminant resulting from various industrial

processes including electroplating operations, leather

tanning, and textile manufacturing. Because of the

lack of adequate experimental data on the toxicity

and carcinogenicity of hexavalent chromium ingested

orally and because hexavalent chromium has been

found in drinking water source supplies, the California

Congressional Delegation, the California Environmental

Protection Agency, and the California Department of

Health Services nominated hexavalent chromium to

the National Toxicology Program for study. Results of

3

- month toxicity studies in F344/N rats and B6C3F1,

BALB/c, and am3 -C57BL/6 mice were reported earlier

in NTP Toxicity Report 72. In the current study, male

and female F344/N rats and B6C3F1 mice were exposed

to sodium dichromate dihydrate (greater than 99.7%

pure) in drinking water for 2 years.



# 2-Y e ar 

# S t u d y in 

# R a t s

Groups of 50 male and 50 female rats were exposed to

drinking water containing 0, 14.3, 57.3, 172, or 516 mg/L sodium dichromate dihydrate (equivalent to 0, 5, 20, 60,

or 180 mg/L chromium) for 2 years (equivalent to aver

age daily doses of approximately 0.6, 2.2, 6, or 17 mg

sodium dichromate dihydrate/kg body weight for males

and 0.7, 2.7, 7, or 20 mg/kg for females). Survival of

exposed groups was similar to that of the control groups.

Mean body weights of 516 mg/L males and females

were less than those of the controls throughout the study.

The lower body weights were partly attributed to poor

palatability of the dosed water and consequent reduc

tions in water consumption. Water consumption by 172

and 516 mg/L rats was less than that by the controls

throughout the study. Exposure to sodium dichromate

dihydrate caused a microcytic hypochromic anemia in

rats that ameliorated with time.

Exposure to sodium dichromate dihydrate resulted in the

development of neoplasms of the squamous epithelium

that lines the oral mucosa and tongue. The incidences

of squamous cell carcinoma in the oral mucosa of

516 mg/L male and female rats were significantly greater

than those in the controls. The incidence in 172 mg/L

females exceeded the historical control ranges for drink

ing water studies and for all routes of administration.

The incidences of squamous cell papilloma or squamous 7

### 8 Sodium Dichromate Dihydrate, NTP TR 546



### cell carcinoma (combined) of the oral mucosa or tongue

of 516 mg/L male and female rats were significantly

greater than those in the controls.

Exposure concentration-related nonneoplastic liver

lesions were observed in males and females exposed

to 57.3 mg/L or greater. These included histiocytic

cellular infiltration, chronic inflammation, fatty change

(females), basophilic focus (males), and clear cell focus

(females). Increased incidences of histiocytic cellular

infiltration also occurred in the small intestine (duode

num), mesenteric lymph node, and pancreatic lymph

node of males and/or females exposed to 57.3 mg/L or

greater.



# 2-Y ear 

# S tud y in 

# M ice

Groups of 50 male mice were exposed to drinking water

containing 0, 14.3, 28.6, 85.7, or 257.4 mg/L sodium

dichromate dihydrate (equivalent to 0, 5, 10, 30, or

90 mg/L chromium) for 2 years (equivalent to aver

age daily doses of approximately 1.1, 2.6, 7, or 17 mg

sodium dichromate dihydrate/kg body weight). Groups

of 50 female mice were exposed to drinking water con

taining 0, 14.3, 57.3, 172, or 516 mg/L sodium dichro

mate dihydrate (equivalent to 0, 5, 20, 60, or 180 mg/L

chromium) for 2 years (equivalent to average daily doses

of approximately 1.1, 3.9, 9, or 25 mg/kg). Survival

of exposed groups was similar to that of the control

groups. Mean body weights of 257.4 mg/L males were

less than those of controls from months 2 through 6 of

the study, but by the end of the study, the mean body

weight of 257.4 mg/L males was only slightly less

than that of the control group. Mean body weights of

172 mg/L females were less than those of the controls

from months 3 through 12 of the study, and mean body

weights of 516 mg/L females were less than those of the

controls from month 2 until the end of the study. By

the end of the study, the mean body weight of 172 mg/L

females was 8% less than that of the controls, and the

mean body weight of 516 mg/L females was 15% less

than that of the controls. The lower body weights were

partly attri-buted to poor palatability of the dosed water

and consequent reductions in water consumption. Water

consumption by 85.7 and 257.4 mg/L males and 172

and 516 mg/L females was less than that by the controls

throughout the study. A treatment

- related microcytosis occurred in exposed mice; the mice were less affected

than the rats.

The incidences of neoplasms of the small intestine (duo

denum, jejunum, or ileum) were increased in exposed

groups of male and female mice. The incidences of

adenoma of the duodenum in 257.4 mg/L males and 172

and 516 mg/L females were significantly greater than

those in the controls. The incidence of carcinoma of

the duodenum was significantly increased in 516 mg/L

females. The incidence of adenoma of the jejunum in

516 mg/L females was significantly increased compared

to that in the controls. When the incidences of adenoma

and carcinoma were combined for all sites of the small

intestine, the incidences were significantly increased

in 85.7 and 257.4 mg/L males and 172 and 516 mg/L

females compared to those in the controls. The inci

dences in 57.3 mg/L females exceeded the historical

control ranges for drinking water studies and for all

routes of administration.

The incidences of diffuse epithelial hyperplasia were

significantly increased in the duodenum of all exposed

groups of male and female mice. The incidences of his

tiocytic cellular infiltration were significantly increased

in the duodenum of 85.7 and 257.4 mg/L males and

in 172 and 516 mg/L females. In the jejunum, the

incidences of diffuse epithelial hyperplasia and histio

cytic cellular infiltration were significantly increased in

516 mg/L females.

The incidences of histiocytic cellular infiltration of the

liver in all exposed groups of females, of the mesen

teric lymph node in all exposed groups of males and

females, and of the pancreatic lymph node of 85.7 and

257.4 mg/L males and 172 and 516 mg/L females were

significantly increased.

Tissue distribution studies showed that total chro

mium concentrations tended to increase with increasing

exposure concentration and duration of exposure.



# C onclu s ion s

Under the conditions of these 2-year drinking water

studies, there was clear evidence of carcinogenic activ

ity * of sodium dichromate dihydrate in male and female

F344/N rats based on increased incidences of squamous

### Sodium Dichromate Dihydrate, NTP TR 546 9



### cell neoplasms of the oral cavity. There was clear evi

dence of carcinogenic activity of sodium dichromate

dihydrate in male and female B6C3F1 mice based on

increased incidences of neoplasms of the small intestine

(duodenum, jejunum, or ileum). Exposure to sodium dichromate dihydrate resulted in

histiocytic cellular infiltration in the liver, small intes

tine, and pancreatic and mesenteric lymph nodes of rats

and mice and diffuse epithelial hyperplasia in the small

intestine of male and female mice.

__________

* Explanation of Levels of Evidence of Carcinogenic Activity is on page 12. A summary of the Technical Reports Review Subcommittee

comments and the public discussion on this Technical Report appears on page 14.

### 10 Sodium Dichromate Dihydrate, NTP TR 546



### Summary of the 2-Year Carcinogenesis Studies of Sodium Dichromate Dihydrate

Male Female Male Female

F344/N Rats F344/N Rats B6C3F1 Mice B6C3F1 Mice

Concentrations in 0, 14.3, 57.3, 172, or 0, 14.3, 57.3, 172, or 0, 14.3, 28.6, 85.7, or 0, 14.3, 57.3, 172, or

drinking water 516 mg/L 516 mg/L 257.4 mg/L 516 mg/L

Body weights 516 mg/L group less than 516 mg/L group less than Exposed groups similar 172 and 516 mg/L groups

the control group the control group to control group less than control group

Survival rates 28/50, 30/50, 30/49, 33/50, 32/50, 32/50, 33/50, 35/50, 35/50, 37/50, 39/50, 45/50,

36/50, 29/49 36/50, 31/50 38/50, 32/50 42/50, 42/50

Nonneoplastic effects Liver: infiltration Liver: infiltration Small intestine, Liver: infiltration

cellular, histiocyte (1/50, cellular, histiocyte (1/50, duodenum: epithelium, cellular, histiocyte (2/49,

0/50, 2/49, 5/50, 34/49) 5/50, 21/50, 42/50, 47/50) hyperplasia, diffuse 15/50, 23/50, 32/50,

(0/50, 11/50, 18/50, 45/50)

Small intestine, Small intestine, 42/50, 32/50); infiltration

duodenum: infiltration duodenum: infiltration cellular, histiocyte (0/50, Small intestine,

cellular, histiocyte (0/48, cellular, histiocyte (0/46, 2/50, 4/50, 37/50, 35/50) duodenum: epithelium,

0/48, 6/47, 36/46, 47/48) 0/49, 1/48, 30/46, 47/50) hyperplasia, diffuse

Lymph node, mesenteric: (0/50, 16/50, 35/50,

Lymph node, mesenteric: Lymph node, mesenteric: infiltration cellular, 31/50, 42/50); infiltration

infiltration cellular, infiltration cellular, histiocyte (14/47, 38/47, cellular, histiocyte (0/50,

histiocyte (13/49, 11/50, histiocyte (21/50, 18/50, 31/49, 32/49, 42/46) 0/50, 4/50, 33/50, 40/50)

30/49, 39/50, 41/49) 27/50, 36/50, 42/50)

Lymph node, pancreatic: Small intestine, jejunum:

Lymph node, pancreatic: infiltration cellular, epithelium, hyperplasia,

infiltration cellular, histiocyte (0/5, 2/13, diffuse (0/50, 2/50, 1/50,

histiocyte (17/29, 20/36, 2/10, 5/8, 12/16) 0/50, 8/50); infiltration

23/30, 32/34, 27/33) cellular, histiocyte (0/50,

0/50, 0/50, 2/50, 8/50)

Lymph node, mesenteric:

infiltration cellular,

histiocyte (3/46, 29/48,

26/46, 40/50, 42/50)

Lymph node, pancreatic:

infiltration cellular,

histiocyte (0/14, 1/12,

2/15, 7/14, 8/13)

### Sodium Dichromate Dichromate Dihydrate, Dihydrate, NTP TR 546 11



### Summary of the 2-Year Carcinogenesis Studies of Sodium Dichromate Dihydrate

Male Female Male Female

F344/N Rats F344/N Rats B6C3F1 Mice B6C3F1 Mice

Neoplastic effects Oral mucosa: squamous Oral mucosa: squamous Small intestine, Small intestine,

cell carcinoma (0/50, cell carcinoma (0/50, duodenum: adenoma duodenum: adenoma

0/50, 0/49, 0/50, 6/49) 0/50, 0/50, 2/50, 11/50) (1/50, 0/50, 1/50, 5/50, (0/50, 0/50, 2/50, 13/50,

15/50) 12/50); carcinoma (0/50,

Oral mucosa or tongue: Oral mucosa or tongue: 0/50, 0/50, 1/50, 6/50)

squamous cell papilloma squamous cell papilloma Small intestine,

or squamous cell or squamous cell duodenum, jejunum, Small intestine, jejunum:

carcinoma (0/50, 1/50, carcinoma (1/50, 1/50, or ileum: adenoma adenoma (0/50, 1/50,

0/49, 0/50, 7/49) 0/50, 2/50, 11/50) (1/50, 1/50, 1/50, 5/50, 0/50, 2/50, 5/50)

17/50); carcinoma (0/50,

2/50, 1/50, 3/50, 5/50); Small intestine,

adenoma or carcinoma duodenum, jejunum,

(1/50, 3/50, 2/50, 7/50, or ileum: adenoma

20/50) (0/50, 1/50, 2/50, 15/50,

16/50); carcinoma (1/50,

0/50, 2/50, 3/50, 7/50);

adenoma or carcinoma

(1/50, 1/50, 4/50, 17/50,

22/50)

Level of evidence of Clear evidence Clear evidence Clear evidence Clear evidence

carcinogenic activity

### 12 Sodium Dichromate Dihydrate, NTP TR 546



## 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

incidence 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.

For studies showing multiple chemical-related neoplastic effects that if considered individually would be assigned to different levels of evidence

categories, the following convention has been adopted to convey completely the study results. In a study with clear evidence of carcinogenic

activity at some tissue sites, other responses that alone might be deemed some evidence are indicated as “were also related” to chemical

exposure. In studies with clear or some evidence of carcinogenic activity, other responses that alone might be termed equivocal evidence are

indicated as “may have been” related to chemical exposure.

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.

### Sodium Dichromate Dihydrate, NTP TR 546 13



## 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 sodium dichromate dihydrate

on May 16, 2007, 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 the 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.



### Nancy Kerkvliet, Ph.D., Chairperson

Department of Environmental and Molecular Toxicology

Oregon State University

Corvallis, OR



### Christopher Bradfield, Ph.D.

McArdle Laboratory for Cancer Research

University of Wisconsin

Madison, WI



### Kenny S. Crump, Ph.D.

Environ International

Ruston, LA



### Prescott Deininger, Ph.D.

Tulane University Medical Center

New Orleans, LA



### Jon Mirsalis, Ph.D.

SRI International

Menlo Park, CA



### Harish Sikka, Ph.D., Principal Reviewer

Environmental Toxicology and Chemistry Laboratory

State University of New York College at Buffalo

Buffalo, NY



### Keith Soper, Ph.D.

Merck Research Laboratories

West Point, PA



### Vernon Walker, D.V.M., Ph.D., Principal Reviewer

Lovelace Respiratory Institute

Albuquerque, NM 

### Special Ad Hoc Reviewers

Russell C. Cattley, V.M.D., Ph.D.

Amgen

Thousand Oaks, CA



### Raymond F. Novak, Ph.D., Principal Reviewer

Institute of Environmental Health Sciences

Wayne State University

Detroit, MI



### Michael V. Pino, D.V.M., Ph.D.

Drug Safety Evaluation

Sanofi-aventis

Bridgewater, NJ

### 14 Sodium Dichromate Dihydrate, NTP TR 546



### On May 16, 2007, the draft Technical Report on

the toxicology and carcinogenesis studies of sodium

dichromate dihydrate 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, NC.

Dr. M.J. Hooth, NIEHS, introduced the toxicology and

carcinogenesis studies of sodium dichromate dihydrate

by discussing the uses of chromium, the rationale for

study, and the short-term studies; describing the design

of the long-term studies; and reporting on survival and

body weight effects and compound-related neoplastic

and nonneoplastic lesions. Dr. R.A. Herbert, NIEHS,

described the histopathologic details of several of the

observed lesions. The proposed conclusions for the

2

- year studies were clear evidence of carcinogenic

activity of sodium dichromate dihydrate in male and

female F344/N rats and clear evidence of carcinogenic

activity of sodium dichromate dihydrate in male and

female B6C3F1 mice.

Dr. Walker, the first principal reviewer, agreed with

the proposed conclusions. He differed with one of

the public responses to the report that suggested there

should be more discussion of sites with decreased tumor

incidence, noting that the primary purpose of the study

was to detect carcinogenic responses. He felt the dis

cussion of other studies, some with conflicting results,

was balanced. He felt it was noteworthy that, although

chromium was detected at other tissue sites, the main

carcinogenic response in mice was in the small intestine,

primarily in the duodenum and decreasing farther down

the intestinal tract.

Dr. Novak, the second principal reviewer, also agreed

with the proposed conclusions. He inquired whether

any clinical chemistry panel had been performed to

detect changes in hormone levels. He asked if any of the

observed histiocytic cellular infiltration could be associ

ated with inflammation.

Dr. Sikka, the third principal reviewer, agreed with the

proposed conclusions and inquired if there was any

explanation for the difference in the organ-specific sus

ceptibility of the two rodent species to the carcinogenic

effects of sodium dichromate dihydrate.

Dr. Hooth noted that a couple of tumors were seen in

the ileum of male mice, and Dr. Walker replied that

it was still interesting that the numbers of tumors did

decrease progressively down the intestinal tract. In

response to Dr. Novak, Dr. Hooth replied that because

this was a study of hexavalent chromium, examinations

of the effects of trivalent chromium on lipid or carbo

hydrate metabolism were not performed. Regarding

the histiocytic cellular infiltration, Dr. Herbert replied

that these were not granulomas, with some causative

agent like bacteria or fungus or necrosis, and no addi

tional inflammatory cells were seen in association with

the infiltration. In response to Dr. Sikka, Dr. Hooth

replied that in a survey of 21 NTP studies that caused

neoplasms of the oral cavity in rats, none caused similar

neoplasms in male mice and only one in female mice.

Dr. Hooth added that further studies were underway to

characterize the absorption of chromium in the stomach

and intestine.

Dr. Mirsalis inquired if the palatability of the chemical

may have affected water consumption or body weights of

the animals. Dr. Cattley asked about the sampling pro

cedures for oral cavity lesions and if all the carcinomas

were detected by gross examination. Dr. Herbert replied

that a reexamination of all the tissue samples provided

confidence that all potential lesions were detected.

Dr. Kirkvliet said that written comments had been

submitted by six organizations: the Sapphire Group;

the Department of Health Sciences of the University of

Genoa, Italy; the Interfaith Community Organization;

Exponent, Inc.; Consulting Scientists; and the

Environmental Working Group.

Mr. T. McKee, representing the Interfaith Community

Organization of New Jersey, said the NTP had produced

a well-designed and meticulously executed study and

an insightful and illuminating report. He urged that the

report be completed expeditiously in light of the need for

the study results by regulatory agencies.

Dr. D.M. Proctor, representing Tierra Solutions, Inc.,

noted that the chromium concentrations in the NTP 

## SUMMARY OF TECHNICAL REPORTS REVIEW SUBCOMMITTEE COMMENTS

### Sodium Dichromate Dihydrate, NTP TR 546 15



### study were 50 to 100 times higher than the existing

drinking water standards. She indicated that no epide

miology studies in the literature indicated increases in

oral cavity or intestinal tumors as a result of exposure

to chromium. She also claimed that the body weights

and water consumption of the study animals were sig

nificantly lower than for the control groups and sug

gested that lower palatability and dehydration may have

affected the physiology of the exposed animals. She

speculated that dehydration could lead to lower produc

tion of saliva, which might affect the ability of animals

to reduce chromium VI.

Dr. Walker inquired if the water consumption was

indeed altered significantly in this study. Dr. Hooth

discussed the criteria for the diagnosis of dehydra

tion, which included clinical observations of circula

tory hypo-volemia, including loss of skin turgor, dry

mucous membranes, retraction of eyes, and even shock

and increases in clinical pathology parameters such as

albumin, hematocrit, urea nitrogen, or urine specific

gravity. None of these indicators was observed in the

present study. Dr. Hooth also presented plots showing

that only one dosed group of male rats varied by more

than 10% from controls late in the study, and that water

consumption on a body weight basis was nearly identical

for exposed and control rats.

Dr. Walker moved, and Dr. Soper seconded, that the

conclusions be accepted as written. The motion was

approved unanimously with seven votes.

### 16 Sodium Dichromate Dihydrate, NTP TR 546

### 17



# INTRODUCTION

SODIUM DICHROMATE DIHYDRATE

CAS No. 7789-12-0

Chemical Formula: Na

2 

### Cr

2 

### O

7 

### • 2H

2 

### O Molecular Weight: 298.0

Synonyms: Chromic acid; dichromic acid, dihydrate; disodium dichromate dihydrate; chromium VI



# C h e m i ca l a nd 

# P hys i ca l 

# P r ope r tie s

Sodium dichromate dihydrate exists in solid form as red

dish to bright orange crystals, which become anhydrous

when heated to approximately 100° C. The anhydrous

form has a melting point of 356.7° C ( Merck , 1996).

The water solubility of sodium dichromate dihydrate is

230 g/L at 0° C. Chromium is a group 6 transition metal

and occurs in the earth’s crustal rock at a concentration

averaging 122 ppm. It has six oxidation states. The most

stable states are metallic chromium (Cr), trivalent chro

mium (Cr III), and hexavalent chromium (Cr VI). Cr VI

is typically present in complexes with halide (chromyl

chloride) and oxygen ligands (chromium trioxide, chro

mate, dichromate). Sodium dichromate dihydrate is one

of a number of inorganic compounds that contain Cr VI.

Other representatives of this class of compounds include

calcium chromate, chromium trioxide, sodium chromate

and dichromate, potassium chromate and dichromate,

lead chromate, strontium chromate, and zinc chromate.

The physical properties and water solubility of these

compounds vary considerably. In aqueous solution,

dichromate and chromate are in equilibrium. The form

of Cr VI present depends on pH and concentration. At

physiological pH and millimolar concentrations, Cr

VI exists primarily as the chromate ion (Hamilton and Wetterhahn, 1988). The proportion existing as dichro

mate increases as the concentration increases and/or the

pH is decreased.

Cr VI is easily reduced to Cr III in acidic solutions

containing organic molecules such as proteins, DNA,

or glutathione. Glutathione is also capable of reducing

Cr VI at neutral pH at a slower rate than under acidic

conditions (Zhitkovich, 2005).



# P r od uc tion 

# , U s e



# ,

a nd 

# H uma n 

# E xpo sur e

Metallic chromium is produced by reduction of chromite

ore. Sodium dichromate is produced by roasting chro

mite ore with soda ash and is used for the production of

other chromium compounds (Hartford, 1979; Westbrook,

1979). Metallic chromium is used in the metallurgical

industry for the production of stainless steel and ferrous

and nonferrous alloys. The major uses of chromium in

the chemical and manufacturing industries include the

production of chromium pigments and in metal finish

ing, leather tanning, and wood preservation (Barnhart,

1997). Chromium enters the environment from combus

-

### 18 Sodium Dichromate Dihydrate, NTP TR 546



### tion processes and ore processing mainly as chromium

(III) oxide. Cr VI has been detected in fly ash from

power plants (Stern, 1982). Both Cr III and Cr VI enter

water resources by leaching from soil or from industrial

contamination (Pellerin and Booker, 2000) as well as

from atmospheric fallout. A Cr VI concentration as high

as 580 μg/L was found in a groundwater monitoring

well in Hinkley, California (Pellerin and Booker, 2000).

Detectable levels of hexavalent chromium have been

reported in approximately 30% of the drinking water

sources monitored in California, which has a 1 μg/L

detection limit for purposes of reporting (CDHS, 2004);

87% of those sources had concentrations ranging from 1

to 10 μg/L. The United States Environmental Protection

Agency has set a maximum contaminant level of 100

μg/L for total chromium in drinking water (ATSDR,

2000). The California state limit is 50 μg/L of total

chromium in drinking water (CDHS, 2004). Human

exposure to chromium occurs through food, water, and

air. The highest exposure to Cr VI occurs occupation

ally to workers involved in chrome plating, chromate

production, and stainless steel welding. Exposure in

these situations is typically by inhalation or dermal con

tact. Dermal exposure to chromium compounds results

in irritation and ulceration of the skin and causes allergic

contact dermatitis in sensitized individuals. Additional

information on human exposure to chromium and chro

mium compounds can be found in the Toxicological

Profile for Chromium (ATSDR, 2000).



# A bs o r ption



# , D i s t r i bu tion



# ,

M et ab oli sm



# , a nd 

# E x cr etion

Chromium and chromium compounds are found to

be absorbed after oral, dermal, or inhalation exposure

(Wahlberg and Skog, 1965; Wahlberg, 1970; Kerger

et al. , 1997; Mancuso, 1997). Current analytical proce

dures cannot differentiate between the oxidation states

of chromium in biological tissues so total chromium

content is measured in excreta and tissues. Most studies

of absorption of Cr III or Cr VI after oral administration

to rodents found that only 1% or 2% of the administered

dose is bioavailable, whereas similar studies with humans

report somewhat higher numbers (ATSDR, 2000), par

ticularly for Cr VI. It is thought that Cr VI is poorly

absorbed when ingested due to its rapid reduction to

less soluble Cr III in the presence of food and the acidic

environment encountered in the stomach (Sutherland

et al. , 2000). Cr III is less efficiently absorbed than Cr

VI compounds, and this is attributed to a difference in their respective methods of transport into cells. Cr VI

enters cells by facilitated diffusion via nonspecific anion

channels, while Cr III enters cells by passive diffusion

or phagocytosis of precipitates resulting in much lower

uptake (ATSDR, 2000).

Human and animal studies show that chromium is

widely distributed in the body after exposure to Cr VI,

with liver, kidney, spleen, and bone having higher con

centrations than other tissues (MacKenzie et al. , 1959;

Coogan et al. , 1991; Kargacin et al. , 1993; Costa, 1997;

Mancuso, 1997). Rats consuming up to 10 mg/L Cr VI

as potassium chromate in drinking water for 44 weeks

had elevated chromium levels in bone, kidney, liver

(females only), and testis (males only) (Sutherland et

al. , 2000). Other studies showed that chromium can

cross the placenta (Casey and Hambidge, 1984; Saxena

et al. , 1990; Kirpnick-Sobol et al. , 2006). Higher tis

sue chromium levels were found in rats receiving Cr VI

orally than in those receiving an equivalent dose of Cr

III (Costa, 1997). Following uptake by erythrocytes

and tissues, Cr VI is thought to undergo reduction to Cr

III intracellularly, primarily by ascorbate ( Sugiyama

, 1992).

Ingested chromium is excreted primarily in the feces

because of its poor absorption. Absorbed chromium

appears to be primarily excreted in the urine (Donaldson

and Barreras, 1966; Sayato et al. , 1980). O’Flaherty

(1993, 1996) has constructed a physiologically based

pharmacokinetic model for Cr VI compounds in the rat,

and the ATSDR (2000) has outlined distribution and

clearance models for Cr III in humans.

Prior to selection of rats and mice as the test species for

the studies in the current Technical Report, the National

Toxicology Program (NTP) conducted a comparative

absorption study of sodium dichromate dihydrate (Cr VI)

administered in the drinking water to F344/N rats,

B6C3F1 mice, and Hartley guinea pigs (NTP, 2007a).

Concentrations of total chromium were determined in

blood and kidney. Guinea pigs were chosen for study,

in addition to rats and mice, because they more closely

resemble humans in that they do not have a forestomach

and they require vitamin C (a reducing agent) in their

diet. In all three species, chromium in blood and kidney

increased with exposure concentration (NTP, 2007a).

Although differences were seen in the absolute amounts

of chromium in kidney and blood, uptake as a func

tion of exposure concentration did not appear to differ

qualitatively in guinea pigs when compared to rats and

### Sodium Dichromate Dihydrate, NTP TR 546 19



### mice. This suggests that the presence of a forestomach

did not fundamentally alter the handling of Cr VI in the

gastrointestinal tract. Kidney chromium concentration

was highest in rats, followed by mice and guinea pigs.

For blood, guinea pigs had the highest concentrations,

followed by mice and rats. The concentrations of chro

mium in blood and kidney were in general agreement

with values observed by Sutherland et al. (2000).



# T oxi c it y

Cr III is an essential trace element. The recommended

daily intake of Cr III for adults ranges between 25 and

45 μg (IOM, 2001). Cr III deficiency contributes to

glucose intolerance and diabetes mellitus (Type 2).

Chromium appears to increase sensitivity to insulin. The

mechanism involves increased insulin binding through

increasing the number of insulin receptors and increas

ing insulin receptor phosphorylation in the presence of

insulin and a low molecular weight chromium complex

(Anderson, 1998). Cr III displays little to no toxicity in

humans and animals (ATSDR, 2000).

The toxicity of Cr VI in humans and animals has

been reviewed extensively (Costa 1997; USEPA, 1998;

ATSDR, 2000; Costa and Klein, 2006). More recently,

the NTP performed 3-month studies of sodium dichro

mate dihydrate in male and female F344/N rats and

B6C3F1 mice to aid in the design and dose selection for

these 2-year carcinogenicity studies of sodium dichro

mate dihydrate (NTP, 2007a). Rats and mice were given

drinking water containing 0, 62.5, 125, 250, 500, or

1,000 mg sodium dichromate dihydrate/L for 3 months.

All rats and mice survived to the end of the studies.

Final mean body weights and body weight gains were

less than those of controls in male rats exposed to 500 or

1,000 mg/L, female rats exposed to 1,000 mg/L, and in

male and female mice exposed to 125 mg/L or greater.

Exposure to sodium dichromate dihydrate caused a

microcytic hypochromic anemia in rats and mice, but the

severity was less in mice. The primary nonneoplastic

lesions were observed in the glandular stomach of rats

exposed to 1,000 mg/L and included focal ulceration,

regenerative epithelial hyperplasia, and squamous epi

thelial metaplasia. Histiocytic cellular infiltration was

observed in the duodenum of rats and mice, the liver

of female rats, and the mesenteric lymph nodes of mice

exposed to 125 mg/L or greater. Histiocytic cellular

infiltration was also observed in the pancreatic lymph

nodes of rats exposed to 1,000 mg/L. All exposed

groups of mice had significantly increased incidences of

epithelial hyperplasia of the duodenum. The NTP examined the potential of sodium dichromate

dihydrate exposure via drinking water to modulate

immune function in female B6C3F1 mice, F344/N rats,

and Sprague-Dawley rats by conducting 28-day range

finding studies (NTP, 2007b,c,d). Sodium dichromate

dihydrate exposure concentrations in the mice were

0, 15.6, 31.25, 62.5, 125, or 250 mg/L and in the rats

were 0, 14.3, 57.3, 172, or 516 mg/L. No significant

signs of overt toxicity were observed in these studies.

Reductions in final mean body weight and body weight

gain were observed in 250 mg/L B6C3F1 mice and

516 mg/L Sprague-Dawley rats. F344/N and SpragueDawley rats in the 172 and 516 mg/L groups consumed

significantly less water than the control animals, which

was attributed to poor palatability of the drinking water

solutions. Sodium dichromate dihydrate exposure did

not produce significant changes in organ weights. In

250 mg/L mice, some of the erythroid parameters were

significantly decreased (5% to 7%) including hemo

globin, hematocrit, mean cell volume, and mean cell

hemoglobin. In rats, hematology parameters were not

affected. Sodium dichromate dihydrate exposure pro

duced minimal effects in the various immunological

parameters evaluated in mice and rats. There were no

biologically meaningful changes in spleen cell numbers

or in the percentage and absolute number of B cells,

T cells, CD4 + 

### T cells, CD8 + 

### T cells, natural killer cells,

and macrophages. Sodium dichromate dihydrate expo

sure did not produce a reproducible significant effect

on the IgM antibody-forming cell response to sheep red

blood cells or to the T-dependent antigen keyhole limpet

hemocyanin. There was no effect of sodium dichromate

dihydrate on cell

- mediated immunity and natural killer

cells evaluated using anti-CD3 antibody mediated T cell

proliferation and the cytotoxic assay of YAC-1 cells,

respectively.

Renal effects observed in rats administered Cr VI (as

potassium chromate, 13.5 mg/kg per day for 20 days) by

gavage included increased accumulation of lipid, trig

lycerides, and phospholipids in different regions of the

kidney than in controls and inhibited kidney membrane

enzymes (alkaline phosphatase, acid phosphatase, glu

cose

- 6

- phosphatase, and lipase) (Kumar and Rana, 1982,

1984). Oliguria and proteinuria were also observed in

rats exposed to Cr VI (as sodium chromate, 100 mg/kg

per day for 28 days) in drinking water (Diaz-Mayans

et al. , 1986).

A number of studies have reported reproductive effects

in rats and mice orally exposed to Cr VI. These stud

ies utilized similar exposure concentrations (250 to

### 20 Sodium Dichromate Dihydrate, NTP TR 546



### 1,000 mg/L) of potassium dichromate provided in the

drinking water of female rats and mice prior to mating or

during gestation. Cr VI exposure consistently resulted in

increased preimplantation and postimplantation losses,

resorptions, and stillbirths and decreased numbers of

corpora lutea and numbers of fetuses (live and dead)

(Trivedi et al. , 1989; Junaid et al. , 1996a,b; Kanojia

et al. , 1996, 1998). In addition, these studies provided

evidence that Cr VI is a developmental toxicant in rats

and mice. Fetuses were consistently reported to have

retarded development, decreased fetal body weight and

crown-rump length, and higher incidences of subdermal

hemorrhagic patches and kinky short tails. There was

also a significant reduction in ossification in caudal,

parietal, and interparietal bones of the fetuses.

In contrast, results of NTP studies in BALB/c mice and

Sprague-Dawley rats showed that potassium dichromate

was not a reproductive toxicant when administered in the

diet for 9 weeks followed by an 8

- week recovery period

(NTP, 1996a,b). However, rats and mice administered

potassium dichromate by diet (8.4 and 9.8 mg Cr VI/kg

body weight per day for male and female rats, respec

tively; 32.2 and 48 mg Cr VI/kg body weight per day

for male and female mice, respectively) showed reduced

mean red cell volume and mean red cell hemoglobin.

This effect was not seen at lower exposure concentra

tions. Similar decreases were seen in a multigeneration

study of mice given potassium dichromate in the diet.

The decreases were seen in BALB/c males receiving

Cr VI at 16 mg/kg per day and 36.7 mg/kg per day and

BALB/c females receiving Cr VI at 7.8 mg/kg per day

(NTP, 1997).

Toxicity of Cr VI has not been confirmed in all animal

studies. In a drinking water study, rats given Cr VI

(as potassium chromate, 3.6 mg/kg per day) for 1 year

showed no evidence of hepato- or nephrotoxicity and no

alteration in hematology or clinical chemistry param

eters (MacKenzie et al. , 1958).



# C arc ino g eni c it y

Exposure to Cr VI compounds by inhalation has long

been recognized as carcinogenic to humans. The United

States Department of Health and Human Services, the

United States Environmental Protection Agency, and

the International Agency for Research on Cancer classi

fied Cr VI compounds as human carcinogens based on

increased incidences of lung cancers in workers in the chromium industry and in experimental animals exposed

to these compounds by inhalation (IARC, 1990; Cohen

et al. , 1993; NTP, 1998). The specific compounds

listed as carcinogens include calcium chromate, chro

mium trioxide, lead chromate, strontium chromate, and

zinc chromate.

Although Cr VI compounds are demonstrated carcino

gens by the inhalation route, it has been suggested that

the reductive capacity of the gut would be adequate to

prevent Cr VI from being a carcinogen when ingested

(De Flora et al. , 1997; Proctor et al. , 2002). Little data

exist regarding health effects resulting from ingestion of

Cr VI compounds. A review of the few epidemiological

studies that evaluated populations that were exposed to

Cr VI in drinking water or in soil or slag fill concluded

that these studies did not provide definitive evidence

of an increase in cancer incidence or mortality rates

(Proctor et al. , 2002). However, a retrospective mortal

ity study of a population living near a chromium smelting

plant in the People’s Republic of China found increased

incidences of lung and stomach tumors as compared to

those of the general population. The authors did not esti

mate exposure levels nor was the size of the population

specified (Zhang and Li, 1987; ATSDR, 2000). More

recently, Sedman et al. (2006) reevaluated the findings

of this study as well as additional reports by the inves

tigators and confirmed the significant increases in lung

and stomach neoplasms.

Only one lifetime animal carcinogenicity study was

identified in the literature in which hexavalent chro

mium was administered in the drinking water. Three

generations of NMRI mice were exposed to 9 mg Cr

VI/kg body weight administered in the drinking water

as potassium chromate. In treated mice, two of 66

females developed forestomach carcinomas and nine of

66 females and one of 35 males developed forestomach

papillomas. Forestomach papillomas were observed in

the vehicle controls (2 of 79 females and 3 of 47 males),

but no carcinomas were observed in the vehicle controls.

Most of the tumors were observed in the F

0 

### generation.

The increased incidence of forestomach tumors in the

treated mice was not statistically significant (Borneff

et al. , 1968; ATSDR, 2000). However, when benign

and malignant forestomach neoplasms were combined in

the three generations of female mice, there was a statisti

cally significant increase compared to the control group

(Sedman et al. , 2006). This study has several limitations

including high early mortality in the F

0 

### generation as a

### Sodium Dichromate Dihydrate, NTP TR 546 21



### result of ectromelia (mousepox) virus.

Davidson et al. (2004) showed that exposure to potas

sium chromate in drinking water enhanced the incidence

of ultraviolet radiation-induced skin tumors in a hairless

mouse model. Female SK1-hrBR mice were exposed

for 6 months to ultraviolet light at a constant energy

of 1.18 kJ/m 2 

### and to potassium chromate in drinking

water at 0.5, 2.5, or 5.0 mg/L. There was an exposure

concentration-dependent increase in the number of skin

neoplasms in mice exposed to ultraviolet light and potas

sium chromate, which was statistically significant at the

two highest chromate doses. The authors concluded that

Cr VI can increase susceptibility to carcinogenesis fol

lowing drinking water exposure.

Trivalent chromium exposure is not considered to pose a

significant cancer risk in humans or in animals (ATSDR,

2000). There was no evidence of carcinogenicity in

male or female Becton Dickinson rats fed diets contain

ing up to 5% chromium oxide (2,040 mg Cr III/kg per

day), 5 days per week for 2 years, or in the offspring

of rats treated for 60 days prior to gestation and during

gestation, after 600 days of observation (Ivankovic and

Preussmann, 1975).



# G eneti c 

# T oxi c it y

Most studies measuring genetic damage endpoints in

humans occupationally exposed to atmospheric hexava

lent chromium reported results consistent with chro

mium-induced chromosomal damage (IARC, 1990). In

several studies, elevated frequencies of sister chromatid

exchanges and chromosomal aberrations were reported

in lymphocytes of Cr VI-exposed workers. Correlations

were documented in some of these studies between the

concentrations of chromium in the workplace or the

duration of exposure and the amount of genetic dam

age detected. In recent studies, evaluation of biological

samples including exfoliated buccal cells and peripheral

lymphocytes from workers (electroplaters or welders)

exposed to chromium by inhalation revealed significant

increases in micronuclei, which are indicators of struc

tural and numerical chromosome changes (Vaglenov et

al. , 1999; Benova et al. , 2002; Danadevi et al. , 2004).

Chromosomal aberrations have also been observed in

cultured human bronchial epithelial cells exposed to

soluble sodium chromate (VI) and particulate lead chro

mate (VI) (Wise et al. , 2006). No studies were located

regarding genotoxic effects in humans after oral expo

sure to hexavalent chromium compounds. Hexavalent chromium is genotoxic in a number of

in vitro and in vivo test systems, although responses are

somewhat variable depending on protocol details and the

type of chromium salt that is assayed. Overall, the data

clearly indicate that in appropriate test systems, Cr VI

exposure results in increased frequencies of gene muta

tions and chromosomal alterations. The extensive litera

ture on the mutagenicity of chromium compounds has

been reviewed by a number of authors, most recently by

IARC (1990) and by De Flora et al. (1990). To summa

rize the findings briefly, positive results were obtained

in vitro with Cr VI compounds in gene mutation tests

using Salmonella typhimurium or Escherichia coli (most

recently, positive results reported in NTP, 2007a);

forward mutation and mitotic gene conversion assays

in yeast; mammalian cell (including human cell lines)

chromosomal damage assays that measured increases in

sister chromatid exchanges, chromosomal aberrations,

or micronuclei; mutation induction at the tk locus in

L5178Y mouse lymphoma cells; and tests for induction

of DNA strand breaks or DNA synthesis inhibition in

a variety of mammalian cells. In vivo , positive results

were seen in short-term assays in laboratory rodents for

induction of chromosomal damage and micronuclei fol

lowing administration of Cr VI by intraperitoneal injec

tion. Comparative micronucleus assays in various strains

of male and female mice (ms, BDF1, CD-11, ddY, ICR)

revealed no sex- or strain-related differences in overall

results (CSGMT, 1986, 1988). Route of administration

was shown to be a factor, however, with intraperitoneal

injection administration (up to 80 mg/kg) of potassium

dichromate giving positive results and oral gavage (up to

320 mg/kg) giving negative results in two strains (MS/

Ae and CD-1) of male mice (Shindo et al. , 1989).

Recent results from in vivo chromosomal damage assays

in animals using drinking water as the route of adminis

tration have given mixed results. De Flora et al. (2006)

measured the frequency of micronucleated erythrocytes

in peripheral blood of BDF1 or Swiss mice exposed to

sodium dichromate dihydrate or potassium dichromate

in drinking water (up to 500 mg chromium VI/L for

210 days); no alterations in the frequencies of micronu

cleated erythrocytes were seen and the authors suggested

that the absence of genotoxicity by this route of exposure

provided evidence for gastrointestinal detoxification of

Cr VI. In contrast, exposure of adult BDF1 or Swiss

mice to Cr VI by intraperitoneal injection (50 mg/

kg potassium dichromate or sodium dichromate dihy

drate) produced significant increases in micronucleated

erythrocytes (De Flora et al. , 2006). NTP peripheral

### 22 Sodium Dichromate Dihydrate, NTP TR 546



### blood micronucleus studies conducted in B6C3F1,

BALB/c, and am3 -C57BL/6 mice with sodium

dichromate dihydrate administered in drinking water

for 3 months gave mixed results (NTP, 2007a); sig

nificant increases in micronucleated erythrocytes were

seen only in am3 -C57BL/6 mice. Kirpnick-Sobol et

al. (2006) reported that exposure of pregnant mice

(C57BL/6J p un 

### /p un 

### ) to either potassium dichromate

(Cr VI; 62.5 or 125.0 mg/L) or chromium (III) chloride

(1,875 or 3,750 mg/L) in drinking water during gesta

tional days 10 to 20 resulted in significant increases in

the frequencies of large-scale DNA deletions in their

pups examined at 20 days of age. Kirpnick-Sobol et al.

(2006) reported that in embryos exposed to Cr III, signif

icant increases in DNA deletions were seen at threefold

lower chromium tissue concentrations than in embryos

exposed to Cr VI. They concluded that, although only

small amounts of Cr III were absorbed, Cr III was highly

effective at inducing DNA damage. 

# S t u d y 

# R a tion a le

The California Congressional Delegation, California

Environmental Protection Agency, and the California

Department of Health Services nominated Cr VI for

toxicity and carcinogenicity testing because of concerns

over its presence in drinking water source supplies, its

potential health effects, including carcinogenicity, and

the lack of adequate carcinogenicity studies of ingested

Cr VI. The results of 3-month toxicity studies of Cr

VI administered in drinking water to F344/N rats and

B6C3F1, BALB/c, and am3 -C57BL/6 mice as sodium

dichromate dihydrate have been published (NTP, 2007a).

Hexavalent chromium is a human carcinogen by inhala

tion exposure, but available data are inadequate to evalu

ate its carcinogenic potential when ingested in drinking

water. This Technical Report summarizes the results

of 2-year toxicology and carcinogenesis drinking water

studies conducted in male and female F344/N rats and

B6C3F1 mice.

### 23



# P r o cur e m ent

a nd 

# C harac te r iz a tion

o f 

# S odi um 

# D i chr o ma te 

# D i hy d ra te

Sodium dichromate dihydrate was obtained from Aldrich

Chemical Company (Milwaukee, WI) in two lots. The

two lots were combined at the analytical chemistry

laboratory, Battelle Memorial Institute (Columbus, OH),

and assigned a new lot number (062001) for use in the

2-year studies. Identity and purity analyses were con

ducted by the analytical chemistry laboratory, the study

laboratory (Southern Research Institute, Birmingham,

AL), Galbraith Laboratories, Inc. (Knoxville, TN), and

Elemental Analysis Corp. (Lexington, KY) (Appendix

F). Reports on analyses performed in support of the

sodium dichromate dihydrate studies are on file at the

National Institute of Environmental Health Sciences.

Lot 062001, an orange crystalline solid, was identified

as sodium dichromate dihydrate by the analytical chem

istry laboratory using X-ray diffraction, by the analyti

cal chemistry laboratory and by Galbraith Laboratories,

Inc., using elemental analysis by inductively coupled

plasma

- atomic emission spectroscopy (ICP

- AES), and

by Elemental Analysis Corp. using proton-induced X

- ray

emission spectroscopy (PIXE). Elemental analyses for

chromium and sodium by ICP-AES were in agreement

with the theoretical values for sodium dichromate dihy

drate, and PIXE indicated the absence of significant

metallic impurities.

The moisture content of lot 062001 was determined by

Galbraith Laboratories, Inc., using Karl Fischer titra

tion. The purity of lot 062001 was determined by the

analytical chemistry laboratory using differential scan

ning calorimetry (DSC), titration of the dichromate ion

with sodium thiosulfate and potassium ferrocyanide, and

speciation of the chromium ions using liquid chromatog

raphy-inductively coupled plasma-mass spectrometry

(LC

- ICP-MS) and by the study laboratory using poten

tiometric titration with sodium thiosulfate. Karl Fischer

titration indicated a water content of 11.62%, which is

in agreement with the theoretical value of 12.09%. DSC

indicated a purity of 99.73% ± 0.15%. Titration with sodium thiosulfate by the analytical chemistry labora

tory indicated a purity of 99.7% ± 0.1%. Titration with

sodium thiosulfate by the study laboratory indicated

purities of 101% and 102% relative to a frozen refer

ence standard of the same lot. Titration with potassium

ferrocyanide indicated a purity of 103.1% ± 0.2%.

LC

- ICP

- MS indicated that the concentration of Cr III,

if present, was less than 0.1%. The overall purity of

lot 062001 was determined to be greater than 99.7%.

To ensure stability, the bulk chemical was stored at

room temperature, protected from light in amber glass

bottles.

Periodic reanalyses of the bulk chemical were performed

by the study laboratory using potentiometric titration as

described for the purity assays; no degradation of the

bulk chemical was detected.



# P r ep ara tion a nd 

# A n a l ys i s

o f 

# D o s e 

# F o rmu l a tion s

The dose formulations were prepared approximately

every 2 weeks by mixing sodium dichromate dihydrate

with tap water (Table F1). Formulations were stored in

NALGENE ® 

### containers at room temperature for up to

42 days.

Stability studies of a 41.8 μg/mL dose formulation

were performed by the analytical chemistry laboratory

using ion chromatography. Stability was confirmed for

at least 42 days for dose formulations stored in sealed

NALGENE ® 

### containers, protected from light, at tem

peratures up to room temperature and for at least 7 days

when stored in drinking water bottles under simulated

animal room conditions.

Periodic analyses of the dose formulations of sodium

dichromate dihydrate were conducted by the study

laboratory using ultraviolet/visible/near infrared spec

troscopy (350 to 390 nm). The dose formulations were

analyzed approximately every 10 weeks (Table F2). Of

the dose formulations analyzed, all 44 for rats and all

84 for mice were within 10% of the target concentra



# MATERIALS AND METHODS 23

### 24 Sodium Dichromate Dihydrate, NTP TR 546



### tions. Animal room samples and unused carboy storage

samples of these dose formulations were also analyzed;

all 16 animal room samples for rats and 34 of 35 animal

room samples for mice were within 10% of the target

concentrations. Fourteen of 16 carboy samples for rats

and 33 of 35 carboy samples for mice were within 10%

of the target concentrations.

The sodium dichromate dihydrate dosed water used in

these studies was slightly acidic. Based on an equilibrium

constant of 50, dichromate predominates at the highest

exposure concentration and the chromate:dichromate

ratio approaches 1 at the lowest exposure concentration.

These ratios would be obtained when the starting mate

rial was a chromate or dichromate salt.



# E xpo sur e 

# C on c ent ra tion



# R

a tion a le f o r 

# R a t s a nd 

# M i c e

The 2-year studies were designed after an NTP pub

lic meeting on hexavalent chromium held on July 24,

2002, at the National Institute of Environmental Health

Sciences in Research Triangle Park, NC, to consider the

results of the prechronic studies and recommendations

from the panel of scientific experts convened at this

meeting (NTP, 2006). Exposure concentrations were

selected based on these public discussions and careful

review of the data from the 3-month toxicity studies.

Based on source water concentrations, an additional low

exposure concentration group was added to the 2-year

studies to provide a concentration that was closer to con

centrations to which humans might be exposed through

the drinking water. A wider spacing of the exposure

concentrations was also recommended to extend the

dose

- response curve. The highest exposure concentra

tion in rats and mice was limited by toxicity observed in

the 3-month studies. In the 3-month studies, reductions

in body weight and water consumption and increased

incidences of ulcers in the glandular stomach were

observed in male and female rats exposed to 1,000 mg

sodium dichromate dihydrate/L. Based on these consid

erations, the exposure concentrations of total chromium

recommended were 0, 5, 20, 60, or 180 mg/L for male

and female rats. These exposure concentrations are

equivalent to 0, 14.3, 57.3, 172, or 516 mg/L sodium

dichromate dihydrate. In mice, significant reductions

in body weight and water consumption were observed

in males exposed to 500 or 1,000 mg/L and females

exposed to 1,000 mg/L. Based on these considerations,

the exposure concentrations of total chromium recom

mended were 0, 5, 10, 30, or 90 mg/L for male mice

and 0, 5, 20, 60, or 180 mg/L for female mice. These

exposure concentrations are equivalent to 0, 14.3, 28.6,

85.7, or 257.4 mg/L and 0, 14.3, 57.3, 172, or 516 mg/L

sodium dichromate dihydrate for males and females,

respectively.



# 2-Y e ar 

# S t u die s



## Study Design

Groups of 50 male and 50 female core study rats and

mice were exposed to sodium dichromate dihydrate in

drinking water at concentrations of 0, 14.3, 57.3, 172,

or 516 mg/L (rats and female mice) or 0, 14.3, 28.6,

85.7, or 257.4 mg/L (male mice) for 105 to 106 weeks.

Groups of 40 male special study rats and 40 female spe

cial study mice were exposed to the same concentrations

for up to 53 weeks, and these animals were used for

clinical pathology (Appendix E) and for tissue distribu

tion (Appendix J) studies. Groups of 12 male clinical

pathology rats and 16 female clinical pathology mice

were exposed to the same concentrations for 22 days.



## Source and Specification of Animals

Male and female F344/N rats and B6C3F1 mice were

obtained from Taconic Farms, Inc. (Germantown, NY),

for use in the 2

- year studies. Core study rats and mice

were quarantined for 14 days before the beginning of

the studies. Five male and five female rats and mice

were randomly selected for parasite evaluation and gross

observation of disease. Rats and mice were approxi

mately 6 to 7 weeks old at the beginning of the studies.

The health of the animals was monitored during the

studies according to the protocols of the NTP Sentinel

Animal Program (Appendix I).



## Animal Maintenance

Core study rats were housed three (males) or five

(females) per cage, and core study mice were housed one

(males) or five (females) per cage. Feed and water were

available ad libitum . Water consumption was measured

weekly for the first 13 weeks and then every 4 weeks

for a 7-day period each time. Cages were changed once

(male mice) or twice weekly, and cages and racks were

rotated every 2 weeks. Further details of animal mainte

nance are given in Table 1. Information on feed compo

sition and contaminants is provided in Appendix H.

### Sodium Dichromate Dihydrate, NTP TR 546 25



## Clinical Examinations and Pathology

All animals were observed twice daily and were weighed

initially, weekly for the first 13 weeks, at 4-week inter

vals thereafter, and at the end of the studies. Clinical

findings were recorded at 4-week intervals beginning

at week 5.

Hematology and clinical chemistry (rats only) evalua

tions were performed on up to 10 clinical pathology rats

on day 4, clinical pathology rats and mice on day 22, and

special study rats and mice at 3, 6, and 12 months. At

these time points, rats and mice were anesthetized with

CO

2 

### /O

2 

### , and blood was taken from the retroorbital sinus.

Clinical pathology animals were removed from the study

after blood collection on day 22. Blood samples for

hematology analyses were placed in tubes containing

potassium EDTA as the anticoagulant; blood samples

for the clinical chemistry analyses were placed in tubes

not containing an anticoagulant, allowed to clot at room

temperature, and centrifuged, and the serum was sepa

rated. Slides for hematology were stained with a modi

fied Wright’s stain using an Ames HEMATEK ® 

### slide

stainer (Miles Laboratory, Elkhart, IN), and hematology

determinations including erythrocyte and leukocyte

counts, hemoglobin concentration, hematocrit, mean cell

volume, mean cell hemoglobin, and mean cell concen

tration were performed on an ADVIA tm 

### 120 automated

hematology analyzer (Bayer, Inc., Tarrytown, NY)

with reagents provided by Bayer, Fisher Scientific

(Norcross, GA), or Sigma Diagnostics (St. Louis, MO).

Nucleated erythrocyte counts were determined by blood

smears stained with neutral Wright-Giemsa stain and

microscopically examined. Reticulocyte counts were

obtained through sphering of blood smears with a

zwitterionic agent and stained with an Oxazine dye;

blood smears stained with New Methylene Blue Stain

(Accustain Reticulocyte Stain; Sigma Diagnostics)

were examined microscopically for the determination

of manual reticulocyte counts. Clinical chemistry

measurements were performed on a Hitachi 911 ran

dom access automated chemistry analyzer (Boehringer

Mannheim, Indianapolis, IN) using reagents from Roche

Sigma Diagnostics, Trinity Biotech (Overland, MO), or

Diagnostic Chemicals, Ltd. (Oxford, CT).

Complete necropsies and microscopic examinations were

performed on all core study rats and mice. 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, trimmed and processed,

embedded in paraffin, sectioned to a thickness of 4 to

6 μm, and stained with hematoxylin and eosin for micro

scopic examination. For all paired organs (e.g., adrenal

gland, kidney, ovary), samples from each organ were

examined. Tissues examined microscopically are listed

in Table 1. During the audit of the pathology specimens

for the rat and mouse studies, the residual wet tissues of

the gastrointestinal tract from male and female rats and

mice from all groups were examined to ensure that the

entire gastrointestinal tract was adequately opened. Any

untrimmed potential lesions were collected for micro

scopic evaluation.

Microscopic evaluations were completed by the study

laboratory pathologist, and the pathology data were

entered into the Toxicology Data Management System

(TDMS). The 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

evaluated slides of all neoplasms and all potential target

organs for all animals which included the glandular

stomach, small intestine (duodenum, ileum, jejunum),

large intestine (cecum, colon), liver, oral mucosa, and

tongue of rats and the forestomach, glandular stomach,

small intestine (duodenum, ileum, jejunum), and large

intestine (cecum, colon) of mice. In addition, slides

for all animals were reviewed for specific lesions in the

bone marrow, kidney, pancreatic and mesenteric lymph

nodes, and salivary glands of rats and the bone marrow,

kidney, pancreatic and mesenteric lymph nodes, pan

creas, spleen, thymus, and urinary bladder of mice.

The oral mucosa and tongue are not protocol-required

tissues, and as such, only lesions that are observed

grossly in these sites are routinely evaluated histo

logically. Because the gross lesions observed in the oral

mucosa were diagnosed as neoplasms, the oral mucosa

(present on slides of the three standard sections of the

nasal cavity required to be evaluated for each study)

from all male and female rats and mice in all expo

sure concentration groups was evaluated for neoplastic

and nonneoplastic lesions by the quality assessment

and Pathology Working Group (PWG) pathologists.

Histologic sections of the tongue were prepared for all

male and female rats and mice in all exposure concentra

tion groups and were evaluated for neoplastic and non

neoplastic lesions.

### 26 Sodium Dichromate Dihydrate, NTP TR 546



### The quality assessment report and the reviewed slides

were submitted to the NTP PWG chairperson, who

reviewed the selected tissues and addressed any incon

sistencies in the diagnoses made by the laboratory and

quality assessment pathologists. Representative histopa

thology slides containing examples of lesions related to

chemical administration, examples of disagreements in

diagnoses between the laboratory and quality assessment

pathologists, or lesions of general interest were pre

sented by the chairperson to the PWG for review. The

PWG consisted of the quality assessment pathologist

and other pathologists experienced in rodent toxicologic pathology. When the PWG consensus differed from the

opinion of the laboratory pathologist, the diagnosis was

changed. Final diagnoses for reviewed lesions represent

a consensus between the laboratory pathologist, review

ing pathologist(s), and the PWG. Details of these review

procedures have been described, in part, by Maronpot

and Boorman (1982) and Boorman et al. (1985). For

subsequent analyses of the pathology data, the decision

of whether to evaluate the diagnosed lesions for each

tissue type separately or combined was generally based

on the guidelines of McConnell et al. (1986).

T ab le 

### 1

Experimental Design and Materials and Methods in the 2-Year Drinking Water Studies

of Sodium Dichromate Dihydrate

Study Laboratory

Southern Research Institute (Birmingham, AL)



### Strain and Species

F344/N rats

B6C3F1 mice



### Animal Source

Taconic Farms, Inc. (Germantown, NY)



### Time Held Before Studies

14 days



### Average Age When Studies Began

6 to 7 weeks



### Date of First Exposure

Rats: October 2, 2002

Mice: September 4, 2002



### Duration of Exposure

105 to 106 weeks



### Date of Last Exposure

Rats: October 7, 2004

Mice: September 9, 2004



### Necropsy Dates

Rats: September 29 to October 7, 2004

Mice: September 1 to 9, 2004



### Average Age at Necropsy

110 to 112 weeks



### Size of Study Groups

Core study: 50 males and 50 females

Clinical pathology study: 12 male rats and 16 female mice

Special study: 40 male rats and 40 female mice

### Sodium Dichromate Dihydrate, NTP TR 546 27



### T ab le 

### 1

Experimental Design and Materials and Methods in the 2-Year Drinking Water Studies

of Sodium Dichromate Dihydrate

Method of Distribution

Animals were distributed randomly into groups of approximately equal initial mean body weights.



### Animals per Cage

Rats: 3 (males) or 5 (females)

Mice: 1 (males) or 5 (females)



### Method of Animal Identification

Tail tattoo



### Diet

Irradiated NTP-2000 wafers (Zeigler Brothers, Inc., Gardners, PA), available ad libitum , changed weekly



### Water

Tap water (Birmingham municipal supply) via amber glass bottles (Wheaton Science Products, Millville, NJ) with Teflon ® -lined plastic screw

caps fitted with stainless steel, double-ball sipper tubes, available ad libitum , changed twice weekly



### Cages

Solid-bottom polycarbonate (Lab Products, Maywood, NJ), changed once (male mice) or twice weekly



### Bedding

Heat-treated, irradiated hardwood chips (P.J. Murphy Forest Products, Inc., Montville, NJ), changed once (male mice) or twice weekly



### Rack Filters

Reemay ® spun-bonded polyester (Andico, Birmingham, AL), changed every 2 weeks



### Racks

Stainless steel (Lab Products, Maywood, NJ), changed and rotated every 2 weeks



### Animal Room Environment

Temperature: 72° ± 3° F

Relative humidity: 50% ± 15%

Room fluorescent light: 12 hours/day

Room air changes: 10/hour



### Exposure Concentrations

Rats: 0, 14.3, 57.3, 172, and 516 mg/L in drinking water, available ad libitum

Mice: 0, 14.3, 28.6, 85.7, and 257.4 mg/L (males) or 0, 14.3, 57.3, 172, and 516 mg/L (females) in drinking water, available ad libitum



### Type and Frequency of Observation

Observed twice daily; core study animals were weighed initially, weekly for the first 13 weeks, at 4-week intervals thereafter, and at the end of

the studies; clinical findings for core study animals were recorded at 4-week intervals beginning at week 5. Water consumption by core study

animals was recorded weekly for the first 13 weeks and every 4 weeks thereafter with each water consumption measurement covering a 7-day

period.



