National Cancer Institute 

CARCINOGENESIS 

Technical Report Series 

No. 38 

1978 

BIOASSAY OF 

AROCLOR® 1254 

FOR POSSIBLE CARCINOGENICITY 

CAS No. 27323-18-8 

NCI-CG-TR-38 

U.S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE 

Public Health Service 

National Institutes of Health 

BIOASSAY OF



AROCLOR® 1254 
 

FOR POSSIBLE CARCINOGENICITY 
 

Carcinogenesis Testing Program 

Division of Cancer Cause and Prevention 

National Cancer Institute 
 

National Institutes of Health 
 

Bethesda, Maryland 20014 
 

U.S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE 
 

Public Health Service 
 

National Institutes of Health 
 

DHEW Publication No. (NIH) 78-838 
 

BIOASSAY OF AROCLOR® 1254 
 

FOR POSSIBLE 
 

CARCINOGENICITY 
 

Carcinogenesis Testing Program 
 

Division of Cancer Cause and 
 

Prevention 
 

National Cancer Institute 
 

National Institutes of 
 

Health 
 

CONTRIBUTORS: This report presents the results of the bioassay of
 


Aroclor® 1254 for possible carcinogenicity, conducted for the 
 

Carcinogenesis Testing Program, Division of Cancer Cause and
 


Prevention, National Cancer Institute (NCI), Bethesda, Maryland. 
 

The bioassay was conducted by Stanford Research Institute, Menlo 
 

Park, California, initially under direct contract to NCI and 
 

currently under a subcontract to Tracor Jitco, Inc., prime 
 

contractor for the NCI Carcinogenesis Testing Program. 
 

The experimental design and doses were determined by Drs. R. R.



Bates1

'2, D. C. L. Jones3, D. P. Sasmore3, G. W. Newell3, and R. 
 

M. Elashoff4

, and Mr. W. E. Davis3. The principal investigator



was Dr. D. C. L. Jones; the technical supervisor of animal



treatment, observation, and data handling was Mr. W. E. Davis; 
 

necropsy and tissue fixation were supervised by Dr. D. P.
 


Sasmore. 
 

Histopathologic examinations were performed by Dr. H. Elster5

 and 
 

the diagnoses included in this report represent his
 


interpretation. Neoplasms and compound-related hyperplastic
 


lesions were reviewed by Drs. W. M. Busey6

 and J. F. Hardisty6, 
 

who also prepared the interpretive pathology summary included in



this report. 
 

Animal pathology tables and survival tables were compiled at EG&G
 


Mason Research Institute7

. The statistical analyses were
 


performed by Dr. J. R. Joiner8

, using methods selected for the 
 

bioassay program by Dr. J. J. Gart9

. Chemicals used in this



iii


bioassay were analyzed at Stanford Research Institute, and the 
 

analytical results were reviewed by Dr. C. W. Jameson8

. 
 

This report was prepared at Tracer Jitco8

 under the direction of



NCI. Those responsible for the report at Tracer Jitco were Dr.
 


Marshall Steinberg, Director of the Bioassay Program; Drs. J. F.
 


Robens and R. W. Fogleman, toxicologists; Dr. R. L. Schueler,



pathologist; Ms. L. A. Waitz and Mr. W. D. Reichardt, bioscience 
 

writers; and Dr. E. W. Gunberg, technical editor, assisted by Ms.
 


Y. E. Presley. 
 

The statistical analysis was reviewed by members of the 
 

Mathematical Statistics and Applied Mathematics Section of NCI9

: 
 

Dr. John J. Gart, Mr. Jun-mo Nam, Dr. Hugh M. Pettigrew, and Dr.
 


Robert E. Tarone. 
 

The following other scientists at the National Cancer Institute 
 

were responsible for evaluating the bioassay experiment, 
 

interpreting the results, and reporting the findings: 
 

Dr. Kenneth C. Chu 
 

Dr. Cipriano Cueto, Jr. 
 

Dr. J. Fielding Douglas 
 

Dr. Dawn G. Goodman 
 

Dr. Richard A. Griesemer 
 

Mr. Harry A. Milman 
 

Dr. Thomas W. Orme 
 

Dr. Robert A. Squire10 
 

Dr. Jerrold M. Ward 
 

1 Carcinogenesis Testing Program, Division of Cancer Cause and 
 

Prevention, National Cancer Institute, National Institutes 
 

of Health, Bethesda, Maryland. 
 

2 Now with the Office of the Commissioner, Food and 
 

Drug Administration, Rockville, Maryland. 
 

3 Stanford Research Institute, Menlo Park, California. 
 

iv 
 
4 Department of Biomathematics, Center for the Health Sciences, 
 

University of California, Los Angeles, California. 
 

5 Department of Pathology, David M. Brotman Memorial 
 

Hospital, 3828 Hughes Avenue, Culver City, California. 
 

6 Experimental Pathology Laboratories, Inc., P.O. Box 474, 
 

Herndon, Virginia. 
 

7 EG&G Mason Research Institute, 1530 East Jefferson Street, 
 

Rockville, Maryland. 
 

8 Tracor Jitco, Inc., 1776 East Jefferson Street, 
 

Rockville, Maryland. 
 

9 Mathematical Statistics and Applied Mathematics Section, 
 

Biometry Branch, Field Studies and Statistics, Division of 
 

Cancer Cause and Prevention, National Cancer Institute, 
 

National Institutes of Health, Bethesda, Maryland. 
 

10 Now with the Division of Comparative Medicine, Johns Hopkins 
 

University, School of Medicine, Traylor Building, Baltimore, 
 

Maryland. 
 

v



SUMMARY



A bioassay of Aroclor® 1254 for possible carcinogenicity was



conducted by administering the test chemical in feed to Fischer
 


344 rats. 
 

Groups of 24 rats of each sex were administered Aroclor® 1254 at
 


one of three doses, either 25, 50, or 100 ppm, for 104-105 weeks. 
 

Matched controls consisted of groups of 24 untreated rats of each
 


sex. All surviving rats were killed at 104-105 weeks. 
 

Mean body weights of males and females receiving mid and high



doses and females receiving low doses of the chemical were
 


consistently below those of the corresponding controls, beginning
 


at about week 10 of the study. The decrease in survival among 
 

males, but not among females, showed a significant dose-related
 


trend. Adequate numbers of animals of both sexes survived for



meaningful statistical analyses of the incidences of tumors. 
 

The combined incidences of lymphomas and leukemias showed a



significant dose-related trend in males (controls 3/24, low-dose
 


2/24, mid-dose 5/24, high-dose 9/24, P = 0.009). However, the



direct comparisons of each dosed group with those of the matched



controls were not statistically significant, and the tumors 
 

cannot clearly be related to administration of with Aroclor®



1254. 
 

Hepatocellular adenomas and carcinomas were found in the dosed 
 

groups, but not in the controls (males: mid-dose 1/24, high-dose



3/24; females: mid-dose 1/24, high-dose 2/24). Additionally, a



high incidence of nonneoplastic hyperplastic nodules was noted in



the dosed animals (males: controls 0/24, low-dose 5/24, mid-dose
 


8/24, high-dose 12/24; females: controls 0/23, low-dose 6/24,



mid-dose 9/22, high-dose 17/24). Although the incidences of
 


tumors were not significant, the occurrence of the hyperplastic



nodules appeared to be related to administration of the chemical. 
 

vii 
 
In the stomach, jejunum, or cecum, adenocarcinomas were observed
 


in two dosed males and in two dosed females as well as a 
 

carcinoma in one dosed male. None of these lesions was found in
 


control animals in this study. Historical incidences of these 
 

tumors at this laboratory (6/600 males [1%], 2/600 females [0.3%]
 


suggest that the lesions — although not statistically significant 
 

— may be related to the administration of Aroclor® 1254. 
 

It is concluded that under the conditions of this bioassay, 
 

Aroclor® 1254 was not carcinogenic in Fischer 344 rats; however,
 


a high incidence of hepatocellular proliferative lesions in both 
 

male and female rats was related to administration of the
 


chemical. In addition, the carcinomas of the gastrointestinal 
 

tract may be associated with administration of Aroclor® 1254 in
 


both males and females. 
 

viii 
 
TABLE OF CONTENTS



Page



I. Introduction............................................... 1 
 

II. Materials and Methods...................................... 3 
 

A. Chemical............................................. 3 
 

B. Dietary Preparation.................................. 3 
 

C. Animals.............................................. 4 
 

D. Animal Maintenance................................... 5 
 

E. Subchronic Studies................................... 6 
 

F. Design of Chronic Studies............................ 7 
 

G. Clinical and Pathologic Examinations................. 7 
 

H. Data Recording and Statistical Analyses.............. 9 
 

III. Results - Rats............................................ 15 
 

A. Body Weights and Clinical Signs ..................... 15 
 

B. Survival............................................. 15 
 

C. Pathology ........................................... 18 
 

D. Statistical Analyses of Results ..................... 21 
 

IV. Discussion................................................ 23 
 

V. Bibliography.............................................. 27 
 

APPENDIXES



Appendix A Summary of the Incidence of Neoplasms in 
 

Rats Fed Aroclor® 1254 in the Diet ............... 31 
 

Table Al Summary of the Incidence of Neoplasms in 
 

Male Rats Fed Aroclor® 1254 in the Diet .......... 33 
 

Table A2 Summary of the Incidence of Neoplasms in 
 

Female Rats Fed Aroclor® 1254 in the Diet ........ 37 
 

Appendix B Summary of the Incidence of Nonneoplastic 
 

Lesions in Rats Fed Aroclor® 1254 in the Diet .... 41 
 

Table B1 	 Summary of the Incidence of Nonneoplastic 
 

Lesions in Male Rats Fed Aroclor® 1254 
 

in the Diet ...................................... 43 
 

ix 
 
 

 

 

Page 

Table B2 Summary of the Incidence of Nonneoplastic 

Lesions in Female Rats Fed Aroclor® 1254 

in the Diet...................................... 47 

Appendix C Analyses of the Incidence of Primary Tumors 

in Rats Fed Aroclor® 1254 in the Diet............ 51 

Table C1 Analyses of the Incidence of Primary Tumors 

in Male Rats Fed Aroclor® 1254 in the Diet....... 53 

Table C2 Analyses of the Incidence of Primary Tumors 

in Female Rats Fed Aroclor® 1254 in the Diet..... 57 

TABLES 

Table 1 Design of Aroclor® 1254 Chronic Feeding 

Studies in Rats.................................. 8 

FIGURES 

Figure 1 Growth Curves for Rats Fed Aroclor® 1254 

in the Diet...................................... 16 

Figure 2 Survival Curves for Rats Fed Aroclor® 1254 

in the Diet...................................... 17 

x


 

I. INTRODUCTION



Aroclor® (CAS 27323-18-8; NCI C02664) is the registered trademark 
 

of the Monsanto Chemical Company for their polychlorinated 
 

biphenyls (PCBs). PCBs were developed in 1929 primarily for use
 


as heat transfer fluids and dielectrics (insulators). Aroclor®
 


1254, a biphenyl containing approximately 54% chlorine, is a



nonflammable heat transfer agent which functions in the range of 
 

250-360°C (Hubbard, 1964; Poffenberger and Hubbard, 1965). 
 

