NTP TECHNICAL REPORT
 

ON THE 

TOXICOLOGY AND CARCINOGENESIS
 

STUDIES OF
 

60-HZ MAGNETIC FIELDS
 

IN F344/N RATS AND B6C3F1 MICE

(WHOLE-BODY EXPOSURE STUDIES) 

NATIONAL TOXICOLOGY PROGRAM
 

P.O. Box 12233
 

Research Triangle Park, NC 27709
 

April 1999 

NTP TR 488
 

NIH Publication No. 99-3978
 

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES
 

Public Health Service
 

National Institutes of Health
 
FOREWORD 

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

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

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

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

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

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

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

research and to biological assay development and validation. 

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

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

prevention of disease. 

The studies described in this Technical Report were performed under the direction of the NIEHS and were 

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

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

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

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

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

before being presented for public review. 

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

carcinogenic activity, of selected chemicals or physical agents in laboratory animals (usually two species, 

rats and mice). The interpretive conclusions presented in this Technical Report are based only on the results 

of these NTP studies. Extrapolation of these results to other species and quantitative risk analyses for 

humans require wider analyses beyond the purview of these studies. Selection per se is not an indicator of 

carcinogenic potential. 

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

Management, NIEHS, P.O. Box 12233, MD E1-02, Research Triangle Park, NC 27709 (919-541-3419). 

The Abstracts and other study information for 2-year studies are available at the NTP’s World Wide Web 

site: http://ntp-server.niehs.nih.gov. 

 


 


 


 


 


 


 


 


 


 


 


 


 

NTP TECHNICAL REPORT
 

ON THE
 

TOXICOLOGY AND CARCINOGENESIS
 

STUDIES OF
 

60-HZ MAGNETIC FIELDS
 

IN F344/N RATS AND B6C3F1 MICE

(WHOLE-BODY EXPOSURE STUDIES) 

NATIONAL TOXICOLOGY PROGRAM
 

P.O. Box 12233
 

Research Triangle Park, NC 27709
 

April 1999 

NTP TR 488
 

NIH Publication No. 99-3978
 

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES
 

Public Health Service
 

National Institutes of Health
 

 

2 60-Hz Magnetic Fields, NTP TR 488 

CONTRIBUTORS
 

National Toxicology Program 

Evaluated and interpreted results and reported findings 

G.A. Boorman, D.V.M., Ph.D., Study Scientist 

D.A. Bridge, B.S. 

J.R. Bucher, Ph.D. 

R.E. Chapin, Ph.D. 

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

J.K. Haseman, Ph.D. 

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

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

J.H. Roycroft, Ph.D. 

C.S. Smith, Ph.D. 

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

D.B. Walters, Ph.D. 

K.L. Witt, M.S., Integrated Laboratory Systems 

IIT Research Institute 

Conducted studies, evaluated pathology findings 

D.L. McCormick, Ph.D., Principal Investigator 

J.R. Gauger 

T.R. Johnson 

Experimental Pathology Laboratories, Inc. 

Provided pathology quality assurance 

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

S. Botts, M.S., D.V.M., Ph.D. 

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

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

Dynamac Corporation 

Prepared quality assurance audits 

S. Brecher, Ph.D., Principal Investigator 

Analytical Sciences, Inc. 

Provided statistical analyses 

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

S.R. Lloyd, M.S. 

N.G. Mintz, B.S. 

NTP Pathology Working Group 

Evaluated slides, prepared pathology report on rats 

(4 December 1997) 

P.K. Hildebrandt, D.V.M., Chairperson 

PATHCO 

G.A. Boorman, D.V.M., Ph.D. 

National Toxicology Program 

S. Botts, M.S., D.V.M., Ph.D. 

Experimental Pathology Laboratories, Inc. 

J. Everitt, D.V.M. 

Chemical Industry Institute of Toxicology 

R.M. Kovatch, D.V.M. 

Pathology Associates International 

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

Tox Path Inc. 

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

National Toxicology Program 

Evaluated slides, prepared pathology report on mice 

(2 December 1997) 

J.C. Seely, D.V.M., Chairperson 

PATHCO 

G.A. Boorman, D.V.M., Ph.D. 

National Toxicology Program 

J. Everitt, D.V.M. 

Chemical Industry Institute of Toxicology 

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

Experimental Pathology Laboratories, Inc. 

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

Tox Path Inc. 

J. Pletcher, D.V.M. 

Pathology Associates International 

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

Experimental Pathology Laboratories, Inc. 

J. Ward, D.V.M., Ph.D. 

National Cancer Institute 

Biotechnical Services, Inc. 

Prepared Technical Report 

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

J.R. Carlton, B.A. 

G. Gordon, M.A. 

L.M. Harper, B.S. 

A.M. Macri-Hanson, M.A., M.F.A. 

E.S. Rathman, M.S. 

W.D. Sharp, B.A., B.S. 

 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 

3 

CONTENTS
 

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

EXPLANATION OF LEVELS OF EVIDENCE OF CARCINOGENIC ACTIVITY ............. 8
 

TECHNICAL REPORTS REVIEW SUBCOMMITTEE ................................ 9
 

SUMMARY OF TECHNICAL REPORTS REVIEW SUBCOMMITTEE COMMENTS .......... 10
 

INTRODUCTION ......................................................... 13
 

MATERIALS AND METHODS ................................................ 19
 

RESULTS ............................................................... 27
 

DISCUSSION AND CONCLUSIONS ............................................ 47
 

REFERENCES ........................................................... 53
 

APPENDIX A Summary of Lesions in Male Rats in the 2-Year Whole-Body Exposure Study
 

of 60-Hz Magnetic Fields ......................................... 63
 

APPENDIX B Summary of Lesions in Female Rats in the 2-Year Whole-Body Exposure Study
 

of 60-Hz Magnetic Fields ......................................... 83
 

APPENDIX C Summary of Lesions in Male Mice in the 2-Year Whole-Body Exposure Study
 

of 60-Hz Magnetic Fields ......................................... 101
 

APPENDIX D Summary of Lesions in Female Mice in the 2-Year Whole-Body Exposure Study
 

of 60-Hz Magnetic Fields ......................................... 119
 

APPENDIX E Magnetic Field Production and Monitoring ............................. 137
 

APPENDIX F Measurement of 60-Hz Magnetic and Electric Fields
 

at the Illinois Institute of Technology Research Institute .................... 147
 

APPENDIX G Ingredients, Nutrient Composition, and Contaminant Levels 

in NTP-2000 Rat and Mouse Ration ................................. 161
 

APPENDIX H Sentinel Animal Program ......................................... 165
 
4 60-Hz Magnetic Fields, NTP TR 488 

 

5 

ABSTRACT
 

Electric and magnetic fields are associated with the 

production, transmission, and use of electricity; thus, 

the potential for human exposure is high. These 

electric and magnetic fields are predominantly of low 

frequency (60 Hz in the United States and 50 Hz in 

Europe) and generally of low intensity. Epidemiology 

studies have suggested a potential for increased breast 

cancer, brain cancer, and leukemia rates with increasing magnetic field exposure. However, these results 

are controversial and a National Research Council 

found no compelling evidence for an EMF effect on 

cancer. Because of the controversy and given the 

widespread exposure to low-intensity, 60-Hz magnetic 

fields in industrialized societies, standard toxicology 

studies and long-term carcinogenesis studies were 

conducted using traditional rodent models. Male and 

female F344/N rats and B6C3F1 mice were exposed

to 60-Hz magnetic fields by whole-body exposure for 

2 years. 

2-YEAR STUDY IN RATS 

Groups of 100 male and 100 female rats were exposed 

to 60-Hz magnetic fields at intensities of 0.02, 2, or 

10 G for 18.5 hours per day, 7 days per week, for 

106 weeks. Groups of 100 male and 100 female control rats were housed in the same exposure chambers 

without applied magnetic fields. Additional groups 

of 100 male and 100 female rats were intermittently 

exposed (1 hour on and 1 hour off) to a 10 G 60-Hz 

field 18.5 hours per day, 7 days per week, for 

106 weeks. The highest field intensity (10 G) is 

approximately 5,000-fold greater than what was 

considered high intensity for homes in epidemiology 

studies in humans. 

Survival and Body Weights 

Survival and mean body weights of exposed groups of 

male and female rats were similar to those of the 

control groups. 

Pathology Findings 

The incidences of thyroid gland C-cell adenoma and 

carcinoma in 0.02 G male rats, adenoma in 2 G 

males, and adenoma or carcinoma (combined) in 0.02 

and 2 G males were significantly greater than in the 

control group. The incidence of mononuclear cell 

leukemia in males in the 10 G intermittent group was 

significantly less than in the control group. 

2-YEAR STUDY IN MICE 

Groups of 100 male and 100 female mice were 

exposed to 60-Hz magnetic fields at intensities of 

0.02, 2, or 10 G for 18.5 hours per day, 7 days per 

week, for 106 weeks. Groups of 100 male and 

100 female control mice were housed in the same 

exposure chambers without applied magnetic fields. 

Additional groups of 100 male and 100 female mice 

were intermittently exposed (1 hour on and 1 hour 

off) to a 10 G 60-Hz field 18.5 hours per day, 7 days 

per week, for 106 weeks. 

Survival and Body Weights 

Survival of male mice exposed to 10 G was significantly less than that of control mice after 2 years; 

survival of all other exposed groups of mice was similar to that of control mice. Mean body weights of 

exposed groups of male and female mice were similar 

to those of the control groups throughout the study. 

Pathology Findings 

The incidences of alveolar/bronchiolar adenoma were 

significantly decreased in 0.02 and 2 G male mice and 

2 G female mice relative to the control groups; the 

incidences of alveolar/bronchiolar adenoma or carcinoma (combined) were significantly less in males and 

females exposed to 2 G than in the control groups. In 

female mice, the incidence of malignant lymphoma in 

the 10 G intermittent group was significantly less than 

in the controls. 
__________ 


 

6 60-Hz Magnetic Fields, NTP TR 488 

CONCLUSIONS
 

Under the conditions of these 2-year whole-body 

exposure studies, there was equivocal evidence of carcinogenic activity* of 60-Hz magnetic fields in male 

F344/N rats based on increased incidences of thyroid 

gland C-cell neoplasms in the 0.02 and 2 G groups. 

There was no evidence of carcinogenic activity in 

female F344/N rats or male or female B6C3F1 mice 

exposed to 0.02, 2, or 10 G, or 10 G intermittent 

60-Hz magnetic fields. 

In exposed rats and mice, there were no increased 

incidences of neoplasms at sites for which epidemiology studies have suggested an association with 

magnetic fields (brain, mammary gland, leukemia). 

* Explanation of Levels of Evidence of Carcinogenic Activity is on page 8. A summary of the Technical Reports Review Subcommittee 

comments and the public discussion on this Technical Report appears on page 10. 
60-Hz Magnetic Fields, NTP TR 488 7 

Summary of the 2-Year Carcinogenesis Studies of 60-Hz Magnetic Fields 

Male Female Male Female 

F344/N Rats F344/N Rats B6C3F Mice B6C3F Mice 1 1 

Exposure field Control, 0.02, 2, or 

10 G continuous, or intensity 10 G intermittent 

Body weights Exposed groups similar 

to control group 

Survival rates 57/100, 46/100, 47/100, 

48/100, 59/100 

Nonneoplastic None 

effects 

Neoplastic effects None 

Uncertain findings Thyroid Gland (C-cell): 

adenoma (15/99, 25/100, 

26/100, 23/100, 

18/100); carcinoma 

(1/99, 7/100, 4/100, 

2/100, 5/100); adenoma 

or carcinoma (16/99, 

31/100, 30/100, 25/100, 

22/100) 

Level of evidence Equivocal evidence 

of carcinogenic 

activity 

Control, 0.02, 2, or 

10 G continuous, or 

10 G intermittent 

Exposed groups similar 

to control group 

59/100, 68/100, 60/100, 

61/100, 58/100 

None 

None 

None 

No evidence 

Control, 0.02, 2, or Control, 0.02, 2, or 

10 G continuous, or 10 G continuous, or 

10 G intermittent 10 G intermittent 

Exposed groups similar Exposed groups similar 

to control group to control group 

76/100, 72/100, 84/100, 70/100, 74/100, 79/100, 

62/100, 74/100 74/100, 77/100 

None None 

None None 

None None 

No evidence No evidence 
	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

8 60-Hz Magnetic Fields, NTP TR 488 

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. 

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. 
__________ 


 


 


 


 


 


 


 


 

60-Hz Magnetic Fields, NTP TR 488 9 

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 60-Hz magnetic fields on 

11 March 1998 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.
 

Gary P. Carlson, Ph.D., Chairperson Susan M. Fischer, Ph.D. 

School of Health Sciences M.D. Anderson Cancer Center 

Purdue University University of Texas 

West Lafayette, IN Smithville, TX 

A. John Bailer, Ph.D., Principal Reviewer Thomas L. Goldsworthy, Ph.D. 

Department of Mathematics and Statistics Integrated Laboratory Systems 

Miami University Research Triangle Park, NC 

Oxford, OH 

Stephen S. Hecht, Ph.D.* 

Steven A. Belinsky, Ph.D. University of Minnesota Cancer Centers 

Inhalation Toxicology Research Institute Minneapolis, MN 

Kirkland Air Force Base 

Albuquerque, NM Michele Medinsky, Ph.D.
 Chemical Industry Institute of Toxicology

James S. Bus, Ph.D., Principal Reviewer Research Triangle Park, NC 

Health and Environmental Sciences 

Dow Chemical Company Jose Russo, M.D. Midland, MI Fox Chase Cancer Center 

Philadelphia, PA

Linda A. Chatman, D.V.M. 

Pfizer, Inc. 

Groton, CT 

John M. Cullen, Ph.D., V.M.D., Principal Reviewer 

Department of Microbiology, Parasitology, and Pathology 

College of Veterinary Medicine 

North Carolina State University 

Raleigh, NC 

Special Reviewers 

Clinton J. Grubbs, Ph.D. Maria Stuchly, Ph.D.

Department of Electrical and Computer Engineering Nutritional Sciences Department University of Victoria University of Alabama Victoria, BC, Canada Birmingham, AL 

Martin Misakian, Ph.D. 

National Institute of Standards and Technology 

Gaithersburg, MD 

* Did not attend 

 

10 60-Hz Magnetic Fields, NTP TR 488 

SUMMARY OF TECHNICAL REPORTS REVIEW SUBCOMMITTEE COMMENTS
 

On 11 March 1998, the draft Technical Report on 

the toxicology and carcinogenesis studies of 60-Hz 

magnetic fields received public review by the National 

Toxicology Program’s Board of Scientific Counselors’ 

Technical Review Subcommittee. The review meeting was held at the National Institute of Environmental 

Health Sciences, Research Triangle Park, NC. 

Dr. G.A. Boorman, NIEHS, introduced the toxicology and carcinogenesis studies of 60-Hz magnetic 

fields by discussing the uses of magnetic fields and 

the rationale for study, describing the experimental 

design, reporting on survival and body weight effects, 

and commenting on compound-related neoplastic and 

nonneoplastic lesions in rats and mice. The proposed 

conclusions for the 2-year studies were equivocal evidence of carcinogenic activity in male rats and no 

evidence of carcinogenic activity in female rats and 

male and female mice. 

Dr. Cullen, a principal reviewer, agreed with the proposed conclusions. He thought the use of two or multiple sections of the thyroid gland along with the use 

of a new diet might impact on comparisons with the 

historical control database. Dr. Boorman said that 

because second cuts had to be made for some rats, 

second cuts were done on the thyroid glands of all rats 

to eliminate bias. He agreed that double sectioning 

along with the new diet lessened the usefulness of 

the historical controls for comparisons. Dr. Cullen 

asked what parameters were evaluated in the pineal 

gland since this organ is not routinely examined. 

Dr. Boorman said that the pineal gland examination 

centered on diagnoses of the presence of small 

lysosomal granules. Dr. Cullen suggested that the 

effect of the age differences between weaned animals 

of 6 to 8 weeks of age and human neonates in their 

sensitivity to EMF effects be discussed. Dr. Boorman 

noted the study by Dr. R. Mandeville, who looked at 

the effects of exposures from the 20th day of gestation 

through parturition and weaning in female rats. 

Dr. Bus, the second principal reviewer, agreed in 

principle with the proposed conclusions. He suggested that since the unexpected thyroid gland neoplasm 

findings seem unlikely to be attributable to magnetic 

field exposure, the NTP should consider emphasizing 

this point in the conclusion. Dr. Boorman agreed to 

address this issue in the discussion. Dr. Bus commented that the discussion implied that the findings of 

the current study are not consistent with reported 

associations of magnetic field exposures and human 

childhood and adult leukemias. Because the study 

design did not include pre- or early postnatal exposures, he suggested the findings of this study may not 

be particularly relevant to reports of human childhood 

leukemias. 

Dr. Bailer, the third principal reviewer, agreed in 

principle with the proposed conclusions. He noted 

other dose-related increased neoplasm incidences in 

male rats, in particular skin trichoepithelioma and 

basal cell adenoma, as well as skin squamous cell 

papilloma and keratoacanthoma, and asked whether 

these results might support some evidence of carcinogenic activity. Dr. J.R. Hailey, NIEHS, explained 

that the relevant analysis is a combined analysis of 

these skin neoplasms as they are all thought to be 

derived from basal epithelium. Dr. J.K. Haseman, 

NIEHS, said that if one looks at the combination of 

these basal epithelial neoplasms, there are more 

neoplasms overall in the control group than in the 

exposed groups. 

Three ad hoc expert consultants (Drs. Grubbs, 

Misakian, and Stuchly) were present to assist with the 

reviews. Dr. Stuchly said the report comprehensively 

described the study design, results, and data analysis 

and the essential findings were properly addressed. 

She said that from her engineering viewpoint, the only 

limitation was poor quantification of the exposure 

conditions. Particularly, the maps of field uniformity 

within the space occupied by the animals were not 

provided, and the contract facility did have the 

capability to compute uniformity of exposure fields. 

Dr. Boorman agreed to add an appendix that detailed 

the exposure conditions. Dr. Stuchly noted that calculations of induced surface currents from alternating 

fields were considerably different for humans and 

rodents. Dr. Misakian responded to Dr. Stuchly’s 

concerns about the field conditions, stating that during 

site visits by the National Institute of Standards and 

Technology, uniformity of exposure was characterized 

by measuring on each shelf where animals were 

located and also on a perimeter line that enclosed the 

area. Approximately 18 measurements were made on 
60-Hz Magnetic Fields, NTP TR 488 11 

the perimeter and compared with the field value 

at the center of each shelf. All measured field values were within 10% of the targeted field levels 

reported. Dr. Misakian discussed the differences 

between circularly polarized and linearly polarized 

magnetic fields, and both he and Dr. Stuchly agreed 

that people are primarily exposed to linearly polarized 

magnetic fields. 

Dr. Cullen moved that the Technical Report on 

whole-body exposures to 60-Hz magnetic fields be 

accepted with the revisions discussed and the conclusions as written for male rats, equivocal evidence 

of carcinogenic activity, and for female rats and 

male and female mice, no evidence of carcinogenic 

activity. Dr. Bus seconded the motion. There was 

some discussion as to whether “slightly increased 

incidences of thyroid gland C-cell neoplasms” should 

be modified by deleting “slightly.” Dr. J.R. Bucher, 

NIEHS, suggested “occurrence of” instead of “slightly 

increased incidences” as less directly associating the 

neoplasms with exposure. In response to a query by 

Dr. Cullen, Dr. Haseman said the P value for the 0.02 

and 2 G groups under “adenoma or carcinoma” was 

less than 0.01. Dr. Bus said there needs to 

be wording that qualifies why the call is equivocal. 

Dr. Medinsky noted that the definition of “equivocal” 

in the report uses the word “marginal,” so marginal 

defines equivocal. Dr. Bailer moved to amend the 

motion by deleting “slightly.” Dr. Medinsky seconded the amendment, which was accepted by seven 

yes votes to one no vote (Dr. Bus) with one abstention 

(Dr. Goldsworthy). Dr. Bus stated that there still 

needed to be wording suggesting a non-exposure 

related increase in thyroid gland C-cell neoplasms. 

Dr. Haseman suggested identifying the specific groups 

in which the increase was seen. Dr. Bailer moved to 

further modify his original amendment to read “based 

on increased incidences of thyroid gland C-cell neoplasms in the 0.02 and 2 G groups.” Dr. Russo seconded the amended motion, which was accepted by 

eight yes votes with one abstention 

(Dr. Goldsworthy). 
12 60-Hz Magnetic Fields, NTP TR 488 

 

13 

INTRODUCTION
 

Electric and magnetic fields associated with the production, transmission, and use of electricity are ubiquitous in industrialized society. The electric and 

magnetic fields associated with alternating current are 

predominantly of low frequency (50 or 60 Hz) and 

generally of low intensity. Electric fields exist when 

there is electric potential (voltage) in a line, while 

magnetic fields exist only when there is current flow 

(Miller and Schroeer, 1987). Electric and magnetic 

fields are often referred to as electromagnetic fields, 

or EMFs. Electric fields are easily shielded by trees, 

walls, and other material, whereas magnetic fields 

usually penetrate nonferrous material. Thus, most 

exposure in the home is to magnetic fields, and recent 

research has focused on potential adverse biological 

effects of exposure to magnetic fields. Most residential exposure is to magnetic fields that are less 

than 2 milligauss (mG) although many commonly 

used household appliances generate fields that exceed 

this intensity (Gauger, 1985). In some industries, 

mean workplace magnetic field exposure may exceed 

10 mG (Theriault et al., 1994). 

Electromagnetic radiation, such as X-rays, ultraviolet 

light, or other ionizing radiation, have sufficient 

energy to damage DNA. However, low-frequency 

(e.g., 60 Hz) fields are of very low energy and are not 

sufficient to alter DNA structure or directly cause 

genetic injury (Juutilainen and Liimatainen, 1986; 

Rosenthal and Obe, 1989). Further, the magnetic 

fields produced by 60-Hz alternating current are of 

much lower intensity than the earth’s static magnetic 

fields, which are 300 to 500 mG, depending on the 

geographic location, presence of ferrous materials, 

and other factors. Thus, many had assumed that 

exposure to low-frequency, low-intensity magnetic 

fields could not pose a health hazard. This view was 

challenged by Wertheimer and Leeper (1979), who 

were supported by a second study by Savitz et al. 

(1988), reporting that children living in homes with 

potentially high magnetic fields had a greater 

incidence of childhood leukemia than children living 

in homes that would be expected to have lower 60-Hz 

magnetic field exposures. Other studies (Fulton 

et al., 1980; Coleman et al., 1989) failed to find an 

association between wire codes and the occurrence of 

childhood cancer. 

TOXICITY 

Experimental Animals 

Experimental animal studies to evaluate the potential 

effects of magnetic fields are difficult to conduct, and 

the exposure variables are difficult to control. Most 

reports of animal studies on the effects of magnetic 

fields do not give sufficient details on the exposure 

parameters or the local static magnetic fields of the 

earth to permit assessment of results. Conflicting 

results have been reported from animal studies on the 

potential hazard of exposure to electric and magnetic 

fields (Kavet and Banks, 1986; Kavet, 1996). Laboratory studies have shown that animals can respond 

behaviorally to electric fields; the evidence for behavioral response to magnetic fields is more tenuous, but 

in either case, no general adverse behavioral effects 

have been observed. While neuroendocrinologic 

effects have been reported in animals, these effects 

have not been associated with adverse health effects 

(NRC, 1997). In the NTP studies, no evidence of 

toxicity was observed in male or female F344/N rats 

or B6C3F mice continuously exposed to 0.02, 2, or 1 

10 G for 18.5 hours per day, 7 days per week 

for 8 weeks or intermittently exposed (1 hour on, 

1 hour off) to 10 G for the same period (NTP, 1996; 

Boorman et al., 1997). 

Humans 

The literature on the potential toxicity of 60-Hz 

magnetic fields includes human (epidemiology) studies 

and clinical studies. Most of this literature is difficult 

to evaluate due to the complex nature of the fields and 

the lack of adequate descriptions of the exposures 

or the potential confounding factors. Epidemiology 

studies can provide only an estimate of the exposures, 

because exposure in the home varies according to the 

location in the house; the number and type of appliances in use; the current load on the outside lines, 

which varies with electrical demand; and development 

and changes within a community, which cause 
14 60-Hz Magnetic Fields, NTP TR 488 

variations in the magnetic fields over time. Ambient 

levels of 60-Hz magnetic fields in residences and most 

workplaces are typically in the range from 0.1 to 

3 mG (NRC, 1997). Further, residential exposures 

account for only a portion of a person’s total magnetic 

field exposure because exposures also occur in the 

school or workplace, during travel, and during 

outdoor activities (Feychting et al., 1996; Friedman 

et al., 1996; Kheifets et al., 1997). 

Studies of residential exposures suggest possible 

increased rates of childhood leukemia (Savitz et al., 

1988; Feychting and Ahlbom, 1993, 1995) and brain 

cancer (Wertheimer and Leeper, 1979; Savitz et al., 

1988) in homes expected to have higher magnetic 

field intensities. Studies of occupational exposure 

of electricians suggest possible increased risks of 

leukemia (Theriault et al., 1994), brain cancer (Savitz 

and Loomis, 1995), and breast cancer (Matanoski 

et al., 1991). However, the studies are not always 

consistent. Savitz and Loomis (1995) reported increased incidences of brain cancer but not leukemia in 

electricians, while Theriault et al. (1994) reported 

increased incidences of leukemia but not brain cancer. 

Other potential indicators of toxicity in humans 

include headaches, depression, impaired neuropsychologic performance, and suicide, but the results are 

inconsistent and the studies are of mixed quality 

(NRC, 1997). In a series of studies, no effects of 

200 mG exposure on nocturnal melatonin concentrations were seen in volunteers (Graham et al., 1996, 

1997). 

REPRODUCTIVE TOXICITY 

A review of the literature concluded that laboratory 

and epidemiological studies have not yielded conclusive data to suggest that magnetic field exposures 

induce adverse reproductive effects under the conditions studied (Chernoff et al., 1992). Maffeo et al. 

(1988) and Jauchem (1993) have also suggested that 

the evidence for any reproductive effects is very 

weak. 

Experimental Animals 

There have been over 70 experimental animal and 

in vitro studies that evaluated the effects of lowfrequency (30- to 300-kHz) or very low-frequency 

(30-kHz or less) EMF exposure on some aspect of 

reproduction or teratology (Delgado et al., 1982; 

Juutilainen and Saali, 1986; Beers, 1989; Eckert, 

1992). Many embryology studies used the chicken 

embryo to evaluate teratogenesis after 48 to 52 hours 

of development (Martin, 1992; Brent et al., 1993; 

Koch et al., 1993). In chicken eggs exposed to magnetic fields, some embryos showed retarded development (Juutilainen and Saali, 1986; Martin, 1988), 

while in other studies, there were no differences in 

embryos from exposed or control eggs (Maffeo et al., 

1984). Medaka fish eggs exposed to a 1 G 60-Hz 

magnetic field showed no gross abnormalities, but 

embryonic growth was retarded (Cameron et al., 

1985). Magnetic field exposures inhibited proliferation of sea urchins (Cameron et al., 1993). No 

reproductive or developmental effects were seen in 

Sprague-Dawley rats exposed to magnetic fields of up 

to 10 G, 18.5 hours per day for as long as 6 months 

(NTP, 1996; Ryan et al., 1996). 

Humans 

Studies of the reproductive effects of EMF exposures 

in humans include studies of exposures to video 

display terminals, power lines, and household appliances. The video display terminal studies were 

generally negative for reproductive effects, while 

the reproductive risks of power lines and home 

appliances were less consistent (Brent et al., 1993). 

The National Research Council (NRC, 1997) concluded that there was no substantial or conclusive 

evidence for adverse reproductive effects caused by 

residential exposure to electric and magnetic fields. 

NEUROENDOCRINOLOGIC TOXICITY 

IN EXPERIMENTAL ANIMALS 

Several studies have suggested that exposure to 

electric or magnetic fields may suppress nocturnal 

melatonin concentrations in rodents (Wilson et al., 

1986, 1989; Lerchl et al., 1991; Reiter, 1992; 

Stevens et al., 1992; Anderson, 1993; Stevens, 1993). 

In one study, serum melatonin concentrations but not 

pineal gland melatonin synthesis were reduced in 

Sprague-Dawley rats, suggesting that degradation 

or tissue uptake of melatonin may be stimulated 

by exposure to electric fields (Grota et al., 1994). 

Another study reported that serotonin-N-acetyltransferase, the rate-limiting enzyme for melatonin 

production, may be inhibited by magnetic field 

exposure (Olcese and Reuss, 1986). No alterations 

occurred in serum or pineal gland melatonin or pineal 

gland serotonin-N-acetyltransferase in male or female 
60-Hz Magnetic Fields, NTP TR 488 15 

F344/N rats or B6C3F1 mice exposed to magnetic 

fields of up to 10 G for 8 weeks (NTP, 1996). In that 

study, the magnitude of the pineal gland response was 

evaluated at only one nocturnal time point; consequently, the duration of the melatonin secretion could 

not be determined. When this study was repeated in 

mice, with evaluation of pineal gland response at 

multiple nocturnal time points, no effect of magnetic 

field exposures was observed. The NTP studies 

employed linear magnetic fields, and it has been 

suggested that circularly polarized magnetic fields 

will cause decreased melatonin concentrations in rats 

even though linear fields will not (Kato et al., 

1994a,b). Melatonin has been reported to be oncostatic (Kerenyi et al., 1990; Reiter, 1992, 1993). 

Exposure to extremely low-frequency magnetic fields 

has been shown to block melatonin’s growth inhibition 

of MCF-7 breast cancer cells (Liburdy et al., 1993), 

and melatonin suppression may be associated with 

breast cancer, one of the cancers hypothesized to be 

increased by magnetic field exposure (Stevens et al., 

1992). More recent studies have not shown consistent 

alterations in nocturnal melatonin concentrations in 

hamsters exposed to 60-Hz magnetic fields (Truong 

et al., 1996), nor was there an effect on reproductive 

maturation (Yellon, 1996). 

CARCINOGENICITY 

Experimental Animals 

Several short-term (180-day) rodent carcinogenesis 

studies of magnetic fields have been conducted 

(Anderson, 1993). Static magnetic fields did not enhance the development of spontaneous lymphoblastic 

leukemia in female AKR mice (Bellossi, 1986). In 

skin tumor promotion models, there has been either a 

marginal increase in the incidence of skin papillomas 

with magnetic field exposure (McLean et al., 1991) or 

no increase in neoplasm rate (Rannug et al., 1993a). 

In SENCAR mice, intermittent magnetic field exposure was associated with a marginal increase in the 

number of skin tumors per tumor-bearing animal 

(Rannug et al., 1994). In three independent studies in 

SENCAR mice, the results were variable and did not 

support an effect of magnetic fields on skin tumor 

promotion in this model (McLean et al., 1997). In 

Sprague-Dawley rats, there was no increase in the 

incidence of liver foci following magnetic field exposure (Rannug et al., 1993b); following partial 

hepatectomy and treatment with the tumor initiator 

diethylnitrosamine, magnetic field exposure was 

associated with a slight reduction in size and number 

of liver foci compared to unexposed controls (Rannug 

et al., 1993c). 

Humans 

The potential of magnetic field exposure to promote 

breast cancer has been suggested by several epidemiology studies, but the data are far from conclusive. 

Wertheimer and Leeper (1979) and Savitz et al. 

(1988) classified the residences of children by using 

wire codes as surrogates for predicted magnetic fields 

within the home (Barnes et al., 1989). Some epidemiology studies of residential exposure showed little 

or no correlation between estimated home exposure to 

magnetic fields and incidence of childhood leukemia 

(Fulton et al., 1980; Ahlbom, 1988; Coleman et al., 

1989; Myers et al., 1990). Some epidemiology 

studies of workplace exposure to EMFs suggested a 

potential occupational risk for increased leukemia 

rates (Gilman et al., 1985), while other studies were 

negative (Fulton et al., 1980; Myers et al., 1990). 

These studies have been questioned concerning matching controls and tumor groupings (ORAU, 1992). 

The electric and magnetic field exposures were highly 

variable in these occupational studies (Deadman et al., 

1988), and many other confounding factors have been 

identified (Greenberg and Shuster, 1985; Michaelson, 

1987; Beers, 1989). Thus, neither epidemiology studies nor experimental animal studies have provided 

conclusive evidence that magnetic fields increase the 

incidence of cancer or alter the carcinogenic process. 

GENETIC TOXICITY 

The potential genotoxic effects of low-frequency 

EMFs have been investigated in a variety of studies 

covering a broad range of test types and endpoints; 

thorough reviews of these studies were presented 

by McCann et al. (1993) and Murphy et al. (1993). 

With few exceptions, the data from laboratory experiments support the conclusion that low-frequency 

EMFs, as well as electric and magnetic fields separately, present little if any risk of induced genetic 

damage under the conditions of investigation. It is 

generally accepted that the energy from low-frequency 

electromagnetic radiation is insufficient to produce 

direct DNA damage (Kavet, 1996). However, electric 

field exposures characterized by sparking, highintensity pulsing, or corona effects may represent a 

greater genotoxic risk, although the information from 

studies that involved such exposures is not definitive 
16 60-Hz Magnetic Fields, NTP TR 488 

(McCann et al., 1993; Murphy et al., 1993). Reports 

of significantly increased chromosomal aberration frequencies in peripheral blood lymphocytes of switchyard workers exposed to 50-Hz sinusoidal EMFs, 

electric shocks, and other hazards of this workplace 

environment (Nordenson et al., 1984, 1988) and of 

dose-related increases in micronuclei in bone marrow 

cells of mice exposed to 50-Hz sinusoidal electrical 

fields of varying intensities (170 to 290 kV/m) 

(El Nahas and Oraby, 1989) raised a concern about 

the genetic effects of these exposures. However, 

neither of these studies has been independently confirmed, and numerous in vitro investigations of chromosomal or mutational effects conducted under carefully controlled and defined laboratory conditions with 

human cells (Nordenson et al., 1984; Cohen et al., 

1986a,b; Rosenthal and Obe, 1989; Livingston et al., 

1991; Scarfi et al., 1991) and rodent cells (Wolff 

et al., 1980; Livingston et al., 1991; Fiorio et al., 

1993; Suri et al., 1996) have not confirmed the 

potential for EMF-induced genetic damage. Also, 

results from DNA repair (Pino et al. 1985; Whitson 

et al., 1986; Reese et al., 1988; Frazier et al., 1990) 

and DNA damage (Fairbairn and O’Neill, 1994; 

Antonopoulos et al., 1995) studies with mammalian 

cells exposed to EMFs were negative, as were results 

from bacterial mutagenicity assays (Moore, 1979; 

Thomas and Morris, 1981; Juutilainen and 

Liimatainen, 1986; Shimizu et al., 1989; Morandi 

et al., 1996). 

Effects of electric and magnetic fields on biological 

systems that might potentially be related to cancer 

induction may include enhancement of cell proliferation, and earlier studies have been reviewed (McCann 

et al., 1993; Murphy et al., 1993). Investigations of 

the effects of EMF exposure on cell cycle progression 

have yielded mixed results, and possible modes of 

action whereby EMFs might enhance cell proliferation 

have not been determined (Murphy et al., 1993; 

Kavet, 1996). Livingston et al. (1991) and Miyakoshi 

et al. (1996) found no exposure-related changes in 

clonogenicity and/or cell cycle time of Chinese 

hamster ovary cells cultured for at least 96 hours in 

the presence of 60-Hz electromagnetic or magnetic 

fields, and Cridland et al. (1996) detected no effects 

on the rate of DNA synthesis, a measure of cell 

proliferation, in normal human fibroblasts exposed to 

50-Hz magnetic fields for up to 30 hours. Other 

investigators have reported stimulation of human 

peripheral blood lymphocyte proliferation in vitro 

after exposure to 50-Hz, 50 G EMFs (Rosenthal and 

Obe, 1989; Antonopoulos et al., 1995) or 50-Hz 

pulsed magnetic fields (Scarfi et al., 1994). 

The possible effects of EMF exposure on epigenetic 

endpoints, such as transcriptional activation or modulation of gene expression, have been investigated at a 

number of laboratories with conflicting results (Blank 

et al., 1992; Goodman et al., 1992, 1994a,b; Phillips, 

1993; Gold et al., 1994; Libertin et al., 1994; Saffer 

and Thurston, 1995). For example, exposure to 

extremely low-frequency EMFs was reported to stimulate transcription of c-fos, c-jun, c-myc and/or 

protein kinase C genes in various cell types, including 

human HL60, mouse myeloma, and yeast cells (Wei 

et al., 1990; Goodman et al., 1992, 1994a,b; Phillips, 

1993; Lin et al., 1994). However, Lacy-Hulbert 

et al. (1995) were unable to duplicate the c-myc transcriptional stimulation in HL60 human leukemic cells, 

despite the use of carefully controlled experimental 

protocols and a variety of sophisticated analytical 

methods capable of detecting very small alterations 

in transcriptional activation. In addition, Saffer and 

Thurston (1995) used ribonuclease protection assays 

as another sensitive means of measuring transcriptional activation in HL60 cells exposed to extremely 

low-frequency EMFs and found no alterations in gene 

expression. Furthermore, Miyakoshi et al. (1996) 

reported that similar exposure of cultured Chinese 

hamster ovary cells to 60-Hz EMFs did not alter cell 

growth rate or expression of c-myc. Several reviews 

of the controversial reports of transcriptional modulation following EMF exposures are found in the literature (Adair, 1992; Florig, 1992; Phillips, 1993; 

Lacy-Hulbert et al., 1995; Blank and Goodman, 

1997), and the current consensus among investigators in the field is that observations of transcriptional 

stimulation resulted from unique experimental 

conditions that could not be duplicated in any 

of several independent laboratories under carefully 

monitored conditions. 

In summary, although a number of well-designed and 

conducted genotoxicity experiments with EMFs have 

been published, not all types of exposures nor all 

of the commonly employed assays have been used, 

and many studies are deficient in design, conduct, 

or reporting format (McCann et al., 1993; Murphy 

et al., 1993). Accordingly, the accumulated evidence 

implies little risk of direct genetic damage from EMF 

exposure. 
60-Hz Magnetic Fields, NTP TR 488 17 

STUDY RATIONALE AND DESIGN 

In 1988, in response to an epidemiology report by 

Savitz et al. (1988) that appeared to confirm an earlier 

study by Wertheimer and Leeper (1979), the Department of Energy and the Electric Power Research Institute (EPRI) nominated 60-Hz (power line frequency) 

electric and magnetic fields to the NIEHS to be 

considered for evaluation by the NTP. In 1990, the 

National Association of Regulatory Utility Commissioners (representing all 50 states; Washington, DC; 

Puerto Rico; and the Virgin Islands) and the Large 

Public Power Council (representing 17 of the largest 

publicly owned utilities in the United States) requested 

that the NIEHS undertake studies to evaluate the 

unresolved potential hazard of exposure to electric and 

magnetic fields. Therefore, given the widespread 

exposure to low intensity, 60-Hz magnetic fields in 

industrialized societies, standard toxicology studies 

and long-term carcinogenesis studies were conducted 

using the traditional rodent models. 

Because several effects have been reported in the 

literature, a draft protocol was circulated to approximately 80 experts to solicit comments on appropriate 

studies for magnetic field evaluation. The toxicity, 

developmental, and reproductive studies preceded the 

carcinogenicity studies. The standard toxicity studies 

in F344/N rats and B6C3F1 mice included evaluation

of pineal gland function in addition to the standard 

histopathology, hematology, and clinical chemistry 

evaluations. Standard comprehensive protocols for 

the assessment of developmental toxicology in female 

Sprague-Dawley rats and for a continuous breeding 

study in Sprague-Dawley rats (the usual strain and 

species for NTP assessment of developmental and 

reproductive effects) were included. The few existing 

animal studies were generally short-term promotion 

studies and not long-term studies that would address 

the potential carcinogenic hazard of magnetic fields, 

such as the studies that have traditionally been 

conducted by the NTP. There was no indication of 

magnetic field toxicity in any of these studies (NTP, 

1996; Ryan et al., 1996; Boorman et al., 1997). 

Because electric and magnetic field exposures are 

very complex and a vast combination of field parameters could be evaluated, the circulated draft protocol 

solicited comments on appropriate field parameters for 

evaluation. A workshop was held at NIEHS to assist 

in determining the field parameters for study. While 

there are different frequencies of exposure in homes 

with different appliances, and 50 Hz is the predominant field frequency in western Europe and Japan, the 

predominant frequency in United States homes is 

60 Hz; therefore, it was decided that all exposures 

would use a 60-Hz frequency. 

The field intensities were limited by design considerations. The creation of magnetic fields for animal 

exposure requires large coils. As field intensities increase, noise, heat, vibration, and stray fields become 

a problem for technicians and control animals. A 

manageable maximum field intensity of 10 G was 

selected for the present studies; this is approximately 

5,000-fold greater than what was considered high 

intensity for homes in the epidemiology studies. 

Because it was possible that on-and-off changes in the 

magnetic field, and not necessarily the field intensity 

itself, were important, a second high-intensity group 

was included, with 1-hour-on and 1-hour-off exposures. Because current density within a body is related to the body volume and shape, the exposure levels 

for rodents needs to be increased to obtain similar 

current densities (Xi et al., 1994); thus, the lowest 

field intensity used in the present studies (0.02 G) 

gives rodents an exposure that may be slightly higher 

than residential exposures for humans. A third field 

intensity, 2 G, intermediate between the other two 

field intensities, was also used. 

While power line magnetic field exposures are predominantly sine-wave fields, residential and occupational exposures may include square waves, sawtooth 

waves, and other wave forms. Harmonics (120 Hz, 

180 Hz, etc.) may also be found. Further, as appliances are switched on and off, spikes or transients in 

fields may occur. It is not feasible to evaluate all 

possible variables in large animal studies. Therefore, 

this study used linearly polarized, pure sine-wave 

exposures at 60 Hz, with the fields turned on when 

the sine wave was at zero amplitude and gradually 

increased over seven to nine cycles (between 0.11 and 

0.15 seconds) to full intensity, and similarly gradually 

decreased to avoid transients. The NIEHS studies 

evaluate the predominant component (60-Hz sinewave magnetic fields) without all the complexities of 

the exposures that occur in residential and occupational settings. 

To increase the statistical power for detecting potential 

carcinogenic effects, sample sizes in the 2-year studies 
18 60-Hz Magnetic Fields, NTP TR 488 

were increased from the usual 50 animals per group to 

100 per group. The gain in power achieved by these 

additional animals depends upon the background 

neoplasm rate and the magnitude of the response. For 

example, for a site with a background incidence of 

20%, the likelihood that a doubling of neoplasm 

incidence would be significant at a P value less than 

0.05 is approximately 64% for groups of 50 animals, 

whereas with groups of 100 the likelihood of detection 

increases to 91%. 

According to a National Research Council report 

(NRC, 1997), there is no conclusive and consistent 

evidence that exposure to residential electric and 

magnetic fields produces cancer, adverse neurobehavioral effects, or reproductive and developmental 

effects. The report failed to make conclusions relative 

to evidence of occupational exposure, but noted an 

association between residential wiring configurations 

and childhood leukemia. However, the contradictory 

report of Linet et al. (1997) found no association 

between childhood leukemia and wiring codes, 

although a small increased risk for childhood leukemia 

was associated with residential exposures of about 

3 mG. Many scientists still consider the question of 

an association of increased risk for cancer with residential or occupational exposure to magnetic fields 

unresolved. 

Funds authorized by the Energy Policy Act of 1992 

supported additional animal studies to evaluate 

initiation/promotion in rats using a breast cancer 

model (Mevissen et al., 1993) and pineal gland 

function and ornithine decarboxylase activity in rats 

exposed to harmonic fields, 60-Hz fields with 

transients, and intermittent fields. The initiation/ 

promotion breast carcinogenicity studies, which have 

obvious implications for the interpretation of the 

2-year carcinogenicity studies, are reported in NTP 

Technical Report 489 (NTP, 1999). 

 

19 

MATERIALS AND METHODS
 

MAGNETIC FIELD PRODUCTION 

AND MONITORING 

The magnetic field exposure facility consisted of five 

animal exposure rooms, storage rooms, cage washing 

facilities, a necropsy facility, an engineering control 

room for the generation and monitoring of fields and 

room conditions, access corridors, and showers 

and changing rooms for laboratory technicians 

(Figure E1). Offset coils in the exposure rooms and 

in storage rooms between the exposure rooms were 

used to minimize stray fields. The engineering control room contained the generator that produced the 

current that supplied the coils in each exposure room 

and monitors for induced and stray 60-Hz magnetic 

fields and for the collection of humidity, temperature, sound, vibration, ventilation, and light data. 

The engineering control room was outside the range 

of stray magnetic fields above 1 mG. 

Each coil set consisted of seven pairs of rectangular, 

vertically oriented coils connected in series and spaced 

uniformly through the room. The coil sets were 

stacked one above the other; the bottom coils produced a linear 60-Hz magnetic field in one direction 

while the top coils produced a similar field in the 

opposite direction (Figure E2). The coil position in 

each room protected against field overlap between 

rooms. The opposing fields produced by the coil sets 

largely canceled each other outside the area of the 

exposure room. Additional field cancellation was 

provided by horizontally positioned steering coils 

located at the ends of each coil set. Compensating 

capacitors were located between each coil to cancel 

the inductive reactance at 60 Hz and to control the 

voltage differential between adjacent coils. 

Coils were held in place by fiberglass supports and 

were protected from moisture by PlexiglasTM enclosures. DurometerTM neoprene pads between the coils 

and supports isolated coil vibrations. Each coil set 

was controlled from the engineering control room. 

The fields in three rooms had intensities of 0.02, 2, 

and 10 G, and the field in a fourth room was manipulated to produce an intermittent 10-G field (1 hour on 

and 1 hour off). Harmonic distortion was less than 

3%. A fifth room with an identical coil apparatus that 

was not operating served as the control animal exposure room. Fiberglass cage racks were constructed to 

prevent disruption of the induced magnetic fields. 

The stainless steel automatic watering system was 

designed and configured to eliminate possible current 

loops. Fiberglass guides and floor plates were located 

in each room to provide precise alignment of racks 

and cages within the magnetic field. Racks held equal 

numbers of polycarbonate cages in either the top or 

the bottom field of the coil sets (Figure E2). Cages 

were alternated between the top and bottom linear 

horizontal fields on a weekly basis. The field 

uniformity within the cage area was within ± 10% of 

the targeted field intensity (Appendix E). Measurements of field intensities showed that the maximum 

deviations from the target field levels occurred at the 

extreme corners of the cages. 

Induced alternating 60-Hz magnetic fields were monitored by a MultiWaveTM Monitoring System (Electric 

Research and Management, Inc., Pittsburgh, PA), 

which consisted of a microcomputer, an external tiein, and data multiplexors that were located in the 

control room. In animal exposure rooms, monitoring 

system components included a series of three-axis 

alternating-current magnetic field probes (two per 

room), alternating-current voltage probes, and 

environmental sensor probes (to measure rack vibration, noise, light intensity, temperature, and humidity). The magnetic probes, which were located at the 

end of each exposure module in the center of the 

steering coils to detect faults in the coils, allowed 

monitoring of the ambient magnetic fields during 

the “off” periods of intermittent exposure and during 

daily field shutdowns. The computer program 

(WAVE-C) continuously monitored and collected 

sensor data. Data samples were electronically stored 

every 30 minutes, and data were off-loaded from the 

system on a daily basis. The system was equipped 

with alarms to alert project personnel in the event that 

measured parameters deviated from set ranges. 
20 60-Hz Magnetic Fields, NTP TR 488 

Average field intensities measured during the 2-year 

studies are given in Table E1. All daily mean intensities were within 10% of the target; the maximum 

magnetic field intensity in the control animal exposure 

room did not exceed 1.3 mG. There was some variation in the mean magnetic field strengths since the 

field controllers did not tightly regulate line voltage 

from the commercial power grid. These variations 

were on the order of a few percent or less and may be 

similar to what would occur in a residence. The field 

controllers did reduce harmonics and provide protection from over-voltage and brown-outs. The sham 

exposure field intensities were due to field sources 

outside the facility such as distribution lines buried in 

adjacent streets and street lighting circuits. While 

these background fields were variable, the sham exposure fields were nearly always less than 1 mG. The 

groups of animals were rotated from room to room 

every 10 weeks, so each of the five animal exposure 

rooms served as the control exposure room twice during the 2-year study (a final rotation was not carried 

out for the last 4 weeks). This served to minimize 

environmental effects of each room and the variation 

between the earth’s static magnetic fields with different exposure regimens. 