### Method of Sacrifice

Carbon dioxide asphyxiation



### Necropsy

Necropsies were performed on all core study animals.

### 28 Sodium Dichromate Dihydrate, NTP TR 546



### T able 

### 1

Experimental Design and Materials and Methods in the 2-Year Drinking Water Studies

of Sodium Dichromate Dihydrate

Clinical Pathology

Blood was collected from the retroorbital sinus of clinical pathology male rats and female mice on days 4 (rats only) and 22 and from special

study male rats and female mice at 3, 6, and 12 months for hematology and clinical chemistry (rats only).

Hematology: hematocrit; hemoglobin concentration; erythrocyte, reticulocyte, and platelet counts; erythrocyte and platelet morphology; mean

cell volume; mean cell hemoglobin; mean cell hemoglobin concentration; and leukocyte count and differentials

Clinical chemistry: urea nitrogen, creatinine, total protein, albumin, alanine aminotransferase, alkaline phosphatase, creatine kinase, sorbitol

dehydrodrogenase, bile acids



### Histopathology

Complete histopathology was performed on all core study rats and mice. In addition to gross lesions and tissue masses, the following tissues

were examined: adrenal gland, bone (with marrow), brain, clitoral gland, esophagus, eye, gallbladder (mice only), Harderian gland, heart, large

intestine (cecum, colon, rectum), small intestine (duodenum, jejunum, ileum), kidney, liver, lung, lymph nodes (mandibular and mesenteric),

mammary gland, nose, ovary, pancreas, parathyroid gland, pituitary gland, preputial gland, prostate gland, salivary gland, skin, spleen, stomach

(forestomach and glandular), testis (with epididymis and seminal vesicle), thymus, thyroid gland, tongue, trachea, urinary bladder, and uterus.



### Chromium Tissue Distribution

On days 4 and 11 and at 6 and 12 months, 10 special study rats and 8 or 10 special study mice were removed from treatment; five rats and

all mice were placed in metabolism cages for 48 hours for urine and feces collection. Urine volume, feces weight, and urine creatinine

concentration were determined. All special study rats and mice were anesthetized with CO

2 /O

2 , and following blood collection for clinical

pathology, the liver, kidneys, and stomach (glandular and nonglandular) were collected. Urine, feces, and tissues were frozen until further

analysis.



# S t a t i st ical 

# M e t hod s



## Survival Analyses

The probability of survival was estimated by the prod

uct-limit procedure of Kaplan and Meier (1958) and is

presented in the form of graphs. Animals found dead

of other than natural causes or missing were censored

from the survival analyses; animals dying from natural

causes were not censored. Statistical analyses for pos

sible 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

are presented in Tables A1, A4, B1, B4, C1, C4, D1,

and D4 as the numbers of animals bearing such lesions

at a specific anatomic site and the numbers of animals

with that site examined microscopically. For calculation

of statistical significance, the incidences of most neo

plasms (Tables A2, B2, C2, and D2) and all nonneoplas

tic 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., Harderian gland,

intestine, mammary gland, and skin) 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 A2, B2, C2, and D2

also give the survival-adjusted neoplasm rate for each

group and each site-specific neoplasm. This survivaladjusted rate (based on the Poly

- 3 method described

below) accounts for differential mortality by assigning

a reduced risk of neoplasm, proportional to the third

power of the fraction of time on study, only to sitespecific, lesion-free animals that do not reach terminal

sacrifice.



## Analysis of Neoplasm

and Nonneoplastic Lesion Incidences

The Poly

- k test (Bailer and Portier, 1988; Portier and

Bailer, 1989; Piegorsch and Bailer, 1997) was used to

assess neoplasm and nonneoplastic lesion prevalence.

This test is a survival-adjusted quantal-response proce

dure that modifies the Cochran-Armitage linear trend

test to take survival differences into account. More

specifically, this method modifies the denominator in

the quantal estimate of lesion incidence to approximate

more closely the total number of animal years at risk.

### Sodium Dichromate Dihydrate, NTP TR 546 29



### For analysis of a given site, each animal is assigned a

risk weight. This value is one if the animal had a lesion

at that site or if it survived until terminal sacrifice; if

the animal died prior to terminal sacrifice and did not

have a lesion at that site, its risk weight is the fraction

of the entire study time that it survived, raised to the kth

power.

This method yields a lesion prevalence rate that depends

only upon the choice of a shape parameter for a Weibull

hazard function describing cumulative lesion incidence

over time (Bailer and Portier, 1988). Unless otherwise

specified, a value of k=3 was used in the analysis of sitespecific lesions. This value was recommended by Bailer

and Portier (1988) following an evaluation of neoplasm

onset time distributions for a variety of site-specific neo

plasms in control F344 rats and B6C3F1 mice (Portier

et al., 1986). Bailer and Portier (1988) showed that the

Poly

- 3 test gave valid results if the true value of k was

anywhere in the range from 1 to 5. A further advantage

of the Poly

- 3 method is that it does not require lesion

lethality assumptions. Variation introduced by the use

of risk weights, which reflect differential mortality,

was accommodated by adjusting the variance of the

Poly

- 3 statistic as recommended by Bieler and Williams

(1993).

Tests of significance included pairwise comparisons of

each exposed group with controls and a test for an over

all exposure-related trend. Continuity-corrected Poly

- 3

tests were used in the analysis of lesion incidence, and

reported P values are one sided. The significance of

lower incidences or decreasing trends in lesions is rep

resented as 1–P with the letter N added (e.g., P=0.99 is

presented as P=0.01N).



## Analysis of Continuous Variables

Two approaches were employed to assess the signifi

cance of pairwise comparisons between exposed and

control groups in the analysis of continuous variables.

Body weight data, which historically have approximately

normal distributions, were analyzed with the parametric

multiple comparison procedures of Dunnett (1955)

and Williams (1971, 1972). Hematology and clinical

chemistry data, which have typically skewed distribu

tions, were analyzed using the nonparametric multiple

comparison methods of Shirley (1977) (as modified by

Williams, 1986) and Dunn (1964). Jonckheere’s test

(Jonckheere, 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). Prior to statistical analysis,

extreme values identified by the outlier test of Dixon and

Massey (1957) were examined by NTP personnel, and

implausible values were eliminated from the analysis.

Average severity values were analyzed for significance

with the Mann-Whitney U test (Hollander and Wolfe,

1973).



## Historical Control Data

The concurrent control group represents the most valid

comparison to the treated groups and is the only control

group analyzed statistically in NTP bioassays. However,

historical control data are often helpful in interpret

ing potential treatment-related effects, particularly for

uncommon or rare neoplasm types. For meaningful

comparisons, the conditions for studies in the historical

database must be generally similar. One significant fac

tor affecting the background incidence of neoplasms at a

variety of sites is diet. In 1995, the NTP incorporated a

new diet (NTP

- 2000) that contains less protein and more

fiber and fat than the NIH

- 07 diet previously used in

toxicity and carcinogenicity studies (Rao, 1996, 1997).

The NTP historical database contains all studies that use

the NTP

- 2000 diet with histopathology findings com

pleted within the most recent 5-year period. A second

potential source of variability is route of administration.

In general, the historical database for a given study will

include studies using the same route of administration,

and the overall incidences of neoplasms for all routes of

administration are included for comparison, including

the present study.



# Q ua lit y 

# A ssura n c e 

# M et h od s

The 2

- year studies were conducted in compliance 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 covered completeness and accuracy of the pathol

ogy data, pathology specimens, final pathology tables,

and a draft of this NTP Technical Report. Audit proce

dures and findings are presented in the reports and are

on file at NIEHS. The audit findings were reviewed and

assessed by NTP staff, and all comments were resolved

or otherwise addressed during the preparation of this

Technical Report.

### 30 Sodium Dichromate Dihydrate, NTP TR 546

### 31



# RESULTS

R

a t s



# 2-Y e ar 

# S t u d y



## Survival

Estimates of 2-year survival probabilities for male and

female rats are shown in Table 2 and in the KaplanMeier survival curves (Figure 1). Survival of exposed

groups was similar to that of the control groups.



## Body Weights, Water and Compound

Consumption, and Clinical Findings

Mean body weights of the 14.3, 57.3, and 172 mg/L

groups of male and female rats were generally similar

to those of the control groups throughout the study

(Tables 3 and 4; Figure 2). Mean body weights of

516 mg/L males and females were less than those of

controls throughout the study and by the end of the study

were 88% and 89% that of the respective controls. The lower body weights were partly attributed to poor palat

ability of the dosed water and consequent reductions

in water consumption rather than direct toxic effects

of sodium dichromate dihydrate exposure. Water con

sumption by 172 and 516 mg/L rats was less than that

by the controls throughout the study (Tables G1 and

G2). Decreases were evident from the first week of the

study and continued until terminal sacrifice. During the

second year of the study, the average water consump

tion was reduced by 15% and 22% and by 15% and 27%

that of the controls in the 172 and 516 mg/L male and

female rats, respectively. Drinking water concentrations

of 14.3, 57.3, 172, or 516 mg/L resulted in average daily

doses of approximately 0.6, 2.2, 6, or 17 mg sodium

dichromate dihydrate/kg body weight for male rats and

0.7, 2.7, 7, or 20 mg/kg for female rats. No clinical

findings were attributed to sodium dichromate dihydrate

exposure.

### 32 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### 2

Survival of Rats in the 2-Year Drinking Water Study of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Male

Animals initially in study 50 50 50 50 50

Missing a 0 0 1 0 1

Moribund 16 15 16 9 16

Natural deaths 6 5 3 5 4

Animals surviving to study termination 28 30 30 36 29

Percent probability of survival at end of study b 56 60 61 72 59

Mean survival (days) c 695 670 672 692 694

Survival analysis d P=0.904N P=1.000N P=1.000N P=0.221N P=1.000N



### Female

Animals initially in study 50 50 50 50 50

Moribund 12 15 9 10 18

Natural deaths 5 3 9 4 1

Animals surviving to study termination 33 e 32 32 36 31

Percent probability of survival at end of study 66 64 64 72 62

Mean survival (days) 696 691 694 686 685

Survival analysis P=0.748 P=0.959 P=0.965 P=0.806N P=0.745

a Censored from survival analyses

b Kaplan-Meier determinations

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 group columns. A negative trend or lower mortality in an exposed group is indicated by N

.

e Includes one animal that died during the last week of the study

### Sodium Dichromate Dihydrate, NTP TR 546 33



### F i gur e 

### 1

Kaplan-Meier Survival Curves for Male and Female Rats Exposed to Sodium Dichromate Dihydrate

in Drinking Water for 2 Years Sodium Dichromate Dihydrate, NTP TR 546 33

### 34 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### 3

Mean Body Weights and Survival of Male Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

Days 0 mg/L 14.3 mg/L 57.3 mg/L

on Av. Wt. No. of Av. Wt. Wt. (% of No. of Av. Wt. Wt. (% of No. of

Study (g) Survivors (g) controls) Survivors (g) controls) Survivors

1 118 50 117 99 50 117 99 50

8 151 50 149 99 50 146 97 50

15 185 50 183 99 50 181 98 50

22 218 50 215 99 50 213 98 50

29 243 50 240 99 50 239 99 50

36 261 50 257 99 50 257 99 50

43 275 50 271 99 50 272 99 50

50 289 50 286 99 50 285 99 50

57 305 50 301 99 50 302 99 50

64 317 50 312 99 50 313 99 50

71 334 50 329 98 50 331 99 50

78 345 50 340 99 50 339 98 50

85 351 50 345 98 50 348 99 50

113 387 50 381 98 50 383 99 50

141 410 50 404 99 50 407 99 50

169 434 50 427 98 50 431 99 50

197 451 50 443 98 50 448 99 50

225 468 50 458 98 50 464 99 50

253 480 50 471 98 50 477 99 50

281 488 50 478 98 50 483 99 49

309 490 50 485 99 50 488 100 49

337 501 50 495 99 48 497 99 48

365 511 50 502 98 47 505 99 48

393 515 50 507 98 47 512 99 48

421 523 50 515 98 47 519 99 48

449 524 50 515 98 47 519 99 48

477 525 50 516 98 45 518 99 48

505 525 48 517 98 45 520 99 46

533 530 47 519 98 45 525 99 45

561 532 47 518 97 44 525 99 44

589 531 46 515 97 42 522 98 43

617 529 45 519 98 40 519 98 40

645 526 44 517 98 38 520 99 36

673 513 41 515 100 36 517 101 32

701 515 32 503 98 33 514 100 31



### Mean for weeks

1-13 261 257 99 257 99

14-52 457 449 98 453 99

53-101 523 514 98 518 99

### Sodium Dichromate Dihydrate, NTP TR 546 35



### T ab le 

### 3

Mean Body Weights and Survival of Male Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

Days 172 mg/L 516 mg/L

on Av. Wt. Wt. (% of No. of Av. Wt. Wt. (% of No. of

Study (g) controls) Survivors (g) controls) Survivors

1 117 99 50 118 100 50

8 147 97 50 143 95 50

15 180 97 50 173 93 50

22 210 97 50 201 93 50

29 235 97 50 225 93 50

36 254 97 50 243 93 50

43 267 97 50 257 93 50

50 279 96 50 270 93 50

57 295 96 50 285 93 50

64 304 96 50 295 93 50

71 321 96 50 311 93 50

78 330 96 50 320 93 50

85 338 96 50 324 92 50

113 373 96 50 363 94 50

141 395 96 50 386 94 50

169 418 96 50 407 94 50

197 437 97 50 424 94 50

225 449 96 50 437 94 50

253 462 96 50 447 93 50

281 469 96 50 454 93 50

309 477 97 50 461 94 50

337 486 97 50 468 94 50

365 490 96 50 475 93 50

393 496 96 50 479 93 50

421 503 96 49 485 93 50

449 504 96 49 484 92 50

477 503 96 49 484 92 50

505 501 96 49 483 92 50

533 508 96 47 487 92 50

561 507 95 46 483 91 48

589 506 95 44 473 89 47

617 502 95 42 480 91 41

645 501 95 39 474 90 39

673 500 97 39 462 90 36

701 500 97 38 455 88 32



### Mean for weeks

1-13 252 97 243 94

14-52 441 96 427 94

53-101 502 96 477 91

### 36 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### 4

Mean Body Weights and Survival of Female Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

Days 0 mg/L 14.3 mg/L 57.3 mg/L

on Av. Wt. No. of Av. Wt. Wt. (% of No. of Av. Wt. Wt. (% of No. of

Study (g) Survivors (g) controls) Survivors (g) controls) Survivors

1 100 50 99 99 50 100 99 50

9 122 50 120 99 50 121 99 50

16 135 50 132 98 50 134 99 50

23 150 50 146 97 50 147 98 50

30 157 50 154 98 50 154 98 50

37 164 50 161 98 50 162 98 50

44 170 50 168 99 50 167 98 50

51 175 50 172 98 50 172 98 50

58 180 50 178 99 50 177 98 50

65 183 50 180 99 50 180 98 50

72 188 50 184 98 50 185 98 50

79 193 50 189 98 50 188 97 50

86 198 50 193 97 50 192 97 50

114 208 50 203 97 50 202 97 50

142 217 50 211 97 50 209 96 50

170 229 50 223 98 50 221 97 50

198 237 50 229 97 50 229 97 50

226 246 50 239 97 50 237 96 50

254 255 50 248 97 50 246 97 50

282 263 50 255 97 50 253 96 50

310 272 50 261 96 50 262 96 50

338 281 50 271 96 50 271 96 50

366 289 50 279 97 50 278 96 50

394 297 50 288 97 49 287 97 50

422 309 50 297 96 49 297 96 50

450 314 50 302 96 49 304 97 50

478 317 50 307 97 48 310 98 49

506 323 49 312 97 48 315 98 49

534 332 48 323 97 48 322 97 48

562 337 48 328 98 46 325 97 47

590 341 46 332 97 46 333 98 44

618 336 42 332 99 43 333 99 43

646 348 40 336 96 41 340 98 43

674 350 39 339 97 37 346 99 38

702 351 35 338 96 34 346 98 34



### Mean for weeks

1-13 163 160 98 160 98

14-52 245 238 97 237 96

53-101 326 316 97 318 98

### Sodium Dichromate Dihydrate, NTP TR 546 37



### T ab le 

### 4

Mean Body Weights and Survival of Female Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

Days 172 mg/L 516 mg/L

on Av. Wt. Wt. (% of No. of Av. Wt. Wt. (% of No. of

Study (g) controls) Survivors (g) controls) Survivors

1 99 99 50 99 98 50

9 119 98 50 115 94 50

16 131 97 50 129 95 50

23 145 97 50 144 96 50

30 153 97 50 152 97 50

37 161 98 50 159 97 50

44 166 98 50 165 97 50

51 171 97 50 170 97 50

58 175 97 50 175 97 50

65 178 97 50 178 97 50

72 183 98 50 182 97 50

79 186 97 50 186 96 50

86 192 97 50 190 96 50

114 201 97 50 199 96 50

142 206 95 50 207 95 50

170 218 95 50 215 94 50

198 226 95 50 222 94 50

226 235 96 50 230 94 50

254 242 95 50 237 93 50

282 248 94 50 242 92 50

310 256 94 50 248 91 50

338 265 94 50 254 90 50

366 272 94 50 263 91 50

394 279 94 49 268 90 50

422 290 94 49 275 89 50

450 296 94 48 281 89 50

478 302 95 48 284 90 48

506 308 95 47 290 90 47

534 318 96 46 298 90 47

562 319 95 45 300 89 46

590 325 95 42 307 90 42

618 326 97 40 314 93 40

646 333 96 39 315 90 40

674 337 96 37 318 91 36

702 340 97 36 312 89 35



### Mean for weeks

1-13 158 97 157 96

14-52 233 95 228 93

53-101 311 95 294 90

### 38 Sodium Dichromate Dihydrate, NTP TR 546



### F i gur e 

### 2

Growth Curves for Male and Female Rats Exposed

to Sodium Dichromate Dihydrate in Drinking Water for 2 Years

### Sodium Dichromate Dihydrate, NTP TR 546 39



## Hematology and Clinical Chemistry

The hematology and clinical chemistry data for male

rats are listed in Tables 5 and E1. An exposure con

centration-related erythrocyte microcytosis, evidenced

by decreased mean cell volumes, occurred on day 4 and

persisted throughout the study in the 172 and 516 mg/L

groups; the 57.3 mg/L group demonstrated minor changes

on day 22 and at months 3 and 6. In the 516 mg/L ani

mals, the severity of the microcytosis peaked with an

approximately 20% to 25% decrease in red cell size on

day 22 and at month 3. The severity of the microcytosis

ameliorated with time. For example, by 12 months, the

red cells of the 516 mg/L animals were only 5% smaller

than those of the controls. Changes in the mean cell

hemoglobin value mimicked the alterations in mean cell

volume and were a reflection of the smaller red cells.

Mean cell hemoglobin concentration demonstrated

small, exposure concentration-related decreases (less

than or equal to 10%) in the 172 and 516 mg/L animals.

The mean cell hemoglobin concentration decreases were

most severe on day 22 or at month 3; they ameliorated

with time.

An exposure-related anemia, evidenced by decreases

in hematocrit (instrument-derived), packed cell volume

(spun microhematocrit), hemoglobin, and erythrocyte

count values, developed by day 22 and affected the

57.3, 172, and 516 mg/L groups. The anemia was most

severe on day 22 (an approximate 30% decrease in the

516 mg/L group) but resolved with time. In fact, at

3 months, erythrocyte counts were increased, in contrast

to the lower hematocrit and hemoglobin values in the 516

mg/L group; the erythrocyte counts remained slightly

elevated (less than 10%) in the higher-exposed animals

out to the 12-month time point. The increased numbers of nucleated erythrocytes and/or reticulocytes in the 516

mg/L animals on day 22 and at month 3 were indicative

of an erythropoietic response. Microscopic evaluation

of the blood smears demonstrated increased poikilo

cytes, erythrocyte fragments/schizocytes, keratocytes,

erythrocyte hypochromia, and microcytes that suggested

increased erythrocyte injury or turnover. These changes

were most prominent in the higher-exposed animals on

day 22 and at month 3. Taken together, it appears that

the erythropoietic tissues were able to respond to the

anemia (also evidenced by slightly increased incidences

of bone marrow hyperplasia in the core study male rats

(0 mg/L, 4/50; 14.3 mg/L, 12/50; 57.3 mg/L, 7/49; 172

mg/L, 7/50; 516 mg/L, 6/49; Table A4), but there was

some ineffective erythropoiesis resulting in production

of increased numbers of smaller erythrocytes. This

effect was not observed at 6 or 12 months demonstrating

that, with time, the animals adapted to exposure.

Increases in serum alanine aminotransferase activity

occurred in the 57.3 mg/L or greater groups; how

ever, serum sorbitol dehydrogenase activities and bile

acid concentrations were unaffected (Table E1). The

severity of the serum alanine aminotransferase activ

ity increases peaked at 3 months (e.g., greater than a

twofold increase in the 516 mg/L group), stabilized,

and remained elevated at this level to the 12-month

time point. While there was an indication of a chronic

inflammatory process of minimal severity in the liver,

the lack of corroborating evidence in other markers of

liver injury suggests that the alanine aminotransferase

increases may have been related to enzyme induction in

the liver instead of increased hepatocellular membrane

leakage.

### 40 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### 5

Selected Hematology Data for Male Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate a



### 0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

n

Day 4 9 10 9 10 10

Day 22 10 10 10 10 10

Month 3 10 10 10 10 10

Month 6 10 10 10 10 10

Month 12 10 10 10 8 10

Hematocrit (auto) (%)

Day 4 37.5 ± 0.5 37.7 ± 0.5 36.4 ± 0.8 35.8 ± 0.7 37.0 ± 0.6

Day 22 46.5 ± 0.9 45.3 ± 0.5 44.2 ± 0.7 38.4 ± 0.8** 28.0 ± 0.6**

Month 3 45.1 ± 0.3 44.6 ± 0.4 44.7 ± 0.5 44.6 ± 0.5 43.0 ± 0.5**

Month 6 46.5 ± 0.3 46.7 ± 0.5 46.3 ± 0.5 46.5 ± 0.4 46.0 ± 0.3

Month 12 48.8 ± 0.6 48.0 ± 0.4 48.8 ± 0.7 49.3 ± 0.5 48.6 ± 0.4

Hematocrit (spun) (%)

Day 4 38.2 ± 0.5 b 38.4 ± 0.6 36.7 ± 0.9 36.4 ± 0.6 37.3 ± 0.6

Day 22 46.0 ± 1.1 44.4 ± 0.4 43.2 ± 0.6* 38.7 ± 0.6** 33.5 ± 0.8**

Month 3 45.3 ± 0.4 44.5 ± 0.3 44.5 ± 0.4 44.1 ± 0.5 41.0 ± 0.5**

Month 6 45.9 ± 0.4 45.7 ± 0.5 45.5 ± 0.4 45.5 ± 0.5 45.0 ± 0.3

Month 12 47.6 ± 0.5 46.6 ± 0.4 47.4 ± 0.5 47.7 ± 0.4 47.3 ± 0.4

Hemoglobin (g/dL)

Day 4 12.9 ± 0.2 13.0 ± 0.2 12.5 ± 0.3 12.3 ± 0.2 12.8 ± 0.2

Day 22 15.5 ± 0.3 15.1 ± 0.2 14.2 ± 0.2** 12.0 ± 0.3** 10.1 ± 0.2**

Month 3 15.1 ± 0.1 14.9 ± 0.1 14.9 ± 0.2 14.6 ± 0.2* 12.9 ± 0.2**

Month 6 15.2 ± 0.1 15.2 ± 0.2 15.0 ± 0.2 14.9 ± 0.1 14.5 ± 0.1**

Month 12 15.8 ± 0.2 15.4 ± 0.2 15.6 ± 0.2 15.6 ± 0.2 15.3 ± 0.1*

Erythrocytes (10 6 / μ L)

Day 4 6.75 ± 0.11 6.80 ± 0.10 6.67 ± 0.17 6.73 ± 0.11 6.98 ± 0.12

Day 22 7.80 ± 0.13 7.74 ± 0.15 8.06 ± 0.16 8.10 ± 0.14 6.21 ± 0.13**

Month 3 9.28 ± 0.05 9.24 ± 0.06 9.46 ± 0.11 9.75 ± 0.11** 10.93 ± 0.16**

Month 6 9.34 ± 0.06 9.43 ± 0.08 9.54 ± 0.11 9.71 ± 0.08** 10.15 ± 0.13**

Month 12 9.27 ± 0.10 9.17 ± 0.07 9.40 ± 0.12 9.61 ± 0.11 9.74 ± 0.08**

Reticulocytes (auto) (10 6 / μ L)

Day 4 0.62 ± 0.04 0.56 ± 0.04 0.50 ± 0.04 0.24 ± 0.02** 0.19 ± 0.02**

Day 22 0.38 ± 0.03 0.34 ± 0.02 0.38 ± 0.03 0.43 ± 0.04 0.63 ± 0.07**

Month 3 0.23 ± 0.01 0.24 ± 0.01 0.22 ± 0.01 0.21 ± 0.01 0.30 ± 0.01**

Month 6 0.24 ± 0.00 0.22 ± 0.01 0.22 ± 0.01 0.24 ± 0.01 0.24 ± 0.01

Month 12 0.23 ± 0.01 0.23 ± 0.01 0.24 ± 0.01 0.26 ± 0.02 0.23 ± 0.01

Reticulocytes (manual) (10 6 / μ L)

Day 4 0.30 ± 0.06 0.29 ± 0.03 0.29 ± 0.06 0.30 ± 0.03 0.27 ± 0.02

Day 22 0.32 ± 0.04 0.27 ± 0.03 0.30 ± 0.03 0.41 ± 0.05 0.52 ± 0.04**

Month 3 0.12 ± 0.02 0.14 ± 0.02 0.10 ± 0.02 0.11 ± 0.03 0.13 ± 0.02

Month 12 0.19 ± 0.02 0.18 ± 0.01 0.21 ± 0.02 022 ± 0.03 0.17 ± 0.01

Nucleated erythrocytes (10 3 / μ L)

Day 4 0.50 ± 0.17 b 0.60 ± 0.22 0.20 ± 0.13 b 0.50 ± 0.17 0.10 ± 0.10

Day 22 0.20 ± 0.13 0.20 ± 0.13 0.30 ± 0.15 0.30 ± 0.21 1.40 ± 0.22**

Month 3 0.20 ± 0.13 0.40 ± 0.22 0.30 ± 0.21 0.20 ± 0.13 0.00 ± 0.00

Month 6 0.30 ± 0.15 0.10 ± 0.10 0.20 ± 0.13 0.10 ± 0.10 0.40 ± 0.22

Month 12 0.30 ± 0.21 0.30 ± 0.21 0.10 ± 0.10 0.38 ± 0.26 0.10 ± 0.10

Mean cell volume (fL)

Day 4 55.6 ± 0.3 55.5 ± 0.3 54.6 ± 0.3 53.3 ± 0.1** 53.0 ± 0.2**

Day 22 59.5 ± 0.4 58.6 ± 0.5 54.9 ± 0.5** 47.4 ± 0.4** 45.0 ± 0.7**

Month 3 48.6 ± 0.2 48.3 ± 0.2 47.3 ± 0.2** 45.7 ± 0.2** 39.2 ± 0.6**

Month 6 49.8 ± 0.1 49.5 ± 0.1 48.6 ± 0.1** 47.8 ± 0.2** 45.4 ± 0.5**

Month 12 52.6 ± 0.2 52.4 ± 0.2 51.9 ± 0.3 51.4 ± 0.3** 49.9 ± 0.2**

### Sodium Dichromate Dihydrate, NTP TR 546 41



### T ab le 

### 5

Selected Hematology Data for Male Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

n

Day 4 9 10 9 10 10

Day 22 10 10 10 10 10

Month 3 10 10 10 10 10

Month 6 10 10 10 10 10

Month 12 10 10 10 8 10

Mean cell hemoglobin (pg)

Day 4 19.1 ± 0.1 19.1 ± 0.1 18.7 ± 0.1* 18.3 ± 0.1** 18.4 ± 0.1**

Day 22 19.8 ± 0.1 19.5 ± 0.2 17.7 ± 0.2** 14.8 ± 0.2** 16.3 ± 0.5**

Month 3 16.2 ± 0.1 16.2 ± 0.1 15.7 ± 0.0** 15.0 ± 0.1** 11.9 ± 0.3**

Month 6 16.3 ± 0.1 16.1 ± 0.1 15.7 ± 0.1** 15.3 ± 0.1** 14.3 ± 0.2**

Month 12 17.0 ± 0.1 16.8 ± 0.1 16.6 ± 0.1* 16.2 ± 0.1** 15.7 ± 0.1**

Mean cell hemoglobin concentration (g/dL)

Day 4 34.4 ± 0.2 34.4 ± 0.2 34.3 ± 0.2 34.4 ± 0.2 34.7 ± 0.2

Day 22 33.3 ± 0.1 33.3 ± 0.1 32.2 ± 0.2 31.2 ± 0.2** 36.2 ± 0.8

Month 3 33.4 ± 0.1 33.5 ± 0.2 33.2 ± 0.1 32.7 ± 0.1** 30.2 ± 0.3**

Month 6 32.7 ± 0.1 32.5 ± 0.1 32.3 ± 0.1* 32.1 ± 0.1** 31.6 ± 0.2**

Month 12 32.3 ± 0.2 32.1 ± 0.3 32.0 ± 0.2 31.6 ± 0.2* 31.5 ± 0.2*

* Significantly different (P # 0.05) from the control group by Dunn’s or Shirley’s test

** P # 0.01

a Mean ± standard error. Statistical tests were performed on unrounded data.

b n=10

### 42 Sodium Dichromate Dihydrate, NTP TR 546



## Pathology and Statistical Analyses

This section describes the statistically significant or

biologically noteworthy changes in the incidences of

mononuclear cell leukemia and neoplasms or non

neoplastic lesions of the oral cavity (oral mucosa and

tongue), liver, small intestine (duodenum), mesenteric

lymph node, pancreatic lymph node, salivary gland,

pancreas, and adrenal medulla. Summaries of the

incidences of neoplasms and nonneoplastic lesions,

statistical analyses of primary neoplasms that occurred

with an incidence of at least 5% in at least one ani

mal 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.

Oral Cavity (Oral Mucosa and Tongue): Exposure to

sodium dichromate dihydrate resulted in the develop

ment of neoplasms of the squamous epithelium that lines

the oral mucosa and tongue. The incidences of squamous

cell carcinoma in the oral mucosa of 516 mg/L male and

female rats were significantly greater than those in the

controls (Tables 6, A2, and B2). None were seen in con

current or historical controls for drinking water studies.

Squamous cell carcinomas were also observed in the

oral mucosa of two 172 mg/L female rats and exceeded

the historical control ranges for drinking water studies

and for all routes of administration. One squamous cell

carcinoma of the tongue occurred in a 14.3 mg/L male

and one in a 172 mg/L female. A squamous cell papil

loma of the oral mucosa occurred in one 516 mg/L male, and a squamous cell papilloma of the tongue occurred

in one 516 mg/L male. One control and one 14.3 mg/L

female had squamous cell papillomas of the tongue.

The incidences of squamous cell papilloma or squamous

cell carcinoma (combined) of the oral mucosa or tongue

of 516 mg/L male and female rats were significantly

greater than those in the controls (Table 6).

Microscopically, the squamous cell carcinomas of the

oral mucosa were highly invasive, irregular masses.

Typically, they appeared to originate in the oral mucosa

of the palate adjacent to the upper molar teeth; invaded the

tongue, Harderian gland, and the soft tissues surrounding

the nose in some animals; and penetrated the maxilla

and invaded the brain in one case. Carcinomas con

sisted of a mixture of variably sized islands and short,

irregular cords of relatively well differentiated stratified

squamous epithelium, surrounded by moderate amounts

of dense fibrous connective tissue stroma (Plates 1 and

2). Frequently, the epithelium formed cyst-like struc

tures filled with keratin (keratin pearls). The squamous

cell papillomas of the oral mucosa and tongue were

exophytic masses that projected from the mucosa and

consisted of irregular papillary proliferations of mature

squamous epithelium supported by a core of fibrovascu

lar stroma. In the tongue, squamous cell carcinoma was

diagnosed when the stroma of these papillary masses

had evidence of invasion in the form of irregular foci of

dysplastic epithelium (Plates 3 and 4).

### Sodium Dichromate Dihydrate, NTP TR 546 43



### T ab le 

### 6

Incidences of Neoplasms of the Oral Cavity in Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Male

Number Necropsied 50 50 49 50 49

Oral Mucosa

Squamous Cell Papilloma a 0 0 0 0 1

Squamous Cell Carcinoma b

Overall Rate c 0/50 (0%) 0/50 (0%) 0/49 (0%) 0/50 (0%) 6/49 (12%)

Adjusted Rate d 0.0% 0.0% 0.0% 0.0% 13.6%

Terminal Rate e 0/28 (0%) 0/30 (0%) 0/30 (0%) 0/36 (0%) 1/29 (3%)

First Incidence (days)

— g

— — — 543

Poly-3 Test f P<0.001

— h

— — P=0.015

Tongue

Squamous Cell Papilloma 0 0 0 0 1

Squamous Cell Carcinoma 0 1 0 0 0

Oral Mucosa or Tongue

Squamous Cell Papilloma or Squamous Cell Carcinoma i

Overall Rate 0/50 (0%) 1/50 (2%) 0/49 (0%) 0/50 (0%) 7/49 (14%)

Adjusted Rate 0.0% 2.4% 0.0% 0.0% 15.7%

Terminal Rate 0/28 (0%) 1/30 (3%) 0/30 (0%) 0/36 (0%) 1/29 (3%)

First Incidence (days)

— 729 (T)

— — 543

Poly-3 Test P<0.001 P=0.487

— — P=0.007



### Female

Number Necropsied 50 50 50 50 50

Oral Mucosa

Squamous Cell Carcinoma j

Overall Rate 0/50 (0%) 0/50 (0%) 0/50 (0%) 2/50 (4%) 11/50 (22%)

Adjusted Rate 0.0% 0.0% 0.0% 4.6% 23.9%

Terminal Rate 0/33 (0%) 0/32 (0%) 0/32 (0%) 1/36 (3%) 2/31 (7%)

First Incidence (days)

— — — 646 506

Poly-3 Test P<0.001

— — P=0.233 P<0.001

Tongue

Squamous Cell Papilloma 1 1 0 0 0

Squamous Cell Carcinoma 0 0 0 1 0

### 44 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### 6

Incidences of Neoplasms of the Oral Cavity in Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Female (continued)

Oral Mucosa or Tongue

Squamous Cell Papilloma or Squamous Cell Carcinoma k

Overall Rate 1/50 (2%) 1/50 (2%) 0/50 (0%) 2/50 (4%) 11/50 (22%)

Adjusted Rate 2.2% 2.3% 0.0% 4.6% 23.9%

Terminal Rate 0/33 (0%) 1/32 (3%) 0/32 (0%) 1/36 (3%) 2/31 (7%)

First Incidence (days) 618 729 (T)

— 646 506

Poly-3 Test P<0.001 P=0.756 P=0.503N P=0.491 P=0.002

(T) Terminal sacrifice

a Number of animals with neoplasm

b Historical incidence for 2-year drinking water studies with controls given NTP-2000 diet (mean ± standard deviation):

0/350; all routes: 5/1,499 (0.3% ± 0.7%), range 0%-2%

c Number of animals with neoplasm per number of animals necropsied

d Poly-3 estimated neoplasm incidence after adjustment for intercurrent mortality

e Observed incidence at terminal kill

f Beneath the control incidence is the P value 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 Poly

- 3 test accounts for differential mortality in

animals that do not reach terminal sacrifice. A lower incidence in an exposed group is indicated by N

. g Not applicable; no neoplasms in animal group

h Value of statistic cannot be computed.

i Historical incidence for drinking water studies: 1/300 (0.3% ± 0.8%) , range 0%-2%; all routes: 10/1,449 (0.6% ± 0.8%), range 0%-2% j Historical incidence for drinking water studies: 0/300; all routes: 5/1,400 (0.4% ± 0.8%), range 0%-2%

k Historical incidence for drinking water studies: 3/250 (1.2% ± 1.1%), range 0%-2% ; all routes: 14/1,350 (1.1% ± 1.6%), range 0%-6%



### Liver: The incidences of minimal to moderate histiocytic

cellular infiltration in 516 mg/L males and in females

exposed to 57.3 mg/L or greater were significantly

greater than those in the controls (Tables 7, A4, and B4).

The incidences of chronic inflammation in 172 mg/L

males and all exposed groups of females were signifi

cantly increased. Chronic inflammation was generally

of minimal to mild severity in most groups, including

the controls, except 516 mg/L females in which there

appeared to be a slight increase in the severity (mild to

moderate). There were statistically significant, exposure

concentration-related increases in the incidences of fatty

change in female rats exposed to 57.3 mg/L or greater.

The incidences of basophilic focus in males exposed

to 57.3 or 172 mg/L were significantly increased. The

incidence of clear cell focus in females exposed to 172

mg/L was significantly increased.

Histiocytic infiltrates were characterized by the presence

of individual, small clusters and sometimes syncytia of histiocytes (macrophages) that were typically ran

domly scattered throughout the hepatic parenchyma but

often occurred in increased numbers within the portal

areas. The histiocytes were large (approximately 20 to

80 microns in diameter) and had abundant pale, lightly

eosinophilic, faintly stippled cytoplasm and single,

small, peripheral, dark basophilic nuclei (Plates 5 and

6). In minimally affected livers, the histiocytes often

occurred singly, whereas in more severely affected liv

ers, the histiocytes occurred as small clusters of a few

cells. The biological significance of the histiocytic

cellular infiltrates is unknown but may suggest phago

cytosis of some insoluble chemical precipitate. Chronic

inflammation consisted of small, randomly scattered

aggregates of macrophages, lymphocytes, and neu

trophils in variable numbers and in some cases were

associated with the larger histiocytic infiltrates (Plate 7).

Chronic inflammation is consistent with changes that

are considered to be background or spontaneous lesions

commonly observed in aged rats and appears to be exac

-

### Sodium Dichromate Dihydrate, NTP TR 546 45



### T ab le 

### 7

Incidences of Nonneoplastic Lesions of the Liver in Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Male

Number Examined Microscopically 50 50 49 50 49

Infiltration Cellular, Histiocyte a 1 (1.0) b 0 2 (1.0) 5 (1.4) 34** (1.4)

Inflammation, Chronic 19 (1.1) 25 (1.2) 21 (1.3) 28* (1.1) 26 (1.3)

Basophilic Focus 22 28 29* 32* 30



### Female

Number Examined Microscopically 50 50 50 50 50

Infiltration Cellular, Histiocyte 1 (1.0) 5 (1.0) 21** (1.3) 42** (2.0) 47** (2.6)

Inflammation, Chronic 12 (1.3) 21* (1.2) 28** (1.3) 35** (1.6) 39** (2.1)

Fatty Change 3 (3.3) 7 (3.6) 10* (2.5) 13** (2.5) 16** (2.8)

Clear Cell Focus 7 5 7 20** 7

* Significantly different (P # 0.05) from the control group by the Poly-3 test

** P # 0.01

a Number of animals with lesion

b Average severity grade of lesions in affected animals: 1=minimal, 2=mild, 3=moderate, 4=marked



### erbated by exposure. Fatty change consisted of scattered

hepatocytes that contained one to several variably sized,

discrete, clear, cytoplasmic vacuoles (fat droplets).

Small Intestine (Duodenum): The incidences of minimal

to mild histiocytic cellular infiltration were significantly

increased in males exposed to 57.3 mg/L or greater and

in 172 and 516 mg/L females (Tables 8, A4, and B4).

The infiltrating histiocytes were morphologically similar

to those observed in the liver and occurred singly or as

clusters of cells within the lamina propria at the tips of

the duodenal villi (Plate 8).

Mesenteric Lymph Node: The incidences of histiocytic

cellular infiltration in males exposed to 57.3 mg/L or

greater and in 172 and 516 mg/L females were sig

nificantly increased compared to the controls (Tables 8,

A4, and B4); there was a slight increase in the severity

of infiltrates in 172 and 516 mg/L females with more

animals in these groups having mild severity grades

relative to the controls and the lower exposure concen

tration groups. The incidences of minimal lymph node

hemorrhage in males exposed to 57.3 mg/L or greater and in 516 mg/L females were significantly increased

and may have been caused by the histiocytic infiltrates

in the lymph node. The histiocytic infiltrates were

morphologically similar to those that occurred in the

liver and duodenum. They formed numerous variably

sized clusters randomly scattered within the cortex and/

or medullary sinuses (Plates 9 and 10). Frequently, the

clusters coalesced to form sheets that in some cases

replaced much of the lymph node parenchyma.

Pancreatic Lymph Node: The incidences of histiocytic

cellular infiltration were increased in the 516 mg/L males

and in 57.3 mg/L or greater females with the incidence

in 172 mg/L females being significantly greater than

that in the controls (Tables 8, A4, and B4); the average

severity of infiltration in 57.3 mg/L or greater females

increased with increasing dose. Histiocytic infiltrates

were morphologically similar to those that occurred in

the liver, duodenum, and mesenteric lymph nodes.

Salivary Gland: The incidence of salivary gland atro

phy was significantly increased in 172 mg/L females

compared to that in the controls; in general, the average

### 46 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### 8

Incidences of Selected Nonneoplastic Lesions in Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Male

Small Intestine, Duodenum a 48 48 47 46 48

Infiltration Cellular, Histiocyte b 0 0 6* (1.2) c 36** (1.1) 47** (1.5)

Lymph Node, Mesenteric 49 50 49 50 49

Infiltration Cellular, Histiocyte 13 (2.0) 11 (1.5) 30** (1.9) 39** (2.1) 41** (2.1)

Hemorrhage 2 (1.5) 7 (1.1) 9* (1.3) 8* (1.1) 17** (1.3)

Lymph Node, Pancreatic 32 34 34 36 33

Infiltration Cellular, Histiocyte 17 (2.0) 22 (1.6) 17 (2.0) 17 (2.1) 25 (2.1)



### Female

Small Intestine, Duodenum 46 49 48 46 50

Infiltration Cellular, Histiocyte 0 0 1 (1.0) 30** (1.0) 47** (1.2)

Lymph Node, Mesenteric 50 50 50 50 50

Infiltration Cellular, Histiocyte 21 (1.7) 18 (1.4) 27 (1.5) 36** (2.0) 42** (2.4)

Hemorrhage 11 (1.1) 13 (1.3) 16 (1.3) 14 (1.1) 21* (1.3)

Lymph Node, Pancreatic 29 36 30 34 33

Infiltration Cellular, Histiocyte 17 (2.0) 20 (1.9) 23 (2.6) 32** (2.8) 27 (3.0)

Salivary Gland 50 50 50 50 50

Atrophy 9 (1.3) 7 (1.4) 10 (1.2) 17* (1.4) 17 (2.1)

* Significantly different (P # 0.05) from the control group by the Poly-3 test

** P # 0.01

a Number of animals with tissue 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



### severity was minimal in the controls and in the 14.3,

57.3, and 172 mg/L groups, but mild in the 516 mg/L

group. Microscopically, atrophy occurred as single,

focal lesions in the salivary glands. Minimal lesions

consisted of small, poorly defined foci of atrophic acini,

whereas mild lesions were larger, well-defined foci.

The atrophic foci consisted of shrunken glandular acini

lined by low cuboidal epithelial cells devoid of secre

tory material, accompanied by an increased prominence

of the interstitial stroma and ducts, some of which were

variably dilated (Plates 11 and 12). Atrophy is an agerelated spontaneous change commonly observed in rats.

The biological significance of the increases in female

rats in this study is uncertain. Other Findings: Exposure to sodium dichromate

dihydrate resulted in statistically significant increased

incidences of neoplasms in one or more exposed groups.

In general, the increased incidences occurred in one

sex, one or more exposed groups, and were not expo

sure concentration related. These lesions included

pancreatic acinar adenoma in males (0 mg/L, 1/50;

14.3 mg/L, 2/50; 57.3 mg/L, 6/49; 172 mg/L, 2/50;

516 mg/L, 2/49; Table A2); benign pheochromocy

toma of the adrenal medulla in males (6/49, 13/50,

14/49, 5/50, 4/49; Table A2); and mononuclear cell

leukemia in females (8/50, 18/50, 13/50, 7/50, 11/50;

Table B2). The relationship of these changes to expo

sure is uncertain.

### Sodium Dichromate Dihydrate, NTP TR 546 47



# M i c e



# 2-Y e ar 

# S t u d y



## Survival

Estimates of 2-year survival probabilities for male

and female mice are shown in Table 9 and in the

Kaplan

- Meier survival curves (Figure 3). Survival of

all exposed groups was similar to that of the control

groups.



## Body Weights, Water and Compound

Consumption, and Clinical Findings

The mean body weights of 257.4 mg/L male mice were

less than those of the controls from months 2 through 6

of the study but were only slightly less than the control

group by the end of the study; mean body weights of

172 mg/L females were less than those of the controls

from months 3 through 12 of the study; and mean body

weights of 516 mg/L females were less than those of

the controls from month 2 until the end of the study

(Tables 10 and 11; Figure 4). By the end of the study, the mean body weight of 172 mg/L females was 8% less

than that of the controls, and the mean body weight of

516 mg/L females was 15% less than that of the control

group. The lower body weights were partly attributed

to poor palatability of the dosed water and consequent

reductions in water consumption rather than direct toxic

effects of sodium dichromate dihydrate exposure. Water

consumption by 85.7 and 257.4 mg/L males and 172

and 516 mg/L females was less than that by the controls

throughout the study (Tables G3 and G4). During the

second year of the study, the average water consumption

was reduced by 15% and 35% than that of the controls

in 85.7 and 257.4 mg/L males, respectively, and by

25% and 32% than that of the controls in the 172 and

516 mg/L females, respectively. Drinking water con

centrations of 14.3, 28.6, 85.7, or 257.4 mg/L for males

and 14.3, 57.3, 172, or 516 mg/L for females resulted

in average daily doses of approximately 1.1, 2.6, 7, or

17 mg sodium dichromate dihydrate/kg body weight for

male mice and 1.1, 3.9, 9, or 25 mg/kg for female mice.

No clinical findings were attributed to sodium dichro

mate dihydrate exposure.

### 48 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### 9

Survival of Mice in the 2-Year Drinking Water Study of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 28.6 mg/L 85.7 mg/L 257.4 mg/L

Male

Animals initially in study 50 50 50 50 50

Moribund 7 5 5 4 3

Natural deaths 10 10 10 8 15

Animals surviving to study termination 33 a 35 35 38 32 a

Percent probability of survival at end of study b 66 70 70 76 64

Mean survival (days) c 700 694 682 708 689

Survival analysis d P=0.724 P=0.949N P=0.982N P=0.387N P=0.918



### 0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Female

Animals initially in study 50 50 50 50 50

Moribund 5 0 2 2 3

Natural deaths 8 11 3 6 5

Animals surviving to study termination 37 e 39 a 45 a 42 e 42

Percent probability of survival at end of study 74 78 90 84 84

Mean survival (days) 696 705 714 709 709

Survival analysis P=0.504N P=0.780N P=0.068N P=0.333N P=0.285N

a Includes one animal that died during the last week of the study

b Kaplan-Meier determinations

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 group columns. A negative trend or lower mortality in an exposed group is indicated by N

.

e Includes two animals that died during the last week of the study

### Sodium Dichromate Dihydrate, NTP TR 546 49



### F i gur e 

### 3

Kaplan-Meier Survival Curves for Male and Female Mice Exposed to Sodium Dichromate Dihydrate

in Drinking Water for 2 Years

### 50 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### 10

Mean Body Weights and Survival of Male Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

Days 0 mg/L 14.3 mg/L 28.6 mg/L

on Av. Wt. No. of Av. Wt. Wt. (% of No. of Av. Wt. Wt. (% of No. of

Study (g) Survivors (g) controls) Survivors (g) controls) Survivors

1 23.2 50 23.2 100 50 23.5 101 50

8 25.3 50 25.3 100 50 25.7 102 50

15 26.8 50 26.9 101 50 27.1 101 50

22 28.0 50 28.2 101 50 28.5 102 50

29 29.9 50 30.0 100 50 30.3 101 50

36 31.5 50 31.5 100 50 31.9 101 50

43 32.9 50 33.0 100 50 33.4 102 50

50 34.2 50 34.5 101 50 34.8 102 50

57 35.9 50 36.3 101 50 36.6 102 50

64 37.5 50 37.8 101 50 38.2 102 49

71 38.9 50 39.4 101 50 39.9 103 49

78 40.3 50 40.6 101 50 41.2 102 49

85 41.7 50 41.8 100 50 42.4 102 49

113 46.7 50 46.5 100 50 47.2 101 49

141 48.9 50 48.7 100 50 49.2 101 49

169 50.1 50 49.9 100 50 50.2 100 49

197 51.4 50 51.8 101 50 51.8 101 49

225 52.2 50 52.6 101 50 52.5 101 49

253 52.7 50 52.7 100 50 52.7 100 49

281 53.8 50 53.8 100 50 53.7 100 49

309 53.8 50 53.6 100 50 53.9 100 49

337 54.5 50 54.6 100 50 54.7 100 49

365 55.2 50 55.0 100 49 55.0 100 49

393 55.5 50 55.2 100 49 55.2 100 49

421 55.1 50 54.9 100 49 54.1 98 49

449 55.3 49 55.0 100 49 54.4 98 49

477 55.6 49 55.2 99 49 54.2 98 49

505 55.1 48 53.7 97 49 53.6 97 47

533 54.0 48 52.6 97 48 52.9 98 47

561 54.3 48 52.5 97 48 53.1 98 45

589 53.0 48 52.1 98 45 52.3 99 43

617 52.0 48 51.6 99 44 50.7 98 42

645 51.7 44 50.7 98 41 49.3 96 39

673 51.7 38 50.5 98 37 48.8 94 38

701 50.3 36 49.9 99 35 46.9 93 37



### Mean for weeks

1-13 32.8 33.0 101 33.3 102

14-52 51.6 51.6 100 51.8 100

53-101 53.8 53.0 99 52.3 97

### Sodium Dichromate Dihydrate, NTP TR 546 51



### T ab le 

### 10

Mean Body Weights and Survival of Male Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

Days 85.7 mg/L 257.4 mg/L

on Av. Wt. Wt. (% of No. of Av. Wt. Wt. (% of No. of

Study (g) controls) Survivors (g) controls) Survivors

1 23.2 100 50 23.2 100 50

8 25.2 100 50 24.4 97 50

15 26.6 99 50 25.4 95 50

22 27.8 99 50 26.3 94 50

29 29.5 99 50 27.5 92 50

36 31.0 98 50 28.6 91 50

43 32.1 98 50 29.5 90 50

50 33.6 98 50 30.4 89 50

57 35.0 98 50 31.4 88 50

64 36.5 97 50 32.2 86 50

71 37.9 98 50 33.3 86 50

78 39.1 97 50 34.4 85 50

85 40.4 97 50 35.2 84 50

113 45.1 97 50 38.9 83 50

141 47.9 98 50 42.2 86 50

169 49.5 99 50 44.5 89 50

197 51.6 100 50 47.4 92 50

225 51.8 99 50 48.3 93 50

253 52.4 99 50 48.9 93 50

281 53.3 99 50 49.7 92 50

309 53.5 99 50 49.9 93 50

337 54.4 100 50 50.4 93 50

365 54.4 99 50 50.8 92 50

393 55.0 99 50 50.9 92 49

421 54.6 99 50 50.8 92 48

449 55.1 100 50 50.8 92 48

477 55.1 99 50 50.9 92 46

505 54.4 99 50 50.3 91 46

533 53.8 100 50 49.9 92 46

561 52.8 97 49 49.8 92 46

589 52.1 98 47 48.8 92 46

617 51.3 99 46 49.3 95 44

645 49.6 96 44 49.3 95 41

673 48.6 94 42 48.1 93 40

701 48.4 96 39 47.2 94 37



### Mean for weeks

1-13 32.1 98 29.4 90

14-52 51.1 99 46.7 91

53-101 52.7 98 49.8 93

### 52 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### 11

Mean Body Weights and Survival of Female Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

Days 0 mg/L 14.3 mg/L 57.3 mg/L

on Av. Wt. No. of Av. Wt. Wt. (% of No. of Av. Wt. Wt. (% of No. of

Study (g) Survivors (g) controls) Survivors (g) controls) Survivors

1 17.8 50 17.5 99 50 17.4 98 50

9 19.2 50 19.2 100 50 19.0 99 50

16 20.6 50 20.6 100 50 20.3 98 50

23 21.3 50 21.4 100 50 21.0 99 50

30 22.5 50 22.3 99 50 21.8 97 50

37 23.2 50 23.2 100 50 22.7 98 50

44 24.4 50 24.4 100 50 23.8 98 50

51 26.0 50 25.4 98 50 24.8 96 50

58 26.9 50 26.4 98 50 25.4 95 50

65 27.9 50 27.4 98 50 26.2 94 50

72 28.9 50 28.3 98 50 27.1 94 50

79 30.3 50 29.7 98 50 28.6 94 50

86 31.2 50 31.0 99 50 29.7 95 50

114 37.0 50 36.9 100 50 34.4 93 50

142 41.5 50 41.3 100 50 38.5 93 50

170 44.8 50 44.9 100 50 41.9 93 50

198 48.7 50 48.2 99 50 46.5 96 50

226 51.6 49 51.7 100 50 48.8 95 50

254 53.3 49 53.6 101 50 50.6 95 50

282 55.2 49 55.6 101 50 52.5 95 50

310 59.0 49 57.9 98 50 55.1 93 50

338 59.8 49 59.0 99 50 56.7 95 49

366 62.1 49 62.1 100 50 60.0 97 49

394 61.5 49 60.9 99 50 59.0 96 49

422 62.2 49 62.5 100 50 60.1 97 49

450 63.1 49 62.8 100 50 61.6 98 49

478 64.3 49 64.8 101 49 62.7 97 49

506 63.9 49 65.0 102 48 62.4 98 49

534 62.7 49 64.0 102 48 61.6 98 49

562 61.8 48 62.9 102 48 60.8 99 49

590 61.3 47 62.7 102 46 59.8 98 49

618 60.3 45 62.1 103 46 59.7 99 47

646 60.6 42 61.1 101 44 58.6 97 46

674 59.8 39 60.2 101 43 58.1 97 46

702 60.6 37 60.7 100 40 58.1 96 46



### Mean for weeks

1-13 24.6 24.4 99 23.7 96

14-52 50.1 49.9 100 47.2 94

53-101 61.9 62.4 101 60.2 97

### Sodium Dichromate Dihydrate, NTP TR 546 53



### T ab le 

### 11

Mean Body Weights and Survival of Female Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

Days 172 mg/L 516 mg/L

on Av. Wt. Wt. (% of No. of Av. Wt. Wt. (% of No. of

Study (g) controls) Survivors (g) controls) Survivors

1 17.7 100 50 17.5 99 50

9 19.1 100 50 18.4 96 50

16 20.2 98 50 19.3 93 50

23 20.8 98 50 19.9 94 50

30 21.5 96 50 20.8 93 50

37 22.4 97 50 21.3 92 50

44 23.1 95 50 22.3 92 50

51 23.9 92 50 23.3 99 50

58 24.6 92 50 23.8 89 50

65 25.2 90 50 24.6 88 50

72 25.9 89 50 24.7 86 50

79 26.8 88 50 25.5 84 50

86 27.5 88 50 26.2 84 50

114 31.4 85 50 28.6 77 50

142 35.1 85 50 30.8 74 50

170 37.6 84 50 32.8 73 49

198 41.5 85 50 36.0 74 49

226 43.7 85 50 37.5 73 49

254 45.5 85 50 38.9 73 49

282 47.8 87 50 41.0 74 49

310 50.4 85 50 43.9 74 49

338 52.7 88 50 45.4 76 49

366 55.4 89 50 48.1 78 49

394 55.8 91 50 48.4 79 49

422 57.1 92 50 49.2 79 49

450 57.7 91 49 50.0 79 49

478 59.1 92 49 51.9 81 49

506 58.4 91 49 51.9 81 49

534 57.7 92 49 51.9 83 49

562 57.6 93 47 51.8 84 49

590 57.1 93 47 51.2 84 49

618 57.5 95 45 51.6 86 49

646 56.5 93 44 50.7 84 47

674 56.1 94 44 50.8 85 45

702 55.8 92 44 51.4 85 42



### Mean for weeks

1-13 23.0 93 22.1 90

14-52 42.9 86 37.2 74

53-101 57.1 92 50.7 82

### 54 Sodium Dichromate Dihydrate, NTP TR 546



### F i gur e 

### 4

Growth Curves for Male and Female Mice Exposed

to Sodium Dichromate Dihydrate in Drinking Water for 2 Years

### Sodium Dichromate Dihydrate, NTP TR 546 55



## Hematology

The hematology data for female mice in the 2-year study

of sodium dichromate dihydrate are listed in Tables 12

and E2. Similar to the rat study, an exposure-related

microcytosis, evidenced by decreased mean cell volume

values, occurred in mice. The female mice were less

affected than the male rats. A minimal (less than or

equal to 8%) decrease in mean cell volume occurred at all time points; the 172 and 516 mg/L groups were con

sistently affected. Changes in mean cell hemoglobin

values mimicked the alterations in mean cell volume and

reflected the smaller erythrocytes. Erythrocyte counts

demonstrated small (less than or equal to 14%) increases

at all time points with the 516 mg/L group most con

sistently affected. However, no other estimators of the

erythron demonstrated any effects.