PCBs have been used in transformers and capacitors; as industrial
 


fluids in hydraulic, gas turbine, and vacuum pumps; as lubricants
 


and plasticizers (for flame retardation); and as additives in 
 

surface coatings, inks, papers, adhesives, sealants, pesticides,
 


and dyes for carbonless duplicating paper (Hubbard, 1964; 
 

Broadhurst, 1972). These compounds tend to accummulate in the 
 

biosphere (Finklea et al., 1972). Because of direct and indirect



human and animal exposure, food contamination, and environmental
 


pollution from many of these uses, the marketing of PCBs has been
 


markedly curtailed in recent years (EPA, 1977). 
 

This bioassay of Aroclor® 1254 was conducted as a part of a 
 

larger study designed to assess the combined effects of a group
 


of known or suspected carcinogens. Only the results of the study
 


of the administration of Aroclor® 1254 are reported herein. 
 

1



II. MATERIALS AND METHODS



A. Chemical



Aroclor® 1254 was obtained in a single batch (Lot No. KB01-604)
 


from the Monsanto Chemical Company, St. Louis, Missouri. The
 


identity and relative purity of the test chemical were confirmed



at Stanford Research Institute. Elemental analyses (C, H, Cl)



indicated 54.67% chlorine. Gas-liquid chromatography and mass 
 

spectroscopy showed that the Aroclor® 1254 contained at least 18



isomers of polychlorinated biphenyls ranging from 4 to 7 chlorine 
 

atoms per molecule. Identity was confirmed by nuclear magnetic
 


resonance, infrared, and ultraviolet spectra, which were in
 


agreement with the structure. No attempt was made to identify or 
 

quantitate impurities. 
 

The chemical was stored at room temperature in 1-gallon amber
 


glass jars. 
 

B. Dietary Preparation
 


All diets were formulated every 2 weeks using Low Fat Lab Chow®
 


(Ralston Purina Co., St. Louis, Mo.). A stock diet was first pre­


pared by hand mixing a weighed amount of the Aroclor® 1254 with
 


corn oil (Staley Manufacturing Co., Orange, Calif.) and adding 
 

this mixture to a small amount of feed which was also mixed by



3


hand. More corn oil and feed were then added to give a final 
 

concentration of 3,000 ppm Aroclor® 1254 and 3% corn oil and then 
 

machine mixed in a Hobart blender for 30 minutes. Each stock diet
 


was analyzed for content of Aroclor® 1254 by a method involving
 


extraction, Florisil® chromatography, and quantitation by gas-
 

liquid chromatography. Concentrations of 3,000 ppm ± 10% were 
 

considered acceptable for use in preparing the test diets. 
 

Aroclor® 1254 at 3,000 ppm in the stock diet was found to be 
 

stable when held in rat feeders at room temperature for a 2-week 
 

period. 
 

To obtain test diets having appropriate concentrations of 
 

Aroclor® 1254, the stock diet was diluted, as required, with



control diet containing 3% corn oil and mixed in a Hobart
 


blender. The stock and test diets were stored at room temperature
 


in covered plastic containers. 
 

C. Animals



Male and female Fischer 344 rats, obtained through contracts of
 


the Division of Cancer Treatment, National Cancer Institute, were 
 

used in these bioassays. The rats were obtained from Simonsen



Laboratory, Gilroy, California. On arrival at the laboratory, all 
 

animals were quarantined for 2 weeks as an acclimation period. 
 

Following this period, all males gaining less than 25
 


4


grams, all females gaining less than 15 grams, and all unhealthy
 


animals were culled. The remaining animals were assigned to



cages, one per cage, until each cage contained three animals.
 


Cages were then numbered and assigned to control and treated 
 

groups using a computer-generated randomization table. Rats were
 


ear-clipped for individual identification. 
 

D. Animal Maintenance



All animals were housed in temperature- and humidity-controlled 
 

rooms. The temperature was maintained at 22°C with a range of 21­


24°C, and the relative humidity was maintained at approximately



45%. The room air was changed 10 times per hour and was



maintained under positive pressure to the access halls.
 


Fluorescent lighting provided illumination 12 hours per day. Food



and water were available ad libitum. Drinking water was softened,
 


filtered, sterilized with ultraviolet light, and supplied by
 


means of an automatic watering system. 
 

The rats were housed three per cage in polycarbonate cages
 


equipped with disposable polyester woven filter tops. Autoclaved 
 

hardwood chips (Iso-Dri® , Becton, Dickinson, and Carworth,
 


Warrensburg, N.Y.) were used as bedding. The cages were changed, 
 

washed, and provided with fresh bedding twice per week. Filter
 


tops were replaced once per month. 
 

5


Rats fed Aroclor® 1254 were housed in the same room as rats
 


treated with aflatoxin B1 (CAS 1162-65-8), lead (II) acetate (CAS 
 

301-04-2), hexachlorophene (CAS 70-30-4), or dieldrin (CAS
 


60-57-1) in the feed. 
 

E. Subchronic Studies



Subchronic feeding studies were conducted with male and female



Fischer 344 rats to estimate the maximum tolerated dose of
 


Aroclor® 1254, on the basis of which low, mid, and high 
 

concentrations (hereinafter referred to as "low doses", "mid
 


doses", and "high doses") were determined for administration in
 


the chronic studies. In the subchronic studies, Aroclor® 1254 was 
 

added to feed in concentrations of 25, 50, 100, 200, or 400 ppm. 
 

Treated and control groups each consisted of 15 male and 15
 


female rats. The chemical was provided in feed to the treated 
 

groups for 8 weeks. 
 

The animals receiving 400 ppm were inactive, had occasional



diarrhea and tremors, and failed to gain weight. At this dose 
 

4/15 males and 1/15 females died. Enlarged livers were observed



on gross examination, and histologically atypical hyperplasia was 
 

observed. At 200 ppm, body weights for both males and females 
 

were approximately 70% of those of the controls, and mild hepato­


cellular pleomorphism was seen histologically in the livers.



6


Rats treated with 25 ppm Aroclor® 1254 had enlarged livers, but
 


no evidence of histologic abnormalities. Weight gain in all 
 

animals treated at doses lower than 200 ppm was comparable to
 


that in controls, and there was no mortality below 400 ppm. The



low, mid, and high doses for the chronic studies were set at 25, 
 

50, and 100 ppm. 
 

F. Design of Chronic Studies



The design of the chronic studies is shown in table 1. 
 

G. Clinical and Pathologic Examinations



All animals were observed daily for signs of toxicity and
 


palpated for masses at each weighing. Animals were weighed
 


individually every other week for 12 weeks, and once every fourth 
 

week for the remainder of the study. Animals that were moribund 
 

at the time of clinical examination were killed and necropsied. 
 

The pathologic evaluation consisted of gross examination of major 
 

organs and tissues from killed animals and from animals found
 


dead. The following tissues were routinely examined micro­


scopically from both treated and control animals: lungs and 
 

bronchi, spleen, liver, testes, pituitary, kidney, and brain. In
 


addition, sections of stomach, urinary bladder, thyroid, uterus,



and ovary were examined in a majority of the controls; these
 


7


Sex and 

Treatment 

Initial 

No. of 

Aroclor® 1254 

in Dietb Treatedc

Animalsa Group (ppm) (weeks) (weeks) 

Males

Matched-Control 24 0 105 

Low-Dose 24 25 105 

Mid-Dose 24 50 105 

High-Dose 24 100 105 

Females 

Matched-Control 24 0 105 

Low-Dose 24 25 104-105 

Mid-Dose 24 50 104-105 

High-Dose 24 100 105 

Table 1. Design of Aroclor® 1254 Chronic Feeding Studies in Rats 
 

Time on Study 
 

Untreated



a All animals were 53 ± 2 days of age when placed on study. 
 

b All diets contained 3% corn oil. 
 

c A11 animals were started on study within 2 days of each other. 
 

8


tissues were taken from treated rats only if a lesion was found 
 

at necropsy. Occasionally, additional tissues were examined
 


microscopically. Gross lesions from all animals were also
 


examined microscopically. The different tissues were preserved in



10% buffered formalin, embedded in paraffin, sectioned, and
 


stained with hematoxylin and eosin. Special staining techniques
 


were utilized when indicated for more definitive diagnosis. 
 

A few of the tissues selected by design from some animals were
 


not examined, particularly from those animals that died early. 
 

Thus, the number of animals from which particular organs or 
 

tissues were microscopically examined varies, and does not
 


necessarily represent the number of animals that were placed on
 


study in each group. 
 

H. Data Recording and Statistical Analyses



Pertinent data on this experiment have been recorded in an auto­


matic data processing system, the Carcinogenesis Bioassay Data 
 

System (Linhart et al., 1974). The data elements include descrip­


tive information on the chemicals, animals, experimental design,
 


clinical observations, survival, body weight, and individual
 


pathologic results, as recommended by the International Union
 


Against Cancer (Berenblum, 1969). Data tables were generated for 
 

verification of data transcription and for statistical review. 
 

9 
 
These data were analyzed using the statistical techniques 
 

described in this section. Those analyses of the experimental 
 

results that bear on the possibility of carcinogenicity are
 


discussed in the statistical narrative sections. 
 

Probabilities of survival were estimated by the product-limit 
 

procedure of Kaplan and Meier (1958) and are presented in this 
 

report in the form of graphs. Animals were statistically censored 
 

as of the time that they died of other than natural causes or 
 

were found to be missing; animals dying from natural causes were
 


not statistically censored. Statistical analyses for a possible
 


dose-related effect on survival used the method of Cox (1972) for
 


testing two groups for equality and Tarone's (1975) extensions of 
 

Cox's methods for testing for a dose-related trend. One-tailed P



values have been reported for all tests except the departure from 
 

linearity test, which is only reported when its two-tailed P
 


value is less than 0.05. 
 