FACILITY VALIDATION 

During a preliminary study, an animal rack equipped 

with eight thermocouples was placed in each animal 

room to record cage temperatures when fields were 

on and off. No differences in temperature were 

found with magnetic field exposures. In addition, the 

exposure system was validated by a representative of 

the National Institute of Standards and Technology 

(NIST), who found that the intensities and spatial 

uniformity of the earth’s static magnetic fields within 

the animal exposure area were consistent with the 

expected intensities in the Chicago area (approximately 300 to 400 mG) (Table E2). Using a NIST 

fluxgate magnetometer, measurements were made 

of the direct-current magnetic field component that 

was parallel to the direction of the alternating-current 

magnetic field in each exposure room in a north-south 

direction. The measurements were performed in the 

top and bottom coil systems at the level of the rat and 

mouse enclosures in each exposure bay. The results 

are presented in Table E3. The calibration uncertainty of the fluxgate magnetometer was estimated to 

be less than 2%; however, the measurements are sensitive to probe alignment because of the nonuniformity 

of the field and the presence of a significant vertical 

magnetic field component. The full NIST validation 

report is presented in Appendix F. 

2-YEAR STUDIES 

Study Design 

Groups of 100 male and 100 female rats and mice 

were exposed to 60-Hz magnetic fields at intensities 

of 0.02, 2, or 10 G for 18.5 hours per day, 7 days 

per week, for 106 weeks. The exposure was continuous for 4 hours (11 a.m. to 3 p.m.), discontinued 

for 1.5 hours (3 p.m. to 4:30 p.m.), continuous for 

14.5 hours (4:30 p.m. to 7 a.m.), and then discontinued for an additional 4 hours (7 a.m. to 11 a.m.). 

Gaps in exposure allowed for animal husbandry and 

observation. Groups of 100 male and 100 female 

control rats and mice were housed in the same 

exposure chambers without applied magnetic fields. 

Groups of 100 male and female rats and mice were 

intermittently exposed (1 hour on and 1 hour off, 

starting at 11 a.m.) to a 10 G 60-Hz field for 

18.5 hours per day, 7 days per week, for 106 weeks, 

with similar 1.5- and 4-hour gaps in exposure. 

Source and Specification of Animals 

Male and female F344/N rats and B6C3F mice were 1 

obtained from Taconic Farms (Germantown, NY). 

Rats were quarantined for 11 or 12 days before the 

beginning of the studies; mice were quarantined for 

13 or 14 days. Five male and five female rats and 

mice were randomly selected for parasite evaluation 

and gross observation of disease. Rats and mice were 

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 H). 

Animal Maintenance 

Rats and female mice were housed five per cage; male 

mice were housed individually. Feed and water were 

available ad libitum. Further details of animal maintenance are given in Table 1. Information on feed composition and contaminants is provided in Appendix G. 
60-Hz Magnetic Fields, NTP TR 488 21 

Clinical Examinations and Pathology 

All animals were observed twice daily. Animals were 

weighed on the first exposure day, weekly through 

week 12, monthly until week 93, and then every 

2 weeks until the end of the study. Clinical observations were recorded monthly. 

A complete necropsy and microscopic examination 

were performed on all 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, processed and trimmed, embedded in paraffin, sectioned 

to a thickness of 4 to 6 μm, and stained with hematoxylin and eosin for microscopic examination. For 

all paired organs (e.g., adrenal gland, kidney, ovary), 

samples from each organ were examined. Recuts of 

tissue are routinely taken if the original section contains an inadequate amount or altered tissue (e.g., 

folds) that may interfere with adequate microscopic 

assessment and interpretation. In this study, the number of tissue recuts that included thyroid gland C-cell 

tissue was higher in some groups than others. This 

small sample bias was corrected by getting recuts of 

thyroid gland C-cell tissue from all male rats for 

which recuts were not originally taken. As a result, 

there were two sections (rarely three) of thyroid gland 

C-cell tissue for each male rat. Tissues examined 

microscopically are listed in Table 1. 

Microscopic evaluations were completed by the 

study laboratory pathologist, and the pathology data 

were entered into the Toxicology Data Management 

System. 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 rat studies, a quality assessment pathologist reviewed the adrenal medulla (males only) and 

mammary gland (females only) for all diagnoses. The 

following were reviewed by a quality assessment 

pathologist for all diagnoses of proliferative lesions 

specific to the site: adrenal cortex, brain, liver, thyroid gland C-cell, and pancreatic islets (males only). 

The pineal gland was reviewed for degeneration, and 

the spleen for hematopoietic cell proliferation (females 

only). The liver and spleen were reviewed for all 

diagnoses of lymphoproliferative neoplasms (including 

histiocytic sarcoma). The following were reviewed by 

a quality assessment pathologist only when the specific diagnoses had been made: kidney necrosis, 

mammary gland fibroadenoma, preputial gland adenoma, carcinoma, and focal hyperplasia, and seminal 

vesicle adenoma in male rats; all skin neoplasms in 

male and female rats; and uterus deciduoma in female 

rats. 

For the 2-year mouse studies, the following were 

reviewed by a quality assessment pathologist for all 

diagnoses of proliferative lesions specific to the site: 

brain, lung, and uterus (females only). The following 

were reviewed for all diagnoses of hematopoietic proliferative neoplasms (including histiocytic sarcoma): 

liver, spleen, thymus, and mesenteric and mandibular 

lymph nodes. The prostate was reviewed for cysts. 

The following were reviewed by a quality assessment 

pathologist only when the specific diagnoses had been 

made: kidney carcinoma, nose sarcoma, prostate 

adenoma and carcinoma, and seminal vesicle adenoma 

and carcinoma in male mice; and nose rhabdomyosarcoma, liver adenoma, and hemangiosarcoma of the 

bone, skeletal muscle, and liver in female mice. 

The quality assessment report and the reviewed slides 

were submitted to the NTP Pathology Working Group 

(PWG) chairperson, who reviewed selected tissues 

and addressed any inconsistencies in the diagnoses 

made by the laboratory and quality assessment pathologists. Representative histopathology 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 presented by 

the chairperson to the PWG for review. The PWG 

consisted of the quality assessment pathologist and 

other pathologists experienced in rodent toxicologic 

pathology. This group examined the tissues without 

any knowledge of dose groups or previously rendered 

diagnoses. 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 laboratory pathologists, 

reviewing pathologist(s), and the PWG. Details of 

these review procedures have been described, in part, 
22 60-Hz Magnetic Fields, NTP TR 488 

by Maronpot and Boorman (1982) and Boorman et al. lesions for each tissue type separately or combined 

(1985). For subsequent analyses of the pathology was generally based on the guidelines of McConnell 

data, the decision of whether to evaluate the diagnosed et al. (1986). 

TABLE 1 

Experimental Design and Materials and Methods in the 2-Year Whole-Body Exposure Studies 

of 60-Hz Magnetic Fields 

Study Laboratory 

IIT Research Institute (Chicago, IL) 

Strain and Species 

Rats: F344/N 

Mice: B6C3F1 

Animal Source 

Taconic Farms (Germantown, NY) 

Time Held Before Studies 

Rats: 11-12 days 

Mice: 13-14 days 

Average Age When Studies Began 

6-7 weeks 

Date of First Exposure 

Because of the size of study groups, there were two cohorts each for male and female rats and mice. 

Rats: 26 September or 17 October 1994 (males) 

27 September or 18 October 1994 (females) 

Mice: 5 or 26 October 1994 (males) 

6 or 27 October 1994 (females) 

Duration of Exposure 

18.5 hours per day, 7 days per week, for 106 weeks 

Date of Last Exposure 

Rats: 1 or 23 October 1996 (males) 

4 or 25 October 1996 (females) 

Mice: 9 or 30 October 1996 (males) 

11 October 1996 or 1 November 1996 (females) 

Necropsy Dates 

Rats: 30 September and 1 October 1996 or 21-23 October 1996 (males) 

2-4 October 1996 or 23-25 October 1996 (females) 

Mice: 7-9 October 1996 or 28-30 October 1996 (males) 

9-11 October 1996 or 30 October-1 November 1996 (females) 

Average Age at Necropsy 

112-113 weeks 

Size of Study Groups 

100 males and 100 females 

Method of Distribution 

Animals were distributed randomly into groups of approximately equal initial mean body weights. 
60-Hz Magnetic Fields, NTP TR 488 23 

TABLE 1 

Experimental Design and Materials and Methods in the 2-Year Whole-Body Exposure Studies 

of 60-Hz Magnetic Fields 

Animals per Cage 

5 (rats and female mice) 

1 (male mice) 

Method of Animal Identification 

Tail tattoo 

Diet 

NTP-2000 open formula pelleted diet (Zeigler Brothers, Inc., Gardners, PA), available ad libitum, changed daily 

Water 

Tap water (Chicago municipal supply) via automatic watering system (SE Lab group, Cincinnati, OH), available ad libitum 

Cages 

Polycarbonate (Lab Products Inc., Maywood, NJ), changed twice weekly (rats and female mice) or once weekly (male mice) 

Bedding 

Beta-Chips® (Northeastern Products Corp., Warrensburg, NY), changed twice weekly (rats and female mice) or once weekly (male mice) 

Cage Filters 

Flat non-woven sheets (Lab Products Inc., Maywood, NJ), changed every 2 weeks 

Racks 

Fiberglass (fabricated on site), cages rotated in racks twice weekly, racks rotated within room once weekly, and exposure groups rotated 

between exposure rooms every 10 weeks, except before the final 4 weeks 

Animal Room Environment 

Temperature: 21.5E-23.4E C 

Relative humidity: 37%-61% 

Room fluorescent light: 12 hours/day 

Room air changes: 10/hour 

Exposure Levels 

Continuous exposure: 0, 0.02, 2, or 10 G, 18.5 hours per day, 7 days per week 

Intermittent exposure: 10 G (1 hour on and 1 hour off), 18.5 hours per day, 7 days per week 

Type and Frequency of Observation 

Observed twice daily; animals were weighed on the first exposure day, weekly through week 12, monthly until week 93, and then every 2 weeks 

until the end of the study; clinical observations were recorded monthly. 

Method of Sacrifice 

CO2 asphyxiation 

Necropsy 

Necropsy was performed on all animals. 

Histopathology 

Complete histopathologic examinations were performed on all rats and mice. In addition to gross lesions and tissue masses, the tissues 

examined included: adrenal gland, bone with marrow, brain, clitoral gland, esophagus, gallbladder (mice), harderian gland, heart with aorta, 

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

mesenteric), mammary gland (except male mice), nose, ovary, pancreas, parathyroid gland, pineal gland, pituitary gland, preputial gland, 

prostate gland, salivary gland, spleen, stomach (forestomach and glandular), testis with epididymis and seminal vesicle, thymus, thyroid gland, 

trachea, urinary bladder, and uterus. 
24 60-Hz Magnetic Fields, NTP TR 488 

STATISTICAL METHODS 

Survival Analyses 

The probability of survival was estimated by the 

product-limit procedure of Kaplan and Meier (1958) 

and is presented in the form of graphs. Animals 

found dead of other than natural causes or removed 

from the study for other reasons were censored from 

the survival analyses; animals dying from natural 

causes were not censored. Statistical analyses for 

possible dose-related effects on survival used Cox’s 

(1972) method for testing two groups for equality and 

Tarone’s (1975) life table test to identify dose-related 

trends. All reported P values for the survival analyses 

are two sided. 

Calculation of Incidence 

The incidences of neoplasms or nonneoplastic lesions 

are presented in Tables A1, A3, B1, B3, C1, C3, D1, 

and D3 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 neoplasms (Tables A2, B2, C2, and D2) and all 

nonneoplastic lesions are given as the numbers of 

animals affected at each site examined microscopically. However, when macroscopic examination was 

required to detect neoplasms in certain tissues (e.g., 

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 survival-adjusted 

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, to 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 procedure 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. 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 site-specific lesions. This value was 

recommended by Bailer and Portier (1988) following 

an evaluation of neoplasm onset time distributions for 

a variety of site-specific neoplasms 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 

overall exposure-related trend. Continuity-corrected 

tests were used in the analysis of lesion incidence, and 

reported P values are one sided. Values of P greater 

than 0.5 are presented as 1–P with the letter N added 

to indicate a lower incidence or negative trend in 

neoplasm occurrence relative to the control group 

(e.g., P=0.99 is presented as P=0.01N). 

QUALITY ASSURANCE METHODS 

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 
60-Hz Magnetic Fields, NTP TR 488 25 

retrospectively by an independent quality assurance 

contractor. Separate audits covered completeness and 

accuracy of the pathology data, pathology specimens, 

final pathology tables, and a draft of this NTP 

Technical Report. Audit procedures and findings are 

presented in the reports and are on file at the National 

Institute of Environmental Health Sciences. The audit 

findings were reviewed and assessed by NTP staff, 

and all comments were resolved or addressed during 

the preparation of this Technical Report. 
26 60-Hz Magnetic Fields, NTP TR 488 

 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

27 

RESULTS
 

RATS 

2-YEAR STUDY 

Survival	 Body Weights and Clinical Findings 

Estimates of 2-year survival probabilities for male Mean body weights of exposed groups of male and 

and female rats are shown in Table 2 and in the female rats were similar to those of the control groups 

Kaplan-Meier survival curves (Figure 1). Survival of throughout the study (Figure 2; Tables 3 and 4). 

exposed rats was similar to that of control rats. There were no exposure-related clinical findings. 

TABLE 2 

Survival of Rats in the 2-Year Whole-Body Exposure Study of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Male 

Animals initially in study	 100 100 100 100 100 

Othera 0 1 0 0 1 

Moribund 29 32 32 36 33 

Natural deaths 14 21 21 16 7 

Animals surviving to study termination 57 46 47 48 59 

Percent probability of survival at end of studyb 57 47 47 48 60 

Mean survival (days)c 692 678 684 675 688 

Survival analysisd	 P=0.583e P=0.197 P=0.282 P=0.244 P=0.923N 

Female 

Animals initially in study	 100 100 100 100 100 

Othera 1 0 0 1 0 

Moribund 22 15 22 19 23 

Natural deaths 18 17 18 19 19 

f g	 g Animals surviving to study termination 59 68 60 61 58 

Percent probability of survival at end of study 60 68 60 62 58 

Mean survival (days) 692 705 697 686 684 

Survival analysis	 P=0.988 P=0.244N P=0.884N P=0.719N P=0.877 

a Censored from survival analyses b	 Kaplan-Meier determinations 

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 lower mortality in an exposure group is indicated by N. e Intermittent group not included in trend test analysis f	 Includes one animal that died during the last week of the study 

g	 Includes two animals that died or were sacrificed moribund during the last week of the study 

c 
28 60-HZ Magnetic Fields, NTP TR 488 


FIGURE 1


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

60-HZ Magnetic Fields for 2 Years
 
60-HZ Magnetic Fields, NTP TR 488 
 29 

FIGURE 2


Growth Curves for Male and Female Rats Exposed to 60-HZ Magnetic
 

Fields for 2 Years
 
30 60-Hz Magnetic Fields, NTP TR 488 

TABLE 3 

Mean Body Weights and Survival of Male Rats in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Weeks Control 0.02 G 2 G 

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 

1 107 100 106 99 100 106 99 100 

2 138 100 138 100 100 138 100 100 

3 173 100 173 100 100 173 100 100 

4 202 100 202 100 100 203 101 100 

5 228 100 227 100 100 230 101 100 

6 250 100 249 100 100 250 100 100 

7 267 100 267 100 100 268 100 100 

8 286 100 284 99 100 285 100 100 

9 301 100 299 100 100 302 101 100 

10 315 100 312 99 100 316 100 100 

11 327 100 324 99 100 328 100 100 

12 337 100 333 99 100 339 101 100 

13 347 100 343 99 100 349 101 100 

17 375 100 371 99 100 380 101 100 

21 398 100 394 99 100 404 102 100 

25 417 100 415 100 100 425 102 100 

29 433 100 433 100 100 440 102 100 

33 448 100 448 100 100 454 101 100 

37 459 100 461 101 100 464 101 100 

41 467 100 472 101 99 472 101 100 

45 476 99 479 101 99 482 101 100 

49 482 99 482 100 98 487 101 100 

53 485 99 485 100 98 491 101 100 

57 488 99 487 100 98 492 101 100 

61 491 98 490 100 97 498 102 98 

65 494 98 493 100 97 500 101 98 

69 495 97 493 100 95 501 101 97 

73 493 96 496 101 94 501 102 93 

77 492 95 494 100 92 498 101 92 

81 491 94 496 101 87 498 101 89 

85 491 90 494 101 86 498 102 85 

89 483 88 498 103 78 496 103 82 

93 485 82 494 102 73 488 101 79 

95 486 77 493 101 71 487 100 75 

97 491 73 488 99 69 489 100 72 

99 493 71 485 98 64 485 98 71 

101 484 65 475 98 62 479 99 65 

103 488 60 469 96 58 476 98 64 

105 484 58 467 96 51 473 98 53 

Mean for weeks 

1-13 252 251 100 253 100 

14-52 439 439 100 445 101 

53-105 489 488 100 491 100 
60-Hz Magnetic Fields, NTP TR 488 31 

TABLE 3 

Mean Body Weights and Survival of Male Rats in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Weeks 10 G 10 G Intermittent 

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

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

1 105 99 100 106 99 100 

2 139 101 100 139 101 100 

3 173 100 100 172 100 100 

4 203 101 100 202 100 100 

5 228 100 100 227 100 100 

6 250 100 100 249 100 100 

7 268 100 100 266 100 100 

8 285 100 100 285 100 100 

9 301 100 100 300 100 100 

10 316 100 100 313 99 100 

11 327 100 100 326 100 100 

12 338 100 100 337 100 100 

13 347 100 100 345 100 100 

17 375 100 100 373 99 100 

21 397 100 100 396 100 100 

25 420 101 100 420 101 100 

29 439 102 100 437 101 100 

33 452 101 100 450 101 100 

37 465 101 100 462 101 100 

41 476 102 100 470 101 100 

45 482 101 100 475 100 99 

49 486 101 100 480 100 99 

53 489 101 100 483 100 99 

57 489 100 100 488 100 98 

61 492 100 99 492 100 98 

65 499 101 97 497 101 98 

69 502 101 96 502 101 97 

73 502 102 90 501 102 96 

77 505 103 87 495 101 95 

81 499 102 86 493 101 88 

85 502 102 82 499 102 81 

89 502 104 77 495 102 78 

93 497 102 76 488 101 76 

95 498 102 73 492 101 74 

97 496 101 68 485 99 73 

99 498 101 64 487 99 70 

101 488 101 62 481 100 68 

103 486 100 59 472 97 66 

105 476 98 53 478 99 59 

Mean for weeks 

1-13 252 100 251 100 

14-52 444 101 440 100 

53-105 495 101 489 100 
32 60-Hz Magnetic Fields, NTP TR 488 

TABLE 4 

Mean Body Weights and Survival of Female Rats in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Weeks Control 0.02 G 2 G 

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 97 100 97 100 100 97 100 100 

2 116 100 116 101 100 115 100 100 

3 131 100 133 101 100 131 100 100 

4 144 100 145 101 100 144 100 100 

5 154 100 155 101 100 155 100 100 

6 164 100 165 100 100 163 100 100 

7 172 100 172 100 100 171 99 100 

8 178 100 178 100 100 177 100 100 

9 184 100 184 100 100 182 99 100 

10 190 100 190 100 100 189 99 100 

11 195 100 194 99 100 194 99 100 

12 199 100 199 100 100 200 100 100 

13 203 100 202 99 100 204 100 100 

17 213 100 213 100 100 219 103 100 

21 223 100 222 100 100 227 102 100 

25 232 100 233 100 100 234 101 100 

29 240 100 240 100 100 242 101 100 

33 248 100 249 101 100 249 101 100 

37 255 100 259 102 100 256 100 100 

41 264 100 268 102 100 266 101 100 

45 272 100 276 101 100 275 101 100 

49 279 100 282 101 100 282 101 100 

53 285 100 289 101 100 289 101 99 

57 292 100 297 102 100 296 102 99 

61 299 100 303 102 100 304 102 99 

65 307 100 311 101 100 313 102 98 

69 315 99 317 101 100 319 101 98 

73 320 97 322 101 99 325 102 95 

77 323 96 327 101 96 329 102 94 

81 324 92 328 101 96 330 102 92 

85 327 90 333 102 92 333 102 92 

89 326 82 337 103 88 334 103 90 

93 330 78 338 103 84 332 101 84 

95 330 76 336 102 84 334 101 80 

97 330 74 337 102 80 333 101 78 

99 332 70 340 102 75 336 101 73 

101 331 66 341 103 74 334 101 70 

103 330 64 339 103 73 338 102 66 

105 326 61 340 104 69 338 104 62 

Mean for weeks 

1-13 164 164 100 163 99 

14-52 247 249 101 250 101 

53-105 319 326 102 325 102 
60-Hz Magnetic Fields, NTP TR 488 33 

TABLE 4 

Mean Body Weights and Survival of Female Rats in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Weeks 10 G 10 G Intermittent 

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

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

1 93 96 100 97 100 100 

2 115 100 100 117 101 100 

3 132 100 100 132 101 100 

4 144 100 100 145 101 100 

5 154 100 100 156 101 100 

6 163 99 100 164 100 100 

7 171 99 100 172 100 100 

8 177 99 100 179 101 100 

9 182 99 100 185 100 100 

10 189 99 100 191 100 100 

11 194 99 100 196 101 100 

12 198 99 100 201 101 100 

13 201 99 100 204 100 100 

17 212 100 100 217 102 100 

21 223 100 99 228 102 100 

25 234 101 98 239 103 100 

29 242 101 98 247 103 100 

33 249 101 98 253 102 100 

37 258 101 97 261 102 100 

41 268 102 97 269 102 100 

45 275 101 97 276 102 100 

49 282 101 97 283 102 100 

53 287 101 97 288 101 100 

57 296 102 96 296 102 100 

61 304 102 94 303 101 100 

65 313 102 93 312 102 95 

69 319 101 93 319 101 94 

73 323 101 92 324 101 93 

77 328 102 91 326 101 90 

81 332 102 86 326 100 88 

85 334 102 85 328 101 86 

89 338 104 84 330 101 82 

93 335 102 83 333 101 75 

95 336 102 80 335 101 72 

97 333 101 78 333 101 71 

99 335 101 75 334 101 71 

101 333 101 73 335 101 70 

103 329 100 70 336 102 64 

105 325 100 66 337 103 61 

Mean for weeks 

1-13 163 99 165 101 

14-52 249 101 253 102 

53-105 324 102 323 101 
34 60-Hz Magnetic Fields, NTP TR 488 

Pathology and Statistical Analyses 

This section describes the incidences of neoplasms 

and/or nonneoplastic lesions of the thyroid gland, 

skin, mammary gland, and brain and incidences of 

mononuclear cell leukemia. Summaries of the incidences of neoplasms and nonneoplastic lesions and 

statistical analyses of primary neoplasms that occurred 

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

group are presented in Appendix A for male rats and 

Appendix B for female rats. 

Thyroid Gland (C-cell): Incidences of adenoma and 

carcinoma in male rats exposed to 0.02 G and of 

adenoma in 2 G male rats were significantly greater 

than in the control group (Tables 5 and A2). The 

incidences of adenoma or carcinoma (combined) were 

significantly greater in males exposed to 0.02 or 2 G 

than in the controls. Incidences of hyperplasia in 

exposed groups of male rats were similar to that in 

controls (Tables 5 and A3). Incidences of neoplasms 

in exposed groups of female rats were similar to those 

in controls (adenoma: control, 15/100; 0.02 G, 

20/100; 2 G, 19/100; 10 G, 20/100; 10 G intermittent, 16/100; carcinoma: 5/100, 3/100, 3/100, 

3/100, 6/100; Table B2). 

C-cells (calcitonin-producing cells) are located between the follicular epithelium and the basement 

membrane of the thyroid follicle. As rats age, there 

is an increase in the number of these pale-staining 

C-cells which may be diffuse throughout the thyroid 

gland, but often there is focal proliferation of C-cells 

which may distort and eventually fill the thyroid follicle. Because essentially all aging rats have some 

increase in the number of C-cells, C-cell hyperplasia 

was diagnosed when this was a prominent feature in 

the thyroid gland. Focal C-cell hyperplasia is difficult 

to distinguish from C-cell adenoma. Because the 

lesion can progress from diffuse and focal hyperplasia 

to obvious neoplasia, the criteria used to separate 

hyperplasia from adenoma are subjective. Sometimes 

hyperplasia and adenoma differ only in the relative 

size of the lesion. Focal proliferative lesions smaller 

than five follicles in diameter are designated as focal 

C-cell hyperplasia, and masses larger than this are 

considered to be neoplasms. Cellular atypia, when 

present, can help distinguish C-cell hyperplasia from 

C-cell adenoma. In this study, a reviewing pathologist reviewed all proliferative C-cell lesions to provide consistency in applying the criteria. The C-cell 

adenomas in this study were often small, but a few 

C-cell adenomas filled nearly an entire lobe, and 

occasional C-cell adenomas were bilateral (occurring 

in both lobes of the gland). Because of the microscopic nature of C-cell hyperplasia and C-cell adenoma, they are often found in one histologic section but 

may not be seen on a subsequent section of the same 

gland. C-cell carcinomas consist of solid to irregular 

groups of neoplastic cells similar to those found in the 

C-cell adenoma. Size and invasion are important criteria. C-cell carcinomas usually involved the entire 

lobe of the thyroid gland. C-cell carcinomas often 

showed invasion of the thyroid capsule and in two 

cases had metastasized to the lung. The larger C-cell 

carcinomas show more cellular atypia. In contrast to 

C-cell neoplasms in humans, amyloid is rarely found 

in the rat and was not seen in this study. Because 

of their size, C-cell carcinomas are less subject to 

sectioning and usually appear on all sections of the 

thyroid gland. 
35 

c 

60-Hz Magnetic Fields, NTP TR 488 

TABLE 5 

Incidences of Neoplasms and Nonneoplastic Lesions of the Thyroid Gland (C-Cells) in Male Rats 

in the 2-Year Whole-Body Exposure Study of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Number Examined Microscopically 99 100 100 100 100 

Hyperplasia (includes bilateral)a 33 (1.9)b 23 (2.3) 27 (2.2) 26 (1.9) 33 (2.1) 

Adenoma 

Overall ratec 15/99 (15%) 25/100 (25%) 26/100 (26%) 23/100 (23%) 18/100 (18%) 

Adjusted rated 17.2% 30.0% 30.5% 27.4% 21.5% 

Terminal ratee 7/57 (12%) 15/46 (33%) 16/47 (34%) 13/48 (27%) 16/59 (27%) 

First incidence (days) 583 589 604 561 725 

Poly-3 testf P=0.326 P=0.035 P=0.028 P=0.075 P=0.305 

Carcinoma 

Overall rate 1/99 (1%) 7/100 (7%) 4/100 (4%) 2/100 (2%) 5/100 (5%) 

Adjusted rate 1.2% 8.5% 4.8% 2.5% 5.9% 

Terminal rate 1/57 (2%) 2/46 (4%) 2/47 (4%) 2/48 (4%) 4/59 (7%) 

First incidence (days) 736 (T) 619 687 736 (T) 666 

Poly-3 test P=0.280N P=0.030 P=0.177 P=0.483 P=0.103 

Adenoma or Carcinoma 

Overall rate 16/99 (16%) 31/100 (31%) 30/100 (30%) 25/100 (25%) 22/100 (22%) 

Adjusted rate 18.4% 36.8% 35.1% 29.8% 26.1% 

Terminal rate 8/57 (14%) 17/46 (37%) 18/47 (38%) 15/48 (31%) 19/59 (32%) 

First incidence (days) 583 589 604 561 666 

Poly-3 test P=0.438 P=0.005 P=0.009 P=0.055 P=0.147 

(T)Terminal sacrifice 

a Number of animals with lesion 

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

Number of animals with neoplasm per number of animals with thyroid gland examined microscopically d Poly-3 estimated neoplasm incidence after adjustment for intercurrent mortality e Observed incidence at terminal kill 

f Beneath the control incidence are the P values associated with the trend test; the trend does not include the 10 G intermittent group. 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 negative trend is indicated by N. 

Skin: The incidence of trichoepithelioma was in- Mammary Gland: The incidences of fibroadenoma 

creased in the 10 G male group (0/100, 1/100, 0/100, and carcinoma in exposed groups of male and female 

5/100, 0/100; Table A2). This increase was not seen rats were similar to those in the control groups 

for other neoplasms of basal cell origin such as basal (Tables 6, A1, and B1). The incidences of epithelial 

cell adenoma, keratoacanthoma, or the group of all hyperplasia in males occurred with a negative trend 

skin neoplasms (combined) (Tables A1 and A2). (Tables 6 and A3). Incidences of epithelial hyperplasia in exposed groups of female rats were similar 

to that in the control group (Tables 6 and B3). 
 

36 60-Hz Magnetic Fields, NTP TR 488 

TABLE 6 

Incidences of Neoplasms and Nonneoplastic Lesions of the Mammary Gland in Rats 

in the 2-Year Whole-Body Exposure Study of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Male 

Number Examined Microscopically 

Epithelial Hyperplasiaa 99 9 (1.4)b 

97 

1* (2.0) 

100 

4 (2.3) 

98 

3 (1.7) 

95 

4 (1.8) 

Fibroadenoma 

Carcinoma 

6 

0 

6 

1 

11 

0 

9 

0 

8 

0 

Female 

Number Examined Microscopically 

Epithelial Hyperplasia 

100 

1 (3.0) 

100 

4 (2.5) 

100 

3 (1.7) 

100 

2 (2.0) 

100 

3 (2.0) 

Fibroadenoma 

Carcinoma 

56 

2 

62 

7 

54 

5 

64 

2 

51 

2 

* Significantly different (P#0.05) from the control group by the Poly-3 test a Number of animals with lesion 

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

Brain: Astrocytoma was observed in one male and Mononuclear Cell Leukemia: The incidence of 

one female in the control groups and in two females mononuclear cell leukemia in males in the 10 G interexposed to 10 G (Tables A1 and B1). Oligodendro- mittent group was significantly less (P=0.045) than 

glioma was observed in one control male rat and one that in the control group (50/100, 44/100, 47/100, 

male rat in the 10 G intermittent group (Table A1). In 50/100, 36/100; Table A2). Incidences of mononufemale rats, glioma was observed in one control rat clear cell leukemia in exposed groups of female rats 

(Table B1), and focal gliosis was observed in one rat were similar to that in the control group (20/100, 

in the 10 G intermittent group (Table B3). The 18/100, 24/100, 25/100, 22/100; Table B2). 

incidence of brain neoplasms was not affected by 

exposure to magnetic fields. 
	 

	 

	 

	 

	 

	 

	 

37 

c 

60-Hz Magnetic Fields, NTP TR 488 

M that of control mice; survival of all other exposed ICE groups of mice was similar to that of control mice.

2-YEAR STUDY 

Survival	 Body Weights and Clinical Findings 

Estimates of 2-year survival probabilities for male Mean body weights of exposed groups of male and 

and female mice are shown in Table 7 and in the female mice were similar to those of the control 

Kaplan-Meier survival curves (Figure 3). Survival of groups throughout the study (Figure 4; Tables 8 and 

male mice exposed to 10 G was significantly less than 9). There were no exposure-related clinical findings. 

TABLE 7 

Survival of Mice in the 2-Year Whole-Body Exposure Study of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Male 

Animals initially in study	 100 100 100 100 100 

Moribund 11 13 6 15 8 

Natural deaths 13 15 10 23 18 

Animals surviving to study termination 76 72 84 62 74d 

Percent probability of survival at end of studya 76 72 84 62 74 

Mean survival (days)b 711 698 712 687 703 

c	 e Survival analysis	 P=0.011 P=0.540 P=0.248N P=0.037 P=0.783 

Female 

Animals initially in study	 100 100 100 100 100 

Accidental deathsf 1 1 2 1 0 

Moribund 6 7 6 7 8 

Natural deaths 23 18 13 18 15 

Animals surviving to study termination 70d 74 79 74 77 

Percent probability of survival at end of study 71 75 81 75 77 

Mean survival (days) 702 700 700 696 704 

Survival analysis	 P=0.967N P=0.674N P=0.185N P=0.676N P=0.490N 

a Kaplan-Meier determinations b	 Mean of all deaths (uncensored, censored, and terminal sacrifice) 

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 exposure group is indicated by N. d	 Includes one animal that died during the last week of the study e Intermittent group not included in trend test analysis f Censored from survival analysis 
38 60-HZ Magnetic Fields, NTP TR 488 


FIGURE 3


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

60-HZ Magnetic Fields for 2 Years
 
60-HZ Magnetic Fields, NTP TR 488 
 39 

FIGURE 4


Growth Curves for Male and Female Mice Exposed to 60-HZ Magnetic
 

Fields for 2 Years
 
40 60-Hz Magnetic Fields, NTP TR 488 

TABLE 8 

Mean Body Weights and Survival of Male Mice in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Weeks Control 0.02 G 2 G 

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 23.8 100 23.6 99 100 24.1 101 100 

2 24.4 100 23.6 97 100 24.5 100 100 

3 26.6 100 26.3 99 100 26.6 100 100 

4 28.1 100 27.8 99 100 28.0 100 100 

5 29.5 100 29.3 99 100 29.3 99 100 

6 31.4 100 30.8 98 100 30.8 98 100 

7 32.9 100 32.4 99 100 32.5 99 100 

8 34.5 100 33.9 98 100 34.3 99 100 

9 36.2 100 35.5 98 100 35.5 98 100 

10 37.5 100 37.0 99 100 36.8 98 100 

11 39.0 100 38.2 98 100 38.3 98 100 

12 40.2 100 39.7 99 100 39.7 99 100 

13 41.0 100 40.5 99 100 40.8 100 100 

17 44.7 100 44.7 100 100 45.0 101 100 

21 47.2 100 47.1 100 100 47.2 100 100 

25 47.8 100 48.2 101 100 47.9 100 100 

29 48.5 100 49.0 101 100 48.6 100 100 

33 49.7 100 49.7 100 100 49.7 100 100 

37 50.5 100 50.3 100 100 50.1 99 100 

41 51.5 100 51.4 100 100 50.8 99 100 

45 52.3 100 52.1 100 100 50.9 97 100 

49 52.5 100 52.0 99 100 50.9 97 100 

53 52.7 100 51.9 99 100 51.0 97 100 

57 52.4 99 51.4 98 100 50.6 97 100 

61 52.1 99 51.7 99 99 50.9 98 100 

65 52.5 99 51.9 99 99 51.8 99 99 

69 52.7 99 52.3 99 97 52.1 99 98 

73 52.5 98 52.1 99 96 51.4 98 98 

77 51.4 97 51.2 100 95 49.6 97 97 

81 49.3 96 48.3 98 93 46.8 95 95 

85 46.0 93 46.2 100 90 44.8 97 92 

89 44.2 92 45.7 103 85 44.4 101 91 

93 42.6 90 43.5 102 82 43.7 103 88 

95 42.2 89 42.5 101 81 43.3 103 87 

97 41.1 88 42.5 103 78 42.8 104 87 

99 41.6 84 42.4 102 78 42.7 103 87 

101 41.5 83 42.8 103 78 42.3 102 86 

103 40.8 82 41.9 103 76 41.9 103 86 

105 40.8 77 41.5 102 72 41.2 101 84 

Mean for weeks 

1-13 32.7 32.2 98 32.4 99 

14-52 49.4 49.4 100 49.0 99 

53-105 46.8 47.0 100 46.5 99 
60-Hz Magnetic Fields, NTP TR 488 41 

TABLE 8 

Mean Body Weights and Survival of Male Mice in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Weeks 10 G 10 G Intermittent 

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

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

1 24.2 102 100 23.8 100 100 

2 24.0 98 100 24.6 101 100 

3 26.7 100 100 26.5 100 100 

4 28.3 101 100 28.1 100 100 

5 29.4 100 100 29.3 99 100

 6 30.5 97 100 30.7 98 100

 7 32.4 99 100 32.5 99 100 

8 34.3 99 100 34.2 99 100 

9 35.3 98 100 35.6 98 100 

10 36.8 98 100 37.1 99 100 

11 38.0 97 100 38.4 99 100 

12 38.9 97 100 39.8 99 100 

13 40.0 98 100 41.0 100 100 

17 44.4 99 100 45.2 101 100 

21 47.1 100 100 47.6 101 100 

25 48.7 102 100 48.6 102 100 

29 49.9 103 100 49.6 102 100 

33 51.0 103 100 50.1 101 100 

37 51.5 102 100 50.2 99 100 

41 52.5 102 100 51.0 99 100 

45 52.7 101 100 51.6 99 100 

49 52.2 99 100 51.3 98 100 

53 52.2 99 100 50.8 96 100 

57 51.6 99 99 51.1 98 100 

61 51.8 99 99 51.3 99 98 

65 52.4 100 98 51.8 99 98 

69 52.7 100 96 52.5 100 97 

73 52.7 100 93 52.1 99 97 

77 52.0 101 89 51.3 100 96 

81 49.5 100 88 48.4 98 93 

85 46.6 101 86 44.7 97 90 

89 45.1 102 82 43.4 98 89 

93 43.9 103 80 42.6 100 87 

95 42.8 101 80 42.3 100 86 

97 42.7 104 75 42.2 103 81 

99 42.4 102 74 42.5 102 78 

101 41.8 101 72 42.3 102 78 

103 40.2 99 68 41.5 102 76 

105 39.7 97 63 40.5 99 75 

Mean for weeks 

1-13 32.2 98 32.4 99 

14-52 50.0 101 49.5 100 

53-105 47.1 101 46.5 99 
42 60-Hz Magnetic Fields, NTP TR 488 

TABLE 9 

Mean Body Weights and Survival of Female Mice in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Weeks Control 0.02 G 2 G 

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 18.5 100 18.7 101 100 19.5 105 100 

2 20.4 100 20.6 101 100 20.1 99 100 

3 21.9 100 21.8 100 100 21.7 99 100 

4 22.7 100 22.7 100 100 22.6 100 99 

5 23.3 100 23.4 100 100 23.7 102 99 

6 25.2 100 25.0 99 100 25.0 99 99 

7 26.2 100 26.2 100 100 25.9 99 99 

8 28.0 100 27.4 98 100 27.5 98 99 

9 29.1 100 28.7 99 100 29.3 101 98 

10 30.2 100 30.3 100 100 30.3 100 98 

11 31.9 100 31.2 98 99 32.1 101 98 

12 33.4 100 32.7 98 99 33.7 101 98 

13 34.8 100 33.9 97 99 34.8 100 98 

17 39.6 100 39.0 99 99 39.6 100 98 

21 44.2 100 42.8 97 99 44.1 100 98 

25 47.4 100 46.2 98 99 46.6 98 98 

29 49.7 100 49.2 99 99 49.5 100 98 

33 52.0 100 51.7 99 99 52.1 100 98 

37 53.7 100 53.1 99 99 53.4 99 98 

41 56.0 100 55.3 99 99 55.5 99 98 

45 56.9 99 56.4 99 99 56.1 99 98 

49 56.8 98 57.1 101 99 56.4 99 98 

53 57.4 98 57.6 100 99 56.9 99 98 

57 57.9 98 57.5 99 98 57.2 99 98 

61 58.3 97 57.4 99 98 58.3 100 98 

65 58.3 96 57.9 99 98 59.2 102 98 

69 59.5 95 58.6 99 97 59.9 101 97 

73 59.1 95 57.6 98 95 58.6 99 97 

77 57.2 95 56.5 99 93 57.9 101 95 

81 55.7 92 54.8 98 90 55.7 100 95 

85 54.1 92 54.1 100 90 54.4 101 92 

89 53.9 89 54.3 101 89 54.3 101 91 

93 53.3 88 52.9 99 89 52.5 99 90 

95 53.0 88 52.4 99 89 51.6 97 86 

97 52.0 86 52.1 100 84 51.4 99 83 

99 51.8 86 51.1 99 83 51.8 100 83 

101 51.0 82 51.4 101 81 52.1 102 80 

103 50.8 78 50.4 99 79 51.5 101 80 

105 51.5 73 49.8 97 76 51.1 99 79 

Mean for weeks 

1-13 26.6 26.4 99 26.6 100 

14-52 50.7 50.1 99 50.4 99 

53-105 55.0 54.5 99 55.0 100 
60-Hz Magnetic Fields, NTP TR 488 43 

TABLE 9 

Mean Body Weights and Survival of Female Mice in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Weeks 10 G 10 G Intermittent 

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

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

1 19.1 103 100 18.3 99 100 

2 20.7 102 100 20.7 102 100 

3 22.0 101 100 21.8 100 100 

4 22.8 100 100 22.5 99 100 

5 24.1 103 100 23.5 101 100 

6 25.1 100 100 25.1 100 100 

7 26.2 100 100 26.4 101 100 

8 27.5 98 100 27.9 100 100 

9 29.1 100 100 29.2 100 100 

10 30.4 101 100 30.8 102 100 

11 32.1 101 100 32.3 101 100 

12 33.7 101 100 33.7 101 100 

13 34.6 99 100 35.1 101 100 

17 39.9 101 99 39.9 101 100 

21 43.6 99 99 44.4 101 100 

25 47.3 100 99 48.0 101 100 

29 49.6 100 98 50.6 102 100 

33 51.9 100 98 52.3 101 100 

37 53.2 99 98 54.6 102 100 

41 55.6 99 98 55.7 100 100 

45 56.8 100 97 56.8 100 99 

49 57.2 101 97 57.0 100 99 

53 57.6 100 97 57.1 100 99 

57 57.6 100 97 57.8 100 99 

61 57.5 99 97 58.2 100 99 

65 57.6 99 97 59.0 101 99 

69 58.4 98 95 59.5 100 97 

73 58.6 99 93 58.7 99 96 

77 56.7 99 92 56.7 99 96 

81 55.4 100 92 54.5 98 95 

85 54.0 100 89 53.9 100 90 

89 54.0 100 88 53.0 98 89 

93 53.0 99 88 51.1 96 87 

95 52.6 99 87 51.5 97 84 

97 51.4 99 87 50.7 98 84 

99 51.3 99 85 50.5 98 81 

101 51.6 101 81 50.7 99 81 

103 50.7 100 80 50.2 99 78 

105 49.4 96 77 50.0 97 77 

Mean for weeks 

1-13 26.7 100 26.7 100 

14-52 50.6 100 51.0 101 

53-105 54.6 99 54.3 99 
44 60-Hz Magnetic Fields, NTP TR 488 

Pathology and Statistical Analyses 

This section describes the incidences of neoplasms 

and/or nonneoplastic lesions of the lung and mammary gland and incidences of malignant lymphoma. 

Summaries of the incidences of neoplasms and nonneoplastic lesions and statistical analyses of primary 

neoplasms that occurred with an incidence of at least 

5% in at least one animal group are presented in 

Appendix C for male mice and Appendix D for 

female mice. 

Lung: The incidences of alveolar/bronchiolar adenoma were significantly decreased in 0.02 and 2 G male 

mice and 2 G female mice relative to the control 

groups (Tables 10, C2, and D2); the incidences of 

alveolar/bronchiolar adenoma or carcinoma (combined) were significantly less in males and females 

exposed to 2 G than in the control groups. Incidences 

of hyperplasia in exposed groups of male and female 

mice were similar to those in the control groups 

(Tables 10, C3, and D3). 

Mammary Gland: No mammary gland neoplasms 

were observed in male mice. Incidences of adenoma 

or carcinoma in exposed groups of females were 

similar to those in the control group (adenoma: 

control, 0/94; 0.02 G, 0/98; 2 G, 1/99; 10 G, 2/99; 

10 G intermittent, 1/98; carcinoma: 1/94, 0/98, 0/99, 

0/99, 1/98; Table D1). Incidences of hyperplasia 

in exposed groups of male and female mice were 

similar to those in the control groups (Tables C3 

and D3). 

Malignant Lymphoma: The incidences of malignant 

lymphoma in all exposed groups of male mice were 

similar to that in the control group (8/100, 7/100, 

4/100, 7/100, 6/100; Table C2). In female mice, the 

incidence of malignant lymphoma in the 10 G intermittent group was significantly less (P=0.035) than in 

the controls (32/100, 31/100, 22/100, 26/100, 

20/100; Table D2). 
	 

	 

	 

	 

	 

	 

60-Hz Magnetic Fields, NTP TR 488 45 

TABLE 10 

Incidences of Neoplasms and Nonneoplastic Lesions of the Lung in Mice 

in the 2-Year Whole-Body Exposure Study of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Male 

Number Examined Microscopically 

Alveolar Epithelium, Hyperplasia, Focala 100 2 (1.5)b 

99 

2 (1.5) 

100 

0 

99 

3 (2.3) 

99 

2 (2.5) 

Alveolar/bronchiolar Adenoma 

Overall ratec 

Adjusted rated 26/100 (26%) 

28.0% 

11/99 (11%) 

12.5% 

9/100 (9%) 

9.6% 

16/99 (16%) 

18.0% 

16/99 (16%) 

17.9% 

Terminal ratee 22/76 (29%) 10/72 (14%) 7/84 (8%) 7/62 (11%) 15/74 (20%) 

First incidence (days) 

Poly-3 testf 

683 

P=0.470N 

722 

P=0.007N 

585 

P<0.001N 

518 

P=0.077N 

672 

P=0.073N 

Alveolar/bronchiolar Carcinoma 8 11 12 10 10 

Alveolar/bronchiolar Adenoma or Carcinoma 

Overall rate 30/100 (30%) 21/99 (21%) 19/100 (19%) 25/99 (25%) 23/99 (23%) 

Adjusted rate 32.2% 23.7% 20.1% 27.7% 25.6% 

Terminal rate 25/76 (33%) 19/72 (26%) 16/84 (19%) 11/62 (18%) 21/74 (28%) 

First incidence (days) 683 612 430 448 668 

Poly-3 test P=0.495 P=0.130N P=0.041N P=0.302N P=0.203N 

Female 

Number Examined Microscopically 95 100 99 99 100 

Alveolar Epithelium, Hyperplasia, Focal 4 (1.8) 1 (1.0) 2 (2.0) 0 1 (2.0) 

Alveolar/bronchiolar Adenoma 

Overall rate 9/95 (9%) 6/100 (6%) 0/99 (0%) 5/99 (5%) 6/100 (6%) 

Adjusted rate 10.2% 6.6% 0.0% 5.6% 6.6% 

Terminal rate 7/70 (10%) 4/74 (5%) 0/79 (0%) 4/74 (5%) 6/77 (8%) 

First incidence (days) 551 603 —g 566 735 (T) 

Poly-3 test P=0.363N P=0.271N P=0.002N P=0.190N P=0.275N 

Alveolar/bronchiolar Carcinoma 2 6 2 2 1 

Alveolar/bronchiolar Adenoma or Carcinoma 

Overall rate 11/95 (12%) 11/100 (11%) 2/99 (2%) 7/99 (7%) 7/100 (7%) 

Adjusted rate 12.5% 11.9% 2.2% 7.8% 7.7% 

Terminal rate 7/70 (10%) 7/74 (10%) 2/79 (3%) 5/74 (7%) 6/77 (8%) 

First incidence (days) 551 496 735 (T) 566 656 

Poly-3 test P=0.246N P=0.544N P=0.008N P=0.213N P=0.208N 

(T)Terminal sacrifice 

a	 Number of animals with lesion 

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

Number of animals with neoplasm per number of animals with lung examined microscopically d	 Poly-3 estimated neoplasm incidence after adjustment for intercurrent mortality e	 Observed incidence at terminal kill 

f	 Beneath the control incidence are the P values associated with the trend test; the trend does not include the 10 G intermittent group. 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 negative trend or a lower incidence in an 

exposure group is indicated by N. g	 Not applicable; no neoplasms in animal group 

c 
46 60-Hz Magnetic Fields, NTP TR 488 
 


 

47 

DISCUSSION AND CONCLUSIONS
 

The NTP evaluated 60-Hz magnetic field exposures in 

rodent studies after two epidemiology studies suggested that children living in homes expected to have 

higher magnetic field intensities were at increased risk 

for childhood leukemia (Wertheimer and Leeper, 

1979; Savitz et al., 1988). Both the Department of 

Energy and the Electric Power Research Institute 

supported the concept of carefully controlled longterm rodent studies to determine if the normal pattern 

or incidence of cancer that occurs in aging rodents 

would be affected by exposure to 60-Hz (power line 

frequency) magnetic fields. 