### 56 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### 12

Selected Hematology Data for Female Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate a



### 0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

n

Day 22 10 10 10 10 10

Month 3 10 10 10 10 10

Month 6 10 10 10 10 10

Month 12 10 10 9 10 10

Hematocrit (auto) (%)

Day 22 50.0 ± 0.7 49.2 ± 0.4 50.0 ± 0.9 50.6 ± 0.7 49.6 ± 0.5

Month 3 47.7 ± 0.7 49.9 ± 0.5* 49.2 ± 0.8 49.4 ± 0.6 50.4 ± 0.5*

Month 6 48.4 ± 0.7 49.2 ± 0.5 47.8 ± 0.6 48.0 ± 0.8 49.2 ± 0.8

Month 12 45.0 ± 0.5 45.6 ± 0.3 45.2 ± 0.6 45.0 ± 0.7 45.1 ± 0.8

Hematocrit (spun) (%)

Day 22 50.0 ± 0.7 49.0 ± 0.3 49.4 ± 0.8 49.6 ± 0.7 48.5 ± 0.5

Month 3 48.3 ± 0.6 50.4 ± 0.5* 49.3 ± 0.6 49.4 ± 0.5 50.4 ± 0.4*

Month 6 49.0 ± 0.6 50.2 ± 0.5 48.7 ± 0.5 48.9 ± 0.8 49.9 ± 0.7

Month 12 46.5 ± 0.4 47.4 ± 0.2 46.9 ± 0.5 46.4 ± 0.6 46.7 ± 0.6

Hemoglobin (g/dL)

Day 22 16.8 ± 0.2 16.5 ± 0.1 16.7 ± 0.3 16.9 ± 0.2 16.4 ± 0.2

Month 3 16.0 ± 0.2 16.7 ± 0.2* 16.4 ± 0.3 16.3 ± 0.2 16.5 ± 0.2

Month 6 16.1 ± 0.2 16.4 ± 0.2 16.0 ± 0.2 16.0 ± 0.3 16.2 ± 0.3

Month 12 14.9 ± 0.1 15.3 ± 0.2 15.1 ± 0.2 15.0 ± 0.2 14.9 ± 0.3

Erythrocytes (10 6 / μ L)

Day 22 10.25 ± 0.15 10.20 ± 0.08 10.47 ± 0.19 10.77 ± 0.13* 10.61 ± 0.13*

Month 3 10.10 ± 0.16 10.66 ± 0.13* 10.55 ± 0.17* 10.95 ± 0.10** 11.55 ± 0.16**

Month 6 10.56 ± 0.15 10.81 ± 0.10 10.60 ± 0.13 10.77 ± 0.20 11.50 ± 0.20**

Month 12 9.58 ± 0.10 9.72 ± 0.09 9.77 ± 0.10 9.95 ± 0.13* 10.30 ± 0.21**

Reticulocytes (10 6 / μ L)

Day 22 0.32 ± 0.01 0.30 ± 0.01 0.33 ± 0.02 0.31 ± 0.01 0.32 ± 0.02

Month 3 0.33 ± 0.01 0.31 ± 0.01 0.34 ± 0.02 0.34 ± 0.03 0.34 ± 0.02

Month 6 0.36 ± 0.02 0.37 ± 0.01 0.39 ± 0.04 0.36 ± 0.03 0.35 ± 0.02

Month 12 0.32 ± 0.02 0.33 ± 0.01 0.32 ± 0.01 0.36 ± 0.02 0.37 ± 0.02

Nucleated erythrocytes (10 3 / μ L)

Day 22 0.00 ± 0.00 0.00 ± 0.00 0.00 ± 0.00 0.00 ± 0.00 0.00 ± 0.00

Month 3 0.00 ± 0.00 0.10 ± 0.10 0.00 ± 0.00 0.00 ± 0.00 0.00 ± 0.00

Month 6 0.10 ± 0.10 0.10 ± 0.10 0.00 ± 0.00 0.00 ± 0.00 0.00 ± 0.00

Month 12 0.00 ± 0.00 b 0.00 ± 0.00 0.00 ± 0.00 0.00 ± 0.00 0.00 ± 0.00

Mean cell volume (fL)

Day 22 48.8 ± 0.2 48.3 ± 0.1* 47.8 ± 0.2** 47.0 ± 0.2** 46.8 ± 0.2**

Month 3 47.2 ± 0.1 46.9 ± 0.3 46.7 ± 0.1 45.1 ± 0.2** 43.7 ± 0.3**

Month 6 45.8 ± 0.2 45.5 ± 0.3 45.1 ± 0.2* 44.6 ± 0.2** 42.8 ± 0.3**

Month 12 46.9 ± 0.3 46.9 ± 0.3 46.3 ± 0.3 45.2 ± 0.2** 43.9 ± 0.5**

Mean cell hemoglobin (pg)

Day 22 16.4 ± 0.1 16.2 ± 0.0* 15.9 ± 0.1** 15.7 ± 0.1** 15.5 ± 0.1**

Month 3 15.8 ± 0.0 15.7 ± 0.1 15.6 ± 0.0** 14.9 ± 0.1** 14.3 ± 0.1**

Month 6 15.3 ± 0.1 15.2 ± 0.1 15.1 ± 0.1 14.9 ± 0.1** 14.1 ± 0.1**

Month 12 15.5 ± 0.1 15.7 ± 0.2 15.5 ± 0.1 15.1 ± 0.1* 14.4 ± 0.2**

Mean cell hemoglobin concentration (g/dL)

Day 22 33.6 ± 0.1 33.5 ± 0.1 33.3 ± 0.2 33.4 ± 0.1 33.1 ± 0.1**

Month 3 33.5 ± 0.1 33.5 ± 0.1 33.3 ± 0.1 33.1 ± 0.1** 32.8 ± 0.1**

Month 6 33.4 ± 0.2 33.4 ± 0.1 33.5 ± 0.2 33.4 ± 0.1 32.9 ± 0.1

Month 12 33.1 ± 0.2 33.5 ± 0.2 33.4 ± 0.1 33.3 ± 0.1 32.9 ± 0.1

* Significantly different (P # 0.05) from the control group by Dunn’s or Shirley’s test

** P # 0.01

a Mean ± standard error. Statistical tests were performed on unrounded data.

b n=9

### Sodium Dichromate Dihydrate, NTP TR 546 57



## Pathology and Statistical Analyses

This section describes the statistically significant or

biologically noteworthy changes in the incidences of

neoplasms and/or nonneoplastic lesions of the small

intestine (duodenum, jejunum, ileum), liver, mesenteric

lymph node, pancreatic lymph node, and pancreas.

Summaries of the incidences of neoplasms and non

neoplastic lesions, statistical analyses of primary neo

plasms 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.

Small Intestine (Duodenum, Jejunum, and Ileum): In the

duodenum, the incidences of adenoma occurred with a

positive trend in males and females. The incidences of

adenoma in 257.4 mg/L males and 172 and 516 mg/L

females were significantly greater that those in the

controls (Tables 13, C2, and D2). The incidences of

multiple adenoma were also significantly increased in

257.4 mg/L males and in 516 mg/L females. Adenomas

were observed in one control, one 28.6 mg/L, and five

85.7 mg/L males and in two 57.3 mg/L females; none of

these increased incidences were statistically significant.

However, the incidences of adenoma in 85.7 mg/L males

and 57.3 mg/L females exceeded the historical control

ranges for drinking water studies and for all routes of

administration (Tables 13, C3, and D3). The incidences

of carcinoma of the duodenum were increased in 85.7

and 257.4 mg/L males and in 172 and 516 mg/L females;

the incidence in 516 mg/L females was significantly

greater than that in the controls. The incidences of

carcinoma in 257.4 mg/L males and 516 mg/L females

exceeded the historical control ranges for drinking water

studies and for all routes of administration.

In the jejunum, the incidence of adenoma in 516 mg/L

females was significantly increased compared to that

in the controls (Tables 13 and D2). In females, one

adenoma occurred in the 14.3 mg/L group and two

adenomas occurred in the 172 mg/L group; the inci

dence in 172 mg/L females exceeded the historical

control ranges for drinking water studies and for all

routes of administration (Tables 13, C3, and D3). The

incidence of adenoma was greater in 257.4 mg/L males

but was not significantly increased compared to the

controls. However, the incidence exceeded the histori

cal control ranges for drinking water studies and for all

routes of administration (Tables 13 and C3). In the his

torical controls for the jejunum, adenoma has not been observed in mice in drinking water studies, and only

one adenoma has been observed in males for all routes

of administration. Low incidences of carcinoma of the

jejunum occurred in exposed male and female mice; in

males, the incidences of carcinoma in the 14.3, 85.7, and

257.4 mg/L groups did not exceed the historical control

ranges for drinking water studies or for all routes of

administration (Tables 13, C2, and C3). In females, the

incidences of carcinoma of the jejunum in the 57.3 and

172 mg/L groups exceeded the historical control ranges

for drinking water studies and for all routes of adminis

tration (Tables 13, D2, and D3).

For the entire small intestine (duodenum, jejunum, and

ileum), the incidences of adenoma and carcinoma in

257.4 mg/L males and the incidences of adenoma or

carcinoma (combined) in 85.7 and 257.4 mg/L males

were significantly greater than those in the controls. The

incidences of adenoma in 85.7 mg/L males exceeded the

historical control ranges for drinking water studies and

for all routes of administration (Tables 13, C2, and C3).

For the entire small intestine, the incidence of adenoma

in 172 mg/L females, the incidences of adenoma and

carcinoma in 516 mg/L females, and the incidences of

adenoma or carcinoma (combined) in 172 and 516 mg/L

females were significantly increased. The incidences of

adenoma, carcinoma, and adenoma or carcinoma (com

bined) in 57.3 mg/L females exceeded the historical con

trol ranges for drinking water studies and for all routes of

administration (Tables 13, D2, and D3). The incidences

of carcinoma in 172 mg/L females exceeded the histori

cal control ranges for drinking water studies and for all

routes of administration (Tables 13 and D3).

Adenomas were discrete, broad based, focally exten

sive, plaque-like lesions that thickened the mucosa

and protruded into the lumen (Plates 13 and 14). They

were composed of irregular, elongated, often branching

crypts and irregular, glandular structures lined by one to

several layers of densely packed, atypical, cuboidal to

tall columnar, hyperchromatic epithelial cells with large

oval to elongated nuclei. Increased mitotic activity was

commonly evident.

Carcinomas were extensive, sessile, plaque-like neo

plasms distinguished from adenomas by dysplastic epi

thelial growth, complete effacement of the mucosa with

invasion of the submucosa and/or muscularis mucosa,

degree of cellular atypia, and the presence of variable

fibroplasia/desmoplasia (Plates 15 and 16). They were

composed of hyperchromatic, atypical, pleomorphic

### 58 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### 13

Incidences of Neoplasms and Nonneoplastic Lesions in the Small Intestine of Mice

in the 2-Year Drinking Water Study of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 28.6 mg/L 85.7 mg/L 257.4 mg/L

Male

Number Necropsied 50 50 50 50 50

Duodenum

Epithelium, Hyperplasia, Focal a 0 0 0 1 (3.0) b 2 (3.5)

Epithelium, Hyperplasia, Diffuse 0 11** (2.0) 18** (1.6) 42** (2.1) 32** (2.1)

Infiltration Cellular, Histiocyte 0 2 (1.0) 4 (1.0) 37** (1.2) 35** (1.7)

Adenoma, Multiple 0 0 0 0 6*

Adenoma (includes multiple) c

Overall Rate d 1/50 (2%) 0/50 (0%) 1/50 (2%) 5/50 (10%) 15/50 (30%)

Adjusted Rate e 2.2% 0.0% 2.3% 10.8% 32.9%

Terminal Rate f 0/33 (0%) 0/35 (0%) 1/35 (3%) 5/38 (13%) 10/32 (31%)

First Incidence (days) 665

— h 729 (T) 729 (T) 451

Poly-3 Test g P<0.001 P=0.505N P=0.751 P=0.106 P<0.001

Carcinoma i

Overall Rate 0/50 (0%) 0/50 (0%) 0/50 (0%) 2/50 (4%) 3/50 (6%)

Adjusted Rate 0.0% 0.0% 0.0% 4.3% 6.8%

Terminal Rate 0/33 (0%) 0/35 (0%) 0/35 (0%) 2/38 (5%) 3/32 (9%)

First Incidence (days)

— — — 729 (T) 729 (T)

Poly-3 Test P=0.011

— j

— P=0.243 P=0.113

Jejunum

Adenoma k

Overall Rate 0/50 (0%) 0/50 (0%) 0/50 (0%) 0/50 (0%) 3/50 (6%)

Adjusted Rate 0.0% 0.0% 0.0% 0.0% 6.8%

Terminal Rate 0/33 (0%) 0/35 (0%) 0/35 (0%) 0/38 (0%) 2/32 (6%)

First Incidence (days)

— — — — 714

Poly-3 Test P=0.002

— — — P=0.114

Carcinoma, Multiple 0 1 0 0 0

Carcinoma (includes multiple) l 0 2 0 1 2

Duodenum, Jejunum, or Ileum

Adenoma m

Overall Rate 1/50 (2%) 1/50 (2%) 1/50 (2%) 5/50 (10%) 17/50 (34%)

Adjusted Rate 2.2% 2.3% 2.3% 10.8% 37.2%

Terminal Rate 0/33 (0%) 1/35 (3%) 1/35 (3%) 5/38 (13%) 11/32 (34%)

First Incidence (days) 665 729 (T) 729 (T) 729 (T) 451

Poly-3 Test P<0.001 P=0.755 P=0.751 P=0.106 P<0.001

Carcinoma n

Overall Rate 0/50 (0%) 2/50 (4%) 1/50 (2%) 3/50 (6%) 5/50 (10%)

Adjusted Rate 0.0% 4.5% 2.3% 6.5% 11.4%

Terminal Rate 0/33 (0%) 2/35 (6%) 1/35 (3%) 3/38 (8%) 5/32 (16%)

First Incidence (days)

— 729 (T) 729 (T) 729 (T) 729 (T)

Poly-3 Test P=0.014 P=0.233 P=0.492 P=0.123 P=0.028

Adenoma or Carcinoma o

Overall Rate 1/50 (2%) 3/50 (6%) 2/50 (4%) 7/50 (14%) 20/50 (40%)

Adjusted Rate 2.2% 6.8% 4.6% 15.1% 43.8%

Terminal Rate 0/33 (0%) 3/35 (9%) 2/35 (6%) 7/38 (18%) 14/32 (44%)

First Incidence (days) 665 729 (T) 729 (T) 729 (T) 451

Poly-3 Test P<0.001 P=0.296 P=0.485 P=0.032 P<0.001

### Sodium Dichromate Dihydrate, NTP TR 546 59



### T ab le 

### 13

Incidences of Neoplastic and Nonneoplastic Lesions in the Small Intestine of Mice

in the 2-Year Drinking Water Study of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Female

Number Necropsied 50 50 50 50 50

Duodenum

Epithelium, Hyperplasia, Focal 0 0 1 (2.0) 2 (3.0) 0

Epithelium, Hyperplasia, Diffuse 0 16** (1.6) 35** (1.7) 31** (1.6) 42** (2.2)

Infiltration Cellular, Histiocyte 0 0 4 (1.3) 33** (1.2) 40** (2.0)

Adenoma, Multiple 0 0 0 1 6*

Adenoma (includes multiple) p

Overall Rate 0/50 (0%) 0/50 (0%) 2/50 (4%) 13/50 (26%) 12/50 (24%)

Adjusted Rate 0.0% 0.0% 4.2% 27.8% 25.2%

Terminal Rate 0/37 (0%) 0/39 (0%) 2/45 (4%) 13/42 (31%) 11/42 (26%)

First Incidence (days)

— — 729 (T) 729 (T) 693

Poly-3 Test P<0.001

— P=0.251 P<0.001 P<0.001

Carcinoma q

Overall Rate 0/50 (0%) 0/50 (0%) 0/50 (0%) 1/50 (2%) 6/50 (12%)

Adjusted Rate 0.0% 0.0% 0.0% 2.1% 12.6%

Terminal Rate 0/37 (0%) 0/39 (0%) 0/45 (0%) 1/42 (2%) 5/42 (12%)

First Incidence (days)

— — — 729 (T) 625

Poly-3 Test P<0.001

— — P=0.507 P=0.019

Jejunum

Epithelium, Hyperplasia, Diffuse 0 2 (2.0) 1 (2.0) 0 8** (1.9)

Infiltration Cellular, Histiocyte 0 0 0 2 (1.0) 8** (1.6)

Adenoma, Multiple 0 0 0 0 1

Adenoma (includes multiple) r

Overall Rate 0/50 (0%) 1/50 (2%) 0/50 (0%) 2/50 (4%) 5/50 (10%)

Adjusted Rate 0.0% 2.2% 0.0% 4.3% 10.6%

Terminal Rate 0/37 (0%) 1/39 (3%) 0/45 (0%) 2/42 (5%) 5/42 (12%)

First Incidence (days)

— 729 (T)

— 729 (T) 729 (T)

Poly-3 Test P=0.002 P=0.504

— P=0.246 P=0.035

Carcinoma s 1 0 2 2 1

Duodenum, Jejunum, or Ileum

Adenoma t

Overall Rate 0/50 (0%) 1/50 (2%) 2/50 (4%) 15/50 (30%) 16/50 (32%)

Adjusted Rate 0.0% 2.2% 4.2% 32.0% 33.7%

Terminal Rate 0/37 (0%) 1/39 (3%) 2/45 (4%) 15/42 (36%) 15/42 (36%)

First Incidence (days)

— 729 (T) 729 (T) 729 (T) 693

Poly-3 Test P<0.001 P=0.504 P=0.251 P<0.001 P<0.001

Carcinoma u

Overall Rate 1/50 (2%) 0/50 (0%) 2/50 (4%) 3/50 (6%) 7/50 (14%)

Adjusted Rate 2.2% 0.0% 4.2% 6.4% 14.7%

Terminal Rate 1 /37 (3%) 0/39 (0%) 2/45 (4%) 3/42 (7%) 6/42 (14%)

First Incidence (days) 729 (T)

— 729 (T) 729 (T) 625

Poly-3 Test P<0.001 P=0.496N P=0.521 P=0.319 P=0.037

### 60 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### 13

Incidences of Neoplastic and Nonneoplastic Lesions in the Small Intestine of Mice

in the 2-Year Drinking Water Study of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Female (continued)

Adenoma or Carcinoma v

Overall Rate 1/50 (2%) 1/50 (2%) 4/50 (8%) 17/50 (34%) 22/50 (44%)

Adjusted Rate 2.2% 2.2% 8.3% 36.3% 45.9%

Terminal Rate 1 /37 (3%) 1/39 (3%) 4/45 (9%) 17/42 (41%) 20/42 (48%)

First Incidence (days) 729 (T) 729 (T) 729 (T) 729 (T) 625

Poly-3 Test P<0.001 P=0.756N P=0.198 P<0.001 P<0.001

(T) Terminal sacrifice

* Significantly different (P # 0.05) from the control group by the Poly-3 test

** P # 0.01

a Number of animals with lesion

b Average severity grade of lesions in affected animals: 1=minimal, 2=mild, 3=moderate, 4=marked

c Historical incidence for 2-year drinking water studies with controls given NTP-2000 diet (mean ± standard deviation):

6/299 (2.0% ± 2.2%), range 0%-6% ; all routes: 9/1,549 (0.6% ± 1.3%), range 0%-6%

d Number of animals with neoplasm per number of animals necropsied

e Poly-3 estimated neoplasm incidence after adjustment for intercurrent mortality

f Observed incidence at terminal kill

g Beneath the control incidence is the P value 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 Poly

- 3 test accounts for differential mortality in

animals that do not reach terminal sacrifice. A lower incidence in an exposed group is indicated by N

h Not applicable; no neoplasms in animal group

i Historical incidence for drinking water studies: 1/299 (0.3% ± 0.8%), range 0%-2% ; all routes: 3/1,549 (0.2% ± 0.8%), range 0%-4% j Value of statistic cannot be computed.

k Historical incidence for drinking water studies: 0/299; all routes: 1/1,549 (0.1% ± 0.4%), range 0%-2%

l Historical incidence for drinking water studies: 5/299 (1.7% ± 1.5%), range 0%-4% ; all routes: 25/1,549 (1.6% ± 2.2%), range 0%-8%

m Historical incidence for drinking water studies: 6/299 (2.0% ± 2.2%), range 0%-6% ; all routes: 10/1,549 (0.7% ± 1.3%), range 0%-6%

n Historical incidence for drinking water studies: 6/299 (2.0% ± 1.8%), range 0%-4% ; all routes: 30/1,549 (2.0% ± 2.2%), range 0%-8%

o Historical incidence for drinking water studies: 11/299 (3.7% ± 3.7%), range 0%-10% ; all routes: 39/1,549 (2.6% ± 2.7%),

range 0%-10%

p Historical incidence for drinking water studies: 1/350 (0.3% ± 0.8%), range 0%-2% ; all routes: 3/1,648 (0.2% ± 0.6%), range 0%-2%

q Historical incidence for drinking water studies: 0/350; all routes: 1/1,648 (0.1% ± 0.4%), range 0%-2%

r Historical incidence for drinking water studies: 0/350; all routes: 0/1,648

s Historical incidence for drinking water studies: 2/350 (0.6% ± 1.0%), range 0%-2% ; all routes: 5/1,648 (0.3% ± 0.7%), range 0%-2%

t Historical incidence for drinking water studies: 1/350 (0.3% ± 0.8%), range 0%-2% ; all routes: 3/1,648 (0.2% ± 0.6%), range 0%-2%

u Historical incidence for drinking water studies: 3/350 (0.9% ± 1.1%), range 0%-2% ; all routes: 8/1,648 (0.5% ± 0.8%), range 0%-2%

v Historical incidence for drinking water studies: 4/350 (1.1% ± 1.6%), range 0%-4% ; all routes: 11/1,648 (0.7% ± 1.1%), range 0%-4%

### Sodium Dichromate Dihydrate, NTP TR 546 61



### (cuboidal, round, polygonal, columnar) epithelial cells

that had round, oval, or elongated hyperchromatic nuclei.

Increased mitotic activity was evident to a greater extent

than in adenomas, and many mitoses were atypical.

Low incidences of focal epithelial hyperplasia occurred

in the duodenum of exposed male and female mice

(Tables 13, C4, and D4). Although the increased

incidences were not exposure concentration-related or

statistically significant, this lesion was considered a

preneoplastic lesion related to exposure to sodium

dichromate dihydrate because of its morphologic simi

larities to adenoma. Focal epithelial hyperplasias were

distinguished from adenomas in that they were smaller,

commonly located in the superficial mucosa, and were

less discrete with margins that tended to blend with the

normal surrounding mucosal epithelium. These hyper

plastic lesions occurred as focal disorganized areas of

increased cellularity that stained more basophilic than

the surrounding histologically normal mucosa (Plates

17 and 18). They were composed of crypts and villi

that were lined by increased numbers of cuboidal to

tall columnar epithelial cells that were morphologically

similar to those of the adenomas.

The incidences of diffuse epithelial hyperplasia were

significantly increased in the duodenum of all exposed

groups of male and female mice (Tables 13, C4, and D4).

In the jejunum, the incidence of diffuse epithelial hyper

plasia was significantly increased in 516 mg/L females.

Diffuse epithelial hyperplasia generally involved the

entire mucosa. Compared to the controls, the duodenal

villi of exposed mice were short, broad, blunt, and lined

by densely packed, tall columnar epithelial cells that

were more basophilic than the shorter epithelial cells

lining the duodenum villi of the controls (Plates 19 to

22). The epithelial cells and cell nuclei were often piled

up in multiple layers along the long axis of the villi.

Intestinal crypts were often elongated and generally

appeared to contain increased numbers of epithelial cells

with increased numbers of mitotic figures. Collectively,

these lesions are considered consistent with regenerative

hyperplasia secondary to previous epithelial cell injury.

The incidences of histiocytic cellular infiltration were

significantly increased in the duodenum of 85.7 and

257.4 mg/L males and of 172 and 516 mg/L females

(Tables 13, C4, and D4). In the jejunum, the inci

dence of histiocytic cellular infiltration was significantly

increased in 516 mg/L females compared to the controls.

Histiocyte infiltrates in the duodenum and jejunum were consistent with those observed in the duodenum of rats.

Infiltrates ranged from small clusters of three to five

cells in the lower exposure groups to larger clusters

that expanded the tips of the affected villi in the higher

exposure groups.

Liver: The incidences of hepatoblastoma in 14.3, 85.7,

and 257.4 mg/L males were significantly less than that

in the controls (0 mg/L, 17/50; 14.3 mg/L, 8/50; 28.6

mg/L, 11/50; 85.7 mg/L, 2/50; 257.4 mg/L, 0/50; Table

C2). The incidences of hepatocellular adenoma or car

cinoma (combined) in 28.6 mg/L males (42/50, 42/50,

33/50, 37/50, 41/50) and hepatocellular adenoma, hepa

tocellular carcinoma, or hepatoblastoma (combined) in

28.6 and 85.7 mg/L males (46/50, 42/50, 37/50, 37/50,

41/50) were significantly decreased. The incidences of

hepatocellular adenoma in 172 and 516 mg/L females

were significantly less than that in the controls (0 mg/L,

14/49; 14.3 mg/L, 21/50; 57.3 mg/L, 13/50; 172 mg/L,

6/50; 516 mg/L, 3/50; Table D2). The biological signifi

cance of these decreases is unknown.

The incidences of histiocytic cellular infiltration were

significantly increased in all exposed groups of females

(Tables 14 and D4). The incidence of chronic inflam

mation was significantly increased in 172 mg/L females.

The incidences of histiocytic cellular infiltration and

chronic inflammation in female mice were consistent

with those observed in rats. The incidence of clear cell

focus in 257.4 mg/L males was significantly less than

that in the controls (Tables 14 and C4). The incidences

of eosinophilic focus in 257.4 mg/L males and 172 and

516 mg/L females were significantly less than those in

the controls.

Mesenteric Lymph Node: The incidences of minimal to

moderate histiocytic cellular infiltration in all exposed

groups of male and female mice were significantly

greater than those in the controls (Tables 14, C4, and

D4). In general, there was a slight increase in the sever

ity with increasing exposure concentration. Histiocytic

cellular infiltration in mice was consistent with that

observed in rats.

Pancreatic Lymph Node: The incidences of minimal

to moderate histiocytic cellular infiltration in 85.7 and

257.4 mg/L males and in 172 and 516 mg/L females

were significantly greater than those in the controls

(Tables 14, C4, and D4). Histiocytic cellular infiltration

in mice was consistent with that observed in rats.

### 62 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### 14

Incidences of Selected Nonneoplastic Lesions in Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 28.6 mg/L 85.7 mg/L 257.4 mg/L

Male

Liver a 50 50 50 50 50

Clear Cell Focus b 20 17 19 16 7**

Eosinophilic Focus 27 26 19 21 12**

Lymph Node, Mesenteric 47 47 49 49 46

Infiltration Cellular, Histiocyte 14 (1.2) c 38** (1.1) 31** (1.2) 32** (1.5) 42** (2.5)

Lymph Node, Pancreatic 5 13 10 8 16

Infiltration Cellular, Histiocyte 0 2 (1.0) 2 (1.0) 5* (1.4) 12** (2.3)

Pancreas 49 49 50 49 48

Acinus, Cytoplasmic Alteration 0 1 (3.0) 1 (3.0) 9** (2.1) 8** (2.6)



### 0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Female

Liver 49 50 50 50 50

Infiltration Cellular, Histiocyte 2 (1.0) 15** (1.1) 23** (1.0) 32** (1.0) 45** (1.9)

Inflammation, Chronic 16 (1.1) 21 (1.1) 22 (1.1) 27* (1.1) 24 (1.0)

Eosinophilic Focus 14 18 8 5* 4**

Lymph Node, Mesenteric 46 48 46 50 50

Infiltration Cellular, Histiocyte 3 (1.0) 29** (1.3) 26** (1.1) 40** (1.9) 42** (2.7)

Lymph Node, Pancreatic 14 12 15 14 13

Infiltration Cellular, Histiocyte 0 1 (1.0) 2 (1.5) 7** (1.9) 8** (2.5)

Pancreas 48 50 49 50 50

Acinus, Cytoplasmic Alteration 0 6* (2.5) 6* (2.0) 14** (2.4) 32** (2.6)

* Significantly different (P # 0.05) from the control group by the Poly-3 test

** P # 0.01

a Number of animals with tissue 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



### Pancreas: The incidences of cytoplasmic alteration

in the pancreatic acini of males exposed to 85.7 or

257.4 mg/L and in all exposed groups of females

were significantly increased (Tables 14, C4, and D4). Cytoplasmic alteration was characterized by depletion

of cytoplasmic zymogen granules from the pancreatic

acinar epithelial cells. The biological significance of

this change was uncertain.

### Sodium Dichromate Dihydrate, NTP TR 546 63



# C hr o m i um 

# T i ssu e 

# D i s t r i bu tion



# S t u d y

As part of the 2-year study, total chromium concentra

tion in selected tissues and excreta were determined in

additional groups of animals (tissue distribution groups)

composed of male rats and female mice (Appendix J).

These animals were treated the same as the animals in

the core study groups with respect to exposure, housing,

and handling. Two days prior to scheduled tissue col

lection, up to 10 animals in each exposure group of both

species were placed in individual metabolism cages for

the separate collection of urine and feces. Animals were

provided undosed drinking water during this time to

allow unabsorbed chromium to be excreted. The 48

- hour

washout period was based on an elimination half-life of

8 to 21 hours (Bragt and van Dura, 1983; Vanoirbeek

et al. , 2003). Increased chromium concentrations in

plasma after the washout period should represent the

chromium entering plasma from the tissues. Insufficient

mouse urine was collected for analysis at most time

points; incomplete separation of urine and feces and low

urine volumes for mice are typical in metabolism cages.

After 48 hours, the animals were euthanized, and eryth

rocytes, plasma, liver, kidney, glandular stomach, and

forestomach were removed for chromium analysis. The

analytical procedure could not differentiate between the

oxidation states of chromium, so the values reported are

for total chromium irrespective of oxidation state. The

complete data sets for rats and mice are presented in

Tables J1 and J2, respectively.

Chromium concentration in tissues from the 172 and

516 mg/L rats and mice were significantly higher than

their respective controls on days 6, 13, 182, and 371,

with the exception of the forestomach on day 6. In the

57.3 mg/L rats, chromium concentrations in the glan

dular stomach were also significantly elevated at all

four time points, while concentrations in the liver and

kidney were elevated at three of the four time points.

In the 57.3 mg/L mice, chromium concentrations in the

liver, kidney, and glandular stomach were significantly elevated at all four time points. In the 14.3 mg/L rats,

chromium concentrations were significantly elevated

above the controls in the glandular stomach on days

6, 13, and 182, in the kidney on days 13, 182, and

371, and in the liver on days 182 and 371. In the 14.3

mg/L mice, chromium concentrations were significantly

elevated in the liver and kidney at all four time points.

In the lowest exposed group, chromium concentrations

in erythrocytes and the forestomach were generally

similar to those in control rats and mice. In all tissues,

the chromium concentration at each time point tended

to increase as the exposure concentration increased;

however, the increases were not proportional to expo

sure concentration as shown for the liver in Figure 5.

A nonproportional increase in tissue concentration with

increasing exposure concentration is consistent with

saturation of an active uptake mechanism for Cr VI. In

accumulating tissues, such as the kidney, liver, fores

tomach, and glandular stomach, chromium concentra

tion increased through day 371, but the increases were

not proportional to the duration of exposure (Figure 6).

In nonaccumulating tissues such as erythrocytes, chro

mium concentration did not increase after day 6. This

observation can be interpreted as the tissues approaching

equilibrium between Cr VI uptake and Cr III diffusion

from the tissues and from cell turnover. In addition,

there was a slight decrease in chromium exposure per

day as the animals aged, based on decreased water con

sumption and increased body weight (Tables 3, 11, G1,

and G4), which was also reflected in lower chromium

concentration in feces at the later time points. In rats

and mice, the tissues with the highest chromium concen

trations were the glandular stomach, kidney, and liver.

Mean concentrations of chromium in the kidney were

greater than those in the liver at most time points for rats,

whereas, the reverse was generally true for mice. Most

of the ingested chromium was excreted in the feces of

both species. The 48-hour feces collection contained up

to 2 mg of chromium for rats and 160 μ g for mice. The

48

- hour urine collection from rats contained up to 20

μ g total chromium, but urine collection from mice was

unsuccessful as noted above.

### 64 Sodium Dichromate Dihydrate, NTP TR 546



### F i gur e 

### 5

Chromium Concentrations on Days 6, 13, 182, and 371 in the Liver of Male Rats Exposed

to Sodium Dichromate Dihydrate in Drinking Water

F i gur e 

### 6

Chromium Concentrations in the Kidney, Liver, Erythrocytes, and Glandular Stomach

of Male Rats Exposed to 516 mg/L Sodium Dichromate Dihydrate in Drinking Water

### P LATE 

### 1

Low magnification of a section of the nasal cavity demonstrating the

location of a squamous cell carcinoma (arrows) arising from the oral

mucosa of the soft palate that has invaded the adjacent submucosal

tissue and surrounded a molar tooth. Male rat exposed to 516 mg/L

sodium dichromate dihydrate in drinking water for 2 years. H&E P LATE 

### 2

Higher magnification of Plate 1 demonstrating the malignant features

of the squamous cell carcinoma. The neoplasm is composed of

pleomorphic islands, cords, and clusters of dysplastic squamous

epithelium (arrows) surrounded by dense proliferative connective

tissue stroma. Oral mucosa (M). H&E

P LATE 

### 3

Squamous cell carcinoma projecting from the dorsal mucosal surface

of the tongue (arrows). The carcinoma is composed of thick papillae

of well-differentiated, mature, keratinized squamous epithelium

(arrows) supported by connective tissue stroma. Female rat exposed

to 14.3 mg/L sodium dichromate dihydrate in drinking water for

2 years. H&E P LATE 

### 4

Higher magnification of Plate 3. Note foci of dysplastic epithelium

(short arrows) within the stroma and extending from the base of the

surface epithelium (arrows). H&E

### P LATE 

### 5

Liver demonstrating histiocytic cellular infiltrates within the

parenchyma (thin arrows) and in portal areas (thick arrows). Female

rat exposed to 516 mg/L sodium dichromate dihydrate in drinking

water for 2 years. H&E P LATE 

### 6

Higher magnification of the histiocytic cellular infiltrates (arrows)

within a portal area. Histiocytes have abundant pale, lightly

eosinophilic, faintly stippled cytoplasm and single, small, dark

peripheral nuclei. Female rat exposed to 516 mg/L sodium

dichromate dihydrate in drinking water for 2 years. H&E

P LATE 

### 7

Liver demonstrating focal chronic inflammation (thin arrows)

composed of a mixture of lymphocytes and small macrophages. Note

also adjacent histiocytic infiltrates within a portal area (thick arrows)

and hepatocytes with fatty change (curved arrow). Female rat

exposed to 516 mg/L sodium dichromate dihydrate in drinking water

for 2 years. H&E P LATE 

### 8

Duodenum demonstrating histiocytic cellular infiltrates (arrows)

within the lamina propria at the tips of the villi. Male rat exposed to

516 mg/L sodium dichromate dihydrate in drinking water for 2 years.

H&E

### P LATE 

### 9

Low magnification of a mesenteric lymph node demonstrating

variably sized clusters and syncytia of histiocytic cellular infiltrates

(arrows) within the parenchyma and sinusoids. Female rat exposed

to 172 mg/L sodium dichromate dihydrate in drinking water for

2 years. H&E P LATE 

### 10



### agnification of Plate 9. Note that the histiocytes have

coalesced to form irregularly sized syncytia (arrows). H&E

P LATE 

### 11

Low magnification demonstrating a well-defined focus of mild

atrophy (arrows) in the sublingual salivary gland. Female rat

exposed to 516 mg/L sodium dichromate dihydrate in drinking water

for 2 years. H&E P LATE 

### 12

Higher magnification of Plate 11. Histologically normal salivary

gland acini (A) are located at the right of the panel and within the

atrophic focus. The atrophic acini (arrows) have lost the pale

secretory material that is clearly evident in the normal acini and are

lined by low cuboidal epithelial cells. Salivary gland ducts (D). H&E

### P LATE 

### 13

Adenoma of the duodenum (arrows) that has distorted and replaced a

focally extensive segment of the mucosa and protruded into the

lumen. Normal mucosa is seen at either side of and opposite the

adenoma. Female mouse exposed to 172 mg/L sodium dichromate

dihydrate in drinking water for 2 years. H&E P LATE 

### 14

Higher magnification of Plate 13 showing a portion of the adenoma

composed of irregular glandular structures (arrows) lined by tall

columnar, hyperchromatic epithelial cells with piling up of the cells

in some areas. H&E

P LATE 

### 15

Large carcinoma of the duodenum (arrows) that has effaced the

mucosa invading the submucosa, muscle layers, and the pancreas.

Male mouse exposed to 257.4 mg/L sodium dichromate dihydrate in

drinking water for 2 years. H&E P LATE 

### 16

Higher magnification of Plate 15 demonstrating dysplastic growth of

atypical cells (arrows) and extensive fibroplasia. H&E

### P LATE 

### 17

Focal epithelial hyperplasia (arrows) occurring in the superficial

mucosa of the duodenum. Female mouse exposed to 172 mg/L

sodium dichromate dihydrate in drinking water for 2 years. H&E P LATE 

### 18

Higher magnification of Plate 17. Villi are lined by increased

numbers of tall columnar, hyperchromatic epithelial cells (arrows)

that are similar to those in the adenomas. H&E

P LATE 

### 19

Normal microscopic anatomy of the duodenum in a control female

mouse in the 2-year drinking water study of sodium dichromate

dihydrate. Note tall, slender villi (arrows) protruding into the lumen.

H&E P LATE 

### 20

Higher magnification of Plate 19. Duodenal villi (arrows) are tall

and slender and lined by a single layer of tall columnar epithelial

cells. H&E

### P LATE 

### 21

Diffuse epithelial hyperplasia in the duodenum. Duodenal villi

(arrows) are short, wide, and blunt. Female mouse exposed to

516 mg/L sodium dichromate dihydrate in drinking water for 2 years.

H&E P LATE 

### 22

Higher magnification of Plate 21. Note the hyperplastic epithelial

cells extending along the villi with piling up in some areas. Note the

histiocytes expanding the lamina propria at the tips of the villi

(arrows). H&E

### 65



### Hexavalent chromium (Cr VI) was nominated for study

because of its occurrence as a contaminant in drinking

water source supplies and the potential for exposure

of large populations of humans. Although Cr VI com

pounds are classified as human carcinogens follow

ing inhalation exposure (IARC, 1990; NTP, 1998),

evidence regarding the carcinogenic potential of Cr

VI compounds following exposure by other routes has

been lacking. The results of 3

- month toxicity studies

of Cr VI administered in the drinking water to F344/N

rats and B6C3F1, BALB/c, and am3 -C57BL/6 mice

as sodium dichromate dihydrate have been published

(NTP, 2007a). Briefly, exposure to sodium dichromate

dihydrate caused a microcytic hypochromic anemia in

rats and mice, which was more severe in rats. The pri

mary nonneoplastic lesions were observed in the glandu

lar stomach of rats exposed to 1,000 mg/L and included

focal ulceration, regenerative epithelial hyperplasia, and

squamous epithelial metaplasia. Additional nonneo

plastic lesions included histiocytic cellular infiltration in

the duodenum of rats and mice, the liver of female rats,

the mesenteric lymph nodes of mice, and the pancreatic

lymph nodes of rats.

The 2

- year studies presented in this Technical Report

were designed after an NTP public meeting on hexava

lent chromium held on July 24, 2002, at the National

Institute of Environmental Health Sciences in Research

Triangle Park, NC, to consider the results of the pre

chronic studies and recommendations from the panel of

scientific experts convened at this meeting (NTP, 2006).

Exposure concentrations for the 2

- year studies were

selected based on these public discussions and careful

review of the data from the 3

- month toxicity studies.

Based on concentrations found in source waters, an

additional low exposure group was added to the 2

- year

studies to provide a concentration that was closer to con

centrations to which humans might be exposed through

the drinking water. The lowest concentration of sodium

dichromate dihydrate (14.3 mg/L) used in the current

2-year studies is equivalent to 5 mg/L chromium and

is less than 10 times the reported hexavalent chromium

concentration of 0.58 mg/L that was found in a ground

water monitoring well in Hinkley, CA (Pellerin and Booker, 2000). A wider spacing of exposures was also

recommended to extend the exposure-response curve.

In the current 2

- year studies, administration of sodium

dichromate dihydrate in drinking water did not affect

survival or produce clinical signs of toxicity in rats or

mice of either sex. Significant exposure-related reduc

tions in body weight gain and water consumption were

observed for male and female rats and mice in the high

est exposure groups. These effects were partly attrib

uted to poor palatability of the dose formulations rather

than direct toxicity from sodium dichromate dihydrate

exposure. Lesions were not observed in the glandular

stomach with increased duration of exposure in contrast

to the 3-month studies, which used higher exposure

concentrations.

Similar to the results from the 3

- month toxicity studies

in rats and mice, exposure-related erythrocyte micro

cytosis, hypochromia, and responsive anemia occurred

in exposed rats. However, there was an amelioration

of the effects by the 12-month time point, suggesting

that the erythron effect was transient and resolved with

time. The transient nature suggests an adaptive response

by the exposed animals. The decreased red blood cell

size and hypochromia is consistent with an ineffective

erythropoiesis and could suggest some perturbation in

iron metabolism and/or hemoglobin production. The

mice were less affected compared to rats and had

only a mild erythrocyte microcytosis. Similar hema

tological effects have been reported for rats and mice

following oral exposure to Cr VI (Kumar and Barthwal,

1991; NTP, 1996a,b, 1997, 2007a; ATSDR, 2000).

Hematological findings of reduced red blood cell, hema

tocrit, and hemoglobin values have also been reported in

a 90-day inhalation toxicity study of soluble hexavalent

chromium trioxide [CrO

3 

### (VI)] in male Sprague-Dawley

rats (Kim et al. , 2004).

In the 3-month toxicity studies (NTP, 2007a) and in the

current 2

- year studies of sodium dichromate dihydrate,

histiocytic cellular infiltration was consistently observed

in several tissues including the liver, duodenum, and

mesenteric and pancreatic lymph nodes of rats and mice. 

# DISCUSSION AND CONCLUSIONS

### 66 Sodium Dichromate Dihydrate, NTP TR 546



### The severities of these lesions were generally minimal

to moderate and were characterized by the presence of

individual, small clusters, and sometimes syncytia of

macrophages. The significance of these lesions is not

known.

In the 2

- year rat study, increased incidences of neo

plasms of the squamous epithelium that lines the oral

mucosa and tongue were observed in male and female

rats, indicating a neoplastic effect of sodium dichromate

dihydrate exposure on epithelial tissues of the upper

alimentary system (oral cavity). There were positive

trends in the incidences of squamous cell carcinoma

of the oral cavity in male and female rats. The inci

dences of squamous cell carcinoma of the oral mucosa

in 516 mg/L males and females were significantly

increased. Two females exposed to 172 mg/L also had

squamous cell carcinoma of the oral mucosa. The inci

dences of squamous cell carcinoma of the oral mucosa in

males and females exceeded the historical control ranges

for drinking water studies and for all routes of admin

istration. The oral mucosa carcinomas were highly

aggressive neoplasms that originated in the oral mucosa

of the palate and invaded the underlying submucosa, the

soft tissue surrounding the nose, and in a few cases, the

tongue, Harderian gland, and brain. A positive trend also

occurred in males and females when incidences of papil

loma and carcinoma of the oral mucosa or tongue were

combined, and the incidences in the 516 mg/L groups

were significantly increased. Nonneoplastic lesions

were not observed in the oral mucosa. Because of the

increased incidences of squamous cell neoplasms of the

oral cavity in both male and female rats and the rarity of

these neoplasms in historical controls, these neoplasms

were considered to be clear evidence of carcinogenicity

of sodium dichromate dihydrate exposure.

In contrast to rats, neoplasms in epithelial tissues of the

lower alimentary system (small intestine) were observed

in mice. The incidences of adenoma of the duode

num were significantly increased in males exposed to

257.4 mg/L and females exposed to 172 or 516 mg/L.

The incidence of adenoma of the jejunum was signifi

cantly increased in females exposed to 516 mg/L. The

incidence of carcinoma was significantly increased in the

duodenum of 516 mg/L female mice. When adenomas

and carcinomas were combined for all sites of the small

intestine, including the duodenum, jejunum, and ileum,

there was a clear exposure response relationship, and

the incidences were statistically significant in the two

highest exposure groups of male and female mice. In addition, low incidences of focal epithelial hyperplasia

were observed in the duodenum and jejunum of male

and female mice. Although not statistically significant,

this lesion was considered a preneoplastic lesion related

to chemical exposure because of the cytologic simi

larities to adenomas. The incidence of diffuse epithelial

cell hyperplasia was also elevated in exposed male and

female mice compared to the control groups. The back

ground incidence of adenoma or carcinoma (combined)

in the small intestine (all sites) of B6C3F1 mice is very

low in NTP studies (Tables C3 and D3). For example,

only one adenoma has been observed in the duodenum

of 350 historical control female mice, and no adenomas

have been observed in the jejunum of 299 historical con

trol male or 350 female mice in drinking water studies.

The combined incidences of adenoma and carcinoma in

57.3 mg/L female mice exceeded the historical control

ranges. Based on these observations, the increased inci

dences of intestinal neoplasms were considered to be

clear evidence of carcinogenicity of sodium dichromate

dihydrate exposure. Only two other chemicals tested by

the NTP, captan and o -nitrotoluene (NCI, 1977; NTP,

2002), have caused increased incidences of neoplasms

in the intestines of male or female mice; neither of these

chemicals were administered in the drinking water. The

2-year study of captan (NCI, 1977) is the only other

study performed by the NTP in B6C3F1 mice in which

both benign and malignant intestinal neoplasms of epi

thelial origin have been definitely attributed to chemical

exposure (Shackelford and Elwell, 1999).

The lower body weights observed in male and female

rats and mice exposed to the two highest exposure con

centrations were partly attributed to poor palatability of

the dosed water and consequent reductions in water con

sumption. However, several lines of evidence suggest

that the animals were not dehydrated. When water con

sumption is adjusted for body weight (data not shown),

dosed male and female rats and female mice drank

approximately the same quantities of water per gram

of body weight as the controls after the first 20 weeks

on study. Male mice exposed to 257.4 mg/L drank less

water per gram of body weight than did the controls

throughout the study. Although mean body weights

and water consumption were reduced in the higher

exposure concentration groups, the average daily doses

(mg sodium dichromate dihydrate per kilogram body

weight) were in the same proportions as the drinking

water concentrations (mg/L) for male and female rats

and mice. Clinical observations related to dehydration

including loss of skin turgor, dry mucous membranes,

### Sodium Dichromate Dihydrate, NTP TR 546 67



### retraction of eyes, hypoactivity, and poor hair coats

were not observed in rats or mice in the 2-year studies of

sodium dichromate dihydrate. Abnormalities in hema

tology and clinical chemistry parameters that typically

indicate dehydration include increases in hematocrit,

urine specific gravity, and serum concentrations of

albumin, total protein, and urea nitrogen. In the current

2

- year studies, hematology and clinical chemistry param

eters were measured in male rats on days 4 and 22 and at

months 3, 6, and 12. Significant decreases in hematocrit

and serum concentrations of albumin and total protein

were observed in males exposed to 516 mg/L. Taken

together, these data suggest that the neoplastic and non

neoplastic effects of sodium dichromate dihydrate were

not associated with dehydration.

There are few human or animal studies in the literature

reporting the potential effects of Cr VI following oral

exposure. However, inhalation exposure to Cr VI com

pounds has been shown to affect the gastrointestinal

system in humans resulting in stomach pain, gastritis,

and stomach and intestinal ulceration (ATSDR, 2000).

Oral exposure also occurs after inhalation of chromium

compounds due to mucociliary clearance and subse

quent swallowing of particulates. Although lung cancer

related to chromium exposure is well documented, there

are conflicting reports in the literature (reviewed by

Cohen et al. , 1993; Costa 1997; ATSDR, 2000; Proctor

et al. , 2002; Costa and Klein 2006; Sedman et al.

, 2006) regarding the occurrence of other types of cancer

attri-buted to chromium exposure. Cohen et al. (1993)

reported that increased incidences of stomach cancer

were seen in numerous epidemiological studies; excesses

of kidney, prostate gland, and bladder cancers were also

seen in workers exposed to Cr VI. Costa (1997) com

piled standardized mortality ratios from several studies

that showed increased incidences of lymphoma and

leukemia and cancers of the prostate gland, stomach,

bladder, brain, and genital system in workers occupa

tionally exposed to chromium. Only one epidemiology

study has specifically addressed human exposure to Cr

VI in drinking water (Zhang and Li, 1987); these authors

reported increased incidences of lung and stomach

tumors in a population consuming water contaminated

by a nearby chromium ore smelting facility, although

chromium exposure was likely by multiple routes (inha

lation, drinking water, food, and soil). Similar to the

results observed in the current 2-year rat study, occupa

tional exposure to Cr VI in the electroplating industry

may also be associated with oral cavity cancer, based

on the diagnosis of oral cavity papillomas in employees of chromium electroplating factories in Czechoslovakia

(ATSDR, 2000). While some reports described above

suggest that Cr VI is a potential human carcinogen via

the oral route of exposure, the USEPA (1998) and IARC

(1990) concluded that there was insufficient data to

make this determination. A review of human and animal

data by Proctor et al. (2002) concluded that Cr VI is not

carcinogenic in humans at permissible drinking water

concentrations.

Nevertheless, based on the studies reviewed above, neo

plasms in the oral cavity and stomach might be expected

in animal carcinogenesis studies. In the current studies,

oral cavity neoplasms were only observed in F344/N

rats. Of 21 chemicals that have caused neoplasms of

the oral cavity in NTP studies, none produced these

neoplasms in male mice and only one, 1,2,3-trichloro

propane, (NTP, 1993) produced oral cavity neoplasms

in female mice. These results demonstrate the greater

sensitivity of the oral cavity of rats to chemical-induced

neoplasms compared to mice. Only one other lifetime

animal carcinogenicity study was identified, in which

Cr VI was administered in the drinking water as potas

sium chromate to three generations of NMRI mice

(Borneff et al. , 1968). In treated mice, two of 66 females

exposed to 9 mg Cr VI/kg developed forestomach carci

noma compared with none of the control mice. This dif

ference was not statistically significant. However, when

benign (9/66 papillomas) and malignant (2/66 carcino

mas) forestomach neoplasms were combined in three

generations of female mice, there was a statistically

significant increase compared to the control group (2/79)

(Sedman et al. , 2006). This study had several limitations

including the use of only one exposure concentration of

Cr VI and high early mortality in the F

0 

### generation as a

result of ectromelia (mousepox) virus.

It has been hypothesized that oral exposure to Cr VI

would not produce an increase in cancer, except perhaps

in the stomach, due to the efficient reducing capacity

of the stomach (De Flora et al. , 1997; De Flora, 2000;

Proctor et al. , 2002). Notably, no neoplasms or non

neoplastic lesions were observed in the forestomach

or glandular stomach of rats or mice. However, the

exposure-related increases in the incidences of neo

plasms in the duodenum and jejunum of mice in the

current 2

- year study suggests that under the conditions

of this study, a portion of the administered Cr VI exited

the stomach unreduced and exerted a carcinogenic

effect on the proximal segments of the small intestine

in mice. Differences in the oral toxicities of hexavalent

### 68 Sodium Dichromate Dihydrate, NTP TR 546



### and trivalent chromium (Cr III) in animal studies pro

vide additional evidence that hexavalent chromium is

not completely converted to trivalent chromium in the

stomach (ATSDR, 2000).

As part of the 2

- year studies, total chromium content

in excreta and selected tissues was determined in addi

tional groups of male rats and female mice (Appendix

J). Since hexavalent chromium as chromate structurally

resembles sulfate and phosphate, it can be taken up by

all cells and organs throughout the body (Costa, 1997).

Chromate and dichromate are in equilibrium in aqueous

solutions, so both forms will be present regardless of the

form initially provided. Animals were removed from

sodium dichromate dihydrate exposure, and urine and

feces were collected for 2 days before the time of tissue

collection. Animals were euthanized, and erythrocytes,

plasma, forestomach, glandular stomach, liver, and kid

ney were removed for total chromium analysis. Current

analytical procedures can not differentiate between

the oxidation states of chromium in biological tissues.

However, the speciation of absorbed chromium can be

inferred from studies comparing Cr VI and Cr III based

on the relative pattern of partitioning and retention of

total chromium in the erythrocytes and tissues compared

to plasma. Cr VI is transported into the erythrocytes and

tissues, while Cr III remains in blood plasma because it

is not a substrate for transport (Proctor et al. , 2002).

Significantly increased tissue concentrations of total

chromium were observed in the erythrocytes, liver,

kidney, forestomach, and glandular stomach of exposed

rats and mice compared to controls indicating that addi

tional Cr VI absorption occurs in these tissues, where it

appears to accumulate with exposure concentration and

time (Tables J1 and J2). The tissue concentrations of

chromium were higher than would be expected based

only on the presence of erythrocytes in the blood of these

tissues. Additional studies have been conducted by the

NTP to analyze the concentrations of chromium in simi

lar tissues following Cr III administration in the diet as

chromium picolinate monohydrate, a dietary supplement

designed to increase Cr III absorption (Figure 7). Taken

together, these studies demonstrate that at equivalent

chromium exposures there were significantly increased

concentrations of chromium in each tissue when the

chromium was administered as Cr VI, compared to when

the chromium was administered as Cr III. For example,

at 25 weeks, chromium concentrations in these tissues were 5 to 16 times higher in animals administered chro

mium as Cr VI than in animals administered chromium

as Cr III. In the current studies, the small intestine was

not collected for total chromium analysis. However,

other reports suggest that hexavalent chromium is also

likely to be absorbed in the small intestine to a greater

extent than trivalent chromium. Infusion of trivalent

chromium into the duodenum or jejunum resulted in 1%

to 2% of the dose being absorbed in humans or 1% to

4% in rats, whereas infusion of hexavalent chromium

resulted in marked increases in absorption in humans

and rats (Donaldson and Barreras, 1966; Febel et al.

, 2001).

The tissue distribution data are consistent with those

reported in the literature where tissue concentrations

of chromium were reported following 11 months of

exposure in male and female rats given chromium in

the drinking water at 25 mg/L in both hexavalent and

trivalent forms (Costa, 1997; Costa and Klein, 2006).

In these studies, concentrations of chromium in the

liver, kidney, and bone were 5.7, 12.0, and 6.4 μ g/g,

respectively, in rats administered hexavalent chromium

as potassium chromate and 0.38, 1.6, and 0.36 μ g/g,

respectively, in rats administered trivalent chromium

as chromium trichloride. The authors concluded that a

significant amount of Cr VI escapes reduction in the red

blood cells and stomach. The study by Davidson et al.

(2004) demonstrating increased susceptibility to skin

cancer induction in hairless mice following coexposure

to ultraviolet light and Cr VI in the drinking water pro

vides additional evidence that Cr VI can have systemic

effects that are distant from the site of exposure.

The postulated mechanism(s) underlying chromiuminduced genotoxicity and carcinogenicity is the subject

of much research and some debate. Cr VI readily enters

cells via nonspecific anion channels, in contrast to Cr III

which cannot easily pass through the cell membrane

(IARC, 1990). Cr VI has been postulated by a number

of authors to exert its genotoxic effects, in part, through

the generation of oxygen radicals (Sugden et al. , 1990;

Sugiyama, 1992; Kasprzak, 1995; Shi et al. , 1999;

Vaglenov et al. , 1999; Benova et al. , 2002; O’Brien

et al. , 2003) during intracellular reduction from the

hexavalent form through the more reactive Cr V and

Cr IV valences to Cr III. It has been suggested that both

enzymatic and nonenzymatic pathways may be involved

in chromium reduction, although at normal physiological

### Sodium Dichromate Dihydrate, NTP TR 546 69



### F i gur e 

### 7

Comparison of Chromium (Cr) Concentrations on Day 182 in Male Rat Tissues

Following Oral Administration as Cr III or Cr VI

* P<0.05 compared to corresponding control group

** P<0.01

§ P<0.001 compared to corresponding chromium picolinate (CP) dose group

a 

### The NTP conducted two studies of Cr, a 2-year bioassay of CP monohydrate in feed (NTP, 2008) and the current 2-year

bioassay of sodium dichromate dihydrate (SDD) in drinking water. To provide a basis of comparison between the two

studies, exposure concentrations were converted to mg Cr/kg body weight using the food and water consumption data for

weeks 1 to 25 of each study. The lowest exposure concentration used in the CP study was 2,000 ppm and 15.2 mg Cr/kg

body weight. The comparable exposure concentration used in the SDD study was 516 mg/L and 8.95 mg Cr/kg body weight.

### 70 Sodium Dichromate Dihydrate, NTP TR 546



### conditions, nonenzymatic reduction is believed to domi

nate (De Flora et al. , 1990; Standeven and Wetterhahn,

1991a). The primary reductants of Cr VI are ascorbic

acid, glutathione, and cysteine, with ascorbic acid being

the main reductant. During reduction of Cr VI to Cr III,

it has been suggested that formation of reactive carbonbased radical species may result in DNA strand breakage

and other types of damage (reviewed by O’Brien et al.

, 2003). Although there are numerous studies providing

experimental evidence in support of the role of reac

tive oxygen species in the genotoxicity of chromium

(Chorvatovicova et al. , 1991, 1993; Sarkar et al. , 1993;

Pattison et al. , 2001; Cemeli et al. , 2003), other studies

raise questions about the relative contribution of this

mechanism (O’Brien et al. , 2003; Zhitkovich, 2005;

Quievryn et al. , 2006).

Cr III, the final product of intracellular reduction of

Cr VI, has been shown to interact directly with DNA and

other macromolecules to induce chromosomal altera

tions and mutational changes (Zhitkovich et al. , 2001,

2002; O’Brien et al. , 2003; Quievryn et al. , 2003, 2006;

Zhitkovich, 2005; Reynolds et al. , 2007). The avail

ability of intracellular ascorbate for Cr VI reduction may

be directly related to the amount of Cr-induced DNA

damage observed (Standeven and Wetterhahn, 1991b;

Quievryn et al. , 2006; Reynolds et al. , 2007). DNA

adducts, DNA

- protein crosslinks, and DNA

- interstrand

crosslinks have all been identified as products of Cr

III-DNA interactions. Detailed discussions of the

types of Cr-DNA adducts that are formed in vivo and

in vitro , along with the biological consequences of

these adducts, including mutagenicity, DNA replica

tion inhibition, and cytotoxicity, and the DNA repair

pathways that may be invoked in response to these kinds

of damage, have recently been provided (O’Brien et al.