The incidence of neoplastic or nonneoplastic lesions has been
 


given as the ratio of the number of animals bearing such lesions
 


at a specific anatomic site (numerator) to the number of animals
 


necropsied (denominator). 
 

The purpose of the statistical analyses of tumor incidence is to 
 

determine whether animals receiving the test chemical developed a
 


10


significantly higher proportion of tumors than did the control 
 

animals. As a part of these analyses, the one-tailed Fisher exact
 


test (Cox, 1970) was used to compare the tumor incidence of a



control group with that of a group of treated animals at each 
 

dose level. When results for a number of treated groups (k) are 
 

compared simultaneously with those for a control group, a



correction to ensure an overall significance level of 0.05 may be
 


made. The Bonferroni inequality (Miller, 1966) requires that the 
 

P value for any comparison be less than or equal to 0.05/k. In
 


cases where this correction was used, it is discussed in the
 


narrative section. It is not, however, presented in the tables,
 


where the Fisher exact P values are shown. 
 

The Cochran-Armitage test for linear trend in proportions, with



continuity correction (Armitage, 1971), was also used. Under the
 


assumption of a linear trend, this test determines if the slope 
 

of the dose-response curve is different from zero at the one-
 

tailed 0.05 level of significance. Unless otherwise noted, the
 


direction of the significant trend is a positive dose relation­


ship. This method also provides a two-tailed test of departure



from linear trend. 
 

A time-adjusted analysis was applied when numerous early deaths



resulted from causes that were not associated with the formation 
 

of tumors. In this analysis, deaths that occurred before the



11


first tumor was observed were excluded by basing the statistical 
 

tests on animals that survived at least 52 weeks, unless a tumor
 


was found at the anatomic site of interest before week 52. When



such an early tumor was found, comparisons were based exclusively



on animals that survived at least as long as the animal in which 
 

the first tumor was found. Once this reduced set of data was
 


obtained, the standard procedures for analyses of the incidence 
 

of tumors (Fisher exact tests, Cochran-Armitage tests, etc.) were 
 

followed. 
 

When appropriate, life-table methods were used to analyze the 
 

incidence of tumors. Curves of the proportions surviving without
 


an observed tumor were computed as in Saffiotti et al. (1972). 
 

The week during which an animal died naturally or was sacrificed 
 

was entered as the time point of tumor observation. Cox's methods 
 

of comparing these curves were used for two groups; Tarone's 
 

extension to testing for linear trend was used for three groups. 
 

The statistical tests for the incidence of tumors which used
 


life-table methods were one-tailed and, unless otherwise noted, 
 

in the direction of a positive dose relationship. Significant 
 

departures from linearity (P < 0.05, two-tailed test) were also 
 

noted. 
 

The approximate 95 percent confidence interval for the relative
 


risk of each treated group compared to its control was calculated
 


12


from the exact interval on the odds ratio (Gart, 1971). The



relative risk is defined as pt/pc where pt is the true binomial
 


probability of the incidence of a specific type of tumor in a 
 

treated group of animals and pc is the true probability of the 
 

spontaneous incidence of the same type of tumor in a control



group. The hypothesis of equality between the true proportion of
 


a specific tumor in a treated group and the proportion in a 
 

control group corresponds to a relative risk of unity. Values in



excess of unity represent the condition of a larger proportion in



the treated group than in the control. 
 

The lower and upper limits of the confidence interval of the



relative risk have been included in the tables of statistical
 


analyses. The interpretation of the limits is that in
 


approximately 95% of a large number of identical experiments, the 
 

true ratio of the risk in a treated group of animals to that in a
 


control group would be within the interval calculated from the
 


experiment. When the lower limit of the confidence interval is 
 

greater than one, it can be inferred that a statistically
 


significant result (P < 0.025 one-tailed test when the control
 


incidence is not zero, P < 0.050 when the control incidence is 
 

zero) has occurred. When the lower limit is less than unity, but 
 

the upper limit is greater than unity, the lower limit indicates



the absence of a significant result while the upper limit
 


13


indicates that there is a theoretical possibility of the 
 

induction of tumors by the test chemical, which could not be
 


detected under the conditions of this test. 
 

14


III. RESULTS



A. Body Weights and Clinical Signs



Beginning at about week 10 for the high-dose groups and about
 


week 20 for the mid-dose groups, mean body weights of both male 
 

and female rats fed Aroclor® 1254 at the doses used in this



bioassay were lower than those of the controls (figure 1). Mean
 


body weights of low-dose males appeared comparable to those of
 


controls throughout the study, while mean body weights of low-
 

dose females were lower during the second year of the study. At 
 

week 30, an intercurrent respiratory infection in the colony



caused weight loss, but no deaths; animals recovered within 30
 


days without treatment for the infection. 
 

Clinical signs associated with administration of Aroclor® 1254



included alopecia, amber-colored urine, facial edema, exoph­


thalmos, and cyanosis. These signs were apparent among the high-
 

dose groups beginning at week 72 and among the mid-dose groups at
 


week 104 of the study. 
 

B. Survival



The Kaplan and Meier curves estimating the probabilities of



survival for male and female rats fed Aroclor® 1254 in the diet 
 

15


~.---------------------------------------------------------~ 

0 ij~Co@8§80 0 8 8 0 0 0 ~ 8 8 ft ij 0 0 0 8 0 0 

300- e 0 ° 0 0 0 0 0 0 ~ 0 0 0 

0 0 0 6. 6. 6. 6. 6. 6. 6. 6. 0 0 0 0 0 0 6. 6. 6. ~ 6. 6. 6. 6. ~ 6. 6. 6. 6. 6. 6. X 0 

~ ~e~ w ~ 6. 6. 

6. 

~ 

> 200 ~ ' + 

0 

0 

CD 8 ..... . 

z MALE RATS 

ct 

w 0 MATCHED CONTROL ~ 0 LOW DOSE 

100 0 MID DOSE 

6. HIGH DOSE 

0+-----~----r----,r----.-----.----~----------~----,-----~--~ 0 10 20 :W 40 50 60 70 80 90 100 110 

TIME ON STUDY IWEEKSI 

~~------------------------------------------------------------~ 

300 

~ 

~ 

X 

w 

~ 0 0 0 0 0 0 0 

0 0 0 ° ~ 0 0 0 0 0 0 0 0 0 

> 200 

0 e 8 g o o o o o o 

0 

s g 8 8 8 g 

CD 6. 6. 6. 6. 6. 6. 6. 6. 6. 6. 6. 6. 6. 6. 6. 

z 

ct 

w 

~ 

FEMALE RATS 

0MATCHEDCONTROL 

0 LOW DOSE 

0 MID DOSE 

6. HIGH DOSE 

0+-----~----r----,r----.-----.----~-----.-----r----~----,---~ 0 ~ ~ ~ k ~ ~ k ~ ~ 100 110 

TIME ON STUDY (WEEKS) 

Figure 1. Growth Curves for Rats Fed Aroclor® 1254 in the Diet 

16 
 
1.00 .. .. .. . ... 

~ ~, 

0.90 ¢.. ·-~ -·- · ~-- -- 6, ................. -6-..-·-:-'"'! (>.. 

b ·-¢-·t" ... : 6.--o 0.110 <>-· h_ .. ; 

~ 

... 0.70 /:r·b:-1 ~ b_ .. :(r._ > 

> ~ &.. a: 0.60 :::l -: 00 VI }:, .. , ... 

0 0.50 >-

... l::.t:> ::; 

iii 0.40 ~ 

m 

0 MALE RATS a: 

Q. 0.30 

0 MATCHED CONTROL 

OLOW OOSE 

0.20 0 MIDOOSE 

/:>HIGH OOSE 

0.10 

0.00 

0 15 30 45 60 15 90 \05 1~0 

TIME ON STUDY IWEEKSI 

1.00 .... .. . . ·:.. · ___ . :..·.·:_ :::.-:.. . 

0,90 

0.80 

... 0.70 

~ 

> 

> a: 0.80 :::l 

VI 

... 

0 0.50 >-

.... 

::; 

iii 0.40 ~ 

m 

0 FEMALE RATS a: 

Q. 0.30 

0 MATCHED CONTROL 

0 LOWDDSE 

0.20 0 MIDDDSE 

/:> HIGH DOSE 

0.10 

0.00 90 105 120 0 15 30 45 60 7S 

TIME ON STUDY IWEEKSI 

Figure 2. Survival Curves for Rats Fed Aroclor® 1254 in the Diet 

17 
 
at the doses used in this study, together with those of the 
 

controls, are shown in figure 2. 
 

For males, the result of the Tarone test for positive dose-
 

related trend in mortality over the period is significant (P <
 


0.001); 92% of the control, 83% of the low-dose, 58% of the mid-
 

dose, and 46% of the high-dose rats survived to the end of the 
 

study. Among females, the Tarone test showed a probability level
 


greater than 0.05. In females, 67% of the control, 79% of the
 


low-dose, 83% of the mid-dose, and 71% of the high-dose rats
 


survived to termination of the study. Sufficient numbers of rats
 


of both sexes were available for meaningful statistical analyses 
 

of the incidences of late-developing tumors. 
 

C. Pathology



Histopathologic findings on neoplasms in rats are summarized in
 


Appendix A, tables Al and A2; findings on nonneoplastic lesions
 


are summarized in Appendix B, tables B1 and B2. 
 

A variety of neoplastic processes were observed in both the 
 

control and treated rats, and, with the exception of the liver,
 


the incidences of these neoplasms were comparable in the control
 


and treated groups. Interstitial-cell tumors of the testes were
 


present in the majority of control and treated males. The next
 


most frequently observed neoplasm was leukemia of either the



18


MALES FEMALES 

Low 

Dose

Mid 

Dose 

High 

Dose 

Low 

Dose 

Mid High 

Dose Dose 

Number of 

Animals 

Necropsied (24) (24) (24) (24) (22) (24)

Nodular 

Hyperplasia 5 8 12 6 9 17 

Adenoma, NOS* 0 0 1 0 1 2 

Hepatocellular 

Carcinoma 0 1 2 0 0 0 

Total Incidence 5 9 15 6 10 19 

granulocytic or lymphocytic type, and it involved multiple
 


organs. The incidence of this neoplastic process was comparable



in the control and treated groups. The following neoplasms were



also present in some control and treated rats but without
 


compound association: squamous-cell carcinomas of the skin,
 


alveolar/bronchiolar adenomas of the lung, and uterine
 


endometrial stromal polyps. 
 