At the time of the NTP protocol design, extensive 

characterization of the electric and magnetic fields 

occurring in the home was lacking. The epidemiology 

studies had classified the childhood residences using 

wiring codes as surrogates for predicted magnetic 

fields within the home (Barnes et al., 1989). Because 

electric fields can be easily shielded, and several 

animal studies showed little toxicity with electric 

fields (Leung et al., 1990; Rommereim et al., 1990), 

the greatest concern was with magnetic field exposure. However, residential magnetic fields are quite 

complex; they include not only the 60-Hz frequency 

but also harmonics of the 60-Hz frequency (120 Hz, 

180 Hz, etc.), transients, and other frequencies from 

household appliances. Furthermore, it was not known 

what might be the important exposure parameter: 

frequency, field intensity, change in field intensity, 

time above a certain intensity, or even the wave form. 

Thus, the challenge was to develop a protocol to 

evaluate a complex physical agent for which little was 

known. 

The NTP developed a protocol which was then circulated for comment to more than 80 scientists familiar 

with toxicology studies and magnetic field exposure. It was apparent during study development that 

only a limited number of exposure parameters could 

be evaluated. Because the predominant residential 

exposure in the United States is to 60-Hz fields, only 

this frequency was included. Given the complexity of 

transients and different wave forms, it was decided to 

evaluate 60-Hz sine-wave magnetic fields without 

transients. The maximum feasible field intensity that 

could be evaluated was 10 G, above which vibrations, 

sound, and heat could become confounding factors. 

Because 10-G magnetic fields were nearly 5,000-fold 

greater than most residential exposures, this was 

considered an adequate challenge. The two lower 

magnetic field intensities, 0.02 and 2 G, were chosen 

because the induced currents in rats are about 

10 times less than in human models (Anderson, 1991; 

Miller, 1991). This suggested that the lowest field 

intensity used in rodents might mimic high human 

residential exposures. To explore the possibility that 

a change in field intensity might be more important 

than continuous magnetic field exposure, another 

group of animals was exposed to magnetic fields that 

were switched on and off at 1-hour intervals. To 

enhance sensitivity for detecting small changes in 

neoplasm incidences, 100 animals were used in each 

group rather than the usual 50. The final protocol 

was reviewed by more than a dozen scientists at a 

meeting at the NIEHS prior to the start of the studies. 

The studies were preceded by 8-week whole-body 

exposure studies in F344/N rats and B6C3F1 mice. 

There was no evidence of toxicity or clinical findings 

with exposures up to 10 G (NTP, 1996; Boorman 

et al., 1997), or of developmental toxicity in a subsequent study in female Sprague-Dawley rats (Ryan 

et al., 1996). Further, as part of a Congressional 

mandate for accelerated electromagnetic field (EMF) 

research (EMF RAPID Program), B6C3F mice were 1 

evaluated for evidence of immunotoxicity at the same 

field intensities as in the 8-week studies. In these 

studies, there was no evidence of cellular alterations 

or host immune response (House et al., 1996), or of 

alterations in reproductive parameters in a 6-month 

continuous breeding study in Sprague-Dawley rats 

(Ryan et al., 1999). 

Care was taken to ensure that the groups were as free 

from confounding factors as possible during exposure. 

This treatment included randomization of the animals, 

housing the animals in five rooms with identical 

magnetic field exposure capabilities, weekly cage and 

rack rotations, and room rotation every 10 weeks. 
48 60-Hz Magnetic Fields, NTP TR 488 

Room rotation assured that each group spent 10 weeks 

in each of the five rooms during the first 50 weeks 

and again for the second 50 weeks. The rooms were 

continuously monitored for sound, light, humidity, 

temperature, vibration, and magnetic fields. The 

magnetic fields were characterized by the National 

Institute for Standards and Technology (NIST; 

Appendix F) prior to the beginning of the studies, 

after 1 year, and at the completion of the 2-year 

studies. The earth’s static magnetic fields in the 

rooms were also measured by the study contractor and 

verified by NIST. 

Despite many physiologic differences between rodents 

and humans, there is good correlation between known 

or suspected human carcinogens and test results in 

rodent studies, often with the same organ system 

being affected in rodents as in humans (Wilbourn 

et al., 1986). In the results section of this Technical 

Report, emphasis is placed on the analysis of cancers 

that have been reported to be associated with magnetic 

field exposure in humans. 

Childhood leukemia has been considered a potential consequence of EMF exposure because of the 

initial reports of magnetic field-associated leukemia 

(Wertheimer and Leeper, 1979; Savitz et al., 1988), 

but associations with childhood leukemia have also 

been reported more recently (London et al., 1991; 

Feychting and Ahlbom, 1993). In addition, adult 

occupational exposures associated with increased incidences of leukemia have been reported (Floderus 

et al., 1994; London et al., 1994). However, Linet 

et al. (1997) failed to find an association between 

increased childhood leukemia and residential wire 

codes or measured magnetic fields. In another report, 

static magnetic fields did not enhance the development 

of spontaneous lymphoblastic leukemia in female 

AKR mice (Bellosi, 1986). In the present rodent 

study, mice exposed to up to 10 G for 2 years showed 

no increase in the incidences of malignant lymphoma 

or leukemia. In fact, in female mice there was a 

significant decrease in the incidence of malignant 

lymphoma. 

In the present study, there was no exposure-related increase in the incidence of mononuclear cell leukemia 

in male or female rats. The intermittent exposure 

group of male rats actually had a significant decrease 

in the incidence of mononuclear cell leukemia. 

Another study also found that exposure to 60-Hz 

magnetic fields did not alter the clinical progression of 

transplanted mononuclear cell leukemia in Fischer rats 

(Sasser et al., 1996). A study in female F344 rats 

exposed to 60-Hz magnetic fields from 0.02 to 20 G 

from day 20 of gestation with the female offspring 

continuously exposed for up to 2 years also failed to 

show increased incidences of mononuclear cell 

leukemia (Mandeville et al., 1997). Male and female 

F344 rats exposed to 0, 5, or 50 G 50-Hz magnetic 

fields for up to 2 years also failed to show any 

exposure-related alteration in the incidences of 

mononuclear cell leukemia (Yasui et al., 1997). 

Thus, in the long-term rodent studies to date, neither 

F344 rats nor B6C3F1 mice showed increased leukemia or lymphoma rates when exposed to sine-wave 

magnetic fields for up to 2 years. 

The lack of evidence for an increased incidence of 

leukemia associated with magnetic field exposure 

in rodent studies must still be viewed with caution. 

The most common childhood leukemia, with peak 

occurrence between 3 and 5 years of age, is acute 

lymphoblastic leukemia (Robison and Ross, 1995). 

Acute lymphoblastic leukemia is a heterogeneous 

disease including both T-cell and B-cell leukemia. It 

would appear that the F344/N rat mononuclear cell 

leukemia, which is characterized by a large granular 

lymphocyte (Stromberg et al., 1983), may not be a 

good model for predicting the occurrence of acute 

lymphoblastic leukemia in humans. The mouse is 

considered a good rodent model for human leukemias 

(Pattengale, 1994), but most magnetic field studies in 

the mouse do not include prenatal magnetic field 

exposures. One study that included exposures from 

the day before parturition to 2 years of age was conducted in the female F344/N rat (Mandeville et al., 

1997). 

Some studies have reported an association between 

exposure to magnetic fields and increased risk for 

brain cancer (Savitz and Loomis, 1995; Guénel et al., 

1996), while other studies failed to find a significant 

association (Miller et al., 1996; Preston-Martin et al., 

1996). In the present study, brain cancer was rare. 

No glial neoplasms were diagnosed in male or female 

mice in any exposure group. In male rats, three glial 

neoplasms were found, two in the control group and 

one in the intermittent exposure group. In female 

rats, four glial neoplasms were found, two in the control group and two in the 10 G group. Glial tumors 

were also rare in the study by Yasui et al. (1997), one 
60-Hz Magnetic Fields, NTP TR 488 49 

being found in the 50 G male rat group and one in the 

female 5 G group. There was also no increase in the 

number of glial tumors in rats exposed during the 

prenatal period for up to 2 years (Mandeville et al., 

1997). Thus, long-term rodent studies have failed to 

provide support for an association between magnetic 

field exposure and increased incidences of brain 

cancer. 

Several studies have suggested an association between the incidence of breast cancer and occupational 

exposure to magnetic fields (Matanoski et al., 1991; 

Stevens, 1993; Coogan et al., 1996). Alternating 

fields have also been reported to enhance the development of chemically induced mammary gland cancer 

in rats (Beniashvili et al., 1991; Mevissen et al., 

1993; Löscher et al., 1993, 1994; Löscher and 

Mevissen, 1994). Therefore, long-term rodent studies 

were examined for even minimal increases in breast 

cancer incidences. In the present study, no mammary 

gland carcinomas were diagnosed in mice. In male 

rats, one carcinoma was diagnosed in the 0.02 G 

group. In female rats, two carcinomas were found 

in the controls, seven in the 0.02 G group, five in 

the 2 G group, and two each in the 10 G intermittent 

and continuous exposure groups. The incidence in the 

0.02 G group was not statistically significant. In the 

study by Mandeville et al. (1997), three carcinomas of 

the mammary gland were found in the 0.02 G group 

compared to two carcinomas in the controls, which 

provides no support for a low field intensity effect. 

As in the present study, there was no increase in the 

incidences of mammary gland carcinoma at the higher 

exposure intensities. In a companion series of studies, 

no effect of magnetic fields on chemically induced 

breast cancer was observed in female Sprague-Dawley 

rats (NTP, 1999). 

Electric or magnetic field exposures have been 

hypothesized to depress nocturnal melatonin concentrations in rodents (Wilson et al., 1986, 1989; 

Lerchl et al., 1991; Reiter, 1992; Stevens et al., 

1992; Anderson, 1993; Stevens, 1993), possibly 

leading to increased rates of breast cancer. However, 

more recent studies cast some doubt on the effect of 

alternating magnetic field exposures on nocturnal 

melatonin levels (Truong et al., 1996; Yellon, 1996). 

Melatonin suppression is an attractive hypothesis 

because melatonin is reported to be oncostatic (Reiter, 

1992, 1993; Stevens et al., 1992; Liburdy et al., 

1993). In one study in rats, serum melatonin concentrations, but not pineal gland melatonin synthesis, 

were reduced; this suggests the possibility that 

degradation or tissue uptake of melatonin is stimulated 

by exposure to electric fields (Grota et al., 1994). 

Other studies have reported that serotonin-Nacetyltransferase, the rate-limiting enzyme for melatonin production, may be depressed by magnetic field 

exposure (Olcese and Reuss, 1986). In the 8-week 

NTP studies with 60-Hz magnetic field exposures at 

up to 10 G, no alterations in serum or pineal gland 

melatonin or pineal serotonin-N-acetyltransferase were 

found (NTP, 1996). That study had the limitation that 

only one nocturnal time point was evaluated; thus, the 

magnitude of the pineal gland response but not the 

duration of the melatonin secretion could be evaluated. Further, the NTP studies used linearly polarized 

magnetic fields, and it has been suggested that linearly 

polarized or vertical fields do not affect melatonin 

concentrations while circularly polarized fields will 

depress melatonin concentrations in rats (Kato et al., 

1994a,b). 

The increase in incidences of thyroid gland C-cell 

adenoma and carcinoma (combined) in male rats was 

considered an equivocal finding for several reasons. 

First, the increase in thyroid gland C-cell neoplasm 

incidence was not related to field intensity. The highest incidence was observed at 0.02 G, and there was 

no significant increase in thyroid gland C-cell neoplasm incidence at 10 G. 

Second, there is no supporting evidence from preneoplastic lesions. Generally, agents that cause neoplasia 

also increase incidences of preneoplastic lesions (in 

this case thyroid gland C-cell hyperplasia), but the 

highest incidence of thyroid gland C-cell hyperplasia 

was observed in the controls. C-cell adenomas do 

not differ morphologically from hyperplasia except 

for size (Boorman et al., 1972, 1974), and the 

combined incidences of adenoma or hyperplasia did 

not differ between groups. On the other hand, more 

thyroid gland C-cell adenomas were bilateral in the 

exposed animals than in the controls. It is unlikely 

that any variability between groups resulted from 

diagnostic differences. C-cell lesions represent a 

spectrum from small focal increases in C-cells to 

clusters of cells that fill thyroid follicles and eventually spread outside of the thyroid gland. Small focal 

lesions are diagnosed as C-cell hyperplasia, larger 

lesions as C-cell adenoma, and invasive lesions as 

C-cell carcinoma (Hardisty and Boorman, 1990). 
50 60-Hz Magnetic Fields, NTP TR 488 

Thus, moderate differences in diagnostic criteria can 

lead to different incidences in various studies and 

exposure groups. To control for possible diagnostic 

differences in this study, the reviewing pathologist 

evaluated all thyroid glands for the presence of 

proliferative lesions, and a Pathology Working Group 

resolved diagnostic differences between the study 

pathologists. This procedure helps reduce diagnostic 

inconsistencies, and the NTP believes that diagnostic 

differences can be ruled out as a possible source of 

variability between groups. 

Third, thyroid gland C-cell neoplasm incidences tend 

to be variable in NTP studies. In 18 recent NTP feed 

studies, the incidences of combined C-cell adenoma or 

carcinoma varied from 4% to 24%. Similarly, in 

18 recent inhalation studies, the incidences of combined C-cell adenoma or carcinoma varied from 4% 

to 19%. The thyroid gland C-cell neoplasm incidences in this study cannot be directly compared to 

historical control incidences because rats in the 

present study were fed the NTP-2000 diet whereas 

historical studies used the NIH-07 diet. Further, two 

sections were taken of each thyroid gland in this 

study, whereas in previous studies, usually one 

section was taken. Thompson and Hunt (1963) 

determined that the numbers of microscopic C-cell 

adenomas detected are subject to sampling technique, 

with an 8% incidence found with single sections of the 

thyroid gland compared to a 33% incidence with serial 

sections. 

Fourth, the thyroid gland C-cell is an infrequent 

site for a carcinogenic response. In an evaluation 

of 194 NTP 2-year studies in male F344/N rats, 

Haseman and Elwell (1996) found only one chemical 

(Ziram) that produced an increased incidence of thyroid gland C-cell neoplasms judged to be chemically 

related (4/50, 9/49, and 12/49 for control, low-dose, 

and high-dose groups, respectively). Conversely, it 

may be argued that an increased neoplasm incidence 

at a site that is rarely increased by chemical exposure 

is more important. 

Fifth, 60-Hz magnetic fields were not expected to increase thyroid gland C-cell cancer incidences. None 

of the epidemiology studies to date suggest an association between thyroid gland C-cell neoplasms and 

magnetic field exposure (Savitz, 1993; Theriault 

et al., 1994). As detailed above, mononuclear cell 

leukemia, mammary gland cancer, and brain cancer 

were considered the most likely neoplasms to arise in 

the present study, but no increases in the incidences of 

these neoplasms were found. Magnetic fields are 

reported to alter calcium flux in thymocytes in vitro 

(Walleczek and Liburdy, 1990), and C-cells are 

sensitive to and respond to changes in calcium 

concentrations (Black et al., 1973; Boorman et al., 

1974). However, there are no reports that subtle 

changes in intracellular calcium alter cancer rates in 

animals. 

Sixth, there is no other support for a carcinogenic 

effect on thyroid gland C-cells in these studies or in 

other studies. In many cases of a chemically induced 

effect in rodents, increased incidences of cancers are 

seen in both genders and in other species. The 

combined incidences of thyroid gland C-cell adenoma 

or carcinoma were similar in all groups of female rats 

in this study, as were the incidences of C-cell hyperplasia. Thyroid gland C-cell neoplasms were not 

diagnosed in exposed mice in these studies. Thus, 

other gender and species combinations do not provide 

any support for the increased incidences of thyroid 

gland C-cell neoplasms found in male rats. This lack 

of an effect in other gender and species combinations, 

however, cannot be used to argue that the effect 

in males may not be a carcinogenic response. The 

studies of Mandeville et al. (1997) and of Yasui et al. 

(1997) in F344 rats reported no increases in the incidences of thyroid gland C-cell neoplasms in groups 

exposed to similar or higher magnetic field intensities. 

Finally, these studies involved approximately 40 tissue 

sites, four gender-species groups, four EMF exposure 

regimens, and 100 animals per group. Under these 

conditions, statistically significant differences in 

neoplasm incidence may arise by chance. Thyroid 

gland C-cell in male rats was the only tissue site 

showing a significant (P<0.01) EMF-related increase 

in neoplasm incidence, and this increase was seen in 

both the 0.02 and 2 G groups. The likelihood of 

finding at least one statistically significant (P<0.01) 

pairwise increase in neoplasm incidence arising by 

chance in the present studies is estimated to be 

approximately 50%. The corresponding likelihood of 

observing two or more exposure groups with a 

significantly (P<0.01) increased neoplasm incidence 

at the same site is approximately 9% to 10%. These 

calculations suggest that random variability cannot be 

ruled out as the source of the apparent increased 
__________ 

60-Hz Magnetic Fields, NTP TR 488 51 

incidences of thyroid gland C-cell neoplasms observed 

in these studies. 

For these reasons, NTP considers the evidence that 

the increased incidences of thyroid gland C-cell neoplasms in male rats are related to magnetic field exposure to be equivocal. 

CONCLUSIONS 

Under the conditions of these 2-year whole-body 

exposure studies, there was equivocal evidence of carcinogenic activity* of 60-Hz magnetic fields in male 

F344/N rats based on increased incidences of thyroid 

gland C-cell neoplasms in the 0.02 and 2 G groups. 

There was no evidence of carcinogenic activity in 

female F344/N rats or male or female B6C3F1 mice 

exposed to 0.02, 2, or 10 G, or 10 G intermittent 

60-Hz magnetic fields. 

In exposed rats and mice, there were no increased 

incidences of neoplasms at sites for which epidemiology studies have suggested an association with 

magnetic fields (brain, mammary gland, leukemia). 

* Explanation of Levels of Evidence of Carcinogenic Activity is on page 8. A summary of the Technical Reports Review Subcommittee 

comments and the public discussion on this Technical Report appears on page 10. 
52 60-Hz Magnetic Fields, NTP TR 488 

 

53 

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62 60-Hz Magnetic Fields, NTP TR 488 

 


 


 


 

63 

APPENDIX A
 

SUMMARY OF LESIONS IN MALE RATS
 

IN THE 2-YEAR WHOLE-BODY EXPOSURE STUDY
 

OF 60-HZ MAGNETIC FIELDS
 

TABLE A1 Summary of the Incidence of Neoplasms in Male Rats 

in the 2-Year Whole-Body Exposure Study of 60-Hz Magnetic Fields .............. 64 

TABLE A2 Statistical Analysis of Primary Neoplasms in Male Rats 

in the 2-Year Whole-Body Exposure Study of 60-Hz Magnetic Fields .............. 69 

TABLE A3 Summary of the Incidence of Nonneoplastic Lesions in Male Rats 

in the 2-Year Whole-Body Exposure Study of 60-Hz Magnetic Fields .............. 74 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

64 60-Hz Magnetic Fields, NTP TR 488 

TABLE A1 

Summary of the Incidence of Neoplasms in Male Rats in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fieldsa 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Disposition Summary 

Animals initially in study 100 100 100 100 100 

Early deaths 

Moribund 29 32 32 36 33 

Natural deaths 14 21 21 16 7 

Other 1 1 

Survivors 

Terminal sacrifice 57 46 47 48 59 

Animals examined microscopically 100 100 100 100 100 

Alimentary System 

Intestine large, colon (100) (99) (99) (100) (99) 

Intestine large, rectum (99) (100) (100) (99) (100) 

Polyp adenomatous 1 (1%) 

Intestine large, cecum (98) (99) (97) (100) (99) 

Sarcoma 1 (1%) 

Intestine small, duodenum (99) (94) (100) (100) (98) 

Intestine small, jejunum (91) (90) (95) (98) (98) 

Intestine small, ileum (94) (92) (97) (96) (97) 

Sarcoma 1 (1%) 

Liver (100) (100) (100) (100) (100) 

Hepatocellular adenoma 1 (1%) 1 (1%) 2 (2%) 2 (2%) 

Hepatocellular adenoma, multiple 1 (1%) 1 (1%) 

Leiomyosarcoma, metastatic, spleen 1 (1%) 

Osteosarcoma, metastatic, bone 1 (1%) 

Mesentery (17) (22) (27) (21) (16) 

Leiomyosarcoma, metastatic, spleen 1 (5%) 

Lipoma 1 (5%) 

Osteosarcoma, metastatic, kidney 1 (4%) 

Oral mucosa (1) 

Squamous cell carcinoma 1 (100%) 

Pancreas (98) (99) (99) (99) (100) 

Mixed tumor benign 1 (1%) 

Acinus, adenoma 3 (3%) 5 (5%) 6 (6%) 5 (5%) 2 (2%) 

Salivary glands (99) (99) (100) (100) (100) 

Schwannoma malignant, metastatic, skin 1 (1%) 

Stomach, forestomach (100) (100) (100) (100) (100) 

Squamous cell papilloma 1 (1%) 

Stomach, glandular (100) (100) (100) (100) (100) 

Leiomyosarcoma, metastatic, spleen 1 (1%) 

Tooth (2) (1) (1) (1) (6) 

Odontoma 1 (100%) 

Cardiovascular System 

Heart (100) (100) (100) (100) (100) 

Osteosarcoma, metastatic, bone 1 (1%) 

Schwannoma malignant 2 (2%) 1 (1%) 1 (1%) 1 (1%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

60-Hz Magnetic Fields, NTP TR 488 65 

TABLE A1 

Summary of the Incidence of Neoplasms in Male Rats in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Endocrine System 

Adrenal cortex (99) (100) (100) (100) (100) 

Adenoma 3 (3%) 1 (1%) 1 (1%) 1 (1%) 

Adrenal medulla (98) (93) (100) (100) (95) 

Pheochromocytoma malignant 2 (2%) 2 (2%) 2 (2%) 

Pheochromocytoma complex 1 (1%) 

Pheochromocytoma benign 19 (19%) 19 (20%) 15 (15%) 17 (17%) 25 (26%) 

Bilateral, pheochromocytoma benign 5 (5%) 3 (3%) 6 (6%) 6 (6%) 8 (8%) 

Islets, pancreatic (99) (99) (99) (99) (100) 

Adenoma 3 (3%) 2 (2%) 5 (5%) 3 (3%) 2 (2%) 

Adenoma, multiple 1 (1%) 1 (1%) 

Carcinoma 1 (1%) 2 (2%) 1 (1%) 3 (3%) 

Parathyroid gland (85) (87) (93) (81) (89) 

Adenoma 1 (1%) 2 (2%) 2 (2%) 

Carcinoma, metastatic, skin 1 (1%) 

Carcinoma, metastatic, thyroid gland 1 (1%) 

Pineal gland (81) (84) (81) (79) (91) 

Pituitary gland (98) (95) (97) (100) (98) 

Pars distalis, adenoma 34 (35%) 34 (36%) 28 (29%) 35 (35%) 40 (41%) 

Pars distalis, adenoma, multiple 1 (1%) 

Pars distalis, carcinoma 1 (1%) 2 (2%) 3 (3%) 

Pars intermedia, adenoma 1 (1%) 1 (1%) 1 (1%) 

Pars nervosa, schwannoma malignant 1 (1%) 

Thyroid gland (99) (100) (100) (100) (100) 

Bilateral, C-cell, adenoma 2 (2%) 4 (4%) 1 (1%) 3 (3%) 

Bilateral, C-cell, carcinoma 1 (1%) 

C-cell, adenoma 15 (15%) 23 (23%) 22 (22%) 22 (22%) 15 (15%) 

C-cell, carcinoma 1 (1%) 6 (6%) 4 (4%) 2 (2%) 5 (5%) 

Follicular cell, adenoma 1 (1%) 

General Body System 

Peritoneum (1) (1) (1) 

Tissue NOS (3) (2) (1) (2) 

Abdominal, carcinoma 1 (50%) 

Abdominal, sarcoma 1 (33%) 

Mediastinum, schwannoma malignant 1 (33%) 

Thoracic, squamous cell carcinoma,

 metastatic, lung 1 (100%) 

Genital System 

Epididymis (100) (100) (100) (100) (100) 

Fibrosarcoma 1 (1%) 

Preputial gland (100) (99) (100) (99) (100) 

Adenoma 10 (10%) 8 (8%) 10 (10%) 12 (12%) 9 (9%) 

Carcinoma 5 (5%) 2 (2%) 

Fibroma 1 (1%) 

Bilateral, adenoma 3 (3%) 1 (1%) 1 (1%) 1 (1%) 

Prostate (100) (99) (100) (99) (100) 

Adenoma 1 (1%) 

Leiomyosarcoma, metastatic, spleen 1 (1%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

66 60-Hz Magnetic Fields, NTP TR 488 

TABLE A1 

Summary of the Incidence of Neoplasms in Male Rats in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Genital System (continued) 

Seminal vesicle (100) (99) (100) (99) (100) 

Adenoma 2 (2%) 1 (1%) 

Leiomyosarcoma, metastatic, spleen 1 (1%) 

Testes (100) (100) (100) (100) (100) 

Bilateral, interstitial cell, adenoma 82 (82%) 73 (73%) 72 (72%) 71 (71%) 67 (67%) 

Interstitial cell, adenoma 11 (11%) 17 (17%) 19 (19%) 20 (20%) 22 (22%) 

Interstitial cell, carcinoma 1 (1%) 

Hematopoietic System 

Bone marrow (100) (100) (100) (99) (100) 

Lymph node (15) (7) (7) (13) (8) 

Lymph node, mandibular (99) (99) (100) (100) (100) 

Schwannoma malignant, metastatic, skin 1 (1%) 

Lymph node, mesenteric (100) (99) (100) (100) (100) 

Spleen (100) (100) (100) (100) (100) 

Fibroma 1 (1%) 1 (1%) 

Hemangiosarcoma 1 (1%) 1 (1%) 

Leiomyosarcoma, metastatic, spleen 1 (1%) 

Sarcoma 1 (1%) 

Thymus (97) (94) (95) (90) (95) 

Thymoma benign 2 (2%) 1 (1%) 1 (1%) 

Thymoma malignant 2 (2%) 

Integumentary System 

Mammary gland (99) (97) (100) (98) (95) 

Carcinoma 1 (1%) 

Fibroadenoma 6 (6%) 5 (5%) 11 (11%) 8 (8%) 8 (8%) 

Fibroadenoma, multiple 1 (1%) 1 (1%)

 Skin (99) (100) (100) (100) (100) 

Basal cell adenoma 3 (3%) 3 (3%) 3 (3%) 2 (2%) 

Keratoacanthoma 10 (10%) 4 (4%) 11 (11%) 10 (10%) 8 (8%) 

Keratoacanthoma, multiple 1 (1%) 1 (1%) 

Melanoma malignant 1 (1%) 

Squamous cell carcinoma 1 (1%) 

Squamous cell papilloma 1 (1%) 2 (2%) 1 (1%) 

Trichoepithelioma 1 (1%) 5 (5%) 

Dermis, fibroma 3 (3%) 2 (2%) 4 (4%) 5 (5%) 4 (4%) 

Dermis, fibroma, multiple 1 (1%) 

Lip, basal cell adenoma 1 (1%) 

Lip, squamous cell papilloma 1 (1%) 

Pinna, melanoma malignant 1 (1%) 1 (1%) 

Prepuce, keratoacanthoma 1 (1%) 1 (1%) 

Prepuce, squamous cell carcinoma 1 (1%) 

Sebaceous gland, adenoma 1 (1%) 2 (2%) 1 (1%) 1 (1%) 

Sebaceous gland, carcinoma 1 (1%) 

Subcutaneous tissue, fibroma 9 (9%) 6 (6%) 6 (6%) 10 (10%) 8 (8%) 

Subcutaneous tissue, fibrosarcoma 1 (1%) 1 (1%) 1 (1%) 1 (1%) 

Subcutaneous tissue, leiomyosarcoma,

 metastatic, spleen 1 (1%) 

Subcutaneous tissue, lipoma 1 (1%) 2 (2%) 1 (1%) 

Subcutaneous tissue, melanoma malignant 1 (1%) 

Subcutaneous tissue, sarcoma 1 (1%) 1 (1%) 3 (3%) 1 (1%) 

Subcutaneous tissue, schwannoma malignant 1 (1%) 1 (1%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

60-Hz Magnetic Fields, NTP TR 488 67 

TABLE A1 

Summary of the Incidence of Neoplasms in Male Rats in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Musculoskeletal System 

Bone (100) (100) (100) (100) (100) 

Osteosarcoma 1 (1%) 

Femur, osteosarcoma, metastatic, bone 1 (1%) 

Maxilla, osteosarcoma 1 (1%) 

Skeletal muscle (10) (6) (11) (4) (7) 

Sarcoma 1 (9%) 

Nervous System 

Brain (100) (100) (100) (100) (100) 

Cerebellum, schwannoma malignant, 

metastatic, skin 1 (1%) 

Cerebrum, astrocytoma malignant 1 (1%) 

Cerebrum, oligodendroglioma malignant 1 (1%) 1 (1%) 

Cranial nerve, schwannoma malignant 1 (1%) 

Spinal cord (11) (6) (9) (4) (6) 

Respiratory System 

Lung (100) (100) (100) (100) (100) 

Alveolar/bronchiolar adenoma 3 (3%) 5 (5%) 5 (5%) 4 (4%) 

Alveolar/bronchiolar carcinoma 2 (2%) 

Carcinoma 1 (1%) 

Carcinoma, metastatic, thyroid gland 1 (1%) 

Chordoma, metastatic, uncertain primary site 1 (1%) 

Leiomyosarcoma, metastatic, spleen 1 (1%) 

Melanoma malignant, metastatic, skin 1 (1%) 1 (1%) 

Osteosarcoma, metastatic, bone 1 (1%) 1 (1%) 

Osteosarcoma, metastatic, uncertain primary

 site 1 (1%) 

Pheochromocytoma malignant, metastatic,

 adrenal medulla 1 (1%) 

Bronchus, adenoma 1 (1%) 

Bronchus, squamous cell carcinoma 1 (1%) 

Nose (100) (98) (100) (100) (100) 

Squamous cell carcinoma 1 (1%) 

Trachea (100) (100) (100) (100) (100) 

Special Senses System 

Harderian gland (100) (100) (100) (100) (100) 

Adenoma 1 (1%) 1 (1%) 

Squamous cell carcinoma, metastatic, skin 1 (1%) 

Zymbal’s gland (1) (2) (1) (1) (1) 

Adenoma 1 (50%) 

Carcinoma 1 (100%) 1 (50%) 1 (100%) 1 (100%) 
 

 

 

 

 

 

 

 

68 

c 

60-Hz Magnetic Fields, NTP TR 488 

TABLE A1 

Summary of the Incidence of Neoplasms in Male Rats in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Urinary System 

Kidney (100) (100) (100) (100) (100) 

Fibroma 1 (1%) 

Leiomyosarcoma, metastatic, spleen 1 (1%) 

Nephroblastoma 1 (1%) 

Osteosarcoma, metastatic, bone 1 (1%) 

Sarcoma 1 (1%) 

Capsule, sarcoma 1 (1%) 

Pelvis, transitional epithelium, carcinoma 1 (1%) 

Renal tubule, adenoma 1 (1%) 

Renal tubule, carcinoma 1 (1%) 

Urinary bladder (99) (96) (100) (100) (99) 

Transitional epithelium, papilloma 1 (1%) 1 (1%) 

Systemic Lesions 

Multiple organsb (100) (100) (100) (100) (100) 

Leukemia mononuclear 50 (50%) 44 (44%) 47 (47%) 50 (50%) 36 (36%) 

Lymphoma malignant 1 (1%) 

Mesothelioma malignant 4 (4%) 6 (6%) 5 (5%) 6 (6%) 4 (4%) 

Neoplasm Summary 

Total animals with primary neoplasmsc 100 98 98 100 98 

Total primary neoplasms 298 304 317 327 303 

Total animals with benign neoplasms 99 97 97 98 94 

Total benign neoplasms 229 230 245 253 233 

Total animals with malignant neoplasms 65 59 61 65 58 

Total malignant neoplasms 69 74 72 74 70 

Total animals with metastatic neoplasms 1 5 2 4 2 

Total metastatic neoplasms 1 5 4 15 4 

Total animals with malignant neoplasms

 of uncertain primary site 1 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 

Primary neoplasms: all neoplasms except metastatic neoplasms 

 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 

60-Hz Magnetic Fields, NTP TR 488 69 

TABLE A2 

Statistical Analysis of Primary Neoplasms in Male Rats in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Adrenal Medulla: Benign Pheochromocytoma 

Overall ratea 24/98 (24%) 22/93 (24%) 21/100 (21%) 23/100 (23%) 33/95 (35%) 

Adjusted rateb 27.8% 28.3% 24.5% 27.8% 39.9% 

Terminal ratec 17/57 (30%) 9/43 (21%) 10/47 (21%) 14/48 (29%) 19/56 (34%) 

First incidence (days) 619 505 617 488 552 

Poly-3 testd P=0.529 P=0.538 P=0.379N P=0.567 P=0.063 

Adrenal Medulla: Benign, Complex, or Malignant Pheochromocytoma 

Overall rate 26/98 (27%) 23/93 (25%) 21/100 (21%) 23/100 (23%) 35/95 (37%)
 

Adjusted rate 30.1% 29.6% 24.5% 27.8% 42.2%
 

Terminal rate 19/57 (33%) 10/43 (23%) 10/47 (21%) 14/48 (29%) 20/56 (36%)
 

First incidence (days) 619 505 617 488 552
 

Poly-3 test P=0.457N P=0.542N P=0.258N P=0.436N P=0.066
 

Lung: Alveolar/bronchiolar Adenoma 

Overall rate 3/100 (3%) 5/100 (5%) 5/100 (5%) 4/100 (4%) 0/100 (0%) 

Adjusted rate 3.5% 6.1% 6.0% 4.9% 0.0% 

Terminal rate 3/57 (5%) 4/46 (9%) 5/47 (11%) 3/48 (6%) 0/59 (0%) e First incidence (days) 736 (T) 647 736 (T) 673 —
 

Poly-3 test P=0.593 P=0.333 P=0.345 P=0.471 P=0.127N
 

Lung: Alveolar/bronchiolar Adenoma or Carcinoma 

Overall rate 3/100 (3%) 7/100 (7%) 5/100 (5%) 5/100 (5%) 0/100 (0%)
 

Adjusted rate 3.5% 8.6% 6.0% 6.2% 0.0%
 

Terminal rate 3/57 (5%) 6/46 (13%) 5/47 (11%) 4/48 (8%) 0/59 (0%)
 

First incidence (days) 736 (T) 647 736 (T) 673 —
 

Poly-3 test P=0.558 P=0.145 P=0.345 P=0.330 P=0.127N
 

Mammary Gland: Fibroadenoma 

Overall rate 6/100 (6%) 6/100 (6%) 11/100 (11%) 9/100 (9%) 8/100 (8%)
 

Adjusted rate 7.0% 7.4% 13.1% 11.0% 9.5%
 

Terminal rate 6/57 (11%) 4/46 (9%) 6/47 (13%) 6/48 (13%) 5/59 (9%)
 

First incidence (days) 736 (T) 712 672 673 600
 

Poly-3 test P=0.269 P=0.583 P=0.142 P=0.259 P=0.380
 

Mammary Gland: Fibroadenoma or Carcinoma 

Overall rate 6/100 (6%) 7/100 (7%) 11/100 (11%) 9/100 (9%) 8/100 (8%)
 

Adjusted rate 7.0% 8.6% 13.1% 11.0% 9.5%
 

Terminal rate 6/57 (11%) 5/46 (11%) 6/47 (13%) 6/48 (13%) 5/59 (9%)
 

First incidence (days) 736 (T) 712 672 673 600
 

Poly-3 test P=0.316 P=0.462 P=0.142 P=0.259 P=0.380
 

Pancreas: Adenoma 

Overall rate 3/98 (3%) 5/99 (5%) 6/99 (6%) 5/99 (5%) 2/100 (2%)
 

Adjusted rate 3.5% 6.1% 7.2% 6.2% 2.4%
 

Terminal rate 2/57 (4%) 4/46 (9%) 5/47 (11%) 2/48 (4%) 1/59 (2%)
 

First incidence (days) 658 329 729 565 621
 

Poly-3 test P=0.449 P=0.335 P=0.238 P=0.332 P=0.505N
 
70 60-Hz Magnetic Fields, NTP TR 488 

TABLE A2 

Statistical Analysis of Primary Neoplasms in Male Rats in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Pancreatic Islets: Adenoma 

Overall rate 3/99 (3%) 3/99 (3%) 6/99 (6%) 3/99 (3%) 2/100 (2%) 

Adjusted rate 3.5% 3.7% 7.2% 3.7% 2.4% 

Terminal rate 2/57 (4%) 2/46 (4%) 6/47 (13%) 3/48 (6%) 0/59 (0%) 

First incidence (days) 714 659 736 (T) 736 (T) 675 

Poly-3 test P=0.551N P=0.636 P=0.237 P=0.633 P=0.506N 

Pancreatic Islets: Adenoma or Carcinoma 

Overall rate 4/99 (4%) 5/99 (5%) 6/99 (6%) 4/99 (4%) 5/100 (5%) 

Adjusted rate 4.7% 6.2% 7.2% 5.0% 5.9% 

Terminal rate 3/57 (5%) 2/46 (4%) 6/47 (13%) 3/48 (6%) 2/59 (3%) 

First incidence (days) 714 659 736 (T) 702 675 

Poly-3 test P=0.505N P=0.467 P=0.360 P=0.609 P=0.494 

Pituitary Gland (Pars Distalis): Adenoma 

Overall rate 34/98 (35%) 35/95 (37%) 28/97 (29%) 35/100 (35%) 40/98 (41%) 

Adjusted rate 38.8% 42.9% 33.5% 40.4% 46.0% 

Terminal rate 23/57 (40%) 20/45 (44%) 18/46 (39%) 16/48 (33%) 28/58 (48%) 

First incidence (days) 579 533 489 442 470 

Poly-3 test P=0.500 P=0.349 P=0.281N P=0.479 P=0.206 

Pituitary Gland (Pars Distalis): Adenoma or Carcinoma 

Overall rate 34/98 (35%) 36/95 (38%) 30/97 (31%) 35/100 (35%) 43/98 (44%) 

Adjusted rate 38.8% 44.0% 35.8% 40.4% 49.2% 

Terminal rate 23/57 (40%) 20/45 (44%) 19/46 (41%) 16/48 (33%) 29/58 (50%) 

First incidence (days) 579 533 489 442 470 

Poly-3 test P=0.534N P=0.295 P=0.401N P=0.479 P=0.103 

Preputial Gland: Adenoma 

Overall rate 13/100 (13%) 9/99 (9%) 10/100 (10%) 13/99 (13%) 10/100 (10%) 

Adjusted rate 15.0% 10.8% 11.6% 15.8% 11.8% 

Terminal rate 7/57 (12%) 4/45 (9%) 2/47 (4%) 7/47 (15%) 7/59 (12%) 

First incidence (days) 649 396 489 445 586 

Poly-3 test P=0.301 P=0.281N P=0.335N P=0.527 P=0.348N 

Preputial Gland: Carcinoma 

Overall rate 0/100 (0%) 0/99 (0%) 5/100 (5%) 0/99 (0%) 2/100 (2%) 

Adjusted rate 0.0% 0.0% 5.9% 0.0% 2.4% 

Terminal rate 0/57 (0%) 0/45 (0%) 2/47 (4%) 0/47 (0%) 0/59 (0%) 

First incidence (days) — 

Poly-3 test P=0.475N 

— 

—f 

477 

P=0.032 

— 

— 

558 

P=0.237 

Preputial Gland: Adenoma or Carcinoma 

Overall rate 13/100 (13%) 9/99 (9%) 13/100 (13%) 13/99 (13%) 12/100 (12%) 

Adjusted rate 15.0% 10.8% 15.0% 15.8% 14.0% 

Terminal rate 7/57 (12%) 4/45 (9%) 4/47 (9%) 7/47 (15%) 7/59 (12%) 

First incidence (days) 649 396 477 445 558 

Poly-3 test P=0.343 P=0.281N P=0.584N P=0.527 P=0.510N 

 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 

60-Hz Magnetic Fields, NTP TR 488 71 

TABLE A2 

Statistical Analysis of Primary Neoplasms in Male Rats in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Skin: Keratoacanthoma 

Overall rate 10/100 (10%) 5/100 (5%) 11/100 (11%) 12/100 (12%) 8/100 (8%)
 

Adjusted rate 11.6% 6.1% 13.0% 14.8% 9.5%
 

Terminal rate 7/57 (12%) 3/46 (7%) 6/47 (13%) 8/48 (17%) 6/59 (10%)
 

First incidence (days) 627 713 535 702 557
 

Poly-3 test P=0.139 P=0.167N P=0.481 P=0.351 P=0.423N
 

Skin: Squamous Cell Papilloma or Keratoacanthoma 

Overall rate 11/100 (11%) 7/100 (7%) 12/100 (12%) 13/100 (13%) 8/100 (8%)
 

Adjusted rate 12.7% 8.6% 14.2% 16.0% 9.5%
 

Terminal rate 8/57 (14%) 3/46 (7%) 7/47 (15%) 9/48 (19%) 6/59 (10%)
 

First incidence (days) 627 688 535 702 557
 

Poly-3 test P=0.177 P=0.266N P=0.480 P=0.351 P=0.333N
 

Skin: Trichoepithelioma 

Overall rate 0/100 (0%) 1/100 (1%) 0/100 (0%) 5/100 (5%) 0/100 (0%)
 

Adjusted rate 0.0% 1.2% 0.0% 6.2% 0.0%
 

Terminal rate 0/57 (0%) 1/46 (2%) 0/47 (0%) 4/48 (8%) 0/59 (0%)
 

First incidence (days) — 736 (T) — 703 —
 

Poly-3 test P=0.002 P=0.490 — P=0.029 —
 

Skin: Trichoepithelioma or Basal Cell Adenoma 

Overall rate 3/100 (3%) 1/100 (1%) 3/100 (3%) 8/100 (8%) 3/100 (3%)
 

Adjusted rate 3.5% 1.2% 3.6% 9.8% 3.6%
 

Terminal rate 2/57 (4%) 1/46 (2%) 2/47 (4%) 5/48 (10%) 2/59 (3%)
 

First incidence (days) 659 736 (T) 586 656 582
 

Poly-3 test P=0.008 P=0.327N P=0.650 P=0.089 P=0.653
 

Skin: Squamous Cell Papilloma, Keratoacanthoma, or Squamous Cell Carcinoma 

Overall rate 11/100 (11%) 7/100 (7%) 12/100 (12%) 13/100 (13%) 10/100 (10%)
 

Adjusted rate 12.7% 8.6% 14.2% 16.0% 11.7%
 

Terminal rate 8/57 (14%) 3/46 (7%) 7/47 (15%) 9/48 (19%) 7/59 (12%)
 

First incidence (days) 627 688 535 702 470
 

Poly-3 test P=0.177 P=0.266N P=0.480 P=0.351 P=0.514N
 

Skin: Squamous Cell Papilloma, Keratoacanthoma, Trichoepithelioma, Basal Cell Adenoma, or Squamous Cell Carcinoma 

Overall rate 14/100 (14%) 8/100 (8%) 14/100 (14%) 20/100 (20%) 12/100 (12%)
 

Adjusted rate 16.1% 9.8% 16.4% 24.5% 14.0%
 

Terminal rate 10/57 (18%) 4/46 (9%) 8/47 (17%) 14/48 (29%) 8/59 (14%)
 

First incidence (days) 627 688 535 656 470
 

Poly-3 test P=0.018 P=0.159N P=0.563 P=0.122 P=0.428N
 

Skin (Dermis or Subcutaneous Tissue): Fibroma 

Overall rate 12/100 (12%) 8/100 (8%) 9/100 (9%) 13/100 (13%) 12/100 (12%)
 

Adjusted rate 13.9% 9.8% 10.6% 15.9% 14.2%
 

Terminal rate 9/57 (16%) 4/46 (9%) 4/47 (9%) 9/48 (19%) 8/59 (14%)
 

First incidence (days) 617 619 635 614 586
 

Poly-3 test P=0.211 P=0.278N P=0.339N P=0.438 P=0.568
 

 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 

72 60-Hz Magnetic Fields, NTP TR 488 

TABLE A2 

Statistical Analysis of Primary Neoplasms in Male Rats in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Skin (Dermis or Subcutaneous Tissue): Fibroma, Fibrosarcoma, or Sarcoma 

Overall rate 13/100 (13%) 10/100 (10%) 11/100 (11%) 16/100 (16%) 14/100 (14%)
 

Adjusted rate 15.0% 12.1% 13.0% 19.2% 16.5%
 

Terminal rate 9/57 (16%) 5/46 (11%) 6/47 (13%) 9/48 (19%) 10/59 (17%)
 

First incidence (days) 617 619 635 442 586
 

Poly-3 test P=0.141 P=0.374N P=0.435N P=0.303 P=0.477
 

Testes: Adenoma 

Overall rate 93/100 (93%) 90/100 (90%) 91/100 (91%) 91/100 (91%) 89/100 (89%)
 

Adjusted rate 95.1% 94.8% 94.4% 95.8% 93.8%
 

Terminal rate 54/57 (95%) 45/46 (98%) 43/47 (92%) 47/48 (98%) 57/59 (97%)
 

First incidence (days) 476 461 463 410 489
 

Poly-3 test P=0.450 P=0.600N P=0.544N P=0.556 P=0.460N
 

Thyroid Gland (C-cell): Adenoma 

Overall rate 15/99 (15%) 25/100 (25%) 26/100 (26%) 23/100 (23%) 18/100 (18%)
 

Adjusted rate 17.2% 30.0% 30.5% 27.4% 21.5%
 

Terminal rate 7/57 (12%) 15/46 (33%) 16/47 (34%) 13/48 (27%) 16/59 (27%)
 

First incidence (days) 583 589 604 561 725
 

Poly-3 test P=0.326 P=0.035 P=0.028 P=0.075 P=0.305
 

Thyroid Gland (C-cell): Carcinoma 

Overall rate 1/99 (1%) 7/100 (7%) 4/100 (4%) 2/100 (2%) 5/100 (5%)
 

Adjusted rate 1.2% 8.5% 4.8% 2.5% 5.9%
 

Terminal rate 1/57 (2%) 2/46 (4%) 2/47 (4%) 2/48 (4%) 4/59 (7%)
 

First incidence (days) 736 (T) 619 687 736 (T) 666
 

Poly-3 test P=0.280N P=0.030 P=0.177 P=0.483 P=0.103
 

Thyroid Gland (C-cell): Adenoma or Carcinoma 

Overall rate 16/99 (16%) 31/100 (31%) 30/100 (30%) 25/100 (25%) 22/100 (22%)
 

Adjusted rate 18.4% 36.8% 35.1% 29.8% 26.1%
 

Terminal rate 8/57 (14%) 17/46 (37%) 18/47 (38%) 15/48 (31%) 19/59 (32%)
 

First incidence (days) 583 589 604 561 666
 

Poly-3 test P=0.438 P=0.005 P=0.009 P=0.055 P=0.147
 

All Organs: Mononuclear Cell Leukemia 

Overall rate 50/100 (50%) 44/100 (44%) 47/100 (47%) 50/100 (50%) 36/100 (36%)
 

Adjusted rate 53.1% 50.0% 52.0% 56.2% 39.7%
 

Terminal rate 24/57 (42%) 18/46 (39%) 17/47 (36%) 22/48 (46%) 15/59 (25%)
 

First incidence (days) 303 533 479 410 527
 

Poly-3 test P=0.265 P=0.393N P=0.502N P=0.390 P=0.045N
 

All Organs: Malignant Mesothelioma 

Overall rate 4/100 (4%) 6/100 (6%) 5/100 (5%) 6/100 (6%) 4/100 (4%)
 

Adjusted rate 4.6% 7.2% 5.9% 7.2% 4.7%
 

Terminal rate 2/57 (4%) 1/46 (2%) 1/47 (2%) 2/48 (4%) 2/59 (3%)
 

First incidence (days) 658 581 568 488 576
 

Poly-3 test P=0.415 P=0.350 P=0.492 P=0.349 P=0.632
 
	 

c 

60-Hz Magnetic Fields, NTP TR 488 73 

TABLE A2 

Statistical Analysis of Primary Neoplasms in Male Rats in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

All Organs: Benign Neoplasms 

Overall rate 99/100 (99%) 97/100 (97%) 97/100 (97%) 98/100 (98%) 94/100 (94%) 

Adjusted rate 99.8% 99.4% 99.4% 99.5% 96.7% 

Terminal rate 57/57 (100%) 46/46 (100%) 47/47 (100%) 48/48 (100%) 58/59 (98%) 