, 2003; Zhitkovich, 2005). The relative contributions of the multiple, complex pathways of chromium-induced

genotoxicity are not yet fully understood and continue

to be investigated.

In summary, administration of sodium dichromate dihy

drate in the drinking water to F344/N rats and B6C3F1

mice for 2 years resulted in increased incidences of epi

thelial neoplasms in the alimentary system of male and

female rats and mice. There were increased incidences

of neoplasms of the oral cavity (oral mucosa and tongue)

in rats and exposure concentration-related increased inci

dences of adenoma and carcinoma of the small intestine

in mice. Histiocytic cellular infiltration was observed in

the small intestine, liver, and pancreatic and mesenteric

lymph nodes of rats and mice. There was evidence of

systemic exposure to Cr VI following oral administra

tion in the drinking water based on the tissue distribution

data, toxicity to the hematopoietic system, and the pres

ence of microscopic changes in multiple tissues.



# C on c l us ion s

Under the conditions of these 2-year drinking water

studies, there was clear evidence of carcinogenic activ

ity * of sodium dichromate dihydrate in male and female

F344/N rats based on increased incidences of squamous

cell neoplasms of the oral cavity. There was clear evi

dence of carcinogenic activity of sodium dichromate

dihydrate in male and female B6C3F1 mice based on

increased incidences of neoplasms of the small intestine

(duodenum, jejunum, or ileum).

Exposure to sodium dichromate dihydrate resulted in

histiocytic cellular infiltration in the liver, small intes

tine, and pancreatic and mesenteric lymph nodes of rats

and mice and diffuse epithelial hyperplasia in the small

intestine of male and female mice.

__________

* Explanation of Levels of Evidence of Carcinogenic Activity is on page 12. A summary of the Technical Reports Review Subcommittee

comments and the public discussion on this Technical Report appears on page 14.

### 71



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Verbeken, E.K., Haufroid, V., Lison, D., and Dinsdale, D.

(2003). Kinetics of an intratracheally administered chromium catalyst in rats. J. Toxicol. Environ. Health A 66

, 393-409.

Wahlberg, J.E. (1970). Percutaneous absorption of

trivalent and hexavalent chromium (51Cr) through

excised human and guinea pig skin. Dermatologica

141 , 288-296.

Wahlberg, J.E., and Skog, E. (1965). Percutaneous

absorption of trivalent and hexavalent chromium. Arch.

Dermatol. 92 , 315-318.

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### Sodium Dichromate Dihydrate, NTP TR 546 77



### Wise, S.S., Holmes, A.L., and Wise, J.P., Sr. (2006).

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Zhitkovich, A. (2005). Importance of chromium—DNA

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V. (2001). Non-oxidative mechanisms are responsible

for the induction of mutagenesis by reduction of Cr(VI)

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dependent mutagenesis. Biochemistry 40 , 549-560.

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Health Perspect. 110 (Suppl. 5), 729-731.

### 78 Sodium Dichromate Dihydrate, NTP TR 546

### 79



# APPENDIX A

SUMMARY OF LESIONS IN MALE RATS

IN THE 2-YEAR DRINKING WATER STUDY

OF SODIUM DICHROMATE DIHYDRATE

T ab le 

### A1 Summary of the Incidence of Neoplasms in Male Rats

in the 2-Year Drinking Water Study of Sodium Dichromate Dihydrate

. . . . . . . . . . . . . . . 80

T ab le 

### A2 Statistical Analysis of Primary Neoplasms in Male Rats

in the 2-Year Drinking Water Study of Sodium Dichromate Dihydrate

. . . . . . . . . . . . . . . 84

T ab le 

### A3 Historical Incidence of Oral Cavity Neoplasms in Control Male F344/N Rats

. . . . . . . . . . 90

T ab le 

### A4 Summary of the Incidence of Nonneoplastic Lesions in Male Rats

in the 2-Year Drinking Water Study of Sodium Dichromate Dihydrate

. . . . . . . . . . . . . . . 91

### Sodium Dichromate Dihydrate, NTP TR 546 80



### T ab le 

### A1

Summary of the Incidence of Neoplasms in Male Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate a



### 0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Disposition Summary

Animals initially in study 50 50 50 50 50

Early deaths

Moribund 16 15 16 9 16

Natural deaths 6 5 3 5 4

Survivors

Terminal sacrifice 28 30 30 36 29

Missing 1 1

Animals examined microscopically 50 50 49 50 49



### Alimentary System

Intestine large, cecum (45) (48) (46) (47) (48)

Lipoma 1 (2%)

Intestine large, colon (47) (49) (49) (48) (48)

Leiomyosarcoma 1 (2%)

Intestine small, duodenum (48) (48) (47) (46) (48)

Intestine small, ileum (45) (46) (46) (45) (47)

Intestine small, jejunum (44) (47) (45) (46) (46)

Leiomyoma 1 (2%)

Leiomyosarcoma 1 (2%)

Leiomyosarcoma, metastatic,

intestine, large, colon 1 (2%)

Liver (50) (50) (49) (50) (49)

Hepatocellular adenoma 1 (2%) 2 (4%) 1 (2%)

Leiomyosarcoma, metastatic, spleen 1 (2%)

Mesentery (12) (4) (15) (14) (15)

Hemangioma 1 (7%)

Oral mucosa (50) (50) (49) (50) (49)

Squamous cell carcinoma 6 (12%)

Squamous cell papilloma 1 (2%)

Pancreas (50) (50) (49) (50) (49)

Mixed tumor benign 1 (2%)

Acinus, adenoma 1 (2%) 2 (4%) 4 (8%) 2 (4%) 1 (2%)

Acinus, adenoma, multiple 2 (4%) 1 (2%)

Salivary glands (50) (50) (49) (49) (49)

Schwannoma malignant, metastatic,

peripheral nerve 1 (2%)

Stomach, forestomach (50) (50) (49) (50) (49)

Stomach, glandular (50) (50) (49) (50) (49)

Lipoma 1 (2%) 1 (2%)

Tongue (49) (50) (47) (49) (48)

Squamous cell carcinoma 1 (2%)

Squamous cell papilloma 1 (2%)

Tooth (1) (4)

Squamous cell carcinoma, metastatic,

oral mucosa 1 (25%)



### Cardiovascular System

Blood vessel (4) (3)

Heart (50) (50) (49) (50) (49)

Schwannoma benign 1 (2%)

Schwannoma malignant 1 (2%) 1 (2%)

### 81 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### A1

Summary of the Incidence of Neoplasms in Male Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Endocrine System

Adrenal cortex (50) (50) (49) (50) (49)

Adenoma 1 (2%)

Adrenal medulla (49) (50) (49) (50) (49)

Pheochromocytoma benign 5 (10%) 13 (26%) 10 (20%) 4 (8%) 3 (6%)

Pheochromocytoma malignant 1 (2%) 2 (4%) 3 (6%) 1 (2%)

Bilateral, pheochromocytoma benign 1 (2%) 4 (8%) 1 (2%) 1 (2%)

Islets, pancreatic (50) (50) (49) (50) (49)

Adenoma 4 (8%) 6 (12%) 3 (6%) 7 (14%) 5 (10%)

Adenoma, multiple 1 (2%)

Carcinoma 1 (2%)

Parathyroid gland (46) (46) (46) (49) (48)

Adenoma 1 (2%)

Pituitary gland (50) (50) (49) (50) (49)

Pars distalis, adenoma 15 (30%) 19 (38%) 19 (39%) 10 (20%) 16 (33%)

Pars distalis, adenoma, multiple 1 (2%) 1 (2%)

Pars intermedia, adenoma 1 (2%)

Thyroid gland (50) (50) (49) (50) (49)

C-cell, adenoma 5 (10%) 6 (12%) 3 (6%) 7 (14%) 7 (14%)

C-cell, carcinoma 1 (2%) 2 (4%) 1 (2%) 3 (6%) 2 (4%)

Follicular cell, carcinoma 1 (2%) 3 (6%)



### General Body System

None



### Genital System

Epididymis (50) (50) (49) (50) (49)

Preputial gland (50) (50) (49) (50) (49)

Adenoma 4 (8%) 3 (6%) 3 (6%) 2 (4%) 3 (6%)

Carcinoma 1 (2%) 4 (8%) 7 (14%) 3 (6%) 2 (4%)

Prostate (50) (50) (49) (50) (49)

Adenoma 2 (4%) 2 (4%) 1 (2%)

Seminal vesicle (50) (50) (49) (50) (49)

Testes (50) (50) (49) (50) (49)

Bilateral, interstitial cell, adenoma 41 (82%) 34 (68%) 32 (65%) 39 (78%) 35 (71%)

Interstitial cell, adenoma 7 (14%) 10 (20%) 11 (22%) 10 (20%) 7 (14%)



### Hematopoietic System

Bone marrow (50) (50) (49) (50) (49)

Lymph node (14) (7) (6) (11) (9)

Deep cervical, carcinoma, metastatic,

thyroid gland 1 (11%)

Lymph node, mandibular (5) (2) (2)

Lymph node, mesenteric (49) (50) (49) (50) (49)

Lymph node, pancreatic (32) (34) (34) (36) (33)

Spleen (50) (50) (49) (50) (49)

Hemangiosarcoma 1 (2%)

Leiomyosarcoma 1 (2%)

Thymus (48) (50) (46) (49) (47)

Thymoma malignant 1 (2%)

### Sodium Dichromate Dihydrate, NTP TR 546 82



### T ab le 

### A1

Summary of the Incidence of Neoplasms in Male Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Integumentary System

Mammary gland (50) (49) (48) (50) (49)

Carcinoma 1 (2%) 1 (2%)

Fibroadenoma 2 (4%) 2 (4%) 6 (13%) 3 (6%) 1 (2%)

Fibroadenoma, multiple 1 (2%)

Skin (50) (50) (49) (50) (49)

Basal cell adenoma 2 (4%) 3 (6%) 1 (2%) 1 (2%)

Basal cell carcinoma 2 (4%) 2 (4%)

Keratoacanthoma 2 (4%) 3 (6%) 1 (2%) 4 (8%) 1 (2%)

Squamous cell carcinoma 1 (2%)

Squamous cell papilloma 1 (2%) 1 (2%) 1 (2%)

Trichoepithelioma 1 (2%)

Sebaceous gland, adenoma 1 (2%)

Subcutaneous tissue, fibroma 7 (14%) 11 (22%) 13 (27%) 7 (14%) 7 (14%)

Subcutaneous tissue, fibroma, multiple 1 (2%) 1 (2%) 2 (4%) 1 (2%)

Subcutaneous tissue, fibrosarcoma 1 (2%) 1 (2%) 1 (2%) 1 (2%)

Subcutaneous tissue, fibrous histiocytoma 1 (2%)

Subcutaneous tissue, hemangioma 1 (2%)

Subcutaneous tissue, lipoma 1 (2%) 1 (2%)

Subcutaneous tissue, sarcoma 2 (4%)

Subcutaneous tissue, schwannoma malignant, multiple 1 (2%)



### Musculoskeletal System

Bone (50) (50) (49) (50) (49)

Chordoma 1 (2%)

Osteosarcoma 1 (2%)

Skeletal muscle (3) (2) (2) (1)



### Nervous System

Brain (50) (50) (49) (50) (49)

Astrocytoma malignant 1 (2%)

Peripheral nerve (4) (6) (5) (2) (5)

Schwannoma malignant 1 (20%)

Spinal cord (4) (6) (5) (2) (5)



### Respiratory System

Lung (50) (50) (49) (50) (49)

Alveolar/bronchiolar adenoma 3 (6%) 3 (6%) 2 (4%) 1 (2%) 1 (2%)

Alveolar/bronchiolar adenoma, multiple 1 (2%)

Alveolar/bronchiolar carcinoma 1 (2%) 1 (2%)

Basal cell carcinoma, metastatic, skin 1 (2%)

Carcinoma, metastatic, thyroid gland 1 (2%)

Chordoma, metastatic,

uncertain primary site 1 (2%)

Fibrosarcoma, metastatic, skin 1 (2%)

Osteosarcoma, metastatic,

uncertain primary site 2 (4%)

Sarcoma, metastatic, skin 1 (2%)

Sarcoma, metastatic, uncertain primary site 1 (2%)

Nose (50) (50) (49) (50) (49)

### 83 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### A1

Summary of the Incidence of Neoplasms in Male Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Special Senses System

Eye (50) (50) (49) (50) (49)

Squamous cell carcinoma, metastatic,

oral mucosa 1 (2%)

Harderian gland (50) (50) (49) (50) (49)

Squamous cell carcinoma, metastatic,

oral mucosa 2 (4%)



### Urinary System

Kidney (50) (50) (49) (50) (49)

Urinary bladder (50) (50) (49) (50) (49)



### Systemic Lesions

Multiple organs b (50) (50) (49) (50) (49)

Histiocytic sarcoma 1 (2%)

Leukemia mononuclear 26 (52%) 18 (36%) 22 (45%) 17 (34%) 19 (39%)

Mesothelioma malignant 2 (4%) 2 (4%) 1 (2%)



### Neoplasm Summary

Total animals with primary neoplasms c 50 48 49 50 49

Total primary neoplasms 143 151 162 137 142

Total animals with benign neoplasms 49 47 47 49 49

Total benign neoplasms 107 120 122 105 100

Total animals with malignant neoplasms 29 25 31 29 31

Total malignant neoplasms 36 31 40 32 42

Total animals with metastatic neoplasms 1 3 6

Total metastatic neoplasms 1 3 12

Total animals with malignant neoplasms

of uncertain primary site 1 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

### Sodium Dichromate Dihydrate, NTP TR 546 84



### T ab le 

### A2

Statistical Analysis of Primary Neoplasms in Male Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Adrenal Medulla: Benign Pheochromocytoma

Overall rate a 6/49 (12%) 13/50 (26%) 14/49 (29%) 5/50 (10%) 4/49 (8%)

Adjusted rate b 13.6% 31.1% 33.5% 11.2% 9.3%

Terminal rate c 3/28 (11%) 10/30 (33%) 9/30 (30%) 4/36 (11%) 4/29 (14%)

First incidence (days) 639 687 636 595 729 (T)

Poly-3 test d P=0.018N P=0.042 P=0.024 P=0.493N P=0.386N



### Adrenal Medulla: Malignant Pheochromocytoma

Overall rate 1/49 (2%) 0/50 (0%) 2/49 (4%) 3/50 (6%) 1/49 (2%)

Adjusted rate 2.3% 0.0% 4.9% 6.8% 2.3%

Terminal rate 1/28 (4%) 0/30 (0%) 2/30 (7%) 2/36 (6%) 1/29 (3%)

First incidence (days) 729 (T)

— e 729 (T) 721 729 (T)

Poly-3 test P=0.585 P=0.510N P=0.476 P=0.309 P=0.758



### Adrenal Medulla: Benign or Malignant Pheochromocytoma

Overall rate 7/49 (14%) 13/50 (26%) 15/49 (31%) 7/50 (14%) 5/49 (10%)

Adjusted rate 15.9% 31.1% 35.9% 15.7% 11.6%

Terminal rate 4/28 (14%) 10/30 (33%) 10/30 (33%) 5/36 (14%) 5/29 (17%)

First incidence (days) 639 687 636 595 729 (T)

Poly-3 test P=0.030N P=0.076 P=0.027 P=0.606N P=0.397N



### Lung: Alveolar/bronchiolar Adenoma

Overall rate 4/50 (8%) 3/50 (6%) 2/49 (4%) 1/50 (2%) 1/49 (2%)

Adjusted rate 9.0% 7.2% 4.9% 2.3% 2.3%

Terminal rate 3/28 (11%) 3/30 (10%) 2/30 (7%) 1/36 (3%) 1/29 (3%)

First incidence (days) 677 729 (T) 729 (T) 729 (T) 729 (T)

Poly-3 test P=0.140N P=0.538N P=0.379N P=0.181N P=0.189N



### Lung: Alveolar/bronchiolar Adenoma or Carcinoma

Overall rate 4/50 (8%) 3/50 (6%) 3/49 (6%) 1/50 (2%) 2/49 (4%)

Adjusted rate 9.0% 7.2% 7.4% 2.3% 4.7%

Terminal rate 3/28 (11%) 3/30 (10%) 3/30 (10%) 1/36 (3%) 2/29 (7%)

First incidence (days) 677 729 (T) 729 (T) 729 (T) 729 (T)

Poly-3 test P=0.277N P=0.538N P=0.549N P=0.181N P=0.353N



### Mammary Gland: Fibroadenoma

Overall rate 2/50 (4%) 2/50 (4%) 7/49 (14%) 3/50 (6%) 1/49 (2%)

Adjusted rate 4.5% 4.8% 17.1% 6.8% 2.3%

Terminal rate 1/28 (4%) 1/30 (3%) 6/30 (20%) 3/36 (8%) 1/29 (3%)

First incidence (days) 689 559 652 729 (T) 729 (T)

Poly-3 test P=0.182N P=0.674 P=0.059 P=0.496 P=0.512N



### Mammary Gland: Fibroadenoma or Carcinoma

Overall rate 3/50 (6%) 2/50 (4%) 7/49 (14%) 3/50 (6%) 2/49 (4%)

Adjusted rate 6.8% 4.8% 17.1% 6.8% 4.6%

Terminal rate 2/28 (7%) 1/30 (3%) 6/30 (20%) 3/36 (8%) 1/29 (3%)

First incidence (days) 689 559 652 729 (T) 667

Poly-3 test P=0.279N P=0.525N P=0.124 P=0.659 P=0.513N

### 85 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### A2

Statistical Analysis of Primary Neoplasms in Male Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Oral Cavity (Oral Mucosa): Squamous Cell Carcinoma

Overall rate 0/50 (0%) 0/50 (0%) 0/49 (0%) 0/50 (0%) 6/49 (12%)

Adjusted rate 0.0% 0.0% 0.0% 0.0% 13.6%

Terminal rate 0/28 (0%) 0/30 (0%) 0/30 (0%) 0/36 (0%) 1/29 (3%)

First incidence (days)

— — — — 543

Poly-3 test P<0.001

— f

— — P=0.015



### Oral Cavity (Oral Mucosa or Tongue): Squamous Cell Carcinoma

Overall rate 0/50 (0%) 1/50 (2%) 0/49 (0%) 0/50 (0%) 6/49 (12%)

Adjusted rate 0.0% 2.4% 0.0% 0.0% 13.6%

Terminal rate 0/28 (0%) 1/30 (3%) 0/30 (0%) 0/36 (0%) 1/29 (3%)

First incidence (days)

— 729 (T)

— — 543

Poly-3 test P<0.001 P=0.487

— — P=0.015



### Oral Cavity (Oral Mucosa or Tongue): Squamous Cell Papilloma or Squamous Cell Carcinoma

Overall rate 0/50 (0%) 1/50 (2%) 0/49 (0%) 0/50 (0%) 7/49 (14%)

Adjusted rate 0.0% 2.4% 0.0% 0.0% 15.7%

Terminal rate 0/28 (0%) 1/30 (3%) 0/30 (0%) 0/36 (0%) 1/29 (3%)

First incidence (days)

— 729 (T)

— — 543

Poly-3 test P<0.001 P=0.487

— — P=0.007



### Pancreas: Adenoma

Overall rate 1/50 (2%) 2/50 (4%) 6/49 (12%) 2/50 (4%) 2/49 (4%)

Adjusted rate 2.3% 4.8% 14.6% 4.5% 4.7%

Terminal rate 1/28 (4%) 1/30 (3%) 5/30 (17%) 2/36 (6%) 2/29 (7%)

First incidence (days) 729 (T) 706 560 729 (T) 729 (T)

Poly-3 test P=0.468N P=0.478 P=0.044 P=0.498 P=0.489



### Pancreatic Islets: Adenoma

Overall rate 4/50 (8%) 7/50 (14%) 3/49 (6%) 7/50 (14%) 5/49 (10%)

Adjusted rate 8.9% 16.7% 7.4% 15.8% 11.4%

Terminal rate 2/28 (7%) 5/30 (17%) 3/30 (10%) 6/36 (17%) 3/29 (10%)

First incidence (days) 666 687 729 (T) 692 595

Poly-3 test P=0.550 P=0.222 P=0.552N P=0.254 P=0.486



### Pancreatic Islets: Adenoma or Carcinoma

Overall rate 4/50 (8%) 7/50 (14%) 4/49 (8%) 7/50 (14%) 5/49 (10%)

Adjusted rate 8.9% 16.7% 9.8% 15.8% 11.4%

Terminal rate 2/28 (7%) 5/30 (17%) 3/30 (10%) 6/36 (17%) 3/29 (10%)

First incidence (days) 666 687 636 692 595

Poly-3 test P=0.562N P=0.222 P=0.595 P=0.254 P=0.486



### Pituitary Gland (Pars Distalis): Adenoma

Overall rate 16/50 (32%) 19/50 (38%) 20/49 (41%) 10/50 (20%) 16/49 (33%)

Adjusted rate 35.4% 44.4% 46.1% 22.7% 35.2%

Terminal rate 9/28 (32%) 16/30 (53%) 13/30 (43%) 10/36 (28%) 9/29 (31%)

First incidence (days) 639 477 503 729 (T) 557

Poly-3 test P=0.251N P=0.256 P=0.207 P=0.135N P=0.580N

### Sodium Dichromate Dihydrate, NTP TR 546 86



### T ab le 

### A2

Statistical Analysis of Primary Neoplasms in Male Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Preputial Gland: Adenoma

Overall rate 4/50 (8%) 3/50 (6%) 3/49 (6%) 2/50 (4%) 3/49 (6%)

Adjusted rate 9.0% 7.2% 7.3% 4.5% 7.0%

Terminal rate 3/28 (11%) 1/30 (3%) 1/30 (3%) 2/36 (6%) 3/29 (10%)

First incidence (days) 677 652 652 729 (T) 729 (T)

Poly-3 test P=0.495N P=0.532N P=0.543N P=0.341N P=0.519N



### Preputial Gland: Carcinoma

Overall rate 1/50 (2%) 4/50 (8%) 7/49 (14%) 3/50 (6%) 2/49 (4%)

Adjusted rate 2.3% 9.5% 17.0% 6.8% 4.7%

Terminal rate 1/28 (4%) 2/30 (7%) 5/30 (17%) 3/36 (8%) 2/29 (7%)

First incidence (days) 729 (T) 595 652 729 (T) 729 (T)

Poly-3 test P=0.300N P=0.163 P=0.022 P=0.303 P=0.489



### Preputial Gland: Adenoma or Carcinoma

Overall rate 4/50 (8%) 6/50 (12%) 8/49 (16%) 5/50 (10%) 5/49 (10%)

Adjusted rate 9.0% 14.2% 19.3% 11.3% 11.6%

Terminal rate 3/28 (11%) 3/30 (10%) 5/30 (17%) 5/36 (14%) 5/29 (17%)

First incidence (days) 677 595 652 729 (T) 729 (T)

Poly-3 test P=0.464N P=0.339 P=0.141 P=0.494 P=0.478



### Skin: Keratoacanthoma

Overall rate 2/50 (4%) 3/50 (6%) 1/49 (2%) 4/50 (8%) 1/49 (2%)

Adjusted rate 4.5% 7.2% 2.4% 9.0% 2.3%

Terminal rate 1/28 (4%) 1/30 (3%) 0/30 (0%) 3/36 (8%) 1/29 (3%)

First incidence (days) 587 636 503 549 729 (T)

Poly-3 test P=0.375N P=0.470 P=0.528N P=0.336 P=0.514N



### Skin: Squamous Cell Papilloma or Keratoacanthoma

Overall rate 3/50 (6%) 3/50 (6%) 1/49 (2%) 5/50 (10%) 2/49 (4%)

Adjusted rate 6.7% 7.2% 2.4% 11.2% 4.7%

Terminal rate 1/28 (4%) 1/30 (3%) 0/30 (0%) 4/36 (11%) 2/29 (7%)

First incidence (days) 587 636 503 549 729 (T)

Poly-3 test P=0.517N P=0.632 P=0.334N P=0.355 P=0.519N



### Skin: Basal Cell Adenoma

Overall rate 2/50 (4%) 3/50 (6%) 0/49 (0%) 1/50 (2%) 1/49 (2%)

Adjusted rate 4.5% 7.2% 0.0% 2.3% 2.3%

Terminal rate 2/28 (7%) 2/30 (7%) 0/30 (0%) 1/36 (3%) 1/29 (3%)

First incidence (days) 729 (T) 713

— 729 (T) 729 (T)

Poly-3 test P=0.370N P=0.471 P=0.257N P=0.502N P=0.511N



### Skin: Trichoepithelioma or Basal Cell Adenoma

Overall rate 2/50 (4%) 3/50 (6%) 1/49 (2%) 1/50 (2%) 1/49 (2%)

Adjusted rate 4.5% 7.2% 2.5% 2.3% 2.3%

Terminal rate 2/28 (7%) 2/30 (7%) 1/30 (3%) 1/36 (3%) 1/29 (3%)

First incidence (days) 729 (T) 713 729 (T) 729 (T) 729 (T)

Poly-3 test P=0.314N P=0.471 P=0.530N P=0.502N P=0.511N

### 87 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### A2

Statistical Analysis of Primary Neoplasms in Male Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Skin: Trichoepithelioma, Basal Cell Adenoma, or Basal Cell Carcinoma

Overall rate 2/50 (4%) 5/50 (10%) 3/49 (6%) 1/50 (2%) 1/49 (2%)

Adjusted rate 4.5% 11.8% 7.4% 2.3% 2.3%

Terminal rate 2/28 (7%) 3/30 (10%) 3/30 (10%) 1/36 (3%) 1/29 (3%)

First incidence (days) 729 (T) 345 729 (T) 729 (T) 729 (T)

Poly-3 test P=0.133N P=0.198 P=0.461 P=0.502N P=0.511N



### Skin: Squamous Cell Papilloma, Keratoacanthoma, or Squamous Cell Carcinoma

Overall rate 4/50 (8%) 3/50 (6%) 1/49 (2%) 5/50 (10%) 2/49 (4%)

Adjusted rate 8.9% 7.2% 2.4% 11.2% 4.7%

Terminal rate 1/28 (4%) 1/30 (3%) 0/30 (0%) 4/36 (11%) 2/29 (7%)

First incidence (days) 587 636 503 549 729 (T)

Poly-3 test P=0.429N P=0.539N P=0.205N P=0.496 P=0.358N



### Skin: Squamous Cell Papilloma, Keratoacanthoma, Trichoepithelioma, Basal Cell Adenoma, Basal Cell Carcinoma,

or Squamous Cell Carcinoma

Overall rate 5/50 (10%) 8/50 (16%) 4/49 (8%) 6/50 (12%) 3/49 (6%)

Adjusted rate 11.1% 18.7% 9.7% 13.4% 7.0%

Terminal rate 2/28 (7%) 4/30 (13%) 3/30 (10%) 5/36 (14%) 3/29 (10%)

First incidence (days) 587 345 503 549 729 (T)

Poly-3 test P=0.180N P=0.243 P=0.553N P=0.495 P=0.381N



### Skin (Subcutaneous Tissue): Fibroma

Overall rate 8/50 (16%) 12/50 (24%) 13/49 (27%) 9/50 (18%) 8/49 (16%)

Adjusted rate 17.8% 28.0% 31.3% 20.2% 18.1%

Terminal rate 5/28 (18%) 8/30 (27%) 10/30 (33%) 8/36 (22%) 3/29 (10%)

First incidence (days) 652 584 617 595 609

Poly-3 test P=0.225N P=0.186 P=0.110 P=0.493 P=0.596



### Skin (Subcutaneous Tissue): Fibrous Histiocytoma, Fibrosarcoma, or Sarcoma

Overall rate 3/50 (6%) 1/50 (2%) 1/49 (2%) 1/50 (2%) 1/49 (2%)

Adjusted rate 6.7% 2.4% 2.4% 2.3% 2.3%

Terminal rate 1/28 (4%) 0/30 (0%) 0/30 (0%) 1/36 (3%) 1/29 (3%)

First incidence (days) 696 617 560 729 (T) 729 (T)

Poly-3 test P=0.387N P=0.327N P=0.333N P=0.308N P=0.317N



### Skin (Subcutaneous Tissue): Fibroma, Fibrous Histiocytoma, Fibrosarcoma, or Sarcoma

Overall rate 11/50 (22%) 13/50 (26%) 14/49 (29%) 9/50 (18%) 9/49 (18%)

Adjusted rate 24.4% 30.1% 33.3% 20.2% 20.3%

Terminal rate 6/28 (21%) 8/30 (27%) 10/30 (33%) 8/36 (22%) 4/29 (14%)

First incidence (days) 652 584 560 595 609

Poly-3 test P=0.165N P=0.358 P=0.247 P=0.412N P=0.418N



### Testes: Adenoma

Overall rate 48/50 (96%) 44/50 (88%) 43/49 (88%) 49/50 (98%) 42/49 (86%)

Adjusted rate 97.5% 93.8% 94.5% 99.7% 90.3%

Terminal rate 28/28 (100%) 29/30 (97%) 30/30 (100%) 36/36 (100%) 28/29 (97%)

First incidence (days) 484 454 501 520 543

Poly-3 test P=0.101N P=0.343N P=0.404N P=0.464 P=0.110N

### Sodium Dichromate Dihydrate, NTP TR 546 88



### T ab le 

### A2

Statistical Analysis of Primary Neoplasms in Male Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Thyroid Gland (C-cell): Adenoma

Overall rate 5/50 (10%) 6/50 (12%) 3/49 (6%) 7/50 (14%) 7/49 (14%)

Adjusted rate 11.2% 14.4% 7.3% 15.6% 16.2%

Terminal rate 4/28 (14%) 4/30 (13%) 0/30 (0%) 5/36 (14%) 6/29 (21%)

First incidence (days) 617 687 631 549 652

Poly-3 test P=0.255 P=0.452 P=0.399N P=0.383 P=0.356



### Thyroid Gland (C-cell): Carcinoma

Overall rate 1/50 (2%) 2/50 (4%) 1/49 (2%) 3/50 (6%) 2/49 (4%)

Adjusted rate 2.3% 4.8% 2.4% 6.8% 4.7%

Terminal rate 1/28 (4%) 2/30 (7%) 0/30 (0%) 3/36 (8%) 2/29 (7%)

First incidence (days) 729 (T) 729 (T) 640 729 (T) 729 (T)

Poly-3 test P=0.439 P=0.477 P=0.743 P=0.303 P=0.489



### Thyroid Gland (C-cell): Adenoma or Carcinoma

Overall rate 6/50 (12%) 7/50 (14%) 4/49 (8%) 10/50 (20%) 9/49 (18%)

Adjusted rate 13.4% 16.8% 9.6% 22.2% 20.8%

Terminal rate 5/28 (18%) 5/30 (17%) 0/30 (0%) 8/36 (22%) 8/29 (28%)

First incidence (days) 617 687 631 549 652

Poly-3 test P=0.163 P=0.447 P=0.414N P=0.207 P=0.262



### Thyroid Gland (Follicular Cell): Carcinoma

Overall rate 0/50 (0%) 0/50 (0%) 0/49 (0%) 1/50 (2%) 3/49 (6%)

Adjusted rate 0.0% 0.0% 0.0% 2.3% 6.9%

Terminal rate 0/28 (0%) 0/30 (0%) 0/30 (0%) 1/36 (3%) 0/29 (0%)

First incidence (days)

— — — 729 (T) 605

Poly-3 test P=0.007

— — P=0.499 P=0.116



### All Organs: Mononuclear Cell Leukemia

Overall rate 26/50 (52%) 18/50 (36%) 22/49 (45%) 17/50 (34%) 19/49 (39%)

Adjusted rate 52.6% 41.9% 47.5% 35.2% 42.1%

Terminal rate 9/28 (32%) 12/30 (40%) 11/30 (37%) 8/36 (22%) 10/29 (35%)

First incidence (days) 482 617 272 399 557

Poly-3 test P=0.250N P=0.204N P=0.384N P=0.060N P=0.205N



### All Organs: Benign Neoplasms

Overall rate 49/50 (98%) 47/50 (94%) 47/49 (96%) 49/50 (98%) 49/49 (100%)

Adjusted rate 99.4% 99.4% 99.7% 99.7% 100.0%

Terminal rate 28/28 (100%) 30/30 (100%) 30/30 (100%) 36/36 (100%) 29/29 (100%)

First incidence (days) 484 454 501 520 543

Poly-3 test P=0.859 P=0.998N P=0.997 P=0.995 P=0.993



### All Organs: Malignant Neoplasms

Overall rate 29/50 (58%) 26/50 (52%) 31/49 (63%) 29/50 (58%) 33/49 (67%)

Adjusted rate 58.7% 56.3% 65.3% 60.0% 69.8%

Terminal rate 11/28 (39%) 15/30 (50%) 17/30 (57%) 20/36 (56%) 18/29 (62%)

First incidence (days) 482 337 272 399 543

Poly-3 test P=0.129 P=0.491N P=0.319 P=0.527 P=0.174

### 89 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### A2

Statistical Analysis of Primary Neoplasms in Male Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

All Organs: Benign or Malignant Neoplasms

Overall rate 50/50 (100%) 49/50 (98%) 49/49 (100%) 50/50 (100%) 49/49 (100%)

Adjusted rate 100.0% 99.8% 100.0% 100.0% 100.0%

Terminal rate 28/28 (100%) 30/30 (100%) 30/30 (100%) 36/36 (100%) 29/29 (100%)

First incidence (days) 482 337 272 399 543

Poly-3 test P=1.000 P=1.000N

— — —

(T) Terminal sacrifice

a Number of neoplasm-bearing animals/number of animals examined. Denominator is number of animals examined microscopically for adrenal medulla,

lung, pancreas, pancreatic islets, pituitary gland, preputial gland, testes, and thyroid gland; for other tissues, denominator is number of animals necropsied.

b Poly-3 estimated neoplasm incidence after adjustment for intercurrent mortality

c Observed incidence at terminal kill

d Beneath the control incidence is the P value 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 Poly-3 test accounts for the differential mortality in animals that do not reach

terminal sacrifice. A negative trend or a lower incidence in an exposed group is indicated by N

. e Not applicable; no neoplasms in animal group

f Value of statistic cannot be computed.

### Sodium Dichromate Dihydrate, NTP TR 546 90



### T ab le 

### A3

Historical Incidence of Oral Cavity Neoplasms in Control Male F344/N Rats a



### Incidence in Controls

Oral Mucosa All Sites b



### Study Squamous Cell Carcinoma Papilloma, Squamous Cell Papilloma,

or Squamous Cell Carcinoma

Historical Incidence: Drinking Water Studies

Bromochloroacetic acid 0/50 0/50

Bromodichloromethane 0/50 1/50

Dibromoacetic acid 0/50 0/50

Dibromoacetonitrile 0/50 0/50

Dipropylene glycol 0/50 0/50

Sodium chlorate 0/50 0/50

Sodium dichromate dihydrate 0/50

—



### Overall Historical Incidence: Drinking Water Studies

Total 0/350 1/300 (0.3%)

Mean ± standard deviation 0.3% ± 0.8%

Range (0%-2%)



### Overall Historical Incidence: All Routes

Total (%) 5/1,499 (0.3%) 10/1,449 (0.7%)

Mean ± standard deviation 0.3% ± 0.7% 0.6% ± 0.8%

Range (0%-2%) (0%-2%)

a Data as of March 5, 2007, with sodium dichromate dihydrate data added from Table A1

b All sites includes the oral mucosa, tongue, pharynx, tooth, and gingiva; sodium dichromate dihydrate data not included

### 91 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### A4

Summary of the Incidence of Nonneoplastic Lesions in Male Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate a



### 0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Disposition Summary

Animals initially in study 50 50 50 50 50

Early deaths

Moribund 16 15 16 9 16

Natural deaths 6 5 3 5 4

Survivors

Terminal sacrifice 28 30 30 36 29

Missing 1 1

Animals examined microscopically 50 50 49 50 49



### Alimentary System

Intestine large, cecum (45) (48) (46) (47) (48)

Edema 1 (2%) 1 (2%) 2 (4%) 2 (4%)

Erosion 1 (2%)

Ulcer 1 (2%) 1 (2%)

Intestine large, colon (47) (49) (49) (48) (48)

Edema 1 (2%)

Infiltration cellular, lymphocyte 1 (2%)

Intestine small, duodenum (48) (48) (47) (46) (48)

Erosion 1 (2%) 1 (2%)

Infiltration cellular, histiocyte 6 (13%) 36 (78%) 47 (98%)

Ulcer 1 (2%)

Intestine small, ileum (45) (46) (46) (45) (47)

Hyperplasia 1 (2%)

Lymphoid tissue, hyperplasia 10 (22%) 11 (24%) 9 (20%) 7 (16%) 10 (21%)

Intestine small, jejunum (44) (47) (45) (46) (46)

Hyperplasia 1 (2%)

Epithelium, hyperplasia 1 (2%)

Liver (50) (50) (49) (50) (49)

Angiectasis 1 (2%) 1 (2%)

Basophilic focus 22 (44%) 28 (56%) 29 (59%) 32 (64%) 30 (61%)

Clear cell focus 23 (46%) 19 (38%) 16 (33%) 29 (58%) 25 (51%)

Degeneration, cystic 7 (14%) 3 (6%) 2 (4%) 2 (4%)

Eosinophilic focus 10 (20%) 5 (10%) 4 (8%) 8 (16%) 9 (18%)

Fatty change 12 (24%) 10 (20%) 10 (20%) 8 (16%) 12 (24%)

Hematopoietic cell proliferation 1 (2%) 3 (6%)

Hemorrhage 2 (4%) 1 (2%) 4 (8%) 3 (6%)

Hepatodiaphragmatic nodule 5 (10%) 6 (12%) 6 (12%) 7 (14%) 10 (20%)

Infiltration cellular, histiocyte 1 (2%) 2 (4%) 5 (10%) 34 (69%)

Inflammation, chronic 19 (38%) 25 (50%) 21 (43%) 28 (56%) 26 (53%)

Mixed cell focus 11 (22%) 7 (14%) 5 (10%) 13 (26%) 10 (20%)

Necrosis 3 (6%) 3 (6%) 2 (4%) 1 (2%)

Regeneration 2 (4%) 2 (4%)

Syncytial alteration 1 (2%)

Thrombosis 1 (2%)

Bile duct, hyperplasia 47 (94%) 38 (76%) 33 (67%) 22 (44%) 15 (31%)

Centrilobular, necrosis 8 (16%) 1 (2%) 3 (6%) 2 (4%) 5 (10%)

Hepatocyte, hyperplasia, focal 1 (2%)

Intima, vein, hyperplasia 1 (2%)

Kupffer cell, pigmentation 2 (4%) 1 (2%)

a Number of animals examined microscopically at the site and the number of animals with lesion

### Sodium Dichromate Dihydrate, NTP TR 546 92



### T ab le 

### A4

Summary of the Incidence of Nonneoplastic Lesions in Male Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Alimentary System (continued)

Mesentery (12) (4) (15) (14) (15)

Accessory spleen 1 (8%) 1 (7%) 1 (7%) 1 (7%)

Hemorrhage 1 (7%)

Fat, necrosis 11 (92%) 3 (75%) 10 (67%) 12 (86%) 13 (87%)

Oral mucosa (50) (50) (49) (50) (49)

Pancreas (50) (50) (49) (50) (49)

Atrophy 25 (50%) 16 (32%) 24 (49%) 24 (48%) 31 (63%)

Cyst 9 (18%) 7 (14%) 9 (18%) 9 (18%) 12 (24%)

Acinus, cytoplasmic alteration 1 (2%) 3 (6%)

Acinus, hyperplasia, focal 6 (12%) 10 (20%) 9 (18%) 7 (14%) 9 (18%)

Salivary glands (50) (50) (49) (49) (49)

Atrophy 3 (6%) 1 (2%) 2 (4%) 4 (8%) 3 (6%)

Necrosis 1 (2%) 2 (4%)

Duct, cyst 1 (2%)

Stomach, forestomach (50) (50) (49) (50) (49)

Edema 3 (6%) 3 (6%) 3 (6%)

Erosion 1 (2%) 1 (2%)

Inflammation, chronic active 1 (2%) 1 (2%) 1 (2%)

Ulcer 1 (2%) 3 (6%) 3 (6%) 2 (4%) 1 (2%)

Epithelium, hyperplasia 1 (2%) 2 (4%) 2 (4%) 5 (10%) 1 (2%)

Stomach, glandular (50) (50) (49) (50) (49)

Cyst 1 (2%)

Edema 1 (2%) 1 (2%)

Erosion 8 (16%) 4 (8%) 6 (12%) 5 (10%) 2 (4%)

Hyperplasia 8 (16%) 4 (8%) 9 (18%) 12 (24%) 12 (24%)

Infiltration cellular, lymphocyte 1 (2%)

Ulcer 1 (2%) 3 (6%) 1 (2%) 1 (2%)

Epithelium, glands, dilatation 1 (2%)

Glands, dilatation 1 (2%) 1 (2%) 1 (2%)

Tongue (49) (50) (47) (49) (48)

Fibrosis 1 (2%)

Hemorrhage 1 (2%) 1 (2%)

Hemorrhage, chronic 1 (2%)

Inflammation, chronic 2 (4%) 5 (50%) 6 (13%) 6 (12%) 3 (6%)

Epithelium, hyperplasia 2 (4%) 2 (4%) 1 (2%)

Vein, thrombosis 1 (2%)

Tooth (1) (4)

Malformation 1 (25%)



### Cardiovascular System

Blood vessel (4) (3)

Dilatation 1 (33%)

Heart (50) (50) (49) (50) (49)

Cardiomyopathy 46 (92%) 44 (88%) 44 (90%) 45 (90%) 45 (92%)

Inflammation, chronic 1 (2%)

Thrombosis 5 (10%) 3 (6%) 1 (2%) 2 (4%)

### 93 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### A4

Summary of the Incidence of Nonneoplastic Lesions in Male Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Endocrine System

Adrenal cortex (50) (50) (49) (50) (49)

Accessory adrenal cortical nodule 17 (34%) 18 (36%) 13 (27%) 17 (34%) 8 (16%)

Angiectasis 1 (2%) 1 (2%) 1 (2%)

Degeneration, fatty 7 (14%) 10 (20%) 9 (18%) 7 (14%) 11 (22%)

Hyperplasia, focal 2 (4%) 1 (2%) 6 (12%) 3 (6%)

Hyperplasia, diffuse 1 (2%) 1 (2%)

Hypertrophy 1 (2%)

Hypertrophy, focal 2 (4%) 4 (8%) 4 (8%)

Necrosis 2 (4%) 1 (2%) 1 (2%) 1 (2%)

Adrenal medulla (49) (50) (49) (50) (49)

Hyperplasia 12 (24%) 11 (22%) 17 (35%) 9 (18%) 14 (29%)

Islets, pancreatic (50) (50) (49) (50) (49)

Hyperplasia 2 (4%) 1 (2%) 1 (2%)

Parathyroid gland (46) (46) (46) (49) (48)

Hyperplasia 1 (2%)

Pituitary gland (50) (50) (49) (50) (49)

Pars distalis, angiectasis 2 (4%) 3 (6%) 2 (4%) 5 (10%) 3 (6%)

Pars distalis, cyst 3 (6%) 4 (8%) 7 (14%) 5 (10%) 5 (10%)

Pars distalis, cytoplasmic alteration, focal 2 (4%) 2 (4%) 3 (6%) 2 (4%) 2 (4%)

Pars distalis, hyperplasia 1 (2%) 1 (2%) 1 (2%)

Pars distalis, hyperplasia, focal 12 (24%) 6 (12%) 12 (24%) 14 (28%) 11 (22%)

Pars intermedia, angiectasis 1 (2%) 1 (2%) 2 (4%)

Pars intermedia, cyst 1 (2%) 1 (2%) 2 (4%) 1 (2%) 1 (2%)

Pars intermedia, metaplasia, atypical 1 (2%)

Pars intermedia, pars nervosa, metaplasia, atypical 1 (2%)

Thyroid gland (50) (50) (49) (50) (49)

Ultimobranchial cyst 1 (2%) 2 (4%)

C-cell, hyperplasia 11 (22%) 13 (26%) 18 (37%) 14 (28%) 5 (10%)

Follicle, cyst 1 (2%) 1 (2%) 2 (4%)



### General Body System

None



### Genital System

Epididymis (50) (50) (49) (50) (49)

Granuloma sperm 2 (4%) 1 (2%)

Inflammation, chronic 1 (2%) 2 (4%) 2 (4%) 2 (4%)

Preputial gland (50) (50) (49) (50) (49)

Cyst 1 (2%) 1 (2%) 1 (2%)

Hyperplasia 1 (2%) 1 (2%) 2 (4%) 1 (2%)

Inflammation, chronic 16 (32%) 11 (22%) 13 (27%) 17 (34%) 16 (33%)

Prostate (50) (50) (49) (50) (49)

Cyst 1 (2%)

Inflammation, chronic 19 (38%) 17 (34%) 14 (29%) 8 (16%) 14 (29%)

Epithelium, hyperplasia 7 (14%) 11 (22%) 7 (14%) 7 (14%) 8 (16%)

Seminal vesicle (50) (50) (49) (50) (49)

Inflammation, chronic 1 (2%)

Testes (50) (50) (49) (50) (49)

Germinal epithelium, atrophy 5 (10%) 4 (8%) 6 (12%) 4 (8%) 8 (16%)

Interstitial cell, hyperplasia 4 (8%) 5 (10%) 3 (6%) 4 (8%) 4 (8%)

### Sodium Dichromate Dihydrate, NTP TR 546 94



### T ab le 

### A4

Summary of the Incidence of Nonneoplastic Lesions in Male Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Hematopoietic System

Bone marrow (50) (50) (49) (50) (49)

Hemorrhage 1 (2%)

Hyperplasia 4 (8%) 12 (24%) 7 (14%) 7 (14%) 6 (12%)

Myelofibrosis 2 (4%) 1 (2%) 2 (4%)

Lymph node (14) (7) (6) (11) (9)

Deep cervical, ectasia 2 (22%)

Deep cervical, hyperplasia, lymphoid 2 (22%)

Mediastinal, ectasia 2 (14%) 1 (14%) 1 (9%) 1 (11%)

Mediastinal, hemorrhage 1 (7%) 2 (29%) 1 (17%) 1 (9%) 1 (11%)

Mediastinal, hyperplasia, lymphoid 1 (7%) 1 (14%) 1 (17%) 3 (27%) 2 (22%)

Mediastinal, pigmentation 1 (17%)

Lymph node, mandibular (5) (2) (2)

Ectasia 1 (20%) 1 (50%) 2 (100%)

Lymph node, mesenteric (49) (50) (49) (50) (49)

Hemorrhage 2 (4%) 7 (14%) 9 (18%) 8 (16%) 17 (35%)

Hyperplasia, lymphoid 1 (2%) 6 (12%) 2 (4%) 1 (2%)

Infiltration cellular, histiocyte 13 (27%) 11 (22%) 30 (61%) 39 (78%) 41 (84%)

Lymph node, pancreatic (32) (34) (34) (36) (33)

Congestion 1 (3%)

Ectasia 1 (3%) 1 (3%) 1 (3%)

Hemorrhage 3 (9%) 4 (12%) 2 (6%) 1 (3%)

Hyperplasia, lymphoid 1 (3%)

Infiltration cellular, histiocyte 17 (53%) 22 (65%) 17 (50%) 17 (47%) 25 (76%)

Pigmentation 1 (3%) 1 (3%)

Spleen (50) (50) (49) (50) (49)

Accessory spleen 1 (2%) 2 (4%) 1 (2%)

Fibrosis 2 (4%) 3 (6%) 2 (4%) 1 (2%)

Hematopoietic cell proliferation 18 (36%) 25 (50%) 20 (41%) 20 (40%) 16 (33%)

Hemorrhage 1 (2%) 1 (2%) 1 (2%)

Metaplasia, lipocyte 1 (2%)

Necrosis 4 (8%) 4 (8%) 2 (4%)

Pigmentation 3 (6%) 2 (4%) 1 (2%) 3 (6%)

Lymphoid follicle, atrophy 1 (2%)

Lymphoid follicle, hyperplasia 1 (2%)

Thymus (48) (50) (46) (49) (47)

Atrophy 1 (2%) 1 (2%) 1 (2%)



### Integumentary System

Mammary gland (50) (49) (48) (50) (49)

Hyperplasia 25 (50%) 17 (35%) 19 (40%) 11 (22%) 14 (29%)

Inflammation, granulomatous 1 (2%)

Skin (50) (50) (49) (50) (49)

Angiectasis 1 (2%) 1 (2%)

Cyst 1 (2%) 1 (2%)

Cyst epithelial inclusion 5 (10%) 3 (6%) 2 (4%) 3 (6%) 6 (12%)

Edema 1 (2%)

Hyperkeratosis 5 (10%) 2 (4%) 1 (2%) 4 (8%) 1 (2%)

Epidermis, hyperplasia 1 (2%) 1 (2%)

### 95 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### A4

Summary of the Incidence of Nonneoplastic Lesions in Male Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Musculoskeletal System

Bone (50) (50) (49) (50) (49)

Cranium, osteopetrosis 1 (2%) 2 (4%) 1 (2%)

Femur, osteopetrosis 1 (2%)

Skeletal muscle (3) (2) (2) (1)

Atrophy 1 (100%)



### Nervous System

Brain (50) (50) (49) (50) (49)

Compression 7 (14%) 6 (12%) 9 (18%) 3 (6%) 3 (6%)

Hemorrhage 1 (2%)

Hydrocephalus 1 (2%) 1 (2%)

Peripheral nerve (4) (6) (5) (2) (5)

Atrophy 1 (17%)

Spinal cord (4) (6) (5) (2) (5)

Vacuolization cytoplasmic 1 (25%)



### Respiratory System

Lung (50) (50) (49) (50) (49)

Edema 1 (2%)

Foreign body 1 (2%)

Hemorrhage 10 (20%) 7 (14%) 7 (14%) 6 (12%) 8 (16%)

Infiltration cellular, histiocyte 28 (56%) 27 (54%) 32 (65%) 29 (58%) 33 (67%)

Inflammation, suppurative 1 (2%) 1 (2%)

Inflammation, granulomatous 1 (2%)

Inflammation, chronic 1 (2%) 1 (2%) 1 (2%)

Metaplasia, osseous 1 (2%) 1 (2%) 1 (2%) 1 (2%)

Thrombosis 1 (2%) 1 (2%) 1 (2%)

Alveolar epithelium, hyperplasia 11 (22%) 6 (12%) 4 (8%) 8 (16%) 5 (10%)

Alveolar epithelium, metaplasia, squamous 1 (2%)

Nose (50) (50) (49) (50) (49)

Foreign body 9 (18%) 11 (22%) 9 (18%) 15 (30%) 1 (2%)

Hemorrhage 1 (2%)

Inflammation, chronic 8 (16%) 11 (22%) 8 (16%) 16 (32%) 7 (14%)

Thrombosis 1 (2%)

Nasolacrimal duct, cyst 2 (4%) 1 (2%)

Respiratory epithelium, hyperplasia 5 (10%) 5 (10%) 4 (8%) 11 (22%) 4 (8%)

Respiratory epithelium, metaplasia,

squamous 1 (2%) 3 (6%) 1 (2%)



### Special Senses System

Eye (50) (50) (49) (50) (49)

Cataract 1 (2%) 3 (6%) 2 (4%) 1 (2%) 3 (6%)

Hemorrhage 1 (2%)

Inflammation, chronic 1 (2%) 3 (6%)

Cornea, hyperplasia 1 (2%)

Retina, degeneration 2 (4%) 3 (6%) 4 (8%) 2 (4%) 4 (8%)

Harderian gland (50) (50) (49) (50) (49)

Inflammation, chronic 2 (4%) 1 (2%)

Pigmentation 1 (2%)

### Sodium Dichromate Dihydrate, NTP TR 546 96



### T ab le 

### A4

Summary of the Incidence of Nonneoplastic Lesions in Male Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Urinary System

Kidney (50) (50) (49) (50) (49)

Cyst 2 (4%) 1 (2%) 4 (8%) 1 (2%)

Hydronephrosis 1 (2%)

Infarct 1 (2%)

Infiltration cellular, lipocyte 1 (2%)

Inflammation, chronic 5 (10%) 9 (18%) 8 (16%) 2 (4%) 2 (4%)

Nephropathy 45 (90%) 43 (86%) 45 (92%) 43 (86%) 41 (84%)

Renal tubule, accumulation, hyaline droplet 2 (4%)

Renal tubule, dilatation 3 (6%) 1 (2%)

Renal tubule, hyperplasia 2 (4%)

Renal tubule, necrosis 2 (4%) 1 (2%) 1 (2%) 1 (2%) 1 (2%)

Renal tubule, pigmentation 5 (10%) 1 (2%) 1 (2%) 3 (6%)

Transitional epithelium, hyperplasia 1 (2%)

Urinary bladder (50) (50) (49) (50) (49)

Calculus microscopic observation only 1 (2%)

Edema 1 (2%)

Hemorrhage 1 (2%) 1 (2%)

Inflammation, chronic 1 (2%)

Necrosis 1 (2%)

Transitional epithelium, hyperplasia 1 (2%) 1 (2%)

### 97



# APPENDIX B

SUMMARY OF LESIONS IN FEMALE RATS

IN THE 2-YEAR DRINKING WATER STUDY

OF SODIUM DICHROMATE DIHYDRATE

T ab le 

### B1 Summary of the Incidence of Neoplasms in Female Rats

in the 2-Year Drinking Water Study of Sodium Dichromate Dihydrate

. . . . . . . . . . . . . . . 98

T ab le 

### B2 Statistical Analysis of Primary Neoplasms in Female Rats

in the 2-Year Drinking Water Study of Sodium Dichromate Dihydrate

. . . . . . . . . . . . . . . 102

T ab le 

### B3 Historical Incidence of Oral Cavity Neoplasms in Control Female F344/N Rats

. . . . . . . . 106

T ab le 

### B4 Summary of the Incidence of Nonneoplastic Lesions in Female Rats

in the 2-Year Drinking Water Study of Sodium Dichromate Dihydrate

. . . . . . . . . . . . . . . 107

### Sodium Dichromate Dihydrate, NTP TR 546 98



### T ab le 

### B1

Summary of the Incidence of Neoplasms in Female Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate a



### 0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Disposition Summary

Animals initially in study 50 50 50 50 50

Early deaths

Moribund 12 15 9 10 18

Natural deaths 5 3 9 4 1

Survivors

Died last week of study 1

Terminal sacrifice 32 32 32 36 31

Animals examined microscopically 50 50 50 50 50



### Alimentary System

Intestine large, cecum (46) (47) (48) (47) (50)

Intestine large, colon (49) (49) (49) (48) (50)

Adenoma 1 (2%)

Intestine small, duodenum (46) (49) (48) (46) (50)

Leiomyoma 1 (2%)

Intestine small, ileum (45) (47) (44) (47) (50)

Intestine small, jejunum (46) (46) (44) (45) (49)

Liver (50) (50) (50) (50) (50)

Hepatocellular adenoma 1 (2%) 1 (2%)

Pheochromocytoma malignant, metastatic,

adrenal medulla 1 (2%)

Sarcoma, metastatic, tissue NOS 1 (2%)

Mesentery (11) (13) (12) (15) (10)

Sarcoma 1 (7%)

Oral mucosa (50) (50) (50) (50) (50)

Squamous cell carcinoma 2 (4%) 11 (22%)

Pancreas (50) (50) (50) (50) (50)

Mixed tumor benign 1 (2%)

Salivary glands (50) (50) (50) (50) (50)

Stomach, forestomach (50) (50) (50) (50) (50)

Stomach, glandular (50) (50) (50) (50) (50)

Tongue (45) (49) (48) (48) (48)

Squamous cell carcinoma 1 (2%)

Squamous cell carcinoma, metastatic,

oral mucosa 2 (4%)

Squamous cell papilloma 1 (2%) 1 (2%)



### Cardiovascular System

Heart (50) (50) (50) (50) (50)

Schwannoma malignant 1 (2%) 1 (2%)

### 99 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### B1

Summary of the Incidence of Neoplasms in Female Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Endocrine System

Adrenal cortex (50) (50) (50) (50) (50)

Adenoma 1 (2%) 1 (2%)

Adrenal medulla (49) (50) (49) (50) (50)

Pheochromocytoma benign 2 (4%) 1 (2%) 2 (4%) 4 (8%)

Pheochromocytoma benign, multiple 1 (2%)

Pheochromocytoma malignant 1 (2%) 1 (2%) 1 (2%) 1 (2%)

Pheochromocytoma malignant, multiple 1 (2%)

Islets, pancreatic (50) (50) (50) (50) (50)

Adenoma 2 (4%) 1 (2%) 2 (4%) 2 (4%) 2 (4%)

Adenoma, multiple 1 (2%)

Parathyroid gland (46) (47) (47) (45) (47)

Pituitary gland (50) (50) (50) (50) (49)

Pars distalis, adenoma 26 (52%) 29 (58%) 25 (50%) 21 (42%) 12 (24%)

Pars distalis, adenoma, multiple 2 (4%) 1 (2%)

Pars distalis, carcinoma 2 (4%) 1 (2%) 1 (2%) 1 (2%)

Pars intermedia, adenoma 1 (2%)

Thyroid gland (50) (50) (50) (50) (50)

C-cell, adenoma 8 (16%) 5 (10%) 7 (14%) 4 (8%) 9 (18%)

C-cell, carcinoma 2 (4%) 2 (4%) 2 (4%)

Follicular cell, adenoma 1 (2%)

Follicular cell, carcinoma 1 (2%) 1 (2%) 1 (2%)



### General Body System

Tissue NOS (2)

Abdominal, sarcoma 1 (50%)



### Genital System

Clitoral gland (50) (50) (50) (50) (50)

Adenoma 2 (4%) 9 (18%) 8 (16%) 5 (10%) 4 (8%)

Carcinoma 8 (16%) 8 (16%) 5 (10%) 3 (6%) 5 (10%)

Carcinoma, multiple 3 (6%)

Fibrosarcoma 1 (2%)

Bilateral, adenoma 1 (2%)

Ovary (49) (50) (50) (50) (50)

Granulosa cell tumor benign 1 (2%) 1 (2%)

Uterus (49) (50) (50) (50) (50)

Adenoma 1 (2%)

Leiomyosarcoma 1 (2%)

Polyp stromal 10 (20%) 14 (28%) 13 (26%) 15 (30%) 8 (16%)

Polyp stromal, multiple 1 (2%) 1 (2%) 2 (4%)