No proliferative lesions of the hepatocytes were found in the



control animals in the study. The incidence of these prolifera­


tive lesions among treated animals was as follows: 
 

*Not otherwise specified 
 

The areas of nodular hyperplasia appeared to be microscopically



similar to what is currently termed "focal areas of cellular



19


alteration" (Squire and Levitt, 1975). Neither this lesion nor 
 

any hepatocellular adenomas or carcinomas were diagnosed in the



controls. The hepatocellular carcinomas were characterized
 


microscopically by large foci of proliferating hepatocytes
 


involving several lobules. These hepatocytes were bizarre in



appearance, sometimes containing two or more nuclei. The
 


sinusoidal architecture was lost, and frequently mitotic figures 
 

were present. These neoplasms compressed the surrounding normal
 


liver tissue, and the cell plates usually were three to five 
 

cells in thickness. The hepatocellular adenomas were character­


ized by large foci involving several lobules of swollen, severely 
 

vacuolated hepatocytes still maintaining the general sinusoidal 
 

architecture of the liver. In general, the foci of nodular



hyperplasia involved two or more hepatic lobules and contained 
 

hepatocytes whose tinctorial properties were distinctly different
 


from those of the surrounding liver tissue. Occasionally, these



foci would contain severely vacuolated hepatocytes, and in some



instances, there were small foci of basophilic hepatocytes. 
 

The results of the histopathologic examination indicate that the



administration of Aroclor® 1254 at the three doses used in this 
 

study had an effect with respect to proliferative lesions of the 
 

liver and gastrointestinal tract. There were three hepatocellular
 


carcinomas in male rats and a dose-related increase in
 


20


 

nodular hyperplasia in both the male and female animals. There 
 

was one carcinoma and four adenocarcinomas in the gastrointes­


tinal tract of treated rats. These neoplastic lesions are seen 
 

only sporadically and at a low incidence in the Fischer 344 rat;
 


in this study no lesions of these types were diagnosed in either
 


the male or female controls. 
 

D. Statistical Analyses of Results



Tables C1 and C2 in Appendix C contain the statistical analyses 
 

of the incidences of those primary tumors that occurred in at 
 

least two animals in one group and with an incidence of at least 
 

5% of one or more treated groups. 
 

In male rats, the results of the Cochran-Armitage test for 
 

positive dose-related trend in the incidences of leukemia and of



combined leukemia and lymphoma are significant (P = 0.022 and P =
 


0.009, respectively). The corresponding results of the Fisher
 


exact test, however, are not significant in any treated group
 


when compared with the controls. There is no other incidence of
 


tumors at any specific site in either sex which is statistically 
 

significant. A significant Cochran-Armitage trend in the negative



direction is observed in the incidence of interstitial-cell tumor 
 

of the testis, where the incidence in the controls exceeds those 
 

in the mid- and high-dose groups. 
 

21


In each of the 95% confidence intervals of relative risk, shown 
 

in the tables, the value of one is included; this indicates the
 


absence of significant positive results. It should also be noted



that each of the intervals has an upper limit greater than one,
 


indicating the theoretical possibility of the induction of tumors 
 

by Aroclor® 1254, which could not be detected under the
 


conditions of this test. 
 

22


IV. DISCUSSION



At the doses used in this bioassay, Aroclor® 1254 was toxic to 
 

both male and female Fischer 344 rats, as shown by the dose-
 

related depression of mean body weights and the clinical signs
 


which occurred during the second year. Mean body weights of mid- 
 

and high-dose males and of all treated females were consistently



lower than those of the corresponding controls after the initial



growth phase. An intercurrent respiratory infection at week 30 
 

resulted in temporary weight loss, but no deaths, in all groups 
 

including the controls; the animals later recovered without
 


treatment. Clinical signs including alopecia, amber-colored
 


urine, facial edema, exophthalmos, and cyanosis occurred in the
 


high-dose groups beginning at week 72 and in the mid-dose groups
 


at week 104. Survival among males, but not among females, showed 
 

a significant dose-related trend. Adequate numbers of animals of 
 

both sexes survived for meaningful statistical analyses of the 
 

incidences of tumors. 
 

The combined incidences of lymphoma and leukemia in males were



significant (controls 3/24, low-dose 2/24, mid-dose 5/24, high-


dose 9/24, P = 0.009), using the Cochran-Armitage test for
 


positive dose-related trend, but not in females (controls 4/24, 
 

low-dose 6/24, mid-dose 6/24, high-dose 6/24). Since the results
 


of the Fisher exact test for increased incidence were not
 


23


significant for any of these groups, the occurrence of these



lesions cannot clearly be related to the administration of



Aroclor® 1254. 
 

Hepatocellular changes including hyperplastic nodules, adenomas,
 


and carcinomas were found in treated animals, but none of these 
 

lesions were found in control animals in this study. Hepato­


cellular carcinomas were observed in one mid-dose and two high-
 

dose males, and hepatocellular adenomas were observed in one
 


high-dose male, one mid-dose female, and two high-dose females. 
 

Nodular hyperplasia was diagnosed with a dose-related frequency



in the low-, mid-, and high-dose male and female rats. Although
 


the incidences of the tumors were not significant, the occurrence 
 

of these proliferative lesions appeared to be related to
 


treatment. 
 

In the stomach, jejunum, or cecum, adenocarcinomas were observed 
 

in two treated males and in two treated females as well as a 
 

carcinoma in one treated male. None of these lesions was found in 
 

control animals in this study, suggesting that the lesions —
 


although not statistically significant — may be related to the 
 

administration of Aroclor® 1254. 
 

The toxicity of polychlorinated biphenyls (PCBs) has been 
 

reviewed by several groups, including the Environmental
 


24


Protection Agency (1976), National Research Council (1976), Panel 
 

on Hazardous Trace Substances (1972), and International Agency
 


for Research on Cancer (1974). Kimbrough et al. (1972) 
 

demonstrated hepatic adenofibrosis in male and female Sherman



rats fed Aroclor® 1254 at up to 500 ppm for 8 months. A similar 
 

PCB, Kanechlor® 500, fed for 12 months to male Wistar rats,
 


induced nodular hyperplasia at doses of 100-1,000 ppm; at 1,000
 


ppm, cholangiofibrosis also was induced (Ito et al., 1974). 
 

Keplinger et al. (1971; see also EPA Criteria Document PCBs,



1976) fed Charles River rats up to 100 ppm Aroclor® 1254 for 24
 


months and reported originally that there was no significant
 


increase in hepatic tumors in this study; re-evaluation of the



liver slides, however, indicated a significant incidence of



nodular hyperplasia in treated rats, compared with controls. Ito
 


et al. (1973) observed nodular hyperplasia and well-
 

differentiated hepatocellular carcinoma in male strain dd mice
 


fed 500 ppm Kanechlor® 500 for 8 months, and Kimbrough and Linder



(1974) observed adenofibrosis and hepatomas in BALB/cJ mice fed 
 

300 ppm ® Aroclor 1254 for 11 months. 
 

In a study of a closely related PCB, Kimbrough et al. (1975) 
 

observed hepatocellular carcinomas in female Sherman rats fed 100
 


ppm Aroclor® 1260 for 21 months. 
 

It is concluded that under the conditions of this bioassay,
 


25


Aroclor® 1254 was not carcinogenic in Fischer 344 rats; however,
 


a high incidence of hepatocellular proliferative lesions in both 
 

male and female rats was related to treatment. In addition, the
 


carcinomas of the gastrointestinal tract may be associated with
 


treatment in both males and females. 
 

26


 

V. BIBLIOGRAPHY 
 

Armitage, P., Statistical Methods in Medical Research, John Wiley 
 

& Sons, Inc., New York, 1971, pp. 362-365. 
 

Berenblum, I. , ed. , Carcinogenicity Testing: A Report of the 
 

Panel on Carcinogenicity of the Cancer Research Commission 
 

of the UICC, Vol. 2.. International Union Against Cancer,
 


Geneva, 1969. 
 

Broadhurst, M. G. , Use and replaceability of polychlorinated 
 

biphenyls. Environ. Health Perspect. 2;81-102, 1972. 
 

Cox, D. R. , Regression models and life tables, J. R. Statist.
 


Soc. B34(2):187-220. 1972. 
 

Cox, D. R., Analysis of Binary Data, Methuen & Co., Ltd., London,
 


1970, pp. 48-52. 
 

Environmental Protection Agency, Polychlorinated Biphenyls 
 

(PCBs). Toxic Substances Control. Federal Register 42(100),
 


26564-26577, 1977. 
 

Environmental Protection Agency, Criteria Document PCBs, U. S.
 


Government Printing Office, Washington, D. C., 440/9-76-021. 
 

Finklea, J., Priester, L. E., Creason, J. P., Hauser, T., 
 

Hinners, T., and Hammer, D. I., Polychlorinated biphenyl 
 

Residues in human plasma expose a major urban pollution 
 

problem. AJPH 62(5);645-651. 1972. 
 

Gart, J. J., The comparison of proportions: a review of
 


significance tests, confidence limits and adjustments for
 


stratification. Rev. Int. Stat. Inst. 39(2);148-169. 1971. 
 

Hubbard, H. L., Chlorinated biphenyl and related compounds. Kirk-


Othmer Encyclopedia of Chemical Technology. Vol. _5, 
 

Interscience Publishers, New York, 1964, pp. 289-297. 
 

International Agency for Research on Cancer, Some anti-thyroid 
 

and related substances, nitrofurans and industrial
 


chemicals. IARC Monographs on the Evaluation of the



Carcinogenic Risk of Chemicals to Man; Vol. _7, World Health 
 

Organization, Geneva, 1974, pp. 261-289. 
 

27 
 
Ito, N. , Nagasaki, H., Makiura, S., and Aral, M.,
 


Histopathological studies on liver tumorigenesis in rats
 


treated with polychlorinated biphenyls. Gann 65 (6):545-549, 
 

1974. 
 

Ito, N. , Nagasaki, H. , Arai, M., Makiura, S., Sugihara, S., and
 


Hirao, R. , Histopathologic studies on liver tumorigenesis 
 

induced in mice by technical polychlorinated biphenyls and 
 

its promoting effect on liver tumors induced by benzene
 


hexachloride. J. Natl. Cancer Inst. 51(5); 1637-1642, 1973. 
 

Kaplan, E. L. and Meier, P. , Nonparametric estimation from 
 

incomplete observations. J. Amer. Statist. Assoc. 53:457­


481, 1958. 
 