First incidence (days) 303 329 463 410 470 

Poly-3 test P=0.876N P=0.906N P=0.926N P=0.941N P=0.092N 

All Organs: Malignant Neoplasms 

Overall rate 66/100 (66%) 59/100 (59%) 61/100 (61%) 66/100 (66%) 58/100 (58%) 

Adjusted rate 68.1% 64.7% 65.0% 69.4% 60.7% 

Terminal rate 32/57 (56%) 23/46 (50%) 23/47 (49%) 26/48 (54%) 26/59 (44%) 

First incidence (days) 303 466 477 410 365 

Poly-3 test P=0.325 P=0.365N P=0.380N P=0.483 P=0.173N 

All Organs: Benign or Malignant Neoplasms 

Overall rate 100/100 (100%) 98/100 (98%) 98/100 (98%) 100/100 (100%) 98/100 (98%) 

Adjusted rate 100.0% 99.7% 99.7% 100.0% 98.9% 

Terminal rate 57/57 (100%) 46/46 (100%) 47/47 (100%) 48/48 (100%) 58/59 (98%) 

First incidence (days) 303 329 463 410 365 

Poly-3 test P=0.957 P=0.985N P=0.999N — P=0.471N 

(T)Terminal sacrifice 

a Number of neoplasm-bearing animals/number of animals examined. Denominator is number of animals examined microscopically for adrenal gland, lung, 

pancreas, pancreatic islets, pituitary gland, preputial gland, testis, and thyroid gland; for other tissues, denominator is number of animals necropsied. b Poly-3 estimated neoplasm incidence after adjustment for intercurrent mortality 

Observed incidence at terminal kill 

d	 Beneath the control incidence are the P values associated with the trend test; the trend does not include the 10 G intermittent group. 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 negative trend or a lower incidence in an exposure group is indicated by N. e Not applicable; no neoplasms in animal group f Value of statistic cannot be computed. 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

74 60-Hz Magnetic Fields, NTP TR 488 

TABLE A3 

Summary of the Incidence of Nonneoplastic Lesions in Male Rats in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fieldsa 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Disposition Summary 

Animals initially in study 100 100 100 100 100 

Early deaths 

Moribund 29 32 32 36 33 

Natural deaths 14 21 21 16 7 

Other 1 1 

Survivors 

Terminal sacrifice 57 46 47 48 59 

Animals examined microscopically 100 100 100 100 100 

Alimentary System 

Intestine large, colon (100) (99) (99) (100) (99) 

Inflammation, chronic 1 (1%) 

Parasite metazoan 1 (1%) 

Intestine large, rectum (99) (100) (100) (99) (100) 

Edema 1 (1%) 

Ulcer 1 (1%) 

Intestine large, cecum (98) (99) (97) (100) (99) 

Edema 1 (1%) 1 (1%) 1 (1%) 

Inflammation, chronic active 1 (1%) 

Parasite metazoan 1 (1%) 

Intestine small, duodenum (99) (94) (100) (100) (98) 

Inflammation, acute 1 (1%) 

Intestine small, ileum (94) (92) (97) (96) (97) 

Inflammation, chronic 1 (1%) 1 (1%) 

Peyer’s patch, hyperplasia, lymphoid 2 (2%) 1 (1%) 

Liver (100) (100) (100) (100) (100) 

Angiectasis, focal 1 (1%) 3 (3%) 1 (1%) 

Atrophy 1 (1%) 

Atypia cellular, focal 1 (1%) 

Basophilic focus 35 (35%) 35 (35%) 47 (47%) 37 (37%) 36 (36%) 

Clear cell focus 44 (44%) 37 (37%) 38 (38%) 35 (35%) 41 (41%) 

Degeneration, cystic, focal 8 (8%) 2 (2%) 11 (11%) 13 (13%) 5 (5%) 

Eosinophilic focus 21 (21%) 19 (19%) 26 (26%) 17 (17%) 17 (17%) 

Hematopoietic cell proliferation 5 (5%) 4 (4%) 6 (6%) 3 (3%) 2 (2%) 

Hepatodiaphragmatic nodule 2 (2%) 5 (5%) 7 (7%) 1 (1%) 

Infiltration cellular, lymphocyte 1 (1%) 2 (2%) 

Infiltration cellular, mixed cell 11 (11%) 15 (15%) 9 (9%) 14 (14%) 26 (26%) 

Inflammation, chronic 2 (2%) 1 (1%) 1 (1%) 3 (3%) 

Inflammation, chronic active 1 (1%) 

Mixed cell focus 25 (25%) 28 (28%) 25 (25%) 23 (23%) 18 (18%) 

Necrosis 8 (8%) 6 (6%) 6 (6%) 4 (4%) 2 (2%) 

Pigmentation 1 (1%) 1 (1%) 2 (2%) 

Tension lipidosis 1 (1%) 

Artery, inflammation, chronic 1 (1%) 

Bile duct, hyperplasia 79 (79%) 88 (88%) 88 (88%) 74 (74%) 79 (79%) 

Centrilobular, necrosis 1 (1%) 

Hepatocyte, degeneration 1 (1%) 

Hepatocyte, hypertrophy 1 (1%) 

Hepatocyte, vacuolization cytoplasmic 14 (14%) 13 (13%) 19 (19%) 19 (19%) 20 (20%) 

Hepatocyte, vacuolization cytoplasmic, focal 1 (1%) 1 (1%) 

a Number of animals examined microscopically at the site and the number of animals with lesion 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

60-Hz Magnetic Fields, NTP TR 488 75 

TABLE A3 

Summary of the Incidence of Nonneoplastic Lesions in Male Rats in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Alimentary System (continued) 

Mesentery (17) (22) (27) (21) (16) 

Accessory spleen 2 (13%) 

Inflammation, chronic 1 (4%) 

Artery, hemorrhage 1 (5%) 

Artery, inflammation, chronic 1 (6%) 

Fat, necrosis 14 (82%) 15 (68%) 23 (85%) 15 (71%) 13 (81%) 

Pancreas (98) (99) (99) (99) (100) 

Cyst 3 (3%) 1 (1%) 1 (1%) 1 (1%) 

Fibrosis, focal 1 (1%) 

Hemorrhage 1 (1%) 

Infiltration cellular, lymphocyte 5 (5%) 14 (14%) 13 (13%) 9 (9%) 3 (3%) 

Acinus, atrophy, diffuse 3 (3%) 1 (1%) 1 (1%) 1 (1%) 

Acinus, atrophy, focal 33 (34%) 26 (26%) 40 (40%) 27 (27%) 41 (41%) 

Acinus, basophilic focus 1 (1%) 1 (1%) 1 (1%) 1 (1%) 

Acinus, hyperplasia, focal 20 (20%) 21 (21%) 23 (23%) 20 (20%) 18 (18%) 

Acinus, inflammation, chronic 1 (1%) 1 (1%) 

Artery, inflammation, chronic 1 (1%) 2 (2%) 2 (2%) 1 (1%) 

Salivary glands (99) (99) (100) (100) (100) 

Mineralization 1 (1%) 

Bilateral, pigmentation 1 (1%) 

Parotid gland, atrophy 2 (2%) 2 (2%) 

Parotid gland, fibrosis, focal 1 (1%) 

Parotid gland, hyperplasia, focal 1 (1%) 1 (1%) 

Parotid gland, inflammation, chronic 1 (1%) 

Parotid gland, vacuolization cytoplasmic,

 diffuse 1 (1%) 

Sublingual gland, atrophy 1 (1%) 1 (1%) 

Sublingual gland, infiltration cellular,

 lymphocyte 1 (1%) 

Sublingual gland, inflammation, chronic 1 (1%) 

Submandibular gland, atrophy 1 (1%) 

Stomach, forestomach (100) (100) (100) (100) (100) 

Edema 3 (3%) 3 (3%) 5 (5%) 3 (3%) 6 (6%) 

Erosion, focal 1 (1%) 1 (1%) 1 (1%) 

Inflammation, acute 1 (1%) 1 (1%) 1 (1%) 

Inflammation, chronic 1 (1%) 1 (1%) 3 (3%) 

Inflammation, chronic active 2 (2%) 1 (1%) 4 (4%) 4 (4%) 1 (1%) 

Ulcer 1 (1%) 2 (2%) 2 (2%) 3 (3%) 7 (7%) 

Epithelium, hyperplasia 6 (6%) 5 (5%) 9 (9%) 2 (2%) 7 (7%) 

Stomach, glandular (100) (100) (100) (100) (100) 

Atrophy 3 (3%) 

Edema 2 (2%) 1 (1%) 

Erosion, focal 9 (9%) 3 (3%) 9 (9%) 8 (8%) 11 (11%) 

Hyperplasia, focal 1 (1%) 1 (1%) 

Inflammation, acute 1 (1%) 1 (1%) 

Inflammation, chronic 1 (1%) 

Inflammation, chronic active 1 (1%) 1 (1%) 1 (1%) 

Mineralization 1 (1%) 1 (1%) 

Ulcer 1 (1%) 

Artery, inflammation, chronic 1 (1%) 1 (1%) 

Epithelium, cyst 1 (1%) 

Glands, cyst 4 (4%) 6 (6%) 1 (1%) 3 (3%) 2 (2%) 

Muscularis, mineralization 1 (1%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

76 60-Hz Magnetic Fields, NTP TR 488 

TABLE A3 

Summary of the Incidence of Nonneoplastic Lesions in Male Rats in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Alimentary System (continued) 

Tooth (2) (1) (1) (1) (6) 

Malformation 5 (83%) 

Gingiva, inflammation, chronic active 2 (100%) 1 (100%) 1 (17%) 

Gingiva, malformation 1 (50%) 

Peridontal tissue, inflammation, chronic

 active 1 (100%) 

Cardiovascular System 

Blood vessel (99) (99) (99) (100) (100) 

Aneurysm 1 (1%) 

Inflammation, chronic 1 (1%) 

Mineralization 1 (1%) 1 (1%) 

Heart (100) (100) (100) (100) (100) 

Cardiomyopathy 88 (88%) 87 (87%) 88 (88%) 87 (87%) 87 (87%) 

Metaplasia, focal, osseous 1 (1%) 

Pigmentation 2 (2%) 

Artery, inflammation, chronic 1 (1%) 

Artery, mineralization 1 (1%) 1 (1%) 

Atrium, mineralization 1 (1%) 

Atrium, thrombosis 6 (6%) 6 (6%) 6 (6%) 9 (9%) 4 (4%) 

Epicardium, inflammation, chronic 1 (1%) 

Myocardium, necrosis 1 (1%) 

Pericardium, inflammation, chronic 1 (1%) 

Valve, inflammation, chronic 1 (1%) 2 (2%) 

Endocrine System 

Adrenal cortex (99) (100) (100) (100) (100) 

Accessory adrenal cortical nodule 1 (1%) 2 (2%) 3 (3%) 

Angiectasis 4 (4%) 1 (1%) 

Degeneration, focal 1 (1%) 

Hematopoietic cell proliferation 1 (1%) 4 (4%) 3 (3%) 2 (2%) 6 (6%) 

Hemorrhage 1 (1%) 1 (1%) 

Hyperplasia, focal 11 (11%) 15 (15%) 9 (9%) 11 (11%) 9 (9%) 

Hypertrophy, focal 3 (3%) 3 (3%) 6 (6%) 3 (3%) 

Necrosis, focal 2 (2%) 

Pigmentation 1 (1%) 

Vacuolization cytoplasmic, focal 14 (14%) 19 (19%) 19 (19%) 20 (20%) 19 (19%) 

Bilateral, angiectasis 5 (5%) 8 (8%) 2 (2%) 2 (2%) 2 (2%) 

Bilateral, hematopoietic cell proliferation 2 (2%) 3 (3%) 2 (2%) 3 (3%) 

Bilateral, hyperplasia, focal 1 (1%) 

Bilateral, infiltration cellular, mixed cell 1 (1%) 

Bilateral, necrosis 1 (1%) 

Bilateral, pigmentation 1 (1%) 1 (1%) 1 (1%) 

Bilateral, vacuolization cytoplasmic, diffuse 1 (1%) 2 (2%) 4 (4%) 3 (3%) 

Bilateral, vacuolization cytoplasmic, focal 6 (6%) 5 (5%) 4 (4%) 5 (5%) 1 (1%) 

Adrenal medulla (98) (93) (100) (100) (95) 

Degeneration, cystic 1 (1%) 

Hyperplasia, focal 14 (14%) 11 (12%) 9 (9%) 16 (16%) 13 (14%) 

Infiltration cellular, lymphocyte 1 (1%) 1 (1%) 

Thrombosis 1 (1%) 

Bilateral, hyperplasia, focal 3 (3%) 5 (5%) 2 (2%) 2 (2%) 1 (1%) 

Bilateral, infiltration cellular, lymphocyte 1 (1%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

60-Hz Magnetic Fields, NTP TR 488 77 

TABLE A3 

Summary of the Incidence of Nonneoplastic Lesions in Male Rats in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Endocrine System (continued) 

Islets, pancreatic (99) (99) (99) (99) (100) 

Hyperplasia, focal 1 (1%) 1 (1%) 9 (9%) 2 (2%) 7 (7%) 

Inflammation, chronic, focal 1 (1%) 

Metaplasia, focal 1 (1%) 

Parathyroid gland (85) (87) (93) (81) (89) 

Hyperplasia, focal 1 (1%) 1 (1%) 1 (1%) 

Pineal gland (81) (84) (81) (79) (91) 

Fibrosis 1 (1%) 

Hyperplasia, focal 1 (1%) 

Infiltration cellular, lymphocyte 1 (1%) 1 (1%) 2 (2%) 

Mineralization 42 (52%) 52 (62%) 54 (67%) 39 (49%) 57 (63%) 

Pituitary gland (98) (95) (97) (100) (98) 

Inflammation, granulomatous 1 (1%) 

Pars distalis, angiectasis, focal 3 (3%) 2 (2%) 4 (4%) 2 (2%) 2 (2%) 

Pars distalis, atrophy, focal 1 (1%) 

Pars distalis, cyst 8 (8%) 6 (6%) 6 (6%) 16 (16%) 7 (7%) 

Pars distalis, hemorrhage 1 (1%) 

Pars distalis, hyperplasia, focal 11 (11%) 15 (16%) 9 (9%) 14 (14%) 16 (16%) 

Pars distalis, hypertrophy, focal 2 (2%) 2 (2%) 3 (3%) 2 (2%) 

Pars distalis, pigmentation, focal 1 (1%) 

Pars distalis, vacuolization cytoplasmic 2 (2%) 1 (1%) 1 (1%) 

Pars distalis, vacuolization cytoplasmic,

 focal 1 (1%) 

Pars intermedia, atypia cellular 1 (1%) 

Pars intermedia, cyst 3 (3%) 1 (1%) 2 (2%) 

Pars intermedia, hyperplasia, focal 1 (1%) 

Pars nervosa, atypia cellular 1 (1%) 

Pars nervosa, cyst 1 (1%) 

Pars nervosa, degeneration, focal 1 (1%) 

Rathke’s cleft, cyst 1 (1%) 1 (1%) 1 (1%) 

Thyroid gland (99) (100) (100) (100) (100) 

Hemorrhage 1 (1%) 

Inflammation, chronic 2 (2%) 2 (2%) 

Mineralization 1 (1%) 

Ultimobranchial cyst 1 (1%) 1 (1%) 4 (4%) 7 (7%) 3 (3%) 

Bilateral, C-cell, hyperplasia, focal 1 (1%) 1 (1%) 

C-cell, hyperplasia 1 (1%) 3 (3%) 1 (1%) 2 (2%) 

C-cell, hyperplasia, diffuse 4 (4%) 1 (1%) 

C-cell, hyperplasia, focal 28 (28%) 22 (22%) 23 (23%) 24 (24%) 31 (31%) 

Follicle, cyst 3 (3%) 2 (2%) 5 (5%) 2 (2%) 3 (3%) 

Follicular cell, hyperplasia, focal 1 (1%) 2 (2%) 1 (1%) 

General Body System 

Tissue NOS (3) (2) (1) (2) 

Necrosis 1 (33%) 

Genital System 

Epididymis (100) (100) (100) (100) (100) 

Atrophy 1 (1%) 

Granuloma sperm 2 (2%) 3 (3%) 

Infiltration cellular, lymphocyte 1 (1%) 1 (1%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

78 60-Hz Magnetic Fields, NTP TR 488 

TABLE A3 

Summary of the Incidence of Nonneoplastic Lesions in Male Rats in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Genital System (continued) 

Epididymis (continued) (100) (100) (100) (100) (100) 

Inflammation, acute 1 (1%) 

Inflammation, chronic 3 (3%) 4 (4%) 4 (4%) 5 (5%) 2 (2%) 

Inflammation, chronic active 1 (1%) 1 (1%) 1 (1%) 1 (1%) 

Inflammation, granulomatous 1 (1%) 

Artery, inflammation, chronic 1 (1%) 

Bilateral, inflammation, acute 1 (1%) 

Bilateral, inflammation, chronic 1 (1%) 

Bilateral, epithelium, degeneration, mucoid 58 (58%) 61 (61%) 54 (54%) 60 (60%) 54 (54%) 

Epithelium, degeneration, mucoid 24 (24%) 15 (15%) 29 (29%) 12 (12%) 25 (25%) 

Preputial gland (100) (99) (100) (99) (100) 

Cyst 1 (1%) 

Hyperplasia, focal 4 (4%) 8 (8%) 2 (2%) 4 (4%) 1 (1%) 

Inflammation, acute 1 (1%) 1 (1%) 

Inflammation, chronic 18 (18%) 19 (19%) 25 (25%) 31 (31%) 35 (35%) 

Inflammation, chronic active 4 (4%) 3 (3%) 2 (2%) 7 (7%) 4 (4%) 

Inflammation, granulomatous 1 (1%) 

Bilateral, atrophy 1 (1%) 1 (1%) 2 (2%) 

Bilateral, inflammation, chronic 47 (47%) 48 (48%) 44 (44%) 33 (33%) 34 (34%) 

Bilateral, inflammation, chronic active 11 (11%) 6 (6%) 5 (5%) 4 (4%) 11 (11%) 

Prostate (100) (99) (100) (99) (100) 

Atrophy 48 (48%) 57 (58%) 34 (34%) 47 (47%) 52 (52%) 

Cyst 1 (1%) 

Hypertrophy 1 (1%) 

Infiltration cellular, lymphocyte 2 (2%) 

Inflammation, acute 4 (4%) 7 (7%) 15 (15%) 7 (7%) 14 (14%) 

Inflammation, chronic 6 (6%) 6 (6%) 14 (14%) 6 (6%) 7 (7%) 

Inflammation, chronic active 36 (36%) 44 (44%) 36 (36%) 35 (35%) 39 (39%) 

Artery, inflammation, chronic 1 (1%) 

Bilateral, inflammation, chronic 1 (1%) 

Bilateral, inflammation, chronic active 1 (1%) 

Epithelium, hyperplasia, focal 10 (10%) 7 (7%) 5 (5%) 9 (9%) 12 (12%) 

Seminal vesicle (100) (99) (100) (99) (100) 

Atrophy 30 (30%) 48 (48%) 50 (50%) 38 (38%) 30 (30%) 

Dilatation 2 (2%) 

Inflammation, acute 1 (1%) 1 (1%) 

Inflammation, chronic active 1 (1%) 1 (1%) 

Bilateral, atrophy 54 (54%) 31 (31%) 36 (36%) 40 (40%) 49 (49%) 

Bilateral, dilatation 1 (1%) 2 (2%) 

Testes (100) (100) (100) (100) (100) 

Mineralization 1 (1%) 1 (1%) 4 (4%) 1 (1%) 

Necrosis 1 (1%) 

Bilateral, inflammation, chronic 1 (1%) 

Bilateral, mineralization 2 (2%) 

Bilateral, necrosis 1 (1%) 

Bilateral, artery, inflammation, chronic 1 (1%) 

Bilateral, interstitial cell, hyperplasia, diffuse 1 (1%) 

Bilateral, interstitial cell, hyperplasia, focal 3 (3%) 1 (1%) 5 (5%) 5 (5%) 3 (3%) 

Bilateral, germinal epithelium, atrophy 4 (4%) 3 (3%) 3 (3%) 2 (2%) 4 (4%) 

Germinal epithelium, atrophy 6 (6%) 11 (11%) 11 (11%) 10 (10%) 9 (9%) 

Germinal epithelium, hyperplasia, focal 1 (1%) 

Interstitial cell, hyperplasia, focal 8 (8%) 8 (8%) 12 (12%) 17 (17%) 21 (21%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

60-Hz Magnetic Fields, NTP TR 488 79 

TABLE A3 

Summary of the Incidence of Nonneoplastic Lesions in Male Rats in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Hematopoietic System 

Bone marrow (100) (100) (100) (99) (100) 

Depletion cellular 3 (3%) 2 (2%) 3 (3%) 2 (2%) 6 (6%) 

Hemorrhage 2 (2%) 1 (1%) 

Hyperplasia 14 (14%) 18 (18%) 15 (15%) 12 (12%) 12 (12%) 

Myelofibrosis 1 (1%) 

Necrosis 4 (4%) 

Lymph node (15) (7) (7) (13) (8) 

Hyperplasia, lymphoid 1 (7%) 1 (13%) 

Mediastinal, hemorrhage 2 (13%) 1 (14%) 1 (14%) 2 (15%) 1 (13%) 

Mediastinal, hyperplasia, lymphoid 1 (14%) 

Mediastinal, pigmentation 1 (7%) 1 (8%) 

Lymph node, mandibular (99) (99) (100) (100) (100) 

Atrophy 1 (1%) 

Degeneration, cystic 15 (15%) 10 (10%) 11 (11%) 12 (12%) 11 (11%) 

Fibrosis 1 (1%) 1 (1%) 

Hemorrhage 2 (2%) 1 (1%) 7 (7%) 1 (1%) 

Hyperplasia, lymphoid 17 (17%) 15 (15%) 14 (14%) 13 (13%) 14 (14%) 

Infiltration cellular, histiocyte 3 (3%) 4 (4%) 2 (2%) 

Pigmentation 1 (1%) 1 (1%) 1 (1%) 2 (2%) 

Lymph node, mesenteric (100) (99) (100) (100) (100) 

Angiectasis 1 (1%) 

Atrophy 1 (1%) 1 (1%) 

Degeneration, cystic 1 (1%) 2 (2%) 2 (2%) 1 (1%) 1 (1%) 

Hematopoietic cell proliferation 1 (1%) 

Hemorrhage 2 (2%) 2 (2%) 2 (2%) 2 (2%) 1 (1%) 

Hyperplasia, lymphoid 1 (1%) 1 (1%) 2 (2%) 3 (3%) 

Infiltration cellular, histiocyte 65 (65%) 70 (71%) 73 (73%) 70 (70%) 80 (80%) 

Inflammation, chronic 2 (2%) 

Pigmentation 1 (1%) 

Artery, inflammation, chronic active 1 (1%) 

Spleen (100) (100) (100) (100) (100) 

Accessory spleen 1 (1%) 1 (1%) 1 (1%) 

Congestion 3 (3%) 5 (5%) 1 (1%) 1 (1%) 

Depletion cellular, focal 1 (1%) 1 (1%) 

Fibrosis 1 (1%) 6 (6%) 4 (4%) 1 (1%) 1 (1%) 

Hematopoietic cell proliferation 14 (14%) 12 (12%) 13 (13%) 15 (15%) 16 (16%) 

Hemorrhage 1 (1%) 

Necrosis, focal 1 (1%) 

Pigmentation 12 (12%) 11 (11%) 17 (17%) 15 (15%) 19 (19%) 

Capsule, inflammation, chronic 3 (3%) 1 (1%) 

Capsule, pigmentation, focal 1 (1%) 

Lymphoid follicle, atrophy 1 (1%) 4 (4%) 3 (3%) 3 (3%) 3 (3%) 

Lymphoid follicle, hyperplasia 1 (1%) 

Thymus (97) (94) (95) (90) (95) 

Atrophy 58 (60%) 46 (49%) 63 (66%) 62 (69%) 44 (46%) 

Cyst 1 (1%) 2 (2%) 1 (1%) 2 (2%) 

Hemorrhage 2 (2%) 3 (3%) 2 (2%) 2 (2%) 

Hyperplasia, lymphoid 1 (1%) 1 (1%) 1 (1%) 

Epithelial cell, hyperplasia 2 (2%) 3 (3%) 3 (3%) 6 (7%) 2 (2%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

80 60-Hz Magnetic Fields, NTP TR 488 

TABLE A3 

Summary of the Incidence of Nonneoplastic Lesions in Male Rats in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Integumentary System 

Mammary gland (99) (97) (100) (98) (95) 

Cyst 18 (18%) 15 (15%) 10 (10%) 14 (14%) 14 (15%) 

Fibrosis 2 (2%) 1 (1%) 2 (2%) 

Galactocele 2 (2%) 5 (5%) 1 (1%) 5 (5%) 

Inflammation, chronic 1 (1%) 3 (3%) 1 (1%) 1 (1%) 

Inflammation, chronic active 1 (1%) 

Mineralization 2 (2%) 1 (1%) 1 (1%) 1 (1%) 

Pigmentation 2 (2%) 4 (4%) 

Epithelium, hyperplasia 9 (9%) 1 (1%) 4 (4%) 3 (3%) 4 (4%) 

Skin (99) (100) (100) (100) (100) 

Congestion 1 (1%) 

Cyst epithelial inclusion 4 (4%) 3 (3%) 3 (3%) 3 (3%) 

Hyperkeratosis 1 (1%) 

Inflammation, acute 1 (1%) 

Inflammation, chronic active 1 (1%) 

Dermis, fibrosis, focal 2 (2%) 1 (1%) 

Epidermis, hyperplasia 1 (1%) 

Hair follicle, hyperplasia, focal 1 (1%) 1 (1%) 

Lip, hemorrhage 1 (1%) 

Subcutaneous tissue, fibrosis 2 (2%) 1 (1%) 

Subcutaneous tissue, hemorrhage 1 (1%) 

Subcutaneous tissue, inflammation, chronic 1 (1%) 

Subcutaneous tissue, necrosis 1 (1%) 

Musculoskeletal System 

Bone (100) (100) (100) (100) (100) 

Cranium, hyperostosis 1 (1%) 1 (1%) 1 (1%) 1 (1%) 

Femur, hyperostosis 1 (1%) 2 (2%) 5 (5%) 2 (2%) 1 (1%) 

Femur, hypertrophy 1 (1%) 

Maxilla, osteomalacia 1 (1%) 

Turbinate, hyperostosis 1 (1%) 

Skeletal muscle (10) (6) (11) (4) (7) 

Infiltration cellular, lymphocyte 1 (17%) 

Inflammation, chronic, focal 1 (14%) 

Mineralization 1 (17%) 

Nervous System 

Brain (100) (100) (100) (100) (100) 

Artery, thrombosis 1 (1%) 

Cerebrum, hemorrhage 1 (1%) 

Cerebrum, hydrocephalus 1 (1%) 

Cerebrum, infiltration cellular, lymphocyte 1 (1%) 

Cerebrum, necrosis 2 (2%) 1 (1%) 

Choroid plexus, hyperplasia 1 (1%) 

Choroid plexus, mineralization 1 (1%) 1 (1%) 

Choroid plexus, cerebrum, infiltration

 cellular, lymphocyte 1 (1%) 

Hypothalamus, compression 5 (5%) 8 (8%) 1 (1%) 9 (9%) 8 (8%) 

Hypothalamus, necrosis, focal 1 (1%) 

Meninges, hyperplasia 1 (1%) 

Pons, compression 1 (1%) 

Thalamus, necrosis, focal 1 (1%) 

Spinal cord (11) (6) (9) (4) (6) 

Meninges, cyst epithelial inclusion 1 (9%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

60-Hz Magnetic Fields, NTP TR 488 81 

TABLE A3 

Summary of the Incidence of Nonneoplastic Lesions in Male Rats in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Respiratory System 

Lung (100) (100) (100) (100) (100) 

Congestion 5 (5%) 5 (5%) 2 (2%) 4 (4%) 3 (3%) 

Edema 1 (1%) 

Fibrosis, focal 1 (1%) 

Foreign body 1 (1%) 

Hemorrhage 1 (1%) 

Infiltration cellular, lymphocyte 11 (11%) 5 (5%) 2 (2%) 3 (3%) 

Infiltration cellular, histiocyte 8 (8%) 18 (18%) 12 (12%) 6 (6%) 5 (5%) 

Inflammation, acute 1 (1%) 

Inflammation, chronic, focal 1 (1%) 

Metaplasia, focal, osseous 1 (1%) 4 (4%) 1 (1%) 

Alveolar epithelium, hyperplasia, focal 6 (6%) 3 (3%) 7 (7%) 5 (5%) 4 (4%) 

Artery, inflammation, chronic 1 (1%) 

Bronchus, inflammation, acute 1 (1%) 1 (1%) 

Bronchus, inflammation, chronic 2 (2%) 

Bronchus, inflammation, chronic active 1 (1%) 

Interstitium, inflammation, acute 1 (1%) 

Interstitium, inflammation, chronic 5 (5%) 5 (5%) 3 (3%) 2 (2%) 3 (3%) 

Interstitium, inflammation, chronic active 1 (1%) 2 (2%) 

Serosa, inflammation, chronic 1 (1%) 

Nose (100) (98) (100) (100) (100) 

Congestion 1 (1%) 

Foreign body 1 (1%) 1 (1%) 1 (1%) 1 (1%) 

Inflammation, acute 1 (1%) 2 (2%) 

Inflammation, chronic 5 (5%) 3 (3%) 5 (5%) 4 (4%) 3 (3%) 

Inflammation, chronic active 22 (22%) 25 (26%) 35 (35%) 25 (25%) 31 (31%) 

Metaplasia, squamous 2 (2%) 

Mineralization, focal 1 (1%) 

Glands, cyst 1 (1%) 

Nasolacrimal duct, inflammation, acute 1 (1%) 1 (1%) 1 (1%) 

Nasolacrimal duct, inflammation, chronic 6 (6%) 8 (8%) 12 (12%) 7 (7%) 4 (4%) 

Nasolacrimal duct, inflammation, chronic

 active 1 (1%) 1 (1%) 3 (3%) 4 (4%) 

Olfactory epithelium, cyst 1 (1%) 

Olfactory epithelium, cytoplasmic alteration 36 (36%) 32 (33%) 48 (48%) 41 (41%) 29 (29%) 

Olfactory epithelium, mineralization 1 (1%) 

Respiratory epithelium, cyst 1 (1%) 1 (1%) 

Respiratory epithelium, cytoplasmic

 alteration 3 (3%) 1 (1%) 1 (1%) 1 (1%) 

Respiratory epithelium, hyperplasia, focal 1 (1%) 

Trachea (100) (100) (100) (100) (100) 

Inflammation, chronic 10 (10%) 12 (12%) 15 (15%) 3 (3%) 12 (12%) 

Inflammation, chronic active 1 (1%) 1 (1%) 

Glands, cyst 1 (1%) 1 (1%) 1 (1%) 

Special Senses System 

Eye (3) (2) (7) (1) 

Bilateral, lens, cataract 1 (14%) 

Bilateral, retina, atrophy 3 (43%) 

Iris, inflammation, chronic 1 (50%) 

Iris, synechia 1 (14%) 1 (100%) 

Lens, cataract 3 (100%) 1 (50%) 5 (71%) 1 (100%) 

Retina, atrophy 3 (100%) 2 (100%) 4 (57%) 1 (100%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

82 60-Hz Magnetic Fields, NTP TR 488 

TABLE A3 

Summary of the Incidence of Nonneoplastic Lesions in Male Rats in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Special Senses System (continued) 

Harderian gland (100) (100) (100) (100) (100) 

Atrophy, diffuse 1 (1%) 

Atrophy, focal 2 (2%) 1 (1%) 8 (8%) 2 (2%) 1 (1%) 

Hyperplasia, focal 2 (2%) 2 (2%) 4 (4%) 2 (2%) 

Infiltration cellular, lymphocyte 26 (26%) 30 (30%) 23 (23%) 25 (25%) 44 (44%) 

Inflammation, acute 1 (1%) 

Inflammation, chronic 3 (3%) 4 (4%) 6 (6%) 2 (2%) 1 (1%) 

Inflammation, chronic active 1 (1%) 

Pigmentation 1 (1%) 

Bilateral, atrophy, diffuse 1 (1%) 

Bilateral, atrophy, focal 1 (1%) 

Bilateral, infiltration cellular, lymphocyte 17 (17%) 19 (19%) 21 (21%) 21 (21%) 16 (16%) 

Bilateral, inflammation, chronic 5 (5%) 8 (8%) 5 (5%) 2 (2%) 5 (5%) 

Bilateral, inflammation, chronic active 1 (1%) 1 (1%) 

Bilateral, pigmentation 1 (1%) 

Urinary System 

Kidney (100) (100) (100) (100) (100) 

Cyst 1 (1%) 3 (3%) 1 (1%) 2 (2%) 1 (1%) 

Fibrosis, focal 2 (2%) 

Infarct 1 (1%) 1 (1%) 

Mineralization 16 (16%) 18 (18%) 14 (14%) 17 (17%) 16 (16%) 

Nephropathy 1 (1%) 1 (1%) 2 (2%) 1 (1%) 2 (2%) 

Artery, inflammation, chronic 1 (1%) 

Bilateral, hydronephrosis 1 (1%) 

Bilateral, mineralization 23 (23%) 10 (10%) 19 (19%) 14 (14%) 25 (25%) 

Bilateral, nephropathy 91 (91%) 84 (84%) 87 (87%) 85 (85%) 87 (87%) 

Bilateral, pigmentation 2 (2%) 1 (1%) 

Bilateral, artery, mineralization 1 (1%) 

Bilateral, papilla, necrosis 1 (1%) 1 (1%) 

Bilateral, pelvis, inflammation, acute 1 (1%) 

Bilateral, pelvis, inflammation, chronic 1 (1%) 

Bilateral, pelvis, inflammation, chronic

 active 1 (1%) 

Bilateral, renal tubule, crystals 1 (1%) 

Bilateral, renal tubule, degeneration 2 (2%) 2 (2%) 2 (2%) 1 (1%) 

Bilateral, renal tubule, pigmentation 29 (29%) 20 (20%) 26 (26%) 23 (23%) 35 (35%) 

Papilla, necrosis 1 (1%) 

Pelvis, inflammation, acute 1 (1%) 

Pelvis, inflammation, chronic 1 (1%) 

Pelvis, transitional epithelium, hyperplasia 2 (2%) 1 (1%) 

Renal tubule, hyperplasia, focal 1 (1%) 1 (1%) 

Urinary bladder (99) (96) (100) (100) (99) 

Edema 2 (2%) 1 (1%) 

Hemorrhage 1 (1%) 

Infiltration cellular, lymphocyte 4 (4%) 6 (6%) 3 (3%) 6 (6%) 7 (7%) 

Inflammation, acute 3 (3%) 

Inflammation, chronic 2 (2%) 1 (1%) 1 (1%) 

Ulcer 1 (1%) 

Transitional epithelium, hyperplasia 1 (1%) 1 (1%) 2 (2%) 

 


 


 


 

83 

APPENDIX B
 

SUMMARY OF LESIONS IN FEMALE RATS
 

IN THE 2-YEAR WHOLE-BODY EXPOSURE STUDY
 

OF 60-HZ MAGNETIC FIELDS
 

TABLE B1 Summary of the Incidence of Neoplasms in Female Rats 

in the 2-Year Whole-Body Exposure Study of 60-Hz Magnetic Fields .............. 84 

TABLE B2 Statistical Analysis of Primary Neoplasms in Female Rats 

in the 2-Year Whole-Body Exposure Study of 60-Hz Magnetic Fields .............. 88 

TABLE B3 Summary of the Incidence of Nonneoplastic Lesions in Female Rats 

in the 2-Year Whole-Body Exposure Study of 60-Hz Magnetic Fields .............. 92 
 

 

 

 

 

 

 

 

 

 

 

 

 

84 60-Hz Magnetic Fields, NTP TR 488 

TABLE B1 

Summary of the Incidence of Neoplasms in Female Rats in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fieldsa 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Disposition Summary 

Animals initially in study 100 100 100 100 100 

Early deaths 

Moribund 22 15 22 19 23 

Natural deaths 18 17 18 19 19 

Other 1 1 

Survivors 

Died last week of study 1 2 2 

Terminal sacrifice 58 66 60 59 58 

Animals examined microscopically 100 100 100 100 100 

Alimentary System 

Intestine large, colon (100) (100) (100) (100) (97) 

Polyp adenomatous 1 (1%) 

Intestine large, rectum (99) (100) (100) (99) (100) 

Sarcoma 1 (1%) 

Schwannoma malignant, metastatic, uterus 1 (1%) 

Intestine large, cecum (100) (98) (99) (100) (96) 

Intestine small, duodenum (97) (97) (96) (100) (96) 

Intestine small, ileum (94) (91) (93) (97) (91) 

Liver (100) (100) (100) (100) (100) 

Hemangiosarcoma, metastatic, spleen 1 (1%) 

Hepatocellular adenoma 1 (1%) 1 (1%) 

Schwannoma malignant, metastatic, uterus 1 (1%) 

Mesentery (11) (6) (5) (13) (16) 

Histiocytic sarcoma, metastatic, skin 1 (17%) 

Leiomyoma 1 (8%) 

Schwannoma malignant, metastatic, uterus 1 (9%) 

Pancreas (100) (100) (99) (100) (99) 

Acinus, adenoma 1 (1%) 1 (1%) 

Salivary glands (100) (99) (100) (100) (100) 

Stomach, forestomach (100) (99) (99) (100) (100) 

Squamous cell papilloma 1 (1%) 

Stomach, glandular (100) (100) (99) (100) (100) 

Tooth (2) (1) (1) (1) (1) 

Odontoma, multiple 1 (100%) 

Cardiovascular System 

Heart (100) (100) (100) (100) (100) 

Carcinosarcoma, metastatic, lung 1 (1%) 

Schwannoma malignant 1 (1%) 2 (2%) 2 (2%) 

Endocrine System 

Adrenal cortex (100) (100) (100) (100) (100) 

Adenoma 6 (6%) 2 (2%) 3 (3%) 1 (1%) 

Carcinoma 1 (1%) 1 (1%) 

Adrenal medulla (96) (94) (94) (98) (97) 

Pheochromocytoma malignant 1 (1%) 1 (1%) 

Pheochromocytoma complex 2 (2%) 

Pheochromocytoma benign 7 (7%) 8 (9%) 3 (3%) 2 (2%) 3 (3%) 

Bilateral, pheochromocytoma benign 1 (1%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

60-Hz Magnetic Fields, NTP TR 488 85 

TABLE B1 

Summary of the Incidence of Neoplasms in Female Rats in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Endocrine System (continued) 

Islets, pancreatic (100) (100) (99) (100) (99) 

Adenoma 1 (1%) 3 (3%) 1 (1%) 1 (1%) 

Carcinoma 1 (1%) 1 (1%) 1 (1%) 1 (1%) 1 (1%) 

Parathyroid gland (88) (94) (91) (88) (92) 

Adenoma 1 (1%) 1 (1%) 

Pituitary gland (99) (99) (98) (98) (98) 

Pars distalis, adenoma 61 (62%) 59 (60%) 68 (69%) 51 (52%) 62 (63%) 

Pars distalis, carcinoma 3 (3%) 1 (1%) 4 (4%) 2 (2%) 2 (2%) 

Pars intermedia, adenoma 3 (3%) 1 (1%) 

Thyroid gland (100) (100) (100) (100) (100) 

Bilateral, C-cell, adenoma 1 (1%) 1 (1%) 1 (1%) 1 (1%) 1 (1%) 

C-cell, adenoma 14 (14%) 19 (19%) 18 (18%) 19 (19%) 15 (15%) 

C-cell, carcinoma 5 (5%) 3 (3%) 3 (3%) 3 (3%) 6 (6%) 

Follicular cell, adenoma 1 (1%) 

General Body System 

Tissue NOS (2) 

Abdominal, chemodectoma benign 1 (50%) 

Nasal, schwannoma malignant 1 (50%) 

Genital System 

Clitoral gland (90) (96) (97) (96) (94) 

Adenoma 9 (10%) 13 (14%) 10 (10%) 15 (16%) 11 (12%) 

Hemangiosarcoma 1 (1%) 

Bilateral, adenoma 2 (2%) 2 (2%) 1 (1%) 1 (1%) 

Ovary (100) (100) (100) (100) (99) 

Granulosa cell tumor malignant 1 (1%)

 Granulosa cell tumor benign 1 (1%) 

Granulosa-theca tumor benign 1 (1%) 

Luteoma 1 (1%) 

Tubulostromal adenoma 3 (3%) 1 (1%) 2 (2%) 1 (1%) 1 (1%) 

Bilateral, granulosa cell tumor benign 1 (1%) 1 (1%) 

Bilateral, tubulostromal adenoma 1 (1%) 1 (1%) 

Uterus (100) (100) (100) (100) (99) 

Fibroma 1 (1%) 

Leiomyosarcoma 2 (2%) 1 (1%) 

Schwannoma malignant 2 (2%) 

Cervix, polyp stromal 1 (1%) 

Cervix, schwannoma malignant 1 (1%) 

Endometrium, adenoma 2 (2%) 

Endometrium, deciduoma malignant 1 (1%) 

Endometrium, polyp stromal 13 (13%) 10 (10%) 13 (13%) 13 (13%) 10 (10%) 

Endometrium, polyp stromal, multiple 1 (1%) 2 (2%) 

Endometrium, sarcoma stromal 2 (2%) 

Vagina (1) (1) (2) (2) 

Leiomyoma 1 (50%) 

Polyp 1 (50%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

86 60-Hz Magnetic Fields, NTP TR 488 

TABLE B1 

Summary of the Incidence of Neoplasms in Female Rats in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Hematopoietic System 

Bone marrow (100) (100) (100) (100) (100) 

Lymph node (16) (5) (5) (10) (18) 

Deep cervical, sarcoma, metastatic, skin 1 (6%) 

Lymph node, mandibular (100) (99) (100) (100) (100) 

Lymph node, mesenteric (100) (99) (99) (99) (99) 

Hemangiosarcoma 1 (1%) 

Spleen (100) (100) (100) (100) (99) 

Hemangiosarcoma 1 (1%) 

Thymus (95) (95) (92) (91) (92) 

Thymoma benign 1 (1%) 1 (1%) 1 (1%) 

Integumentary System 

Mammary gland (100) (100) (100) (100) (100) 

Adenoma 1 (1%) 2 (2%) 1 (1%) 1 (1%) 2 (2%) 

Carcinoma 2 (2%) 7 (7%) 5 (5%) 1 (1%) 2 (2%) 

Carcinoma, multiple 1 (1%) 

Fibroadenoma 36 (36%) 42 (42%) 32 (32%) 40 (40%) 27 (27%) 

Fibroadenoma, multiple 20 (20%) 20 (20%) 22 (22%) 24 (24%) 24 (24%) 

Skin (100) (100) (100) (100) (100) 

Basal cell adenoma 1 (1%) 1 (1%) 

Hemangiopericytoma 1 (1%) 

Keratoacanthoma 1 (1%) 1 (1%) 2 (2%) 1 (1%) 

Squamous cell papilloma 1 (1%) 

Trichoepithelioma 2 (2%) 

Lip, basal cell adenoma 1 (1%) 

Lip, squamous cell papilloma 1 (1%) 

Subcutaneous tissue, fibroma 4 (4%) 5 (5%) 4 (4%) 1 (1%) 

Subcutaneous tissue, fibrosarcoma 1 (1%) 2 (2%) 1 (1%) 

Subcutaneous tissue, hemangiosarcoma 1 (1%) 

Subcutaneous tissue, histiocytic sarcoma 1 (1%) 

Subcutaneous tissue, lipoma 1 (1%) 

Subcutaneous tissue, sarcoma 1 (1%) 

Subcutaneous tissue, schwannoma malignant 1 (1%) 1 (1%) 

Musculoskeletal System 

Bone (100) (100) (100) (100) (100) 

Vertebra, osteosarcoma 1 (1%) 

Nervous System 

Brain (100) (100) (100) (100) (100) 

Cerebellum, meningioma malignant 1 (1%) 

Cerebellum, meninges, granular cell tumor

 malignant 1 (1%) 

Cerebrum, astrocytoma malignant 1 (1%) 2 (2%) 

Cerebrum, glioma malignant 1 (1%) 

Meninges, granular cell tumor benign 2 (2%) 

Spinal cord (3) (4) (4) (1) (2) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

60-Hz Magnetic Fields, NTP TR 488 87 

TABLE B1 

Summary of the Incidence of Neoplasms in Female Rats in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Respiratory System 

Lung (100) (100) (100) (100) (100) 

Alveolar/bronchiolar adenoma 3 (3%) 5 (5%) 5 (5%) 1 (1%) 

Alveolar/bronchiolar carcinoma 1 (1%) 

Carcinoma, metastatic, Zymbal’s gland 1 (1%) 

Carcinosarcoma 1 (1%) 

Chordoma, metastatic, uncertain primary site 1 (1%) 

Osteosarcoma, metastatic, bone 1 (1%) 

Pheochromocytoma malignant, metastatic,

 adrenal medulla 1 (1%) 

Nose (100) (100) (100) (100) (100) 

Special Senses System 

Harderian gland (100) (100) (100) (100) (100) 

Zymbal’s gland (1) (1) 

Carcinoma 1 (100%) 1 (100%) 

Urinary System 

Kidney (100) (100) (100) (100) (100) 

Nephroblastoma 1 (1%) 

Schwannoma malignant, metastatic, uterus 1 (1%) 

Renal tubule, adenoma 1 (1%) 

Urinary bladder (99) (97) (99) (99) (96) 

Transitional epithelium, carcinoma 1 (1%) 1 (1%) 

Systemic Lesions 

Multiple organsb (100) (100) (100) (100) (100) 

Histiocytic sarcoma 1 (1%) 

Leukemia granulocytic 1 (1%) 

Leukemia mononuclear 20 (20%) 18 (18%) 24 (24%) 25 (25%) 22 (22%) 

Lymphoma malignant 1 (1%) 

Mesothelioma malignant 1 (1%) 

Neoplasm Summary 

Total animals with primary neoplasmsc 98 97 95 91 94 

Total primary neoplasms 227 247 244 224 212 

Total animals with benign neoplasms 92 94 87 85 86 

Total benign neoplasms 184 206 199 180 169 

Total animals with malignant neoplasms 40 41 38 39 40 

Total malignant neoplasms 43 41 45 44 43

 Total animals with metastatic neoplasms 3 3 2 1 1 

Total metastatic neoplasms 6 3 2 1 1

 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 

Primary neoplasms: all neoplasms except metastatic neoplasms c 

 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 

88 60-Hz Magnetic Fields, NTP TR 488 

TABLE B2 

Statistical Analysis of Primary Neoplasms in Female Rats in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Adrenal Cortex: Adenoma 

Overall ratea 6/100 (6%) 2/100 (2%) 3/100 (3%) 1/100 (1%) 0/100 (0%) 

Adjusted rateb 7.0% 2.2% 3.4% 1.2% 0.0% 

Terminal ratec 4/59 (7%) 2/68 (3%) 3/60 (5%) 1/61 (2%) 0/58 (0%) e First incidence (days) 597 737 (T) 737 (T) 737 (T) —
 

Poly-3 testd P=0.139N P=0.127N P=0.240N P=0.062N P=0.020N
 

Adrenal Cortex: Adenoma or Carcinoma 

Overall rate 7/100 (7%) 2/100 (2%) 4/100 (4%) 1/100 (1%) 0/100 (0%)
 

Adjusted rate 8.1% 2.2% 4.6% 1.2% 0.0%
 

Terminal rate 4/59 (7%) 2/68 (3%) 4/60 (7%) 1/61 (2%) 0/58 (0%)
 

First incidence (days) 597 737 (T) 737 (T) 737 (T) —
 

Poly-3 test P=0.103N P=0.077N P=0.260N P=0.036N P=0.011N
 

Adrenal Medulla: Benign Pheochromocytoma 

Overall rate 7/96 (7%) 8/94 (9%) 4/94 (4%) 2/98 (2%) 3/97 (3%) 

Adjusted rate 8.5% 9.5% 4.8% 2.4% 3.7% 

Terminal rate 6/56 (11%) 6/63 (10%) 0/56 (0%) 1/60 (2%) 2/58 (3%) 

First incidence (days) 655 590 648 715 727 

Poly-3 test P=0.045N P=0.521 P=0.263N P=0.081N P=0.164N 

Adrenal Medulla: Benign, Complex, or Malignant Pheochromocytoma 

Overall rate 7/96 (7%) 9/94 (10%) 5/94 (5%) 2/98 (2%) 5/97 (5%) 