Schwannoma malignant 1 (2%) 1 (2%) 1 (2%)

Schwannoma malignant, metastatic, uterus 1 (2%)

Vagina (8) (12) (4) (4) (10)

Polyp 1 (8%)

Schwannoma malignant 1 (10%)

Schwannoma malignant, metastatic, vagina 1 (13%)

### Sodium Dichromate Dihydrate, NTP TR 546 100



### T ab le 

### B1

Summary of the Incidence of Neoplasms in Female Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Hematopoietic System

Bone marrow (50) (50) (49) (50) (50)

Pheochromocytoma malignant, metastatic,

a drenal medulla 1 (2%)

Lymph node (8) (11) (9) (4) (11)

Lymph node, mandibular (4) (3) (2) (3)

Lymph node, mesenteric (50) (50) (50) (50) (50)

Lymph node, pancreatic (29) (36) (30) (34) (33)

Spleen (50) (50) (50) (50) (50)

Pheochromocytoma malignant, metastatic,

adrenal medulla 1 (2%)

Thymus (50) (49) (49) (48) (47)



### Integumentary System

Mammary gland (50) (50) (50) (50) (50)

Adenoma 2 (4%) 1 (2%) 3 (6%)

Carcinoma 3 (6%) 1 (2%) 1 (2%)

Fibroadenoma 13 (26%) 16 (32%) 20 (40%) 19 (38%) 14 (28%)

Fibroadenoma, multiple 24 (48%) 15 (30%) 17 (34%) 11 (22%) 9 (18%)

Skin (50) (50) (50) (50) (50)

Basal cell carcinoma 1 (2%)

Keratoacanthoma 1 (2%)

Sebaceous gland, adenoma 1 (2%) 1 (2%)

Subcutaneous tissue, fibroma 1 (2%) 4 (8%) 1 (2%) 3 (6%)

Subcutaneous tissue, fibroma, multiple 1 (2%)

Subcutaneous tissue, fibrosarcoma 1 (2%)

Subcutaneous tissue, lipoma 1 (2%) 1 (2%)

Subcutaneous tissue, liposarcoma 1 (2%)

Subcutaneous tissue, sarcoma 1 (2%)

Subcutaneous tissue, schwannoma malignant 1 (2%)



### Musculoskeletal System

Bone (50) (50) (50) (50) (50)



### Nervous System

Brain (50) (50) (50) (50) (50)

Carcinoma, metastatic, pituitary gland 1 (2%) 1 (2%) 1 (2%) 1 (2%)

Squamous cell carcinoma, metastatic,

oral mucosa 1 (2%)

### 101 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### B1

Summary of the Incidence of Neoplasms in Female Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Respiratory System

Larynx (1) (1)

Squamous cell carcinoma 1 (100%)

Lung (50) (50) (50) (50) (50)

Alveolar/bronchiolar adenoma 4 (8%) 3 (6%) 2 (4%) 3 (6%) 3 (6%)

Carcinoma, metastatic, clitoral gland 1 (2%)

Carcinoma, metastatic,

uncertain primary site 1 (2%)

Squamous cell carcinoma, metastatic,

oral mucosa 2 (4%)

Nose (50) (50) (50) (50) (50)

Squamous cell carcinoma, metastatic,

oral mucosa 1 (2%)



### Special Senses System

Eye (50) (50) (50) (50) (50)

Harderian gland (50) (50) (50) (50) (50)

Adenoma 1 (2%)

Squamous cell carcinoma, metastatic,

oral mucosa 1 (2%) 1 (2%)

Zymbal’s gland (1) (1)

Carcinoma 1 (100%) 1 (100%)



### Urinary System

Kidney (50) (50) (50) (50) (50)

Urinary bladder (49) (50) (50) (50) (49)

Papilloma 1 (2%)



### Systemic Lesions

Multiple organs b (50) (50) (50) (50) (50)

Leukemia mononuclear 8 (16%) 18 (36%) 13 (26%) 7 (14%) 11 (22%)



### Neoplasm Summary

Moribund 12 15 9 10 18

Total animals with primary neoplasms c 49 48 50 49 47

Total primary neoplasms 126 144 130 114 104

Total animals with benign neoplasms 47 46 47 46 37

Total benign neoplasms 103 103 106 93 68

Total animals with malignant neoplasms 19 30 19 18 30

Total malignant neoplasms 23 41 24 21 36

Total animals with metastatic neoplasms 2 3 2 8

Total metastatic neoplasms 3 5 2 10

Total animals with malignant neoplasms

of uncertain primary site 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

### Sodium Dichromate Dihydrate, NTP TR 546 102



### T ab le 

### B2

Statistical Analysis of Primary Neoplasms in Female Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Adrenal Medulla: Benign Pheochromocytoma

Overall rate a 2/49 (4%) 2/50 (4%) 2/49 (4%) 4/50 (8%) 0/50 (0%)

Adjusted rate b 4.6% 4.6% 4.6% 9.3% 0.0%

Terminal rate c 2/33 (6%) 2/32 (6%) 1/31 (3%) 4/36 (11%) 0/31 (0%)

First incidence (days) 729 (T) 729 (T) 662 729 (T)

— d

Poly-3 test e P=0.200N P=0.692N P=0.693 P=0.334 P=0.240N



### Adrenal Medulla: Benign or Malignant Pheochromocytoma

Overall rate 3/49 (6%) 4/50 (8%) 3/49 (6%) 5/50 (10%) 0/50 (0%)

Adjusted rate 6.9% 9.0% 6.8% 11.6% 0.0%

Terminal rate 3/33 (9%) 3/32 (9%) 1/31 (3%) 5/36 (14%) 0/31 (0%)

First incidence (days) 729 (T) 618 571 729 (T)

— Poly-3 test P=0.084N P=0.509 P=0.658N P=0.352 P=0.121N



### Clitoral Gland: Adenoma

Overall rate 2/50 (4%) 9/50 (18%) 8/50 (16%) 5/50 (10%) 5/50 (10%)

Adjusted rate 4.5% 20.5% 18.0% 11.6% 11.5%

Terminal rate 1/33 (3%) 8/32 (25%) 7/32 (22%) 5/36 (14%) 4/31 (13%)

First incidence (days) 689 689 689 729 (T) 605

Poly-3 test P=0.437N P=0.023 P=0.044 P=0.204 P=0.204



### Clitoral Gland: Carcinoma

Overall rate 8/50 (16%) 11/50 (22%) 5/50 (10%) 3/50 (6%) 5/50 (10%)

Adjusted rate 17.9% 24.6% 11.3% 6.8% 11.7%

Terminal rate 6/33 (18%) 8/32 (25%) 5/32 (16%) 1/36 (3%) 5/31 (16%)

First incidence (days) 654 605 729 (T) 447 729 (T)

Poly-3 test P=0.138N P=0.302 P=0.283N P=0.100N P=0.302N



### Clitoral Gland: Adenoma or Carcinoma

Overall rate 10/50 (20%) 19/50 (38%) 13/50 (26%) 8/50 (16%) 10/50 (20%)

Adjusted rate 22.3% 42.3% 29.3% 18.0% 23.1%

Terminal rate 7/33 (21%) 15/32 (47%) 12/32 (38%) 6/36 (17%) 9/31 (29%)

First incidence (days) 654 605 689 447 605

Poly-3 test P=0.156N P=0.032 P=0.301 P=0.406N P=0.564



### Lung: Alveolar/bronchiolar Adenoma

Overall rate 4/50 (8%) 3/50 (6%) 2/50 (4%) 3/50 (6%) 3/50 (6%)

Adjusted rate 9.0% 6.8% 4.5% 6.9% 7.0%

Terminal rate 4/33 (12%) 3/32 (9%) 2/32 (6%) 3/36 (8%) 2/31 (7%)

First incidence (days) 729 (T) 729 (T) 729 (T) 729 (T) 721

Poly-3 test P=0.579N P=0.507N P=0.339N P=0.514N P=0.518N



### Mammary Gland: Fibroadenoma

Overall rate 37/50 (74%) 31/50 (62%) 37/50 (74%) 30/50 (60%) 23/50 (46%)

Adjusted rate 77.3% 67.4% 79.3% 66.4% 52.1%

Terminal rate 26/33 (79%) 23/32 (72%) 26/32 (81%) 25/36 (69%) 18/31 (58%)

First incidence (days) 489 560 571 559 560

Poly-3 test P=0.003N P=0.191N P=0.505 P=0.165N P=0.007N

### 103 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### B2

Statistical Analysis of Primary Neoplasms in Female Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Mammary Gland: Adenoma

Overall rate 2/50 (4%) 1/50 (2%) 3/50 (6%) 0/50 (0%) 0/50 (0%)

Adjusted rate 4.5% 2.3% 6.7% 0.0% 0.0%

Terminal rate 2/33 (6%) 1/32 (3%) 2/32 (6%) 0/36 (0%) 0/31 (0%)

First incidence (days) 729 (T) 729 (T) 586

— — Poly-3 test P=0.119N P=0.504N P=0.503 P=0.243N P=0.245N



### Mammary Gland: Fibroadenoma or Adenoma

Overall rate 37/50 (74%) 31/50 (62%) 38/50 (76%) 30/50 (60%) 23/50 (46%)

Adjusted rate 77.3% 67.4% 80.6% 66.4% 52.1%

Terminal rate 26/33 (79%) 23/32 (72%) 26/32 (81%) 25/36 (69%) 18/31 (58%)

First incidence (days) 489 560 571 559 560

Poly-3 test P=0.002N P=0.191N P=0.439 P=0.165N P=0.007N



### Mammary Gland: Carcinoma

Overall rate 0/50 (0%) 3/50 (6%) 1/50 (2%) 1/50 (2%) 0/50 (0%)

Adjusted rate 0.0% 6.8% 2.3% 2.3% 0.0%

Terminal rate 0/33 (0%) 2/32 (6%) 1/32 (3%) 1/36 (3%) 0/31 (0%)

First incidence (days)

— 686 729 (T) 729 (T)

— Poly-3 test P=0.236N P=0.117 P=0.499 P=0.495

— f



### Mammary Gland: Adenoma or Carcinoma

Overall rate 2/50 (4%) 4/50 (8%) 4/50 (8%) 1/50 (2%) 0/50 (0%)

Adjusted rate 4.5% 9.1% 9.0% 2.3% 0.0%

Terminal rate 2/33 (6%) 3/32 (9%) 3/32 (9%) 1/36 (3%) 0/31 (0%)

First incidence (days) 729 (T) 686 586 729 (T)

— Poly-3 test P=0.050N P=0.333 P=0.340 P=0.509N P=0.245N



### Mammary Gland: Fibroadenoma, Adenoma, or Carcinoma

Overall rate 37/50 (74%) 31/50 (62%) 39/50 (78%) 30/50 (60%) 23/50 (46%)

Adjusted rate 77.3% 67.4% 82.7% 66.4% 52.1%

Terminal rate 26/33 (79%) 23/32 (72%) 27/32 (84%) 25/36 (69%) 18/31 (58%)

First incidence (days) 489 560 571 559 560

Poly-3 test P=0.002N P=0.191N P=0.335 P=0.165N P=0.007N



### Oral Cavity (Oral Mucosa): Squamous Cell Carcinoma

Overall rate 0/50 (0%) 0/50 (0%) 0/50 (0%) 2/50 (4%) g 11/50 (22%)

Adjusted rate 0.0% 0.0% 0.0% 4.6% 23.9%

Terminal rate 0/33 (0%) 0/32 (0%) 0/32 (0%) 1/36 (3%) 2/31 (7%)

First incidence (days)

— — — 646 506

Poly-3 test P<0.001

— — P=0.233 P<0.001



### Oral Cavity (Oral Mucosa or Tongue): Squamous Cell Papilloma or Squamous Cell Carcinoma

Overall rate 1/50 (2%) 1/50 (2%) 0/50 (0%) 2/50 (4%) 11/50 (22%)

Adjusted rate 2.2% 2.3% 0.0% 4.6% 23.9%

Terminal rate 0/33 (0%) 1/32 (3%) 0/32 (0%) 1/36 (3%) 2/31 (7%)

First incidence (days) 618 729 (T)

— 646 506

Poly-3 test P<0.001 P=0.756 P=0.503N P=0.491 P=0.002

### Sodium Dichromate Dihydrate, NTP TR 546 104



### T ab le 

### B2

Statistical Analysis of Primary Neoplasms in Female Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Pancreatic Islets: Adenoma

Overall rate 2/50 (4%) 1/50 (2%) 2/50 (4%) 3/50 (6%) 2/50 (4%)

Adjusted rate 4.5% 2.3% 4.5% 6.9% 4.7%

Terminal rate 1/33 (3%) 1/32 (3%) 1/32 (3%) 3/36 (8%) 2/31 (7%)

First incidence (days) 721 729 (T) 586 729 (T) 729 (T)

Poly-3 test P=0.491 P=0.504N P=0.692N P=0.488 P=0.682



### Pituitary Gland (Pars Distalis): Adenoma

Overall rate 28/50 (56%) 29/50 (58%) 25/50 (50%) 22/50 (44%) 12/49 (24%)

Adjusted rate 60.5% 61.3% 54.0% 48.3% 27.8%

Terminal rate 20/33 (61%) 18/32 (56%) 16/32 (50%) 16/36 (44%) 9/31 (29%)

First incidence (days) 489 461 534 580 647

Poly-3 test P<0.001N P=0.553 P=0.334N P=0.164N P<0.001N



### Pituitary Gland (Pars Distalis): Adenoma or Carcinoma

Overall rate 30/50 (60%) 30/50 (60%) 25/50 (50%) 23/50 (46%) 13/49 (27%)

Adjusted rate 63.8% 63.4% 54.0% 50.5% 30.1%

Terminal rate 20/33 (61%) 19/32 (59%) 16/32 (50%) 17/36 (47%) 10/31 (32%)

First incidence (days) 489 461 534 580 647

Poly-3 test P<0.001N P=0.571N P=0.221N P=0.135N P<0.001N



### Skin (Subcutaneous Tissue): Fibroma

Overall rate 1/50 (2%) 0/50 (0%) 4/50 (8%) 2/50 (4%) 3/50 (6%)

Adjusted rate 2.3% 0.0% 9.1% 4.6% 6.9%

Terminal rate 1/33 (3%) 0/32 (0%) 4/32 (13%) 2/36 (6%) 2/31 (7%)

First incidence (days) 729 (T)

— 729 (T) 729 (T) 605

Poly-3 test P=0.226 P=0.502N P=0.177 P=0.491 P=0.296



### Skin (Subcutaneous Tissue): Fibroma, Fibrosarcoma, or Sarcoma

Overall rate 1/50 (2%) 1/50 (2%) 4/50 (8%) 3/50 (6%) 3/50 (6%)

Adjusted rate 2.3% 2.2% 9.1% 6.9% 6.9%

Terminal rate 1/33 (3%) 0/32 (0%) 4/32 (13%) 2/36 (6%) 2/31 (7%)

First incidence (days) 729 (T) 461 729 (T) 559 605

Poly-3 test P=0.299 P=0.760N P=0.177 P=0.300 P=0.296



### Thyroid Gland (C-cell): Adenoma

Overall rate 8/50 (16%) 5/50 (10%) 7/50 (14%) 4/50 (8%) 9/50 (18%)

Adjusted rate 17.8% 11.2% 15.8% 9.1% 20.8%

Terminal rate 6/33 (18%) 3/32 (9%) 7/32 (22%) 3/36 (8%) 8/31 (26%)

First incidence (days) 580 560 729 (T) 379 595

Poly-3 test P=0.250 P=0.280N P=0.515N P=0.185N P=0.466



### Thyroid Gland (C-cell): Adenoma or Carcinoma

Overall rate 10/50 (20%) 5/50 (10%) 7/50 (14%) 5/50 (10%) 10/50 (20%)

Adjusted rate 22.0% 11.2% 15.8% 11.3% 23.1%

Terminal rate 7/33 (21%) 3/32 (9%) 7/32 (22%) 4/36 (11%) 9/31 (29%)

First incidence (days) 580 560 729 (T) 379 595

Poly-3 test P=0.232 P=0.135N P=0.316N P=0.140N P=0.555

### 105 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### B2

Statistical Analysis of Primary Neoplasms in Female Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Uterus: Stromal Polyp

Overall rate 10/50 (20%) 15/50 (30%) 14/50 (28%) 17/50 (34%) 8/50 (16%)

Adjusted rate 22.5% 32.7% 31.0% 37.8% 18.1%

Terminal rate 10/33 (30%) 9/32 (28%) 10/32 (31%) 13/36 (36%) 5/31 (16%)

First incidence (days) 729 (T) 554 586 493 461

Poly-3 test P=0.139N P=0.198 P=0.251 P=0.087 P=0.399N



### All Organs: Mononuclear Cell Leukemia

Overall rate 8/50 (16%) 18/50 (36%) 13/50 (26%) 7/50 (14%) 11/50 (22%)

Adjusted rate 17.4% 38.4% 27.9% 15.3% 24.5%

Terminal rate 2/33 (6%) 8/32 (25%) 7/32 (22%) 2/36 (6%) 6/31 (19%)

First incidence (days) 575 387 554 379 472

Poly-3 test P=0.348N P=0.019 P=0.170 P=0.503N P=0.282



### All Organs: Benign Neoplasms

Overall rate 47/50 (94%) 46/50 (92%) 47/50 (94%) 46/50 (92%) 37/50 (74%)

Adjusted rate 95.7% 94.6% 96.8% 94.9% 79.6%

Terminal rate 32/33 (97%) 31/32 (97%) 32/32 (100%) 35/36 (97%) 26/31 (84%)

First incidence (days) 489 461 534 379 461

Poly-3 test P<0.001N P=0.596N P=0.620 P=0.628N P=0.009N



### All Organs: Malignant Neoplasms

Overall rate 20/50 (40%) 30/50 (60%) 19/50 (38%) 18/50 (36%) 31/50 (62%)

Adjusted rate 42.1% 62.4% 39.4% 37.2% 63.1%

Terminal rate 10/33 (30%) 18/32 (56%) 10/32 (31%) 8/36 (22%) 15/31 (48%)

First incidence (days) 575 387 454 379 461

Poly-3 test P=0.057 P=0.034 P=0.475N P=0.389N P=0.029



### All Organs: Benign or Malignant Neoplasms

Overall rate 49/50 (98%) 48/50 (96%) 50/50 (100%) 49/50 (98%) 47/50 (94%)

Adjusted rate 98.0% 96.6% 100.0% 98.0% 94.0%

Terminal rate 32/33 (97%) 31/32 (97%) 32/32 (100%) 35/36 (97%) 28/31 (90%)

First incidence (days) 489 387 454 379 461

Poly-3 test P=0.126N P=0.575N P=0.500 P=0.760 P=0.306N

(T) Terminal sacrifice

a Number of neoplasm-bearing animals/number of animals examined. Denominator is number of animals examined microscopically for adrenal medulla,

clitoral gland, lung, pancreatic islets, pituitary gland, and thyroid gland; for other tissues, denominator is number of animals necropsied.

b Poly-3 estimated neoplasm incidence after adjustment for intercurrent mortality

c Observed incidence at terminal kill

d Not applicable; no neoplasms in animal group

e Beneath the control incidence is the P value 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 Poly-3 test accounts for the differential mortality in animals that do not reach

terminal sacrifice. A negative trend or a lower incidence in an exposed group is indicated by N

. f Value of statistic cannot be computed.

g One animal that had a squamous cell carcinoma of the oral mucosa also had a squamous cell carcinoma of the tongue.

### Sodium Dichromate Dihydrate, NTP TR 546 106



### T ab le 

### B3

Historical Incidence of Oral Cavity Neoplasms in Control Female F344/N Rats a



### Incidence in Controls

Oral Mucosa All Sites b



### Study Squamous Cell Carcinoma Papilloma, Squamous Cell Papilloma, or

Squamous Cell Carcinoma

Historical Incidence: Drinking Water Studies

Bromochloroacetic acid 0/50 1/50

Dibromoacetic acid 0/50 0/50

Dibromoacetonitrile 0/50 1/50

Dipropylene glycol 0/50 1/50

Sodium chlorate 0/50 0/50

Sodium dichromate dihydrate 0/50

—



### Overall Historical Incidences: Drinking Water Studies

Total (%) 0/300 3/250 (1.2%)

Mean ± standard deviation 1.2% ± 1.1%

Range (0%-2%)



### Overall Historical Incidence: All Routes

Total (%) 5/1,400 (0.4%) 14/1,350 (1.0%)

Mean ± standard deviation 0.4% ± 0.8% 1.1% ± 1.6%

Range (0%-2%) (0%-6%)

a Data as of March 5, 2007, with sodium dichromate dihydrate data added from Table B1

b All sites includes the oral mucosa, tongue, pharynx, tooth, and gingiva; sodium dichromate dihydrate data not included

### 107 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### B4

Summary of the Incidence of Nonneoplastic Lesions in Female Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate a



### 0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Disposition Summary

Animals initially in study 50 50 50 50 50

Early deaths

Moribund 12 15 9 10 18

Natural deaths 5 3 9 4 1

Survivors

Died last week of study 1

Terminal sacrifice 32 32 32 36 31

Animals examined microscopically 50 50 50 50 50



### Alimentary System

Intestine large, cecum (46) (47) (48) (47) (50)

Edema 2 (4%) 1 (2%) 1 (2%) 1 (2%)

Hemorrhage 1 (2%)

Intestine large, colon (49) (49) (49) (48) (50)

Intestine small, duodenum (46) (49) (48) (46) (50)

Infiltration cellular, histiocyte 1 (2%) 30 (65%) 47 (94%)

Intestine small, ileum (45) (47) (44) (47) (50)

Lymphatic, hyperplasia 1 (2%)

Lymphoid tissue, hyperplasia 16 (36%) 10 (21%) 8 (18%) 6 (13%) 12 (24%)

Intestine small, jejunum (46) (46) (44) (45) (49)

Liver (50) (50) (50) (50) (50)

Angiectasis 1 (2%) 4 (8%) 2 (4%)

Basophilic focus 45 (90%) 41 (82%) 44 (88%) 47 (94%) 43 (86%)

Clear cell focus 7 (14%) 5 (10%) 7 (14%) 20 (40%) 7 (14%)

Eosinophilic focus 5 (10%) 5 (10%) 5 (10%) 3 (6%) 3 (6%)

Fatty change 3 (6%) 7 (14%) 10 (20%) 13 (26%) 16 (32%)

Hematopoietic cell proliferation 1 (2%) 2 (4%) 3 (6%)

Hemorrhage 1 (2%) 1 (2%) 1 (2%)

Hepatodiaphragmatic nodule 5 (10%) 3 (6%) 9 (18%) 10 (20%) 9 (18%)

Infiltration cellular, histiocyte 1 (2%) 5 (10%) 21 (42%) 42 (84%) 47 (94%)

Inflammation, chronic 12 (24%) 21 (42%) 28 (56%) 35 (70%) 39 (78%)

Mixed cell focus 9 (18%) 6 (12%) 10 (20%) 20 (40%) 18 (36%)

Necrosis 5 (10%) 7 (14%) 4 (8%) 1 (2%)

Regeneration 1 (2%) 1 (2%)

Bile duct, hyperplasia 2 (4%) 5 (10%) 3 (6%) 4 (8%)

Centrilobular, necrosis 4 (8%) 2 (4%) 1 (2%) 2 (4%)

Hepatocyte, syncytial alteration 1 (2%) 1 (2%)

Kupffer cell, pigmentation 1 (2%) 1 (2%)

Lymphatic, infiltration cellular 1 (2%)

Mesentery (11) (13) (12) (15) (10)

Accessory spleen 1 (8%) 1 (7%) 1 (10%)

Fat, necrosis 11 (100%) 10 (77%) 11 (92%) 12 (80%) 9 (90%)

Oral mucosa (50) (50) (50) (50) (50)

Pancreas (50) (50) (50) (50) (50)

Atrophy 6 (12%) 12 (24%) 11 (22%) 9 (18%) 5 (10%)

Cyst 2 (4%) 4 (8%) 3 (6%) 6 (12%) 4 (8%)

Acinus, cytoplasmic alteration 3 (6%)

Acinus, hyperplasia, focal 1 (2%) 1 (2%) 1 (2%)

a Number of animals examined microscopically at the site and the number of animals with lesion

### Sodium Dichromate Dihydrate, NTP TR 546 108



### T ab le 

### B4

Summary of the Incidence of Nonneoplastic Lesions in Female Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Alimentary System (continued)

Salivary glands (50) (50) (50) (50) (50)

Atrophy 9 (18%) 7 (14%) 10 (20%) 17 (34%) 17 (34%)

Fibrosis 1 (2%)

Vacuolization cytoplasmic 1 (2%)

Stomach, forestomach (50) (50) (50) (50) (50)

Edema 1 (2%) 3 (6%) 1 (2%) 2 (4%) 2 (4%)

Erosion 1 (2%) 1 (2%) 1 (2%)

Inflammation, chronic active 1 (2%)

Ulcer 2 (4%) 3 (6%) 2 (4%) 2 (4%) 3 (6%)

Epithelium, hyperplasia 2 (4%) 3 (6%) 4 (8%) 4 (8%) 4 (8%)

Stomach, glandular (50) (50) (50) (50) (50)

Edema 1 (2%) 1 (2%) 1 (2%)

Erosion 2 (4%) 3 (6%) 2 (4%) 1 (2%) 5 (10%)

Hyperplasia 4 (8%) 6 (12%) 4 (8%) 7 (14%) 4 (8%)

Inflammation 1 (2%)

Ulcer 1 (2%) 2 (4%) 1 (2%) 1 (2%) 2 (4%)

Glands, dilatation 1 (2%)

Tongue (45) (49) (48) (48) (48)

Granuloma 2 (4%)

Hemorrhage 1 (2%) 1 (2%)

Inflammation, chronic 8 (18%) 3 (6%) 4 (8%) 14 (29%) 12 (25%)

Ulcer 3 (6%)

Epithelium, hyperplasia 1 (2%) 1 (2%) 1 (2%)



### Cardiovascular System

Heart (50) (50) (50) (50) (50)

Cardiomyopathy 27 (54%) 32 (64%) 35 (70%) 33 (66%) 28 (56%)

Inflammation, chronic 1 (2%)

Necrosis 1 (2%)

Thrombosis 1 (2%) 1 (2%) 2 (4%) 1 (2%)



### Endocrine System

Adrenal cortex (50) (50) (50) (50) (50)

Accessory adrenal cortical nodule 6 (12%) 9 (18%) 10 (20%) 6 (12%) 8 (16%)

Angiectasis 1 (2%) 1 (2%)

Degeneration, fatty 12 (24%) 12 (24%) 17 (34%) 14 (28%) 20 (40%)

Hyperplasia, focal 2 (4%) 6 (12%) 8 (16%) 12 (24%) 6 (12%)

Hypertrophy 1 (2%)

Hypertrophy, focal 4 (8%) 4 (8%) 6 (12%) 1 (2%) 7 (14%)

Necrosis 3 (6%) 2 (4%)

Adrenal medulla (49) (50) (49) (50) (50)

Hyperplasia 2 (4%) 3 (6%) 1 (2%) 2 (4%) 2 (4%)

Islets, pancreatic (50) (50) (50) (50) (50)

Hyperplasia 1 (2%)

Parathyroid gland (46) (47) (47) (45) (47)

Hyperplasia 1 (2%)

### 109 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### B4

Summary of the Incidence of Nonneoplastic Lesions in Female Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Endocrine System (continued)

Pituitary gland (50) (50) (50) (50) (49)

Pars distalis, angiectasis 11 (22%) 6 (12%) 7 (14%) 4 (8%) 3 (6%)

Pars distalis, cyst 18 (36%) 18 (36%) 18 (36%) 18 (36%) 27 (55%)

Pars distalis, cytoplasmic alteration, focal 1 (2%)

Pars distalis, hyperplasia 1 (2%)

Pars distalis, hyperplasia, focal 9 (18%) 8 (16%) 9 (18%) 8 (16%) 10 (20%)

Pars intermedia, angiectasis 1 (2%) 2 (4%)

Pars intermedia, cyst 1 (2%) 3 (6%) 1 (2%) 1 (2%) 3 (6%)

Thyroid gland (50) (50) (50) (50) (50)

Ultimobranchial cyst 2 (4%) 2 (4%)

C-cell, hyperplasia 28 (56%) 28 (56%) 25 (50%) 23 (46%) 16 (32%)

Follicle, cyst 1 (2%)



### General Body System

Tissue NOS (2)



### Genital System

Clitoral gland (50) (50) (50) (50) (50)

Cyst 2 (4%) 2 (4%) 4 (8%) 1 (2%)

Hyperplasia 4 (8%) 1 (2%) 2 (4%) 3 (6%) 1 (2%)

Inflammation 1 (2%)

Inflammation, chronic 3 (6%) 4 (8%) 6 (12%) 8 (16%) 4 (8%)

Ovary (49) (50) (50) (50) (50)

Angiectasis 1 (2%) 1 (2%)

Cyst 9 (18%) 6 (12%) 7 (14%) 10 (20%) 5 (10%)

Uterus (49) (50) (50) (50) (50)

Angiectasis 2 (4%)

Dilatation 1 (2%)

Hemorrhage 1 (2%)

Hyperplasia, cystic 5 (10%) 5 (10%) 4 (8%) 9 (18%) 5 (10%)

Inflammation, chronic 1 (2%)

Vagina (8) (12) (4) (4) (10)

Angiectasis 1 (13%)



### Hematopoietic System

Bone marrow (50) (50) (49) (50) (50)

Hyperplasia 6 (12%) 8 (16%) 7 (14%) 6 (12%) 9 (18%)

Infiltration cellular, histiocyte 1 (2%) 2 (4%)

Myelofibrosis 1 (2%) 1 (2%) 1 (2%)

### Sodium Dichromate Dihydrate, NTP TR 546 110



### T ab le 

### B4

Summary of the Incidence of Nonneoplastic Lesions in Female Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Hematopoietic System (continued)

Lymph node (8) (11) (9) (4) (11)

Hemorrhage 1 (13%) 1 (25%)

Hyperplasia, lymphoid 1 (25%)

Deep cervical, hemorrhage 1 (13%) 1 (11%)

Mediastinal, ectasia 1 (9%) 2 (6%)

Mediastinal, hemorrhage 3 (38%) 4 (36%) 2 (22%) 3 (75%) 4 (36%)

Mediastinal, hyperplasia, lymphoid 2 (25%) 5 (45%) 2 (22%) 1 (25%) 6 (55%)

Mediastinal, pigmentation 1 (13%) 4 (36%) 2 (50%) 1 (9%)

Lymph node, mandibular (4) (3) (2) (3)

Ectasia 1 (33%)

Lymph node, mesenteric (50) (50) (50) (50) (50)

Fibrosis 1 (2%)

Hemorrhage 11 (22%) 13 (26%) 16 (32%) 14 (28%) 21 (42%)

Hyperplasia, lymphoid 2 (4%)

Hyperplasia, reticulum cell 1 (2%) 1 (2%)

Infiltration cellular, histiocyte 21 (42%) 18 (36%) 27 (54%) 36 (72%) 42 (84%)

Lymph node, pancreatic (29) (36) (30) (34) (33)

Hemorrhage 3 (10%) 2 (7%) 4 (12%)

Hyperplasia, lymphoid 2 (6%)

Infiltration cellular, histiocyte 17 (59%) 20 (56%) 23 (77%) 32 (94%) 27 (82%)

Pigmentation 2 (7%) 1 (3%)

Spleen (50) (50) (50) (50) (50)

Accessory spleen 1 (2%) 1 (2%)

Fibrosis 2 (4%)

Hematopoietic cell proliferation 36 (72%) 28 (56%) 38 (76%) 36 (72%) 33 (66%)

Hemorrhage 1 (2%) 1 (2%)

Infiltration cellular, mixed cell 3 (6%)

Necrosis 3 (6%) 1 (2%) 1 (2%) 2 (4%)

Pigmentation 26 (52%) 23 (46%) 13 (26%) 6 (12%) 3 (6%)

Lymphoid follicle, atrophy 1 (2%) 4 (8%)

Lymphoid follicle, hyperplasia 1 (2%) 3 (6%)

Thymus (50) (49) (49) (48) (47)

Atrophy 3 (6%)



### Integumentary System

Mammary gland (50) (50) (50) (50) (50)

Hyperplasia 47 (94%) 50 (100%) 45 (90%) 49 (98%) 44 (88%)

Skin (50) (50) (50) (50) (50)

Cyst epithelial inclusion 1 (2%) 1 (2%)

Edema 1 (2%)

Hyperkeratosis 1 (2%)

Ulcer 1 (2%)



### Musculoskeletal System

Bone (50) (50) (50) (50) (50)

Cranium, osteopetrosis 1 (2%) 1 (2%) 2 (4%)

### 111 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### B4

Summary of the Incidence of Nonneoplastic Lesions in Female Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Nervous System

Brain (50) (50) (50) (50) (50)

Compression 8 (16%) 13 (26%) 15 (30%) 11 (22%) 7 (14%)

Gliosis 1 (2%)

Hemorrhage 1 (2%) 3 (6%) 1 (2%)

Hydrocephalus 2 (4%) 2 (4%)

Necrosis 1 (2%)

Vacuolization cytoplasmic 1 (2%)



### Respiratory System

Larynx (1) (1)

Lung (50) (50) (50) (50) (50)

Edema 1 (2%)

Foreign body 1 (2%) 1 (2%)

Hemorrhage 2 (4%) 4 (8%) 4 (8%) 1 (2%) 2 (4%)

Infiltration cellular, histiocyte 45 (90%) 48 (96%) 42 (84%) 46 (92%) 47 (94%)

Inflammation, chronic 2 (4%) 1 (2%) 3 (6%) 1 (2%)

Alveolar epithelium, hyperplasia 11 (22%) 7 (14%) 12 (24%) 9 (18%) 10 (20%)

Alveolar epithelium, metaplasia, squamous 1 (2%)

Nose (50) (50) (50) (50) (50)

Foreign body 3 (6%) 1 (2%) 1 (2%) 1 (2%) 3 (6%)

Inflammation, chronic 3 (6%) 2 (4%) 3 (6%) 3 (6%)

Nasolacrimal duct, cyst 1 (2%)

Respiratory epithelium, hyperplasia 1 (2%) 1 (2%) 1 (2%) 1 (2%) 2 (4%)



### Special Senses System

Eye (50) (50) (50) (50) (50)

Cataract 2 (4%) 2 (4%) 4 (8%) 1 (2%) 1 (2%)

Inflammation, chronic 3 (6%)

Retina, degeneration 4 (8%) 2 (4%) 3 (6%) 2 (4%) 2 (4%)

Harderian gland (50) (50) (50) (50) (50)

Hemorrhage 1 (2%)

Inflammation, chronic 1 (2%)

Zymbal’s gland (1) (1)



### Urinary System

Kidney (50) (50) (50) (50) (50)

Cyst 1 (2%) 2 (4%)

Glomerulosclerosis 1 (2%)

Hydronephrosis 1 (2%)

Infarct 3 (6%) 1 (2%) 1 (2%) 1 (2%) 4 (8%)

Inflammation, chronic 2 (4%) 1 (2%) 1 (2%) 1 (2%)

Nephropathy 33 (66%) 23 (46%) 32 (64%) 37 (74%) 41 (82%)

Renal tubule, accumulation, hyaline droplet 7 (14%) 4 (8%) 2 (4%) 2 (4%)

Renal tubule, dilatation 1 (2%)

Renal tubule, necrosis 3 (6%) 2 (4%)

Renal tubule, pigmentation 2 (4%) 1 (2%) 1 (2%) 2 (4%)

Transitional epithelium, hyperplasia 3 (6%) 2 (4%) 2 (4%) 1 (2%)

Urinary bladder (49) (50) (50) (50) (49)

Hemorrhage 1 (2%)

### Sodium Dichromate Dihydrate, NTP TR 546 112

### 113



# APPENDIX C

SUMMARY OF LESIONS IN MALE MICE

IN THE 2-YEAR DRINKING WATER STUDY

OF SODIUM DICHROMATE DIHYDRATE

T ab le 

### C1 Summary of the Incidence of Neoplasms in Male Mice

in the 2-Year Drinking Water Study of Sodium Dichromate Dihydrate

. . . . . . . . . . . . . . . 114

T ab le 

### C2 Statistical Analysis of Primary Neoplasms in Male Mice

in the 2-Year Drinking Water Study of Sodium Dichromate Dihydrate

. . . . . . . . . . . . . . . 119

T ab le 

### C3 Historical Incidence of Small Intestine Neoplasms in Control Male B6C3F1 Mice

. . . . . . 123

T ab le 

### C4 Summary of the Incidence of Nonneoplastic Lesions in Male Mice

in the 2-Year Drinking Water Study of Sodium Dichromate Dihydrate

. . . . . . . . . . . . . . . 124

### Sodium Dichromate Dihydrate, NTP TR 546 114



### T ab le 

### C1

Summary of the Incidence of Neoplasms in Male Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate a



### 0 mg/L 14.3 mg/L 28.6 mg/L 85.7 mg/L 257.4 mg/L

Disposition Summary

Animals initially in study 50 50 50 50 50

Early deaths

Moribund 7 5 5 4 3

Natural deaths 10 10 10 8 15

Survivors

Died last week of study 1 1

Terminal sacrifice 32 35 35 38 31

Animals examined microscopically 50 50 50 50 50



### Alimentary System

Esophagus (50) (50) (50) (50) (50)

Squamous cell papilloma 1 (2%)

Gallbladder (47) (45) (44) (44) (39)

Sarcoma, metastatic, uncertain primary site 1 (2%)

Intestine large, cecum (42) (44) (47) (46) (39)

Carcinoma 1 (2%) 1 (2%)

Intestine large, colon (44) (45) (47) (46) (40)

Carcinoma 1 (3%)

Intestine large, rectum (42) (47) (47) (46) (42)

Intestine small, duodenum (39) (43) (45) (48) (40)

Adenoma 1 (3%) 1 (2%) 5 (10%) 9 (23%)

Adenoma, multiple 6 (15%)

Carcinoma 2 (4%) 3 (8%)

Hemangiosarcoma, metastatic, liver 1 (3%)

Hepatoblastoma, metastatic, liver 1 (3%)

Sarcoma, metastatic, mesentery 1 (2%)

Intestine small, ileum (40) (42) (44) (45) (38)

Adenoma 1 (2%)

Carcinoma 1 (2%)

Intestine small, jejunum (41) (42) (42) (46) (38)

Adenoma 3 (8%)

Carcinoma 1 (2%) 1 (2%) 2 (5%)

Carcinoma, multiple 1 (2%)

Sarcoma, metastatic, mesentery 1 (2%)

Liver (50) (50) (50) (50) (50)

Hemangioma 1 (2%)

Hemangiosarcoma 1 (2%) 1 (2%) 5 (10%) 2 (4%) 3 (6%)

Hemangiosarcoma, multiple 1 (2%)

Hepatoblastoma 14 (28%) 7 (14%) 10 (20%) 2 (4%)

Hepatoblastoma, multiple 3 (6%) 1 (2%) 1 (2%)

Hepatocellular adenoma 11 (22%) 12 (24%) 10 (20%) 12 (24%) 18 (36%)

Hepatocellular adenoma, multiple 25 (50%) 21 (42%) 18 (36%) 19 (38%) 10 (20%)

Hepatocellular carcinoma 10 (20%) 14 (28%) 8 (16%) 12 (24%) 14 (28%)

Hepatocellular carcinoma, multiple 4 (8%) 10 (20%) 9 (18%) 4 (8%)

Hepatocholangiocarcinoma 1 (2%)

Ito cell tumor malignant 2 (4%) 1 (2%)

Sarcoma, metastatic, mesentery 1 (2%)

Sarcoma, metastatic, uncertain primary site 1 (2%)

### 115 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### C1

Summary of the Incidence of Neoplasms in Male Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 28.6 mg/L 85.7 mg/L 257.4 mg/L

Alimentary System (continued)

Mesentery (16) (10) (9) (16) (5)

Carcinoma, metastatic, intestine large, cecum 1 (6%)

Fibrosarcoma 1 (6%)

Fibrosarcoma, metastatic, lung 1 (6%)

Hemangiosarcoma 2 (13%)

Hepatoblastoma, metastatic, liver 2 (13%) 2 (20%)

Sarcoma 1 (6%)

Sarcoma, metastatic, uncertain primary site 1 (6%)

Oral mucosa (50) (50) (50) (50) (50)

Pancreas (49) (49) (50) (49) (48)

Fibrosarcoma, metastatic, lung 1 (2%)

Hepatoblastoma, metastatic, liver 2 (4%) 1 (2%)

Sarcoma, metastatic, mesentery 1 (2%)

Salivary glands (49) (50) (49) (50) (50)

Basal cell carcinoma, metastatic, skin 1 (2%)

Stomach, forestomach (50) (50) (48) (50) (48)

Carcinoma, metastatic, intestine large, cecum 1 (2%)

Sarcoma, metastatic, uncertain primary site 1 (2%)

Squamous cell carcinoma 1 (2%)

Squamous cell papilloma 2 (4%)

Stomach, glandular (50) (48) (48) (50) (47)

Hepatoblastoma, metastatic, liver 1 (2%)

Sarcoma, metastatic, mesentery 1 (2%)

Sarcoma, metastatic, uncertain primary site 1 (2%)

Tongue (50) (50) (50) (50) (50)

Tooth (1) (3) (2)



### Cardiovascular System

Blood vessel (2) (1) (1) (1) (1)

Aorta, fibrosarcoma, metastatic, lung 1 (50%)

Heart (50) (50) (50) (50) (50)

Fibrosarcoma, metastatic, lung 1 (2%)

Hemangiosarcoma 1 (2%) 1 (2%)

Osteosarcoma, metastatic, bone 1 (2%)

Sarcoma, metastatic, uncertain primary site 1 (2%)



### Endocrine System

Adrenal cortex (49) (49) (50) (50) (50)

Adenoma 1 (2%) 1 (2%)

Hepatoblastoma, metastatic, liver 2 (4%)

Hepatocellular carcinoma, metastatic, liver 1 (2%)

Sarcoma, metastatic, mesentery 1 (2%)

Capsule, adenoma 7 (14%) 5 (10%) 4 (8%) 6 (12%) 1 (2%)

Adrenal medulla (49) (48) (50) (50) (50)

Pheochromocytoma benign 1 (2%) 1 (2%)

Islets, pancreatic (49) (49) (50) (50) (49)

Adenoma 3 (6%) 1 (2%) 1 (2%)

Parathyroid gland (46) (47) (45) (49) (47)

Pituitary gland (49) (49) (48) (50) (47)

### Sodium Dichromate Dihydrate, NTP TR 546 116



### T ab le 

### C1

Summary of the Incidence of Neoplasms in Male Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate a



### 0 mg/L 14.3 mg/L 28.6 mg/L 85.7 mg/L 257.4 mg/L

Endocrine System (continued)

Thyroid gland (50) (50) (50) (50) (50)

Basal cell carcinoma, metastatic, skin 1 (2%)

Follicular cell, adenoma 1 (2%) 1 (2%) 1 (2%) 1 (2%)

Follicular cell, carcinoma 1 (2%) 1 (2%)



### General Body System

None



### Genital System

Epididymis (50) (50) (50) (50) (50)

Hepatoblastoma, metastatic, liver 1 (2%)

Sarcoma, metastatic, mesentery 1 (2%)

Preputial gland (50) (50) (50) (50) (50)

Prostate (50) (49) (50) (50) (50)

Seminal vesicle (50) (50) (50) (50) (50)

Hepatoblastoma, metastatic, liver 1 (2%)

Sarcoma, metastatic, mesentery 1 (2%)

Testes (50) (50) (50) (50) (50)



### Hematopoietic System

Bone marrow (49) (50) (50) (50) (50)

Hemangiosarcoma 1 (2%) 1 (2%) 1 (2%)

Lymph node (8) (4) (6) (6) (5)

Bronchial, hepatoblastoma, metastatic, liver 1 (17%)

Bronchial, hepatocellular carcinoma, metastatic,

liver 1 (17%)

Bronchial, hepatocholangiocarcinoma, metastatic,

liver 1 (20%)

Iliac, hemangiosarcoma, metastatic, skin 1 (17%)

Mediastinal, alveolar/bronchiolar carcinoma,

metastatic, lung 1 (17%)

Mediastinal, hepatocholangiocarcinoma,

metastatic, liver 1 (20%)

Mediastinal, sarcoma, metastatic,

uncertain primary site 1 (17%)

Renal, hepatoblastoma, metastatic, liver 1 (17%)

Lymph node, mandibular (47) (49) (49) (48) (46)

Hemangiosarcoma 1 (2%)

Hemangiosarcoma, metastatic, spleen 1 (2%)

Lymph node, mesenteric (47) (47) (49) (49) (46)

Carcinoma, metastatic, intestine large, colon 1 (2%)

Hemangioma 1 (2%)

Hemangiosarcoma 1 (2%)

Hepatoblastoma, metastatic, liver 1 (2%)

Sarcoma, metastatic, mesentery 1 (2%)

Lymph node, pancreatic (5) (13) (10) (8) (16)

Hepatoblastoma, metastatic, liver 1 (10%)

### 117 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### C1

Summary of the Incidence of Neoplasms in Male Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 28.6 mg/L 85.7 mg/L 257.4 mg/L

Hematopoietic System (continued)

Spleen (49) (48) (49) (49) (46)

Hemangiosarcoma 2 (4%) 1 (2%) 2 (4%) 2 (4%) 2 (4%)

Thymus (49) (50) (46) (49) (40)

Hepatoblastoma, metastatic, liver 1 (2%)

Osteosarcoma, metastatic, bone 1 (2%)



### Integumentary System

Skin (50) (50) (50) (50) (50)

Basal cell carcinoma 1 (2%)

Hemangioma 1 (2%)

Subcutaneous tissue, fibrosarcoma 1 (2%)

Subcutaneous tissue, hemangiosarcoma 1 (2%) 1 (2%) 1 (2%)



### Musculoskeletal System

Bone (50) (50) (50) (50) (50)

Osteosarcoma 1 (2%)

Skeletal muscle (4) (2) (4) (1)

Hepatoblastoma, metastatic, liver 1 (50%)

Hepatocellular carcinoma, metastatic, liver 1 (25%)

Osteosarcoma, metastatic, bone 1 (25%)

Sarcoma, metastatic, mesentery 1 (100%)



### Nervous System

Brain (50) (50) (50) (50) (50)

Alveolar/bronchiolar carcinoma, metastatic,

lung 1 (2%)



### Respiratory System

Lung (50) (50) (50) (50) (50)

Alveolar/bronchiolar adenoma 13 (26%) 8 (16%) 8 (16%) 6 (12%) 9 (18%)

Alveolar/bronchiolar adenoma, multiple 2 (4%) 1 (2%) 1 (2%) 2 (4%) 2 (4%)

Alveolar/bronchiolar carcinoma 2 (4%) 5 (10%) 10 (20%) 6 (12%) 5 (10%)

Alveolar/bronchiolar carcinoma, multiple 1 (2%) 1 (2%)

Basal cell carcinoma, metastatic, skin 1 (2%)

Carcinoma, metastatic, Harderian gland 1 (2%)

Carcinoma, metastatic, thyroid gland 1 (2%)

Fibrosarcoma 1 (2%)

Hemangiosarcoma 1 (2%)

Hepatoblastoma, metastatic, liver 7 (14%) 3 (6%) 2 (4%)

Hepatocellular carcinoma, metastatic, liver 4 (8%) 7 (14%) 2 (4%) 4 (8%) 7 (14%)

Hepatocholangiocarcinoma, metastatic, liver 1 (2%)

Sarcoma, metastatic, mesentery 1 (2%)

Sarcoma, metastatic, uncertain primary site 1 (2%)

Mediastinum, alveolar/bronchiolar carcinoma,

metastatic, lung 1 (2%)

Mediastinum, osteosarcoma, metastatic, bone 1 (2%)

Nose (50) (50) (50) (50) (50)

### Sodium Dichromate Dihydrate, NTP TR 546 118



### T ab le 

### C1

Summary of the Incidence of Neoplasms in Male Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 28.6 mg/L 85.7 mg/L 257.4 mg/L

Special Senses System

Eye (48) (49) (49) (50) (47)

Harderian gland (50) (50) (49) (50) (50)

Adenoma 6 (12%) 3 (6%) 4 (8%) 3 (6%) 2 (4%)

Basal cell carcinoma, metastatic, skin 1 (2%)

Carcinoma 1 (2%)



### Urinary System

Kidney (50) (50) (50) (50) (49)

Sarcoma, metastatic, mesentery 1 (2%)

Renal tubule, adenoma 1 (2%)

Renal tubule, carcinoma 1 (2%) 1 (2%)

Urethra (1) (1) (1)

Urinary bladder (49) (50) (50) (49) (46)



### Systemic Lesions

Multiple organs b (50) (50) (50) (50) (50)

Histiocytic sarcoma 1 (2%) 1 (2%)

Lymphoma malignant 2 (4%) 2 (4%)

Mesothelioma malignant 2 (4%)



### Neoplasm Summary

Total animals with primary neoplasms c 49 45 47 44 48

Total primary neoplasms 115 99 104 96 107

Total animals with benign neoplasms 42 37 33 42 37

Total benign neoplasms 69 54 49 60 63

Total animals with malignant neoplasms 31 29 36 27 29

Total malignant neoplasms 46 45 55 36 44

Total animals with metastatic neoplasms 15 11 9 8 10

Total metastatic neoplasms 38 17 11 26 13

Total animals with malignant neoplasms

of uncertain primary site 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

### 119 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### C2

Statistical Analysis of Primary Neoplasms in Male Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 28.6 mg/L 85.7 mg/L 257.4 mg/L

Adrenal Cortex: Adenoma

Overall rate a 7/49 (14%) 5/49 (10%) 5/50 (10%) 6/50 (12%) 2/50 (4%)

Adjusted rate b 15.6% 11.4% 11.4% 13.0% 4.6%

Terminal rate c 7/33 (21%) 5/35 (14%) 3/35 (9%) 6/38 (16%) 2/32 (6%)

First incidence (days) 729 (T) 729 (T) 664 729 (T) 729 (T)

Poly-3 test d P=0.091N P=0.398N P=0.395N P=0.476N P=0.083N



### Harderian Gland: Adenoma

Overall rate 6/50 (12%) 3/50 (6%) 4/50 (8%) 3/50 (6%) 2/50 (4%)

Adjusted rate 13.3% 6.8% 9.1% 6.4% 4.6%

Terminal rate 6/33 (18%) 3/35 (9%) 3/35 (9%) 2/38 (5%) 1/32 (3%)

First incidence (days) 729 (T) 729 (T) 623 567 719

Poly-3 test P=0.168N P=0.251N P=0.388N P=0.224N P=0.141N



### Harderian Gland: Adenoma or Carcinoma

Overall rate 6/50 (12%) 4/50 (8%) 4/50 (8%) 3/50 (6%) 2/50 (4%)

Adjusted rate 13.3% 9.0% 9.1% 6.4% 4.6%

Terminal rate 6/33 (18%) 4/35 (11%) 3/35 (9%) 2/38 (5%) 1/32 (3%)

First incidence (days) 729 (T) 729 (T) 623 567 719

Poly-3 test P=0.137N P=0.382N P=0.388N P=0.224N P=0.141N



### Small Intestine (Duodenum): Adenoma

Overall rate 1/50 (2%) 0/50 (0%) 1/50 (2%) 5/50 (10%) 15/50 (30%)

Adjusted rate 2.2% 0.0% 2.3% 10.8% 32.9%

Terminal rate 0/33 (0%) 0/35 (0%) 1/35 (3%) 5/38 (13%) 10/32 (31%)

First incidence (days) 665

— e 729 (T) 729 (T) 451

Poly-3 test P<0.001 P=0.505N P=0.751 P=0.106 P<0.001



### Small Intestine (Duodenum): Carcinoma

Overall rate 0/50 (0%) 0/50 (0%) 0/50 (0%) 2/50 (4%) 3/50 (6%)

Adjusted rate 0.0% 0.0% 0.0% 4.3% 6.8%

Terminal rate 0/33 (0%) 0/35 (0%) 0/35 (0%) 2/38 (5%) 3/32 (9%)

First incidence (days)

— — — 729 (T) 729 (T)

Poly-3 test P=0.011

— f

— P=0.243 P=0.113



### Small Intestine (Jejunum): Adenoma

Overall rate 0/50 (0%) 0/50 (0%) 0/50 (0%) 0/50 (0%) 3/50 (6%)

Adjusted rate 0.0% 0.0% 0.0% 0.0% 6.8%

Terminal rate 0/33 (0%) 0/35 (0%) 0/35 (0%) 0/38 (0%) 2/32 (6%)

First incidence (days)

— — — — 714

Poly-3 test P=0.002

— — — P=0.114



### Small Intestine (Duodenum, Jejunum, or Ileum): Adenoma

Overall rate 1/50 (2%) 1/50 (2%) 1/50 (2%) 5/50 (10%) 17/50 (34%)

Adjusted rate 2.2% 2.3% 2.3% 10.8% 37.2%

Terminal rate 0/33 (0%) 1/35 (3%) 1/35 (3%) 5/38 (13%) 11/32 (34%)

First incidence (days) 665 729 (T) 729 (T) 729 (T) 451

Poly-3 test P<0.001 P=0.755 P=0.751 P=0.106 P<0.001

### Sodium Dichromate Dihydrate, NTP TR 546 120



### T ab le 

### C2

Statistical Analysis of Primary Neoplasms in Male Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 28.6 mg/L 85.7 mg/L 257.4 mg/L

Small Intestine (Duodenum, Jejunum, or Ileum): Carcinoma

Overall rate 0/50 (0%) 2/50 (4%) 1/50 (2%) 3/50 (6%) 5/50 (10%)

Adjusted rate 0.0% 4.5% 2.3% 6.5% 11.4%

Terminal rate 0/33 (0%) 2/35 (6%) 1/35 (3%) 3/38 (8%) 5/32 (16%)

First incidence (days)

— 729 (T) 729 (T) 729 (T) 729 (T)

Poly-3 test P=0.014 P=0.233 P=0.492 P=0.123 P=0.028



### Small Intestine (Duodenum, Jejunum, or Ileum): Adenoma or Carcinoma

Overall rate 1/50 (2%) 3/50 (6%) 2/50 (4%) 7/50 (14%) 20/50 (40%)

Adjusted rate 2.2% 6.8% 4.6% 15.1% 43.8%

Terminal rate 0/33 (0%) 3/35 (9%) 2/35 (6%) 7/38 (18%) 14/32 (44%)

First incidence (days) 665 729 (T) 729 (T) 729 (T) 451

Poly-3 test P<0.001 P=0.296 P=0.485 P=0.032 P<0.001



### Liver: Hemangiosarcoma

Overall rate 1/50 (2%) 1/50 (2%) 5/50 (10%) 2/50 (4%) 4/50 (8%)

Adjusted rate 2.2% 2.3% 11.4% 4.3% 9.1%

Terminal rate 1/33 (3%) 1/35 (3%) 4/35 (11%) 2/38 (5%) 2/32 (6%)

First incidence (days) 729 (T) 729 (T) 621 729 (T) 701

Poly-3 test P=0.202 P=0.756 P=0.094 P=0.509 P=0.171



### Liver: Hepatocellular Adenoma

Overall rate 36/50 (72%) 33/50 (66%) 28/50 (56%) 31/50 (62%) 28/50 (56%)

Adjusted rate 77.2% 71.3% 62.5% 65.7% 60.8%

Terminal rate 29/33 (88%) 28/35 (80%) 24/35 (69%) 28/38 (74%) 22/32 (69%)

First incidence (days) 483 533 482 616 391

Poly-3 test P=0.098N P=0.333N P=0.085N P=0.147N P=0.059N



### Liver: Hepatocellular Carcinoma

Overall rate 14/50 (28%) 24/50 (48%) 17/50 (34%) 12/50 (24%) 18/50 (36%)

Adjusted rate 29.3% 50.2% 36.8% 25.0% 38.0%

Terminal rate 5/33 (15%) 15/35 (43%) 11/35 (31%) 7/38 (18%) 8/32 (25%)

First incidence (days) 435 349 482 567 451

Poly-3 test P=0.504N P=0.028 P=0.291 P=0.405N P=0.251



### Liver: Hepatocellular Adenoma or Carcinoma

Overall rate 42/50 (84%) 42/50 (84%) 33/50 (66%) 37/50 (74%) 41/50 (82%)

Adjusted rate 86.3% 85.5% 71.2% 76.7% 82.9%

Terminal rate 30/33 (91%) 30/35 (86%) 26/35 (74%) 31/38 (82%) 26/32 (81%)

First incidence (days) 435 349 482 567 391

Poly-3 test P=0.544 P=0.570N P=0.050N P=0.159N P=0.422N



### Liver: Hepatoblastoma

Overall rate 17/50 (34%) 8/50 (16%) 11/50 (22%) 2/50 (4%) 0/50 (0%)

Adjusted rate 35.8% 17.7% 24.0% 4.3% 0.0%

Terminal rate 9/33 (27%) 6/35 (17%) 6/35 (17%) 2/38 (5%) 0/32 (0%)

First incidence (days) 435 587 544 729 (T)

— Poly-3 test P<0.001N P=0.039N P=0.153N P<0.001N P<0.001N

### 121 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### C2

Statistical Analysis of Primary Neoplasms in Male Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 28.6 mg/L 85.7 mg/L 257.4 mg/L

Liver: Hepatocellular Carcinoma or Hepatoblastoma

Overall rate 25/50 (50%) 26/50 (52%) 26/50 (52%) 14/50 (28%) 18/50 (36%)

Adjusted rate 51.3% 53.9% 54.0% 29.2% 38.0%

Terminal rate 12/33 (36%) 16/35 (46%) 16/35 (46%) 9/38 (24%) 8/32 (25%)

First incidence (days) 435 349 482 567 451

Poly-3 test P=0.035N P=0.482 P=0.477 P=0.020N P=0.132N



### Liver: Hepatocellular Adenoma, Hepatocellular Carcinoma, or Hepatoblastoma

Overall rate 46/50 (92%) 42/50 (84%) 37/50 (74%) 37/50 (74%) 41/50 (82%)

Adjusted rate 92.7% 85.5% 76.5% 76.7% 82.9%

Terminal rate 30/33 (91%) 30/35 (86%) 26/35 (74%) 31/38 (82%) 26/32 (81%)

First incidence (days) 435 349 482 567 391

Poly-3 test P=0.323N P=0.198N P=0.023N P=0.022N P=0.114N



### Lung: Alveolar/bronchiolar Adenoma

Overall rate 15/50 (30%) 9/50 (18%) 9/50 (18%) 8/50 (16%) 11/50 (22%)

Adjusted rate 32.6% 20.1% 20.5% 17.2% 24.9%

Terminal rate 11/33 (33%) 8/35 (23%) 7/35 (20%) 7/38 (18%) 9/32 (28%)

First incidence (days) 631 533 604 693 632

Poly-3 test P=0.495N P=0.130N P=0.144N P=0.069N P=0.282N



### Lung: Alveolar/bronchiolar Carcinoma

Overall rate 3/50 (6%) 5/50 (10%) 11/50 (22%) 6/50 (12%) 5/50 (10%)

Adjusted rate 6.6% 11.2% 25.0% 13.0% 11.3%

Terminal rate 2/33 (6%) 3/35 (9%) 8/35 (23%) 6/38 (16%) 4/32 (13%)

First incidence (days) 631 646 587 729 (T) 600

Poly-3 test P=0.481N P=0.348 P=0.015 P=0.250 P=0.342



### Lung: Alveolar/bronchiolar Adenoma or Carcinoma

Overall rate 16/50 (32%) 12/50 (24%) 16/50 (32%) 13/50 (26%) 16/50 (32%)

Adjusted rate 34.7% 26.4% 36.0% 28.0% 35.8%

Terminal rate 12/33 (36%) 9/35 (26%) 12/35 (34%) 12/38 (32%) 13/32 (41%)

First incidence (days) 631 533 587 693 600

Poly-3 test P=0.394 P=0.262N P=0.536 P=0.317N P=0.546



### Pancreatic Islets: Adenoma

Overall rate 3/49 (6%) 1/49 (2%) 1/50 (2%) 0/50 (0%) 0/49 (0%)

Adjusted rate 6.6% 2.3% 2.3% 0.0% 0.0%

Terminal rate 2/33 (6%) 0/35 (0%) 0/35 (0%) 0/38 (0%) 0/32 (0%)

First incidence (days) 435 588 482

— — Poly-3 test P=0.107N P=0.319N P=0.317N P=0.116N P=0.128N



### All Organs: Hemangiosarcoma

Overall rate 4/50 (8%) 1/50 (2%) 6/50 (12%) 6/50 (12%) 6/50 (12%)

Adjusted rate 8.9% 2.3% 13.7% 12.8% 13.6%

Terminal rate 4/33 (12%) 1/35 (3%) 5/35 (14%) 4/38 (11%) 4/32 (13%)

First incidence (days) 729 (T) 729 (T) 621 645 701

Poly-3 test P=0.181 P=0.185N P=0.350 P=0.392 P=0.354

### Sodium Dichromate Dihydrate, NTP TR 546 122



### T ab le 

### C2

Statistical Analysis of Primary Neoplasms in Male Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 28.6 mg/L 85.7 mg/L 257.4 mg/L

All Organs: Hemangioma or Hemangiosarcoma

Overall rate 4/50 (8%) 2/50 (4%) 6/50 (12%) 8/50 (16%) 6/50 (12%)

Adjusted rate 8.9% 4.5% 13.7% 17.0% 13.6%

Terminal rate 4/33 (12%) 2/35 (6%) 5/35 (14%) 5/38 (13%) 4/32 (13%)

First incidence (days) 729 (T) 729 (T) 621 645 701

Poly-3 test P=0.222 P=0.346N P=0.350 P=0.197 P=0.354



### All Organs: Benign Neoplasms

Overall rate 42/50 (84%) 37/50 (74%) 33/50 (66%) 42/50 (84%) 37/50 (74%)

Adjusted rate 86.9% 79.1% 72.7% 86.3% 77.0%

Terminal rate 31/33 (94%) 31/35 (89%) 27/35 (77%) 35/38 (92%) 25/32 (78%)

First incidence (days) 435 533 482 545 391

Poly-3 test P=0.334N P=0.214N P=0.058N P=0.587N P=0.146N



### All Organs: Malignant Neoplasms

Overall rate 31/50 (62%) 29/50 (58%) 36/50 (72%) 28/50 (56%) 29/50 (58%)

Adjusted rate 63.2% 60.1% 74.1% 57.2% 61.0%

Terminal rate 17/33 (52%) 19/35 (54%) 24/35 (69%) 20/38 (53%) 17/32 (53%)

First incidence (days) 435 349 482 545 451

Poly-3 test P=0.337N P=0.457N P=0.172 P=0.344N P=0.493N



### All Organs: Benign or Malignant Neoplasms

Overall rate 49/50 (98%) 45/50 (90%) 47/50 (94%) 45/50 (90%) 48/50 (96%)

Adjusted rate 98.0% 91.6% 95.9% 91.5% 96.0%

Terminal rate 32/33 (97%) 33/35 (94%) 33/35 (94%) 36/38 (95%) 30/32 (94%)

First incidence (days) 435 349 482 545 391

Poly-3 test P=0.552 P=0.146N P=0.493N P=0.145N P=0.500N

(T) Terminal sacrifice

a Number of neoplasm-bearing animals/number of animals examined. Denominator is number of animals examined microscopically for adrenal cortex, liver,

lung, and pancreatic islets; for other tissues, denominator is number of animals necropsied.

b Poly-3 estimated neoplasm incidence after adjustment for intercurrent mortality

c Observed incidence at terminal kill

d Beneath the control incidence is the P value 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 Poly-3 test accounts for the differential mortality in animals that do not reach terminal

sacrifice. A negative trend or a lower incidence in an exposed group is indicated by N

. e Not applicable; no neoplasms in animal group

f Value of statistic cannot be computed.