Keplinger, M. L. , Fancher, 0. E. , and Calandra, J. C.,



Toxicologic studies with polychlorinated biphenyls.
 


Toxicol. Appl. Pharmacol. 19(2);402-403, 1971. 
 

Kimbrough, R. D., Squire, R. A., Linder, R. E., Strandberg, J. D. 
 

, Montali, R. J. , and Burse, V. W., Induction of liver
 


tumors in Sherman strain female rats by polychlorinated
 


biphenyl Aroclor 1260. J. National Canc. Inst. 55(6); 1453­


1456, 1975. 
 

Kimbrough, R. D. and Linder, R. E., Induction of adenofibrosis



and hepatomas of the liver in BALB/cJ mice by 
 

polychlorinated biphenyls (Aroclor 1254). J. Natl. Cancer
 


Inst. 53(2);547-552. 1974. 
 

Kimbrough, R. D. , Linder, R. E. , and Gaines, T. B.,
 


Morphological changes in livers of rats fed polychlorinated
 


biphenyls. Arch. Environ. Health 25;354-364. 1972. 
 

Linhart, M. S., Cooper, J. A., Martin, R. L., Page, N. P., and 
 

Peters, J. A., Carcinogenesis bioassay data system. Comp.



and Biomed. Res. 7;230-248, 1974. 
 

Miller, R. G. , Jr., Simultaneous Statistical Inference, McGraw-


Hill Book Co., New York, 1966, pp. 6-10. 
 

National Research Council, Report of Organic Contaminants
 


(unpublished), National Research Council, Assembly of Life 
 

Sciences, Washington, D.C., 1976. 
 

28 
 
Panel on Hazardous Trace Substances, Polychlorinated biophenyls­


environmental impact. Environ. Res. _5:249-362, 1972. 
 

Poffenberger, N. and Hubbard, H. L. , Diphenyl and terphenyls.
 


Kirk-Othmer Encyclopedia of Chemical Technology, Vol. 1



Interscience Publishers, New York, 1965, p. 193. 
 

Saffiotti, U., Montesano, R., Sellakumar, A. R. , Cefis, F. , and



Kaufman, D. G., Respiratory tract carcinogenesis in hamsters
 


induced by different numbers of administrations of benzo(a) 
 

pyrene and ferric oxide. Cancer Res 32:1073-1081, 1972. 
 

Squire, R. A. and Levitt, M. H., Report on a workshop on



classification of specific hepatocellular lesions in rats.



Cancer Res. 35:3214-3223. 1975. 
 

Tarone, R. E., Tests for trend in life table analysis. 
 

Biometrika 62(3):679-682. 1975. 
 

29 
 

APPENDIX A 
 

SUMMARY OF THE INCIDENCE OF NEOPLASMS 
 

IN RATS FED AROCLOR® 1254 IN THE DIET 
 

31 
 

TABLE A1. 


SUMMARY OF THE INCIDENCE OF NEOPLASMS IN MALE 


RATS FED AROCLOR® 1254 IN THE DIET 


=======================~=====~===~===================================~======~================= 

CONTROL LOW DOSE MID DOSE HIGH DOSE 

INI!IALS INITIALLY IN STUDY 24 24 

ANIMALS NECROPSIED 24 24 

ANIMALS EXA!IIN!D HISTOPATHOLOGICALLY 24 24 

INT!GU!IENTARY SYSTEft 

*SKIN (241 (241 (241 (2111 

SQUAMOUS CHL PAPILLOMA 1 (4"1

SQUAMOUS CUt CARCINOMA 1 (4") 

*SUBCUT TISSU.E (24) (24) (24) (24) 

SQU A!IO US C.ELL CARCINO!IA 1 (4"1 1 (4'111 

FIBRO!IA 1 (4'11) 1 (4'111 

!IYXO!IA 1 (4'11) 

RESPiaATORY SYStEM 

fLUNG/BRONCHUS (231 (241 (2 31 (241 


PAPILLO!IA, NOS 1 (4'111 


UUNG (231 (241 (2 31 (241 

CARCINO!IA, Nos. !lET ASTATIC 1 (4"1

ALVEOLAR/BRCNCHIOLAR ADENO!IA 2 (9'111 2 (8") 

HUARTC!IA 1 (4'CI 

H!!IATOPOIETIC SYStE!I 

*!IULTIPLE ORGANS (24) (241 (241 (241 

LY!IPHOCYTIC L.EUKE!IIA 4 (17"1 

GRANULOCYTIC LEUKE!IIA 3 (13") 2 (8") ~ (21'111 4 (171) 

ILY!IPH NODE (31 (3) (II) (51 

!IALIGNANT LY!IPHO!A, NOS 1 (20") 

CIRCULATORY SlST!ft 

__121~-----------------------------------------------------------------------------------------

t NU!IBER OP ANIMALS WITH TISSUE EXAMINED MICROSCOPICALLY 

* NU!IBER OF ANIMALS NECROPSIED 

33 

TABLE A1. MALE RATS: NEOPLASMS (CONTINUED) 


CONTROL LOW DOSE MID DOSE HIGH DOSE 

DIGESriVE SYSTEM 

.SALIVARY GLAND ( 1) (3) 


SARCOMA, NOS 1 (33:l) 


HIVER (24) (24) ( 24) (24) 

P.DENOMA, NCS 1 ( 4") 

HePATOCEllULAR CARCINOMA (4%) 2 (8") 

iSTOIIACH (21) (2) (6) 


ADENOCARCINOMA, NOS 1 (SOli) 


iJEJU NUM ( 1) 

CA!1CINOMA,NOS 1 ( 100") 

ICECU!I ( 1) (4) 


ADENOCAPCINCMA, NOS 1 ( 1 00%) 


URINAI<Y SYS'IEM 

NONL 

ENDOCRINE SYS'IEM 

UITUITAR Y (2 3) (24) (22) (24) 


ADENOMA, NCS 2 (8%) 


HDReNAL ( 1) ( 1) 


PHEOCHP.OMCCYTCMA 1 (, (\ 0%) 


REPROuUCTIVE SYSTEM 

tTESTIS (24) (24) (24) (24) 

INTERSTITIAL-CELL TUMOR 24 (1 00%) 24 (100%) 20 (8 3%) 20 (83%) 

*SCROTUM (24) (24) (24) (24) 


FIB!iOM A 1 ( 4%) 


NERVOUS SYSTEM 

_.!!Q.!!Jl___________________________________________________________________________________ 

t NUMB~R OF ANIMALS WITH TISSUE EXAMINED MICROSCOPICALLY * NU!IBER OF ANIMALS NECROPSIED 

34 

TABLE A1. MALE RATS: NEOPLASMS (CONTINUED) 


CONTROL LOW DOSE MID DOSE HIGH DOSE 

SPECIAL SENSE CRGANS 

NONE 

MUSCULOSKELETAL SYSTEM 

NONE 

ECDY CAVITIES 

*TUNICA VAGINALIS (24) (24) (2 4) (24) 


MESOTHELICMA, MALIGNANT 1 (4 %) 


ALL OTHER SYSTEMS 

NONE 

ANIMAL DISPOSiliON SUMMARY 

ANIIIALS INiliALLY IN STUDY 24 24 24 24 


NATURAL DEATHill 2 3 1 


MORIBUND SACRIFICE 4 7 12 


SCHEDULED SACRIFICE 


ACCIDENTALlY KILLED 


TERIIINAL SACRIFICE 22 20 14 11 


ANIIIAL IIISSING 


!-I!f~QQ~~-A]lQ~IZJQ_!!In!1~-------------------------------------------------------------------· 

t NUMBER OF ANIIIALS WITH TISSUE EXAMINED MICROSCOPICALLY * NUMBER OF ANIMALS NECROPSIED 

35 

TABLE A1. MALE RATS: NEOPLASMS (CONTINUED) 

CONTROL LOW DOSE MID DOSE HIGH DOSE 

TUMOR SUIIIHRY 

TOT~L ANIMALS WITH PRIMARY 

TOTAL PRIMARY TUMORS 

TUMORS* 24 

32 

24 

32 

20 

32 

21 

37 

TOT~L ANIMALS WITH BENIGN 

TOTAL EENIGN TUMORS 

TUMORS 24 

27 

24 

30 

20 

23 

20 

23 

TOTAL ANIMAl" WITH MALIGNANT 

TOTAL MALIGNANT TUMORS 

TUMORS 5 

5 

2 

2 

9 

9 

12 

14 

TOTAl ANIMAl~ WITH SECONDARY 

TOTAL SFCCNCARY TUIIORS 

TUMORSt 1 

1 

TOTAL ANIMAlS WITH TUIIORS 

BENIGN OR MALIGNANT 

TOTAL UNCE~TAIN TUMORS 

UNCERTAINTOTAL ANIMAL" WITH TUMORS 

PRiaARY OR METASTATIC 

TOTAL UNCERTAIN TUMOnS 

UNCERTAIN­

* PRIMARY TUMOES: ALL TUMORS EXCEPT SECONDARY TUMORS 

SECONDARY TUMORS: METASTATIC TUMORS OR TUMORS INVASIVE INTO AN ADJACENT ORGAN 

36 

TABLE A2. 