Adjusted rate 8.5% 10.6% 6.0% 2.4% 6.1% 

Terminal rate 6/56 (11%) 6/63 (10%) 0/56 (0%) 1/60 (2%) 3/58 (5%) 

First incidence (days) 655 583 647 715 645 

Poly-3 test P=0.033N P=0.423 P=0.376N P=0.081N P=0.381N 

Clitoral Gland: Adenoma 

Overall rate 11/90 (12%) 15/96 (16%) 11/97 (11%) 16/96 (17%) 11/94 (12%)
 

Adjusted rate 14.1% 17.5% 13.0% 19.5% 13.5%
 

Terminal rate 7/56 (13%) 15/65 (23%) 10/58 (17%) 14/59 (24%) 8/56 (14%)
 

First incidence (days) 597 737 (T) 647 651 430
 

Poly-3 test P=0.242 P=0.350 P=0.507N P=0.239 P=0.547N
 

Lung: Alveolar/bronchiolar Adenoma 

Overall rate 3/100 (3%) 5/100 (5%) 5/100 (5%) 1/100 (1%) 0/100 (0%)
 

Adjusted rate 3.5% 5.5% 5.7% 1.2% 0.0%
 

Terminal rate 3/59 (5%) 2/68 (3%) 3/60 (5%) 1/61 (2%) 0/58 (0%)
 

First incidence (days) 737 (T) 598 687 737 (T) —
 

Poly-3 test P=0.126N P=0.389 P=0.373 P=0.309N P=0.126N
 

Lung: Alveolar/bronchiolar Adenoma or Carcinoma 

Overall rate 4/100 (4%) 5/100 (5%) 5/100 (5%) 2/100 (2%) 0/100 (0%)
 

Adjusted rate 4.7% 5.5% 5.7% 2.4% 0.0%
 

Terminal rate 3/59 (5%) 2/68 (3%) 3/60 (5%) 2/61 (3%) 0/58 (0%)
 

First incidence (days) 610 598 687 737 (T) —
 

Poly-3 test P=0.209N P=0.530 P=0.513 P=0.344N P=0.068N
 

 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 

60-Hz Magnetic Fields, NTP TR 488 89 

TABLE B2 

Statistical Analysis of Primary Neoplasms in Female Rats in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Mammary Gland: Fibroadenoma 

Overall rate 56/100 (56%) 62/100 (62%) 54/100 (54%) 64/100 (64%) 51/100 (51%)
 

Adjusted rate 62.5% 67.0% 59.8% 71.8% 57.8%
 

Terminal rate 39/59 (66%) 49/68 (72%) 40/60 (67%) 45/61 (74%) 36/58 (62%)
 

First incidence (days) 543 522 557 522 430
 

Poly-3 test P=0.109 P=0.305 P=0.409N P=0.111 P=0.306N
 

Mammary Gland: Fibroadenoma or Adenoma 

Overall rate 56/100 (56%) 63/100 (63%) 55/100 (55%) 64/100 (64%) 52/100 (52%)
 

Adjusted rate 62.5% 67.9% 60.6% 71.8% 58.9%
 

Terminal rate 39/59 (66%) 49/68 (72%) 40/60 (67%) 45/61 (74%) 37/58 (64%)
 

First incidence (days) 543 522 557 522 430
 

Poly-3 test P=0.127 P=0.260 P=0.457N P=0.111 P=0.364N
 

Mammary Gland: Carcinoma 

Overall rate 2/100 (2%) 7/100 (7%) 5/100 (5%) 2/100 (2%) 2/100 (2%)
 

Adjusted rate 2.3% 7.8% 5.7% 2.4% 2.4%
 

Terminal rate 2/59 (3%) 4/68 (6%) 3/60 (5%) 2/61 (3%) 1/58 (2%)
 

First incidence (days) 737 (T) 589 656 737 (T) 591
 

Poly-3 test P=0.202N P=0.098 P=0.231 P=0.691 P=0.689
 

Mammary Gland: Adenoma or Carcinoma 

Overall rate 3/100 (3%) 8/100 (8%) 6/100 (6%) 3/100 (3%) 4/100 (4%)
 

Adjusted rate 3.5% 8.9% 6.8% 3.5% 4.8%
 

Terminal rate 3/59 (5%) 4/68 (6%) 3/60 (5%) 2/61 (3%) 3/58 (5%)
 

First incidence (days) 737 (T) 589 637 704 591
 

Poly-3 test P=0.231N P=0.125 P=0.263 P=0.659 P=0.493
 

Mammary Gland: Fibroadenoma, Adenoma, or Carcinoma 

Overall rate 58/100 (58%) 67/100 (67%) 55/100 (55%) 65/100 (65%) 54/100 (54%)
 

Adjusted rate 64.7% 71.7% 60.6% 72.9% 60.8%
 

Terminal rate 41/59 (70%) 51/68 (75%) 40/60 (67%) 46/61 (75%) 38/58 (66%)
 

First incidence (days) 543 522 557 522 430
 

Poly-3 test P=0.187 P=0.184 P=0.333N P=0.141 P=0.346N
 

Pituitary Gland (Pars Distalis): Adenoma 

Overall rate 61/99 (62%) 59/99 (60%) 68/98 (69%) 51/98 (52%) 62/98 (63%)
 

Adjusted rate 65.8% 62.5% 73.4% 58.4% 68.1%
 

Terminal rate 40/59 (68%) 36/67 (54%) 45/60 (75%) 34/61 (56%) 37/58 (64%)
 

First incidence (days) 533 563 429 522 430
 

Poly-3 test P=0.143N P=0.371N P=0.159 P=0.183N P=0.429
 

Pituitary Gland (Pars Distalis): Adenoma or Carcinoma 

Overall rate 64/99 (65%) 60/99 (61%) 72/98 (73%) 53/98 (54%) 64/98 (65%)
 

Adjusted rate 68.8% 63.5% 77.4% 60.6% 70.1%
 

Terminal rate 42/59 (71%) 37/67 (55%) 47/60 (78%) 36/61 (59%) 38/58 (66%)
 

First incidence (days) 533 563 429 522 430
 

Poly-3 test P=0.138N P=0.266N P=0.114 P=0.153 P=0.492
 

 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 

90 60-Hz Magnetic Fields, NTP TR 488 

TABLE B2 

Statistical Analysis of Primary Neoplasms in Female Rats in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Skin: Squamous Cell Papilloma, Keratoacanthoma, Trichoepithelioma, or Basal Cell Adenoma 

Overall rate 1/100 (1%) 2/100 (2%) 6/100 (6%) 1/100 (1%) 2/100 (2%) 

Adjusted rate 1.2% 2.2% 6.9% 1.2% 2.4% 

Terminal rate 1/59 (2%) 2/68 (3%) 5/60 (8%) 1/61 (2%) 2/58 (3%) 

First incidence (days) 737 (T) 737 (T) 710 737 (T) 737 (T) 

Poly-3 test P=0.393N P=0.516 P=0.064 P=0.759 P=0.495 

Skin (Subcutaneous Tissue): Fibroma 

Overall rate 4/100 (4%) 5/100 (5%) 4/100 (4%) 0/100 (0%) 1/100 (1%) 

Adjusted rate 4.7% 5.6% 4.6% 0.0% 1.2% 

Terminal rate 2/59 (3%) 4/68 (6%) 1/60 (2%) 0/61 (0%) 1/58 (2%) 

First incidence (days) 660 711 652 — 737 (T) 

Poly-3 test P=0.035N P=0.525 P=0.629N P=0.065N P=0.192N 

Skin (Subcutaneous Tissue): Fibroma, Fibrosarcoma, or Sarcoma 

Overall rate 6/100 (6%) 5/100 (5%) 4/100 (4%) 2/100 (2%) 2/100 (2%)
 

Adjusted rate 6.9% 5.6% 4.6% 2.4% 2.4%
 

Terminal rate 2/59 (3%) 4/68 (6%) 1/60 (2%) 2/61 (3%) 1/58 (2%)
 

First incidence (days) 613 711 652 737 (T) 602
 

Poly-3 test P=0.140N P=0.477N P=0.362N P=0.144N P=0.148N
 

Thyroid Gland (C-cell): Adenoma 

Overall rate 15/100 (15%) 20/100 (20%) 19/100 (19%) 20/100 (20%) 16/100 (16%)
 

Adjusted rate 17.3% 22.0% 21.4% 23.5% 19.0%
 

Terminal rate 12/59 (20%) 16/68 (24%) 14/60 (23%) 17/61 (28%) 14/58 (24%)
 

First incidence (days) 561 522 497 673 632
 

Poly-3 test P=0.292 P=0.271 P=0.311 P=0.205 P=0.463
 

Thyroid Gland (C-cell): Carcinoma 

Overall rate 5/100 (5%) 3/100 (3%) 3/100 (3%) 3/100 (3%) 6/100 (6%)
 

Adjusted rate 5.9% 3.4% 3.4% 3.5% 7.1%
 

Terminal rate 4/59 (7%) 3/68 (4%) 1/60 (2%) 1/61 (2%) 5/58 (9%)
 

First incidence (days) 710 737 (T) 665 557 627
 

Poly-3 test P=0.463N P=0.335N P=0.344N P=0.357N P=0.489
 

Thyroid Gland (C-cell): Adenoma or Carcinoma 

Overall rate 19/100 (19%) 22/100 (22%) 22/100 (22%) 23/100 (23%) 22/100 (22%)
 

Adjusted rate 21.9% 24.3% 24.6% 26.8% 26.1%
 

Terminal rate 15/59 (25%) 18/68 (27%) 15/60 (25%) 18/61 (30%) 19/58 (33%)
 

First incidence (days) 561 522 497 557 627
 

Poly-3 test P=0.305 P=0.422 P=0.401 P=0.283 P=0.322
 

Uterus: Stromal Polyp 

Overall rate 13/100 (13%) 11/100 (11%) 13/100 (13%) 13/100 (13%) 12/100 (12%)
 

Adjusted rate 15.1% 12.2% 14.6% 14.9% 14.2%
 

Terminal rate 9/59 (15%) 7/68 (10%) 6/60 (10%) 6/61 (10%) 10/58 (17%)
 

First incidence (days) 620 669 557 485 480
 

Poly-3 test P=0.457 P=0.370N P=0.548N P=0.569N P=0.525N
 
	 

	 

c 

60-Hz Magnetic Fields, NTP TR 488 91 

TABLE B2 

Statistical Analysis of Primary Neoplasms in Female Rats in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Uterus: Stromal Polyp or Stromal Sarcoma 

Overall rate 13/100 (13%) 12/100 (12%) 13/100 (13%) 13/100 (13%) 12/100 (12%) 

Adjusted rate 15.1% 13.3% 14.6% 14.9% 14.2% 

Terminal rate 9/59 (15%) 8/68 (12%) 6/60 (10%) 6/61 (10%) 10/58 (17%) 

First incidence (days) 620 669 557 485 480 

Poly-3 test P=0.501 P=0.455N P=0.548N P=0.569N P=0.525N 

All Organs: Mononuclear Cell Leukemia 

Overall rate 20/100 (20%) 18/100 (18%) 24/100 (24%) 25/100 (25%) 22/100 (22%) 

Adjusted rate 22.7% 19.6% 26.4% 28.8% 25.5% 

Terminal rate 11/59 (19%) 11/68 (16%) 11/60 (18%) 16/61 (26%) 12/58 (21%) 

First incidence (days) 495 498 488 579 526 

Poly-3 test P=0.121 P=0.375N P=0.342 P=0.223 P=0.398 

All Organs: Benign Neoplasms 

Overall rate 92/100 (92%) 94/100 (94%) 87/100 (87%) 85/100 (85%) 86/100 (86%) 

Adjusted rate 95.6% 96.2% 90.8% 91.6% 91.3% 

Terminal rate 58/59 (98%) 66/68 (97%) 57/60 (95%) 57/61 (93%) 55/58 (95%) 

First incidence (days) 533 508 429 485 430 

Poly-3 test P=0.131N P=0.564 P=0.124N P=0.182N P=0.145N 

All Organs: Malignant Neoplasms 

Overall rate 40/100 (40%) 41/100 (41%) 38/100 (38%) 39/100 (39%) 40/100 (40%) 

Adjusted rate 43.4% 43.4% 41.3% 44.1% 44.7% 

Terminal rate 22/59 (37%) 25/68 (37%) 19/60 (32%) 24/61 (39%) 22/58 (38%) 

First incidence (days) 462 498 488 409 480 

Poly-3 test P=0.477 P=0.555N P=0.443N P=0.523 P=0.490 

All Organs: Benign or Malignant Neoplasms 

Overall rate 98/100 (98%) 97/100 (97%) 95/100 (95%) 91/100 (91%) 94/100 (94%) 

Adjusted rate 99.1% 97.6% 97.6% 96.9% 96.5% 

Terminal rate 59/59 (100%) 66/68 (97%) 60/60 (100%) 59/61 (97%) 56/58 (97%) 

First incidence (days) 462 498 429 409 430 

Poly-3 test P=0.305N P=0.371N P=0.349N P=0.234N P=0.179N 

(T)Terminal sacrifice 

a Number of neoplasm-bearing animals/number of animals examined. Denominator is number of animals examined microscopically for adrenal gland, clitoral 

gland, lung, pituitary gland, and thyroid gland; for other tissues, denominator is number of animals necropsied. b	 Poly-3 estimated neoplasm incidence after adjustment for intercurrent mortality 

Observed incidence at terminal kill 

d	 Beneath the control incidence are the P values associated with the trend test; the trend does not include the 10 G intermittent group. 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 negative trend or a lower incidence in an exposure group is indicated by N. e Not applicable; no neoplasms in animal group 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

92 60-Hz Magnetic Fields, NTP TR 488 

TABLE B3 

Summary of the Incidence of Nonneoplastic Lesions in Female Rats in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fieldsa 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Disposition Summary 

Animals initially in study 100 100 100 100 100 

Early deaths 

Moribund 22 15 22 19 23 

Natural deaths 18 17 18 19 19 

Other 1 1 

Survivors 

Died last week of study 1 2 2 

Terminal sacrifice 58 66 60 59 58 

Animals examined microscopically 100 100 100 100 100 

Alimentary System 

Intestine large, colon (100) (100) (100) (100) (97) 

Inflammation, chronic active 1 (1%) 

Intestine large, rectum (99) (100) (100) (99) (100) 

Inflammation, chronic 1 (1%) 

Inflammation, chronic active 1 (1%) 

Intestine large, cecum (100) (98) (99) (100) (96) 

Epithelium, hyperplasia 1 (1%) 

Intestine small, duodenum (97) (97) (96) (100) (96) 

Diverticulum 1 (1%) 

Ectopic tissue 1 (1%) 1 (1%) 

Intestine small, ileum (94) (91) (93) (97) (91) 

Ulcer 1 (1%) 

Peyer’s patch, hyperplasia, lymphoid 2 (2%) 

Serosa, inflammation, chronic 1 (1%) 

Liver (100) (100) (100) (100) (100) 

Angiectasis, focal 1 (1%) 1 (1%) 2 (2%) 3 (3%) 

Basophilic focus 66 (66%) 82 (82%) 77 (77%) 66 (66%) 78 (78%) 

Clear cell focus 6 (6%) 13 (13%) 18 (18%) 13 (13%) 18 (18%) 

Congestion 1 (1%) 

Eosinophilic focus 18 (18%) 24 (24%) 30 (30%) 24 (24%) 31 (31%) 

Fibrosis 2 (2%) 1 (1%) 1 (1%) 1 (1%) 

Hematopoietic cell proliferation 6 (6%) 3 (3%) 2 (2%) 4 (4%) 2 (2%) 

Hepatodiaphragmatic nodule 8 (8%) 4 (4%) 4 (4%) 5 (5%) 6 (6%) 

Infiltration cellular, lymphocyte 1 (1%) 1 (1%) 4 (4%) 2 (2%) 

Infiltration cellular, histiocyte 2 (2%) 1 (1%) 

Infiltration cellular, mixed cell 32 (32%) 40 (40%) 37 (37%) 28 (28%) 27 (27%) 

Inflammation, chronic 1 (1%) 1 (1%) 2 (2%) 2 (2%) 2 (2%) 

Inflammation, chronic active 1 (1%) 

Inflammation, granulomatous 2 (2%) 

Mixed cell focus 39 (39%) 45 (45%) 49 (49%) 42 (42%) 37 (37%) 

Necrosis 3 (3%) 4 (4%) 7 (7%) 4 (4%) 4 (4%) 

Pigmentation 1 (1%) 

Tension lipidosis, focal 1 (1%) 1 (1%) 1 (1%) 

Bile duct, hyperplasia 28 (28%) 20 (20%) 31 (31%) 21 (21%) 24 (24%) 

Hepatocyte, hypertrophy 1 (1%) 

Hepatocyte, vacuolization cytoplasmic 11 (11%) 12 (12%) 9 (9%) 11 (11%) 9 (9%) 

Mesentery (11) (6) (5) (13) (16) 

Accessory spleen 1 (9%) 1 (8%) 

Fat, necrosis 9 (82%) 4 (67%) 4 (80%) 10 (77%) 15 (94%) 

a Number of animals examined microscopically at the site and the number of animals with lesion 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

60-Hz Magnetic Fields, NTP TR 488 93 

TABLE B3 

Summary of the Incidence of Nonneoplastic Lesions in Female Rats in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Alimentary System (continued) 

Pancreas (100) (100) (99) (100) (99) 

Infiltration cellular, lymphocyte 14 (14%) 10 (10%) 9 (9%) 9 (9%) 7 (7%) 

Metaplasia, hepatocyte 2 (2%) 

Acinus, atrophy, diffuse 3 (3%) 1 (1%) 2 (2%) 

Acinus, atrophy, focal 15 (15%) 18 (18%) 26 (26%) 16 (16%) 20 (20%) 

Acinus, basophilic focus 2 (2%) 

Acinus, hyperplasia, focal 3 (3%) 5 (5%) 5 (5%) 1 (1%) 2 (2%) 

Artery, inflammation, chronic 1 (1%) 

Duct, hyperplasia 1 (1%) 1 (1%) 

Salivary glands (100) (99) (100) (100) (100) 

Pigmentation 1 (1%) 

Duct, parotid gland, hyperplasia 1 (1%) 

Duct, parotid gland, mineralization 1 (1%) 

Duct, sublingual gland, metaplasia, squamous 1 (1%) 2 (2%) 

Parotid gland, atrophy 3 (3%) 2 (2%) 3 (3%) 2 (2%) 2 (2%) 

Parotid gland, hyperplasia 1 (1%) 1 (1%) 

Parotid gland, inflammation, acute 1 (1%) 

Parotid gland, inflammation, chronic 1 (1%) 

Sublingual gland, atrophy 1 (1%) 1 (1%) 1 (1%) 1 (1%) 

Sublingual gland, infiltration cellular,

 lymphocyte 1 (1%) 

Sublingual gland, metaplasia, squamous 1 (1%) 

Submandibular gland, infiltration cellular,

 lymphocyte 1 (1%) 

Stomach, forestomach (100) (99) (99) (100) (100) 

Edema 3 (3%) 1 (1%) 3 (3%) 

Erosion, focal 1 (1%) 

Inflammation, acute 1 (1%) 1 (1%) 1 (1%) 

Inflammation, chronic 1 (1%) 1 (1%) 

Inflammation, chronic active 1 (1%) 2 (2%) 

Ulcer 3 (3%) 1 (1%) 3 (3%) 1 (1%) 

Epithelium, hyperplasia 7 (7%) 2 (2%) 3 (3%) 10 (10%) 

Stomach, glandular (100) (100) (99) (100) (100) 

Edema 1 (1%) 1 (1%) 

Erosion, focal 5 (5%) 2 (2%) 2 (2%) 5 (5%) 3 (3%) 

Fibrosis 1 (1%) 

Inflammation, chronic active 1 (1%) 

Metaplasia, focal, squamous 1 (1%) 

Necrosis, focal 1 (1%) 

Glands, congestion 1 (1%) 

Glands, cyst 12 (12%) 20 (20%) 26 (26%) 12 (12%) 12 (12%) 

Muscularis, mineralization 1 (1%) 

Tongue (1) (1) (2) (1) 

Epithelium, hyperplasia, focal 1 (100%) 1 (100%) 1 (50%) 1 (100%) 

Tooth (2) (1) (1) (1) (1) 

Inflammation, chronic 1 (100%) 

Malformation 1 (50%) 1 (100%) 

Necrosis 1 (100%) 

Gingiva, inflammation, chronic active 1 (100%) 

Peridontal tissue, inflammation, chronic

 active 1 (50%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

94 60-Hz Magnetic Fields, NTP TR 488 

TABLE B3 

Summary of the Incidence of Nonneoplastic Lesions in Female Rats in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Cardiovascular System 

Blood vessel (99) (100) (100) (100) (100) 

Inflammation, chronic 1 (1%) 

Heart (100) (100) (100) (100) (100) 

Cardiomyopathy 53 (53%) 71 (71%) 64 (64%) 61 (61%) 60 (60%) 

Artery, inflammation, chronic 1 (1%) 

Atrium, mineralization 1 (1%) 

Atrium, thrombosis 1 (1%) 2 (2%) 

Endocardium, inflammation, chronic 1 (1%) 

Myocardium, fibrosis, focal 1 (1%) 

Endocrine System 

Adrenal cortex (100) (100) (100) (100) (100) 

Angiectasis 1 (1%) 4 (4%) 4 (4%) 1 (1%) 5 (5%) 

Degeneration 1 (1%) 1 (1%) 

Hematopoietic cell proliferation 1 (1%) 2 (2%) 4 (4%) 2 (2%) 

Hemorrhage 1 (1%) 

Hyperplasia, focal 11 (11%) 23 (23%) 12 (12%) 8 (8%) 15 (15%) 

Hypertrophy, focal 3 (3%) 1 (1%) 5 (5%) 1 (1%) 

Infiltration cellular, lymphocyte 1 (1%) 

Inflammation, chronic 1 (1%) 

Mineralization 1 (1%) 1 (1%) 

Necrosis 1 (1%) 2 (2%) 1 (1%) 1 (1%) 

Vacuolization cytoplasmic, diffuse 1 (1%) 2 (2%) 1 (1%) 

Vacuolization cytoplasmic, focal 27 (27%) 27 (27%) 24 (24%) 31 (31%) 24 (24%) 

Bilateral, angiectasis 57 (57%) 51 (51%) 46 (46%) 58 (58%) 57 (57%) 

Bilateral, hematopoietic cell proliferation 2 (2%) 3 (3%) 4 (4%) 2 (2%) 

Bilateral, hyperplasia, focal 1 (1%) 2 (2%) 1 (1%) 

Bilateral, infiltration cellular, lymphocyte 1 (1%) 

Bilateral, infiltration cellular, mixed cell 1 (1%) 1 (1%) 

Bilateral, inflammation, chronic 1 (1%) 1 (1%) 

Bilateral, necrosis 1 (1%) 1 (1%) 

Bilateral, pigmentation 2 (2%) 2 (2%) 

Bilateral, vacuolization cytoplasmic, diffuse 1 (1%) 

Bilateral, vacuolization cytoplasmic, focal 2 (2%) 3 (3%) 2 (2%) 3 (3%) 3 (3%) 

Adrenal medulla (96) (94) (94) (98) (97) 

Hyperplasia, focal 6 (6%) 6 (6%) 4 (4%) 7 (7%) 4 (4%) 

Bilateral, hyperplasia, focal 1 (1%) 

Bilateral, infiltration cellular, lymphocyte 1 (1%) 1 (1%) 

Bilateral, necrosis 1 (1%) 

Islets, pancreatic (100) (100) (99) (100) (99) 

Hyperplasia, focal 1 (1%) 1 (1%) 

Parathyroid gland (88) (94) (91) (88) (92) 

Cyst 1 (1%) 1 (1%) 

Degeneration 1 (1%) 

Hyperplasia, focal 1 (1%) 

Pineal gland (85) (90) (85) (90) (89) 

Fibrosis 1 (1%) 

Infiltration cellular, lymphocyte 1 (1%) 

Mineralization 56 (66%) 54 (60%) 57 (67%) 54 (60%) 40 (45%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

60-Hz Magnetic Fields, NTP TR 488 95 

TABLE B3 

Summary of the Incidence of Nonneoplastic Lesions in Female Rats in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Endocrine System (continued) 

Pituitary gland (99) (99) (98) (98) (98) 

Pars distalis, angiectasis 1 (1%) 1 (1%) 

Pars distalis, angiectasis, focal 1 (1%) 9 (9%) 5 (5%) 3 (3%) 2 (2%) 

Pars distalis, cyst 21 (21%) 21 (21%) 19 (19%) 28 (29%) 25 (26%) 

Pars distalis, degeneration, focal 1 (1%) 

Pars distalis, hyperplasia, diffuse 1 (1%) 

Pars distalis, hyperplasia, focal 10 (10%) 9 (9%) 6 (6%) 6 (6%) 7 (7%) 

Pars distalis, hypertrophy, focal 1 (1%) 1 (1%) 

Pars distalis, inflammation, chronic 2 (2%) 1 (1%) 1 (1%) 

Pars distalis, pigmentation 2 (2%) 1 (1%) 2 (2%) 1 (1%) 

Pars intermedia, hyperplasia, focal 1 (1%) 1 (1%) 1 (1%) 

Rathke’s cleft, cyst 2 (2%) 2 (2%) 

Rathke’s cleft, hemorrhage 1 (1%) 

Rathke’s cleft, pigmentation 1 (1%) 1 (1%) 1 (1%) 

Thyroid gland (100) (100) (100) (100) (100) 

Infiltration cellular, lymphocyte 1 (1%) 

Ultimobranchial cyst 2 (2%) 4 (4%) 7 (7%) 3 (3%) 3 (3%) 

C-cell, hyperplasia 18 (18%) 5 (5%) 

C-cell, hyperplasia, diffuse 2 (2%) 1 (1%) 3 (3%) 2 (2%) 

C-cell, hyperplasia, focal 20 (20%) 39 (39%) 52 (52%) 24 (24%) 30 (30%) 

Follicle, cyst 1 (1%) 1 (1%) 1 (1%) 1 (1%) 

Follicular cell, hyperplasia, focal 1 (1%) 1 (1%) 

General Body System 

None 

Genital System 

Clitoral gland (90) (96) (97) (96) (94) 

Cyst 1 (1%) 7 (7%) 1 (1%) 3 (3%) 

Hyperplasia, focal 6 (7%) 4 (4%) 3 (3%) 5 (5%) 5 (5%) 

Inflammation, acute 1 (1%) 1 (1%) 

Inflammation, chronic 15 (17%) 9 (9%) 13 (13%) 23 (24%) 12 (13%) 

Inflammation, chronic active 7 (7%) 2 (2%) 5 (5%) 1 (1%) 

Bilateral, atrophy 1 (1%) 

Bilateral, inflammation, chronic 8 (9%) 2 (2%) 4 (4%) 2 (2%) 7 (7%) 

Bilateral, inflammation, chronic active 2 (2%) 2 (2%) 

Ovary (100) (100) (100) (100) (99) 

Inflammation, chronic 1 (1%) 1 (1%) 1 (1%) 2 (2%) 

Mineralization 1 (1%) 

Bilateral, atrophy 1 (1%) 2 (2%) 1 (1%) 

Bilateral, inflammation, chronic 3 (3%) 2 (2%) 3 (3%) 1 (1%) 2 (2%) 

Bilateral, pigmentation 2 (2%) 

Bilateral, periovarian tissue, cyst 2 (2%) 

Bilateral, follicle, cyst 1 (1%) 

Bilateral, rete ovarii, hyperplasia 3 (3%) 2 (2%) 3 (3%) 1 (1%) 3 (3%) 

Follicle, cyst 3 (3%) 5 (5%) 1 (1%) 4 (4%) 2 (2%) 

Interstitial cell, hyperplasia 1 (1%) 

Periovarian tissue, cyst 6 (6%) 6 (6%) 12 (12%) 8 (8%) 11 (11%) 

Rete ovarii, hyperplasia 5 (5%) 14 (14%) 5 (5%) 14 (14%) 13 (13%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

96 60-Hz Magnetic Fields, NTP TR 488 

TABLE B3 

Summary of the Incidence of Nonneoplastic Lesions in Female Rats in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Genital System (continued) 

Uterus (100) (100) (100) (100) (99) 

Hemorrhage 1 (1%) 2 (2%) 

Hydrometra 9 (9%) 10 (10%) 8 (8%) 7 (7%) 6 (6%) 

Pigmentation 2 (2%) 1 (1%) 1 (1%) 1 (1%) 

Cervix, cyst 2 (2%) 

Cervix, inflammation, chronic active 2 (2%) 1 (1%) 1 (1%) 1 (1%) 

Cervix, epithelium, vacuolization cytoplasmic 1 (1%) 

Endometrium, angiectasis, focal 1 (1%) 

Endometrium, cyst 3 (3%) 3 (3%) 4 (4%) 1 (1%) 9 (9%) 

Endometrium, cytoplasmic alteration 1 (1%) 

Endometrium, fibrosis 1 (1%) 1 (1%) 2 (2%) 

Endometrium, hyperplasia 1 (1%) 

Endometrium, inflammation, acute 1 (1%) 

Endometrium, inflammation, chronic 1 (1%) 3 (3%) 3 (3%) 1 (1%) 

Endometrium, inflammation, chronic active 2 (2%) 

Endometrium, pigmentation 2 (2%) 1 (1%) 

Endometrium, epithelium, hyperplasia 1 (1%) 1 (1%) 

Serosa, fibrosis 1 (1%) 

Vagina (1) (1) (2) (2) 

Cyst 1 (50%) 

Hematopoietic System 

Bone marrow (100) (100) (100) (100) (100) 

Depletion cellular 9 (9%) 5 (5%) 6 (6%) 4 (4%) 11 (11%) 

Hyperplasia 13 (13%) 19 (19%) 13 (13%) 12 (12%) 17 (17%) 

Inflammation, chronic 1 (1%) 

Myelofibrosis 1 (1%) 1 (1%) 

Lymph node (16) (5) (5) (10) (18) 

Pigmentation 2 (13%) 

Inguinal, degeneration, cystic 1 (20%) 

Inguinal, hyperplasia, lymphoid 1 (6%) 1 (20%) 

Mediastinal, hemorrhage 1 (6%) 1 (20%) 1 (10%) 3 (17%) 

Mediastinal, pigmentation 1 (6%) 1 (20%) 

Pancreatic, infiltration cellular, histiocyte 1 (20%) 

Lymph node, mandibular (100) (99) (100) (100) (100) 

Atrophy 1 (1%) 

Congestion 2 (2%) 

Degeneration, cystic 11 (11%) 19 (19%) 4 (4%) 8 (8%) 15 (15%) 

Hemorrhage 1 (1%) 2 (2%) 3 (3%) 2 (2%) 3 (3%) 

Hyperplasia, lymphoid 13 (13%) 21 (21%) 11 (11%) 7 (7%) 7 (7%) 

Infiltration cellular, histiocyte 3 (3%) 1 (1%) 2 (2%) 1 (1%) 

Pigmentation 2 (2%) 2 (2%) 3 (3%) 

Lymph node, mesenteric (100) (99) (99) (99) (99) 

Angiectasis 1 (1%) 

Degeneration, cystic 2 (2%) 1 (1%) 1 (1%) 

Hemorrhage 3 (3%) 3 (3%) 2 (2%) 4 (4%) 4 (4%) 

Hyperplasia, lymphoid 1 (1%) 2 (2%) 

Infiltration cellular, histiocyte 85 (85%) 92 (93%) 86 (87%) 87 (88%) 86 (87%) 

Spleen (100) (100) (100) (100) (99) 

Congestion 1 (1%) 1 (1%) 

Depletion cellular, focal 1 (1%) 1 (1%) 2 (2%) 

Fibrosis 1 (1%) 2 (2%) 

Hematopoietic cell proliferation 15 (15%) 15 (15%) 20 (20%) 13 (13%) 28 (28%) 

Infiltration cellular, histiocyte 2 (2%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

60-Hz Magnetic Fields, NTP TR 488 97 

TABLE B3 

Summary of the Incidence of Nonneoplastic Lesions in Female Rats in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Hematopoietic System (continued) 

Spleen (continued) (100) (100) (100) (100) (99) 

Pigmentation 54 (54%) 48 (48%) 56 (56%) 57 (57%) 46 (46%) 

Capsule, fibrosis 1 (1%) 

Lymphoid follicle, atrophy 6 (6%) 3 (3%) 3 (3%) 4 (4%) 6 (6%) 

Lymphoid follicle, hyperplasia 1 (1%) 1 (1%) 

Thymus (95) (95) (92) (91) (92) 

Atrophy 51 (54%) 48 (51%) 47 (51%) 48 (53%) 43 (47%) 

Cyst 1 (1%) 3 (3%) 5 (5%) 2 (2%) 2 (2%) 

Ectopic parathyroid gland 1 (1%) 

Hemorrhage 2 (2%) 1 (1%) 3 (3%) 6 (7%) 5 (5%) 

Hyperplasia, lymphoid 1 (1%) 

Epithelial cell, hyperplasia 3 (3%) 1 (1%) 3 (3%) 4 (4%) 2 (2%) 

Integumentary System 

Mammary gland (100) (100) (100) (100) (100) 

Cyst 47 (47%) 54 (54%) 56 (56%) 61 (61%) 53 (53%) 

Fibrosis 2 (2%) 

Galactocele 10 (10%) 7 (7%) 14 (14%) 7 (7%) 10 (10%) 

Inflammation, chronic 1 (1%) 2 (2%) 2 (2%) 2 (2%) 

Mineralization 2 (2%) 

Epithelium, hyperplasia 1 (1%) 4 (4%) 3 (3%) 2 (2%) 3 (3%) 

Skin (100) (100) (100) (100) (100) 

Cyst epithelial inclusion 1 (1%) 1 (1%) 

Hyperkeratosis 1 (1%) 1 (1%) 

Hyperkeratosis, focal 1 (1%) 

Inflammation, chronic 1 (1%) 1 (1%) 1 (1%) 

Inflammation, chronic active 1 (1%) 1 (1%) 

Inflammation, chronic active, focal 1 (1%) 

Dermis, fibrosis, focal 1 (1%) 

Epidermis, hyperplasia, diffuse 1 (1%) 

Epidermis, lip, hyperplasia, focal 1 (1%) 

Nipple, hyperkeratosis 1 (1%) 

Subcutaneous tissue, inflammation, chronic 1 (1%) 

Subcutaneous tissue, necrosis 1 (1%) 

Musculoskeletal System 

Bone (100) (100) (100) (100) (100) 

Cranium, hyperostosis 7 (7%) 1 (1%) 5 (5%) 5 (5%) 2 (2%) 

Femur, hyperostosis 20 (20%) 10 (10%) 20 (20%) 18 (18%) 13 (13%) 

Intervertebral disc, degeneration 1 (1%) 

Maxilla, hyperostosis 1 (1%) 1 (1%) 

Turbinate, hyperostosis 7 (7%) 3 (3%) 9 (9%) 11 (11%) 6 (6%) 

Nervous System 

Brain (100) (100) (100) (100) (100) 

Mineralization 1 (1%) 

Cerebellum, gliosis, focal 1 (1%) 

Cerebellum, hemorrhage 2 (2%) 

Cerebrum, infiltration cellular, lymphocyte 1 (1%) 

Cerebrum, mineralization 2 (2%) 

Hypothalamus, compression 16 (16%) 9 (9%) 16 (16%) 15 (15%) 19 (19%) 

Pons, compression 2 (2%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

98 60-Hz Magnetic Fields, NTP TR 488 

TABLE B3 

Summary of the Incidence of Nonneoplastic Lesions in Female Rats in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Respiratory System 

Larynx (1) (1) (1) (1) (1) 

Inflammation, chronic 1 (100%) 

Lung (100) (100) (100) (100) (100) 

Congestion 5 (5%) 7 (7%) 4 (4%) 6 (6%) 7 (7%) 

Emphysema 1 (1%) 

Hemorrhage 1 (1%) 2 (2%) 1 (1%) 1 (1%) 

Infiltration cellular, lymphocyte 1 (1%) 6 (6%) 4 (4%) 7 (7%) 3 (3%) 

Infiltration cellular, histiocyte 31 (31%) 42 (42%) 34 (34%) 46 (46%) 35 (35%) 

Infiltration cellular, mixed cell 2 (2%) 5 (5%) 

Metaplasia, focal, osseous 1 (1%) 

Mineralization 1 (1%) 

Pigmentation 1 (1%) 1 (1%) 1 (1%) 

Alveolar epithelium, hyperplasia, focal 4 (4%) 3 (3%) 4 (4%) 1 (1%) 3 (3%) 

Interstitium, inflammation, chronic 10 (10%) 20 (20%) 13 (13%) 4 (4%) 7 (7%) 

Serosa, inflammation, chronic 1 (1%) 1 (1%) 

Nose (100) (100) (100) (100) (100) 

Inflammation, acute 1 (1%) 2 (2%) 

Inflammation, chronic 1 (1%) 2 (2%) 4 (4%) 1 (1%) 3 (3%) 

Inflammation, chronic active 8 (8%) 8 (8%) 7 (7%) 5 (5%) 7 (7%) 

Glands, cyst 1 (1%) 

Nasolacrimal duct, inflammation, acute 1 (1%) 2 (2%) 

Nasolacrimal duct, inflammation, chronic 2 (2%) 6 (6%) 4 (4%) 1 (1%) 7 (7%) 

Nasolacrimal duct, inflammation, chronic

 active 3 (3%) 2 (2%) 1 (1%) 

Olfactory epithelium, cytoplasmic alteration 69 (69%) 83 (83%) 87 (87%) 74 (74%) 77 (77%) 

Olfactory epithelium, mineralization, focal 1 (1%) 

Respiratory epithelium, cytoplasmic

 alteration 4 (4%) 1 (1%) 3 (3%) 5 (5%) 1 (1%) 

Trachea (100) (100) (100) (100) (100) 

Inflammation, chronic 6 (6%) 1 (1%) 7 (7%) 7 (7%) 5 (5%) 

Inflammation, chronic active 1 (1%) 

Glands, cyst 2 (2%) 

Special Senses System 

Eye (6) (4) (7) (6) (3) 

Atrophy 2 (29%) 1 (17%) 

Bilateral, cornea, mineralization 1 (33%) 

Bilateral, iris, synechia 1 (17%) 

Bilateral, lens, cataract 1 (17%) 1 (14%) 1 (17%) 

Bilateral, retina, atrophy 1 (17%) 1 (14%) 1 (17%) 

Cornea, inflammation, acute 1 (14%) 

Cornea, inflammation, chronic active 1 (17%) 

Iris, synechia 1 (17%) 

Lens, cataract 5 (83%) 4 (100%) 4 (57%) 3 (50%) 2 (67%) 

Retina, atrophy 5 (83%) 4 (100%) 4 (57%) 3 (50%) 2 (67%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

60-Hz Magnetic Fields, NTP TR 488 99 

TABLE B3 

Summary of the Incidence of Nonneoplastic Lesions in Female Rats in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Special Senses System (continued) 

Harderian gland (100) (100) (100) (100) (100) 

Atrophy, focal 1 (1%) 2 (2%) 2 (2%) 3 (3%) 

Cyst 1 (1%) 

Hyperplasia, focal 1 (1%) 2 (2%) 2 (2%) 

Infiltration cellular, lymphocyte 34 (34%) 33 (33%) 33 (33%) 28 (28%) 27 (27%) 

Inflammation, chronic 4 (4%) 3 (3%) 5 (5%) 6 (6%) 2 (2%) 

Mineralization 1 (1%) 

Pigmentation 1 (1%) 

Bilateral, infiltration cellular, lymphocyte 35 (35%) 40 (40%) 32 (32%) 28 (28%) 39 (39%) 

Bilateral, inflammation, chronic 6 (6%) 6 (6%) 11 (11%) 9 (9%) 12 (12%) 

Bilateral, inflammation, chronic active 1 (1%) 

Lacrimal gland (2) (1) (1) (4) 

Inflammation, chronic 1 (25%) 

Urinary System 

Kidney (100) (100) (100) (100) (100) 

Hydronephrosis 1 (1%) 

Infarct 1 (1%) 1 (1%) 1 (1%) 1 (1%) 

Infiltration cellular, lymphocyte 2 (2%) 1 (1%) 

Inflammation, chronic active 1 (1%) 

Mineralization 13 (13%) 12 (12%) 18 (18%) 11 (11%) 23 (23%) 

Bilateral, infiltration cellular, lymphocyte 1 (1%) 

Bilateral, mineralization 10 (10%) 12 (12%) 11 (11%) 6 (6%) 16 (16%) 

Bilateral, necrosis, chronic 1 (1%) 

Bilateral, nephropathy 54 (54%) 46 (46%) 69 (69%) 46 (46%) 51 (51%) 

Bilateral, pigmentation 2 (2%) 1 (1%) 

Bilateral, artery, hypertrophy 1 (1%) 

Bilateral, medulla, inflammation, chronic 1 (1%) 

Bilateral, pelvis, inflammation, acute 1 (1%) 

Bilateral, pelvis, inflammation, chronic 2 (2%) 1 (1%) 

Bilateral, pelvis, inflammation, chronic

 active 1 (1%) 

Bilateral, pelvis, transitional epithelium,

 hyperplasia 2 (2%) 

Bilateral, renal tubule, accumulation,

 hyaline droplet 5 (5%) 2 (2%) 3 (3%) 3 (3%) 

Bilateral, renal tubule, degeneration 2 (2%) 2 (2%) 1 (1%) 2 (2%) 3 (3%) 

Bilateral, renal tubule, dilatation 1 (1%) 

Bilateral, renal tubule, pigmentation 26 (26%) 11 (11%) 13 (13%) 30 (30%) 11 (11%) 

Capsule, fibrosis, focal 1 (1%) 

Pelvis, dilatation 1 (1%) 1 (1%) 

Pelvis, inflammation, acute 1 (1%) 

Pelvis, inflammation, chronic 2 (2%) 1 (1%) 2 (2%) 

Pelvis, inflammation, chronic active 3 (3%) 1 (1%) 

Pelvis, transitional epithelium, hyperplasia 2 (2%) 1 (1%) 1 (1%) 1 (1%) 

Renal tubule, hyperplasia, focal 1 (1%) 1 (1%) 

Renal tubule, necrosis 1 (1%) 

Urinary bladder (99) (97) (99) (99) (96) 

Calculus, microscopic observation only 1 (1%) 

Edema 1 (1%) 1 (1%) 

Infiltration cellular, lymphocyte 10 (10%) 9 (9%) 9 (9%) 5 (5%) 10 (10%) 

Inflammation, chronic 1 (1%) 2 (2%) 1 (1%) 1 (1%) 

Transitional epithelium, hyperplasia 2 (2%) 1 (1%) 
100 60-Hz Magnetic Fields, NTP TR 488 

 


 


 


 

101 

APPENDIX C
 

SUMMARY OF LESIONS IN MALE MICE
 

IN THE 2-YEAR WHOLE-BODY EXPOSURE STUDY
 

OF 60-HZ MAGNETIC FIELDS
 

TABLE C1 Summary of the Incidence of Neoplasms in Male Mice 

in the 2-Year Whole-Body Exposure Study of 60-Hz Magnetic Fields .............. 102 

TABLE C2 Statistical Analysis of Primary Neoplasms in Male Mice 

in the 2-Year Whole-Body Exposure Study of 60-Hz Magnetic Fields .............. 108 

TABLE C3 Summary of the Incidence of Nonneoplastic Lesions in Male Mice 

in the 2-Year Whole-Body Exposure Study of 60-Hz Magnetic Fields .............. 111 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

102 60-Hz Magnetic Fields, NTP TR 488 

TABLE C1 

Summary of the Incidence of Neoplasms in Male Mice in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fieldsa 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Disposition Summary 

Animals initially in study 100 100 100 100 100 

Early deaths 

Moribund 11 13 6 15 8 

Natural deaths 13 15 10 23 18 

Survivors 

Died last week of study 1 

Terminal sacrifice 76 72 84 62 73 

Animals examined microscopically 100 100 100 100 100 

Alimentary System 

Esophagus (97) (97) (98) (96) (99) 

Periesophageal tissue, sarcoma,

 metastatic, uncertain primary site 1 (1%) 

Gallbladder (84) (83) (84) (75) (82) 

Adenoma 1 (1%) 

Carcinoma, metastatic, intestine small,

 duodenum 1 (1%) 

Intestine large, colon (93) (94) (92) (83) (85) 

Intestine large, rectum (93) (90) (93) (81) (87) 

Intestine large, cecum (90) (89) (92) (81) (85) 

Intestine small, duodenum (89) (88) (92) (79) (84) 

Carcinoma 2 (2%) 1 (1%) 1 (1%) 

Polyp adenomatous 2 (2%) 1 (1%) 

Intestine small, jejunum (89) (94) (93) (80) (85) 

Carcinoma 1 (1%) 1 (1%) 3 (3%) 1 (1%) 

Intestine small, ileum (91) (89) (92) (81) (84) 

Carcinoma 1 (1%) 

Liver (100) (100) (100) (98) (99) 

Carcinoma, metastatic, islets, pancreatic 1 (1%) 

Carcinoma, metastatic, pancreas 1 (1%) 

Carcinoma, metastatic, intestine small,

 duodenum 1 (1%) 

Hemangiosarcoma 4 (4%) 2 (2%) 3 (3%) 5 (5%) 4 (4%) 

Hemangiosarcoma, metastatic, skin 1 (1%) 

Hemangiosarcoma, metastatic, spleen 1 (1%) 1 (1%) 

Hepatoblastoma 2 (2%) 2 (2%) 1 (1%) 4 (4%) 5 (5%) 

Hepatocellular carcinoma 19 (19%) 14 (14%) 20 (20%) 15 (15%) 23 (23%) 

Hepatocellular adenoma 28 (28%) 26 (26%) 32 (32%) 21 (21%) 30 (30%) 

Hepatocellular adenoma, multiple 2 (2%) 2 (2%) 

Hepatocholangiocarcinoma 1 (1%) 

Histiocytic sarcoma 1 (1%) 1 (1%) 1 (1%) 1 (1%) 

Rhabdomyosarcoma, metastatic, heart 1 (1%) 

Mesentery (13) (16) (8) (10) (9) 

Carcinoma, metastatic, islets, pancreatic 1 (13%) 

Carcinoma, metastatic, intestine small,

 duodenum 1 (6%) 

Hemangiosarcoma 1 (6%) 1 (13%) 

Hepatocellular carcinoma, metastatic, liver 1 (11%) 

Rhabdomyosarcoma, metastatic, heart 1 (13%) 

Rhabdomyosarcoma, metastatic, skeletal muscle 1 (10%) 

Sarcoma, metastatic, uncertain primary site 1 (10%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

60-Hz Magnetic Fields, NTP TR 488 103 

TABLE C1 

Summary of the Incidence of Neoplasms in Male Mice in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Alimentary System (continued) 

Oral mucosa (2) 

Squamous cell carcinoma 1 (50%) 

Pancreas (99) (99) (98) (95) (98) 

Carcinoma 1 (1%) 

Carcinoma, metastatic, islets, pancreatic 1 (1%) 

Carcinoma, metastatic, intestine small,

 duodenum 1 (1%) 

Rhabdomyosarcoma, metastatic,

 skeletal muscle 1 (1%) 

Sarcoma 1 (1%) 

Schwannoma malignant, metastatic, skin 1 (1%) 

Salivary glands (99) (99) (98) (96) (99) 

Stomach, forestomach (99) (98) (97) (96) (99) 

Sarcoma 1 (1%) 

Squamous cell carcinoma 1 (1%) 

Squamous cell papilloma 1 (1%) 

Stomach, glandular (94) (93) (97) (87) (93) 

Serosa, hemangiosarcoma, metastatic,

 mesentery 1 (1%) 

Tongue (1) 

Squamous cell papilloma 1 (100%) 

Cardiovascular System 

Blood vessel (97) (94) (100) (96) (98) 

Aorta, adventitia, rhabdomyosarcoma,

 metastatic, heart 1 (1%) 

Aorta, adventitia, sarcoma, metastatic,

 uncertain primary site 1 (1%) 

Heart (100) (100) (100) (99) (100) 

Carcinoma, metastatic, kidney 1 (1%) 

Hemangiosarcoma 2 (2%) 

Hemangiosarcoma, metastatic, liver 1 (1%) 2 (2%) 2 (2%) 

Hemangiosarcoma, metastatic, spleen 1 (1%) 1 (1%) 1 (1%) 

Rhabdomyosarcoma 1 (1%) 1 (1%) 

Sarcoma, metastatic, uncertain primary site 1 (1%) 

Endocrine System 

Adrenal cortex (99) (96) (99) (94) (97) 