### 123 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### C3

Historical Incidence of Small Intestine Neoplasms in Control Male B6C3F1 Mice a



### Incidence in Controls

Duodenum Jejunum Duodenum, Jejunum, or Ileum

Study Adenoma Carcinoma Adenoma Carcinoma Adenoma Carcinoma Adenoma

or Carcinoma

Historical Incidence: Drinking Water Studies

Bromochloroacetic acid 3/50 1/50 0/50 1/50 3/50 2/50 5/50

Dibromoacetic acid 0/49 0/49 0/49 0/49 0/49 0/49 0/49

Dibromoacetonitrile 1/50 0/50 0/50 1/50 1/50 1/50 1/50

Dipropylene glycol 0/50 0/50 0/50 1/50 0/50 1/50 1/50

Sodium chlorate 1/50 0/50 0/50 2/50 1/50 2/50 3/50

Sodium dichromate dihydrate 1/50 0/50 0/50 0/50 1/50 0/50 1/50



### Overall Historical Incidence: Drinking Water Studies

Total (%) 6/299 (2.0%) 1/299 (0.3%) 0/299 5/299 (1.7%) 6/299 (2.0%) 6/299 (2.0%) 11/299 (3.7%)

Mean ± standard deviation 2.0% ± 2.2% 0.3% ± 0.8% 1.7% ± 1.5% 2.0% ± 2.2% 2.0% ± 1.8% 3.7% ± 3.7%

Range (0%-6%) (0%-2%) (0%-4%) (0%-6%) (0%-4%) (0%-10%)



### Overall Historical Incidence: All Routes

Total (%) 9/1,549 (0.6%) 3/1,549 (0.2%) 1/1,549 (0.1%) 25/1,549 (1.6%) 10/1,549 (0.6%) 30/1,549 (1.9%) 39/1,549 (2.5%)

Mean ± standard deviation 0.6% ± 1.3% 0.2% ± 0.8% 0.1% ± 0.4% 1.6% ± 2.2% 0.7% ± 1.3% 2.0% ± 2.2% 2.6% ± 2.7%

Range (0%-6%) (0%-4%) (0%-2%) (0%-8%) (0%-6%) (0%-8%) (0%-10%)

a Data as of March 2, 2007, with sodium dichromate dihydrate data added from Table C1

### Sodium Dichromate Dihydrate, NTP TR 546 124



### T ab le 

### C4

Summary of the Incidence of Nonneoplastic Lesions in Male Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate a



### 0 mg/L 14.3 mg/L 28.6 mg/L 85.7 mg/L 257.4 mg/L

Disposition Summary

Animals initially in study 50 50 50 50 50

Early deaths

Moribund 7 5 5 4 3

Natural deaths 10 10 10 8 15

Survivors

Died last week of study 1 1

Terminal sacrifice 32 35 35 38 31

Animals examined microscopically 50 50 50 50 50



### Alimentary System

Esophagus (50) (50) (50) (50) (50)

Gallbladder (47) (45) (44) (44) (39)

Intestine large, cecum (42) (44) (47) (46) (39)

Angiectasis 1 (2%)

Fibrosis 1 (2%)

Lymphoid tissue, hyperplasia 2 (4%)

Intestine large, colon (44) (45) (47) (46) (40)

Fibrosis 1 (2%)

Lymphangiectasis 1 (2%)

Lymphoid tissue, hyperplasia 1 (2%) 2 (4%) 2 (5%)

Intestine large, rectum (42) (47) (47) (46) (42)

Inflammation, suppurative 1 (2%)

Intestine small, duodenum (39) (43) (45) (48) (40)

Erosion 1 (2%)

Infiltration cellular, histiocyte 2 (5%) 4 (9%) 37 (77%) 35 (88%)

Infiltration cellular, mixed cell 1 (2%)

Epithelium, hyperplasia, focal 1 (2%) 2 (5%)

Epithelium, hyperplasia, diffuse 11 (26%) 18 (40%) 42 (88%) 32 (80%)

Intestine small, ileum (40) (42) (44) (45) (38)

Cyst 1 (2%)

Infiltration cellular, polymorphonuclear 1 (2%)

Inflammation, chronic active 1 (2%)

Epithelium, hyperplasia, diffuse 1 (2%)

Epithelium, inflammation, acute 1 (2%)

Goblet cell, hyperplasia 1 (2%)

Lymphoid tissue, hyperplasia 1 (2%) 2 (4%) 1 (3%)

Intestine small, jejunum (41) (42) (42) (46) (38)

Fibrosis 1 (2%)

Infiltration cellular, histiocyte 1 (2%)

Inflammation, suppurative 1 (2%)

Inflammation, chronic active 1 (2%)

Epithelium, hyperplasia, focal 1 (2%)

Epithelium, hyperplasia, diffuse 2 (4%) 1 (3%)

Lymphoid tissue, hyperplasia 2 (5%) 7 (17%) 5 (12%) 8 (17%) 3 (8%)

Liver (50) (50) (50) (50) (50)

Angiectasis 2 (4%)

Basophilic focus 3 (6%) 4 (8%) 1 (2%)

Basophilic focus, multiple 1 (2%) 1 (2%)

Clear cell focus 8 (16%) 9 (18%) 13 (26%) 11 (22%) 6 (12%)

Clear cell focus, multiple 12 (24%) 8 (16%) 6 (12%) 5 (10%) 1 (2%)

a Number of animals examined microscopically at the site and the number of animals with lesion

### 125 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### C4

Summary of the Incidence of Nonneoplastic Lesions in Male Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 28.6 mg/L 85.7 mg/L 257.4 mg/L

Alimentary System (continued)

Liver (continued) (50) (50) (50) (50) (50)

Congestion 1 (2%)

Cyst 1 (2%) 1 (2%) 2 (4%)

Eosinophilic focus 17 (34%) 16 (32%) 13 (26%) 16 (32%) 10 (20%)

Eosinophilic focus, multiple 10 (20%) 10 (20%) 6 (12%) 5 (10%) 2 (4%)

Fibrosis 2 (4%)

Hematopoietic cell proliferation 1 (2%)

Hemorrhage 1 (2%) 1 (2%) 1 (2%)

Hepatodiaphragmatic nodule 1 (2%) 2 (4%) 1 (2%)

Infarct 1 (2%)

Infiltration cellular, histiocyte 1 (2%) 3 (6%) 4 (8%) 4 (8%) 3 (6%)

Infiltration cellular, lymphocyte 1 (2%)

Inflammation, chronic 1 (2%) 1 (2%) 4 (8%) 2 (4%) 1 (2%)

Mixed cell focus 3 (6%) 1 (2%) 1 (2%) 3 (6%)

Mixed cell focus, multiple 1 (2%) 1 (2%)

Necrosis, focal 1 (2%) 3 (6%) 4 (8%) 5 (10%)

Bile duct, hyperplasia 1 (2%)

Centrilobular, necrosis 2 (4%) 1 (2%)

Hepatocyte, vacuolization cytoplasmic 5 (10%) 5 (10%) 1 (2%) 1 (2%) 3 (6%)

Mesentery (16) (10) (9) (16) (5)

Fibrosis 2 (22%) 1 (6%)

Inflammation, suppurative 1 (20%)

Inflammation, granulomatous 1 (6%)

Fat, necrosis 11 (69%) 7 (70%) 7 (78%) 12 (75%) 5 (100%)

Oral mucosa (50) (50) (50) (50) (50)

Pharyngeal, hyperplasia, squamous, focal 1 (2%)

Pancreas (49) (49) (50) (49) (48)

Atrophy 1 (2%) 1 (2%) 1 (2%) 1 (2%)

Cyst 1 (2%)

Fibrosis 1 (2%)

Acinus, cytoplasmic alteration 1 (2%) 1 (2%) 9 (18%) 8 (17%)

Salivary glands (49) (50) (49) (50) (50)

Atrophy 2 (4%)

Parotid gland, atrophy 1 (2%)

Submandibular gland, atrophy 1 (2%)

Stomach, forestomach (50) (50) (48) (50) (48)

Angiectasis 1 (2%)

Cyst 1 (2%)

Fibrosis 1 (2%)

Ulcer 3 (6%)

Epithelium, hyperplasia 4 (8%) 3 (6%) 3 (6%)

Stomach, glandular (50) (48) (48) (50) (47)

Atrophy, focal 2 (4%)

Cyst 1 (2%)

Erosion 1 (2%) 1 (2%) 1 (2%)

Erosion, focal 1 (2%)

Hyperplasia, focal 1 (2%) 1 (2%)

Infiltration cellular, polymorphonuclear 1 (2%)

Ulcer 1 (2%) 1 (2%)

Tongue (50) (50) (50) (50) (50)

Cyst 1 (2%) 1 (2%) 1 (2%)

Hyperplasia, squamous 1 (2%) 1 (2%) 1 (2%) 1 (2%)

Inflammation, chronic 5 (10%) 4 (8%) 4 (8%) 2 (4%)

Mineralization 1 (2%) 2 (4%) 1 (2%) 2 (4%)

### Sodium Dichromate Dihydrate, NTP TR 546 126



### T ab le 

### C4

Summary of the Incidence of Nonneoplastic Lesions in Male Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 28.6 mg/L 85.7 mg/L 257.4 mg/L

Alimentary System (continued)

Tongue (continued) (50) (50) (50) (50) (50)

Ulcer 1 (2%) 2 (4%)

Artery, inflammation, chronic 1 (2%) 1 (2%)

Tooth (1) (3) (2)

Malformation 1 (100%) 2 (67%) 2 (100%)



### Cardiovascular System

Blood vessel (2) (1) (1) (1) (1)

Heart (50) (50) (50) (50) (50)

Cardiomyopathy 45 (90%) 46 (92%) 43 (86%) 46 (92%) 36 (72%)

Inflammation, suppurative 1 (2%) 1 (2%)

Mineralization 1 (2%) 1 (2%)

Thrombosis 1 (2%) 1 (2%) 3 (6%)



### Endocrine System

Adrenal cortex (49) (49) (50) (50) (50)

Accessory adrenal cortical nodule 1 (2%)

Angiectasis 1 (2%) 1 (2%)

Degeneration, fatty 1 (2%)

Hyperplasia, focal 1 (2%) 2 (4%) 2 (4%)

Hypertrophy, focal 7 (14%) 12 (24%) 11 (22%) 13 (26%) 9 (18%)

Capsule, hemorrhage 1 (2%)

Capsule, hyperplasia 5 (10%) 13 (27%) 11 (22%) 12 (24%) 7 (14%)

Adrenal medulla (49) (48) (50) (50) (50)

Hyperplasia 1 (2%)

Islets, pancreatic (49) (49) (50) (50) (49)

Hyperplasia 39 (80%) 40 (82%) 34 (68%) 43 (86%) 20 (41%)

Parathyroid gland (46) (47) (45) (49) (47)

Cyst 1 (2%) 1 (2%)

Pituitary gland (49) (49) (48) (50) (47)

Pars distalis, cyst 2 (4%) 1 (2%) 2 (4%) 4 (8%) 1 (2%)

Pars distalis, hyperplasia, focal 1 (2%) 1 (2%) 2 (4%)

Thyroid gland (50) (50) (50) (50) (50)

Follicle, cyst 1 (2%) 2 (4%) 1 (2%) 3 (6%)

Follicle, degeneration, focal 3 (6%) 5 (10%) 4 (8%) 5 (10%) 1 (2%)

Follicular cell, hyperplasia, focal 1 (2%) 1 (2%) 1 (2%) 2 (4%)



### General Body System

None



### Genital System

Epididymis (50) (50) (50) (50) (50)

Degeneration 1 (2%)

Granuloma sperm 1 (2%) 2 (4%) 1 (2%)

Infiltration cellular, lymphocyte 1 (2%) 1 (2%) 1 (2%)

Inflammation, chronic 1 (2%)

### 127 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### C4

Summary of the Incidence of Nonneoplastic Lesions in Male Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 28.6 mg/L 85.7 mg/L 257.4 mg/L

Genital System (continued)

Preputial gland (50) (50) (50) (50) (50)

Atrophy 1 (2%)

Cyst 2 (4%) 1 (2%) 3 (6%) 4 (8%) 4 (8%)

Infiltration cellular, lymphocyte 1 (2%)

Inflammation, chronic 1 (2%)

Prostate (50) (49) (50) (50) (50)

Infiltration cellular, lymphocyte 2 (4%) 1 (2%)

Inflammation, suppurative 1 (2%) 1 (2%)

Inflammation, chronic 2 (4%) 1 (2%)

Seminal vesicle (50) (50) (50) (50) (50)

Fibrosis 1 (2%)

Inflammation, chronic 2 (4%) 1 (2%) 1 (2%)

Epithelium, hyperplasia 1 (2%)

Testes (50) (50) (50) (50) (50)

Germinal epithelium, atrophy 2 (4%) 3 (6%) 3 (6%) 2 (4%) 1 (2%)

Interstitial cell, hyperplasia 1 (2%)



### Hematopoietic System

Bone marrow (49) (50) (50) (50) (50)

Angiectasis 1 (2%)

Hyperplasia 5 (10%) 5 (10%) 1 (2%) 3 (6%)

Pigmentation 47 (96%) 50 (100%) 50 (100%) 50 (100%) 50 (100%)

Lymph node (8) (4) (6) (6) (5)

Bronchial, hyperplasia, lymphoid 1 (25%) 1 (17%)

Iliac, hemorrhage 1 (13%)

Iliac, hyperplasia, lymphoid 1 (13%) 1 (17%) 2 (33%)

Iliac, hyperplasia, plasma cell 1 (20%)

Iliac, pigmentation 4 (67%) 1 (20%)

Inguinal, hyperplasia, lymphoid 2 (25%) 1 (17%)

Inguinal, pigmentation 2 (50%) 1 (17%) 3 (60%)

Mediastinal, hemorrhage 1 (20%)

Mediastinal, hyperplasia, histiocytic 1 (17%)

Mediastinal, hyperplasia, lymphoid 1 (25%)

Popliteal, hyperplasia, lymphoid 1 (13%)

Renal, angiectasis 1 (13%)

Renal, hyperplasia, lymphoid 2 (25%) 1 (17%)

Renal, hyperplasia, plasma cell 1 (20%)

Lymph node, mandibular (47) (49) (49) (48) (46)

Hyperplasia, lymphoid 6 (13%) 6 (12%) 2 (4%) 4 (8%) 2 (4%)

Pigmentation 2 (4%)

Lymph node, mesenteric (47) (47) (49) (49) (46)

Ectasia 3 (6%)

Fibrosis 1 (2%)

Hemorrhage 1 (2%) 2 (4%)

Hyperplasia, lymphoid 4 (9%) 2 (4%) 3 (6%)

Infiltration cellular, histiocyte 14 (30%) 38 (81%) 31 (63%) 32 (65%) 42 (91%)

Inflammation, granulomatous 2 (4%) 1 (2%)

Necrosis, lymphoid 1 (2%)

Lymph node, pancreatic (5) (13) (10) (8) (16)

Hyperplasia, lymphoid 1 (13%) 1 (6%)

Infiltration cellular, histiocyte 2 (15%) 2 (20%) 5 (63%) 12 (75%)

### Sodium Dichromate Dihydrate, NTP TR 546 128



### T ab le 

### C4

Summary of the Incidence of Nonneoplastic Lesions in Male Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 28.6 mg/L 85.7 mg/L 257.4 mg/L

Hematopoietic System (continued)

Spleen (49) (48) (49) (49) (46)

Hematopoietic cell proliferation 17 (35%) 14 (29%) 13 (27%) 19 (39%) 25 (54%)

Hyperplasia, histiocytic 1 (2%)

Necrosis, lymphoid 1 (2%)

Lymphoid follicle, atrophy 1 (2%) 2 (4%) 1 (2%) 3 (7%)

Lymphoid follicle, hyperplasia 1 (2%) 6 (13%) 3 (6%) 5 (10%) 4 (9%)

Thymus (49) (50) (46) (49) (40)

Atrophy 2 (4%) 7 (14%) 2 (4%) 2 (4%) 1 (3%)

Hyperplasia, lymphoid 3 (6%) 3 (6%) 1 (2%) 2 (4%)

Necrosis, lymphoid 1 (2%)



### Integumentary System

Skin (50) (50) (50) (50) (50)

Congestion 1 (2%)

Cyst 1 (2%)

Cyst epithelial inclusion 2 (4%) 1 (2%) 1 (2%)

Edema 1 (2%) 1 (2%)

Hyperkeratosis 1 (2%)

Inflammation, granulomatous 1 (2%) 1 (2%)

Inflammation, chronic 2 (4%) 2 (4%) 1 (2%)

Ulcer 1 (2%) 3 (6%) 1 (2%)

Dermis, cyst 1 (2%)

Epidermis, hyperplasia 1 (2%) 1 (2%) 1 (2%)



### Musculoskeletal System

Bone (50) (50) (50) (50) (50)

Hyperostosis 1 (2%)

Cranium, osteopetrosis 1 (2%) 2 (4%) 1 (2%) 1 (2%)

Skeletal muscle (4) (2) (4) (1)

Fibrosis 2 (50%)

Hemorrhage 1 (25%)



### Nervous System

Brain (50) (50) (50) (50) (50)

Cyst epithelial inclusion 1 (2%)



### Respiratory System

Lung (50) (50) (50) (50) (50)

Congestion 1 (2%)

Infiltration cellular, histiocyte 1 (2%) 6 (12%) 3 (6%) 1 (2%)

Infiltration cellular, lymphocyte 1 (2%) 1 (2%)

Inflammation, granulomatous 1 (2%)

Inflammation, chronic 1 (2%)

Metaplasia, osseous 2 (4%)

Alveolar epithelium, hyperplasia 4 (8%) 3 (6%) 2 (4%) 5 (10%) 3 (6%)

Nose (50) (50) (50) (50) (50)

Glands, inflammation 1 (2%)

### 129 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### C4

Summary of the Incidence of Nonneoplastic Lesions in Male Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 28.6 mg/L 85.7 mg/L 257.4 mg/L

Special Senses System

Eye (48) (49) (49) (50) (47)

Atrophy 1 (2%) 1 (2%)

Harderian gland (50) (50) (49) (50) (50)

Hyperplasia, focal 1 (2%)



### Urinary System

Kidney (50) (50) (50) (50) (49)

Atrophy 1 (2%)

Cyst 3 (6%) 6 (12%) 4 (8%) 3 (6%) 2 (4%)

Fibrosis 1 (2%)

Hydronephrosis 1 (2%) 1 (2%) 1 (2%) 1 (2%)

Infarct 5 (10%) 1 (2%) 2 (4%) 6 (12%) 4 (8%)

Infiltration cellular, lymphocyte 1 (2%) 1 (2%) 1 (2%) 4 (8%)

Inflammation, suppurative 1 (2%) 1 (2%)

Metaplasia, osseous 1 (2%) 1 (2%) 1 (2%)

Mineralization 1 (2%)

Nephropathy 39 (78%) 43 (86%) 45 (90%) 45 (90%) 41 (84%)

Thrombosis 1 (2%)

Papilla, necrosis 1 (2%)

Renal tubule, atrophy 1 (2%)

Renal tubule, mineralization 1 (2%) 1 (2%)

Renal tubule, necrosis 1 (2%)

Renal tubule, pigmentation 7 (14%) 3 (6%) 3 (6%)

Urethra (1) (1) (1)

Angiectasis 1 (100%) 1 (100%)

Urinary bladder (49) (50) (50) (49) (46)

Fibrosis 1 (2%)

Infiltration cellular, lymphocyte 1 (2%) 1 (2%) 1 (2%)

### Sodium Dichromate Dihydrate, NTP TR 546 130

### 131



# APPENDIX D

SUMMARY OF LESIONS IN FEMALE MICE

IN THE 2-YEAR DRINKING WATER STUDY

OF SODIUM DICHROMATE DIHYDRATE

T ab le 

### D 1 Summary of the Incidence of Neoplasms in Female Mice

in the 2-Year Drinking Water Study of Sodium Dichromate Dihydrate

. . . . . . . . . . . . . . . 132

T ab le 

### D 2 Statistical Analysis of Primary Neoplasms in Female Mice

in the 2-Year Drinking Water Study of Sodium Dichromate Dihydrate

. . . . . . . . . . . . . . . 136

T ab le 

### D 3 Historical Incidence of Small Intestine Neoplasms

in Control Female B6C3F1 Mice

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140

T ab le 

### D 4 Summary of the Incidence of Nonneoplastic Lesions in Female Mice

in the 2-Year Drinking Water Study of Sodium Dichromate Dihydrate

. . . . . . . . . . . . . . . 141

### Sodium Dichromate Dihydrate, NTP TR 546 132



### T ab le 

### D 1

Summary of the Incidence of Neoplasms in Female Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate a



### 0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Disposition Summary

Animals initially in study 50 50 50 50 50

Early deaths

Moribund 5 2 2 3

Natural deaths 8 11 3 6 5

Survivors

Died last week of study 2 1 1 2

Terminal sacrifice 35 38 44 40 42

Animals examined microscopically 50 50 50 50 50



### Alimentary System

Gallbladder (44) (47) (48) (45) (50)

Sarcoma, metastatic, mesentery 1 (2%)

Intestine large, colon (43) (43) (48) (45) (48)

Intestine small, duodenum (42) (42) (48) (42) (48)

Adenoma 2 (4%) 12 (29%) 6 (13%)

Adenoma, multiple 1 (2%) 6 (13%)

Carcinoma 1 (2%) 6 (13%)

Intestine small, ileum (42) (43) (47) (44) (47)

Intestine small, jejunum (41) (42) (48) (44) (48)

Adenoma 1 (2%) 2 (5%) 4 (8%)

Adenoma, multiple 1 (2%)

Carcinoma 1 (2%) 2 (4%) 2 (5%) 1 (2%)

Sarcoma, metastatic, mesentery 1 (2%)

Liver (49) (50) (50) (50) (50)

Hemangioma 1 (2%)

Hemangiosarcoma 1 (2%) 3 (6%)

Hepatocellular adenoma 6 (12%) 11 (22%) 10 (20%) 5 (10%) 3 (6%)

Hepatocellular adenoma, multiple 8 (16%) 10 (20%) 3 (6%) 1 (2%)

Hepatocellular carcinoma 7 (14%) 9 (18%) 7 (14%) 6 (12%) 6 (12%)

Hepatocellular carcinoma, multiple 1 (2%) 1 (2%) 1 (2%)

Mesentery (20) (23) (23) (23) (9)

Carcinoma, metastatic, Harderian gland 1 (4%)

Fibrosarcoma 3 (15%)

Fibrosarcoma, metastatic, skin 1 (4%) 1 (11%)

Granulosa-theca tumor malignant, metastatic,

ovary 1 (4%)

Hemangiosarcoma, metastatic, spleen 1 (5%)

Liposarcoma, metastatic, skin 1 (4%)

Sarcoma 2 (9%) 2 (9%)

Sarcoma, metastatic, skin 1 (4%)

Pancreas (48) (50) (49) (50) (50)

Fibrosarcoma, metastatic, skin 1 (2%)

Hepatocellular carcinoma, metastatic, liver 1 (2%)

Sarcoma, metastatic, mesentery 1 (2%)

Salivary glands (50) (50) (50) (48) (49)

Fibrosarcoma, metastatic, skin 1 (2%)

Stomach, forestomach (49) (49) (50) (48) (50)

Squamous cell papilloma 1 (2%) 2 (4%) 3 (6%)

Stomach, glandular (49) (48) (50) (48) (50)

Sarcoma, metastatic, mesentery 1 (2%)

Tongue (50) (50) (49) (48) (50)

### 133 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### D 1

Summary of the Incidence of Neoplasms in Female Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Cardiovascular System

Heart (50) (50) (50) (50) (50)

Granulosa-theca tumor malignant, metastatic,

ovary 1 (2%)

Sarcoma, metastatic, mesentery 1 (2%)



### Endocrine System

Adrenal cortex (49) (50) (50) (50) (50)

Sarcoma, metastatic, mesentery 1 (2%)

Capsule, adenoma 1 (2%)

Capsule, carcinoma 1 (2%)

Adrenal medulla (49) (50) (50) (50) (50)

Pheochromocytoma benign 1 (2%) 2 (4%) 1 (2%)

Islets, pancreatic (49) (50) (50) (50) (50)

Adenoma 1 (2%)

Carcinoma 1 (2%)

Parathyroid gland (48) (49) (50) (44) (49)

Pituitary gland (48) (48) (48) (48) (49)

Pars distalis, adenoma 3 (6%) 3 (6%) 2 (4%) 3 (6%) 3 (6%)

Thyroid gland (50) (50) (50) (49) (50)

Adenoma 1 (2%)

Fibrosarcoma, metastatic, skin 1 (2%)

C-cell, carcinoma 1 (2%)

Follicular cell, adenoma 1 (2%) 1 (2%) 2 (4%)

Follicular cell, carcinoma 1 (2%)



### General Body System

Tissue NOS (1)



### Genital System

Clitoral gland (50) (50) (50) (50) (48)

Sarcoma, metastatic, skin 1 (2%) 1 (2%)

Ovary (50) (49) (47) (48) (49)

Cystadenoma 1 (2%) 3 (6%) 3 (6%) 2 (4%) 2 (4%)

Granulosa cell tumor benign 1 (2%)

Granulosa-theca tumor malignant 1 (2%)

Hemangioma 1 (2%)

Hemangiosarcoma 1 (2%) 1 (2%)

Teratoma benign 1 (2%)

Uterus (50) (50) (50) (50) (50)

Hemangiosarcoma 2 (4%)

Polyp stromal 1 (2%)

Sarcoma stromal 1 (2%)

Vagina (1)

Squamous cell papilloma 1 (100%)

### Sodium Dichromate Dihydrate, NTP TR 546 134



### T ab le 

### D 1

Summary of the Incidence of Neoplasms in Female Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Hematopoietic System

Bone marrow (50) (50) (50) (50) (50)

Lymph node (10) (7) (6) (5) (6)

Axillary, sarcoma, metastatic, skin 1 (17%)

Bronchial, liposarcoma, metastatic, skin 1 (14%)

Inguinal, sarcoma, metastatic, skin 1 (17%)

Mediastinal, fibrosarcoma, metastatic, skin 1 (14%)

Mediastinal, granulosa-theca tumor malignant,

metastatic, ovary 1 (14%)

Mediastinal, liposarcoma, metastatic, skin 1 (14%)

Mediastinal, sarcoma, metastatic, skin 1 (17%)

Lymph node, mandibular (50) (48) (49) (48) (48)

Carcinoma, metastatic, Harderian gland 1 (2%)

Fibrosarcoma, metastatic, skin 1 (2%)

Lymph node, mesenteric (46) (48) (46) (50) (50)

Fibrosarcoma, metastatic, mesentery 1 (2%)

Sarcoma, metastatic, mesentery 1 (2%)

Lymph node, pancreatic (14) (12) (15) (14) (13)

Granulosa cell tumor malignant, metastatic,

ovary 1 (8%)

Spleen (48) (48) (50) (50) (50)

Hemangiosarcoma 1 (2%) 1 (2%) 1 (2%) 1 (2%)

Sarcoma, metastatic, mesentery 1 (2%)

Sarcoma, metastatic, skin 1 (2%)

Thymus (46) (38) (43) (40) (47)



### Integumentary System

Mammary gland (50) (48) (50) (50) (50)

Carcinoma 1 (2%)

Fibroadenoma 1 (2%)

Skin (50) (50) (50) (49) (50)

Fibrosarcoma 1 (2%)

Hemangioma 1 (2%)

Squamous cell papilloma 1 (2%)

Pinna, fibrosarcoma 1 (2%)

Subcutaneous tissue, fibrosarcoma 1 (2%) 1 (2%) 1 (2%) 2 (4%)

Subcutaneous tissue, liposarcoma 1 (2%)

Subcutaneous tissue, sarcoma 1 (2%) 1 (2%) 1 (2%) 1 (2%) 1 (2%)



### Musculoskeletal System

Bone (50) (50) (50) (50) (50)

Osteoma 1 (2%)

Osteosarcoma 1 (2%)

Cranium, osteoma 1 (2%)

Skeletal muscle (2) (6) (1) (1) (1)

Carcinoma, metastatic, Harderian gland 1 (100%)

Fibrosarcoma, metastatic, skin 1 (50%) 1 (17%)

Granulosa-theca tumor malignant, metastatic,

ovary 1 (17%)

Liposarcoma, metastatic, skin 1 (17%)

Sarcoma 1 (17%)

Sarcoma, metastatic, mesentery 1 (17%)

### 135 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### D 1

Summary of the Incidence of Neoplasms in Female Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Nervous System

Brain (50) (50) (50) (50) (50)



### Respiratory System

Lung (50) (50) (50) (50) (50)

Alveolar/bronchiolar adenoma 1 (2%) 5 (10%) 7 (14%) 2 (4%) 2 (4%)

Alveolar/bronchiolar carcinoma 2 (4%) 2 (4%) 2 (4%) 1 (2%)

Carcinoma, metastatic, Harderian gland 1 (2%)

Fibrosarcoma, metastatic, skin 2 (4%)

Granulosa-theca tumor malignant, metastatic,

ovary 1 (2%)

Hepatocellular carcinoma, metastatic, liver 2 (4%) 1 (2%) 1 (2%)

Liposarcoma, metastatic, skin 1 (2%)

Sarcoma, metastatic, skin 1 (2%)

Nose (50) (50) (50) (50) (50)

Carcinoma, metastatic, Harderian gland 1 (2%)



### Special Senses System

Eye (49) (48) (48) (46) (50)

Harderian gland (49) (49) (50) (50) (50)

Adenoma 4 (8%) 5 (10%) 5 (10%) 7 (14%) 5 (10%)

Carcinoma 1 (2%) 1 (2%) 1 (2%)



### Urinary System

Kidney (50) (49) (50) (49) (50)

Ureter (1)

Urinary bladder (50) (48) (50) (48) (49)



### Systemic Lesions

Multiple organs b (50) (50) (50) (50) (50)

Histiocytic sarcoma 2 (4%) 1 (2%) 1 (2%) 1 (2%)

Lymphoma malignant 7 (14%) 3 (6%) 2 (4%) 5 (10%) 5 (10%)



### Neoplasm Summary

Total animals with primary neoplasms c 36 37 37 39 38

Total primary neoplasms 58 71 62 61 65

Total animals with benign neoplasms 27 28 27 25 29

Total benign neoplasms 30 43 40 37 38

Total animals with malignant neoplasms 22 23 19 21 18

Total malignant neoplasms 28 28 22 24 27

Total animals with metastatic neoplasms 5 6 3 1 3

Total metastatic neoplasms 5 29 13 1 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

### Sodium Dichromate Dihydrate, NTP TR 546 136



### T ab le 

### D 2

Statistical Analysis of Primary Neoplasms in Female Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Harderian Gland: Adenoma

Overall rate a 4/50 (8%) 5/50 (10%) 5/50 (10%) 7/50 (14%) 5/50 (10%)

Adjusted rate b 8.9% 10.8% 10.4% 15.0% 10.6%

Terminal rate c 4/37 (11%) 4/39 (10%) 5/45 (11%) 7/42 (17%) 5/42 (12%)

First incidence (days) 729 (T) 671 729 (T) 729 (T) 729 (T)

Poly-3 test d P=0.516 P=0.517 P=0.538 P=0.283 P=0.531



### Harderian Gland: Adenoma or Carcinoma

Overall rate 5/50 (10%) 5/50 (10%) 6/50 (12%) 7/50 (14%) 6/50 (12%)

Adjusted rate 11.0% 10.8% 12.4% 15.0% 12.7%

Terminal rate 4/37 (11%) 4/39 (10%) 5/45 (11%) 7/42 (17%) 6/42 (14%)

First incidence (days) 583 671 611 729 (T) 729 (T)

Poly-3 test P=0.462 P=0.620N P=0.541 P=0.398 P=0.527



### Small Intestine (Duodenum): Adenoma

Overall rate 0/50 (0%) 0/50 (0%) 2/50 (4%) 13/50 (26%) 12/50 (24%)

Adjusted rate 0.0% 0.0% 4.2% 27.8% 25.2%

Terminal rate 0/37 (0%) 0/39 (0%) 2/45 (4%) 13/42 (31%) 11/42 (26%)

First incidence (days)

— e

— 729 (T) 729 (T) 693

Poly-3 test P<0.001

— f P=0.251 P<0.001 P<0.001



### Small Intestine (Duodenum): Carcinoma

Overall rate 0/50 (0%) 0/50 (0%) 0/50 (0%) 1/50 (2%) 6/50 (12%)

Adjusted rate 0.0% 0.0% 0.0% 2.1% 12.6%

Terminal rate 0/37 (0%) 0/39 (0%) 0/45 (0%) 1/42 (2%) 5/42 (12%)

First incidence (days)

— — — 729 (T) 625

Poly-3 test P<0.001

— — P=0.507 P=0.019



### Small Intestine (Jejunum): Adenoma

Overall rate 0/50 (0%) 1/50 (2%) 0/50 (0%) 2/50 (4%) 5/50 (10%)

Adjusted rate 0.0% 2.2% 0.0% 4.3% 10.6%

Terminal rate 0/37 (0%) 1/39 (3%) 0/45 (0%) 2/42 (5%) 5/42 (12%)

First incidence (days)

— 729 (T)

— 729 (T) 729 (T)

Poly-3 test P=0.002 P=0.504

— P=0.246 P=0.035



### Small Intestine (Duodenum, Jejunum, or Ileum): Adenoma

Overall rate 0/50 (0%) 1/50 (2%) 2/50 (4%) 15/50 (30%) 16/50 (32%)

Adjusted rate 0.0% 2.2% 4.2% 32.0% 33.7%

Terminal rate 0/37 (0%) 1/39 (3%) 2/45 (4%) 15/42 (36%) 15/42 (36%)

First incidence (days)

— 729 (T) 729 (T) 729 (T) 693

Poly-3 test P<0.001 P=0.504 P=0.251 P<0.001 P<0.001



### Small Intestine (Duodenum, Jejunum, or Ileum): Carcinoma

Overall rate 1/50 (2%) 0/50 (0%) 2/50 (4%) 3/50 (6%) 7/50 (14%)

Adjusted rate 2.2% 0.0% 4.2% 6.4% 14.7%

Terminal rate 1/37 (3%) 0/39 (0%) 2/45 (4%) 3/42 (7%) 6/42 (14%)

First incidence (days) 729 (T)

— 729 (T) 729 (T) 625

Poly-3 test P<0.001 P=0.496N P=0.521 P=0.319 P=0.037

### 137 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### D 2

Statistical Analysis of Primary Neoplasms in Female Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Small Intestine (Duodenum, Jejunum, or Ileum): Adenoma or Carcinoma

Overall rate 1/50 (2%) 1/50 (2%) 4/50 (8%) 17/50 (34%) 22/50 (44%)

Adjusted rate 2.2% 2.2% 8.3% 36.3% 45.9%

Terminal rate 1/37 (3%) 1/39 (3%) 4/45 (9%) 17/42 (41%) 20/42 (48%)

First incidence (days) 729 (T) 729 (T) 729 (T) 729 (T) 625

Poly-3 test P<0.001 P=0.756N P=0.198 P<0.001 P<0.001



### Liver: Hemangiosarcoma

Overall rate 1/49 (2%) 3/50 (6%) 0/50 (0%) 0/50 (0%) 0/50 (0%)

Adjusted rate 2.2% 6.5% 0.0% 0.0% 0.0%

Terminal rate 0/37 (0%) 2/39 (5%) 0/45 (0%) 0/42 (0%) 0/42 (0%)

First incidence (days) 668 688

— — — Poly-3 test P=0.149N P=0.313 P=0.489N P=0.494N P=0.491N



### Liver: Hepatocellular Adenoma

Overall rate 14/49 (29%) 21/50 (42%) 13/50 (26%) 6/50 (12%) 3/50 (6%)

Adjusted rate 31.0% 45.5% 27.1% 12.8% 6.3%

Terminal rate 13/37 (35%) 21/39 (54%) 13/45 (29%) 6/42 (14%) 3/42 (7%)

First incidence (days) 696 729 (T) 729 (T) 729 (T) 729 (T)

Poly-3 test P<0.001N P=0.109 P=0.429N P=0.029N P=0.002N



### Liver: Hepatocellular Carcinoma

Overall rate 8/49 (16%) 10/50 (20%) 7/50 (14%) 6/50 (12%) 7/50 (14%)

Adjusted rate 17.7% 21.3% 14.6% 12.7% 14.6%

Terminal rate 7/37 (19%) 7/39 (18%) 7/45 (16%) 5/42 (12%) 4/42 (10%)

First incidence (days) 696 629 729 (T) 555 664

Poly-3 test P=0.327N P=0.432 P=0.451N P=0.351N P=0.452N



### Liver: Hepatocellular Adenoma or Carcinoma

Overall rate 17/49 (35%) 25/50 (50%) 17/50 (34%) 10/50 (20%) 10/50 (20%)

Adjusted rate 37.6% 53.2% 35.5% 21.1% 20.9%

Terminal rate 16/37 (43%) 22/39 (56%) 17/45 (38%) 9/42 (21%) 7/42 (17%)

First incidence (days) 696 629 729 (T) 555 664

Poly-3 test P=0.003N P=0.094 P=0.501N P=0.062N P=0.058N



### Lung: Alveolar/bronchiolar Adenoma

Overall rate 1/50 (2%) 5/50 (10%) 7/50 (14%) 2/50 (4%) 2/50 (4%)

Adjusted rate 2.2% 10.8% 14.6% 4.3% 4.2%

Terminal rate 1/37 (3%) 5/39 (13%) 6/45 (13%) 2/42 (5%) 1/42 (2%)

First incidence (days) 729 (T) 729 (T) 722 729 (T) 625

Poly-3 test P=0.205N P=0.106 P=0.037 P=0.513 P=0.520



### Lung: Alveolar/bronchiolar Adenoma or Carcinoma

Overall rate 2/50 (4%) 7/50 (14%) 9/50 (18%) 3/50 (6%) 2/50 (4%)

Adjusted rate 4.4% 15.2% 18.8% 6.4% 4.2%

Terminal rate 2/37 (5%) 7/39 (18%) 8/45 (18%) 2/42 (5%) 1/42 (2%)

First incidence (days) 729 (T) 729 (T) 722 599 625

Poly-3 test P=0.075N P=0.084 P=0.032 P=0.521 P=0.673N

### Sodium Dichromate Dihydrate, NTP TR 546 138



### T ab le 

### D 2

Statistical Analysis of Primary Neoplasms in Female Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Mesentery: Fibrosarcoma

Overall rate 3/50 (6%) 0/50 (0%) 0/50 (0%) 0/50 (0%) 0/50 (0%)

Adjusted rate 6.6% 0.0% 0.0% 0.0% 0.0%

Terminal rate 2/37 (5%) 0/39 (0%) 0/45 (0%) 0/42 (0%) 0/42 (0%)

First incidence (days) 655

— — — — Poly-3 test P=0.197N P=0.116N P=0.109N P=0.113N P=0.111N



### Ovary: Cystadenoma

Overall rate 1/50 (2%) 3/49 (6%) 3/47 (6%) 2/48 (4%) 2/49 (4%)

Adjusted rate 2.2% 6.7% 6.7% 4.4% 4.3%

Terminal rate 0/37 (0%) 3/38 (8%) 3/42 (7%) 2/41 (5%) 2/41 (5%)

First incidence (days) 695 729 (T) 729 (T) 729 (T) 729 (T)

Poly-3 test P=0.541N P=0.304 P=0.303 P=0.500 P=0.509



### Pituitary Gland (Pars Distalis): Adenoma

Overall rate 3/48 (6%) 3/48 (6%) 2/48 (4%) 3/48 (6%) 3/49 (6%)

Adjusted rate 6.7% 6.8% 4.3% 6.7% 6.5%

Terminal rate 1/37 (3%) 3/37 (8%) 2/44 (5%) 3/41 (7%) 3/41 (7%)

First incidence (days) 552 729 (T) 729 (T) 729 (T) 729 (T)

Poly-3 test P=0.559 P=0.652 P=0.488N P=0.659 P=0.649N



### Skin: Fibrosarcoma or Sarcoma

Overall rate 2/50 (4%) 3/50 (6%) 2/50 (4%) 2/50 (4%) 3/50 (6%)

Adjusted rate 4.4% 6.4% 4.2% 4.2% 6.3%

Terminal rate 1/37 (3%) 2/39 (5%) 2/45 (4%) 1/42 (2%) 1/42 (2%)

First incidence (days) 695 461 729 (T) 646 646

Poly-3 test P=0.484 P=0.516 P=0.673N P=0.679N P=0.526



### Stomach (Forestomach): Squamous Cell Papilloma

Overall rate 1/50 (2%) 2/50 (4%) 0/50 (0%) 0/50 (0%) 3/50 (6%)

Adjusted rate 2.2% 4.3% 0.0% 0.0% 6.3%

Terminal rate 0/37 (0%) 2/39 (5%) 0/45 (0%) 0/42 (0%) 3/42 (7%)

First incidence (days) 616 729 (T)

— — 729 (T)

Poly-3 test P=0.145 P=0.505 P=0.490N P=0.494N P=0.320



### All Organs: Hemangiosarcoma

Overall rate 2/50 (4%) 3/50 (6%) 2/50 (4%) 4/50 (8%) 0/50 (0%)

Adjusted rate 4.4% 6.5% 4.2% 8.5% 0.0%

Terminal rate 0/37 (0%) 2/39 (5%) 2/45 (4%) 3/42 (7%) 0/42 (0%)

First incidence (days) 583 688 729 (T) 646

— Poly-3 test P=0.140N P=0.505 P=0.677N P=0.350 P=0.230N



### All Organs: Hemangioma or Hemangiosarcoma

Overall rate 3/50 (6%) 3/50 (6%) 4/50 (8%) 4/50 (8%) 0/50 (0%)

Adjusted rate 6.6% 6.5% 8.3% 8.5% 0.0%

Terminal rate 1/37 (3%) 2/39 (5%) 4/45 (9%) 3/42 (7%) 0/42 (0%)

First incidence (days) 583 688 729 (T) 646

— Poly-3 test P=0.072N P=0.658N P=0.524 P=0.515 P=0.113N

### 139 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### D 2

Statistical Analysis of Primary Neoplasms in Female Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

All Organs: Malignant Lymphoma

Overall rate 7/50 (14%) 3/50 (6%) 2/50 (4%) 5/50 (10%) 5/50 (10%)

Adjusted rate 15.3% 6.4% 4.2% 10.4% 10.5%

Terminal rate 4/37 (11%) 1/39 (3%) 2/45 (4%) 2/42 (5%) 4/42 (10%)

First incidence (days) 616 632 729 (T) 428 652

Poly-3 test P=0.472 P=0.149N P=0.068N P=0.346N P=0.351N



### All Organs: Benign Neoplasms

Overall rate 27/50 (54%) 28/50 (56%) 27/50 (54%) 25/50 (50%) 29/50 (58%)

Adjusted rate 56.6% 60.4% 55.9% 53.4% 59.3%

Terminal rate 21/37 (57%) 26/39 (67%) 25/45 (56%) 25/42 (60%) 26/42 (62%)

First incidence (days) 212 671 646 729 (T) 170

Poly-3 test P=0.479 P=0.434 P=0.555N P=0.457N P=0.475



### All Organs: Malignant Neoplasms

Overall rate 22/50 (44%) 23/50 (46%) 19/50 (38%) 21/50 (42%) 18/50 (36%)

Adjusted rate 46.7% 47.1% 38.2% 42.5% 36.8%

Terminal rate 15/37 (41%) 14/39 (36%) 15/45 (33%) 14/42 (33%) 12/42 (29%)

First incidence (days) 583 461 311 428 625

Poly-3 test P=0.202N P=0.564 P=0.262N P=0.417N P=0.220N



### All Organs: Benign or Malignant Neoplasms

Overall rate 36/50 (72%) 37/50 (74%) 37/50 (74%) 39/50 (78%) 38/50 (76%)

Adjusted rate 73.4% 75.8% 74.0% 79.0% 76.2%

Terminal rate 26/37 (70%) 28/39 (72%) 32/45 (71%) 32/42 (76%) 31/42 (74%)

First incidence (days) 212 461 311 428 170

Poly-3 test P=0.441 P=0.484 P=0.566 P=0.342 P=0.465

(T) Terminal sacrifice

a Number of neoplasm-bearing animals/number of animals examined. Denominator is number of animals examined microscopically for liver, lung, ovary,

and pituitary gland; for other tissues, denominator is number of animals necropsied.

b Poly-3 estimated neoplasm incidence after adjustment for intercurrent mortality

c Observed incidence at terminal kill

d Beneath the control incidence is the P value 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 Poly-3 test accounts for the differential mortality in animals that do not reach terminal

sacrifice. A negative trend or a lower incidence in an exposed group is indicated by N

. e Not applicable; no neoplasms in animal group

f Value of statistic cannot be computed.