SUMMARY OF THE INCIDENCE OF NEOPLASMS IN FEMALE 

RATS FED AROCLOR® 12541N THE DIET 

CONTROL LOW DOSE MID DOSE HIGH DOSE 

ANI~ALS INITIAlLY IN STUDY 24 24 24 24 

ANI~ALS NEC~OFSIED 24 24 24 24 

ANI~ALS EXA~INED HISTOPATHOLOGICALLY 24 24 24 24 

INTEGU~ENTA~Y 5YS~E~ 

*SKIN (24) (24) (24) (24) 


SUUAMOUS CELL CARCINOMA 1 (4%) 


*SUBCUT TISSUE (24) (24) (24) (24) 


FIBROMA 1 (4%) 


FIBROSARCOMA 1 (4") 


FIBROUS HJSTIOCYTO~A, MALIGNANT 1 (4") 


LIPOSARCCIIA 1 (4"1 


RESPIRATORY SYSTEM 

HUNG (22) (24) (24) (211) 


ALVEOL ARt BRONCHIOLAR ADENOMA 1 (5%) 1 !4 "I 


HE~ATOPOIETIC SYSTEM 

*MULTIPLE ORGANS (24) (24) (24) (24) 


MALIG.LYMPHC~A, LYMPHOCYTIC TYPE 1 (II") 


LYIIPHOCY~IC LEUKE~IA 1 ( 4 "I 2 ( 8"1 1 !4 "I 


GRANULOCY~IC LEUKEMIA 3 (13") 4 ( 17Ji) 4 ( 17") 4 (17%) 


I SPLEEN ( 191 (241 (241 (221 


GRANULOC n IC LEUKEMIA 1 (4 "I 


ILY~PH NODE (41 (11 (31 ( 1) 

~ALIG.LY~PHO~A, HISTIOCYTIC TYPE 1 ( 100"1 

CIRCULATORY SYSTEM 

_.!!Ql!~-------------------------------------------------------------------------

I NUMBER OP ANIMALS WITH TISSUE EXAMINED MICROSCOPICALLY 

* NUMBER OF ANIMALS NECROPSIED 

37 

TABLE A2. FEMALE RATS: NEOPLASMS (CONTINUED) 


CONTROL LOW DOSE MID DOSE HIGH DOSE 

tiGESTIVE SYSTEM 

ILIVER (2 3) (2<1) (22) (24) 

UNDIFFEREN!IATED CARCINOMA PIETAS 1 (4%) 

ADENOMA, NCS 1 (5%) 2 (8%) 

ISTOPIACH (2 1) (3) ( 1) (6) 

ADENOMA, NCS 1 ( 17%) 

ADENOCARCINCMA, NOS 1 (33%) 1 (1 00%) 

URINARY SYSTEPI 

*GENITOURINARY TRACT (24) (24) (24) (24) 


LIPOMA 1 ( 4%) 


I KIDNEY (23) (24) (2q) (2 3) 


UNDIFFERENTIATED CARCINOMA 1 ( 4%) 


ENDOCRINE SYS!EII 

IPITUITAR Y (23) (22) (2 2) (23) 

ADENOMA, NOS 4 (17 %) 1 (5%) 1 (5 %) 1 (4%) 

REPRODUCTIVE ~YSTEM 

*IIAIIMARY GLAN[ (24) (24) (24) (24) 


ADENOMA, NCS 1 (4%) 


ADENOCARCINCHA, NOS 4 ( 17%) 


I UTERUS ( 1 4) ( 12) ( 1 5) (6) 

ADENOC AP. C I NOll A, NOS 1 ( 8%) 1 ( 17%) 

AUENOCA IN AtENOMATOUS POLYP 1 (17Jr.) 

LJliOIIYOIIA 1 (8%) 

ENDOMETRIAL STROMAL POLYP 2 ( 14 %) 5 ( 4 2%) (3 3%) 3 (50%) 

tOVARY (20) ( 1) ( 3) 


GRANULOSA-CELL TUMOR 1 ( 100%) 


NERVOUS SYSTEM 

__ !Q!~------------------------------------------------------------------------------------------

t NUMBER OF ANIMALS WITH TISSUE EXAMINeD MICROSCOPICALLY 

* NUMBER OF ANIMALS NECROPSIED 

38 

___________________________________________ _ 

TABLE A2. FEMALE RATS: NEOPLASMS (CONTINUED) 

CONTROL LOW DOSE MID DOSE HIGH DOSE 

SPECIAL SENSE ORGANS 

*EYE (24) (24) (24) (24! 


SEBACEOUS ADENOCARCINOMA 1 (4 I) 


~USCULOSKELETAl SYSTEM 

NONE 

BODY CAVITIES 

NONE 

NONE 

ANIMAL DISFOSI!ION SUMMARY 

ANIIIALS INI!IALLY IN STUDY 24 24 24 24 , , , NATURAL DEATHit 

MORIBUND SACRIFICE 7 4 3 7 

SCHEDULED SACRIFICE 

ACCIDENTAllY KILLED 

TERMINAL SACRIFICE 1b 19 2C 17 

ANIIIAL IUSSING 

!..ll£.1..l!DE~LA.l!I.QUU1L!!ill!ll.S 

t NUMBER OF ANIMALS WITH TISSUE EXAMINED MICROSCOPICALLY 

* NUMBER OF ANIMAlS NECROPSIED 

39 

TABLE A2. FEMALE RATS: NEOPLASMS (CONTINUED) 

-----------------------------------------------------------------------------------------------· -·---------------------------------------------------------------------------------------------­

CONTROL LOW DOSE MID DOSE HIGH DOSE 

~~UIIOR SUIIMAEY 

TOTAL ANIMALS WITH PRIMARY TUMORS* 11 18 13 12 

TOTAL PRIIIARY TUMORS 12 24 17 17 

TOTAL ANIMALS WITH BENIGN TUIIORS 7 8 e 7 

TOTAL BENIGN TUIIORS 8 9 8 7 

TOTAL ANIMALS WITH MALIGNANT TUMORS 4 13 e 9 

TOTAL IIALIGNANT TUMORS 4 14 9 10 

TOTAL ANIMALS WITH SECONDARY TUMORS• 1 


TOTAL SECCNDARY TUMORS 1 


TOTAL ANIIIALS WITH TUIIORS UNCERTAIN­


BENIGN OR IIALIGHANT 1 


TOTAL UHCEETAIN TUIIORS 1 


TOTAL ANIIIALS WITH TUIIORS UNCERTAIN­


PRiftARY OR lllTASTATIC 


TOTAL UNClRTAIN TUMORS 


" PRiftARY TUllO liS: ALL TUIIORS EXCEPT SECONDARY TUIIORS # SECONDARY TUIIORS: IIETASTATIC TUftORS OR TUIIORS INVASIVE INTO AN ADJAClNT ORGAN 

40 

APPENDIX B 


SUMMARY OF THE INCIDENCE OF NONNEOPLASTIC LESIONS 


IN RATS FED AROCLOR~ 1254 IN THE DIET 


41 


------------------------------------------------------------------------------------------------- ---------------------------------------------------------------------------------

TABLE 81. 


SUMMARY OF THE INCIDENCE OF NONNEOPLASTIC LESIONS IN MALE 


RATS FED AROCLOR® 12541N THE DIET 


COIIITROL LOW DOSE MID DOSE HIGH DOSE 

ANIIIALS IIIITIALLY IN STUDY 24 24 24 

AIIIIIALS IIECBOPSIEC 24 24 24 

AIII~ALS EXAIIINED HISTOPATHOLOGICALLY 24 24 24 

INTEGUIIENTARY SYS1EM 

*SUBCUT TISSUE (24) (24) (24) (24) 

CYST, NOS 1 (4,;) 

RESPIRATORY SYSTEII 

I TRACHEA (19) (1) 

INFLArii'IATICN, NOS 1 (5,;) 

HUNG/BRONCHUS (23) (24) (23) (24) 

BRONCHIEC'IASIS 1 (4,;) 4 ( 17'1') 7 (30ll) 1 (4'JI,) 

INFLAIIIIATICN, NOS 1 (4'JI,) 

HUNG (23) (24) (23) (24) 

EIIPHYSEIIA, NOS 1 (4'JI,) 

ATELECTASIS 1 (4'11) 2 (9ll) 1 (4'11) 

CONGESTICN, NOS 9 (39%) 12 (50,;) 7 (30ll) 4 (1711) 

INFLAIIIIATICN, NOS 1 (4%) 

ABSCESS, NOS 2 (9'JI,) 2 (8,;) (13%) 2 (8%) -

tS'?LEEN 

COIIGESTIOII, NOS 

FIBROSIS 

HEIIATOPOII!SIS 

(23) 

1 (4%) 

(24) 

2 

1 

(8%) 

(4%) 

(23) 

1 

2 

(4'JI,) 

(9%) 

(24) 

tL'f!IPH NODE 

CONGESTION, NOS 

NECROSIS, NOS 

HYPERPLASIA, NOS 

(3) (3) (4) 

1 

1 

(25%) 

(25'JI,) 

(5) 

(20'JI,) 

____ l!l.SIIQ~I.:m.Sl.li ______________________l_~l~L-------------------------------------· 

t NIJIIBER OF ANIIIALS WITH TISSUE EXAIIINED IIICROSCOPICALLY 

* NIJIIBER OF AIIIIIALS NECROPSIED 

43 

TABLE 81. MALE RATS: NONNEOPLASTIC LESIONS (CONTINUED) 

--------------------------------------------------------------------------· ·------------------------------------------------------------------------------------------------·

CONTROL LOW DOSE MID DOSE HIGH DOSE 

ICELIAC LYMPH HOCE (31 (31 (41 (51 

LYMPHANGIECTASIS 1 ( 20"1 

CIRCULATORY SYSTEM 

NONE 

~IGESTIVE SYSTEM 

ISALlVARY GLAND ( 11 (3) 


INFLAMMATICN, NOS 1 ( 100") 


(24) (24) (24) 

CONGESTION, NOS 

tLIVeli 

18 (15"1 1C (4 2"1 4 ( 11'!;1 

INFLAMMATICN, GRANULOMATOUS 1 ( 4"1 

GRANULOMA, NOS 1 (4"1

NECROSIS, NOS ( 4") 1 (4") 

NECROSIS, FOCAL 2 (8") 

NECROSIS, CENTRAL 1 (4 ,, 1 ( 4") 

HYPERPLASIA, NODULAR 5 {2aJ e (33ll) 12 (50") 

ANGIECTASI5 4 (1HI 2 (8") 

I STOMACH (211 (21 (6) 

Dl VERTICULUM 1 ( 17ll) 

HYPERPLASI1, LYMPHOID 1 (5"1 

I GASTRIC MUCC5 A (211 (21 (61 

CONGESTIO ~, NOS 1 ( 11"1 

HYPERPLASIA, NOS (5 Oll) 2 (33"1 

I COLON ( 1 I (4) 

FIBROSIS 1 (25"1 

PIGMENTATICN, NOS 1 (25l) 

ICECUM (1) (4) 

N.t.CROSIS, NOS 1 (25"1 

URINARY SYS'IH 

IKIDNEY (24) (241 (211) (24) ----~l~1L_MQE_ ___________________________________________l_J8liL______________________ ~--------

t NUMBER OF ANIMALS WITH TISSUE EXAMINED MICROSCOPICALLY 

* NUMoER OF ANIMALS NECROPSIED 

44 

TA.BLE 81. MALE RATS: NONNEOPLASTIC LESIONS (CONTINUED) 


CONTROL LOW DOSE MID DOSE HIGH DOSE 

PY!LONEFH5ITIS, NOS 1 (II") 


SClEROSIS 1 (II") 


EnOCRINE SYSTEM 

IPITUITARY (23) (211) (22) (211) 