Adenoma 3 (3%) 1 (1%) 5 (5%) 

Bilateral, rhabdomyosarcoma, metastatic,

 skeletal muscle 1 (1%) 

Capsule, carcinoma, metastatic, intestine

 small, duodenum 1 (1%) 

Adrenal medulla (98) (93) (99) (91) (96) 

Pheochromocytoma malignant 2 (2%) 

Pheochromocytoma benign 1 (1%) 1 (1%) 

Bilateral, rhabdomyosarcoma, metastatic,

 skeletal muscle 1 (1%) 

Islets, pancreatic (99) (99) (98) (97) (98) 

Adenoma 1 (1%) 3 (3%) 1 (1%) 1 (1%) 

Carcinoma 2 (2%) 1 (1%) 1 (1%) 

Hemangiosarcoma, metastatic, mesentery 1 (1%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

104 60-Hz Magnetic Fields, NTP TR 488 

TABLE C1 

Summary of the Incidence of Neoplasms in Male Mice in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Endocrine System (continued) 

Pineal gland (55) (58) (62) (45) (57) 

Pituitary gland (83) (84) (82) (84) (86) 

Pars distalis, adenoma 1 (1%) 1 (1%) 

Pars intermedia, adenoma 1 (1%) 

Thyroid gland (99) (98) (98) (97) (98) 

Adenoma 1 (1%) 1 (1%) 1 (1%) 

General Body System 

Tissue NOS (2) (4) (1) (1) 

Alveolar/bronchiolar carcinoma, metastatic,

 lung 1 (50%) 

Histiocytic sarcoma 1 (25%) 

Schwannoma malignant 1 (100%) 

Pelvic, sarcoma 1 (25%) 

Thoracic, fat, hemangioma 1 (100%) 

Genital System 

Epididymis (98) (99) (99) (96) (98) 

Carcinoma, metastatic, islets, pancreatic 1 (1%) 

Hemangiosarcoma, metastatic, skin 1 (1%) 

Histiocytic sarcoma 1 (1%) 

Bilateral, carcinoma, metastatic, intestine

 small, duodenum 1 (1%) 

Bilateral, sarcoma, metastatic, pancreas 1 (1%) 

Preputial gland (98) (98) (100) (95) (99) 

Prostate (98) (92) (94) (94) (92) 

Adenoma 1 (1%) 

Histiocytic sarcoma 1 (1%) 

Sarcoma, metastatic, pancreas 1 (1%) 

Seminal vesicle (99) (97) (98) (98) (98) 

Carcinoma 1 (1%) 

Carcinoma, metastatic, islets, pancreatic 1 (1%) 

Hemangiosarcoma, metastatic, mesentery 1 (1%) 

Bilateral, sarcoma, metastatic, pancreas 1 (1%) 

Testes (99) (98) (100) (96) (98) 

Adenoma 1 (1%) 1 (1%) 2 (2%) 1 (1%) 1 (1%) 

Hemangiosarcoma 1 (1%) 

Hematopoietic System 

Bone marrow (99) (99) (99) (99) (100) 

Hemangiosarcoma, metastatic, liver 2 (2%) 

Hemangiosarcoma, metastatic, skin 1 (1%) 

Hemangiosarcoma, metastatic, spleen 1 (1%) 1 (1%) 1 (1%) 

Mast cell tumor benign 1 (1%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

60-Hz Magnetic Fields, NTP TR 488 105 

TABLE C1 

Summary of the Incidence of Neoplasms in Male Mice in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Hematopoietic System (continued) 

Lymph node (6) (6) (5) (3) (7) 

Alveolar/bronchiolar carcinoma, metastatic,

 lung 1 (14%) 

Hemangiosarcoma 1 (14%) 

Hepatocellular carcinoma, metastatic, liver 1 (14%) 

Histiocytic sarcoma 1 (17%) 

Plasma cell tumor malignant 1 (17%) 

Bronchial, alveolar/bronchiolar carcinoma,

 metastatic, lung 1 (20%) 

Lumbar, hemangiosarcoma, metastatic,

 mesentery 1 (17%) 

Lumbar, histiocytic sarcoma 1 (33%) 

Lymph node, mandibular (92) (92) (92) (89) (90) 

Histiocytic sarcoma 1 (1%) 

Lymph node, mesenteric (87) (90) (96) (85) (92) 

Carcinoma, metastatic, islets, pancreatic 1 (1%) 

Carcinoma, metastatic, intestine small,

 duodenum 1 (1%) 

Histiocytic sarcoma 1 (1%) 1 (1%) 

Plasma cell tumor malignant 1 (1%) 

Rhabdomyosarcoma, metastatic, heart 1 (1%) 1 (1%) 

Sarcoma, metastatic, pancreas 1 (1%) 

Sarcoma, metastatic, uncertain primary site 1 (1%) 

Spleen (99) (98) (98) (93) (98) 

Hemangiosarcoma 2 (2%) 5 (5%) 3 (3%) 1 (1%) 

Hemangiosarcoma, metastatic, skin 1 (1%) 

Histiocytic sarcoma 1 (1%) 1 (1%) 

Thymus (69) (68) (63) (68) (60)

 Sarcoma, metastatic, uncertain primary site 1 (1%) 

Integumentary System 

Skin (99) (99) (100) (100) (100) 

Carcinoma, metastatic, harderian gland 1 (1%) 

Hemangiosarcoma 1 (1%) 

Histiocytic sarcoma 1 (1%) 

Rhabdomyosarcoma, metastatic, heart 1 (1%) 

Sarcoma 1 (1%) 

Schwannoma benign 1 (1%) 

Schwannoma malignant 1 (1%) 1 (1%) 

Squamous cell papilloma 1 (1%) 1 (1%) 

Musculoskeletal System 

Bone (97) (100) (99) (99) (99) 

Femur, hemangiosarcoma, metastatic, liver 1 (1%) 

Femur, hemangiosarcoma, metastatic, spleen 1 (1%) 

Skeletal muscle (8) (7) (2) (7) (4) 

Hemangiosarcoma, metastatic, mesentery 1 (14%) 

Rhabdomyosarcoma 1 (14%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

106 60-Hz Magnetic Fields, NTP TR 488 

TABLE C1 

Summary of the Incidence of Neoplasms in Male Mice in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Nervous System 

Brain (100) (99) (100) (99) (100) 

Meninges, sarcoma 1 (1%) 

Respiratory System 

Lung (100) (99) (100) (99) (99) 

Alveolar/bronchiolar adenoma 24 (24%) 11 (11%) 7 (7%) 14 (14%) 13 (13%) 

Alveolar/bronchiolar adenoma, multiple 2 (2%) 2 (2%) 2 (2%) 3 (3%) 

Alveolar/bronchiolar carcinoma 8 (8%) 11 (11%) 12 (12%) 10 (10%) 9 (9%) 

Alveolar/bronchiolar carcinoma, multiple 1 (1%) 

Carcinoma, metastatic, harderian gland 1 (1%) 

Carcinoma, metastatic, islets, pancreatic 1 (1%) 

Carcinoma, metastatic, kidney 1 (1%) 

Carcinoma, metastatic, pancreas 1 (1%) 

Hemangiosarcoma, metastatic, liver 1 (1%) 

Hemangiosarcoma, metastatic, mesentery 1 (1%) 

Hepatoblastoma, metastatic, liver 1 (1%) 

Hepatocellular carcinoma, metastatic, liver 2 (2%) 5 (5%) 8 (8%) 5 (5%) 9 (9%) 

Histiocytic sarcoma 1 (1%) 1 (1%) 

Pheochromocytoma malignant, metastatic,

 adrenal medulla 1 (1%) 

Rhabdomyosarcoma, metastatic, heart 1 (1%) 1 (1%) 

Sarcoma, metastatic, uncertain primary site 1 (1%) 1 (1%) 

Schwannoma malignant, metastatic, skin 1 (1%) 

Arteriole, hepatoblastoma, metastatic, liver 1 (1%) 

Nose (99) (99) (100) (97) (100) 

Sinus, sarcoma, metastatic, eye 1 (1%) 

Special Senses System 

Eye (2) (2) (1) 

Retrobulbar, sarcoma 1 (50%) 

Harderian gland (99) (99) (100) (96) (99) 

Adenoma 12 (12%) 14 (14%) 16 (16%) 10 (10%) 11 (11%) 

Carcinoma 1 (1%) 3 (3%) 

Sarcoma, metastatic, eye 1 (1%) 

Bilateral, adenoma 2 (2%) 2 (2%) 

Bilateral, carcinoma 1 (1%) 

Urinary System 

Kidney (99) (98) (99) (96) (97) 

Sarcoma, metastatic, pancreas 1 (1%) 

Bilateral, carcinoma 1 (1%) 

Bilateral, rhabdomyosarcoma, metastatic,

 heart 1 (1%) 

Capsule, rhabdomyosarcoma, metastatic, heart 1 (1%) 

Cortex, rhabdomyosarcoma, metastatic, heart 1 (1%) 

Renal tubule, adenoma 1 (1%) 2 (2%) 

Urinary bladder (98) (95) (95) (93) (94) 

Histiocytic sarcoma 1 (1%) 

Papilloma 1 (1%) 

Sarcoma, metastatic, pancreas 1 (1%) 
 

 

107 

c 

60-Hz Magnetic Fields, NTP TR 488 

TABLE C1 

Summary of the Incidence of Neoplasms in Male Mice in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Systemic Lesions 

Multiple organsb (100) (100) (100) (100) (100) 

Histiocytic sarcoma 1 (1%) 1 (1%) 3 (3%) 1 (1%) 1 (1%) 

Leukemia granulocytic 1 (1%) 

Lymphoma malignant 8 (8%) 7 (7%) 4 (4%) 7 (7%) 6 (6%) 

Mesothelioma malignant 2 (2%) 1 (1%) 

Neoplasm Summary 

Total animals with primary neoplasmsc 71 81 72 74 76 

Total primary neoplasms 127 123 122 112 124 

Total animals with benign neoplasms 54 50 54 47 52 

Total benign neoplasms 77 64 68 57 65 

Total animals with malignant neoplasms 40 49 45 49 48 

Total malignant neoplasms 50 59 54 55 59 

Total animals with metastatic neoplasms 8 11 15 17 13 

Total metastatic neoplasms 9 23 28 36 22 

Total animals with malignant neoplasms

 of uncertain primary site 1 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 

Primary neoplasms: all neoplasms except metastatic neoplasms 
108 60-Hz Magnetic Fields, NTP TR 488 

TABLE C2 

Statistical Analysis of Primary Neoplasms in Male Mice in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Adrenal Cortex: Adenoma 

Overall ratea 

Adjusted rateb 3/99 (3%) 

3.3% 

0/96 (0%) 

0.0% 

1/99 (1%) 

1.1% 

5/94 (5%) 

6.1% 

0/97 (0%) 

0.0% 

Terminal ratec 3/76 (4%) 0/71 (0%) 1/84 (1%) 5/61 (8%) 0/73 (0%) 

First incidence (days) 

Poly-3 testd 734 (T) 

P=0.032 

—e 

P=0.134N 

734 (T) 

P=0.305N 

734 (T) 

P=0.297 

— 

P=0.133N 

Harderian Gland: Adenoma 

Overall rate 12/100 (12%) 16/100 (16%) 16/100 (16%) 12/100 (12%) 11/100 (11%) 

Adjusted rate 13.0% 17.8% 16.9% 13.9% 12.0% 

Terminal rate 11/76 (15%) 12/72 (17%) 11/84 (13%) 9/62 (15%) 8/74 (11%) 

First incidence (days) 716 589 585 483 533 

Poly-3 test P=0.413N P=0.240 P=0.290 P=0.517 P=0.511N 

Harderian Gland: Adenoma or Carcinoma 

Overall rate 12/100 (12%) 18/100 (18%) 16/100 (16%) 12/100 (12%) 14/100 (14%) 

Adjusted rate 13.0% 19.9% 16.9% 13.9% 15.3% 

Terminal rate 11/76 (15%) 13/72 (18%) 11/84 (13%) 9/62 (15%) 11/74 (15%) 

First incidence (days) 716 485 585 483 533 

Poly-3 test P=0.342N P=0.142 P=0.290 P=0.517 P=0.405 

Liver: Hemangiosarcoma 

Overall rate 4/100 (4%) 2/100 (2%) 3/100 (3%) 5/98 (5%) 4/99 (4%) 

Adjusted rate 4.3% 2.2% 3.2% 5.9% 4.5% 

Terminal rate 1/76 (1%) 1/72 (1%) 1/84 (1%) 3/62 (5%) 3/74 (4%) 

First incidence (days) 582 624 585 518 666 

Poly-3 test P=0.222 P=0.361N P=0.498N P=0.446 P=0.622 

Liver: Hepatocellular Adenoma 

Overall rate 30/100 (30%) 26/100 (26%) 32/100 (32%) 21/98 (21%) 32/99 (32%) 

Adjusted rate 32.3% 28.9% 34.0% 24.4% 35.3% 

Terminal rate 28/76 (37%) 22/72 (31%) 30/84 (36%) 15/62 (24%) 29/74 (39%) 

First incidence (days) 646 560 562 500 415 

Poly-3 test P=0.148N P=0.367N P=0.460 P=0.156N P=0.391 

Liver: Hepatocellular Carcinoma 

Overall rate 19/100 (19%) 14/100 (14%) 20/100 (20%) 15/98 (15%) 23/99 (23%) 

Adjusted rate 19.8% 15.3% 21.2% 17.1% 24.4% 

Terminal rate 8/76 (11%) 6/72 (8%) 17/84 (20%) 9/62 (15%) 9/74 (12%) 

First incidence (days) 520 542 527 480 456 

Poly-3 test P=0.472N P=0.268N P=0.477 P=0.392N P=0.279 

Liver: Hepatocellular Adenoma or Carcinoma 

Overall rate 46/100 (46%) 37/100 (37%) 45/100 (45%) 35/98 (36%) 52/99 (53%) 

Adjusted rate 47.8% 39.9% 47.2% 39.5% 54.5% 

Terminal rate 34/76 (45%) 26/72 (36%) 40/84 (48%) 24/62 (39%) 36/74 (49%) 

First incidence (days) 520 542 527 480 415 

Poly-3 test P=0.242N P=0.169N P=0.522N P=0.157N P=0.215 

 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 


 

60-Hz Magnetic Fields, NTP TR 488 109 

TABLE C2 

Statistical Analysis of Primary Neoplasms in Male Mice in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Liver: Hepatoblastoma 

Overall rate 2/100 (2%) 2/100 (2%) 1/100 (1%) 4/98 (4%) 5/99 (5%) 

Adjusted rate 2.2% 2.3% 1.1% 4.7% 5.5% 

Terminal rate 1/76 (1%) 2/72 (3%) 1/84 (1%) 3/62 (5%) 2/74 (3%) 

First incidence (days) 731 734 (T) 734 (T) 716 666 

Poly-3 test P=0.160 P=0.678 P=0.498N P=0.300 P=0.212 

Liver: Hepatocellular Carcinoma or Hepatoblastoma 

Overall rate 21/100 (21%) 16/100 (16%) 21/100 (21%) 19/98 (19%) 27/99 (27%)
 

Adjusted rate 21.9% 17.5% 22.2% 21.7% 28.5%
 

Terminal rate 9/76 (12%) 8/72 (11%) 18/84 (21%) 12/62 (19%) 11/74 (15%)
 

First incidence (days) 520 542 527 480 456
 

Poly-3 test P=0.428 P=0.283N P=0.545 P=0.557N P=0.189
 

Liver: Hepatocellular Adenoma, Hepatocellular Carcinoma, or Hepatoblastoma 

Overall rate 47/100 (47%) 38/100 (38%) 46/100 (46%) 38/98 (39%) 55/99 (53%)
 

Adjusted rate 48.8% 41.0% 48.2% 42.8% 57.4%
 

Terminal rate 34/76 (45%) 27/72 (38%) 41/84 (49%) 26/62 (42%) 37/74 (50%)
 

First incidence (days) 520 542 527 480 415
 

Poly-3 test P=0.371N P=0.171N P=0.522N P=0.247N P=0.147
 

Lung: Alveolar/bronchiolar Adenoma 

Overall rate 26/100 (26%) 11/99 (11%) 9/100 (9%) 16/99 (16%) 16/99 (16%)
 

Adjusted rate 28.0% 12.5% 9.6% 18.0% 17.9%
 

Terminal rate 22/76 (29%) 10/72 (14%) 7/84 (8%) 7/62 (11%) 15/74 (20%)
 

First incidence (days) 683 722 585 518 672
 

Poly-3 test P=0.470N P=0.007N P<0.001N P=0.077N P=0.073N
 

Lung: Alveolar/bronchiolar Carcinoma 

Overall rate 8/100 (8%) 11/99 (11%) 12/100 (12%) 10/99 (10%) 10/99 (10%)
 

Adjusted rate 8.6% 12.4% 12.8% 11.5% 11.2%
 

Terminal rate 7/76 (9%) 9/72 (13%) 11/84 (13%) 5/62 (8%) 9/74 (12%)
 

First incidence (days) 715 612 430 448 668
 

Poly-3 test P=0.495 P=0.280 P=0.249 P=0.351 P=0.377 

Lung: Alveolar/bronchiolar Adenoma or Carcinoma 

Overall rate 30/100 (30%) 21/99 (21%) 19/100 (19%) 25/99 (25%) 23/99 (23%)
 

Adjusted rate 32.2% 23.7% 20.1% 27.7% 25.6%
 

Terminal rate 25/76 (33%) 19/72 (26%) 16/84 (19%) 11/62 (18%) 21/74 (28%)
 

First incidence (days) 683 612 430 448 668
 

Poly-3 test P=0.495 P=0.130N P=0.041N P=0.302N P=0.203N
 

Spleen: Hemangiosarcoma 

Overall rate 2/99 (2%) 5/98 (5%) 0/98 (0%) 3/93 (3%) 1/98 (1%) 

Adjusted rate 2.2% 5.6% 0.0% 3.7% 1.1% 

Terminal rate 2/76 (3%) 3/72 (4%) 0/84 (0%) 2/62 (3%) 1/74 (1%) 

First incidence (days) 734 (T) 400 — 726 735 (T) 

Poly-3 test P=0.567 P=0.208 P=0.238N P=0.445 P=0.513N 
	 

	 

110 60-Hz Magnetic Fields, NTP TR 488 

TABLE C2 

Statistical Analysis of Primary Neoplasms in Male Mice in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

All Organs: Hemangiosarcoma 

Overall rate 6/100 (6%) 10/100 (10%) 6/100 (6%) 8/100 (8%) 5/100 (5%) 

Adjusted rate 6.4% 11.0% 6.4% 9.2% 5.5% 

Terminal rate 3/76 (4%) 6/72 (8%) 3/84 (4%) 5/62 (8%) 4/74 (5%) 

First incidence (days) 582 400 585 518 666 

Poly-3 test P=0.473 P=0.199 P=0.611N P=0.335 P=0.524N 

All Organs: Hemangioma or Hemangiosarcoma 

Overall rate 6/100 (6%) 10/100 (10%) 7/100 (7%) 8/100 (8%) 5/100 (5%) 

Adjusted rate 6.4% 11.0% 7.4% 9.2% 5.5% 

Terminal rate 3/76 (4%) 6/72 (8%) 4/84 (5%) 5/62 (8%) 4/74 (5%) 

First incidence (days) 582 400 585 518 666 

Poly-3 test P=0.488 P=0.199 P=0.506 P=0.335 P=0.524N 

All Organs: Malignant Lymphoma 

Overall rate 8/100 (8%) 7/100 (7%) 4/100 (4%) 7/100 (7%) 6/100 (6%) 

Adjusted rate 8.6% 7.8% 4.3% 8.0% 6.6% 

Terminal rate 7/76 (9%) 4/72 (6%) 3/84 (4%) 3/62 (5%) 3/74 (4%) 

First incidence (days) 691 562 701 510 579 

Poly-3 test P=0.536 P=0.522N P=0.182N P=0.550N P=0.402N 

All Organs: Benign Neoplasms 

Overall rate 54/100 (54%) 50/100 (50%) 54/100 (54%) 47/100 (47%) 52/100 (52%) 

Adjusted rate 57.7% 54.8% 56.5% 51.3% 55.9% 

Terminal rate 47/76 (62%) 42/72 (58%) 46/84 (55%) 30/62 (48%) 44/74 (60%) 

First incidence (days) 646 542 562 483 415 

Poly-3 test P=0.234N P=0.402N P=0.490N P=0.230N P=0.458N 

All Organs: Malignant Neoplasms 

Overall rate 40/100 (40%) 49/100 (49%) 45/100 (45%) 49/100 (49%) 48/100 (48%) 

Adjusted rate 41.3% 50.3% 46.1% 51.4% 49.7% 

Terminal rate 25/76 (33%) 27/72 (38%) 35/84 (42%) 23/62 (37%) 29/74 (39%) 

First incidence (days) 520 400 430 448 456 

Poly-3 test P=0.205 P=0.134 P=0.302 P=0.103 P=0.153 

All Organs: Benign or Malignant Neoplasms 

Overall rate 71/100 (71%) 81/100 (81%) 72/100 (72%) 74/100 (74%) 76/100 (76%) 

Adjusted rate 73.0% 82.2% 73.3% 76.5% 77.9% 

Terminal rate 53/76 (70%) 56/72 (78%) 60/84 (71%) 43/62 (69%) 54/74 (73%) 

First incidence (days) 520 400 430 448 415 

Poly-3 test P=0.506N P=0.081 P=0.547 P=0.343 P=0.266 

(T)Terminal sacrifice 

a Number of neoplasm-bearing animals/number of animals examined. Denominator is number of animals examined microscopically for adrenal gland, liver, 

lung, and spleen; for other tissues, denominator is number of animals necropsied. b	 Poly-3 estimated neoplasm incidence after adjustment for intercurrent mortality 

Observed incidence at terminal kill 

d	 Beneath the control incidence are the P values associated with the trend test; the trend does not include the 10 G intermittent group. 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 negative trend or a lower incidence in an exposure group is indicated by N. e Not applicable; no neoplasms in animal group 

c 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

60-Hz Magnetic Fields, NTP TR 488 111 

TABLE C3 

Summary of the Incidence of Nonneoplastic Lesions in Male Mice in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fieldsa 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Disposition Summary 

Animals initially in study 100 100 100 100 100 

Early deaths 

Moribund 11 13 6 15 8 

Natural deaths 13 15 10 23 18 

Survivors 

Died last week of study 1 

Terminal sacrifice 76 72 84 62 73 

Animals examined microscopically 100 100 100 100 100 

Alimentary System 

Gallbladder (84) (83) (84) (75) (82) 

Congestion 1 (1%) 

Inflammation, granulomatous 1 (1%) 

Epithelium, cyst 4 (5%) 2 (2%) 2 (3%) 2 (2%) 

Epithelium, hyperplasia, focal 1 (1%) 

Intestine large, colon (93) (94) (92) (83) (85) 

Lymphoid tissue, hyperplasia 1 (1%) 

Muscularis, hypertrophy 1 (1%) 

Intestine large, rectum (93) (90) (93) (81) (87) 

Lymphoid tissue, hyperplasia 1 (1%) 

Intestine large, cecum (90) (89) (92) (81) (85) 

Inflammation 1 (1%) 1 (1%) 

Lymphoid tissue, hyperplasia 41 (46%) 33 (37%) 37 (40%) 20 (25%) 46 (54%) 

Serosa, fibrosis 1 (1%) 

Intestine small, duodenum (89) (88) (92) (79) (84) 

Infiltration cellular, histiocyte 1 (1%) 

Muscularis, inflammation 1 (1%) 

Peyer’s patch, hyperplasia 2 (2%) 1 (1%) 

Intestine small, jejunum (89) (94) (93) (80) (85) 

Inflammation 1 (1%) 1 (1%) 

Epithelium, hyperplasia, focal 1 (1%) 

Muscularis, hypertrophy 3 (3%) 1 (1%) 2 (2%) 

Peyer’s patch, hyperplasia 1 (1%) 5 (5%) 1 (1%) 1 (1%) 

Serosa, inflammation 1 (1%) 

Intestine small, ileum (91) (89) (92) (81) (84) 

Inflammation 1 (1%) 

Epithelium, degeneration 1 (1%) 

Muscularis, hypertrophy 9 (10%) 8 (9%) 7 (8%) 

Peyer’s patch, hyperplasia 1 (1%) 1 (1%) 

Serosa, inflammation 1 (1%) 

a Number of animals examined microscopically at the site and the number of animals with lesion 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

112 60-Hz Magnetic Fields, NTP TR 488 

TABLE C3 

Summary of the Incidence of Nonneoplastic Lesions in Male Mice in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Alimentary System (continued) 

Liver (100) (100) (100) (98) (99) 

Basophilic focus 2 (2%) 2 (2%) 

Clear cell focus 7 (7%) 9 (9%) 9 (9%) 7 (7%) 9 (9%) 

Clear cell focus, multiple 7 (7%) 9 (9%) 6 (6%) 4 (4%) 5 (5%) 

Congestion 1 (1%) 

Eosinophilic focus 10 (10%) 12 (12%) 11 (11%) 14 (14%) 15 (15%) 

Eosinophilic focus, multiple 2 (2%) 1 (1%) 4 (4%) 1 (1%) 1 (1%) 

Hematopoietic cell proliferation 1 (1%) 

Hepatodiaphragmatic nodule 2 (2%) 

Infiltration cellular, focal, mixed cell 6 (6%) 10 (10%) 14 (14%) 10 (10%) 11 (11%) 

Inflammation, focal 1 (1%) 

Inflammation, granulomatous 1 (1%) 

Metaplasia, focal, osseous 1 (1%) 

Mixed cell focus 4 (4%) 1 (1%) 3 (3%) 4 (4%) 3 (3%) 

Necrosis 7 (7%) 6 (6%) 4 (4%) 4 (4%) 3 (3%) 

Pigmentation 1 (1%) 

Thrombosis, focal 1 (1%) 

Bile duct, cyst 2 (2%) 1 (1%) 

Hepatocyte, vacuolization cytoplasmic 13 (13%) 9 (9%) 6 (6%) 6 (6%) 5 (5%) 

Hepatocyte, centrilobular, hypertrophy 1 (1%) 

Sinusoid, centrilobular, dilatation 1 (1%) 

Mesentery (13) (16) (8) (10) (9) 

Infiltration cellular, histiocyte 1 (8%) 

Inflammation 1 (6%) 1 (10%) 

Artery, inflammation 1 (8%) 1 (6%) 1 (13%) 

Fat, inflammation 1 (8%) 3 (19%) 2 (25%) 

Fat, necrosis 11 (85%) 11 (69%) 4 (50%) 6 (60%) 7 (78%) 

Pancreas (99) (99) (98) (95) (98) 

Cytoplasmic alteration 1 (1%) 

Infiltration cellular, focal, mixed cell 1 (1%) 1 (1%) 1 (1%) 

Infiltration cellular, lymphocyte 1 (1%) 4 (4%) 2 (2%) 5 (5%) 

Inflammation 1 (1%) 

Lipomatosis 1 (1%) 11 (11%) 14 (14%) 1 (1%) 4 (4%) 

Necrosis 1 (1%) 

Vacuolization cytoplasmic 16 (16%) 31 (31%) 28 (29%) 5 (5%) 28 (29%) 

Acinus, atrophy 1 (1%) 1 (1%) 2 (2%) 

Acinus, cytoplasmic alteration 1 (1%) 3 (3%) 4 (4%) 

Acinus, degeneration 1 (1%) 

Acinus, hypertrophy, focal 1 (1%) 1 (1%) 

Duct, cyst 2 (2%) 1 (1%) 1 (1%) 2 (2%) 

Salivary glands (99) (99) (98) (96) (99) 

Atrophy 1 (1%) 1 (1%) 1 (1%) 1 (1%) 1 (1%) 

Infiltration cellular, lymphocyte 66 (67%) 65 (66%) 72 (73%) 61 (64%) 69 (70%) 

Vacuolization cytoplasmic 1 (1%) 

Stomach, forestomach (99) (98) (97) (96) (99) 

Diverticulum 1 (1%) 

Inflammation, focal 1 (1%) 1 (1%) 

Epithelium, atrophy 9 (9%) 10 (10%) 8 (8%) 7 (7%) 8 (8%) 

Epithelium, hyperplasia 3 (3%) 1 (1%) 

Epithelium, hyperplasia, focal 1 (1%) 

Epithelium, vacuolization cytoplasmic 1 (1%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

60-Hz Magnetic Fields, NTP TR 488 113 

TABLE C3 

Summary of the Incidence of Nonneoplastic Lesions in Male Mice in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Alimentary System (continued) 

Stomach, glandular (94) (93) (97) (87) (93) 

Erosion, focal 1 (1%) 

Inflammation 3 (3%) 1 (1%) 1 (1%) 

Epithelium, atrophy 8 (9%) 9 (10%) 8 (8%) 8 (9%) 10 (11%) 

Epithelium, cyst, focal 6 (6%) 10 (11%) 10 (10%) 3 (3%) 11 (12%) 

Epithelium, hyperplasia, focal 1 (1%) 

Epithelium, mineralization 1 (1%) 1 (1%) 

Serosa, inflammation 1 (1%) 

Cardiovascular System 

Blood vessel (97) (94) (100) (96) (98) 

Aorta, mineralization 1 (1%) 1 (1%) 

Heart (100) (100) (100) (99) (100) 

Inflammation, focal 2 (2%) 1 (1%) 5 (5%) 2 (2%) 2 (2%) 

Arteriole, inflammation 1 (1%) 

Arteriole, mineralization 1 (1%) 

Artery, inflammation 1 (1%) 1 (1%) 

Artery, mineralization 1 (1%) 1 (1%) 

Atrium, infiltration cellular 1 (1%) 

Atrium, thrombosis 1 (1%) 

Capillary, myocardium, infiltration cellular,

 focal 1 (1%) 

Epicardium, mineralization 1 (1%) 1 (1%) 

Myocardium, degeneration 2 (2%) 2 (2%) 

Myocardium, mineralization 1 (1%) 

Myocardium, necrosis, focal 1 (1%) 

Valve, thrombosis 2 (2%) 

Endocrine System 

Adrenal cortex (99) (96) (99) (94) (97) 

Bilateral, mineralization 1 (1%) 

Bilateral, capsule, hyperplasia 55 (56%) 52 (54%) 53 (54%) 50 (53%) 52 (54%) 

Bilateral, capsule, mineralization 1 (1%) 1 (1%) 

Bilateral, zona fasciculata, hyperplasia,

 focal 1 (1%) 1 (1%) 

Bilateral, zona fasciculata, hypertrophy 1 (1%) 2 (2%) 2 (2%) 

Bilateral, zona fasciculata, hypertrophy,

 focal 2 (2%) 3 (3%) 6 (6%) 2 (2%) 3 (3%) 

Capsule, hyperplasia 31 (31%) 31 (32%) 38 (38%) 31 (33%) 33 (34%) 

Zona fasciculata, degeneration, focal 1 (1%) 

Zona fasciculata, hyperplasia, focal 3 (3%) 6 (6%) 7 (7%) 2 (2%) 5 (5%) 

Zona fasciculata, hypertrophy 8 (8%) 14 (15%) 11 (11%) 7 (7%) 5 (5%) 

Zona fasciculata, hypertrophy, focal 13 (13%) 17 (18%) 15 (15%) 10 (11%) 16 (16%) 

Zona fasciculata, infiltration cellular,

 polymorphonuclear 1 (1%) 

Zona fasciculata, vacuolization cytoplasmic 2 (2%) 

Zona fasciculata, vacuolization cytoplasmic,

 focal 1 (1%) 

Zona glomerulosa, hyperplasia, focal 3 (3%) 7 (7%) 4 (4%) 2 (2%) 7 (7%) 

Zona reticularis, degeneration, fatty 1 (1%) 1 (1%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

114 60-Hz Magnetic Fields, NTP TR 488 

TABLE C3 

Summary of the Incidence of Nonneoplastic Lesions in Male Mice in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Endocrine System (continued) 

Adrenal medulla (98) (93) (99) (91) (96) 

Angiectasis 1 (1%) 

Hyperplasia 2 (2%) 3 (3%) 3 (3%) 5 (5%) 

Islets, pancreatic (99) (99) (98) (97) (98) 

Hyperplasia 97 (98%) 88 (89%) 84 (86%) 84 (87%) 89 (91%) 

Hypertrophy, focal 1 (1%) 

Infiltration cellular, lymphocyte 1 (1%) 

Infiltration cellular, histiocyte 1 (1%) 1 (1%) 

Parathyroid gland (66) (55) (72) (65) (67) 

Cyst 1 (2%) 1 (1%) 1 (2%) 2 (3%) 

Hyperplasia 1 (2%) 2 (4%) 2 (3%) 1 (1%) 

Infiltration cellular, lymphocyte 1 (1%) 

Infiltration cellular, mixed cell 1 (2%) 

Pituitary gland (83) (84) (82) (84) (86) 

Pars distalis, cyst 9 (11%) 7 (8%) 6 (7%) 4 (5%) 14 (16%) 

Pars distalis, hyperplasia, focal 1 (1%) 2 (2%) 1 (1%) 3 (4%) 1 (1%) 

Pars nervosa, cyst 1 (1%) 

Thyroid gland (99) (98) (98) (97) (98) 

Bilateral, follicle, cyst 1 (1%) 

Follicle, cyst 5 (5%) 13 (13%) 7 (7%) 7 (7%) 9 (9%) 

General Body System 

Tissue NOS (2) (4) (1) (1) 

Inflammation, acute 1 (25%) 

Abdominal, fat, necrosis 1 (50%) 

Genital System 

Coagulating gland (2) (2) (1) 

Cyst 1 (50%) 1 (50%) 1 (100%) 

Bilateral, cyst 1 (50%) 

Epididymis (98) (99) (99) (96) (98) 

Cyst 1 (1%) 

Granuloma sperm 2 (2%) 2 (2%) 1 (1%) 2 (2%) 

Hyperplasia 1 (1%) 

Infiltration cellular, lymphocyte 13 (13%) 9 (9%) 16 (16%) 14 (15%) 15 (15%) 

Inflammation 2 (2%) 

Inflammation, granulomatous 1 (1%) 

Spermatocele 2 (2%) 3 (3%) 7 (7%) 6 (6%) 

Bilateral, atrophy 1 (1%) 

Bilateral, granuloma sperm 1 (1%) 1 (1%) 

Bilateral, infiltration cellular, lymphocyte 11 (11%) 2 (2%) 5 (5%) 4 (4%) 9 (9%) 

Preputial gland (98) (98) (100) (95) (99) 

Atrophy 8 (8%) 22 (22%) 15 (15%) 10 (11%) 18 (18%) 

Cyst 29 (30%) 13 (13%) 7 (7%) 23 (24%) 17 (17%) 

Infiltration cellular, lymphocyte 1 (1%) 1 (1%) 

Inflammation 15 (15%) 18 (18%) 33 (33%) 27 (28%) 34 (34%) 

Bilateral, atrophy 17 (17%) 34 (35%) 34 (34%) 27 (28%) 38 (38%) 

Bilateral, cyst 55 (56%) 75 (77%) 86 (86%) 53 (56%) 72 (73%) 

Bilateral, inflammation 31 (32%) 19 (19%) 23 (23%) 26 (27%) 27 (27%) 

Bilateral, mineralization 1 (1%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

60-Hz Magnetic Fields, NTP TR 488 115 

TABLE C3 

Summary of the Incidence of Nonneoplastic Lesions in Male Mice in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Genital System (continued) 

Prostate (98) (92) (94) (94) (92) 

Atrophy 1 (1%) 

Infiltration cellular, lymphocyte 2 (2%) 4 (4%) 4 (4%) 2 (2%) 6 (7%) 

Inflammation 1 (1%) 1 (1%) 

Epithelium, hyperplasia 49 (50%) 52 (57%) 56 (60%) 47 (50%) 45 (49%) 

Seminal vesicle (99) (97) (98) (98) (98) 

Atrophy 2 (2%) 1 (1%) 

Cyst 28 (28%) 22 (23%) 23 (23%) 19 (19%) 16 (16%) 

Infiltration cellular, lymphocyte 1 (1%) 

Inflammation 2 (2%) 2 (2%) 

Bilateral, atrophy 1 (1%) 1 (1%) 

Bilateral, cyst 52 (53%) 41 (42%) 36 (37%) 49 (50%) 42 (43%) 

Bilateral, inflammation 1 (1%) 

Testes (99) (98) (100) (96) (98) 

Atrophy 3 (3%) 3 (3%) 1 (1%) 2 (2%) 1 (1%) 

Hemorrhage, focal 1 (1%) 

Mineralization 1 (1%) 1 (1%) 1 (1%) 

Necrosis 1 (1%) 

Bilateral, atrophy 2 (2%) 6 (6%) 1 (1%) 

Interstitial cell, hyperplasia, focal 1 (1%) 

Tunic, inflammation 1 (1%) 

Tunic, mineralization 1 (1%) 1 (1%) 1 (1%) 

Tunic, mineralization, focal 1 (1%) 

Hematopoietic System 

Bone marrow (99) (99) (99) (99) (100) 

Atrophy 1 (1%) 1 (1%) 3 (3%) 

Fibrosis 1 (1%) 

Hyperplasia 33 (33%) 30 (30%) 28 (28%) 30 (30%) 25 (25%) 

Infiltration cellular, focal, lymphocyte 3 (3%) 1 (1%) 2 (2%) 2 (2%) 

Myelofibrosis 1 (1%) 2 (2%) 2 (2%) 

Necrosis 1 (1%) 

Thrombosis 1 (1%) 

Erythroid cell, atrophy 1 (1%) 

Myeloid cell, hyperplasia 2 (2%) 3 (3%) 5 (5%) 

Lymph node (6) (6) (5) (3) (7) 

Inflammation, focal 1 (17%) 

Inguinal, hemorrhage 1 (20%) 

Inguinal, hyperplasia 1 (20%) 

Inguinal, necrosis 1 (20%) 

Lumbar, hemorrhage 1 (17%) 

Lumbar, hyperplasia 1 (14%) 

Lumbar, infiltration cellular, plasma cell 1 (17%) 

Lymph node, mandibular (92) (92) (92) (89) (90) 

Atrophy 4 (4%) 2 (2%) 3 (3%) 4 (4%) 1 (1%) 

Hemorrhage 1 (1%) 1 (1%) 

Hyperplasia 1 (1%) 4 (4%) 1 (1%) 1 (1%) 3 (3%) 

Infiltration cellular, mast cell 1 (1%) 1 (1%) 7 (8%) 2 (2%) 

Infiltration cellular, plasma cell 2 (2%) 3 (3%) 2 (2%) 1 (1%) 

Infiltration cellular, polymorphonuclear 1 (1%) 

Infiltration cellular, histiocyte 1 (1%) 3 (3%) 

Infiltration cellular, mixed cell 4 (4%) 2 (2%) 3 (3%) 1 (1%) 

Necrosis 1 (1%) 

Pigmentation 2 (2%) 4 (4%) 3 (3%) 2 (2%) 4 (4%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

116 60-Hz Magnetic Fields, NTP TR 488 

TABLE C3 

Summary of the Incidence of Nonneoplastic Lesions in Male Mice in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Hematopoietic System (continued) 

Lymph node, mesenteric (87) (90) (96) (85) (92) 

Atrophy 6 (7%) 12 (13%) 14 (15%) 7 (8%) 12 (13%) 

Hematopoietic cell proliferation 1 (1%) 

Hemorrhage 3 (3%) 2 (2%) 3 (3%) 3 (4%) 5 (5%) 

Hyperplasia 7 (8%) 5 (5%) 1 (1%) 3 (3%) 

Infiltration cellular, plasma cell 1 (1%) 

Infiltration cellular, lymphocyte 1 (1%) 1 (1%) 

Infiltration cellular, histiocyte 59 (68%) 67 (74%) 79 (82%) 56 (66%) 72 (78%) 

Infiltration cellular, mixed cell 3 (3%) 5 (6%) 2 (2%) 3 (4%) 6 (7%) 

Necrosis 1 (1%) 

Pigmentation 1 (1%) 

Artery, inflammation 1 (1%) 

Spleen (99) (98) (98) (93) (98) 

Hematopoietic cell proliferation 37 (37%) 43 (44%) 52 (53%) 36 (39%) 48 (49%) 

Pigmentation 1 (1%) 1 (1%) 

Capsule, degeneration, focal 1 (1%) 

Lymphoid follicle, atrophy 11 (11%) 12 (12%) 8 (8%) 14 (15%) 8 (8%) 

Lymphoid follicle, hyperplasia 21 (21%) 27 (28%) 17 (17%) 13 (14%) 19 (19%) 

Red pulp, atrophy 4 (4%) 3 (3%) 4 (4%) 4 (4%) 

Red pulp, pigmentation 1 (1%) 

Thymus (69) (68) (63) (68) (60) 

Atrophy 62 (90%) 50 (74%) 47 (75%) 64 (94%) 44 (73%) 

Cyst, focal 4 (6%) 10 (15%) 9 (14%) 4 (6%) 5 (8%) 

Hemorrhage 1 (1%) 1 (2%) 

Hyperplasia, lymphoid 3 (4%) 5 (7%) 9 (14%) 5 (8%) 

Integumentary System 

Mammary gland (2) (1) (3) (4) (1) 

Hyperplasia 1 (33%) 

Duct, dilatation 1 (25%) 

Skin (99) (99) (100) (100) (100) 

Cyst 1 (1%) 1 (1%) 

Inflammation 1 (1%) 1 (1%) 1 (1%) 1 (1%) 

Ulcer, focal 1 (1%) 1 (1%) 1 (1%) 

Musculoskeletal System 

Bone (97) (100) (99) (99) (99) 

Cartilage, epiphysis, femur, cyst 1 (1%) 

Cartilage, epiphysis, femur, cyst, multiple 1 (1%) 

Femur, fibrous osteodystrophy 1 (1%) 

Vertebra, inflammation 1 (1%) 

Nervous System 

Brain (100) (99) (100) (99) (100) 

Hydrocephalus 1 (1%) 

Cerebellum, developmental malformation 1 (1%) 

Cerebellum, hemorrhage 1 (1%) 

Cerebrum, vacuolization cytoplasmic, focal 1 (1%) 

Thalamus, mineralization 70 (70%) 68 (69%) 60 (60%) 78 (79%) 63 (63%) 

Thalamus, vacuolization cytoplasmic, focal 1 (1%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

60-Hz Magnetic Fields, NTP TR 488 117 

TABLE C3 

Summary of the Incidence of Nonneoplastic Lesions in Male Mice in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Nervous System (continued) 

Peripheral nerve (7) (8) (2) (6) (3) 

Sciatic, degeneration 1 (13%) 

Respiratory System 

Lung (100) (99) (100) (99) (99) 

Congestion 1 (1%) 2 (2%) 

Infiltration cellular, lymphocyte 21 (21%) 16 (16%) 22 (22%) 24 (24%) 16 (16%) 

Inflammation, focal 3 (3%) 1 (1%) 3 (3%) 2 (2%) 

Mineralization, focal 1 (1%) 

Alveolar epithelium, hyperplasia, focal 2 (2%) 2 (2%) 3 (3%) 2 (2%) 

Alveolus, infiltration cellular, histiocyte 3 (3%) 5 (5%) 4 (4%) 3 (3%) 9 (9%) 

Arteriole, thrombosis 1 (1%) 1 (1%) 

Serosa, inflammation 1 (1%) 

Nose (99) (99) (100) (97) (100) 

Inflammation 1 (1%) 2 (2%) 3 (3%) 2 (2%) 7 (7%) 

Sinus, inflammation 1 (1%) 1 (1%) 

Special Senses System 

Eye (2) (2) (1) 

Atrophy 1 (50%) 

Cornea, inflammation 1 (50%) 

Harderian gland (99) (99) (100) (96) (99) 

Atrophy, focal 1 (1%) 1 (1%) 

Infiltration cellular, lymphocyte 8 (8%) 11 (11%) 10 (10%) 4 (4%) 9 (9%) 

Inflammation 1 (1%) 

Inflammation, focal 1 (1%) 1 (1%) 1 (1%) 

Necrosis, focal 1 (1%) 

Bilateral, infiltration cellular, lymphocyte 3 (3%) 2 (2%) 6 (6%) 5 (5%) 5 (5%) 

Epithelium, hypertrophy, focal 1 (1%) 

Urinary System 

Kidney (99) (98) (99) (96) (97) 

Hydronephrosis 1 (1%) 1 (1%) 

Infarct, focal 1 (1%) 3 (3%) 1 (1%) 1 (1%) 

Infiltration cellular, lymphocyte 1 (1%) 1 (1%) 

Arteriole, inflammation 1 (1%) 

Artery, inflammation 1 (1%) 

Bilateral, hydronephrosis 1 (1%) 2 (2%) 

Bilateral, infarct, focal 1 (1%) 

Bilateral, artery, inflammation 1 (1%) 1 (1%) 

Bilateral, capsule, mineralization 1 (1%) 

Bilateral, cortex, congestion 2 (2%) 2 (2%) 

Bilateral, cortex, cyst 4 (4%) 7 (7%) 6 (6%) 6 (6%) 2 (2%) 

Bilateral, cortex, infiltration cellular,

 lymphocyte 10 (10%) 8 (8%) 8 (8%) 10 (10%) 19 (20%) 

Bilateral, cortex, inflammation 1 (1%) 

Bilateral, cortex, mineralization 79 (80%) 78 (80%) 77 (78%) 66 (69%) 74 (76%) 

Bilateral, cortex, renal tubule, degeneration 72 (73%) 75 (77%) 76 (77%) 57 (59%) 71 (73%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

118 60-Hz Magnetic Fields, NTP TR 488 

TABLE C3 

Summary of the Incidence of Nonneoplastic Lesions in Male Mice in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Urinary System (continued) 

Kidney (continued) (99) (98) (99) (96) (97) 

Bilateral, cortex, renal tubule, dilatation 2 (2%) 1 (1%) 1 (1%) 5 (5%) 2 (2%) 

Bilateral, cortex, renal tubule, pigmentation 1 (1%) 2 (2%) 2 (2%) 1 (1%) 

Bilateral, medulla, infiltration cellular,

 lymphocyte 34 (34%) 26 (27%) 37 (37%) 26 (27%) 38 (39%) 

Bilateral, medulla, inflammation 1 (1%) 1 (1%) 

Bilateral, medulla, mineralization 1 (1%) 1 (1%) 

Bilateral, papilla, necrosis 1 (1%) 

Cortex, cyst 19 (19%) 23 (23%) 21 (21%) 11 (11%) 20 (21%) 

Cortex, degeneration, focal 1 (1%) 1 (1%) 

Cortex, infiltration cellular, focal, mixed cell 1 (1%) 

Cortex, infiltration cellular, lymphocyte 9 (9%) 10 (10%) 13 (13%) 6 (6%) 18 (19%) 

Cortex, inflammation 1 (1%) 2 (2%) 

Cortex, metaplasia, focal, osseous 4 (4%) 4 (4%) 8 (8%) 2 (2%) 4 (4%) 

Cortex, mineralization 1 (1%) 3 (3%) 

Cortex, renal tubule, degeneration 4 (4%) 2 (2%) 2 (2%) 1 (1%) 1 (1%) 

Cortex, renal tubule, dilatation 1 (1%) 2 (2%) 

Glomerulus, inflammation, focal 1 (1%) 

Medulla, infiltration cellular, lymphocyte 21 (21%) 14 (14%) 19 (19%) 15 (16%) 9 (9%) 

Medulla, inflammation 1 (1%) 1 (1%) 

Medulla, mineralization 1 (1%) 

Urethra (1) 

Cyst 1 (100%) 

Urinary bladder (98) (95) (95) (93) (94) 

Hemorrhage 1 (1%) 

Infiltration cellular, lymphocyte 4 (4%) 1 (1%) 1 (1%) 4 (4%) 

Inflammation 1 (1%) 1 (1%) 

Artery, inflammation 1 (1%) 

Transitional epithelium, hyperplasia 1 (1%) 

 


 


 


 

119 

APPENDIX D
 

SUMMARY OF LESIONS IN FEMALE MICE
 

THE 2-YEAR WHOLE-BODY EXPOSURE STUDY
 

OF 60-HZ MAGNETIC FIELDS
 

TABLE D1 Summary of the Incidence of Neoplasms in Female Mice 

in the 2-Year Whole-Body Exposure Study of 60-Hz Magnetic Fields .............. 120 

TABLE D2 Statistical Analysis of Primary Neoplasms in Female Mice 

in the 2-Year Whole-Body Exposure Study of 60-Hz Magnetic Fields .............. 126 