### Sodium Dichromate Dihydrate, NTP TR 546 140



### T ab le 

### D 3

Historical Incidence of Small Intestine Neoplasms in Control Female B6C3F1 Mice a



### Incidence in Controls

Duodenum Jejunum Duodenum, Jejunum, or Ileum

Study Adenoma Carcinoma Adenoma Carcinoma Adenoma Carcinoma Adenoma

or Carcinoma

Historical Incidence: Drinking Water Studies

Bromochloroacetic acid 1/50 0/50 0/50 1/50 1/50 1/50 2/50

Bromodichloromethane 0/50 0/50 0/50 0/50 0/50 1/50 1/50

Dibromoacetic acid 0/50 0/50 0/50 0/50 0/50 0/50 0/50

Dibromoacetonitrile 0/50 0/50 0/50 0/50 0/50 0/50 0/50

Dipropylene glycol 0/50 0/50 0/50 0/50 0/50 0/50 0/50

Sodium chlorate 0/50 0/50 0/50 0/50 0/50 0/50 0/50

Sodium dichromate dihydrate 0/50 0/50 0/50 1/50 0/50 1/50 1/50



### Overall Historical Incidence: Drinking Water Studies

Total (%) 1/350 (0.3%) 0/350 0/350 2/350 (0.6%) 1/350 (0.3%) 3/350 (0.9%) 4/350 (1.1%)

Mean ± standard deviation 0.3% ± 0.8% 0.6% ± 1.0% 0.3% ± 0.8% 0.9% ± 1.1% 1.1% ± 1.6%

Range (0%-2%) (0%-2%) (0%-2%) (0%-2%) (0%-4%)



### Overall Historical Incidence: All Routes

Total (%) 3/1,648 (0.2%) 1/1,648 (0.1%) 0/1,648 5/1,648 (0.3%) 3/1,648 (0.2%) 8/1,648 (0.5%) 11/1,648 (0.7%)

Mean ± standard deviation 0.2% ± 0.6% 0.1% ± 0.4% 0.3% ± 0.7% 0.2% ± 0.6% 0.5% ± 0.8% 0.7% ± 1.1%

Range (0%-2%) (0%-2%) (0%-2%) (0%-2%) (0%-2%) (0%-4%)

a Data as of March 2, 2007, with sodium dichromate dihydrate data added from Table D1

### T ab le 

### D 4

Summary of the Incidence of Nonneoplastic Lesions in Female Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate a



### 0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Disposition Summary

Animals initially in study 50 50 50 50 50

Early deaths

Moribund 5 2 2 3

Natural deaths 8 11 3 6 5

Survivors

Died last week of study 2 1 1 2

Terminal sacrifice 35 38 44 40 42

Animals examined microscopically 50 50 50 50 50



### Alimentary System

Gallbladder (44) (47) (48) (45) (50)

Intestine large, colon (43) (43) (48) (45) (48)

Edema 1 (2%)

Lymphoid tissue, hyperplasia 2 (5%) 3 (7%) 1 (2%) 1 (2%) 2 (4%)

Intestine small, duodenum (42) (42) (48) (42) (48)

Cyst 1 (2%)

Dilatation 1 (2%)

Hyperplasia, lymphoid 1 (2%)

Infiltration cellular, histiocyte 4 (8%) 33 (79%) 40 (83%)

Epithelium, hyperplasia, focal 1 (2%) 2 (5%)

Epithelium, hyperplasia, diffuse 16 (38%) 35 (73%) 31 (74%) 42 (88%)

Lymphoid tissue, hyperplasia 1 (2%) 1 (2%) 2 (4%)

Intestine small, ileum (42) (43) (47) (44) (47)

Inflammation, suppurative 1 (2%)

Intestine small, jejunum (41) (42) (48) (44) (48)

Fibrosis 1 (2%)

Infiltration cellular, histiocyte 2 (5%) 8 (17%)

Inflammation, suppurative 4 (10%) 1 (2%) 1 (2%)

Epithelium, hyperplasia, focal 1 (2%) 1 (2%)

Epithelium, hyperplasia, diffuse 2 (5%) 1 (2%) 8 (17%)

Lymphoid tissue, hyperplasia 6 (15%) 6 (14%) 6 (13%) 4 (9%) 3 (6%)

Liver (49) (50) (50) (50) (50)

Basophilic focus 3 (6%) 4 (8%) 2 (4%) 1 (2%)

Basophilic focus, multiple 2 (4%)

Clear cell focus 3 (6%) 5 (10%) 2 (4%) 1 (2%)

Cyst 1 (2%) 1 (2%)

Cyst, multiple 1 (2%)

Eosinophilic focus 11 (22%) 13 (26%) 5 (10%) 4 (8%) 4 (8%)

Eosinophilic focus, multiple 3 (6%) 5 (10%) 3 (6%) 1 (2%)

Hematopoietic cell proliferation 3 (6%) 1 (2%) 1 (2%)

Hemorrhage 1 (2%) 2 (4%)

Infiltration cellular, histiocyte 2 (4%) 15 (30%) 23 (46%) 32 (64%) 45 (90%)

Infiltration cellular, lymphocyte 2 (4%) 1 (2%) 2 (4%)

Inflammation, chronic 16 (33%) 21 (42%) 22 (44%) 27 (54%) 24 (48%)

Mixed cell focus 2 (4%) 4 (8%) 1 (2%) 1 (2%)

Necrosis, focal 1 (2%) 1 (2%) 2 (4%) 1 (2%)

Tension lipidosis 1 (2%) 1 (2%)

Thrombosis 1 (2%)

Hepatocyte, vacuolization cytoplasmic 4 (8%) 5 (10%) 5 (10%) 2 (4%)

a Number of animals examined microscopically at the site and the number of animals with lesion 

### 141 Sodium Dichromate Dihydrate, NTP TR 546

### Sodium Dichromate Dihydrate, NTP TR 546 142



### T ab le 

### D 4

Summary of the Incidence of Nonneoplastic Lesions in Female Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Alimentary System (continued)

Mesentery (20) (23) (23) (23) (9)

Fibrosis 1 (4%)

Hemorrhage 1 (11%)

Inflammation, granulomatous 1 (4%)

Inflammation, chronic 1 (4%) 1 (11%)

Fat, hemorrhage 1 (4%)

Fat, necrosis 16 (80%) 20 (87%) 20 (87%) 21 (91%) 6 (67%)

Pancreas (48) (50) (49) (50) (50)

Atrophy 1 (2%) 1 (2%) 2 (4%)

Cyst 1 (2%) 1 (2%)

Necrosis 1 (2%)

Acinus, atrophy 2 (4%)

Acinus, cytoplasmic alteration 6 (12%) 6 (12%) 14 (28%) 32 (64%)

Acinus, hyperplasia, focal 1 (2%)

Salivary glands (50) (50) (50) (48) (49)

Atrophy 1 (2%)

Fibrosis 1 (2%)

Infiltration cellular, lymphocyte 1 (2%) 1 (2%)

Inflammation, chronic 2 (4%)

Submandibular gland, atrophy 1 (2%)

Stomach, forestomach (49) (49) (50) (48) (50)

Cyst 2 (4%)

Diverticulum 1 (2%)

Edema 1 (2%) 1 (2%)

Erosion 1 (2%)

Infiltration cellular, lymphocyte 1 (2%)

Inflammation, chronic 1 (2%)

Mineralization 2 (4%)

Ulcer 3 (6%) 1 (2%) 1 (2%) 2 (4%)

Epithelium, hyperplasia 2 (4%) 2 (4%) 2 (4%) 3 (6%)

Stomach, glandular (49) (48) (50) (48) (50)

Cyst 1 (2%) 1 (2%)

Degeneration, cystic 1 (2%)

Erosion 2 (4%) 1 (2%)

Fibrosis 1 (2%)

Infiltration cellular, mixed cell 1 (2%)

Inflammation, suppurative 1 (2%)

Ulcer 1 (2%)

Glands, hyperplasia 1 (2%)

Tongue (50) (50) (49) (48) (50)

Inflammation, chronic 7 (14%) 6 (12%) 3 (6%) 5 (10%) 5 (10%)

Mineralization 1 (2%) 1 (2%) 2 (4%)

Artery, inflammation, chronic 1 (2%) 3 (6%)



### Cardiovascular System

Heart (50) (50) (50) (50) (50)

Cardiomyopathy 40 (80%) 34 (68%) 43 (86%) 42 (84%) 43 (86%)

Mineralization 1 (2%)

Artery, inflammation, chronic 1 (2%)

### 143 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### D 4

Summary of the Incidence of Nonneoplastic Lesions in Female Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Endocrine System

Adrenal cortex (49) (50) (50) (50) (50)

Accessory adrenal cortical nodule 3 (6%) 1 (2%) 1 (2%) 3 (6%)

Hematopoietic cell proliferation 1 (2%) 1 (2%)

Hyperplasia, focal 1 (2%) 1 (2%) 1 (2%)

Hyperplasia, diffuse 1 (2%) 1 (2%)

Hypertrophy, focal 2 (4%) 1 (2%) 1 (2%)

Vacuolization cytoplasmic 1 (2%) 1 (2%)

Capsule, hyperplasia 10 (20%) 4 (8%) 6 (12%) 9 (18%) 14 (28%)

Adrenal medulla (49) (50) (50) (50) (50)

Hyperplasia 1 (2%) 1 (2%) 1 (2%)

Islets, pancreatic (49) (50) (50) (50) (50)

Hyperplasia 10 (20%) 5 (10%) 3 (6%) 5 (10%) 7 (14%)

Parathyroid gland (48) (49) (50) (44) (49)

Cyst 1 (2%) 1 (2%)

Pituitary gland (48) (48) (48) (48) (49)

Pars distalis, angiectasis 1 (2%)

Pars distalis, cyst 1 (2%)

Pars distalis, hyperplasia, focal 5 (10%) 3 (6%) 3 (6%) 2 (4%) 1 (2%)

Pars intermedia, fibrosis 1 (2%)

Rathke’s cleft, cyst 1 (2%) 1 (2%)

Thyroid gland (50) (50) (50) (49) (50)

Infiltration cellular, lymphocyte 1 (2%) 1 (2%)

Infiltration cellular, mixed cell 1 (2%) 2 (4%)

Inflammation, suppurative, focal 1 (2%)

Inflammation, chronic 1 (2%)

Follicle, cyst 2 (4%) 1 (2%) 3 (6%) 2 (4%) 2 (4%)

Follicle, degeneration, focal 12 (24%) 11 (22%) 14 (28%) 10 (20%) 11 (22%)

Follicular cell, hyperplasia 1 (2%)

Follicular cell, hyperplasia, focal 1 (2%) 1 (2%) 2 (4%)

Follicular cell, hypertrophy 1 (2%)



### General Body System

Tissue NOS (1)



### Genital System

Clitoral gland (50) (50) (50) (50) (48)

Cyst 1 (2%) 1 (2%) 1 (2%)

Inflammation, chronic 1 (2%)

Ovary (50) (49) (47) (48) (49)

Angiectasis 1 (2%) 1 (2%) 1 (2%) 2 (4%)

Atrophy 1 (2%) 2 (4%)

Cyst 10 (20%) 13 (27%) 12 (26%) 11 (23%) 10 (20%)

Hematocyst 1 (2%)

Hemorrhage 1 (2%) 9 (18%) 2 (4%) 4 (8%) 3 (6%)

Hyperplasia 1 (2%)

Infiltration cellular, lymphocyte 1 (2%)

Mineralization 1 (2%)

Thrombosis 1 (2%)

### Sodium Dichromate Dihydrate, NTP TR 546 144



### T ab le 

### D 4

Summary of the Incidence of Nonneoplastic Lesions in Female Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Genital System (continued)

Uterus (50) (50) (50) (50) (50)

Angiectasis 1 (2%) 1 (2%)

Hyperplasia, cystic 43 (86%) 45 (90%) 42 (84%) 43 (86%) 45 (90%)

Inflammation, suppurative 1 (2%)

Serosa, cyst 1 (2%)

Vagina (1)



### Hematopoietic System

Bone marrow (50) (50) (50) (50) (50)

Fibrosis 1 (2%)

Hemorrhage 1 (2%)

Hyperplasia 5 (10%) 3 (6%) 5 (10%) 1 (2%) 1 (2%)

Hyperplasia, reticulum cell 1 (2%)

Pigmentation 47 (94%) 47 (94%) 49 (98%) 49 (98%) 50 (100%)

Lymph node (10) (7) (6) (5) (6)

Bronchial, hyperplasia, lymphoid 1 (10%) 1 (14%) 1 (17%)

Iliac, hematopoietic cell proliferation 1 (10%)

Iliac, hyperplasia, lymphoid 1 (10%) 2 (33%) 1 (20%) 1 (17%)

Iliac, pigmentation 1 (10%)

Mediastinal, hyperplasia, lymphoid 4 (40%) 1 (14%) 2 (33%) 1 (17%)

Renal, hyperplasia, lymphoid 2 (33%)

Lymph node, mandibular (50) (48) (49) (48) (48)

Ectasia 1 (2%)

Hyperplasia, lymphoid 4 (8%) 2 (4%) 4 (8%) 6 (13%) 3 (6%)

Lymph node, mesenteric (46) (48) (46) (50) (50)

Ectasia 6 (13%) 1 (2%) 2 (4%) 2 (4%) 2 (4%)

Hematopoietic cell proliferation 1 (2%) 1 (2%)

Hemorrhage 1 (2%) 1 (2%)

Hyperplasia, lymphoid 3 (7%) 4 (8%) 6 (13%) 4 (8%) 2 (4%)

Infiltration cellular, histiocyte 3 (7%) 29 (60%) 26 (57%) 40 (80%) 42 (84%)

Mineralization 1 (2%)

Lymph, node, pancreatic (14) (12) (15) (14) (13)

Hyperplasia, lymphoid 1 (7%) 1 (8%) 2 (13%) 1 (8%)

Infiltration cellular, histiocyte 1 (8%) 2 (13%) 7 (50%) 8 (62%)

Spleen (48) (48) (50) (50) (50)

Hematopoietic cell proliferation 15 (31%) 24 (50%) 19 (38%) 15 (30%) 15 (30%)

Necrosis 1 (2%)

Lymphoid follicle, atrophy 1 (2%)

Lymphoid follicle, hyperplasia 17 (35%) 19 (40%) 28 (56%) 22 (44%) 18 (36%)

Thymus (46) (38) (43) (40) (47)

Angiectasis 1 (3%)

Atrophy 2 (4%) 1 (3%) 1 (2%)

Hyperplasia, lymphoid 30 (65%) 20 (53%) 17 (40%) 25 (63%) 32 (68%)



### Integumentary System

Mammary gland (50) (48) (50) (50) (50)

Cyst 3 (6%) 1 (2%)

Hyperplasia 1 (2%) 1 (2%)

Duct, cyst 1 (2%)

Skin (50) (50) (50) (49) (50)

Edema 1 (2%)

Inflammation, granulomatous 1 (2%)

Inflammation, chronic 1 (2%)

Ulcer 1 (2%) 1 (2%) 1 (2%)

Dermis, cyst 1 (2%)

### 145 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### D 4

Summary of the Incidence of Nonneoplastic Lesions in Female Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Musculoskeletal System

Bone (50) (50) (50) (50) (50)

Fibrosis 1 (2%)

Cranium, fibrosis 1 (2%)

Cranium, osteopetrosis 1 (2%) 1 (2%)

Skeletal muscle (2) (6) (1) (1) (1)

Fibrosis 1 (100%)



### Nervous System

Brain (50) (50) (50) (50) (50)

Compression 1 (2%) 2 (4%) 2 (4%)

Cerebellum, vacuolization cytoplasmic 1 (2%)

Cerebrum, edema 1 (2%)



### Respiratory System

Lung (50) (50) (50) (50) (50)

Fibrosis 1 (2%)

Hemorrhage 1 (2%) 1 (2%)

Infiltration cellular, histiocyte 2 (4%) 2 (4%) 2 (4%)

Infiltration cellular, lymphocyte 1 (2%) 4 (8%) 6 (12%) 4 (8%) 5 (10%)

Infiltration cellular, mixed cell 1 (2%)

Metaplasia, osseous 1 (2%)

Alveolar epithelium, hyperplasia 1 (2%) 2 (4%) 1 (2%)

Capillary, infiltration cellular, mixed cell 1 (2%)

Nose (50) (50) (50) (50) (50)



### Special Senses System

Eye (49) (48) (48) (46) (50)

Atrophy 1 (2%) 1 (2%)

Harderian gland (49) (49) (50) (50) (50)

Hyperplasia, focal 1 (2%) 1 (2%) 1 (2%)

Inflammation, chronic 1 (2%)



### Urinary System

Kidney (50) (49) (50) (49) (50)

Accumulation, hyaline droplet 1 (2%)

Calculus microscopic observation only 4 (8%) 3 (6%) 5 (10%)

Casts protein 1 (2%)

Cyst 2 (4%) 1 (2%)

Hemorrhage 1 (2%) 1 (2%)

Hydronephrosis 1 (2%) 2 (4%) 1 (2%)

Infarct 4 (8%) 3 (6%) 2 (4%) 2 (4%)

Infiltration cellular 1 (2%) 1 (2%) 2 (4%)

Infiltration cellular, lymphocyte 10 (20%) 5 (10%) 10 (20%) 10 (20%) 7 (14%)

Inflammation, chronic 1 (2%) 2 (4%)

Metaplasia, osseous 1 (2%) 1 (2%) 3 (6%) 1 (2%)

Mineralization 2 (4%) 1 (2%)

Nephropathy 21 (42%) 30 (61%) 30 (60%) 26 (53%) 28 (56%)

Papilla, necrosis 1 (2%) 1 (2%)

Renal tubule, accumulation, hyaline droplet 1 (2%)

Renal tubule, mineralization 1 (2%)

Renal tubule, pigmentation 1 (2%)

### Sodium Dichromate Dihydrate, NTP TR 546 146



### T ab le 

### D 4

Summary of the Incidence of Nonneoplastic Lesions in Female Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Urinary System (continued)

Ureter (1)

Urinary bladder (50) (48) (50) (48) (49)

Infiltration cellular, lymphocyte 42 (84%) 33 (69%) 37 (74%) 27 (56%) 38 (78%)

### 147



# APPENDIX E

CLINICAL PATHOLOGY RESULTS

T ab le 

### E 1 Hematology and Clinical Chemistry Data for Male Rats

in the 2-Year Drinking Water Study of Sodium Dichromate Dihydrate

. . . . . . . . . . . . . . . 148

T ab le 

### E 2 Hematology Data for Female Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153

### Sodium Dichromate Dihydrate, NTP TR 546 148



### T ab le 

### E 1

Hematology and Clinical Chemistry Data for Male Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate a



### 0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Hematology

n

Day 4 9 10 9 10 10

Day 22 10 10 10 10 10

Month 3 10 10 10 10 10

Month 6 10 10 10 10 10

Month 12 10 10 10 8 10

Hematocrit (auto) (%)

Day 4 37.5 ± 0.5 37.7 ± 0.5 36.4 ± 0.8 35.8 ± 0.7 37.0 ± 0.6

Day 22 46.5 ± 0.9 45.3 ± 0.5 44.2 ± 0.7 38.4 ± 0.8** 28.0 ± 0.6**

Month 3 45.1 ± 0.3 44.6 ± 0.4 44.7 ± 0.5 44.6 ± 0.5 43.0 ± 0.5**

Month 6 46.5 ± 0.3 46.7 ± 0.5 46.3 ± 0.5 46.5 ± 0.4 46.0 ± 0.3

Month 12 48.8 ± 0.6 48.0 ± 0.4 48.8 ± 0.7 49.3 ± 0.5 48.6 ± 0.4

Hematocrit (spun) (%)

Day 4 38.2 ± 0.5 b 38.4 ± 0.6 36.7 ± 0.9 36.4 ± 0.6 37.3 ± 0.6

Day 22 46.0 ± 1.1 44.4 ± 0.4 43.2 ± 0.6* 38.7 ± 0.6** 33.5 ± 0.8**

Month 3 45.3 ± 0.4 44.5 ± 0.3 44.5 ± 0.4 44.1 ± 0.5 41.0 ± 0.5**

Month 6 45.9 ± 0.4 45.7 ± 0.5 45.5 ± 0.4 45.5 ± 0.5 45.0 ± 0.3

Month 12 47.6 ± 0.5 46.6 ± 0.4 47.4 ± 0.5 47.7 ± 0.4 47.3 ± 0.4

Hemoglobin (g/dL)

Day 4 12.9 ± 0.2 13.0 ± 0.2 12.5 ± 0.3 12.3 ± 0.2 12.8 ± 0.2

Day 22 15.5 ± 0.3 15.1 ± 0.2 14.2 ± 0.2** 12.0 ± 0.3** 10.1 ± 0.2**

Month 3 15.1 ± 0.1 14.9 ± 0.1 14.9 ± 0.2 14.6 ± 0.2* 12.9 ± 0.2**

Month 6 15.2 ± 0.1 15.2 ± 0.2 15.0 ± 0.2 14.9 ± 0.1 14.5 ± 0.1**

Month 12 15.8 ± 0.2 15.4 ± 0.2 15.6 ± 0.2 15.6 ± 0.2 15.3 ± 0.1*

Erythrocytes (10 6 / μ L)

Day 4 6.75 ± 0.11 6.80 ± 0.10 6.67 ± 0.17 6.73 ± 0.11 6.98 ± 0.12

Day 22 7.80 ± 0.13 7.74 ± 0.15 8.06 ± 0.16 8.10 ± 0.14 6.21 ± 0.13**

Month 3 9.28 ± 0.05 9.24 ± 0.06 9.46 ± 0.11 9.75 ± 0.11** 10.93 ± 0.16**

Month 6 9.34 ± 0.06 9.43 ± 0.08 9.54 ± 0.11 9.71 ± 0.08** 10.15 ± 0.13**

Month 12 9.27 ± 0.10 9.17 ± 0.07 9.40 ± 0.12 9.61 ± 0.11 9.74 ± 0.08**

Reticulocytes (auto) (10 6 / μ L)

Day 4 0.62 ± 0.04 0.56 ± 0.04 0.50 ± 0.04 0.24 ± 0.02** 0.19 ± 0.02**

Day 22 0.38 ± 0.03 0.34 ± 0.02 0.38 ± 0.03 0.43 ± 0.04 0.63 ± 0.07**

Month 3 0.23 ± 0.01 0.24 ± 0.01 0.22 ± 0.01 0.21 ± 0.01 0.30 ± 0.01**

Month 6 0.24 ± 0.00 0.22 ± 0.01 0.22 ± 0.01 0.24 ± 0.01 0.24 ± 0.01

Month 12 0.23 ± 0.01 0.23 ± 0.01 0.24 ± 0.01 0.26 ± 0.02 0.23 ± 0.01

Reticulocytes (manual) (10 6 / μ L)

Day 4 0.30 ± 0.06 0.29 ± 0.03 0.29 ± 0.06 0.30 ± 0.03 0.27 ± 0.02

Day 22 0.32 ± 0.04 0.27 ± 0.03 0.30 ± 0.03 0.41 ± 0.05 0.52 ± 0.04**

Month 3 0.12 ± 0.02 0.14 ± 0.02 0.10 ± 0.02 0.11 ± 0.03 0.13 ± 0.02

Month 12 0.19 ± 0.02 0.18 ± 0.01 0.21 ± 0.02 0.22 ± 0.03 0.17 ± 0.01

Nucleated erythrocytes (10 3 / μ L)

Day 4 0.50 ± 0.17 b 0.60 ± 0.22 0.20 ± 0.13 b 0.50 ± 0.17 0.10 ± 0.10

Day 22 0.20 ± 0.13 0.20 ± 0.13 0.30 ± 0.15 0.30 ± 0.21 1.40 ± 0.22**

Month 3 0.20 ± 0.13 0.40 ± 0.22 0.30 ± 0.21 0.20 ± 0.13 0.00 ± 0.00

Month 6 0.30 ± 0.15 0.10 ± 0.10 0.20 ± 0.13 0.10 ± 0.10 0.40 ± 0.22

Month 12 0.30 ± 0.21 0.30 ± 0.21 0.10 ± 0.10 0.38 ± 0.26 0.10 ± 0.10

### 149 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### E 1

Hematology and Clinical Chemistry Data for Male Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Hematology (continued)

n

Day 4 9 10 9 10 10

Day 22 10 10 10 10 10

Month 3 10 10 10 10 10

Month 6 10 10 10 10 10

Month 12 10 10 10 8 10

Mean cell volume (fL)

Day 4 55.6 ± 0.3 55.5 ± 0.3 54.6 ± 0.3 53.3 ± 0.1** 53.0 ± 0.2**

Day 22 59.5 ± 0.4 58.6 ± 0.5 54.9 ± 0.5** 47.4 ± 0.4** 45.0 ± 0.7**

Month 3 48.6 ± 0.2 48.3 ± 0.2 47.3 ± 0.2** 45.7 ± 0.2** 39.2 ± 0.6**

Month 6 49.8 ± 0.1 49.5 ± 0.1 48.6 ± 0.1** 47.8 ± 0.2** 45.4 ± 0.5**

Month 12 52.6 ± 0.2 52.4 ± 0.2 51.9 ± 0.3 51.4 ± 0.3** 49.9 ± 0.2**

Mean cell hemoglobin (pg)

Day 4 19.1 ± 0.1 19.1 ± 0.1 18.7 ± 0.1* 18.3 ± 0.1** 18.4 ± 0.1**

Day 22 19.8 ± 0.1 19.5 ± 0.2 17.7 ± 0.2** 14.8 ± 0.2** 16.3 ± 0.5**

Month 3 16.2 ± 0.1 16.2 ± 0.1 15.7 ± 0.0** 15.0 ± 0.1** 11.9 ± 0.3**

Month 6 16.3 ± 0.1 16.1 ± 0.1 15.7 ± 0.1** 15.3 ± 0.1** 14.3 ± 0.2**

Month 12 17.0 ± 0.1 16.8 ± 0.1 16.6 ± 0.1* 16.2 ± 0.1** 15.7 ± 0.1**

Mean cell hemoglobin concentration (g/dL)

Day 4 34.4 ± 0.2 34.4 ± 0.2 34.3 ± 0.2 34.4 ± 0.2 34.7 ± 0.2

Day 22 33.3 ± 0.1 33.3 ± 0.1 32.2 ± 0.2 31.2 ± 0.2** 36.2 ± 0.8

Month 3 33.4 ± 0.1 33.5 ± 0.2 33.2 ± 0.1 32.7 ± 0.1** 30.2 ± 0.3**

Month 6 32.7 ± 0.1 32.5 ± 0.1 32.3 ± 0.1* 32.1 ± 0.1** 31.6 ± 0.2**

Month 12 32.3 ± 0.2 32.1 ± 0.3 32.0 ± 0.2 31.6 ± 0.2* 31.5 ± 0.2*

Platelets (10 3 / μ L)

Day 4 1,011.0 ± 16.0 1,063.0 ± 27.0 1,068.0 ± 22.0 1,203.0 ± 37.0** 1,172.0 ± 27.0**

Day 22 987.9 ± 32.9 993.3 ± 23.6 1,128.1 ± 58.9 1,847.4 ± 127.4** 3,537.1 ± 199.7**

Month 3 689.7 ± 18.8 714.4 ± 17.0 704.1 ± 15.9 706.8 ± 14.7 898.4 ± 64.9**

Month 6 644.7 ± 9.2 651.5 ± 13.2 649.3 ± 15.7 648.1 ± 22.2 663.8 ± 8.7

Month 12 575.1 ± 10.3 577.5 ± 8.2 579.1 ± 10.1 562.3 ± 21.4 587.1 ± 17.0

Platelet estimates

Day 4 1,397.0 ± 84.0 b 1,439.0 ± 56.0 1,512.0 ± 84.0 1,628.0 ± 80.0 1,401.0 ± 55.0

Day 22 1,199.0 ± 30.0 1,254.0 ± 47.0 1,268.0 ± 55.0 1,237.0 ± 48.0 1,359 ± 44.0

Month 3 949.2 ± 29.7 976.5 ± 31.0 1,010.1 ± 47.3 926.1 ± 22.2 984.9 ± 31.8

Month 6 707.7 ± 38.5 638.4 ± 24.9 688.8 ± 27.3 648.9 ± 25.5 636.3 ± 18.8

Month 12 1,138.2 ± 30.5 1,163.4 ± 29.1 1,089.9 ± 38.3 1,002.8 ± 73.6 999.6 ± 63.1

Leukocytes (10 3 / μ L)

Day 4 9.23 ± 0.40 9.81 ± 0.42 7.94 ± 0.59 8.40 ± 0.46 9.88 ± 0.42

Day 22 10.85 ± 0.31 11.52 ± 0.33 10.29 ± 0.34 11.00 ± 0.48 11.45 ± 0.63

Month 3 11.52 ± 0.21 11.80 ± 0.21 10.88 ± 0.22 11.43 ± 0.23 12.96 ± 0.43*

Month 6 9.99 ± 0.27 9.81 ± 0.23 9.92 ± 0.27 9.19 ± 0.17 10.22 ± 0.27

Month 12 8.74 ± 0.17 8.76 ± 0.15 8.43 ± 0.19 8.45 ± 0.33 7.81 ± 0.12**

Segmented neutrophils (10 3 / μ L)

Day 4 1.08 ± 0.05 1.09 ± 0.07 0.87 ± 0.04* 0.93 ± 0.03 0.98 ± 0.05

Day 22 0.98 ± 0.05 1.06 ± 0.06 0.92 ± 0.03 0.93 ± 0.05 1.05 ± 0.14

Month 3 1.36 ± 0.04 1.47 ± 0.06 1.44 ± 0.04 1.52 ± 0.04* 1.75 ± 0.10**

Month 6 1.54 ± 0.05 1.53 ± 0.05 1.57 ± 0.05 1.54 ± 0.05 1.68 ± 0.03

Month 12 2.22 ± 0.11 2.12 ± 0.07 1.80 ± 0.08** 1.82 ± 0.12* 1.77 ± 0.07**

### Sodium Dichromate Dihydrate, NTP TR 546 150



### T ab le 

### E 1

Hematology and Clinical Chemistry Data for Male Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Hematology (continued)

n

Day 4 9 10 9 10 10

Day 22 10 10 10 10 10

Month 3 10 10 10 10 10

Month 6 10 10 10 10 10

Month 12 10 10 10 8 10

Lymphocytes (10 3 / μ L)

Day 4 7.89 ± 0.37 8.43 ± 0.35 6.83 ± 0.56 7.26 ± 0.45 8.65 ± 0.38

Day 22 9.59 ± 0.27 10.10 ± 0.29 9.05 ± 0.31 9.76 ± 0.45 10.08 ± 0.49

Month 3 9.76 ± 0.19 9.90 ± 0.21 9.04 ± 0.18 9.52 ± 0.23 10.79 ± 0.36

Month 6 7.98 ± 0.24 7.82 ± 0.19 7.92 ± 0.25 7.24 ± 0.17 8.06 ± 0.24

Month 12 6.08 ± 0.14 6.21 ± 0.12 6.23 ± 0.13 6.21 ± 0.26 5.71 ± 0.11

Activated lymphocytes (10 3 / μ L)

Day 4 0.06 ± 0.00 0.06 ± 0.01 0.06 ± 0.01 0.04 ± 0.01 0.07 ± 0.01

Day 22 0.06 ± 0.01 0.07 ± 0.01 0.06 ± 0.01 0.08 ± 0.01 0.07 ± 0.01

Month 3 0.05 ± 0.00 0.06 ± 0.01 0.07 ± 0.00 0.05 ± 0.00 0.06 ± 0.00

Month 6 0.09 ± 0.00 0.09 ± 0.01 0.09 ± 0.01 0.09 ± 0.01 0.10 ± 0.01

Month 12 0.05 ± 0.01 0.05 ± 0.00 0.04 ± 0.00 0.04 ± 0.01 0.04 ± 0.00

Monocytes (10 3 / μ L)

Day 4 0.16 ± 0.01 0.17 ± 0.02 0.14 ± 0.02 0.13 ± 0.01 0.14 ± 0.01

Day 22 0.15 ± 0.01 0.22 ± 0.02* 0.19 ± 0.02 0.19 ± 0.01 0.20 ± 0.03

Month 3 0.22 ± 0.01 0.23 ± 0.01 0.19 ± 0.01 0.21 ± 0.01 0.23 ± 0.01

Month 6 0.24 ± 0.01 0.24 ± 0.01 0.22 ± 0.01 0.21 ± 0.01 0.25 ± 0.01

Month 12 0.27 ± 0.03 0.24 ± 0.02 0.24 ± 0.01 0.25 ± 0.02 0.20 ± 0.01

Basophils (10 3 / μ L)

Day 4 0.029 ± 0.002 0.031 ± 0.003 0.031 ± 0.004 0.029 ± 0.003 0.034 ± 0.003

Day 22 0.032 ± 0.003 0.040 ± 0.004 0.034 ± 0.003 0.027 ± 0.003 0.028 ± 0.003

Month 3 0.056 ± 0.004 0.060 ± 0.006 0.052 ± 0.004 0.054 ± 0.002 0.048 ± 0.003

Month 6 0.044 ± 0.004 0.043 ± 0.003 0.037 ± 0.003 0.035 ± 0.003 0.048 ± 0.010

Month 12 0.031 ± 0.004 0.038 ± 0.004 0.029 ± 0.004 0.021 ± 0.004 0.021 ± 0.002

Eosinophils (10 3 / μ L)

Day 4 0.02 ± 0.00 0.03 ± 0.00 0.02 ± 0.00 0.02 ± 0.00 0.02 ± 0.00

Day 22 0.04 ± 0.00 0.04 ± 0.00 0.03 ± 0.00* 0.02 ± 0.00** 0.02 ± 0.01**

Month 3 0.08 ± 0.01 0.08 ± 0.01 0.09 ± 0.01 0.08 ± 0.00 0.08 ± 0.01

Month 6 0.09 ± 0.01 0.08 ± 0.00 0.08 ± 0.01 0.07 ± 0.01 0.08 ± 0.01

Month 12 0.09 ± 0.01 0.10 ± 0.01 0.09 ± 0.01 0.10 ± 0.01 0.07 ± 0.01

Clinical Chemistry

n

Day 4 10 9 10 10 10

Day 22 10 10 10 10 10

Month 3 10 10 10 10 10

Month 6 10 10 10 10 10

Month 12 10 10 10 10 10

Urea nitrogen (mg/dL)

Day 4 9.1 ± 0.3 9.4 ± 0.3 10.2 ± 0.4* 10.9 ± 0.4** 11.5 ± 0.3**

Day 22 15.6 ± 0.4 15.0 ± 0.5 15.6 ± 0.5 16.0 ± 0.3 16.6 ± 0.3

Month 3 17.8 ± 0.4 16.4 ± 0.6 18.2 ± 0.4 17.5 ± 0.3 17.5 ± 0.4

Month 6 15.7 ± 0.3 15.2 ± 0.4 15.4 ± 0.4 17.1 ± 0.4 15.8 ± 0.2

Month 12 16.1 ± 0.3 16.8 ± 0.3 16.8 ± 0.3 18.2 ± 0.6** 17.7 ± 0.3**

### 151 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### E 1

Hematology and Clinical Chemistry Data for Male Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Clinical Chemistry (continued)

n

Day 4 10 9 10 10 10

Day 22 10 10 10 10 10

Month 3 10 10 10 10 10

Month 6 10 10 10 10 10

Month 12 10 10 10 10 10

Creatinine (mg/dL)

Day 4 0.41 ± 0.01 0.41 ± 0.02 0.44 ± 0.02 0.40 ± 0.00 0.41 ± 0.01

Day 22 0.52 ± 0.02 0.50 ± 0.02 0.52 ± 0.01 0.48 ± 0.02 0.47 ± 0.02

Month 3 0.70 ± 0.02 0.70 ± 0.02 0.69 ± 0.02 0.67 ± 0.02 0.66 ± 0.02

Month 6 0.70 ± 0.02 0.67 ± 0.02 0.62 ± 0.03** 0.65 ± 0.03* 0.62 ± 0.01**

Month 12 0.70 ± 0.03 0.74 ± 0.02 0.78 ± 0.02 0.66 ± 0.02 0.73 ± 0.03

Total protein (g/dL)

Day 4 5.2 ± 0.1 5.3 ± 0.1 5.2 ± 0.2 5.0 ± 0.1 5.0 ± 0.1

Day 22 6.1 ± 0.1 6.1 ± 0.1 6.0 ± 0.1 5.8 ± 0.1 5.7 ± 0.1*

Month 3 6.9 ± 0.1 6.9 ± 0.1 6.8 ± 0.1 6.7 ± 0.1 6.6 ± 0.1**

Month 6 6.5 ± 0.2 6.6 ± 0.0 6.6 ± 0.1 6.5 ± 0.1 6.3 ± 0.1*

Month 12 7.2 ± 0.1 7.2 ± 0.1 7.3 ± 0.1 7.0 ± 0.1 6.9 ± 0.1*

Albumin (g/dL)

Day 4 3.7 ± 0.0 3.7 ± 0.1 3.7 ± 0.1 3.6 ± 0.0 3.6 ± 0.0

Day 22 4.2 ± 0.1 4.2 ± 0.0 4.1 ± 0.0 4.1 ± 0.0 4.1 ± 0.0

Month 3 4.5 ± 0.0 4.5 ± 0.0 4.5 ± 0.0 4.5 ± 0.0 4.5 ± 0.0

Month 6 4.5 ± 0.0 4.5 ± 0.0 4.5 ± 0.0 4.5 ± 0.0 4.3 ± 0.0**

Month 12 4.4 ± 0.0 4.5 ± 0.0 4.5 ± 0.0 4.4 ± 0.1 4.4 ± 0.0

Alanine aminotransferase (IU/L)

Day 4 54 ± 2 53 ± 2 60 ± 3 68 ± 1** 70 ± 2**

Day 22 45 ± 1 46 ± 1 58 ± 2** 75 ± 3** 73 ± 4**

Month 3 82 ± 4 82 ± 12 135 ± 18* 176 ± 13** 216 ± 21**

Month 6 122 ± 15 114 ± 9 150 ± 12 238 ± 20** 210 ± 12**

Month 12 102 ± 6 107 ± 8 135 ± 10* 261 ± 23** 223 ± 15**

Alkaline phosphatase (IU/L)

Day 4 639 ± 16 634 ± 22 592 ± 23 550 ± 11** 504 ± 9**

Day 22 542 ± 19 508 ± 15 498 ± 20 495 ± 19 471 ± 6**

Month 3 219 ± 3 204 ± 5* 195 ± 6** 168 ± 3** 182 ± 7**

Month 6 167 ± 3 160 ± 3 142 ± 5** 129 ± 3** 115 ± 2**

Month 12 146 ± 4 141 ± 3 c 131 ± 8** 112 ± 6** 101 ± 2**

Creatine kinase (IU/L)

Day 4 395 ± 39 405 ± 45 412 ± 15 431 ± 37 486 ± 43

Day 22 392 ± 65 319 ± 15 361 ± 31 334 ± 18 357 ± 42

Month 3 423 ± 41 388 ± 49 495 ± 65 531 ± 50 517 ± 54

Month 6 289 ± 35 293 ± 32 242 ± 14 367 ± 22 399 ± 14*

Month 12 176 ± 17 187 ± 18 184 ± 21 288 ± 28** 305 ± 20**

Sorbitol dehydrogenase (IU/L)

Day 4 17 ± 1 15 ± 1 14 ± 1 15 ± 1 13 ± 1

Day 22 11 ± 1 10 ± 1 10 ± 1 9 ± 1 10 ± 1

Month 3 18 ± 3 20 ± 5 21 ± 4 28 ± 4 30 ± 4

Month 6 29 ± 2 27 ± 3 31 ± 2 49 ± 5** 36 ± 2*

Month 12 27 ± 1 27 ± 1 27 ± 1 31 ± 3 27 ± 0

### Sodium Dichromate Dihydrate, NTP TR 546 152



### T ab le 

### E 1

Hematology and Clinical Chemistry Data for Male Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

Clinical Chemistry (continued)

n

Day 4 10 9 10 10 10

Day 22 10 10 10 10 10

Month 3 10 10 10 10 10

Month 6 10 10 10 10 10

Month 12 10 10 10 10 10

Bile acids ( μ mol/L)

Day 4 27.6 ± 2.9 26.9 ± 2.0 29.8 ± 2.1 31.6 ± 2.9 26.6 ± 1.3

Day 22 22.1 ± 1.9 24.5 ± 1.7 22.8 ± 1.5 24.7 ± 1.9 26.8 ± 1.4

Month 3 23.9 ± 3.2 24.0 ± 2.5 22.4 ± 2.2 27.7 ± 3.5 24.2 ± 2.2

Month 6 17.8 ± 1.7 25.5 ± 2.4* 18.7 ± 1.5 22.0 ± 1.7 20.0 ± 1.1

Month 12 29.2 ± 3.2 29.8 ± 4.7 26.8 ± 3.6 39.6 ± 4.2 27.4 ± 2.2

* Significantly different (P # 0.05) from the control group by Dunn’s or Shirley’s test

** P # 0.01

a Mean ± standard error. Statistical tests were performed on unrounded data.

b n=10

c n=9

### 153 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### E 2

Hematology Data for Female Mice in the 2-Year Drinking Water Study of Sodium Dichromate Dihydrate a



### 0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

n

Day 22 10 10 10 10 10

Month 3 10 10 10 10 10

Month 6 10 10 10 10 10

Month 12 10 10 9 10 10

Hematocrit (auto) (%)

Day 22 50.0 ± 0.7 49.2 ± 0.4 50.0 ± 0.9 50.6 ± 0.7 49.6 ± 0.5

Month 3 47.7 ± 0.7 49.9 ± 0.5* 49.2 ± 0.8 49.4 ± 0.6 50.4 ± 0.5*

Month 6 48.4 ± 0.7 49.2 ± 0.5 47.8 ± 0.6 48.0 ± 0.8 49.2 ± 0.8

Month 12 45.0 ± 0.5 45.6 ± 0.3 45.2 ± 0.6 45.0 ± 0.7 45.1 ± 0.8

Hematocrit (spun) (%)

Day 22 50.0 ± 0.7 49.0 ± 0.3 49.4 ± 0.8 49.6 ± 0.7 48.5 ± 0.5

Month 3 48.3 ± 0.6 50.4 ± 0.5* 49.3 ± 0.6 49.4 ± 0.5 50.4 ± 0.4*

Month 6 49.0 ± 0.6 50.2 ± 0.5 48.7 ± 0.5 48.9 ± 0.8 49.9 ± 0.7

Month 12 46.5 ± 0.4 47.4 ± 0.2 46.9 ± 0.5 46.4 ± 0.6 46.7 ± 0.6

Hemoglobin (g/dL)

Day 22 16.8 ± 0.2 16.5 ± 0.1 16.7 ± 0.3 16.9 ± 0.2 16.4 ± 0.2

Month 3 16.0 ± 0.2 16.7 ± 0.2* 16.4 ± 0.3 16.3 ± 0.2 16.5 ± 0.2

Month 6 16.1 ± 0.2 16.4 ± 0.2 16.0 ± 0.2 16.0 ± 0.3 16.2 ± 0.3

Month 12 14.9 ± 0.1 15.3 ± 0.2 15.1 ± 0.2 15.0 ± 0.2 14.9 ± 0.3

Erythrocytes (10 6 / μ L)

Day 22 10.25 ± 0.15 10.20 ± 0.08 10.47 ± 0.19 10.77 ± 0.13* 10.61 ± 0.13*

Month 3 10.10 ± 0.16 10.66 ± 0.13* 10.55 ± 0.17* 10.95 ± 0.10** 11.55 ± 0.16**

Month 6 10.56 ± 0.15 10.81 ± 0.10 10.60 ± 0.13 10.77 ± 0.20 11.50 ± 0.20**

Month 12 9.58 ± 0.10 9.72 ± 0.09 9.77 ± 0.10 9.95 ± 0.13* 10.30 ± 0.21**

Reticulocytes (auto) (10 6 / μ L)

Day 22 0.32 ± 0.01 0.30 ± 0.01 0.33 ± 0.02 0.31 ± 0.01 0.32 ± 0.02

Month 3 0.33 ± 0.01 0.31 ± 0.01 0.34 ± 0.02 0.34 ± 0.03 0.34 ± 0.02

Month 6 0.36 ± 0.02 0.37 ± 0.01 0.39 ± 0.04 0.36 ± 0.03 0.35 ± 0.02

Month 12 0.32 ± 0.02 0.33 ± 0.01 0.32 ± 0.01 0.36 ± 0.02 0.37 ± 0.02

Reticulocytes (manual) (10 6 / μ L)

Day 22 0.21 ± 0.04 0.12 ± 0.02 0.16 ± 0.02 0.11 ± 0.01* 0.14 ± 0.02

Month 3 0.25 ± 0.02 b 0.19 ± 0.03 0.21 ± 0.03 c 0.24 ± 0.02 0.23 ± 0.02

Nucleated erythrocytes (10 3 / μ L)

Day 22 0.00 ± 0.00 0.00 ± 0.00 0.00 ± 0.00 0.00 ± 0.00 0.00 ± 0.00

Month 3 0.00 ± 0.00 0.10 ± 0.10 0.00 ± 0.00 0.00 ± 0.00 0.00 ± 0.00

Month 6 0.10 ± 0.10 0.10 ± 0.10 0.00 ± 0.00 0.00 ± 0.00 0.00 ± 0.00

Month 12 0.00 ± 0.00 c 0.00 ± 0.00 0.00 ± 0.00 0.00 ± 0.00 0.00 ± 0.00 c

Mean cell volume (fL)

Day 22 48.8 ± 0.2 48.3 ± 0.1* 47.8 ± 0.2** 47.0 ± 0.2** 46.8 ± 0.2**

Month 3 47.2 ± 0.1 46.9 ± 0.3 46.7 ± 0.1 45.1 ± 0.2** 43.7 ± 0.3**

Month 6 45.8 ± 0.2 45.5 ± 0.3 45.1 ± 0.2* 44.6 ± 0.2** 42.8 ± 0.3**

Month 12 46.9 ± 0.3 46.9 ± 0.3 46.3 ± 0.3 45.2 ± 0.2** 43.9 ± 0.5**

Mean cell hemoglobin (pg)

Day 22 16.4 ± 0.1 16.2 ± 0.0* 15.9 ± 0.1** 15.7 ± 0.1** 15.5 ± 0.1**

Month 3 15.8 ± 0.0 15.7 ± 0.1 15.6 ± 0.0** 14.9 ± 0.1** 14.3 ± 0.1**

Month 6 15.3 ± 0.1 15.2 ± 0.1 15.1 ± 0.1 14.9 ± 0.1** 14.1 ± 0.1**

Month 12 15.5 ± 0.1 15.7 ± 0.2 15.5 ± 0.1 15.1 ± 0.1* 14.4 ± 0.2**

### Sodium Dichromate Dihydrate, NTP TR 546 154



### T ab le 

### E 2

Hematology Data for Female Mice in the 2-Year Drinking Water Study of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

n

Day 22 10 10 10 10 10

Month 3 10 10 10 10 10

Month 6 10 10 10 10 10

Month 12 10 10 9 10 10

Mean cell hemoglobin concentration (g/dL)

Day 22 33.6 ± 0.1 33.5 ± 0.1 33.3 ± 0.2 33.4 ± 0.1 33.1 ± 0.1**

Month 3 33.5 ± 0.1 33.5 ± 0.1 33.3 ± 0.1 33.1 ± 0.1** 32.8 ± 0.1**

Month 6 33.4 ± 0.2 33.4 ± 0.1 33.5 ± 0.2 33.4 ± 0.1 32.9 ± 0.1

Month 12 33.1 ± 0.2 33.5 ± 0.2 33.4 ± 0.1 33.3 ± 0.1 32.9 ± 0.1

Platelets (10 3 / μ L)

Day 22 905.7 ± 48.4 939.2 ± 36.5 933.3 ± 47.4 851.4 ± 54.9 963.9 ± 48.0

Month 3 890.7 ± 37.4 839.5 ± 63.4 837.2 ± 57.0 888.2 ± 73.9 720.0 ± 47.1

Month 6 972.9 ± 62.5 819.3 ± 55.4 928.9 ± 91.0 923.1 ± 55.7 921.4 ± 62.9

Month 12 1,078.1 ± 67.6 925.0 ± 37.9 932.6 ± 78.1 879.9 ± 46.7* 761.5 ± 34.4**

Platelet estimates (10 3 / μ L)

Day 22 1,630.0 ± 105.0 1,903.0 ± 83.0 1,462.0 ± 91.0 1,319.0 ± 61.0 1,825.0 ± 105.0

Month 3 1,296.0 ± 92.0 1,208.0 ± 104.0 1,166.0 ± 81.0 1,342.0 ± 98.0 1,126.0 ± 90.0

Month 6 1,073.1 ± 52.7 998.0 ± 71.8 890.4 ± 74.0 978.6 ± 55.8 940.8 ± 39.5

Month 12 968.3 ± 61.6 c 932.4 ± 57.4 987.0 ± 90.4 915.6 ± 44.8 828.3 ± 44.2 c

Leukocytes (10 3 / μ L)

Day 22 5.10 ± 0.51 6.58 ± 0.35* 7.19 ± 0.49** 7.26 ± 0.57* 7.89 ± 0.39**

Month 3 4.46 ± 0.24 4.48 ± 0.33 5.05 ± 0.30 5.32 ± 0.36 4.74 ± 0.48

Month 6 6.49 ± 0.42 5.69 ± 0.22 6.25 ± 0.51 6.62 ± 0.54 5.30 ± 0.33

Month 12 5.86 ± 0.51 4.84 ± 0.28 5.64 ± 0.35 5.67 ± 0.53 5.12 ± 0.40

Segmented neutrophils (10 3 / μ L)

Day 22 0.48 ± 0.06 0.60 ± 0.03 0.63 ± 0.06 0.75 ± 0.11* 0.83 ± 0.07**

Month 3 0.53 ± 0.04 0.47 ± 0.07 0.60 ± 0.05 0.66 ± 0.05 0.53 ± 0.05

Month 6 0.85 ± 0.08 0.72 ± 0.04 0.80 ± 0.08 0.89 ± 0.07 0.75 ± 0.10

Month 12 1.06 ± 0.11 0.88 ± 0.08 1.03 ± 0.06 0.93 ± 0.07 0.73 ± 0.05**

Lymphocytes (10 3 / μ L)

Day 22 4.36 ± 0.44 5.66 ± 0.32* 6.22 ± 0.41** 6.17 ± 0.46** 6.61 ± 0.33**

Month 3 3.67 ± 0.21 3.68 ± 0.24 4.09 ± 0.28 4.32 ± 0.32 3.85 ± 0.43

Month 6 5.17 ± 0.34 4.61 ± 0.17 4.96 ± 0.42 5.22 ± 0.44 4.14 ± 0.23

Month 12 4.42 ± 0.40 3.62 ± 0.22 4.14 ± 0.33 4.30 ± 0.45 4.05 ± 0.32

Activated lymphocytes (10 3 / μ L)

Day 22 0.02 ± 0.00 0.03 ± 0.00 0.03 ± 0.00 0.03 ± 0.00 0.04 ± 0.00**

Month 3 0.02 ± 0.00 0.02 ± 0.00 0.02 ± 0.00 0.02 ± 0.00 0.02 ± 0.00

Month 6 0.03 ± 0.01 0.03 ± 0.00 0.04 ± 0.01 0.04 ± 0.01 0.02 ± 0.00

Month 12 0.03 ± 0.01 0.02 ± 0.00 0.03 ± 0.01 0.02 ± 0.01 0.02 ± 0.00*

Monocytes (10 3 / μ L)

Day 22 0.08 ± 0.01 0.10 ± 0.01 0.10 ± 0.01 0.12 ± 0.01* 0.16 ± 0.01**

Month 3 0.10 ± 0.01 0.08 ± 0.01 0.09 ± 0.01 0.08 ± 0.00 0.09 ± 0.01

Month 6 0.22 ± 0.02 0.16 ± 0.02 0.18 ± 0.02 0.22 ± 0.02 0.16 ± 0.02

Month 12 0.22 ± 0.02 0.19 ± 0.02 0.25 ± 0.02 0.23 ± 0.03 0.17 ± 0.02

Basophils (10 3 / μ L)

Day 22 0.014 ± 0.003 0.017 ± 0.002 0.023 ± 0.003 0.019 ± 0.002 0.031 ± 0.005**

Month 3 0.024 ± 0.004 0.022 ± 0.003 0.023 ± 0.004 0.022 ± 0.004 0.024 ± 0.003

Month 6 0.015 ± 0.002 0.015 ± 0.003 0.035 ± 0.009 0.021 ± 0.006 0.016 ± 0.003

Month 12 0.016 ± 0.003 0.016 ± 0.003 0.028 ± 0.007 0.031 ± 0.007 0.020 ± 0.003

### 155 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### E 2

Hematology Data for Female Mice in the 2-Year Drinking Water Study of Sodium Dichromate Dihydrate

0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

n

Day 22 10 10 10 10 10

Month 3 10 10 10 10 10

Month 6 10 10 10 10 10

Month 12 10 10 9 10 10

Eosinophils (10 3 / μ L)

Day 22 0.15 ± 0.02 0.18 ± 0.02 0.18 ± 0.02 0.18 ± 0.02 0.22 ± 0.03

Month 3 0.12 ± 0.02 0.21 ± 0.04 0.23 ± 0.04* 0.21 ± 0.02* 0.23 ± 0.03**

Month 6 0.20 ± 0.05 0.16 ± 0.03 0.23 ± 0.04 0.23 ± 0.05 0.21 ± 0.04

Month 12 0.12 ± 0.02 0.11 ± 0.02 0.16 ± 0.03 0.16 ± 0.02 0.13 ± 0.02

* Significantly different (P # 0.05) from the control group by Dunn’s or Shirley’s test

** P # 0.01

a Mean ± standard error. Statistical tests were performed on unrounded data.

b n=8

c n=9

### Sodium Dichromate Dihydrate, NTP TR 546 156

### 157



# APPENDIX F

CHEMICAL CHARACTERIZATION

AND DOSE FORMULATION STUDIES

P r o cur e m ent a nd 

### C harac te r iz a tion o f 

### S odi um 

### D i chr o ma te 

### D i hy d ra te



### . . . . . . . . . . . . . . . . . . . . . . 158

P r ep ara tion a nd 

### A n a l ys i s o f 

### D o s e 

### F o rmu l a tion s



### . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159

F i gur e 

### F1 X-Ray Diffraction Diffractograms of Sodium Dichromate Dihydrate

. . . . . . . . . . . . . . . . . 160

F i gur e 

### F2 Proton-Induced X-Ray Emission Spectrum of Sodium Dichromate Dihydrate

. . . . . . . . . . 160

F i gur e 

### F3 Liquid Chromatography-Inductively Coupled Plasma-Mass Spectrometry

Selected Ion-Current Profiles of Cr III and CR VI in Sodium Dichromate Dihydrate

. . . 161

T ab le 

### F1 Preparation and Storage of Dose Formulations in the 2-Year Drinking Water Studies

of Sodium Dichromate Dihydrate

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162

T ab le 

### F2 Results of Analyses of Dose Formulations Administered to Rats and Mice

in the 2-Year Drinking Water Studies of Sodium Dichromate Dihydrate

. . . . . . . . . . . . . . 163

### 158



# CHEMICAL CHARACTERIZATION

AND DOSE FORMULATION STUDIES

P r o cur e m ent a nd 

# C harac te r iz a tion o f 

# S odi um 

# D i chr o ma te 

# D i hy d ra te

Sodium dichromate dihydrate was obtained from Aldrich Chemical Company (Milwaukee, WI) in two lots

(15301BI and 13822LI). The two lots were combined at the analytical chemistry laboratory, Battelle Memorial

Institute (Columbus, OH), and assigned a new lot number (062001). Lot 062001 was used in the 2-year studies.

Identity and purity analyses were conducted by the analytical chemistry laboratory, the study laboratory (Southern

Research Institute, Birmingham, AL), Galbraith Laboratories, Inc. (Knoxville, TN), and Elemental Analysis Corp.

(Lexington, KY). Reports on analyses performed in support of the sodium dichromate dihydrate studies are on file

at the National Institute of Environmental Health Sciences.

Lot 062001, an orange crystalline solid, was identified as sodium dichromate dihydrate by the analytical chemistry

laboratory using X-ray diffraction (XRD), by the analytical chemistry laboratory and by Galbraith Laboratories,

Inc., using elemental analysis by inductively coupled plasma

- atomic emission spectroscopy (ICP

- AES), and by

Elemental Analysis Corp. using proton-induced X-ray emission spectroscopy (PIXE). The XRD powder patterns

were consistent with a reference pattern (International Centre for Diffraction Data, 2000); XRD diffractograms

are presented in Figure F1. Elemental analyses for chromium and sodium by ICP-AES were in agreement with

the theoretical values for sodium dichromate dihydrate, and PIXE indicated the absence of significant metallic

impurities. A PIXE spectrum is presented in Figure F2.

The moisture content of lot 062001 was determined by Galbraith Laboratories, Inc., using Karl Fischer titration.

The purity of lot 062001 was determined by the analytical chemistry laboratory using differential scanning

calorimetry (DSC), titration of the dichromate ion with sodium thiosulfate and potassium ferrocyanide, and

speciation of the chromium ions using liquid chromatography-inductively coupled plasma-mass spectrometry

(LC

- ICP-MS) and by the study laboratory using potentiometric titration with sodium thiosulfate. DSC was

performed using a Perkin-Elmer DSC-7 scanning calorimeter from 342° to 365° C with a temperature increase

of 1° C per minute under a nitrogen atmosphere. Titration with sodium thiosulfate was performed by titrating

a solution of sodium dichromate dihydrate and potassium iodide in dilute hydrochloric acid with 0.1 N sodium

thiosulfate using a double sheet platinum electrode and a Brinkman Metrohm titrator or its equivalent. Titration

with potassium ferrocyanide was performed by titrating a solution of sodium dichromate dihydrate with

0.1 N potassium ferrocyanide trihydrate as previously described. LC-ICP-MS was conducted using system A.

A) Hewlett-Packard (Palo Alto, CA) 1100 series high performance liquid chromatography system, a

Dionex Corp. (Sunnyvale, CA) IonPac ® 

### AS7 ion exchange column (250 mm × 4 mm), with an

isocratic mobile phase of 35 mM ammonium sulfate adjusted to pH 9.2 with ammonium hydroxide at

a flow rate of 1 mL/minute and ICP

- MS detection

Karl Fischer titration indicated a water content of 11.62%, which is in agreement with the theoretical value of

12.09%. DSC indicated a purity of 99.73% ± 0.15%. Titration with sodium thiosulfate by the analytical chemistry

laboratory indicated a purity of 99.7% ± 0.1%. Titration with sodium thiosulfate by the study laboratory indicated

purities of 101% and 102% relative to a frozen reference standard of the same lot. Titration with potassium

ferrocyanide indicated a purity of 103.1% ± 0.2%. LC-ICP-MS indicated that the concentration of Cr III, if

present, was less than 0.1%. Representative LC-ICP-MS spectra are presented in Figure F3. The overall purity of

lot 062001 was determined to be greater than 99.7%.

To ensure stability, the bulk chemical was stored at room temperature, protected from light in amber glass bottles.

Periodic reanalyses of the bulk chemical were performed by the study laboratory using potentiometric titration as

described for the purity assays; no degradation of the bulk chemical was detected. Sodium Dichromate Dihydrate, NTP TR 546

### Sodium Dichromate Dihydrate, NTP TR 546 159



# P r ep ara tion a nd 

# A n a l ys i s o f 

# D o s e 

# F o rmu l a tion s

The dose formulations were prepared approximately every 2 weeks by mixing sodium dichromate dihydrate with

tap water (Table F1). Formulations were stored in NALGENE ® 

### containers at room temperature for up to 42 days.

Because all dose formulations in these studies were determined to be solutions, no homogeneity studies were

required. Stability studies of a 41.8 μg/mL dose formulation were performed by the analytical chemistry

laboratory using ion chromatography by system B. Stability was confirmed for at least 42 days for dose

formulations stored in sealed NALGENE ® 

### containers, protected from light, at temperatures up to room temperature

and for at least 7 days when stored in drinking water bottles under simulated animal room conditions.

B) Dionex Corp. IonPac ® 

### AS7 ion exchange column (250 mm × 4 mm), using an

isocratic mobile phase of 250 mM ammonium sulfate and 100 mM ammonium hydroxide at a flow rate of

1 mL/minute, with postcolumn derivitization using 2 mM 1,5-diphenylcarbazide in

methanol:water:concentrated sulfuric acid (100:872:28) at a flow rate of 0.5 mL/minute and visible light

(520 nm) detection

Periodic analyses of the dose formulations of sodium dichromate dihydrate were conducted by the study laboratory

using ultraviolet/visible/near infrared spectroscopy (350 to 390 nm). The dose formulations were analyzed

approximately every 10 weeks (Table F2). Of the dose formulations analyzed, all 44 for rats and all 84 for mice

were within 10% of the target concentrations. Animal room samples and unused carboy storage samples of these

dose formulations were also analyzed; all 16 animal room samples for rats and 34 of 35 animal room samples for

mice were within 10% of the target concentrations. Fourteen of 16 carboy samples for rats and 33 of 35 carboy

samples for mice were within 10% of the target concentrations.

The sodium dichromate dihydrate dosed water used in these studies was slightly acidic. Based on an equilibrium

constant of 50, dichromate predominates at the highest exposure concentration and the chromate:dichromate ratio

approaches 1 at the lowest exposure concentration.

### 160 Sodium Dichromate Dihydrate, NTP TR 546



### F i gur e 

### F1

X-Ray Diffraction Diffractograms of Sodium Dichromate Dihydrate

Upper plot: lot 062001. Lower plot: reference sample

F i gur e 

### F2

Proton-Induced X-Ray Emission Spectrum of Sodium Dichromate Dihydrate

### Sodium Dichromate Dihydrate, NTP TR 546 161



### F i gur e 

### F3

Liquid Chromatography-Inductively Coupled Plasma-Mass Spectrometry

Selected Ion-Current Profiles of Cr III and Cr VI in Sodium Dichromate Dihydrate

### 162 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### F1

Preparation and Storage of Dose Formulations in the 2-Year Drinking Water Studies

of Sodium Dichromate Dihydrate

Preparation

A premix was prepared in a beaker with tap water and then thoroughly mixed with additional tap water in a mixing tank. The dose

formulations were prepared approximately every 2 weeks.