CYST, NOS 

CONGESTION, NOS 1 '""> , (511) 2 (8") 1 ( ""> 

fFARATHYROID (3) (,) 


HYPERPLASIA, NOS 1 (33") 


REPRODUCTIVE SYSTEM 

NONE 

NERVOUS SYSTEM 

I BRAIII (23) (211) (211) (24) 


CONGESTION, NOS 1 (4 II) 


EDEMA, NOS 
 1'""l ABSCESS; NOS , ( ""l 

INFARCT, IICS 1 (II"> 1 '""I 

SPECIAL SENSE ORGANS 

NONE 

MUSCULOSKELETAL SYSTEM 

BODr CAVITIES 

*IMGUIIIAL REGION (211) (211) (211) (211) 

H.I!CROSIS, UT 6 (25"1 5 (21"1 3 (13") " (17%) 

ALL OTHER SYS~fMS 

_.l!!l.IIJ__________________________________________________________________ 

I MUftBER or ANiftALS WITH TISSUE EXAftiHED ftiCROSCOPICALLY 

* llllftBER or AIIIULS IIECROPSIED 

45 

TABLE 81. MALE RATS: NONNEOPLASTIC LESIONS (CONTINUED) 

=============~==============~================================================================== 

CONTROL LOW DOSE MID DOSE HIGH DOSE 

SPECIAL MORPHOLOGY SUMMARY 

NONE 

t NUMBER OF ANIMALS WITH TISSUE EXAMINED MICROSCOPICALLY * NUMbER OF ANIMALS NECROPSIED 

46 

------------------------------------------------------------------------------------------------ ---------------------------------------------------------------------

TABLE 82. 

SUMMARY OF THE INCIDENCE OF NONNEOPLASTIC LESIONS H\1 FEMALE 

RATS FED AROCLOR ® 12541N THE DIET 

CONTROL LOW DOSE MID DOSE HIGH DOSE 

ANHALS INITIAlLY IN STUDY 24 24 24 24 


ANIIULS NI!CROFSIED 24 24 24 24 
 ANI~ALS EXAKIN!D HISTOPATHOlOGICALLY 24 24 24 24 


NONE 

RESPI~ATORY SY~TEM 

HUNG/BiiONCHUS (22) (24) (24) (24) 

BllONCHIEC'IASIS 1 (4ll) 1 (4l) 

ABSCESS, NCS 1 (41) 

tLl1NG (22) (24) (24) (24) 

ATELEC'IASIS 3 ( 13l) 3 (13l) 1 (4l) 

COHGESTICN, NOS 8 (36l) 10 (42l) 8 (331) 10 (42l) 

PETECHIA 1 '4l) IHFLA!II!ATICN, NOS 2 (9l) (4l) 1 (4l) 

INFLA!!I!ATICN, INTERSTITIAL (41) 

ABSCESS, NCS 1 (5l) (4l) 1 (41) 1 (4l) 

H!!llTOPOIETIC ~YS'l!!l 

fSFL£EN ( 19) (24) (24) (22) 


CONGESTICN, NOS 3 ( 13l) 


HEKATOFOHSIS 3 '13l) 


ILY !!PH NODE (4) (1) (3) (1) 


LY!IPHANGI!CTASIS 2 (SOl) 


INFLAII!IATICII, NOS 1 (25l) 


CIRCULATORY SYSTEM 

II!YOCARDIU!I (1) ____.unJI1.1!Al1,S;JL_J2a____;....___________________-l..110Qil._____________________ 

I NUI!BER OF ARII!ALS WITH TISSUE EIA!IIRED !IICROSCOPICALLY * NUI!BER OF ANII!llS NECROPSIFD 

47 

TABLE BZ. FEMALE RATS: NONNEOPLASTIC LESIONS (CONTINUED) 


CONTROL LOW DOSE MID DOSE HIGH DOSE 

DIGESTIVE SYSTEM 

HIVER 

CONGESTION, NOS 

INFLAMMATICN, NOS 

INFLAMMATICN, GR~NULCMA'fOUS 

GRANULOMA, NOS 

FIBROSIS 

NECROSIS, FOCH 

HYPERPLASIA, NODULAR 

ANGIECTASIS 

H1MATOPOIESIS 

(23) 

6 

3 

(26") 

( 13%) 

(24) 

6 

2 

1 

1 

6 

2 

1 

(25") 

(8%) 

( 4%) 

( 4'11:) 

(25~) 

(8'11:) 

(4~) 

(22) 

4 

1 

1 

9 

1 

( 18ll) 

(5") 

( 1 4~) 

(5 %) 

(5'11:) 

(41'11:) 

(5~) 

(24) 

1 

17 

1 

( 4%) 

(71:() 

(4%) 

ILIVER/PERlfCRTAL 

INFLAMMATION, NOS 

(2 3) (24) 

2 (8'11:) 

(2 2) (24) 

*BILl:. DUCT 

INFLAMMATICN, NOS 

(24) (24) (24) 

4 (17%) 

(2~) 

I STOMACH 

DIVERTICULUM 

~FIDERMAl INCLUSION 

CONGESTIC~, NOS 

CYST 

(21) (3) 

1 (33'11:) 

( 1) (6) 

2 

1 

1 

( 33%) 

( 17%) 

( 17%) 

IJEJUNU!I 

INFLAMMAliCN, NOS 

( 1) 

1 (HO%) 

( 1) 

I COLON 

INFLAMMATION, NOS 

( 1) ( 1) 

1 ( 100%) 

(1) 

ICECUM 

INFLA!I!IA1ICN, NOS 

( 1) 

1 (1 00%) 

( 1) ( 1) 

OHNARY SYSHII 

*GENITOORINAEY TRACT (24) (24) (24) (24) 

NECROSIS, FAT 1 (4%) 1 ( 4'11:) 1 (4ll) 

HIDNEY (2 3) (24) (24) (23) 

HYDRONEPHRCSIS 1 (!ill) 

CYST, NOS 1 (4%) 1 (4%) 

ENDOChiNE SYSTEM 

IPITUITARY (23) (22) (22) (23) ____fl2IL_!Q§____________________________J_J1J!l_________j_J2!L_ _______________________________ _ 

t NUMBER OF ANIMALS WITH TISSUE EXAMINED MICROSCOPICALLY 

* NUMBER OF ANIMALS NECROPSIED 

48 

TJ\BLE 82. FEMALE RATS: NONNEOPLASTIC LESIONS (CONTINUED) 

CONTROL LOW DOSE MID DOSE HIGH DOSE 

CONGESTIO, NOS 3 ( 14~) 1 (5~) 1 ( 4") 

HEMORRHAGIC CYST 

UDRENAL (2) (4) 


CONGESTION, NOS 1 (50~) 

REPRODUCTIVE SYSTEM 

*IIA!IMARY GLAN[ ( 2 4) (24) (24) (24) 


HYPERPLA ~I A, CYSTIC 1 (4:\) 


*I'AGINA (24) (24) (24) (24) 


INFARCT, NOS 1 (4%) 


I liT EROS ( 14) ( 12) ( 1 5) (6) 


HYDROMETFA 1 (8~) 1 (H) 


PYOMETRA 6 (43~) 1 (8:\) 1 (H) 


IUTE~US/ENDGMETRIU!I (14) ( 12) ( 15) (6) 


INFLAM!IATICN, NOS 1 (8~) 

HYPERPLASIA, NOS 1 (H) 


HYPERPLASIA, CYSTIC 1 (7:11) 4 (27~) 

tOTERUS/M YOMETRIOM (14) ( 12) ( 15) (6) 

INFLAMMATICN, FOCAL 1 ( 17") 

IOVARY/OVIDOC'I ( 14) ( 12) ( 15) (6) 


CYST, NOS 2 ( 14:\) 


!NFLAMMATICN, NOS 1 (7") 


tOVARY (20) (1) (3) 


CYST, NOS 1 (5") 2 (67\{) 


FOLLICULAR CYST, NOS 1 (5") 


PAROVARIAN CYST 1 (5") 


CONGESTION, !lOS 1 (33ll) 


ABSCESS, NOS 1 (5") 


UR'fOUS SYSTEM 

tBilAUl (2 3) (2 3) (2 4) (22) 


CONGESTION, NOS 1 (4") 


SPECIAL SENSE ORGANS 

*EU . (24) (211) (24) (24) 

___J!Jl1Ql!!U!!.!!.L_______________LJ!!!L_______l_jBliL---------------------------­

-' t ll~ftBER OF ANiftALS WITH TISSUE EXAftiiiED MICROSCOPICALLY 

* NUftBER OF ANIMALS NECROPSU:D 

49 

TABLE 82. FEMALE RATS: NONNEOPLASTIC LESIONS (CONTINUED) 


CONTROL LOW DOSE MID DOSE HIGH DOSE 

ftUSCULOSKELETAl SYSTEM 

NONE 

BODY CAVITIES 

*INGUINAL REGION (24) (24) (24) (24) 

LIPOGRANUlC!IA 1 ( 4%) 

ALL OTHER SYSiE!IS 

NONE 

SPFCIAL ftORFHClOGY SUMMARY 

NO LESION ~EPORTED 

I NUMBER Of ANIMALS WITH TISSUE EXAMINED MICROSCOPICALLY 

* NUMBER Of ANIMALS NECROPSIED 

50 
APPENDIX C 
 

ANALYSES OF THE INCIDENCE OF PRIMARY TUMORS IN 
 

RATS FED AROCLOR® 1254 IN THE DIET 
 

51



Matched Low Mid 

Topography: Morphology Control Dose Dose 

Lung: Alveolar/Bronchiolar 

Adenomab 0/24 (0) 0/24 (0) 2/24 (8) 

P Valuesc,d N.S. N.S. N.S. 

Relative Risk (Matched Control)f -- Infinite 

Lower Limit -- 0.305 

Upper Limit -- Infinite 

Weeks to First Observed Tumor -- -- 105 

Hematopoietic System: 

Leukemiab 3/24 (13) 2/24 (8) 5/24 (21) 

P Valuec,d P = 0.022 N.S. N.S. 

Relative Risk (Matched Control)f 0.667 1.667 

Lower Limit 0.060 0.369 

Upper Limit 5.292 9.600 

Weeks to First Observed Tumor 98 78 84 

Table C1. Analyses of the Incidence of Primary Tumors In Male Rats Fed Aroclor® 125

53


Topography: Morphology 

Matched Control Low Dose Mid Dose 

Hematopoietic System: 

Lymphoma or Leukemiab 3/24 (13) 2/24 (8) 5/24 (21) 

P Valuesc,d P = 0.009 N.S. N.S. 