TABLE D3 Summary of the Incidence of Nonneoplastic Lesions in Female Mice 

in the 2-Year Whole-Body Exposure Study of 60-Hz Magnetic Fields .............. 129 
 

 

 

 

 

 

 

 

 

 

 

 

 

120 60-Hz Magnetic Fields, NTP TR 488 

TABLE D1 

Summary of the Incidence of Neoplasms in Female Mice in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fieldsa 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Disposition Summary 

Animals initially in study 100 100 100 100 100 

Early deaths 

Accidental deaths 1 1 2 1 

Moribund 6 7 6 7 8 

Natural deaths 23 18 13 18 15 

Survivors 

Died last week of study 1 

Terminal sacrifice 69 74 79 74 77 

Animals examined microscopically 100 100 100 100 100 

Alimentary System 

Esophagus (97) (100) (99) (98) (100) 

Gallbladder (70) (84) (87) (79) (91) 

Histiocytic sarcoma 1 (1%) 2 (2%) 

Rhabdomyosarcoma, metastatic, intestine

 small, jejunum 1 (1%) 

Intestine large, colon (82) (88) (90) (90) (93) 

Histiocytic sarcoma 1 (1%) 

Intestine large, cecum (78) (87) (90) (87) (92) 

Histiocytic sarcoma 1 (1%) 

Leiomyosarcoma 1 (1%) 

Serosa, histiocytic sarcoma 1 (1%) 

Intestine small, duodenum (77) (85) (90) (87) (91) 

Histiocytic sarcoma 1 (1%) 

Leiomyosarcoma 1 (1%) 

Polyp adenomatous 1 (1%) 1 (1%) 

Intestine small, jejunum (79) (86) (89) (91) (92) 

Histiocytic sarcoma 1 (1%) 

Sarcoma, metastatic, skin 1 (1%) 

Serosa, rhabdomyosarcoma, metastatic,

 skeletal muscle 1 (1%) 

Intestine small, ileum (78) (85) (90) (87) (93) 

Histiocytic sarcoma 1 (1%) 1 (1%) 

Liver (98) (97) (98) (99) (100) 

Hemangiosarcoma 1 (1%) 1 (1%) 1 (1%) 

Hemangiosarcoma, metastatic, spleen 1 (1%) 

Hepatocellular carcinoma 6 (6%) 5 (5%) 6 (6%) 6 (6%) 6 (6%) 

Hepatocellular carcinoma, multiple 1 (1%) 

Hepatocellular adenoma 15 (15%) 8 (8%) 19 (19%) 17 (17%) 11 (11%) 

Hepatocellular adenoma, multiple 2 (2%) 2 (2%) 1 (1%) 1 (1%) 2 (2%) 

Hepatocholangiocarcinoma 1 (1%) 

Histiocytic sarcoma 2 (2%) 2 (2%) 6 (6%) 

Plasma cell tumor malignant, metastatic,

 spleen 1 (1%) 

Plasma cell tumor malignant, metastatic,

 uncertain primary site 2 (2%) 1 (1%) 1 (1%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

60-Hz Magnetic Fields, NTP TR 488 121 

TABLE D1 

Summary of the Incidence of Neoplasms in Female Mice in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Alimentary System (continued) 

Mesentery (36) (27) (30) (30) (53) 

Histiocytic sarcoma 4 (8%) 

Leiomyosarcoma, metastatic, intestine small,

 duodenum 1 (3%) 

Liposarcoma 3 (11%) 1 (3%) 1 (2%) 

Osteosarcoma, metastatic, uncertain primary

 site 1 (2%) 

Plasma cell tumor malignant, metastatic,

 uncertain primary site 1 (2%) 

Rhabdomyosarcoma, metastatic,

 skeletal muscle 2 (6%) 

Sarcoma 1 (3%) 2 (7%) 1 (2%) 

Pancreas (87) (94) (96) (94) (95) 

Histiocytic sarcoma 3 (3%) 

Rhabdomyosarcoma, metastatic, uncertain

 primary site 1 (1%) 

Rhabdomyosarcoma, metastatic,

 skeletal muscle 1 (1%) 1 (1%) 

Sarcoma, metastatic, mesentery 1 (1%) 

Sarcoma, metastatic, skin 1 (1%) 

Salivary glands (94) (98) (97) (98) (99) 

Carcinoma 1 (1%) 

Histiocytic sarcoma 1 (1%) 2 (2%) 

Stomach, forestomach (91) (92) (93) (94) (97) 

Basal cell adenoma 1 (1%) 

Sarcoma 1 (1%) 

Squamous cell carcinoma 1 (1%) 

Squamous cell papilloma 1 (1%) 1 (1%) 1 (1%) 

Stomach, glandular (86) (90) (93) (93) (94) 

Osteosarcoma, metastatic,

 uncertain primary site 1 (1%) 

Cardiovascular System 

Blood vessel (98) (100) (94) (99) (96) 

Heart (98) (100) (100) (99) (100) 

Hemangiosarcoma 1 (1%) 

Histiocytic sarcoma 2 (2%) 

Osteosarcoma, metastatic, bone 1 (1%) 

Sarcoma, metastatic, skin 1 (1%) 

Endocrine System 

Adrenal cortex (92) (98) (99) (99) (99) 

Histiocytic sarcoma 2 (2%) 

Capsule, adenoma 2 (2%) 

Capsule, rhabdomyosarcoma, metastatic,

 skeletal muscle 1 (1%) 

Capsule, sarcoma 1 (1%) 

Adrenal medulla (90) (95) (97) (97) (98) 

Pheochromocytoma benign 3 (3%) 2 (2%) 2 (2%) 

Bilateral, histiocytic sarcoma 1 (1%) 

Bilateral, pheochromocytoma benign 1 (1%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

122 60-Hz Magnetic Fields, NTP TR 488 

TABLE D1 

Summary of the Incidence of Neoplasms in Female Mice in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Endocrine System (continued) 

Islets, pancreatic (87) (95) (94) (94) (94) 

Adenoma 2 (2%) 7 (7%) 2 (2%) 3 (3%) 

Histiocytic sarcoma 2 (2%) 

Rhabdomyosarcoma, metastatic,

 skeletal muscle 1 (1%) 

Parathyroid gland (63) (53) (53) (53) (58) 

Pineal gland (52) (37) (67) (61) (61) 

Histiocytic sarcoma 2 (3%) 

Pituitary gland (83) (92) (87) (89) (93) 

Histiocytic sarcoma 1 (1%) 

Pars distalis, adenoma 16 (19%) 17 (18%) 18 (21%) 21 (24%) 15 (16%) 

Pars distalis, adenoma, multiple 1 (1%) 2 (2%) 1 (1%) 

Pars distalis, histiocytic sarcoma 1 (1%) 

Pars intermedia, adenoma 1 (1%) 1 (1%) 

Thyroid gland (92) (99) (98) (98) (98) 

Adenoma 1 (1%) 1 (1%) 2 (2%) 1 (1%) 

Adenoma, multiple 1 (1%) 

Histiocytic sarcoma 1 (1%) 

Bilateral, adenoma 1 (1%) 

C-cell, adenoma 1 (1%) 

General Body System 

Peritoneum (1) 

Tissue NOS (1) (1) (3) 

Leiomyosarcoma, metastatic, intestine small,

 duodenum 1 (33%) 

Rhabdomyosarcoma 1 (100%) 

Sarcoma 1 (100%) 1 (33%) 

Schwannoma benign 1 (33%) 

Genital System 

Clitoral gland (89) (84) (85) (84) (82) 

Bilateral, histiocytic sarcoma 1 (1%) 

Bilateral, sarcoma 1 (1%) 

Ovary (79) (91) (95) (94) (96) 

Cystadenoma 3 (4%) 3 (3%) 2 (2%) 2 (2%) 

Granulosa cell tumor benign 2 (3%) 3 (3%) 1 (1%) 

Hemangioma 1 (1%) 1 (1%) 2 (2%) 

Hemangiosarcoma 1 (1%) 1 (1%) 

Histiocytic sarcoma 1 (1%) 

Luteoma 1 (1%) 1 (1%) 

Rhabdomyosarcoma, metastatic, intestine

 small, jejunum 1 (1%) 

Bilateral, histiocytic sarcoma 1 (1%) 

Bilateral, luteoma 1 (1%) 1 (1%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

60-Hz Magnetic Fields, NTP TR 488 123 

TABLE D1 

Summary of the Incidence of Neoplasms in Female Mice in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Genital System (continued) 

Uterus (92) (97) (98) (99) (100) 

Hemangioma 1 (1%) 

Hemangiosarcoma 1 (1%) 1 (1%) 

Lymphangioma 1 (1%) 

Rhabdomyosarcoma, metastatic,

 skeletal muscle 1 (1%) 

Bilateral, histiocytic sarcoma 1 (1%) 

Cervix, histiocytic sarcoma 1 (1%) 

Endometrium, polyp stromal 1 (1%) 1 (1%) 1 (1%) 

Vagina (1) (1) 

Hemangiosarcoma 1 (100%) 

Hematopoietic System 

Bone marrow (96) (99) (97) (99) (100) 

Histiocytic sarcoma 1 (1%) 1 (1%) 

Sarcoma 1 (1%) 

Lymph node (19) (15) (4) (14) (12) 

Histiocytic sarcoma 1 (8%) 

Sarcoma, metastatic, skin 1 (5%) 1 (7%) 

Schwannoma malignant, metastatic, skin 1 (5%) 

Bronchial, histiocytic sarcoma 1 (5%) 

Iliac, sarcoma, metastatic, skin 1 (7%) 

Inguinal, histiocytic sarcoma 1 (5%) 1 (8%) 

Lumbar, histiocytic sarcoma 2 (13%) 2 (17%) 

Mediastinal, histiocytic sarcoma 2 (11%) 1 (7%) 1 (8%) 

Renal, histiocytic sarcoma 1 (5%) 2 (13%) 

Lymph node, mandibular (84) (94) (89) (91) (92) 

Histiocytic sarcoma 2 (2%) 1 (1%) 2 (2%) 

Lymph node, mesenteric (83) (88) (89) (92) (95) 

Histiocytic sarcoma 2 (2%) 2 (2%) 4 (4%) 

Plasma cell tumor malignant 1 (1%)

 Rhabdomyosarcoma, metastatic,

 tissue NOS 1 (1%) 

Rhabdomyosarcoma, metastatic, uncertain

 primary site 1 (1%) 

Rhabdomyosarcoma, metastatic,

 skeletal muscle 1 (1%) 

Spleen (91) (93) (95) (93) (99) 

Hemangiosarcoma 1 (1%) 

Histiocytic sarcoma 2 (2%) 2 (2%) 2 (2%) 4 (4%) 

Plasma cell tumor malignant 1 (1%) 1 (1%) 1 (1%) 

Thymus (78) (92) (84) (75) (89) 

Histiocytic sarcoma 1 (1%) 2 (2%) 3 (3%) 

Rhabdomyosarcoma, metastatic, skeletal 

muscle 1 (1%) 

Sarcoma, metastatic, skin 1 (1%) 

Thymoma benign 1 (1%) 1 (1%) 

Thymoma malignant 1 (1%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

124 60-Hz Magnetic Fields, NTP TR 488 

TABLE D1 

Summary of the Incidence of Neoplasms in Female Mice in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Integumentary System 

Mammary gland (94) (98) (99) (99) (98) 

Adenoma 1 (1%) 2 (2%) 1 (1%) 

Carcinoma 1 (1%) 1 (1%) 

Histiocytic sarcoma 1 (1%) 

Skin (99) (100) (100) (100) (100) 

Basal cell carcinoma 1 (1%) 

Fibrosarcoma 1 (1%) 

Hemangioma 1 (1%) 1 (1%) 

Hemangiosarcoma 1 (1%) 1 (1%) 2 (2%) 

Rhabdomyosarcoma, metastatic, uncertain

 primary site 1 (1%) 

Sarcoma 4 (4%) 5 (5%) 2 (2%) 3 (3%) 4 (4%) 

Schwannoma malignant 2 (2%) 1 (1%) 4 (4%) 1 (1%) 2 (2%) 

Trichoepithelioma 1 (1%) 

Musculoskeletal System 

Bone (100) (100) (99) (99) (99) 

Femur, hemangiosarcoma, metastatic, 

spleen 1 (1%) 

Femur, osteosarcoma 1 (1%) 

Sternum, sarcoma, metastatic, mesentery 1 (1%) 

Vertebra, osteosarcoma 1 (1%) 

Skeletal muscle (7) (3) (3) (4) (4) 

Hemangiosarcoma, metastatic, heart 1 (25%) 

Osteosarcoma, metastatic, uncertain primary

 site 1 (25%) 

Rhabdomyosarcoma 3 (43%) 1 (33%) 1 (25%) 

Nervous System 

Brain (99) (100) (98) (98) (100) 

Ventricle, hamartoma, lipomatous 1 (1%) 2 (2%) 1 (1%) 

Respiratory System 

Lung (95) (100) (99) (99) (100) 

Alveolar/bronchiolar adenoma 9 (9%) 6 (6%) 5 (5%) 6 (6%) 

Alveolar/bronchiolar carcinoma 2 (2%) 6 (6%) 2 (2%) 1 (1%) 1 (1%) 

Alveolar/bronchiolar carcinoma, multiple 1 (1%) 

Basal cell carcinoma, metastatic, skin 1 (1%) 

Hepatocellular carcinoma, metastatic, liver 2 (2%) 1 (1%) 

Histiocytic sarcoma 1 (1%) 2 (2%) 2 (2%) 3 (3%) 

Osteosarcoma, metastatic, bone 1 (1%) 1 (1%) 

Plasma cell tumor malignant, metastatic,

 uncertain primary site 1 (1%) 

Rhabdomyosarcoma, metastatic, 

skeletal muscle 1 (1%) 

Sarcoma, metastatic, mesentery 1 (1%) 

Sarcoma, metastatic, skin 1 (1%) 1 (1%) 1 (1%) 1 (1%) 2 (2%) 

Mediastinum, alveolar/bronchiolar carcinoma,

 metastatic, lung 1 (1%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

60-Hz Magnetic Fields, NTP TR 488 125 

TABLE D1 

Summary of the Incidence of Neoplasms in Female Mice in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Respiratory System (continued) 

Lung (continued) (95) (100) (99) (99) (100) 

Mediastinum, histiocytic sarcoma 1 (1%) 

Mediastinum, osteosarcoma, metastatic, bone 1 (1%) 

Mediastinum, schwannoma malignant,

 metastatic, skin 1 (1%) 

Serosa, sarcoma, metastatic, mesentery 1 (1%) 

Nose (99) (100) (99) (100) (99) 

Trachea (94) (100) (98) (99) (98) 

Special Senses System 

Harderian gland (98) (97) (99) (96) (97) 

Adenoma 9 (9%) 7 (7%) 14 (14%) 12 (13%) 12 (12%) 

Carcinoma 2 (2%) 

Histiocytic sarcoma 1 (1%) 

Bilateral, adenoma 1 (1%) 1 (1%) 1 (1%) 

Lacrimal gland (1) 

Bilateral, sarcoma 1 (100%) 

Urinary System 

Kidney (92) (96) (98) (98) (99) 

Histiocytic sarcoma 1 (1%) 1 (1%) 

Osteosarcoma, metastatic, bone 1 (1%) 

Plasma cell tumor malignant, metastatic,

 uncertain primary site 1 (1%) 

Rhabdomyosarcoma, metastatic, 

skeletal muscle 1 (1%) 

Bilateral, histiocytic sarcoma 1 (1%) 3 (3%) 

Urinary bladder (79) (87) (94) (89) (92) 

Carcinoma 1 (1%) 

Systemic Lesions 

Multiple organsb (100) (100) (100) (100) (100) 

Histiocytic sarcoma 2 (2%) 2 (2%) 2 (2%) 6 (6%) 

Lymphoma malignant 32 (32%) 31 (31%) 22 (22%) 26 (26%) 20 (20%) 

Mesothelioma malignant 1 (1%) 

Neoplasm Summary 

Total animals with primary neoplasmsc 78 80 72 71 68 

Total primary neoplasms 132 122 124 117 110 

Total animals with benign neoplasms 52 49 54 49 44 

Total benign neoplasms 68 58 77 71 61 

Total animals with malignant neoplasms 55 58 38 38 44 

Total malignant neoplasms 64 64 47 46 49 

Total animals with metastatic neoplasms 9 8 5 5 6 

Total metastatic neoplasms 14 21 8 8 12

 Total animals with malignant neoplasms

 of uncertain primary site 2 2 2 

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 

Primary neoplasms: all neoplasms except metastatic neoplasms c 
126 60-Hz Magnetic Fields, NTP TR 488 

TABLE D2 

Statistical Analysis of Primary Neoplasms in Female Mice in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Harderian Gland: Adenoma 

Overall rate 10/100 (10%) a 

Adjusted rate 11.0% b 8/100 (8%) 

8.8% 

14/100 (14%) 

15.3% 

12/100 (12%) 

13.4% 

13/100 (13%) 

14.4% 

Terminal rate 7/70 (10%) c 6/74 (8%) 13/79 (17%) 12/74 (16%) 12/77 (16%) 

First incidence (days) 625 

Poly-3 test P=0.309 d 

692 

P=0.406N 

692 

P=0.258 

735 (T) 

P=0.399 

715 

P=0.323 

Harderian Gland: Adenoma or Carcinoma 

Overall rate 12/100 (12%) 8/100 (8%) 14/100 (14%) 12/100 (12%) 13/100 (13%) 

Adjusted rate 13.2% 8.8% 15.3% 13.4% 14.4% 

Terminal rate 9/70 (13%) 6/74 (8%) 13/79 (17%) 12/74 (16%) 12/77 (16%) 

First incidence (days) 625 692 692 735 (T) 715 

Poly-3 test P=0.398 P=0.242N P=0.419 P=0.574 P=0.495 

Liver: Hepatocellular Adenoma 

Overall rate 17/98 (17%) 10/97 (10%) 20/98 (20%) 18/99 (18%) 13/100 (13%) 

Adjusted rate 19.0% 11.3% 22.0% 20.1% 14.3% 

Terminal rate 16/70 (23%) 9/74 (12%) 19/79 (24%) 16/74 (22%) 11/77 (14%) 

First incidence (days) 667 723 578 690 679 

Poly-3 test P=0.246 P=0.111N P=0.371 P=0.498 P=0.262N 

Liver: Hepatocellular Carcinoma 

Overall rate 6/98 (6%) 5/97 (5%) 7/98 (7%) 6/99 (6%) 6/100 (6%) 

Adjusted rate 6.7% 5.6% 7.7% 6.6% 6.6% 

Terminal rate 4/70 (6%) 2/74 (3%) 5/79 (6%) 4/74 (5%) 5/77 (7%) 

First incidence (days) 691 545 578 183 679 

Poly-3 test P=0.554 P=0.502N P=0.511 P=0.607N P=0.610N 

Liver: Hepatocellular Adenoma or Carcinoma 

Overall rate 22/98 (22%) 13/97 (13%) 24/98 (24%) 23/99 (23%) 18/100 (18%) 

Adjusted rate 24.5% 14.5% 26.4% 25.2% 19.8% 

Terminal rate 19/70 (27%) 10/74 (14%) 22/79 (28%) 19/74 (26%) 16/77 (21%) 

First incidence (days) 667 545 578 183 679 

Poly-3 test P=0.217 P=0.067N P=0.451 P=0.522 P=0.284N 

Lung: Alveolar/bronchiolar Adenoma 

Overall rate 9/95 (9%) 6/100 (6%) 0/99 (0%) 5/99 (5%) 6/100 (6%) 

Adjusted rate 10.2% 6.6% 0.0% 5.6% 6.6% 

Terminal rate 7/70 (10%) 4/74 (5%) 0/79 (0%) 4/74 (5%) 6/77 (8%) 

First incidence (days) 551 603 —e 566 735 (T) 

Poly-3 test P=0.363N P=0.271N P=0.002N P=0.190N P=0.275N 

Lung: Alveolar/bronchiolar Carcinoma 

Overall rate 2/95 (2%) 6/100 (6%) 2/99 (2%) 2/99 (2%) 1/100 (1%) 

Adjusted rate 2.3% 6.6% 2.2% 2.2% 1.1% 

Terminal rate 0/70 (0%) 4/74 (5%) 2/79 (3%) 1/74 (1%) 0/77 (0%) 

First incidence (days) 701 496 735 (T) 687 656 

Poly-3 test P=0.287N P=0.154 P=0.678N P=0.684N P=0.483N 
60-Hz Magnetic Fields, NTP TR 488 127 

TABLE D2 

Statistical Analysis of Primary Neoplasms in Female Mice in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Lung: Alveolar/bronchiolar Adenoma or Carcinoma 

Overall rate 11/95 (12%) 11/100 (11%) 2/99 (2%) 7/99 (7%) 7/100 (7%) 

Adjusted rate 12.5% 11.9% 2.2% 7.8% 7.7% 

Terminal rate 7/70 (10%) 7/74 (10%) 2/79 (3%) 5/74 (7%) 6/77 (8%) 

First incidence (days) 551 496 735 (T) 566 656 

Poly-3 test P=0.246N P=0.544N P=0.008N P=0.213N P=0.208N 

Pancreatic Islets: Adenoma 

Overall rate 2/87 (2%) 0/95 (0%) 7/94 (7%) 2/94 (2%) 3/94 (3%) 

Adjusted rate 2.4% 0.0% 8.0% 2.3% 3.5% 

Terminal rate 1/70 (1%) 0/74 (0%) 6/79 (8%) 2/74 (3%) 3/76 (4%) 

First incidence (days) 542 — 694 735 (T) 735 (T) 

Poly-3 test P=0.609 P=0.228N P=0.101 P=0.672N P=0.518 

Pituitary Gland (Pars Distalis): Adenoma 

Overall rate 17/83 (20%) 17/92 (18%) 20/87 (23%) 21/89 (24%) 16/93 (17%) 

Adjusted rate 21.9% 20.1% 24.1% 25.8% 18.7% 

Terminal rate 16/67 (24%) 15/71 (21%) 20/76 (26%) 20/71 (28%) 15/74 (20%) 

First incidence (days) 625 698 735 (T) 730 710 

Poly-3 test P=0.258 P=0.465N P=0.445 P=0.352 P=0.373N 

Skin (Subcutaneous Tissue): Sarcoma 

Overall rate 4/100 (4%) 5/100 (5%) 2/100 (2%) 3/100 (3%) 4/100 (4%) 

Adjusted rate 4.4% 5.4% 2.2% 3.3% 4.4% 

Terminal rate 1/70 (1%) 2/74 (3%) 1/79 (1%) 0/74 (0%) 2/77 (3%) 

First incidence (days) 625 461 513 684 580 

Poly-3 test P=0.404N P=0.506 P=0.336N P=0.504N P=0.640N 

Skin (Subcutaneous Tissue): Fibrosarcoma or Sarcoma 

Overall rate 4/100 (4%) 5/100 (5%) 2/100 (2%) 3/100 (3%) 5/100 (5%) 

Adjusted rate 4.4% 5.4% 2.2% 3.3% 5.4% 

Terminal rate 1/70 (1%) 2/74 (3%) 1/79 (1%) 0/74 (0%) 2/77 (3%) 

First incidence (days) 625 461 513 684 481 

Poly-3 test P=0.404N P=0.506 P=0.336N P=0.504N P=0.505 

All Organs: Hemangiosarcoma 

Overall rate 2/100 (2%) 3/100 (3%) 1/100 (1%) 5/100 (5%) 3/100 (3%) 

Adjusted rate 2.2% 3.3% 1.1% 5.5% 3.3% 

Terminal rate 0/70 (0%) 3/74 (4%) 1/79 (1%) 2/74 (3%) 3/77 (4%) 

First incidence (days) 707 735 (T) 735 (T) 699 735 (T) 

Poly-3 test P=0.131 P=0.499 P=0.498N P=0.219 P=0.499 

All Organs: Hemangioma or Hemangiosarcoma 

Overall rate 2/100 (2%) 5/100 (5%) 2/100 (2%) 7/100 (7%) 5/100 (5%) 

Adjusted rate 2.2% 5.5% 2.2% 7.8% 5.5% 

Terminal rate 0/70 (0%) 4/74 (5%) 2/79 (3%) 4/74 (5%) 5/77 (7%) 

First incidence (days) 707 559 735 (T) 699 735 (T) 

Poly-3 test P=0.084 P=0.222 P=0.691N P=0.084 P=0.220 
	 

	 

128 

c 

60-Hz Magnetic Fields, NTP TR 488 

TABLE D2 

Statistical Analysis of Primary Neoplasms in Female Mice in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

All Organs: Histiocytic Sarcoma 

Overall rate 2/100 (2%) 2/100 (2%) 2/100 (2%) 0/100 (0%) 6/100 (6%) 

Adjusted rate 2.2% 2.2% 2.2% 0.0% 6.5% 

Terminal rate 2/70 (3%) 1/74 (1%) 0/79 (0%) 0/74 (0%) 1/77 (1%) 

First incidence (days) 735 (T) 721 655 — 309 

Poly-3 test P=0.162N P=0.693 P=0.688N P=0.240N P=0.146 

All Organs: Malignant Lymphoma 

Overall rate 32/100 (32%) 31/100 (31%) 22/100 (22%) 26/100 (26%) 20/100 (20%) 

Adjusted rate 34.7% 33.5% 24.0% 28.3% 21.7% 

Terminal rate 23/70 (33%) 23/74 (31%) 20/79 (25%) 20/74 (27%) 15/77 (20%) 

First incidence (days) 461 461 581 467 567 

Poly-3 test P=0.253N P=0.494N P=0.074N P=0.219N P=0.035N 

All Organs: Benign Neoplasms 

Overall rate 52/100 (52%) 49/100 (49%) 54/100 (54%) 49/100 (49%) 44/100 (44%) 

Adjusted rate 56.2% 52.2% 58.6% 54.1% 48.0% 

Terminal rate 44/70 (63%) 38/74 (51%) 49/79 (62%) 46/74 (62%) 38/77 (49%) 

First incidence (days) 542 64 578 566 576 

Poly-3 test P=0.496N P=0.339N P=0.431 P=0.442N P=0.162N 

All Organs: Malignant Neoplasms 

Overall rate 55/100 (55%) 58/100 (58%) 39/100 (39%) 40/100 (40%) 45/100 (45%) 

Adjusted rate 57.6% 59.6% 41.1% 42.5% 46.2% 

Terminal rate 34/70 (49%) 37/74 (50%) 29/79 (37%) 26/74 (35%) 27/77 (35%) 

First incidence (days) 397 461 513 183 309 

Poly-3 test P=0.014N P=0.448 P=0.015N P=0.024N P=0.071N 

All Organs: Benign or Malignant Neoplasms 

Overall rate 78/100 (78%) 80/100 (80%) 72/100 (72%) 71/100 (71%) 68/100 (68%) 

Adjusted rate 81.0% 81.2% 75.8% 74.9% 69.7% 

Terminal rate 54/70 (77%) 56/74 (76%) 60/79 (76%) 55/74 (74%) 49/77 (64%) 

First incidence (days) 397 64 513 183 309 

Poly-3 test P=0.158N P=0.561 P=0.237N P=0.193N P=0.045N 

(T)Terminal sacrifice 

a Number of neoplasm-bearing animals/number of animals examined. Denominator is number of animals examined microscopically for liver, lung, pancreatic 

islets, and pituitary gland; for other tissues, denominator is number of animals necropsied. b	 Poly-3 estimated neoplasm incidence after adjustment for intercurrent mortality 

Observed incidence at terminal kill 

d	 Beneath the control incidence are the P values associated with the trend test; the trend does not include the 10 G intermittent group. 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 negative trend or a lower incidence in an exposure group is indicated by N. e Not applicable; no neoplasms in animal group 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

60-Hz Magnetic Fields, NTP TR 488 129 

TABLE D3 

Summary of the Incidence of Nonneoplastic Lesions in Female Mice in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fieldsa 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Disposition Summary 

Animals initially in study 100 100 100 100 100 

Early deaths 

Accidental deaths 1 1 2 1 

Moribund 6 7 6 7 8 

Natural deaths 23 18 13 18 15 

Survivors 

Died last week of study 1 

Terminal sacrifice 69 74 79 74 77 

Animals examined microscopically 100 100 100 100 100 

Alimentary System 

Esophagus (97) (100) (99) (98) (100) 

Epithelium, hyperplasia, focal 1 (1%) 

Gallbladder (70) (84) (87) (79) (91) 

Infiltration cellular, lymphocyte 1 (1%) 1 (1%) 

Infiltration cellular, mixed cell 1 (1%) 

Epithelium, cyst 5 (7%) 14 (17%) 2 (2%) 3 (4%) 11 (12%) 

Epithelium, cytoplasmic alteration 1 (1%) 

Epithelium, vacuolization cytoplasmic 1 (1%) 

Intestine large, rectum (82) (90) (90) (88) (94) 

Lymphoid tissue, hyperplasia 1 (1%) 

Serosa, inflammation, chronic active 1 (1%) 

Intestine large, cecum (78) (87) (90) (87) (92) 

Lymphoid tissue, hyperplasia 25 (32%) 33 (38%) 35 (39%) 24 (28%) 32 (35%) 

Lymphoid tissue, necrosis 1 (1%) 

Intestine small, duodenum (77) (85) (90) (87) (91) 

Inflammation 1 (1%) 

Muscularis, hypertrophy 1 (1%) 

Peyer’s patch, hyperplasia 1 (1%) 1 (1%) 2 (2%) 

Intestine small, jejunum (79) (86) (89) (91) (92) 

Inflammation 1 (1%) 1 (1%) 

Muscularis, hypertrophy 6 (8%) 8 (9%) 5 (6%) 3 (3%) 7 (8%) 

Peyer’s patch, hyperplasia 3 (4%) 6 (7%) 5 (6%) 7 (8%) 

Peyer’s patch, inflammation 1 (1%) 

Peyer’s patch, necrosis, lymphoid 1 (1%) 

Serosa, inflammation 1 (1%) 1 (1%) 

Intestine small, ileum (78) (85) (90) (87) (93) 

Inflammation 1 (1%) 1 (1%) 2 (2%) 

Artery, inflammation 1 (1%) 

Muscularis, hypertrophy 17 (22%) 16 (19%) 20 (22%) 17 (20%) 15 (16%) 

Peyer’s patch, hyperplasia 4 (5%) 2 (2%) 4 (4%) 4 (5%) 5 (5%) 

Serosa, inflammation 1 (1%) 

Liver (98) (97) (98) (99) (100) 

Angiectasis 1 (1%) 2 (2%) 3 (3%) 

Basophilic focus 2 (2%) 3 (3%) 4 (4%) 2 (2%) 

Basophilic focus, multiple 1 (1%) 1 (1%) 

Clear cell focus 4 (4%) 3 (3%) 7 (7%) 5 (5%) 4 (4%) 

Clear cell focus, multiple 1 (1%) 1 (1%) 1 (1%) 

Developmental malformation 1 (1%) 2 (2%) 1 (1%) 

Eosinophilic focus 5 (5%) 3 (3%) 10 (10%) 10 (10%) 9 (9%) 

Eosinophilic focus, multiple 1 (1%) 1 (1%) 2 (2%) 

a Number of animals examined microscopically at the site and the number of animals with lesion 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

130 60-Hz Magnetic Fields, NTP TR 488 

TABLE D3 

Summary of the Incidence of Nonneoplastic Lesions in Female Mice in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Alimentary System (continued) 

Liver (continued) (98) (97) (98) (99) (100) 

Fibrosis 1 (1%) 

Hematopoietic cell proliferation 1 (1%) 1 (1%) 

Hemorrhage 1 (1%) 1 (1%) 

Hepatodiaphragmatic nodule 1 (1%) 

Infiltration cellular, focal, mast cell 1 (1%) 

Infiltration cellular, focal, lymphocyte 1 (1%) 2 (2%) 1 (1%) 

Infiltration cellular, focal,

 polymorphonuclear 1 (1%) 

Infiltration cellular, focal, mixed cell 53 (54%) 58 (60%) 48 (49%) 48 (48%) 51 (51%) 

Inflammation, focal 1 (1%) 

Mixed cell focus 1 (1%) 2 (2%) 1 (1%) 

Necrosis 4 (4%) 2 (2%) 4 (4%) 5 (5%) 

Pigmentation 1 (1%) 

Bile duct, cyst 1 (1%) 

Hepatocyte, vacuolization cytoplasmic 14 (14%) 15 (15%) 14 (14%) 17 (17%) 14 (14%) 

Sinusoid, centrilobular, dilatation 1 (1%) 

Mesentery (36) (27) (30) (30) (53) 

Hemorrhage 1 (3%) 1 (4%) 1 (3%) 1 (3%) 

Inflammation 1 (2%) 

Arteriole, inflammation 1 (2%) 

Artery, mineralization 1 (3%) 

Fat, inflammation 6 (17%) 4 (15%) 5 (17%) 4 (13%) 14 (26%) 

Fat, necrosis 22 (61%) 16 (59%) 23 (77%) 22 (73%) 31 (58%) 

Pancreas (87) (94) (96) (94) (95) 

Angiectasis, focal 1 (1%) 

Cytoplasmic alteration 1 (1%) 

Infiltration cellular, focal, mixed cell 7 (8%) 12 (13%) 7 (7%) 10 (11%) 12 (13%) 

Infiltration cellular, lymphocyte 5 (6%) 1 (1%) 3 (3%) 5 (5%) 

Inflammation 1 (1%) 1 (1%) 

Lipomatosis 21 (24%) 16 (17%) 23 (24%) 29 (31%) 33 (35%) 

Vacuolization cytoplasmic 12 (14%) 21 (22%) 18 (19%) 16 (17%) 15 (16%) 

Acinus, cytoplasmic alteration 1 (1%) 3 (3%) 4 (4%) 2 (2%) 5 (5%) 

Acinus, degeneration, focal 1 (1%) 

Acinus, hypertrophy, focal 1 (1%) 2 (2%) 1 (1%) 

Artery, inflammation 1 (1%) 1 (1%) 

Duct, cyst 1 (1%) 1 (1%) 3 (3%) 1 (1%) 2 (2%) 

Salivary glands (94) (98) (97) (98) (99) 

Atrophy 1 (1%) 1 (1%) 

Fibrosis 1 (1%) 

Infiltration cellular, lymphocyte 74 (79%) 83 (85%) 77 (79%) 75 (77%) 79 (80%) 

Infiltration cellular, mixed cell 1 (1%) 

Pigmentation 1 (1%) 

Arteriole, inflammation 1 (1%) 

Duct, cyst 1 (1%) 

Duct, cytoplasmic alteration 1 (1%) 

Stomach, forestomach (91) (92) (93) (94) (97) 

Infiltration cellular, lymphocyte 1 (1%) 1 (1%) 

Inflammation 3 (3%) 1 (1%) 1 (1%) 

Ulcer, focal 1 (1%) 1 (1%) 

Epithelium, atrophy 6 (7%) 11 (12%) 5 (5%) 10 (11%) 6 (6%) 

Epithelium, cyst 1 (1%) 

Epithelium, hyperplasia 4 (4%) 5 (5%) 4 (4%) 5 (5%) 5 (5%) 

Muscularis, mineralization, focal 1 (1%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

60-Hz Magnetic Fields, NTP TR 488 131 

TABLE D3 

Summary of the Incidence of Nonneoplastic Lesions in Female Mice in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Alimentary System (continued) 

Stomach, glandular (86) (90) (93) (93) (94) 

Infiltration cellular, lymphocyte 7 (8%) 8 (9%) 3 (3%) 5 (5%) 

Inflammation 1 (1%) 1 (1%) 1 (1%) 1 (1%) 

Ulcer, focal 1 (1%) 1 (1%) 

Epithelium, atrophy 14 (16%) 24 (27%) 20 (22%) 18 (19%) 28 (30%) 

Epithelium, cyst, focal 23 (27%) 19 (21%) 17 (18%) 12 (13%) 20 (21%) 

Epithelium, mineralization 1 (1%) 

Serosa, hemorrhage 1 (1%) 

Cardiovascular System 

Blood vessel (98) (100) (94) (99) (96) 

Aorta, mineralization 2 (2%) 

Aorta, adventitia, inflammation, chronic

 active 1 (1%) 

Heart (98) (100) (100) (99) (100) 

Inflammation 1 (1%) 

Artery, inflammation 1 (1%) 1 (1%) 1 (1%) 

Artery, mineralization 1 (1%) 

Atrium, infiltration cellular, lymphocyte 1 (1%) 

Atrium, thrombosis 1 (1%) 1 (1%) 

Epicardium, inflammation, chronic active 1 (1%) 

Myocardium, degeneration 1 (1%) 4 (4%) 1 (1%) 1 (1%) 

Myocardium, inflammation 1 (1%) 

Myocardium, mineralization 1 (1%) 3 (3%) 1 (1%) 

Myocardium, necrosis, focal 1 (1%) 

Valve, thrombosis 1 (1%) 1 (1%) 

Endocrine System 

Adrenal cortex (92) (98) (99) (99) (99) 

Cytoplasmic alteration, focal 1 (1%) 

Degeneration, fatty 1 (1%) 

Hematopoietic cell proliferation 2 (2%) 

Infiltration cellular, lymphocyte 1 (1%) 

Inflammation 1 (1%) 

Bilateral, capsule, hyperplasia 88 (96%) 88 (90%) 85 (86%) 89 (90%) 94 (95%) 

Bilateral, capsule, mineralization 1 (1%) 

Bilateral, zona fasciculata, hypertrophy,

 focal 1 (1%) 

Bilateral, zona glomerulosa, hyperplasia,

 focal 1 (1%) 

Bilateral, zona reticularis, degeneration,

 fatty 2 (2%) 4 (4%) 2 (2%) 

Capsule, hyperplasia 3 (3%) 8 (8%) 12 (12%) 9 (9%) 5 (5%) 

Zona fasciculata, hyperplasia, focal 1 (1%) 3 (3%) 

Zona fasciculata, hypertrophy, diffuse 1 (1%) 

Zona fasciculata, hypertrophy, focal 2 (2%) 2 (2%) 5 (5%) 

Zona reticularis, degeneration, fatty 2 (2%) 2 (2%) 3 (3%) 1 (1%) 

Adrenal medulla (90) (95) (97) (97) (98) 

Hyperplasia 3 (3%) 8 (8%) 2 (2%) 3 (3%) 

Bilateral, amyloid deposition 1 (1%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

132 60-Hz Magnetic Fields, NTP TR 488 

TABLE D3 

Summary of the Incidence of Nonneoplastic Lesions in Female Mice in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Endocrine System (continued) 

Islets, pancreatic (87) (95) (94) (94) (94) 

Degeneration 1 (1%) 

Hyperplasia 40 (46%) 60 (63%) 42 (45%) 48 (51%) 47 (50%) 

Infiltration cellular, focal, mixed cell 2 (2%) 1 (1%) 3 (3%) 1 (1%) 

Infiltration cellular, lymphocyte 1 (1%) 

Inflammation, chronic active 1 (1%) 

Parathyroid gland (63) (53) (53) (53) (58) 

Cyst 1 (2%) 1 (2%) 

Degeneration 1 (2%) 

Hyperplasia 11 (17%) 8 (15%) 7 (13%) 6 (11%) 8 (14%) 

Infiltration cellular, lymphocyte 2 (3%) 1 (2%) 2 (4%) 2 (4%) 

Infiltration cellular, mixed cell 1 (2%) 

Inflammation, focal 2 (4%) 

Vacuolization cytoplasmic 1 (2%) 1 (2%) 

Pineal gland (52) (37) (67) (61) (61) 

Hyperplasia 1 (2%) 

Infiltration cellular, lymphocyte 1 (2%) 

Inflammation 1 (2%) 

Pituitary gland (83) (92) (87) (89) (93) 

Hemorrhage 1 (1%) 

Pars distalis, cyst 2 (2%) 3 (3%) 1 (1%) 4 (4%) 

Pars distalis, hyperplasia, diffuse 1 (1%) 

Pars distalis, hyperplasia, focal 37 (45%) 50 (54%) 33 (38%) 35 (39%) 35 (38%) 

Pars distalis, hypertrophy, focal 3 (3%) 1 (1%) 1 (1%) 

Rathke’s cleft, cyst 1 (1%) 

Thyroid gland (92) (99) (98) (98) (98) 

Infiltration cellular, lymphocyte 3 (3%) 

Inflammation, focal 2 (2%) 3 (3%) 4 (4%) 2 (2%) 

Bilateral, infiltration cellular, lymphocyte 1 (1%) 

Follicle, cyst 21 (23%) 21 (21%) 25 (26%) 22 (22%) 37 (38%) 

Follicular cell, hyperplasia, focal 3 (3%) 5 (5%) 1 (1%) 1 (1%) 

Follicular cell, hypertrophy, diffuse 2 (2%) 

General Body System 

Tissue NOS (1) (1) (3) 

Inflammation, chronic active 1 (33%) 

Genital System 

Clitoral gland (89) (84) (85) (84) (82) 

Atrophy 25 (28%) 19 (23%) 16 (19%) 21 (25%) 17 (21%) 

Cyst 29 (33%) 26 (31%) 15 (18%) 18 (21%) 19 (23%) 

Inflammation 1 (1%) 1 (1%) 

Arteriole, inflammation 1 (1%) 

Bilateral, atrophy 55 (62%) 56 (67%) 61 (72%) 55 (65%) 57 (70%) 

Bilateral, cyst 55 (62%) 56 (67%) 66 (78%) 58 (69%) 52 (63%) 

Bilateral, inflammation 2 (2%) 1 (1%) 

Ovary (79) (91) (95) (94) (96) 

Amyloid deposition 1 (1%) 

Angiectasis 2 (2%) 3 (3%) 3 (3%) 

Atrophy 3 (4%) 1 (1%) 1 (1%) 2 (2%) 1 (1%) 

Cyst 20 (25%) 23 (25%) 28 (29%) 32 (34%) 21 (22%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

60-Hz Magnetic Fields, NTP TR 488 133 

TABLE D3 

Summary of the Incidence of Nonneoplastic Lesions in Female Mice in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Genital System (continued) 

Ovary (continued) (79) (91) (95) (94) (96) 

Hemorrhage 1 (1%) 1 (1%) 1 (1%) 

Infiltration cellular, mast cell 1 (1%) 

Infiltration cellular, mixed cell 1 (1%) 

Inflammation, chronic active 2 (2%) 

Mineralization 1 (1%) 1 (1%) 

Pigmentation 1 (1%) 

Thrombosis 1 (1%) 1 (1%) 

Bilateral, amyloid deposition 1 (1%) 

Bilateral, atrophy 1 (1%) 2 (2%) 2 (2%) 3 (3%) 2 (2%) 

Bilateral, cyst 2 (3%) 2 (2%) 1 (1%) 3 (3%) 

Germinal epithelium, hyperplasia 1 (1%) 

Interstitial cell, hyperplasia 1 (1%) 

Uterus (92) (97) (98) (99) (100) 

Amyloid deposition 1 (1%) 1 (1%) 

Angiectasis 1 (1%) 3 (3%) 2 (2%) 3 (3%) 

Hemorrhage 1 (1%) 1 (1%) 

Hydrometra 24 (26%) 18 (19%) 16 (16%) 20 (20%) 22 (22%) 

Inflammation 2 (2%) 

Inflammation, chronic 1 (1%) 

Thrombosis 1 (1%) 

Bilateral, atrophy 1 (1%) 

Bilateral, hydrometra 24 (26%) 15 (15%) 24 (24%) 21 (21%) 26 (26%) 

Bilateral, endometrium, amyloid deposition 1 (1%) 

Bilateral, endometrium, hyperplasia, cystic 32 (35%) 44 (45%) 41 (42%) 45 (45%) 38 (38%) 

Cervix, angiectasis 1 (1%) 

Endometrium, angiectasis 1 (1%) 

Endometrium, hyperplasia, cystic 22 (24%) 27 (28%) 26 (27%) 21 (21%) 24 (24%) 

Hematopoietic System 

Bone marrow (96) (99) (97) (99) (100) 

Angiectasis 1 (1%) 2 (2%) 

Atrophy 1 (1%) 1 (1%) 

Hyperplasia 23 (24%) 13 (13%) 13 (13%) 14 (14%) 19 (19%) 

Infiltration cellular, focal, lymphocyte 1 (1%) 

Myelofibrosis 10 (10%) 18 (18%) 17 (18%) 10 (10%) 21 (21%) 

Necrosis 1 (1%) 

Myeloid cell, hyperplasia 3 (3%) 

Lymph node (19) (15) (4) (14) (12) 

Ectasia 2 (11%) 2 (13%) 2 (50%) 1 (7%) 1 (8%) 

Hemorrhage 1 (5%) 2 (13%) 1 (25%) 1 (7%) 1 (8%) 

Hyperplasia, reticulum cell 1 (8%) 

Infiltration cellular, mast cell 1 (25%) 

Infiltration cellular, histiocyte 1 (7%) 1 (8%) 

Lumbar, ectasia 3 (16%) 1 (7%) 1 (25%) 2 (14%) 

Lumbar, hemorrhage 4 (21%) 1 (25%) 1 (7%) 

Lumbar, pigmentation 1 (5%) 

Mediastinal, hemorrhage 1 (7%) 

Mediastinal, infiltration cellular,

 mixed cell 1 (7%) 

Renal, ectasia 1 (7%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

134 60-Hz Magnetic Fields, NTP TR 488 

TABLE D3 

Summary of the Incidence of Nonneoplastic Lesions in Female Mice in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Hematopoietic System (continued) 

Lymph node, mandibular (84) (94) (89) (91) (92) 

Atrophy 3 (4%) 7 (7%) 4 (4%) 4 (4%) 3 (3%) 

Hemorrhage 2 (2%) 2 (2%) 1 (1%) 2 (2%) 3 (3%) 

Hyperplasia 8 (10%) 10 (11%) 12 (13%) 4 (4%) 4 (4%) 

Hyperplasia, reticulum cell 2 (2%) 1 (1%) 2 (2%) 2 (2%) 

Infiltration cellular, plasma cell 2 (2%) 1 (1%) 2 (2%) 1 (1%) 1 (1%) 

Infiltration cellular, histiocyte 1 (1%) 1 (1%) 

Infiltration cellular, mixed cell 2 (2%) 1 (1%) 2 (2%) 1 (1%) 1 (1%) 

Pigmentation 22 (26%) 9 (10%) 18 (20%) 10 (11%) 18 (20%) 

Lymph node, mesenteric (83) (88) (89) (92) (95) 

Angiectasis 1 (1%) 1 (1%) 

Atrophy 12 (14%) 10 (11%) 24 (27%) 21 (23%) 22 (23%) 

Ectasia 3 (4%) 4 (4%) 2 (2%) 

Hemorrhage 3 (4%) 2 (2%) 4 (4%) 4 (4%) 2 (2%) 

Hyperplasia 2 (2%) 1 (1%) 4 (4%) 2 (2%) 

Hyperplasia, reticulum cell 3 (4%) 7 (8%) 13 (15%) 8 (9%) 15 (16%) 

Infiltration cellular, plasma cell 5 (6%) 4 (5%) 2 (2%) 1 (1%) 6 (6%) 

Infiltration cellular, histiocyte 50 (60%) 45 (51%) 47 (53%) 43 (47%) 41 (43%) 

Infiltration cellular, mixed cell 4 (5%) 1 (1%) 2 (2%) 5 (5%) 5 (5%) 

Inflammation, focal 1 (1%) 

Artery, inflammation 1 (1%) 

Spleen (91) (93) (95) (93) (99) 

Congestion 1 (1%) 

Fibrosis, focal 1 (1%) 

Hematopoietic cell proliferation 74 (81%) 77 (83%) 87 (92%) 83 (89%) 92 (93%) 

Infarct 1 (1%) 1 (1%) 

Infiltration cellular, mast cell 1 (1%) 

Infiltration cellular, plasma cell 1 (1%) 

Pigmentation 17 (19%) 6 (6%) 8 (8%) 12 (13%) 12 (12%) 

Lymphoid follicle, atrophy 6 (7%) 4 (4%) 7 (7%) 3 (3%) 3 (3%) 

Lymphoid follicle, hyperplasia 31 (34%) 31 (33%) 32 (34%) 34 (37%) 40 (40%) 

Lymphoid follicle, necrosis 1 (1%) 1 (1%) 

Red pulp, atrophy 2 (2%) 3 (3%) 

Thymus (78) (92) (84) (75) (89) 

Angiectasis 1 (1%) 2 (2%) 3 (4%) 3 (4%) 2 (2%) 

Atrophy 22 (28%) 20 (22%) 24 (29%) 29 (39%) 27 (30%) 

Cyst, focal 5 (6%) 2 (2%) 3 (4%) 9 (12%) 3 (3%) 