### Chemical Lot Number

062001



### Maximum Storage Time

42 days



### Storage Conditions

Stored in NALGENE ® containers at room temperature and protected from light



### Study Laboratory

Southern Research Institute (Birmingham, AL)

### Sodium Dichromate Dihydrate, NTP TR 546 163



### T ab le 

### F2

Results of Analyses of Dose Formulations Administered to Rats and Mice

in the 2-Year Drinking Water Studies of Sodium Dichromate Dihydrate

Target Determined Difference

Date Prepared Date Analyzed Concentration Concentration a 

### from Target

(mg/L) (mg/L) (%)

Rats

September 18, 2002 September 19, 2002 14.3 14.0 –2

57.3 59.8 +4

172 172 0

516 517 0

October 16, 2002 b 14.3 14.0 –2

57.3 60.8 +6

172 177 +3

516 529 +3

October 16, 2002 c 14.3 14.7 +3

57.3 61.7 +8

172 179 +4

516 531 +3

November 27, 2002 December 2, 2002 14.3 14.4 +1

57.3 59.5 +4

172 175 +2

516 521 +1

February 5, 2003 February 6 and 10, 2003 14.3 15.3 +7

57.3 60.3 +5

172 189 +10

516 523 +1

April 18, 2003 April 21, 2003 14.3 14.6 +2

57.3 59.7 +4

172 174 +1

516 526 +2

May 14, 2003 b 14.3 13.3 –7

57.3 59.7 +4

172 177 +3

516 522 +1

May 14, 2003 c 14.3 15.0 +5

57.3 62.0 +8

172 191 +11

516 520 +1

June 27, 2003 June 30, 2003 14.3 15.0 +5

57.3 59.4 +4

172 175 +2

516 519 +1

September 5, 2003 September 8, 2003 14.3 14.8 +3

57.3 59.8 +4

172 175 +2

516 520 +1

### 164 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### F2

Results of Analyses of Dose Formulations Administered to Rats and Mice

in the 2-Year Drinking Water Studies of Sodium Dichromate Dihydrate

Target Determined Difference

Date Prepared Date Analyzed Concentration Concentration from Target

(mg/L) (mg/L) (%)

Rats (continued)

November 14, 2003 November 17, 2003 14.3 14.0 –2

57.3 58.0 +1

172 171 –1

516 515 0

December 10, 2003 b 14.3 14.4 +1

57.3 57.5 0

172 175 +2

516 513 –1

December 10, 2003 c 14.3 14.8 +3

57.3 57.6 +1

172 173 +1

516 523 +1

January 23, 2004 January 26, 2004 14.3 15.6 +9

57.3 59.2 +3

172 173 +1

516 515 0

April 2, 2004 April 5, 2004 14.3 15.3 +7

57.3 59.6 +4

172 175 +2

516 521 +1

June 11, 2004 June 14, 2004 14.3 14.2 –1

57.3 59.7 +4

172 177 +3

516 529 +3

July 8, 2004 b 14.3 14.6 +2

57.3 63.1 +10

172 185 +8

516 546 +6

July 8, 2004 c 14.3 14.9 +4

57.3 65.6 +14

172 186 +8

516 550 +7

August 20, 2004 August 23, 2004 14.3 14.4 +1

57.3 58.9 +3

172 176 +2

516 526 +2

### Sodium Dichromate Dihydrate, NTP TR 546 165



### T ab le 

### F2

Results of Analyses of Dose Formulations Administered to Rats and Mice

in the 2-Year Drinking Water Studies of Sodium Dichromate Dihydrate

Target Determined Difference

Date Prepared Date Analyzed Concentration Concentration from Target

(mg/L) (mg/L) (%)

Mice

August 20, 2002 August 22, 2002 14.3 14.4 +1

28.6 29.3 +2

57.3 57.3 0

85.7 87.9 +3

172 169 –2

257.4 261 +1

516 517 0

September 19, 2002 b 14.3 14.4 +1

28.6 29.0 +1

57.3 57.5 0

85.7 87.1 +2

172 132 –23

257.4 265 +3

516 515 0

September 19, 2002 c 14.3 14.3 0

28.6 29.1 +2

57.3 57.6 +1

85.7 87.3 +2

172 169 –2

257.4 265 +3

516 517 0

September 18, 2002 September 19, 2002 14.3 14.0 –2

28.6 28.1 –2

57.3 59.8 +4

85.7 85.0 –1

172 172 0

257.4 254 –1

516 517 0

October 16, 2002 b 14.3 14.7 +3

28.6 29.2 +2

57.3 61.4 +7

85.7 88.6 +3

172 177 +3

257.4 264 +3

516 524 +2

October 16, 2002 c 14.3 14.7 +3

28.6 29.7 +4

57.3 61.7 +8

85.7 89.1 +4

172 179 +4

257.4 264 +3

516 531 +3

### 166 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### F2

Results of Analyses of Dose Formulations Administered to Rats and Mice

in the 2-Year Drinking Water Studies of Sodium Dichromate Dihydrate

Target Determined Difference

Date Prepared Date Analyzed Concentration Concentration from Target

(mg/L) (mg/L) (%)

Mice (continued)

November 27, 2002 December 2, 2002 14.3 14.4 +1

28.6 29.8 +4

57.3 59.5 +4

85.7 88.7 +4

172 175 +2

257.4 266 +3

516 521 +1

February 5, 2003 February 6 and 10, 2003 14.3 15.3 +7

28.6 29.2 +2

57.3 60.3 +5

85.7 91.1 +6

172 189 +10

257.4 268 +4

516 523 +1

April 18, 2003 April 21, 2003 14.3 14.6 +2

28.6 29.3 +2

57.3 59.7 +4

85.7 85.9 0

172 174 +1

257.4 258 0

516 526 +2

May 14, 2003 b 14.3 13.7 –4

28.6 29.4 +3

57.3 58.8 +3

85.7 88.6 +3

172 177 +3

257.4 259 +1

516 518 0

May 14, 2003 c 14.3 15.0 +5

28.6 30.1 +5

57.3 62.0 +8

85.7 89.2 +4

172 191 +11

257.4 262 +2

516 520 +1

June 27, 2003 June 30, 2003 14.3 15.0 +5

28.6 28.8 +1

57.3 59.4 +4

85.7 88.2 +3

172 175 +2

257.4 250 –3

516 519 +1

### T ab le 

### F2

Results of Analyses of Dose Formulations Administered to Rats and Mice

in the 2-Year Drinking Water Studies of Sodium Dichromate Dihydrate

Target Determined Difference

Date Prepared Date Analyzed Concentration Concentration from Target

(mg/L) (mg/L) (%)

Mice (continued)

September 5, 2003 September 8, 2003 14.3 14.8 +3

28.6 28.5 0

57.3 59.8 +4

85.7 86.0 0

172 175 +2

257.4 258 0

516 520 +1

November 14, 2003 November 17, 2003 14.3 14.0 –2

28.6 28.8 +1

57.3 58.0 +1

85.7 82.9 –3

172 171 –1

257.4 255 –1

516 515 0

December 10, 2003 b 14.3 14.7 +3

28.6 29.5 +3

57.3 57.7 +1

85.7 85.8 0

172 177 +3

257.4 256 –1

516 511 –1

December 10, 2003 c 14.3 14.8 +3

28.6 29.5 +3

57.3 57.6 +1

85.7 85.4 0

172 173 +1

257.4 253 –2

516 523 +1

January 23, 2004 January 26, 2004 14.3 15.6 +9

28.6 30.0 +5

57.3 59.2 +3

85.7 90.9 +6

172 173 +1

257.4 257 0

516 515 0

April 2, 2004 April 5, 2004 14.3 15.3 +7

28.6 28.9 +1

57.3 59.6 +4

85.7 87.9 +3

172 175 +2

257.4 256 –1

516 521 +1 

### Sodium Dichromate Dihydrate, NTP TR 546 167

### 168 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### F2

Results of Analyses of Dose Formulations Administered to Rats and Mice

in the 2-Year Drinking Water Studies of Sodium Dichromate Dihydrate

Target Determined Difference

Date Prepared Date Analyzed Concentration Concentration from Target

(mg/L) (mg/L) (%)

Mice (continued)

June 11, 2004 June 14, 2004 14.3 14.2 –1

28.6 28.9 +1

57.3 59.7 +4

85.7 85.8 0

172 177 +3

257.4 261 +1

516 529 +3

July 8, 2004 b 14.3 14.6 +2

28.6 30.8 +8

57.3 62.8 +10

85.7 92.2 +8

172 185 +8

257.4 277 +8

516 546 +6

July 8, 2004 c 14.3 14.9 +4

28.6 31.0 +8

57.3 65.6 +14

85.7 91.9 +7

172 186 +8

257.4 275 +7

516 550 +7

August 20, 2004 August 23, 2004 14.3 14.4 +1

28.6 28.9 +1

57.3 58.9 +3

85.7 85.8 0

172 176 +2

257.4 254 –1

516 526 +2

a Results of duplicate analyses

b Animal room samples from drinking water bottles

c Unused samples from carboy storage containers

### 169



# APPENDIX G

WATER AND COMPOUND CONSUMPTION

IN THE 2-YEAR DRINKING WATER STUDIES

OF SODIUM DICHROMATE DIHYDRATE

T ab le 

### G1 Water and Compound Consumption by Male Rats

in the 2-Year Drinking Water Study of Sodium Dichromate Dihydrate

. . . . . . . . . . . . . . . 170

T ab le 

### G2 Water and Compound Consumption by Female Rats

in the 2-Year Drinking Water Study of Sodium Dichromate Dihydrate

. . . . . . . . . . . . . . . 172

T ab le 

### G3 Water and Compound Consumption by Male Mice

in the 2-Year Drinking Water Study of Sodium Dichromate Dihydrate

. . . . . . . . . . . . . . . 174

T ab le 

### G4 Water and Compound Consumption by Female Mice

in the 2-Year Drinking Water Study of Sodium Dichromate Dihydrate

. . . . . . . . . . . . . . . 176

### 170



### T ab le 

### G1

Water and Compound Consumption by Male Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

Weeks 0 mg/L 14.3 mg/L 57.3 mg/L

on Water Body Water Body Dose Water Body Dose

Study (g/day) a 

### Weight (g/day) Weight (mg/kg) b 

### (g/day) Weight (mg/kg)

(g) (g) (g)

1 16.7 118 16.6 117 2.0 16.0 117 7.9

2 17.1 151 17.2 149 1.7 16.9 146 6.6

3 19.5 185 19.3 183 1.5 19.0 181 6.0

4 19.4 218 19.0 215 1.3 19.3 213 5.2

5 18.7 243 18.7 240 1.1 18.5 239 4.4

6 18.4 261 17.8 257 1.0 17.8 257 4.0

7 18.0 275 17.7 271 0.9 17.3 272 3.6

8 18.1 289 18.1 286 0.9 17.2 285 3.5

9 18.0 305 18.2 301 0.9 17.3 302 3.3

10 18.0 317 18.0 312 0.8 17.3 313 3.2

11 17.6 334 17.4 329 0.8 16.7 331 2.9

12 17.7 345 17.1 340 0.7 17.0 339 2.9

13 17.3 351 17.7 345 0.7 17.2 348 2.8

17 16.2 387 16.2 381 0.6 15.9 383 2.4

21 16.7 410 16.5 404 0.6 16.3 407 2.3

25 16.6 434 16.1 427 0.5 15.9 431 2.1

29 17.2 451 17.0 443 0.5 16.7 448 2.1

33 17.4 468 17.3 458 0.5 17.1 464 2.1

37 16.8 480 16.2 471 0.5 16.1 477 1.9

41 14.8 488 14.6 478 0.4 14.8 483 1.8

45 15.6 490 15.4 485 0.5 16.4 488 1.9

49 16.0 501 16.1 493 0.5 16.5 497 1.9

53 16.4 511 17.1 502 0.5 16.9 505 1.9

57 17.3 515 17.2 507 0.5 17.4 512 1.9

61 16.7 523 16.9 515 0.5 17.1 519 1.9

65 16.5 524 16.1 515 0.4 16.7 519 1.8

69 15.7 525 16.1 516 0.4 16.0 518 1.8

73 15.7 525 15.7 517 0.4 16.1 520 1.8

77 17.0 530 16.2 519 0.4 16.6 525 1.8

81 16.3 532 16.4 518 0.5 16.1 525 1.8

85 15.9 531 16.1 515 0.4 16.0 522 1.8

89 16.2 527 16.4 518 0.5 15.6 518 1.7

93 17.4 526 18.2 517 0.5 18.7 520 2.1

97 15.7 513 16.5 515 0.5 15.9 517 1.8

101 18.1 515 16.2 503 0.5 16.7 514 1.9

Mean for weeks

1-13 18.0 261 17.9 257 1.1 17.5 257 4.3

14-52 16.4 457 16.2 449 0.5 16.2 453 2.1

53-101 16.5 523 16.5 514 0.5 16.6 518 1.8 

### Sodium Dichromate Dihydrate, NTP TR 546

### Sodium Dichromate Dihydrate, NTP TR 546 171



### T ab le 

### G1

Water and Compound Consumption by Male Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

Weeks 172 mg/L 516 mg/L

on Water Body Dose Water Body Dose

Study (g/day) Weight (mg/kg) (g/day) Weight (mg/kg)

(g) (g)

1 14.4 117 21.2 12.6 118 55.2

2 15.0 147 17.5 13.2 143 47.8

3 16.8 180 16.1 14.9 173 44.4

4 16.6 210 13.6 14.8 201 37.9

5 16.3 235 11.9 14.7 225 33.7

6 15.5 254 10.5 14.2 243 30.2

7 14.8 267 9.5 13.8 257 27.7

8 14.5 279 8.9 13.8 270 26.4

9 14.5 295 8.5 14.7 285 26.6

10 14.5 304 8.2 13.4 295 23.4

11 14.4 321 7.7 13.1 311 21.8

12 13.9 330 7.2 12.7 320 20.5

13 14.1 338 7.2 14.5 324 23.1

17 13.4 373 6.2 13.0 363 18.5

21 14.1 395 6.1 13.3 386 17.8

25 14.4 418 5.9 13.5 407 17.1

29 14.7 437 5.8 14.0 424 17.0

33 14.9 449 5.7 13.9 437 16.4

37 14.0 462 5.2 13.6 447 15.7

41 13.2 469 4.8 12.2 454 13.9

45 14.0 477 5.0 13.2 461 14.8

49 13.8 486 4.9 12.8 468 14.1

53 14.9 490 5.2 14.0 475 15.2

57 14.7 496 5.1 13.8 479 14.9

61 14.5 503 5.0 13.4 485 14.3

65 14.1 504 4.8 13.4 484 14.3

69 14.0 503 4.8 12.9 484 13.8

73 13.8 501 4.7 12.7 483 13.6

77 13.7 508 4.6 12.5 487 13.3

81 13.4 507 4.5 12.3 483 13.2

85 13.5 506 4.6 12.3 473 13.4

89 13.1 502 4.5 12.3 478 13.3

93 14.1 500 4.9 13.4 474 14.6

97 14.1 500 4.9 11.7 459 13.2

101 14.1 500 4.9 12.0 455 13.6

Mean for weeks

1-13 15.0 252 11.4 13.9 243 32.2

14-52 14.1 441 5.5 13.3 427 16.1

53-101 14.0 502 4.8 12.8 477 13.9

a Grams of drinking water consumed per animal per day

b Milligrams of sodium dichromate dihydrate consumed per kilogram body weight per day

### 172



### T ab le 

### G2

Water and Compound Consumption by Female Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

Weeks 0 mg/L 14.3 mg/L 57.3 mg/L

on Water Body Water Body Dose Water Body Dose

Study (g/day) a 

### Weight (g/day) Weight (mg/kg) b 

### (g/day) Weight (mg/kg)

(g) (g) (g)

1 13.5 100 13.3 99 1.9 13.5 100 7.8

2 13.3 122 13.0 120 1.6 12.8 121 6.1

3 14.2 135 13.7 132 1.5 13.6 134 5.8

4 13.7 150 13.2 146 1.3 13.1 147 5.1

5 13.5 157 13.3 154 1.2 12.6 154 4.7

6 12.9 164 13.1 161 1.2 12.5 162 4.4

7 12.8 170 12.9 168 1.1 12.1 167 4.1

8 13.0 175 13.0 172 1.1 12.0 172 4.0

9 12.8 180 12.6 178 1.0 12.4 177 4.0

10 12.8 183 12.4 180 1.0 11.7 180 3.7

11 12.7 188 12.3 184 1.0 12.1 185 3.8

12 13.0 193 12.5 189 0.9 11.4 188 3.5

13 12.3 198 11.5 193 0.9 10.9 192 3.2

17 12.1 208 11.4 203 0.8 10.7 202 3.0

21 12.2 217 11.9 211 0.8 11.2 209 3.1

25 11.6 229 11.6 223 0.7 11.2 221 2.9

29 12.1 237 11.6 229 0.7 11.8 229 2.9

33 12.8 246 12.9 239 0.8 12.3 237 3.0

37 12.3 255 12.0 248 0.7 11.7 246 2.7

41 10.8 263 10.7 255 0.6 10.6 253 2.4

45 12.1 272 11.8 261 0.6 11.6 262 2.5

49 12.3 281 11.8 271 0.6 11.1 271 2.3

53 12.1 289 12.1 279 0.6 11.5 278 2.4

57 12.6 297 12.6 288 0.6 12.2 287 2.4

61 12.6 309 12.2 297 0.6 11.8 297 2.3

65 12.4 314 12.2 302 0.6 12.2 304 2.3

69 12.5 317 11.9 307 0.6 11.9 310 2.2

73 12.4 323 12.5 312 0.6 11.6 315 2.1

77 13.4 332 12.3 323 0.5 11.4 320 2.0

81 12.8 337 12.0 328 0.5 12.0 325 2.1

85 12.5 341 12.5 332 0.5 11.8 333 2.0

89 13.4 334 11.9 333 0.5 12.6 333 2.2

93 15.1 348 13.3 333 0.6 12.6 340 2.1

97 13.9 350 13.7 339 0.6 12.9 346 2.1

101 15.0 351 14.4 338 0.6 12.7 346 2.1

Mean for weeks

1-13 13.1 163 12.8 160 1.2 12.4 160 4.6

14-52 12.0 245 11.7 238 0.7 11.4 237 2.8

53-101 13.1 326 12.6 316 0.6 12.1 318 2.2 

### Sodium Dichromate Dihydrate, NTP TR 546

### Sodium Dichromate Dihydrate, NTP TR 546 173



### T ab le 

### G2

Water and Compound Consumption by Female Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

Weeks 172 mg/L 516 mg/L

on Water Body Dose Water Body Dose

Study (g/day) Weight (mg/kg) (g/day) Weight (mg/kg)

(g) (g)

1 10.7 99 18.5 9.6 99 50.2

2 10.9 119 15.8 9.4 115 42.3

3 11.2 131 14.7 10.5 129 42.1

4 11.0 145 13.1 10.0 144 35.9

5 10.8 153 12.2 10.0 152 33.9

6 11.3 161 12.1 9.4 159 30.5

7 10.4 166 10.8 9.5 165 29.7

8 10.0 171 10.1 9.3 170 28.3

9 10.0 175 9.8 9.5 175 28.1

10 10.0 178 9.7 9.2 178 26.7

11 10.0 183 9.4 8.8 182 25.0

12 9.8 186 9.0 8.9 186 24.8

13 9.6 192 8.6 8.4 190 22.8

17 9.6 201 8.2 9.0 199 23.3

21 9.9 206 8.3 9.0 207 22.4

25 9.8 218 7.7 8.9 215 21.3

29 9.7 226 7.4 9.1 222 21.1

33 11.0 235 8.1 9.3 230 20.9

37 10.2 242 7.2 9.2 237 20.1

41 9.5 248 6.6 8.6 242 18.3

45 10.3 256 6.9 9.1 248 19.0

49 10.3 265 6.7 9.3 254 18.9

53 10.7 272 6.8 9.4 263 18.4

57 11.1 279 6.9 9.8 268 18.8

61 11.1 290 6.6 9.4 275 17.7

65 10.6 296 6.2 9.4 281 17.3

69 10.6 302 6.0 9.4 284 17.1

73 11.0 308 6.1 9.5 287 17.1

77 12.1 318 6.5 9.6 298 16.6

81 10.4 319 5.6 8.8 300 15.2

85 10.6 323 5.7 9.9 307 16.6

89 11.0 324 5.8 9.8 314 16.1

93 11.5 328 6.0 10.0 315 16.4

97 11.6 337 5.9 9.7 318 15.7

101 11.5 340 5.8 9.8 312 16.2

Mean for weeks

1-13 10.4 158 11.8 9.4 157 32.3

14-52 10.0 233 7.5 9.1 228 20.6

53-101 11.1 310 6.1 9.6 294 16.9

a Grams of drinking water consumed per animal per day

b Milligrams of sodium dichromate dihydrate consumed per kilogram body weight per day

### 174



### T ab le 

### G3

Water and Compound Consumption by Male Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

Weeks 0 mg/L 14.3 mg/L 28.6 mg/L

on Water Body Water Body Dose Water Body Dose

Study (g/day) a 

### Weight (g/day) Weight (mg/kg) b 

### (g/day) Weight (mg/kg)

(g) (g) (g)

1 3.9 23.2 4.0 23.2 3 4.3 23.5 5

2 4.0 25.3 3.9 25.3 2 4.0 25.7 5

3 3.8 26.8 3.9 26.9 2 3.8 27.1 4

4 3.8 28.0 3.7 28.2 2 3.9 28.5 4

5 3.9 29.9 4.0 30.0 2 3.8 30.3 4

6 3.7 31.5 3.7 31.5 2 3.8 31.9 3

7 3.7 32.9 3.8 33.0 2 3.7 33.4 3

8 3.6 34.2 3.6 34.5 2 3.6 34.8 3

9 3.5 35.9 3.5 36.3 1 3.6 36.6 3

10 3.3 37.5 3.4 37.8 1 3.4 38.2 3

11 3.4 38.9 3.4 39.4 1 3.4 39.9 2

12 3.3 40.2 3.5 40.6 1 3.4 41.2 2

13 3.3 41.7 3.4 41.8 1 3.5 42.4 2

17 3.1 46.7 3.3 46.5 1 3.3 47.2 2

21 3.4 48.9 3.6 48.7 1 3.6 49.2 2

25 3.7 50.1 3.8 49.9 1 3.9 50.2 2

29 3.9 51.4 4.3 51.8 1 4.1 51.8 2

33 3.9 52.2 4.1 52.6 1 4.2 52.5 2

37 4.0 52.7 4.2 52.7 1 4.6 52.7 3

41 4.2 53.8 4.4 53.8 1 4.6 53.7 3

45 4.2 53.8 4.4 53.6 1 4.7 53.9 3

49 4.2 54.5 4.6 54.6 1 4.6 54.7 2

53 4.4 55.2 4.4 55.0 1 4.6 55.0 2

57 4.3 55.5 4.7 55.2 1 4.7 55.2 2

61 4.9 55.1 4.9 54.9 1 5.0 54.1 3

65 4.8 55.3 4.8 55.0 1 4.8 54.4 3

69 5.4 55.6 5.2 55.2 1 5.0 54.2 3

73 5.1 55.1 5.1 53.7 1 5.1 53.6 3

77 5.0 54.0 4.9 52.6 1 5.0 52.9 3

81 4.9 54.3 5.0 52.5 1 4.9 53.1 3

85 4.7 53.0 4.7 52.1 1 4.6 52.3 3

89 4.6 52.0 4.5 51.6 1 4.6 50.7 3

93 4.7 51.7 4.6 50.0 1 4.8 49.3 3

97 4.7 51.7 4.9 50.5 1 5.1 48.8 3

101 4.5 50.3 5.0 49.9 1 4.9 46.9 3

Mean for weeks

1-13 3.6 32.8 3.7 33.0 2 3.7 33.3 3

14-52 3.8 51.6 4.1 51.6 1 4.2 51.8 2

53-101 4.8 53.8 4.8 52.9 1 4.9 52.3 3 

### Sodium Dichromate Dihydrate, NTP TR 546

### Sodium Dichromate Dihydrate, NTP TR 546 175



### T ab le 

### G3

Water and Compound Consumption by Male Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

Weeks 85.7 mg/L 257.4 mg/L

on Water Body Dose Water Body Dose

Study (g/day) Weight (mg/kg) (g/day) Weight (mg/kg)

(g) (g)

1 3.7 23.2 14 2.7 23.2 30

2 3.5 25.2 12 2.7 24.4 29

3 3.5 26.6 11 2.5 25.4 25

4 3.5 27.8 11 2.5 26.3 25

5 3.5 29.5 10 2.6 27.5 24

6 3.5 31.0 10 2.6 28.6 23

7 3.6 32.1 10 2.5 29.5 22

8 3.5 33.6 9 2.5 30.4 21

9 3.5 35.0 9 2.4 31.4 20

10 3.3 36.5 8 2.5 32.2 20

11 3.3 37.9 8 2.4 33.3 19

12 3.2 39.1 7 2.5 34.4 19

13 3.1 40.4 7 2.4 35.2 18

17 3.1 45.1 6 2.4 38.9 16

21 3.4 47.9 6 2.7 42.2 17

25 3.3 49.5 6 2.5 44.5 15

29 3.7 51.6 6 2.7 47.4 15

33 3.7 51.8 6 2.5 48.3 13

37 3.8 52.4 6 2.7 48.9 14

41 3.9 53.3 6 2.7 49.7 14

45 3.9 53.5 6 2.6 49.9 13

49 4.0 54.4 6 2.7 50.4 14

53 3.9 54.4 6 2.7 50.8 14

57 4.0 55.0 6 2.8 50.9 14

61 4.1 54.6 6 2.8 50.8 14

65 4.2 55.1 7 2.9 50.8 15

69 4.3 55.1 7 3.1 50.9 16

73 4.4 54.4 7 3.1 50.3 16

77 4.2 53.8 7 3.3 49.9 17

81 4.2 52.8 7 3.2 49.8 17

85 3.9 52.1 6 3.3 48.8 17

89 3.8 51.3 6 3.1 49.3 16

93 4.1 49.0 7 3.1 49.3 16

97 4.3 48.6 8 3.3 48.1 18

101 4.3 48.4 8 3.5 47.2 19

Mean for weeks

1-13 3.4 32.1 10 2.5 29.4 23

14-52 3.6 51.1 6 2.6 46.7 15

53-101 4.1 52.7 7 3.1 49.8 16

a Grams of drinking water consumed per animal per day

b Milligrams of sodium dichromate dihydrate consumed per kilogram body weight per day

### 176



### T ab le 

### G4

Water and Compound Consumption by Female Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

Weeks 0 mg/L 14.3 mg/L 57.3 mg/L

on Water Body Water Body Dose Water Body Dose

Study (g/day) a 

### Weight (g/day) Weight (mg/kg) b 

### (g/day) Weight (mg/kg)

(g) (g) (g)

1 2.9 17.8 2.9 17.5 2 2.8 17.4 9

2 3.0 19.2 3.0 19.2 2 2.8 19.0 8

3 3.2 20.6 3.1 20.6 2 2.8 20.3 8

4 3.1 21.3 3.2 21.4 2 2.9 21.0 8

5 3.3 22.5 3.2 22.3 2 3.0 21.8 8

6 3.1 23.2 3.2 23.2 2 2.9 22.7 7

7 3.5 24.4 3.3 24.4 2 3.0 23.8 7

8 3.1 26.0 3.2 25.4 2 3.1 24.8 7

9 3.2 26.9 3.3 26.4 2 3.2 25.4 7

10 3.1 27.9 3.3 27.4 2 2.9 26.2 6

11 3.1 28.9 3.3 28.3 2 3.3 27.1 7

12 3.2 30.3 3.3 29.7 2 3.4 28.6 7

13 3.1 31.2 3.1 31.0 1 3.0 29.7 6

17 2.8 37.0 3.0 36.9 1 3.0 34.4 5

21 2.6 41.5 2.6 41.3 1 2.6 38.5 4

25 2.3 44.8 2.5 44.9 1 2.8 41.9 4

29 2.6 48.7 2.5 48.2 1 2.6 46.5 3

33 2.6 51.6 2.5 51.7 1 2.5 48.8 3

37 2.5 53.3 2.8 53.6 1 2.5 50.6 3

41 2.8 55.2 2.8 55.6 1 2.3 52.5 3

45 2.4 59.0 2.5 57.9 1 2.3 55.1 2

49 2.7 59.8 2.7 59.0 1 2.8 56.7 3

53 2.6 62.1 2.5 62.1 1 2.3 60.0 2

57 2.6 61.5 2.6 60.9 1 2.4 59.0 2

61 2.5 62.2 2.5 62.5 1 2.4 60.1 2

65 2.6 63.1 2.6 62.8 1 2.4 61.6 2

69 2.6 64.3 2.6 64.8 1 2.4 62.7 2

73 2.9 63.9 2.7 65.0 1 2.4 62.4 2

77 2.5 62.7 2.4 64.0 1 2.2 61.6 2

81 2.9 61.8 2.6 62.9 1 2.3 60.8 2

85 2.4 61.3 2.5 62.7 1 2.7 59.8 3

89 2.7 60.3 2.7 62.1 1 2.3 59.7 2

93 2.9 60.6 3.0 61.1 1 2.4 58.5 2

97 3.5 59.1 3.5 60.2 1 2.7 58.1 3

101 3.1 60.6 3.6 60.7 1 2.6 58.1 3

Mean for weeks

1-13 3.1 24.6 3.2 24.4 2 3.0 23.7 7

14-52 2.6 50.1 2.7 49.9 1 2.6 47.2 3

53-101 2.8 61.8 2.8 62.4 1 2.4 60.2 2 

### Sodium Dichromate Dihydrate, NTP TR 546

### Sodium Dichromate Dihydrate, NTP TR 546 177



### T ab le 

### G4

Water and Compound Consumption by Female Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate

Weeks 172 mg/L 516 mg/L

on Water Body Dose Water Body Dose

Study (g/day) Weight (mg/kg) (g/day) Weight (mg/kg)

(g) (g)

1 2.5 17.7 24 1.6 17.5 47

2 2.2 19.1 20 1.7 18.4 48

3 2.2 20.2 19 1.6 19.3 43

4 2.2 20.8 18 1.8 19.9 47

5 2.6 21.5 21 1.7 20.8 42

6 2.3 22.4 18 1.7 21.3 41

7 2.8 23.1 21 2.0 22.3 46

8 2.6 23.9 19 1.9 23.3 42

9 2.4 24.6 17 1.9 23.8 41

10 2.5 25.2 17 1.9 24.6 40

11 2.4 25.8 16 1.9 24.7 40

12 2.5 26.8 16 1.9 25.5 39

13 2.5 27.5 16 1.9 26.2 37

17 2.3 31.4 13 1.9 28.6 34

21 3.0 35.1 15 1.9 30.8 32

25 2.2 37.6 10 1.8 32.8 28

29 2.4 41.5 10 1.9 36.0 27

33 2.2 43.7 9 2.0 37.5 28

37 2.2 45.5 8 1.9 38.9 25

41 2.3 47.8 8 2.0 41.0 25

45 2.1 50.4 7 1.8 43.9 21

49 2.3 52.7 8 1.9 45.4 22

53 2.0 55.4 6 1.9 48.1 20

57 2.1 55.8 7 1.9 48.4 20

61 2.1 57.1 6 1.9 49.2 20

65 2.1 57.7 6 1.9 50.0 20

69 2.0 59.1 6 2.0 51.9 20

73 2.0 58.4 6 1.8 51.9 18

77 1.9 57.7 6 2.0 51.9 20

81 2.1 57.6 6 1.8 51.8 18

85 2.0 57.1 6 1.7 51.2 17

89 2.0 57.5 6 1.8 51.6 18

93 2.0 56.0 6 1.9 50.3 20

97 2.4 56.1 7 2.2 50.8 22

101 2.2 55.8 7 2.0 51.4 20

Mean for weeks

1-13 2.4 23.0 19 1.8 22.1 43

14-52 2.3 42.9 10 1.9 37.2 27

53-101 2.1 57.0 6 1.9 50.7 19

a Grams of drinking water consumed per animal per day

b Milligrams of sodium dichromate dihydrate consumed per kilogram body weight per day

### 178 Sodium Dichromate Dihydrate, NTP TR 546

### 179



# APPENDIX H

INGREDIENTS, NUTRIENT COMPOSITION,

AND CONTAMINANT LEVELS

IN NTP-2000 RAT AND MOUSE RATION

T ab le 

### H1 Ingredients of NTP-2000 Rat and Mouse Ration

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180

T ab le 

### H2 Vitamins and Minerals in NTP-2000 Rat and Mouse Ration

. . . . . . . . . . . . . . . . . . . . . . . . . 180

T ab le 

### H3 Nutrient Composition of NTP-2000 Rat and Mouse Ration

. . . . . . . . . . . . . . . . . . . . . . . . . . 181

T ab le 

### H4 Contaminant Levels in NTP-2000 Rat and Mouse Ration

. . . . . . . . . . . . . . . . . . . . . . . . . . . 182

### 180



### T ab le 

### H1

Ingredients of NTP-2000 Rat and Mouse Ration

Ingredients Percent by Weight

Ground hard winter wheat 22.26

Ground #2 yellow shelled corn 22.18

Wheat middlings 15.0

Oat hulls 8.5

Alfalfa meal (dehydrated, 17% protein) 7.5

Purified cellulose 5.5

Soybean meal (49% protein) 5.0

Fish meal (60% protein) 4.0

Corn oil (without preservatives) 3.0

Soy oil (without preservatives) 3.0

Dried brewer’s yeast 1.0

Calcium carbonate (USP) 0.9

Vitamin premix a 0.5

Mineral premix b 0.5

Calcium phosphate, dibasic (USP) 0.4

Sodium chloride 0.3

Choline chloride (70% choline) 0.26

Methionine 0.2

a Wheat middlings as carrier

b Calcium carbonate as carrier



### T ab le 

### H2

Vitamins and Minerals in NTP-2000 Rat and Mouse Ration a



### Amount Source

Vitamins

A 4,000 IU Stabilized vitamin A palmitate or acetate

D 1,000 IU D-activated animal sterol

K 1.0 mg Menadione sodium bisulfite complex



### “ -Tocopheryl acetate 100 IU

Niacin 23 mg

Folic acid 1.1 mg

d

-Pantothenic acid 10 mg d -Calcium pantothenate

Riboflavin 3.3 mg

Thiamine 4 mg Thiamine mononitrate

B

12 52 μg

Pyridoxine 6.3 mg Pyridoxine hydrochloride

Biotin 0.2 mg d -Biotin



### Minerals

Magnesium 514 mg Magnesium oxide

Iron 35 mg Iron sulfate

Zinc 12 mg Zinc oxide

Manganese 10 mg Manganese oxide

Copper 2.0 mg Copper sulfate

Iodine 0.2 mg Calcium iodate

Chromium 0.2 mg Chromium acetate

a Per kg of finished product 

### Sodium Dichromate Dihydrate, NTP TR 546

### Sodium Dichromate Dihydrate, NTP TR 546 181



### T ab le 

### H3

Nutrient Composition of NTP-2000 Rat and Mouse Ration

Mean ± Standard

Nutrient Deviation Range Number of Samples

Protein (% by weight) 14.8 ± 0.45 13.8 – 15.8 26

Crude fat (% by weight) 8.1 ± 0.35 7.4 – 9.0 26

Crude fiber (% by weight) 9.1 ± 0.45 8.2 – 9.9 26

Ash (% by weight) 5.0 ± 0.24 4.4 – 5.6 26



### Amino Acids (% of total diet)

Arginine 0.750 ± 0.048 0.670 – 0.850 15

Cystine 0.225 ± 0.025 0.150 – 0.250 15

Glycine 0.701 ± 0.039 0.620 – 0.750 15

Histidine 0.365 ± 0.090 0.310 – 0.680 15

Isoleucine 0.533 ± 0.038 0.430 – 0.590 15

Leucine 1.077 ± 0.059 0.960 – 1.150 15

Lysine 0.703 ± 0.125 0.310 – 0.830 15

Methionine 0.402 ± 0.049 0.260 – 0.460 15

Phenylalanine 0.615 ± 0.035 0.540 – 0.660 15

Threonine 0.492 ± 0.040 0.430 – 0.590 15

Tryptophan 0.135 ± 0.018 0.110 – 0.160 15

Tyrosine 0.378 ± 0.048 0.280 – 0.460 15

Valine 0.658 ± 0.043 0.550 – 0.710 15



### Essential Fatty Acids (% of total diet)

Linoleic 3.90 ± 0.256 3.49 – 4.54 15

Linolenic 0.30 ± 0.035 0.21 – 0.35 15



### Vitamins

Vitamin A (IU/kg) 5,031 ± 115 3,400 – 8,900 26

Vitamin D (IU/kg) 1,000 a



### “ -Tocopherol (ppm) 84.2 ± 16.60 52.0 – 110.0 15

Thiamine (ppm) b 8.7 ± 3.58 5.9 – 25.2 26

Riboflavin (ppm) 6.8 ± 2.11 4.20 – 11.20 15

Niacin (ppm) 79.0 ± 10.50 66.4 – 98.2 15

Pantothenic acid (ppm) 23.9 ± 3.73 17.4 – 29.8 15

Pyridoxine (ppm) b 9.21 ± 2.20 6.4 – 13.7 15

Folic acid (ppm) 1.75 ± 0.54 1.20 – 3.27 15

Biotin (ppm) 0.332 ± 0.12 0.225 – 0.704 15

Vitamin B

12 (ppb) 60.5 ± 46.5 18.3 – 174.0 15

Choline (ppm) b 3,064 ± 270 2,700 – 3,790 15



### Minerals

Calcium (%) 0.964 ± 0.047 0.873 – 1.050 26

Phosphorus (%) 0.585 ± 0.027 0.538 – 0.641 26

Potassium (%) 0.665 ± 0.023 0.626 – 0.694 15

Chloride (%) 0.376 ± 0.041 0.300 – 0.474 15

Sodium (%) 0.191 ± 0.017 0.160 – 0.222 15

Magnesium (%) 0.201 ± 0.009 0.185 – 0.217 15

Sulfur (%) 0.170 ± 0.029 0.116 – 0.209 15

Iron (ppm) 182 ± 46.7 135 – 311 15

Manganese (ppm) 54.1 ± 7.89 42.1 – 73.1 15

Zinc (ppm) 55.0 ± 9.55 43.3 – 78.5 15

Copper (ppm) 6.65 ± 1.790 3.21 – 10.50 15

Iodine (ppm) 0.512 ± 0.221 0.233 – 0.972 15

Chromium (ppm) 0.604 ± 0.253 0.330 – 1.380 14

Cobalt (ppm) 0.25 ± 0.074 0.20 – 0.47 14

a From formulation

b As hydrochloride (thiamine and pyridoxine) or chloride (choline)

### 182



### T ab le 

### H4

Contaminant Levels in NTP-2000 Rat and Mouse Ration a



### Mean ± Standard

Deviation b 

### Range Number of Samples

Contaminants

Arsenic (ppm) 0.38 ± 0.158 0.14 – 0.50 26

Cadmium (ppm) 0.07 ± 0.022 0.04 – 0.10 26

Lead (ppm) 0.08 ± 0.031 0.05 – 0.17 26

Mercury (ppm) <0.02 26

Selenium (ppm) 0.19 ± 0.027 0.14 – 0.23 26

Aflatoxins (ppb) <5.00 26

Nitrate nitrogen (ppm) c 15.2 ± 4.09 10.0 – 24.4 26

Nitrite nitrogen (ppm) c <0.61 26

BHA (ppm) d <1.0 26

BHT (ppm) d <1.0 26

Aerobic plate count (CFU/g) 25 ± 68 10 – 360 26

Coliform (MPN/g) 0.3 ± 0.0 3.0 – 3.0 26

Escherichia coli (MPN/g) <10 26

Salmonella (MPN/g) Negative 26

Total nitrosoamines (ppb) e 4.3 ± 1.93 2.3 – 8.5 26

N

-Nitrosodimethylamine (ppb) e 2.6 ± 1.68 1.1 – 6.9 26

N

-Nitrosopyrrolidine (ppb) e 1.7 ± 0.74 0.9 – 4.1 26



### Pesticides (ppm)



### “ -BHC <0.01 26



### $ -BHC <0.02 26



### ( -BHC <0.01 26



### * -BHC <0.01 26

Heptachlor <0.01 26

Aldrin <0.01 26

Heptachlor epoxide <0.01 26

DDE <0.01 26

DDD <0.01 26

DDT <0.01 26

HCB <0.01 26

Mirex <0.01 26

Methoxychlor <0.05 26

Dieldrin <0.01 26

Endrin <0.01 26

Telodrin <0.01 26

Chlordane <0.05 26

Toxaphene <0.10 26

Estimated PCBs <0.20 26

Ronnel <0.01 26

Ethion <0.02 26

Trithion <0.05 26

Diazinon <0.10 26

Methyl chlorpyrifos 0.082 ± 0.069 0.020 – 0.259 26

Methyl parathion <0.02 26

Ethyl parathion <0.02 26

Malathion 0.284 ± 0.477 0.020 – 1.850 26

Endosulfan I <0.01 26

Endosulfan II <0.01 26

Endosulfan sulfate <0.03 26

a All samples were irradiated. CFU=colony-forming units; MPN=most probable number; BHC=hexachlorocyclohexane or

benzene hexachloride

b For values less than the limit of detection, the detection limit is given as the mean.

c Sources of contamination: alfalfa, grains, and fish meal

d Sources of contamination: soy oil and fish meal

e All values were corrected for percent recovery. 

### Sodium Dichromate Dihydrate, NTP TR 546

### 183



# APPENDIX I

SENTINEL ANIMAL PROGRAM

M et h od s



### . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184

T ab le 

### I 1 Murine Virus Antibody Determinations for Rats and Mice

in the 2-Year Drinking Water Studies of Sodium Dichromate Dihydrate

. . . . . . . . . . . . . . 185

### 184



# SENTINEL ANIMAL PROGRAM

M et h od s

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.

During the 2-year study, serum samples were collected from five or six male and five female sentinel rats and mice

at 6, 12, and 18 months; from five male and five female rats and five female mice in the 516 mg/L group at study

termination; and from five male mice in the 257.4 mg/L group at study termination. In addition, serum samples

were collected from six male and five female treated rats at 19 months, and fecal samples were collected from

five male and five female mice at 18 months. Blood from each animal was collected and allowed to clot, and the

serum was separated. The samples were processed appropriately and sent to BioReliance Corporation (Rockville,

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 Time of Analysis



# Rats

ELISA

Mycoplasma arthritidis Study termination

Mycoplasma pulmonis Study termination

PVM (pneumonia virus of mice) 6, 12, and 18 months, study termination

RCV/SDA

(rat coronavirus/sialodacryoadenitis virus) 6, 12, and 18 months, study termination

Sendai 6, 12, 18, and 19 months, study termination

Immunofluorescence Assay

Parvovirus 6, 12, and 18 months, study termination

Sendai 18 and 19 months

Western Blot

Sendai 18 months Sodium Dichromate Dihydrate, NTP TR 546

### Sodium Dichromate Dihydrate, NTP TR 546 185



### Method and Test Time of Analysis



# Mice

ELISA

Ectromelia virus 6, 12, and 18 months, study termination

EDIM (epizootic diarrhea of infant mice) 6, 12, and 18 months, study termination

GDVII (mouse encephalomyelitis virus) 6, 12, and 18 months, study termination

LCM (lymphocytic choriomeningitis virus) 6, 12, and 18 months, study termination

MMV (mouse minute virus) Study termination

Mouse adenoma virus-FL 6, 12, and 18 months, study termination

MHV (mouse hepatitis virus) 6, 12, and 18 months, study termination

M. arthritidis Study termination

M. pulmonis Study termination

Parvovirus Study termination

PVM 6, 12, and 18 months, study termination

Reovirus 3 6, 12, and 18 months, study termination

Sendai 6, 12, and 18 months, study termination

Immunofluorescence Assay

EDIM 12 months

Helicobacter bilis 18 months

Helicobacter hepaticus 18 months

MCMV (mouse cytomegalovirus) Study termination

Parvovirus 6, 12, and 18 months

PVM 18 months and study termination

Results of serology tests are presented in Table I1.

T ab le 

### I 1

Murine Virus Antibody Determinations for Rats and Mice in the 2-Year Drinking Water Studies

of Sodium Dichromate Dihydrate

Incidence of Antibody Positive Serologic

Interval in Sentinel Animals Reaction for

Rats

6 Months 0/10 None positive

12 Months 0/10 None positive

18 Months 1/11 a Sendai

19 Months 0/11 None positive

Study termination 0/10 None positive



### Mice

6 Months 0/10 None positive

12 Months 0/10 None positive

18 Months 0/10 None positive

Study termination 0/10 None positive

a Based on retesting of serum samples at 19 months, this most likely represents a false positive result in one rat. There was no evidence of

infection by a viral organism in these animals.

### 186 Sodium Dichromate Dihydrate, NTP TR 546

### 187



# APPENDIX J

CHROMIUM TISSUE DISTRIBUTION STUDY

M a te r i a l s a nd 

### M et h od s



### . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188

T ab le 

### J1 Tissue Concentrations and Excreta Content of Chromium in Male Rats

in the 2-Year Drinking Water Study of Sodium Dichromate Dihydrate

. . . . . . . . . . . . . . . 190

T ab le 

### J2 Tissue Concentrations and Excreta Content of Chromium in Female Mice

in the 2-Year Drinking Water Study of Sodium Dichromate Dihydrate

. . . . . . . . . . . . . . . 191

### 188 Sodium Dichromate Dihydrate, NTP TR 546



# CHROMIUM TISSUE DISTRIBUTION STUDY

M a te r i a l s a nd 

# M et h od s

Groups of 40 special study male rats and female mice were randomly assigned to the tissue distribution study at

the beginning of the 2

- year study and treated identically to the core study groups. On days 4, 11, 180, and 369,

up to 10 animals per exposure group were removed from treatment and placed in individual metabolism cages

to allow separate collection of urine and feces. The animals had access to undosed water and feed ad libitum

. Two collections of urine and feces were made to include the intervals from 0 to 24 and 24 to 48 hours; measured

values were combined to yield the reported 48-hour values. Urine and feces collections were frozen at –20° C and

shipped to the analytical laboratory (RTI International, Research Triangle Park, NC).

At the end of 48 hours, the animals were anesthetized with CO

2 

### /O

2 

### , and blood was taken from the retroorbital

sinus into heparinized centrifuge tubes. The blood was separated into cells and plasma. While the animals were

still under CO

2 

### /O

2 

### anesthesia, the abdominal wall was opened and the aorta was severed. The entire liver, both

kidneys, and the stomach (separated into glandular and forestomach parts) were removed, weighed, and frozen at

–20° C and shipped frozen to the analytical laboratory. Stainless steel was avoided during the tissue collection;

only plastic, TeflonTM, ceramic, or tungsten carbide instruments were used.

The tissue samples were stored in a freezer. Prior to homogenization, the samples were allowed to thaw at room

temperature in a Class 100 environment. Tissue samples were added to tared glass scintillation vials, and the

whole wet tissue mass was recorded. A minimal amount of deionized water was added to each sample, and the

total mass (tissue plus deionized water) was recorded. Each tissue sample was homogenized using a Polytron

tissue homogenizer (Brinkmann Instruments, Westbury, NY) and returned to frozen storage.

Prior to aliquot transfer, the tissue homogenate was removed from frozen storage and allowed to thaw at

room temperature in a Class 100 environment. Each tissue homogenate was mixed well to ensure complete

homogeneity. An aliquot of homogenate containing approximately 0.500 g of tissue was transferred to a tared

50 mL centrifuge tube, and the mass was recorded. Approximately 5% of the rat kidney samples were prepared

with duplicate aliquots, and masses were recorded. The actual mass for each sample was calculated by applying

the percent tissue in the homogenate to the measured mass. Homogenization was not necessary if the tissue mass

was less than 0.500 g, but duplicate aliquots for these samples could not be prepared.

Five mL of concentrated nitric acid was added to each centrifuge tube containing tissue. The tubes were capped

with microwavable caps and allowed to stand overnight at room temperature. The following morning, 2 mL of

deionized water was added to each centrifuge tube. The tubes were arranged in a microwave tray; the thermowell

and temperature sensors were inserted into one of the sample tubes to monitor the digestion; and the samples were

subjected to a four

- stage microwave digestion program that ramped the power from 60% to 100% with hold times

of 5 to 20 minutes. Samples achieved a maximum temperature of 110° C, which was held for 10 minutes.

After the digestion was complete, the samples were allowed to cool to room temperature. To each tube, 0.500 mL

of hydrogen peroxide and 0.125 mL of hydrofluoric acid were added as was more deionized water, if necessary,

to avoid charring. The samples were subjected to the same microwave program a second time and then allowed

to cool. The content of each tube was transferred to a 25 mL volumetric flask, and 0.250 mL of a previously

prepared 1.00 μg/mL internal standard solution was added. The internal standard solution was prepared by

transferring 100 μL aliquots of NIST-traceable yttrium, bismuth, indium, and scandium stock solutions (1,000 μg/

mL) to a 100 mL volumetric flask, adding 1 mL of concentrated nitric acid, and diluting to volume with deionized

water. The tubes were rinsed with deionized water, and the rinses were added to the flasks. Each flask was

brought to volume with deionized water and mixed well. Samples were transferred to clean plastic storage bottles

and stored in a refrigerator until the day of analysis.

The solvent standards, digested matrix standards, and experimental samples were analyzed by inductively coupled

### Sodium Dichromate Dihydrate, NTP TR 546 189



### plasma-mass spectrometry using a Thermo X7 instrument (ThermoElectron Corp., Winsford, Cheshire, U.K.) or

a Plasma Quad XR Instrument (VG Elemental Ltd., Winsford, Cheshire, U.K.) with a concentric nebulizer and a

Peltier impact

- bead spray chamber cooled to 5° C. A calibration curve was constructed at the beginning of each

analysis, and the performance of the calibration was evaluated prior to sample analysis. A successful calibration

was indicated by an acceptable correlation coefficient ( r > 0.99) and residual percent read

- backs within 20% of

the lowest standard and within 10% of all other solvent standards. A valid calibration included a minimum of six

calibration standards and a calibration blank.

Analysis data were considered valid if they were bracketed by valid quality control (QC) sets. A maximum of

10 samples (including method blanks and controls) were bracketed by a QC set, which consisted of the calibration

blank and two midlevel calibration standards. A QC set passed when the measured concentration for one midlevel

calibration standard was within 10% of its nominal value. This selected midlevel calibration standard was then

required to pass consistently throughout the analysis. If the selected midlevel calibration standard failed, it was

necessary to reanalyze the bracketed samples. Samples with responses greater than the calibration range were

diluted with diluent solution to get a response within the range. The diluent solution was prepared by adding 1 mL

of the internal standard solution and 20 mL of concentrated nitric acid to a 100 mL plastic volumetric flask and

diluting to volume with deionized water.

### Sodium Dichromate Dihydrate, NTP TR 546 190



### T ab le 

### J1

Tissue Concentrations and Excreta Content of Chromium in Male Rats in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate a



### 0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

n 3 3 3 3 3

Erythrocytes ( μ g/g)

Day 6 0.044 ± 0.002 0.051 ± 0.002 0.126 ± 0.012* 0.252 ± 0.022* 0.391 ± 0.012**

Day 13 0.051 ± 0.002 0.036 ± 0.005 0.203 ± 0.019 0.504 ± 0.066* 0.899 ± 0.134**

Day 182 0.050 ± 0.014 0.054 ± 0.003 0.208 ± 0.002 0.591 ± 0.014* 0.997 ± 0.051**

Day 371 0.055 ± 0.003 0.064 ± 0.006* 0.160 ± 0.059** 0.526 ± 0.031** 0.693 ± 0.029**

Plasma ( μ g/g) b

Day 6 0.052 ± 0.003 0.068 ± 0.007* 0.079 ± 0.003** 0.087 ± 0.008** 0.109 ± 0.007**

Day 13 0.054 ± 0.004 0.048 ± 0.006 0.079 ± 0.005* 0.103 ± 0.008** 0.146 ± 0.008**

Day 182 0.063 ± 0.005 0.064 ± 0.003 0.081 ± 0.004* 0.099 ± 0.007** 0.146 ± 0.009**

Day 371 0.054 ± 0.014 0.062 ± 0.005 0.071 ± 0.011 0.110 ± 0.010** 0.146 ± 0.003**

Liver ( μ g/g)

Day 6 0.072 ± 0.007 0.097 ± 0.015 0.326 ± 0.027* 1.116 ± 0.200** 1.589 ± 0.125**

Day 13 0.080 ± 0.013 0.080 ± 0.005 0.700 ± 0.065 1.899 ± 0.347* 3.239 ± 0.385**

Day 182 0.081 ± 0.004 0.249 ± 0.007* 1.568 ± 0.040** 4.101 ± 0.110** 6.650 ± 0.249**

Day 371 0.092 ± 0.003 0.289 ± 0.029* 1.145 ± 0.334** 4.383 ± 0.419** 7.735 ± 0.155**

Kidney ( μ g/g)

Day 6 0.376 ± 0.070 0.252 ± 0.049 0.591 ± 0.043 1.122 ± 0.087* 1.570 ± 0.024**

Day 13 0.089 ± 0.006 0.225 ± 0.009* 1.125 ± 0.041** 2.556 ± 0.390** 4.409 ± 0.596**

Day 182 0.083 ± 0.003 1.153 ± 0.036* 5.464 ± 0.054** 10.847 ± 0.195** 15.263 ± 0.280**

Day 371 0.170 ± 0.011 1.564 ± 0.055* 4.879 ± 1.259** 13.423 ± 0.307** 18.530 ± 0.430**

Glandular stomach ( μ g/g)

Day 6 0.076 ± 0.003 0.143 ± 0.008* 0.333 ± 0.040** 0.773 ± 0.105** 1.967 ± 0.109**

Day 13 0.095 ± 0.008 0.254 ± 0.073* 0.310 ± 0.049* 1.331 ± 0.060** 1.762 ± 0.042**

Day 182 0.197 ± 0.031 0.414 ± 0.012* 1.043 ± 0.081** 4.300 ± 0.367** 9.886 ± 0.354**

Day 371 0.253 ± 0.066 0.334 ± 0.029 1.038 ± 0.115* 4.801 ± 0.345** 14.643 ± 0.121**

Forestomach ( μ g/g)

Day 6 0.098 ± 0.024 0.076 ± 0.004 0.122 ± 0.008 0.294 ± 0.029 0.285 ± 0.123

Day 13 0.091 ± 0.015 0.102 ± 0.034 0.171 ± 0.050 0.221 ± 0.055* 0.593 ± 0.159**

Day 182 0.089 ± 0.018 0.099 ± 0.003 0.338 ± 0.022* 0.574 ± 0.171* 1.654 ± 0.244**

Day 371 0.090 ± 0.015 0.118 ± 0.008 0.328 ± 0.081* 1.338 ± 0.444** 2.849 ± 0.975**

Feces ( μ g) c,d

Day 6 11.56 ± 3.06 26.87 ± 5.56* 122.29 ± 5.49** 246.86 ± 84.73** 1,030.2 ± 117.71**

Day 13 9.056 ± 1.977 52.335 ± 6.275* 171.734 ± 9.232** 362.994 ± 74.118** 972.867 ± 54.316**

Day 182 10.04 ± 2.06 63.64 ± 6.07* 229.71 ± 17.38** 467.84 ± 33.30** 1,947.6 ± 287.25**

Day 371 6.869 ± 1.126 36.299 ± 4.185* 139.488 ± 11.446* e 311.849 ± 10.293** 1,146.27 ± 114.235**

Urine ( μ g) c,d

Day 6 0.275 ± 0.073 0.480 ± 0.053* 2.520 ± 0.732** 4.594 ± 1.118** 6.967 ± 0.717**

Day 13 0.139 ± 0.028 0.396 ± 0.114* 1.100 ± 0.253** 1.943 ± 0.390** 4.561 ± 0.486**

Day 182 0.630 ± 0.131 1.145 ± 0.101* 7.076 ± 0.075** 12.580 ± 0.898** 20.137 ± 0.579**

Day 371 0.588 ± 0.087 2.023 ± 0.267* 7.406 ± 1.020** 13.702 ± 2.107** 23.969 ± 3.875**

* Significantly different (P # 0.05) from the control group by Shirley’s test

** P # 0.01

a Mean ± standard error. Statistical tests were performed on unrounded data.

b n=6 for all plasma values

c Cumulative chromium content for 48 hours ending on the day indicated

d Measured values less than the experimental limit of quantitation (ELOQ) (2.00 μg Cr/g feces; 0.100 μg Cr/g urine) were included in the analysis

as 1⁄2 ELOQ × sample mass.

e n=2

### 191 Sodium Dichromate Dihydrate, NTP TR 546



### T ab le 

### J2

Tissue Concentrations and Excreta Content of Chromium in Female Mice in the 2-Year Drinking Water Study

of Sodium Dichromate Dihydrate a



### 0 mg/L 14.3 mg/L 57.3 mg/L 172 mg/L 516 mg/L

n 3 3 3 3 3

Erythrocytes ( μ g/g)

Day 6 0.040 ± 0.003 0.056 ± 0.010 0.108 ± 0.009* 0.260 ± 0.047** 0.374 ± 0.078**

Day 13 0.043 ± 0.005 0.042 ± 0.002 0.341 ± 0.100 0.747 ± 0.087* 1.190 ± 0.137**

Day 182 0.058 ± 0.004 0.079 ± 0.008 0.194 ± 0.016* 0.719 ± 0.052** 1.561 ± 0.165**

Day 371 0.036 ± 0.004 0.042 ± 0.011 0.094 ± 0.002 0.340 ± 0.020* 0.795 ± 0.089**

Plasma ( μ g/g) b

Day 6 0.064 ± 0.006 0.075 ± 0.016 0.111 ± 0.026 0.150 ± 0.039** 0.213 ± 0.059**

Day 13 0.034 ± 0.016 0.038 ± 0.018 0.133 ± 0.024** 0.204 ± 0.045** 0.311 ± 0.077**

Day 182 0.051 ± 0.006 0.070 ± 0.010 0.116 ± 0.005** 0.167 ± 0.009** 0.253 ± 0.016**

Day 371 0.065 ± 0.004 0.086 ± 0.010 0.118 ± 0.014** 0.150 ± 0.012** 0.209 ± 0.009**

Liver ( μ g/g)

Day 6 0.098 ± 0.039 0.340 ± 0.010* 1.421 ± 0.146** 4.638 ± 0.950** 5.622 ± 0.795**

Day 13 0.126 ± 0.003 0.591 ± 0.027* 2.659 ± 0.094** 9.374 ± 0.892** 14.830 ± 2.347**

Day 182 0.147 ± 0.015 0.746 ± 0.068* 4.575 ± 0.559** 17.270 ± 2.746** 52.047 ± 2.890**

Day 371 0.069 ± 0.007 0.792 ± 0.019* 3.782 ± 0.143** 13.777 ± 0.951** 39.450 ± 1.655**

Kidney ( μ g/g)

Day 6 0.095 ± 0.011 0.166 ± 0.011* 0.415 ± 0.020** 0.892 ± 0.106** 1.338 ± 0.157**

Day 13 0.127 ± 0.032 0.245 ± 0.003* 1.259 ± 0.051** 4.061 ± 0.718** 4.027 ± 0.286**

Day 182 0.067 ± 0.006 0.361 ± 0.061* 2.062 ± 0.191** 10.187 ± 1.078** 17.487 ± 0.500**

Day 371 0.070 ± 0.002 0.340 ± 0.014* 1.291 ± 0.064** 7.868 ± 0.510** 21.827 ± 2.446**

Glandular stomach ( μ g/g)

Day 6 0.306 ± 0.056 0.645 ± 0.253 1.258 ± 0.290* 2.450 ± 0.266** 5.785 ± 0.131**

Day 13 0.207 ± 0.053 0.324 ± 0.030 2.614 ± 0.190* 7.048 ± 1.751** 13.130 ± 2.604**

Day 182 0.305 ± 0.078 0.644 ± 0.035* 3.659 ± 0.547** 11.520 ± 3.017** 52.673 ± 12.310**

Day 371 0.731 ± 0.306 0.676 ± 0.104 2.807 ± 0.330* 9.994 ± 1.079* 49.867 ± 12.251**

Forestomach ( μ g/g)

Day 6 0.328 ± 0.132 0.683 ± 0.262 1.308 ± 0.553 1.102 ± 0.373 1.286 ± 0.116

Day 13 0.201 ± 0.094 0.288 ± 0.056 0.400 ± 0.044 2.030 ± 0.532* 3.849 ± 1.811*

Day 182 0.173 ± 0.064 0.444 ± 0.099 1.033 ± 0.102* 2.141 ± 0.643** 9.624 ± 3.638**

Day 371 0.320 ± 0.049 0.381 ± 0.077 1.271 ± 0.300* 1.812 ± 0.208* 7.442 ± 0.764**

Feces ( μ g) c,d

Day 6 2.598 ± 0.899 9.364 ± 1.422* 12.869 ± 2.918* 43.632 ± 10.221** 162.588 ± 31.040**

Day 13 2.348 ± 1.173 12.103 ± 3.355* 85.798 ± 21.386** 46.865 ± 4.905* 107.822 ± 30.842**

Day 182 1.275 ± 0.568 5.266 ± 0.425* 17.633 ± 3.070** 24.583 ± 5.796** 122.734 ± 21.606**

Day 371 7.484 ± 2.862 9.502 ± 1.566 18.682 ± 2.165* 40.853 ± 3.288** 72.071 ± 19.116**

Urine ( μ g) c,d

Day 6 0.034 ± 0.007 0.122 ± 0.033* 0.347 ± 0.152* e

— f

— Day 13 0.020 ± 0.008 0.233 ± 0.009 e 0.501 g

— 2.190 ± 0.126* e

Day 182 0.089 ± 0.051 0.145 ± 0.035 e 0.648 ± 0.213* 1.339 ± 0.199* e

— Day 371 0.074 ± 0.008 0.470 ± 0.103* 1.343 ± 0.234** 3.953 ± 1.460** e 3.251 ± 1.263**

* Significantly different (P # 0.05) from the control group by Shirley’s test

** P # 0.01

a Mean ± standard error. Statistical tests were performed on unrounded data.

b n=6 for all plasma values

c Cumulative chromium content for 48 hours ending on the day indicated

d Measured values less than the experimental limit of quantitation (ELOQ) (2.00 μg Cr/g feces; 0.100 μg Cr/g urine) were included in the analysis

as 1⁄2 ELOQ × sample mass.

e n=2

f Data not available

g n=1

### Sodium Dichromate Dihydrate, NTP TR 546 192