Relative Risk (Matched Control)f 0.667 1.667 

Lower Limit 0.060 0.369 

Upper Limit 5.292 9.600 

Weeks to First Observed Tumor 98 78 84 

Pituitary: Adenoma, NOSb 0/24 (0) 2/24 (8) 0/24 (0) 

P Values c,d N.S. N.S. N.S. 

Relative Risk (Matched Control)f Infinite 

Lower Limit 0.305 Upper Limit Infinite 

Weeks to First Observed Tumor 105 

54



Table C1. Analyses of the Incidence of Primary Tumors in Male Rats Fed Aroclor® 1254 

(continued) 
 

-­ -­ -­ 

-­ -­ 
Topography: Morphology Matched Low Mid 

Control Dose Dose 

Liver: Hepatocellular 

Carcinomab 0/24 (0) 0/24 (0) 1/24 (4) 

P Valuesc,d N.S. N.S. N.S. 

Relative Risk (Matched Control)f -- Infinite 

Lower Limit -- 0.055 

Upper Limit -- Infinite 

Weeks to First Observed Tumor -- -- 105 

Testis: Interstitial-cell 

Tumorb 24/24 (100) 24/24 (100) 20/24 (83) 

P Valuec,d P = 0.013 (N) N.S. N.S. 

Relative Risk (Matched Control)f 0.833 

Lower Limit 0.000 

Upper Limit 1.200 

Weeks to First Observed Tumor 98 78 77 

55



Table C1. Analyses of the Incidence of Primary Tumors in Male Rats Fed Aroclor® 1(continued)



a Treated groups received doses of 25, 50, or 100 ppm. 
 b Number of tumor-bearing animals/number of animals necropsied (percent). 
 
Table C1. Analyses of the Incidence of Primary Tumors in Male Rats Fed Aroclor® 1254 

(continued) ____________________________________________________________________________

c Beneath the incidence of tumors in the control group is the probability level for th

Armitage test when P < 0.05; otherwise, not significant (N.S.) is indicated. Beneatdence of tumors in a treated group is the probability level for the Fisher exact tescomparison of that treated group with the matched-control group when P < 0.05; othersignificant (N.S.) is indicated. 
 

d A negative trend (N) indicates a lower incidence in a treated group than in the conte The probability level for departure from linear trend is given when P < 0.05 for any f The 95% confidence interval of the relative risk between each treated group and the 

matched-control group. 
 

56 
Matched Low Mid 

Topography: Morphology Control Dose Dose 

Hematopoietic System: 

Leukemia b 4/24 (17) 6/24 (25) 6/24 (25) 

P Values c,d N.S. N.S. N.S. 

Relative Risk (Matched Control)f 1.500 1.500. 

Lower Limit 0.411 0.411 Upper Limit 6.316 6.316 

Weeks to First Observed Tumor 81 74 99 

Hematopoietic System: 

Lymphoma or Leukemia b 4/24 (17) 6/24 (25) 6/24 (25) 

P Value c,d N.S. N.S. N.S. 

Relative Risk (Matched Control)f 1.500 1.500 

Lower Limit 0.411 0.411 

Upper Limit 6.316 6.316 

Weeks to First Observed Tumor 81 74 99 

Table C2. Analyses of the Incidence of Primary Tumors in Female Rats Fed Aroclor® 125

57


Matched Low Mid 

Topography: Morphology Control Dose Dose 

Pituitary: Adenoma, NOS b 4/24 (17) 1/24 (4) 1/24 (4) 

P Values c,d N.S. N.S. N.S. 

Relative Risk (Matched Control)f 0.250 0.250 

Lower Limit 0.005 0.005 Upper Limit 2.288 2.288 

Weeks to First Observed Tumor 100 105 105 

Liver: Adenoma, NOSb 0/24 (0) 0/24 (0) 1/24 (4) 

P Valuec,d N.S. N.S. N.S. 

Relative Risk (Matched Control)f -- Infinite 

Lower Limit -- 0.055 

Upper Limit -- Infinite 

Weeks to First Observed Tumor 105 

58



Table C2. Analyses of the Incidence of Primary Tumors in Female Rats Fed Aroclor® 125

(continued) 
 

-- -- 
Matched Low Mid 

Topography: Morphology Control Dose Dose Mammary Gland: 

Adenocarcinoma, NOSb 0/24 (0) 4/24 (17) 0/24 (0) 

P Valuesc,d N.S. N.S. N.S. 

Departure from Linear Trende P = 0.003 

Relative Risk (Matched Control)f Infinite 

Lower Limit 0.961 

Upper Limit Infinite 

Weeks to First Observed Tumor 105 

Mammary Gland: Adenoma or 

Adenocarcinoma, NOS b 1/24 (4) 4/24 (17) 0/24 (0) 

P Valuec,d N.S. N.S. N.S. 

Departure from Linear Trende P = 0.031 

Relative Risk (Matched Control)f 4.000 0.000 

Lower Limit 0.437 0.000 

Upper Limit 187.475 18.289 

Weeks to First Observed Tumor 105 105 -- 

59



Table C2. Analyses of the Incidence of Primary Tumors in Female Rats Fed Aroclor® 12(continued) 
 

-­ 

-­ 

-­ 

-­ -­ 
Matched Low Mid 

Topography: Morphology Control Dose Dose Uterus: Endometrial Stromal Polypb 2/24 (8) 5/24 (21) 5/24 (21) P Valuesc,d N.S. N.S. N.S. 

Relative Risk (Matched Control)f 2.500 2.500 1

Lower Limit 0.459 0.459 0

Upper Limit 24.045 24.045 1

Weeks to First Observed Tumor 105 100 103 

Table C2. Analyses of the Incidence of Primary Tumors in Female Rats Fed Aroclor® 1254 (continued) 
 

60



3

a Treated groups received doses of 25, 50, or 100 ppm. 
 b Number of tumor-bearing animals/number of animals necropsied (percent). 
 

c Beneath the incidence of tumors in the control group is the probability level for the 

Armitage test when P < 0.05; otherwise, not significant (N.S.) is indicated. Beneath incidence of tumors in a treated group is the probability level for the Fisher exact the comparison of that treated group with the matched-control group when P < 0.05; otnot significant (N.S.) is indicated. 
 

d A negative trend (N) indicates a lower incidence in a treated group than in the contr

e The probability level for departure from linear trend is given when P < 0.05 for any 

comparison. 
 

f The 95% confidence interval of the relative risk between each treated group and the 
 

matched-control group. 
 
Review of the Bioassay of Aroclor 1254® for Carcinogenicity 
 

by the Data Evaluation/Risk Assessment Subgroup of the 
 

Clearinghouse on Environmental Carcinogens 
 

November 28, 1977 
 

The Clearinghouse on Environmental Carcinogens was established in



May, 1976 under the authority of the National Cancer Act of 1971 (P.L. 92­


218). The purpose of the Clearinghouse is to advise on the National Cancer
 


Institute's bioassay program to identify and evaluate chemical carcinogens in
 


the environment to which humans may be exposed. The members of the
 


Clearinghouse have been drawn from academia, industry, organized labor, 
 

public interest groups, State health officials, and quasi-public health and 
 

research organizations. Members have been selected on the basis of their
 


experience in carcinogenesis or related fields and, collectively, provide
 


expertise in organic chemistry, biochemistry, biostatistics, toxicology,
 


pathology, and epidemiology. Representatives of various Governmental agencies



participate as ad hoc members. The Data Evaluation/Risk Assessment Subgroup
 


of the Clearinghouse is charged with the responsibility of providing a peer 
 

review of NCI bioassay reports on chemicals studied for carcinogenicity. In
 


this context, below is the edited excerpt from the minutes of the Subgroup's 
 

meeting at which Aroclor 1254 was reviewed. 
 

(Aroclor 1254 was tested in rats as part of another study designed
 


to investigate the combined effects of chemicals.) The primary reviewer



briefly outlined the experimental design and findings. Although statistically 
 

significant increases in the incidence of tumors were not found in the 
 

treated rats, a high incidence of liver hyperplastic nodules was observed in
 


both sexes. 
 

The primary reviewer said that in published rat and mouse studies, 
 

Aroclor was reported to induce liver neoplasms, although in one rat study 
 

only hyperplastic nodules of the liver were found. In regard to the rat 
 

pathology, he said that after the proliferative stimulus is removed, the
 


hyperplastic nodules regress and disappear. Stimuli of such liver nodules act
 


more like tumor promoters than complete carcinogens. Based on reports in the
 


literature, he concluded that Aroclor 1254 could pose a risk to the human 
 

population as a tumor promoter. A lengthy discussion followed as to whether
 


the evidence was adequate to assess Aroclor's tumor promoting potential. 
 

An NCI staff pathologist pointed out that a number of tumors
 


also were found in the gastrointestinal tract of the treated rats. 
 

Although they did not occur in statistically -significant numbers, none
 


was observed among the control
 


61


animals. A discussion ensued as to the appropriateness of combining 
 

tumors when they occur at different sites along the GI tract. 
 

One Subgroup member opined that the study was deficient because of 
 

an inadequate number of animals per group. He suggested that the tumors
 


of questionable significance may have been more meaningful had more 
 

animals been used. 
 

A motion was made that the conclusion stated in the report summary 
 

be accepted with an addition that Aroclor 1254 may act as a tumor



promoter. The motion thus read: It is concluded that, under the
 


conditions of the bioassay, Aroclor 1254 was not carcinogenic in Fischer 
 

344 rats; however, a high incidence of hepatocellular proliferative 
 

lesions in both male and female rats was related to treatment in addition,
 


the carcinomas of the gastrointestinal tract may be associated with 
 

treatment in both males and females. Based on the liver proliferative 
 

lesions in the treated rats and published reports, it is suggested that
 


Aroclor 1254 may be a tumor promoter. The motion was seconded and
 


accepted by Drs. Wogan, Pitot, Roush, Shimkin, Strong, and Weisburger. Mr. 
 

Garfinkel opposed the motion and Dr. Rowe abstained. 
 

* 	 Subsequent to this review, changes may have been made in the bioassay
 


report either as a result of the review or other reasons. Thus,



certain comments and criticisms reflected in the review may no longer 
 

be appropriate. 
 

U.S. GOVERNMENT PRINTING OFFICE: 1978 260-899/3021 1-3 
 62


DHEW Publication No. (NIH) 78438