Hemorrhage 1 (1%) 2 (2%) 

Hyperplasia, lymphoid 31 (40%) 19 (21%) 20 (24%) 24 (32%) 25 (28%) 

Artery, inflammation 1 (1%) 

Thymocyte, necrosis 1 (1%) 3 (3%) 

Integumentary System 

Mammary gland (94) (98) (99) (99) (98) 

Hyperplasia 3 (3%) 3 (3%) 5 (5%) 2 (2%) 3 (3%) 

Infiltration cellular, lymphocyte 1 (1%) 1 (1%) 

Artery, inflammation 1 (1%) 

Duct, dilatation 10 (11%) 15 (15%) 16 (16%) 17 (17%) 12 (12%) 

Skin (99) (100) (100) (100) (100) 

Hemorrhage 1 (1%) 

Ulcer, focal 2 (2%) 

Artery, inflammation 1 (1%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

60-Hz Magnetic Fields, NTP TR 488 135 

TABLE D3 

Summary of the Incidence of Nonneoplastic Lesions in Female Mice in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Musculoskeletal System 

Skeletal muscle (7) (3) (3) (4) (4) 

Degeneration 1 (33%) 

Necrosis 1 (14%) 

Nervous System 

Brain (99) (100) (98) (98) (100) 

Infiltration cellular, focal, mixed cell 1 (1%) 

Artery, inflammation 1 (1%) 

Cerebellum, developmental malformation, 

focal 1 (1%) 

Choroid plexus, infiltration cellular,

 lymphocyte 1 (1%) 

Hypothalamus, compression 2 (2%) 3 (3%) 3 (3%) 

Hypothalamus, hemorrhage 1 (1%) 

Thalamus, infiltration cellular, lymphocyte 1 (1%) 

Thalamus, mineralization 47 (47%) 68 (68%) 55 (56%) 60 (61%) 72 (72%) 

Ventricle, hydrocephalus 2 (2%) 

Ventricle, infiltration cellular, lymphocyte 1 (1%) 

Respiratory System 

Lung (95) (100) (99) (99) (100) 

Congestion 1 (1%) 1 (1%) 

Fibrosis 1 (1%) 

Hemorrhage 2 (2%) 1 (1%) 1 (1%) 

Infiltration cellular, lymphocyte 32 (34%) 37 (37%) 33 (33%) 34 (34%) 30 (30%) 

Inflammation, focal 2 (2%) 1 (1%) 1 (1%) 1 (1%) 1 (1%) 

Metaplasia, focal, osseous 1 (1%) 1 (1%) 

Alveolar epithelium, hyperplasia, focal 4 (4%) 1 (1%) 2 (2%) 1 (1%) 

Alveolus, infiltration cellular, histiocyte 1 (1%) 4 (4%) 1 (1%) 2 (2%) 

Artery, mineralization 2 (2%) 

Serosa, inflammation 2 (2%) 

Trachea (94) (100) (98) (99) (98) 

Artery, inflammation 1 (1%) 

Special Senses System 

Eye (2) (2) (1) (1) (2) 

Cornea, inflammation 2 (100%) 1 (100%) 

Lens, degeneration 1 (50%) 

Lens, mineralization 1 (100%) 

Harderian gland (98) (97) (99) (96) (97) 

Infiltration cellular, lymphocyte 13 (13%) 12 (12%) 18 (18%) 16 (17%) 20 (21%) 

Bilateral, infiltration cellular, lymphocyte 14 (14%) 11 (11%) 18 (18%) 16 (17%) 16 (16%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

136 60-Hz Magnetic Fields, NTP TR 488 

TABLE D3 

Summary of the Incidence of Nonneoplastic Lesions in Female Mice in the 2-Year Whole-Body Exposure Study 

of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Urinary System 

Kidney (92) (96) (98) (98) (99) 

Hydronephrosis 1 (1%) 1 (1%) 1 (1%) 

Infarct, acute 1 (1%) 

Infiltration cellular, lymphocyte 1 (1%) 1 (1%) 

Artery, inflammation 1 (1%) 

Bilateral, artery, inflammation 1 (1%) 

Bilateral, artery, mineralization 1 (1%) 

Bilateral, artery, cortex, inflammation 1 (1%) 

Bilateral, cortex, cyst, multiple 1 (1%) 

Bilateral, cortex, infiltration cellular,

 lymphocyte 11 (12%) 8 (8%) 7 (7%) 7 (7%) 8 (8%) 

Bilateral, cortex, inflammation 1 (1%) 

Bilateral, cortex, mineralization 1 (1%) 1 (1%) 

Bilateral, cortex, renal tubule,

 accumulation, hyaline droplet 2 (2%) 3 (3%) 

Bilateral, cortex, renal tubule, degeneration 7 (8%) 11 (11%) 7 (7%) 8 (8%) 9 (9%) 

Bilateral, cortex, renal tubule, dilatation 1 (1%) 1 (1%) 1 (1%) 1 (1%) 

Bilateral, cortex, renal tubule,

 vacuolization cytoplasmic 2 (2%) 

Bilateral, glomerulus, amyloid deposition 1 (1%) 

Bilateral, glomerulus, inflammation 1 (1%) 1 (1%) 

Bilateral, medulla, infiltration cellular,

 lymphocyte 26 (28%) 29 (30%) 38 (39%) 31 (32%) 37 (37%) 

Bilateral, medulla, mineralization 1 (1%) 1 (1%) 

Cortex, cyst 3 (3%) 

Cortex, infiltration cellular, plasma cell 1 (1%) 

Cortex, infiltration cellular, lymphocyte 13 (14%) 9 (9%) 14 (14%) 8 (8%) 8 (8%) 

Cortex, infiltration cellular, mixed cell 1 (1%) 

Cortex, metaplasia, focal, osseous 4 (4%) 3 (3%) 3 (3%) 3 (3%) 3 (3%) 

Cortex, necrosis 1 (1%) 

Cortex, renal tubule, degeneration 3 (3%) 7 (7%) 4 (4%) 4 (4%) 4 (4%) 

Cortex, renal tubule, dilatation 2 (2%) 

Medulla, cyst 1 (1%) 

Medulla, infiltration cellular, lymphocyte 21 (23%) 24 (25%) 18 (18%) 27 (28%) 20 (20%) 

Medulla, inflammation 1 (1%) 1 (1%) 

Medulla, mineralization 2 (2%) 1 (1%) 1 (1%) 1 (1%) 

Pelvis, calculus, microscopic observation only 3 (3%) 2 (2%) 2 (2%) 1 (1%) 2 (2%) 

Urinary bladder (79) (87) (94) (89) (92) 

Infiltration cellular, plasma cell 1 (1%) 

Infiltration cellular, lymphocyte 8 (10%) 3 (3%) 4 (4%) 6 (7%) 5 (5%) 

Arteriole, inflammation 1 (1%) 1 (1%) 

Artery, inflammation 1 (1%) 

Serosa, inflammation, chronic active 1 (1%) 

 


 


 


 


 


 


 


 


 

137 

APPENDIX E
 

MAGNETIC FIELD PRODUCTION AND MONITORING
 

METHODS ............................................................... 138
 

FACILITY VALIDATION ....................................................... 139
 

FIGURE E1 Exposure Facility Floor Plan ......................................... 140
 

FIGURE E2 Magnetic Fields Unit ............................................... 141
 

TABLE E1 Summary of Average Field Intensities and Exposure Conditions 

in the 2-Year Whole-Body Exposure Studies of 60-Hz Magnetic Fields ............. 142
 

TABLE E2 Summary of Earth's Static Magnetic Field Intensities Measured Within Exposure Rooms 

Prior to the 2-Year Whole-Body Exposure Studies of 60-Hz Magnetic Fields ......... 144
 

TABLE E3 Summary of Central Direct-Current Magnetic Fields 

Parallel to Alternating-Current Magnetic Fields 

in the 2-Year Whole-Body Exposure Studies of 60-Hz Magnetic Fields ............. 145
 

 

138 60-Hz Magnetic Fields, NTP TR 488 

MAGNETIC FIELD PRODUCTION AND MONITORING
 

METHODS 

The magnetic field exposure facility consisted of five animal exposure rooms (one of these had coils that did 

not carry a current and served as a control animal exposure room), storage rooms, cage washing facilities, a 

necropsy facility, an engineering control room for the generation and monitoring of fields and room 

conditions, access corridors, and showers and changing rooms for laboratory technicians (Figure E1). 

Offset coils in the exposure rooms and in storage rooms between the exposure rooms were used to minimize 

stray fields. The engineering control room contained the generator that produced the current that supplied 

the coils in each exposure room and monitors for induced and stray 60-Hz magnetic fields and for the 

collection of humidity, temperature, sound, vibration, ventilation, and light data. The engineering control 

room was outside the range of stray magnetic fields above 1 mG. 

Each coil set consisted of seven pairs of rectangular, vertically oriented coils connected in series with 

compensating capacitors between each coil. The compensating capacitors minimized the voltage required to 

circulate the necessary current through the coils by canceling the inductive reactance at 60 Hz. Capacitors 

also controlled the voltage differential between coils and thus minimized the electrical field produced. Coils 

were spaced uniformly through the room and were 4 feet tall and 8 feet wide, weighing approximately 

80 kilograms. The coils in the five exposure room were driven individually by five source controllers 

located in the engineering control room. Coil sets were stacked one above the other; the bottom coils 

produced a linear 60-Hz magnetic field in one direction while the top coils produced a similar field in the 

opposite direction (Figure E2). The coil position in each room protected against field overlap between 

rooms. The opposing fields produced by the coil sets largely canceled each other outside the area of the 

exposure room. Additional field cancellation was provided by horizontally positioned steering coils located 

at the ends of each coil set. 

Coils were held in place by fiberglass supports and were protected from moisture by PlexiglasTM enclosures. 

DurometerTM neoprene pads between the coils and supports isolated coil vibrations. Each coil set was 

controlled from the engineering control room. The fields in three rooms had intensities of 0.02, 2, and 

10 G, and the field in a fourth room was manipulated to produce an intermittent 10-G field (1 hour on and 

1 hour off). Harmonic distortion was less than 3%. A fifth room with an identical coil apparatus that was 

not operating served as the control animal exposure room. Fiberglass cage racks were constructed to 

prevent disruption of the induced magnetic fields. The stainless steel automatic watering system was 

designed and configured to eliminate possible current loops. Fiberglass guides and floor plates were located 

in each room to provide precise alignment of racks and cages within the magnetic field. Racks held equal 

numbers of polycarbonate cages in either the top or the bottom field of the coil sets (Figure E2). Cages 

were alternated between the top and bottom linear horizontal fields on a weekly basis. 

Induced alternating 60-Hz magnetic fields were monitored by a MultiWaveTM Monitoring System (Electric 

Research and Management, Inc., Pittsburgh, PA), which consisted of a microcomputer, an external tie-in, 

and data multiplexors that were located in the control room. In animal exposure rooms, monitoring system 

components included a series of three-axis alternating-current magnetic field probes (two per room), 

alternating-current voltage probes, and environmental sensor probes (to measure rack vibration, noise, light 

intensity, temperature, and humidity). The magnetic probes, which were located at the end of each 

exposure module in the center of the steering coils to detect faults in the coils, allowed monitoring of the 

ambient magnetic fields during the “off” periods of intermittent exposure and during daily field shutdowns. 

The computer program (WAVE-C) continuously monitored and collected sensor data. Data samples were 

electronically stored every 30 minutes, and data were off-loaded from the system on a daily basis. The 
60-Hz Magnetic Fields, NTP TR 488 139 

system was equipped with alarms to alert project personnel in the event that measured parameters deviated 

from set ranges. 

Average field intensities measured during the 2-year studies are given in Table E1. All daily mean 

intensities were within 10% of the target; the maximum magnetic field intensity in the control animal 

exposure room did not exceed 1.3 mG. The background sound levels were uniform between exposure 

rooms and the vibrations caused by the force of the alternating fields on the metal components were damped 

almost completely. The groups of animals were rotated from room to room every 10 weeks, so each of the 

five animal exposure rooms served as the control exposure room twice during the 2-year studies (a final 

rotation was not carried out for the last 4 weeks). This served to minimize the environmental effect of each 

room and the variation between the earth’s static magnetic fields with different exposure regimens. 

FACILITY VALIDATION 

Following installation of the exposure systems, measurements were made to verify that the systems were 

operating within specifications. These included measurements of magnetic field level, vibration, surface 

temperature rise, electric field levels, and sound levels; measurements of the effect of the transient 

suppression circuit were made on the prototype in Pittsburgh (Electric Research and Management, Inc., 

1993). During a preliminary study, an animal rack equipped with eight thermocouples was placed in each 

animal room to record cage temperatures when fields were on and off. No differences in temperature were 

found with magnetic field exposures. In addition, the exposure system was validated by a representative of 

the National Institute of Standards and Technology (NIST), who found that the intensities and spatial 

uniformity of the earth’s static magnetic fields within the animal exposure area were consistent with the 

expected intensities in the Chicago area (approximately 300 to 400 mG) (Table E2). Using an NIST 

fluxgate magnetometer, measurements were made of the direct-current magnetic field component that was 

parallel to the direction of the alternating-current magnetic field in each exposure room in a north-south 

direction. The measurements were performed in the top and bottom coil systems at the level of the rat and 

mouse enclosures in each exposure bay. The results are presented in Table E3. The calibration uncertainty 

of the fluxgate magnetometer was estimated to be less than 2%; however, the measurements are sensitive to 

probe alignment because of the nonuniformity of the field and the presence of a significant vertical magnetic 

field component. The full NIST validation report from the National Institute of Environmental Health 

Sciences appears in Appendix F. 
140 60-HZ Magnetic Fields, NTP TR 488
 

FIGURE E1 

Exposure Facility Floor Plan 
60-HZ Magnetic Fields, NTP TR 488
 141 

FIGURE E2 

Magnetic Fields Unit 
142 60-Hz Magnetic Fields, NTP TR 488 

TABLE E1 

Summary of Average Field Intensities and Exposure Conditions 

in the 2-Year Whole-Body Exposure Studies of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Magnetic Field Intensity (mG) 

Fields on (North) a Average — 20.05 2,002.92 10,047.49 10,019.79 

Minimum — 18.89 1,920.68 9,808.90 9,774.68 

Maximum — 21.05 2,076.51 10,272.18 10,397.20 

Fields off (North) 

Average 0.39 0.36 0.35 0.62 0.51 

Minimum 0.04 0.07 0.07 0.13 0.19 

Maximum 0.96 0.92 0.74 1.70 1.04 

Fields on (South) 

Average — 20.01 2,007.93 10,056.70 10,023.40 

Minimum — 18.86 1,936.99 9,840.86 7,534.99 

Maximum — 22.04 2,078.27 10,313.29 10,382.35 

Fields off (South) 

Average 0.62 0.66 0.64 0.68 0.72 

Minimum 0.03 0.04 0.07 0.18 0.15 

Maximum 1.26 1.35 1.34 1.64 1.44 

Sound Levels (dB) 

Fields on 

Average — 70.29 70.24 70.24 70.26 

Minimum — 60.00 60.00 60.00 60.00 

Maximum — 77.95 77.94 77.86 78.20 

Fields off 

Average 70.01 70.07 70.14 70.16 70.16 

Minimum 60.00 60.00 60.00 60.00 60.00 

Maximum 78.20 78.20 78.20 78.20 78.20 
60-Hz Magnetic Fields, NTP TR 488 143 

TABLE E1 

Summary of Average Field Intensities and Exposure Conditions 

in the 2-Year Whole-Body Exposure Studies of 60-Hz Magnetic Fields 

Control 0.02 G 2 G 10 G 10 G 

Intermittent 

Vibrationsb 

Fields on 

Average — 0.00148 0.00105 0.00110 0.00143 

Minimum — 0.00000 0.00000 0.00000 0.00000 

Maximum — 0.01000 0.02500 0.02700 0.08900 

Fields off 

Average 0.00148 0.00170 0.00125 0.00018 0.00156 

Minimum 0.00000 0.00000 0.00000 0.00000 0.00000 

Maximum 0.10600 0.09600 0.10800 0.17500 0.10700 

Lights on/fields on 

Average — 0.00152 0.00103 0.00107 0.00145 

Minimum — 0.00000 0.00000 0.00000 0.00000 

Maximum — 0.00800 0.02500 0.02400 0.08900 

Lights on/fields off 

Average 0.00155 0.00171 0.00125 0.00123 0.00156 

Minimum 0.00000 0.00000 0.00000 0.00000 0.00000 

Maximum 0.10600 0.09600 0.10800 0.17500 0.10700 

Lights off/fields on 

Average — 0.00145 0.00105 0.00112 0.00142 

Minimum — 0.00000 0.00000 0.00000 0.00000 

Maximum — 0.01000 0.00800 0.02700 0.01600 

Lights off/fields off 

Average 0.00141 0.00100 0.00107 0.00110 0.00103 

Minimum 0.00000 0.00000 0.00000 0.00000 0.00000 

Maximum 0.00900 0.00100 0.00200 0.14800 0.00200 

a Not applicable b 2 Expressed as percent of gravity (9.8 m/s ) 
144 60-Hz Magnetic Fields, NTP TR 488 

TABLE E2 

Summary of Earth's Static Magnetic Field Intensities Measured Within Exposure Rooms 

Prior to the 2-Year Whole-Body Exposure Studies of 60-Hz Magnetic Fields 

Field Intensity (G) 

Rack Bay Top Bottom 

Room 1 1 

2 

3 

4 

5 

6 

0.118 

0.128 

0.148 

0.155 

0.159 

0.162 

0.008 

0.013 

0.129 

0.034 

0.191 

0.169 

Room 2 1 

2 

3 

4 

5 

6 

0.113 

0.111 

0.126 

0.177 

0.205 

0.206 

0.023 

!0.035 

0.041 

0.271 

0.324 

0.328 

Room 3 1 

2 

3 

4 

5 

6 

0.143 

0.148 

0.158 

0.162 

0.172 

0.175 

0.091 

0.104 

0.144 

0.183 

0.220 

0.217 

Room 4 1 

2 

3 

4 

5 

6 

0.207 

0.199 

0.190 

0.169 

0.143 

0.125 

0.217 

0.168 

0.197 

0.179 

0.068 

0.002 

Room 5 1 

2 

3 

4 

5 

6 

0.189 

0.205 

0.183 

0.148 

0.111 

0.094 

0.259 

0.243 

0.135 

!0.051 

!0.123 

!0.086 
60-Hz Magnetic Fields, NTP TR 488 145 

TABLE E3 

Summary of Central Direct-Current Magnetic Fields Parallel to Alternating-Current Magnetic Fields 

in the 2-Year Whole-Body Exposure Studies of 60-Hz Magnetic Fields 

Field Intensity (G) 

Rack Bay Top Bottom 

Room 1 1 

2 

3 

4 

5 

6 

0.115 

0.126 

0.144 

0.151 

0.157 

0.161 

0.012 

!0.016 

0.136 

0.037 

0.175 

0.171 

Room 2 1 

2 

3 

4 

5 

6 

0.117 

0.108 

0.116 

0.162 

0.198 

0.210 

0.050 

!0.050 

0.028 

0.160 

0.347 

0.379 

Room 3 1 

2 

3 

4 

5 

6 

0.143 

0.145 

0.151 

0.161 

0.168 

0.170 

0.092 

0.110 

0.134 

0.186 

0.219 

0.214 

Room 4 1 

2 

3 

4 

5 

6 

0.206 

0.197 

0.189 

0.169 

0.146 

0.126 

0.221 

0.174 

0.190 

0.187 

0.086 

0.013 

Room 5 1 

2 

3 

4 

5 

6 

0.182 

0.205 

0.198 

0.167 

0.120 

0.090 

0.246 

0.257 

0.189 

0.028 

!0.114 

!0.127 
146 60-Hz Magnetic Fields, NTP TR 488 

 


 


 


 


 

147 

APPENDIX F
 

MEASUREMENT OF 60-HZ MAGNETIC
 

AND ELECTRIC FIELDS
 

AT THE ILLINOIS INSTITUTE
 

OF TECHNOLOGY RESEARCH INSTITUTE
 

(Reprinted with permission of the National Institute of Standards and Technology) 
148 60-Hz Magnetic Fields, NTP TR 488 
60-Hz Magnetic Fields, NTP TR 488 149 

Measurement of 60-Hz Magnetic and Electric Fields 


at the lllinois Institute of Technology Research Institute 


Chicago, Illinois 


May 26-27, 1993 


Applied Electrical Measurements 

Report No. 811-3-96 

Prepared by 

Martin Misakian 


Electricity Division 


National Institute of Standards and Technology 


Reviewed by: ~v&.--7~ William E. Anderson, Leader 

Applied Electrical Measurements Group 

Electricity Division 

Approved by: ::--:---=~'-·=,----' '"'-~--=-=--:----==-=--­ Oskars Petersons, Chief 


Electricity Division 

150 60-Hz Magnetic Fields, NTP TR 488 

Measurements of 60-Hz Magnetic and Electric Fields 


at the Illinois Institute of Technology Research Institute 


This report describes a visit to the Illinois Institute of Technology Research Institute 

(IITRI) in Chicago, Illinois during which 60-Hz magnetic fields were characterized in . 

exposure systems that will be used to examine biological effects in rats and mice. Spot 

measurements of 60-Hz electric fields and de magnetic fields were also performed. 

Briefly, there are five exposure systems located in separate rooms as shown in Figure 1 

(provided by IITRI). Each exposure system consists of, in part, two sets of seven 

rectangular coils with a common axis for each set. The coils are stacked in a vertical 

configuration as indicated in the sketch shown in Figure 2, with the axis of each coil 

system in the north-south direction. The two coil systems are connected in series and 

the current is routed such that the direction of the axial magnetic field (the predominant 

field) in the top coil system is opposite to that in the lower coil system at any instant. 

Not shown in Figure 2 are two rectangular coils at the ends of the exposure system 

which bend the magnetic field lines and direct many of the field lines from the upper to 

lower set of coils at one end, and from the lower to . upper set of coils at the opposite 

end (the direction of the field lines reverse as the direction of the current reverses). 

The regions between the coils are labelled Bay 1 [top (T) or bottom (B)], Bay 2, etc., 

with Bay 1 being at the northern-most location. Mice and rats housed in plastic 

enclosures are introduced into the magnetic field on racks that roll into the individual 

bays. The mice occupy the upper levels in each coil system and the rats occupy the 

lower levels (Fig. 2). Present during the measurements were James Gauger, Louise 

Brousek, and Tim Johnson from IITRI and Martin Misakian from NIST. Louise 

Brousek participated in performing the measurements and Tim Johnson set the magnetic 

field levels in the different rooms according to an exposure scheme described below. 

60-Hz Magnetic Field UniformitY and Magnitude 

Table 1 shows the expected field levels in the different exposure systems according to 

room number and exposure scheme. The symbol I refers to an exposure system that is 

operated in an intermittent mode normally. During most of the measurements reported 

below, the field was left on continuously. · 

Table 1. Exposure Schemes 

Exposure 

Scheme 

Room 

1 2 3 4 5 

A 1mT 1 mT(I) 0.2mT sham 2 J!T 

B 21-lT 1 mT 1 mT(I) 0.2mT sham 

2 

151 60-Hz Magnetic Fields, NTP TR 488 

c sham 2 llT 1mT 1 mT(I) 0.2mT 

D 0.2mT sham 2 llT 1 mT 1 mT(I) 

E 1 mT(I) 0.2mT sham 2 llT 1mT 

In order to characterize the field uniformity, measurements were made of the axial 

magnetic field at representative points in four exposure systems (Rooms 1, 3-5) when 

exposure scheme D was activated and in the remaining exposure system (Room 2) when 

exposure scheme A was activated. The measurements were made using a NIST 

magnetic field meter with an approximately 7 em diameter probe. Thus, the 

measurements are average field values over the cross sectional area of the probe. In the 

top of each coil system, , 18 measurements were made near a perimeter line which 

encloses the area occupied by the mice, and along a center line in the same area. The 

center of the probe was about 7 em above the floor of the animal enclosure in each case. 

The uniformity was characterized by noting the measurements with the greatest negative 

and positive deviations, in percent, from the central value (points along center line in 

Bays 3 and 4). Thirty-six measurements were made in the lower coil system at the levels 

of the mice and rats--again along perimeter lines and center lines. P_erforming a larger 

number of measurements in the lower coil system did not make a significant difference 

in the largest deviations from the central values. ­

The magnitude of the central magnetic field was measured in each exposure system and 

compared with the expected value for all the exposure schemes. For the sham condition, 

the largest resultant magnetic field observed in all the bays (top and bottom) is reported. 

The resultant magnetic field, R, is given by 

where B1, Bl> and B 3 are three spatially orthogonal field components. The resultant field 

values were obtained with a three-axis field meter. The uncertainty in the NIST 

measurements with the 7 em probe is estimated to be less than ±2%. The three-axis 

meter has been compared with resultant field measurements obtained with the NIST 

field meter and agreement within 0.01 I,.LT has been observed for measurements in the 

0.1 to 0.2 J.lT range. The magnitude and uniformity results are given below according to 

room number. 

3 

152 60-Hz Magnetic Fields, NTP TR 488 

Room 1 

Uniformity. All magnetic field measurements in the top and bottom coil systems were 

within -4.8% to 0.3% (T) and -5.3% to 0.2% (B), respectively of their central values. 

Magnitude. The departure of the central magnetic field from the expected field value is 

listed in Table 2 for the different exposure schemes. 

Table 2. Departure of central field from expected value--Room 1 

Departure (%)--Top/Bottom Expected Value (Exp. Scheme) 

1.8/1.8 1.0 mT (A) 

s.9n.9 2.0 J.LT (B) 

largest R ~ 0.05 1-LT sham (C) 

5.0/6.4 0.2 mT (D) 

3.1/3.0 1.0 mT(I) (E) 

Room 2 

Uniformity. All magnetic field measurements in the top and bottom coil systems were 

within -4.3% to 0.0% (T) and -3.4% to 1.6% (B), respectively of their central values. 

Magnitude. The departure of the central magnetic field from the expected field value is 

listed in Table 3 for the different exposure schemes. 

Table 3. Departure of central field from expected value--Room 2 

Departure (%)--Top/Bottom Expected Value (Exp. Scheme) 

1.8/1.6 1.0 mT(I) (A) 

3.6/3.1 1.0 mT (B) 

6.2/10.9 2.0 J.LT (C) 

largest R ~ 0.04 J.LT sham (D) 

5.1/4.8 0.2 mT (E) 

4 

153 60-Hz Magnetic Fields, NTP TR 488 

Room3 

Uniformity. All magnetic field measurements in the top and bottom coil systems were 

within -5.2% to 0.2% (T) and -2.0% to 1.6% (B), respectively of their central values. 

Magnitude. The departure of the central magnetic field from the expected field value is 

listed in Table 4 for the different exposure schemes. 

Table 4. Departure of central field from expected value--Room 3 

Departure (%)--Top/Bottom Expected Value (Exp. Scheme) 

4.5/5.1 0.2 mT (A) 

2.7/2.8 1.0 mT(I) (B) 

3.6/3.7 1.0 mT (C) 

9.3/8.5 2.0 llT (D) 

largest R ~ 0.04 llT 0.2 mT (E) 

Room 4 

Uniformity. All magnetic field measurements in the top and bottom coil systems were 

within -4.7% to 0.1% (T) and -4.1% to 0.8% (B), respectively of their central values. 

Magnitude. The departure of the central magnetic field from the expected field value is 

listed in Table 5 for the different exposure schemes. 

Table 5. Departure of central field from expected value--Room 4 

Departure (%)--Top/Bottom Expected Value (Exp. Scheme) 

largest R ~ 0.04 llT sham (A) 

4.6/5.3 0.2 mT (B) 

2.9/2.7 1.0 mT(I) (C) 

3.3/3.0 1 mT (D) 

9.0/8.0 2 llT (E) 

5 

154 60-Hz Magnetic Fields, NTP TR 488 

RoomS 

Unifonnity. All magnetic field measurements in the top and bottom coil systems were 

within -4.8% to 0.3% (T) and -3.6% to 1.0% (B), respectively of their central values. 

Magnitude. The departure of the central magnetic field from the expected field value is 

listed in Table 6 for the different exposure schemes. 

Table 6. Departure of central field from expected value--Room 5 

Departure (%)--Top/Bottom Expected Value (Exp. Scheme) 

8.7/10.2 2.0 1-1T (A) 

largest R ~ 0.04 1-1T sham (B) 

5.1/4.8 0.2 mT (C) 

2.0/2.6 1 mT(I) (D) 

3.4/3.5 1 mT (E) 

The data in Tables 2-6 indicate that with one exception, i.e., at the 2 1-1T level, the 

exposure fields are within 10% of the expected values at all the measurement points. 

The deviation from 2 1-1T can reach and exceed 10% by a small amount in the exposure 

systems located in Rooms 2, 3, and 5. The data also show that the sham field levels are 

well under 0.1 1-1T for all exposure schemes (see also Stray Magnetic Fields below). 

Harmonic Content 

The waveform of the 2 1-1T and 0.2 mT magnetic fields were checked for harmonics by 

examining the output signal from the NIST magnetic field meter, using an oscilloscope 

provided by IITRI. For the 1 mT and 1 mT(I) fields, the signal from the magnetic field 

probe, which is proportional to the time-derivative of the magnetic field, was examined 

directly with the oscilloscope. In no case, i.e, for all field levels (excluding sham) in all 

exposure systems and for all exposure schemes, was there discernible distortion of the 

magnetic field waveform or its time-derivative (It should be noted that the timederivative observations are a more sensitive check for harmonic content in the field). 

Prior to the waveform measurements, the linearity of the horizontal axis and the 

frequency response of the oscilloscope were checked by examining the waveforms of a 

square wave on the sweep settings used (or the measurements. Nonlinearities as small 

as 1% of the full sweep would readily be seen with this check, but none were apparent. 

The rise and fall of the square waveform also indicated an adequate frequency response 

for observing 60-Hz waveforms and power frequency harmonics. 

6 

60-Hz Magnetic Fields, NTP TR 488 155 

Stray Magnetic Fields 

The largest resultant magnetic fields in each exposure system under sham conditions 

have been reported above. The effects of stray fields from the energized exposure 

systems on the sham system add up to well under 0.1 !J.T. Another situation for which 

stray fields are considered is during the "off period11 for the 1 mT intermittent exposures. 

Two "worst case" conditions were checked. First, under exposure scheme A, the 

exposure system in Room 2 will have an intermittent 1 mT field. During the off period, 

stray fields can originate from the 1 mT exposure system in adjacent Room 1. 

Contributions from Room 3, whichis not adjacent to Room 2, are not expected to be 

measurable (see Figure 1 and Table 1). The largest resultant magnetic field observed in 

all the bays in Room 2 during the off period was near 0.16 !J.T. Under exposure 

scheme D, similar measurements in Room 5 indicated that the largest resultant magnetic 

field in all the bays was near 0.13 IJ.T. 

60-Hz Electric Fields 

Because voltages will occur between the rectangular loops of wire which produce the 

magnetic fields, electric fields will develop in a direction roughly parallel to the axial 

magnetic fields. Electric field shielding was reportedly provided by the contractor 

responsible for building the exposure systems. Using a NIST-pwned free-body electric 

field meter, measurements were performed in all the bays of each exposure system under 

worst-case conditions, i.e., when the magnetic field was 1 mT. For this condition, the 

current through the magnetic field coils is a maximum and the associated voltage 

between the loops of wire will be the greatest. 

The largest electric fields observed in exposure systems located in Rooms 1,3, and 5, in 

regions that would be occupied by test animals, were less than about 10 V/m. 

In Room 2, electric fields as high as 100 V/m were observed in the bottom sections of 

Bays 1 and 2. Lesser values were observed in the other bays, but their values were not 

recorded. 

In Room 4, electric fields as large as 39 V/m were observed in the bottom sections of 

Bays 3 and 4, and 55 V/m in the bottom section of Bay 5. All other regions had electric 

fields of about 11 V/m or less. 

Whjle the calibration uncertainty associated with the Nis'r free-body meter is estimated 

to be less than ±2%, some additional uncertainty is introduced during measurements 

because the analog display of the field meter is read from a distance, the fields are not 

uniform, and there is some movement of the field meter when the analog display is read. 

Thus, the electric field values reported here should be considered as being approximate. 

7 

156 60-Hz Magnetic Fields, NTP TR 488 

DC Magnetic Field Measurements 

Using a NIST-owned fluxgate magnetometer, measurements were made of the de 

magnetic field component that was parallel to the direction of the ac magnetic field in 

each exposure system, i.e., along the horizontal north-south direction . . The 

measurements were performed in the top and bottom coil systems at the level of the rat 

enclosures in each bay. The results are presented below in Table 7 according to room 

number. 

The calibration uncertainty of the fluxgate magnetometer is estimated to be less 

than ±2%. However, the measurements are sensitive to probe alignment because of the 

nonuniformity of the fields (see below) and the presence of a significant vertical 

magnetic field component. Therefore, the measurement results should be considered 

approximate. 

Table 7. Central de magnetic field values parallel to ac field 

Room Bay Magnetic Field (JJ.T)--Top/Bottom 

1 1 10.5/1.30 

2 14.5n.77 

3 15.6/13.8 

4 15.4/4.8 

5 15.8/11.3 

6 16.9/13.7 

2 1 . 11.3/0.44 

2 11.6/3.18 

3 13.6/3.17 

4 18.4/26.4 

5 21.5/38.5 

6 21.5/29.4 

8 

60-Hz Magnetic Fields, NTP TR 488 157 

3 1 14.2/8.42 

2 14.2/9.67 

3 14.8/13.5 

4 15.8/19.4 

5 16.8/22.8 

6 17.0/23.3 

4 1 20.1!21.3 

2 19.2/15.9 

3 18.3/18.2 

4 16.2/18.8 

5 14.0/9.78 

6 12.0/2.2 

5 1 19.3/25.4 

2 20.7/23.2 

3 18.5/11.5 

4 15.5/-5.5 

5 12.4/-10.7 

6 10.8/-4.5 

The results in the above table indicate a variable de magnetic field aligned with the ac 

field direction. Differences exist between adjacent bays as well as between the top and 

bottom sections of each bay. The minus signs for the field values in Room 5 indicate 

reversals in field direction. When the magnetic field probe was removed from the top 

section of Bay 3 in Room 2, a field reversal was again seen. The perturbations of th~ de 

magnetic field are apparently due to magnetized structural components in the building, 

e.g., magnetized metal beams. A preliminary investigation by James Gauger using a 

hand compass near a wall in Room 5 suggested the presence of a magnetized 

reinforcement bar in the wall which could be responsible for the de field variations. 

Other Items 

Magnetic field Measurements in quarantine and breeding lab Measurements of the 

resultant magnetic field at representative points near floor level and at a height of about 

9 

158 60-Hz Magnetic Fields, NTP TR 488 

1.8 m indicated that the ambient field did not exceed 0.1 !J.T. 

Procedure for energizing magnetic field coils The possibility of transients being produced 

during the "turning on" and "turning off' operations was discussed. Provisions have been 

made in the power supplies to prevent this from happening. For example, a resistor is 

placed across the output of the power supply during the "off' operation, which results in 

a decaying oscillatory current waveform without transients. 

Monitoring "on" condition of magnetic field The magnetic field is continuously monitored. 

Blind operation of experiment Discussions with researchers at IITRI indicate that the 

biological endpoints will not be analyzed under blind conditions. 

Vibrations The racks holding the animal enclosures will not be in mechanical contact 

with the magnetic field coils. No vibrations of the coils could be sensed by touch. 

Mechanical scraping of rack on support structure of exposure facility One rack was used to 

support the magnetic field probes in the different bays of each exposure system. 

Occasionally, the top of the rack would scrape against part of the support frame for the 

water supply. It's not clear whether repeated scraping against the support frame could 

lead to mechanical failure of the frame. 

10 

II 

0 

0 91 

u 

; 

0 0 

60-HZ Magnetic Fields, NTP TR 488
 159 

FIGURE F1 
North~ 

z 

y 

160 60-HZ Magnetic Fields, NTP TR 488 

FIGURE F2 

Two sets of rectangular coils of exposure systems with axes parallel to 

north-south direction. 
161 

APPENDIX G 

INGREDIENTS, NUTRIENT COMPOSITION, 

AND CONTAMINANT LEVELS 

IN NTP-2000 RAT AND MOUSE RATION 

TABLE G1 

TABLE G2 

TABLE G3 

TABLE G4 

Ingredients of NTP-2000 Rat and Mouse Ration ............................ 

Vitamins and Minerals in NTP-2000 Rat and Mouse Ration .................... 

Nutrient Composition of NTP-2000 Rat and Mouse Ration ..................... 

Contaminant Levels in NTP-2000 Rat and Mouse Ration ...................... 

162 

162 

163 

164 
162 60-Hz Magnetic Fields, NTP TR 488 

TABLE G1 

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 perservatives) 3.0 

Soy oil (without perservatives) 3.0 

Dried brewer’s yeast 1.0 

Calcium carbonate (USP) 0.9 

Vitamin premixa 

Mineral premixb 

0.5 

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 

TABLE G2 

Vitamins and Minerals in NTP-2000 Rat and Mouse Rationa 

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 bisulfate 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 

B12 

Pyridoxine 

52 μg 

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 
60-Hz Magnetic Fields, NTP TR 488 163 

TABLE G3 

Nutrient Composition of NTP-2000 Rat and Mouse Ration 

Mean ± Standard 

Nutrient Deviation Range Number of Samples 

Protein (% by weight) 14.16 ± 0.91 12.9 — 16.2 17 

Crude fat (% by weight) 8.34 ± 0.40 7.50 — 8.80 17 

Crude fiber (% by weight) 9.38 ± 0.73 7.80 — 10.3 17 

Ash (% by weight) 4.95 ± 0.17 4.53 — 5.30 17 

Amino Acids (% total diet) 

Arginine 0.752 ± 0.05 0.69 — 0.80 4 

Cystine 0.22 ± 0.01 0.22 — 0.24 4 

Glycine 0.712 ± 0.02 0.69 — 0.74 4 

Histidine 0.345 ± 0.01 0.33 — 0.35 4 

Isoleucine 0.548 ± 0.03 0.51 — 0.59 4 

Leucine 1.107 ± 0.03 1.07 — 1.13 4 

Lysine 0.728 ± 0.06 0.65 — 0.79 4 

Methionine 0.425 ± 0.03 0.40 — 0.46 4 

Phenylalanine 0.625 ± 0.02 0.60 — 0.64 4 

Threonine 0.542 ± 0.03 0.52 — 0.59 4 

Tryptophan 0.132 ± 0.01 0.12 — 0.15 4 

Tyrosine 0.430 ± 0.02 0.40 — 0.46 4 

Valine 0.648 ± 0.04 0.61 — 0.69 4 

Essential Fatty Acids (% of total diet) 

Linoleic 3.95 ± 0.41 3.59 — 4.54 4 

Linolenic 0.295 ± 0.06 0.21 — 0.35 4 

Vitamins 

Vitamin A (IU/kg) 6,106 ± 1,800 3,060 — 9,460 18 

Vitamin D (IU/kg) 1,000a 

"-Tocopherol (ppm) 84.06 ± 15.25 62.2 — 105.0 5 

Thiamine (ppm) 10.52 ± 2.07 7.30 — 15.0 18 

Riboflavin (ppm) 5.9 ± 1.46 4.20 — 7.70 4 

Niacin (ppm) 75.22 ± 2.55 72.8 — 78.8 4 

Pantothenic acid (ppm) 25.02 ± 3.38 21.4 — 29.1 4 

Pyridoxine (ppm) 10.65 ± 2.29 6.9 — 12.4 5 

Folic acid (ppm) 1.70 ± 0.41 1.46 — 2.32 4 

Biotin (ppm) 0.394 ± 0.21 0.277 — 0.704 4 

Vitamin B (ppb) 108.6 ± 70.4 47.4 — 174.0 4 12 

Choline (ppm) 3,000 ± 216 2,700 — 3,200 4 

Minerals 

Calcium (%) 0.94 ± 0.06 0.84 — 1.02 17 

Phosphorus (%) 0.58 ± 0.03 0.50 — 0.64 17 

Potassium (%) 0.667 ± 0.03 0.629 — 0.691 4 

Chloride (%) 0.352 ± 0.04 0.300 — 0.392 4 

Sodium (%) 0.196 ± 0.02 0.160 — 0.212 4 

Magnesium (%) 0.198 ± 0.01 0.185 — 0.213 4 

Sulfur (%) 0.174 ± 0.02 0.153 — 0.205 4 

Iron (ppm) 156.5 ± 16.1 135.0 — 172.0 4 

Manganese (ppm) 52.20 ± 4.70 46.2 — 56.0 4 

Zinc (ppm) 51.15 ± 5.24 45.0 — 57.5 4 

Copper (ppm) 6.345 ± 0.92 5.38 — 7.59 4 

Iodine (ppm) 0.546 ± 0.021 0.39 — 0.84 4 

Chromium (ppm) 0.85 ± 0.77 0.33 — 2.0 4 

Cobalt (ppm) 0.65 ± 0.90 0.20 — 2.0 4 

a From formulation 

 

164 60-Hz Magnetic Fields, NTP TR 488 

TABLE G4 

Contaminant Levels in NTP-2000 Rat and Mouse Rationa 

Mean ± Standard 

Deviationb Range Number of Samples 

Contaminants 

Arsenic (ppm) 0.28 ± 0.09 0.1 — 0.4 16 

Cadmium (ppm) 0.05 ± 0.01 0.04 — 0.07 16 

Lead (ppm) 0.20 ± 0.10 0.06 — 0.4 16 

Mercury (ppm) <0.02 16 

Selenium (ppm) 0.22 ± 0.11 0.10 — 0.50 16 

Aflatoxins (ppm) <5.00 16 

Nitrate nitrogen (ppm)c 8.49 ± 4.59 2.30 — 17.7 16 

Nitrite nitrogen (ppm)c 1.56 ± 1.27 0.30 — 4.00 16 

BHA (ppm)d 1.30 ± 1.33 0.05 — 5.0 16 

BHT (ppm)d 1.05 ± 1.18 0.0 — 5.00 16 

Aerobic plate count (CFU/g) 193,429 ± 293,221 10 — 1,000,000 16 

Coliform (MPN/g) 40 ± 104 0 — 420 16 

Escherichia coli (MPN/g) <10 16 

Salmonella (MPN/g) Negative 16 

Total nitrosoamines (ppb)e 6.64 ± 2.63 3.20 — 11.20 16 e N-Nitrosodimethylamine (ppb) 4.58 ± 2.06 1.20 — 9.40 16 e N-Nitrosopyrrolidine (ppb) 2.06 ± 0.90 1.00 — 3.60 16 

Pesticides (ppm) 

"-BHC <0.01 16 

$-BHC <0.02 16 

(-BHC <0.01 16 

*-BHC <0.01 16 

Heptachlor <0.01 16 

Aldrin <0.01 16 

Heptachlor epoxide <0.01 16 

DDE <0.01 16 

DDD <0.01 16 

DDT <0.01 16 

HCB <0.01 16 

Mirex <0.01 16 

Methoxychlor <0.05 16 

Dieldrin <0.01 16 

Endrin <0.01 16 

Telodrin <0.01 16 

Chlordane <0.05 16 

Toxaphene <0.10 16 

Estimated PCBs <0.20 16 

Ronnel <0.01 16 

Ethion <0.02 16 

Trithion <0.05 16 

Diazinon <0.10 16 

Methyl parathion <0.02 16 

Ethyl parathion <0.02 16 

Malathion 0.12 ± 0.14 0.02 — 0.60 16 

Endosulfan I <0.01 16 

Endosulfan II <0.01 16 

Endosulfan sulfate <0.03 16 

a 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.
 

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. 

c 
165 

APPENDIX H 

SENTINEL ANIMAL PROGRAM 

METHODS .............................................................. 

RESULTS ............................................................... 

166 

168 
 

 


 

166 60-Hz Magnetic Fields, NTP TR 488 

SENTINEL ANIMAL PROGRAM
 

METHODS 

Rodents used in the Carcinogenesis Program of the National Toxicology Program are produced in optimally 

clean facilities to eliminate potential pathogens that may affect study results. The Sentinel Animal Program 

is part of the periodic monitoring of animal health that occurs during the toxicologic evaluation of chemical 

compounds. Under this program, the disease state of the rodents is monitored via serology on sera from 

extra (sentinel) animals in the study rooms. These animals and the study animals are subject to identical 

environmental conditions. The sentinel animals come from the same production source and weanling 

groups as the animals used for the studies of chemical compounds. 

Serum samples were collected from randomly selected rats and mice during the 2-year studies. Blood from 

each animal was collected and allowed to clot, and the serum was separated. The samples were processed 

appropriately and sent to Microbiological Associates, Inc. (Bethesda, MD), for determination of antibody 

titers. The laboratory serology methods and viral agents for which testing was performed are tabulated 

below; the times at which blood was collected during the studies are also listed. 

Method and Test Time of Analysis 

RATS 

ELISA 

Mycoplasma arthritidis 

Mycoplasma pulmonis 

PVM (pneumonia virus of mice) 

RCV/SDA (rat coronavirus/ 

sialodacryoadenitis virus)

 Sendai 

Study termination 

Study termination 

1 week or 1 month; 7, 13, or 19 months; study termination 

1 week or 1 month; 7, 13, or 19 months; study termination 

1 week or 1 month; 7, 13, or 19 months; study termination 

Immunofluorescence Assay

 PVM 13 months

 RCV/SDA 13 months 

Hemagglutination Inhibition

 H-1 (Toolan’s H-1 virus) 

KRV (Kilham rat virus) 

1 week or 1 month; 7, 13, or 19 months; study termination 

1 week or 1 month; 7, 13, or 19 months; study termination 
 

 

60-Hz Magnetic Fields, NTP TR 488 167 

MICE 

ELISA

 Ectromelia virus Study initiation or 3 weeks; 6 or 7 months; 12 or 

13 months; 18 or 19 months; study termination

 EDIM (epizootic diarrhea of infant mice) Study initiation or 3 weeks; 6 or 7 months; 12 or 

13 months; 18 or 19 months; study termination

 GDVII (mouse encephalomyelitis virus) Study initiation or 3 weeks; 6 or 7 months; 12 or 

13 months; 18 or 19 months; study termination

 LCM (lymphocytic choriomeningitis virus) Study initiation or 3 weeks; 6 or 7 months; 12 or 

13 months; 18 or 19 months; study termination

 Mouse adenoma virus-FL Study initiation or 3 weeks; 6 or 7 months; 12 or 

13 months; 18 or 19 months; study termination

 MHV (mouse hepatitis virus) Study initiation or 3 weeks; 6 or 7 months; 12 or 

13 months; 18 or 19 months; study termination 

M. arthritidis Study termination 

M. pulmonis Study termination

 PVM Study initiation or 3 weeks; 6 or 7 months; 12 or 

13 months; 18 or 19 months; study termination

 Reovirus 3 Study initiation or 3 weeks; 6 or 7 months; 12 or 

13 months; 18 or 19 months; study termination

 Sendai Study initiation or 3 weeks; 6 or 7 months; 12 or 

13 months; 18 or 19 months; study termination 

Immunofluorescence Assay

 GDVII 12 or 13 months; 18 or 19 months

 LCM 12 or 13 months; 18 or 19 months; study termination

 Mouse adenoma virus-FL 12 or 13 months

 MCMV (mouse cytomegalovirus) Study termination

 MHV Study termination

 Parvovirus Study termination

 Polyoma virus Study termination

 Reovirus 3 6 or 7 months 

Hemagglutination Inhibition

 K (papovavirus) Study initiation or 3 weeks; 6 or 7 months; 12 or 

13 months; 18 or 19 months; study termination

 MVM (minute virus of mice) Study initiation or 3 weeks; 6 or 7 months; 12 or 

13 months; 18 or 19 months; study termination

 Polyoma virus Study initiation or 3 weeks; 6 or 7 months; 12 or 

13 months; 18 or 19 months; study termination 
168 60-Hz Magnetic Fields, NTP TR 488 

RESULTS 

At the end of the studies, two rats and one mouse had positive titers for M. arthritidis, and one mouse had a 

positive titer for MHV. Further evaluation of samples positive for M. arthritidis by immunoblot and 

Western blot procedures indicated that the positive titers may have been due to cross reaction with 

antibodies of nonpathogenic Mycoplasma or other agents. Only sporadic samples were positive and there 

were no clinical findings or histopathologic findings of M. arthritidis infection in animals with positive 

titers. Further evaluation of the sample positive for MHV by Western blot analysis was negative for 

specific antibodies. Accordingly, M. arthritidis- and MHV-positive titers were considered to be false 

positives.