National Cancer Institute 

CARCINOGENESIS 

Technical Report Series 

No. 46 

1978 

BIOASSAY OF 

ETHIONAMIDE 

FOR POSSIBLE CARCINOGENICITY 

CAS No. 536-33-4 

NCI-CG-TR-46 

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

Public Health Service 

National Institutes of Health 

BIOASSAY OF
 

ETHIONAMIDE
 

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
 

DREW Publication No. (NIH) 78-846
 

BIOASSAY OF
 

ETHIONAMIDE
 

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 ethionamide 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 Southern Research Institute,
 

Birmingham, Alabama, initially under direct contract to NCI and
 

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

contractor for the NCI Carcinogenesis Testing Program.
 

The experimental design and doses were determined by Drs. D. P.
 

Griswoldl, J. D. Prejean^, E. K. Weisburger^, and J. H.
 

Weisburger2>3. Ms. J. Belzer and Mr. I. Brown1 were responsible
 

for the care and feeding of the laboratory animals. Data management and retrieval were performed by Ms. C. A. Dominick.1. Histopathologic examinations were performed by Drs. S. D. Kosanke^ and
 

J. C. Peckham*-, and the diagnoses included in this report
 

represent their interpretation.
 

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

Mason Research Institute^. The statistical analyses were performed by Dr. J. R. Joiner^, using methods selected for the
 

bioassay program by Dr. J. J. Gart^. Chemicals used in this
 

bioassay were analyzed under the direction of Dr. E. Murrill?,
 

and the analytical results were reviewed by Dr. C. W. Jameson-*.
 

This report was prepared at Tracor Jitco^ under the direction of
 

NCI. Those responsible for the report at Tracor Jitco were
 

Dr. Marshall Steinberg, Director of the Bioassay Program; Dr. L.
 

A. Campbell, Deputy Director for Science; Drs. J. F. Robens and
 

C. H. Williams, toxicologists; Dr. R. L. Schueler, pathologist;
 

Dr. G. L. Miller, Ms. L. A. Waitz, and Mr. W. D. Reichardt,
 

iii
 
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 NCI^:
 

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. Squire**
 

Dr. Jerrold M. Ward
 

^-Southern Research Institute, 2000 Ninth Avenue South,
 

Birmingham, Alabama.
 

•^Carcinogenesis Testing Program, Division of Cancer Cause and
 

Prevention, National Cancer Institute, National Institutes of
 

Health, Bethesda, Maryland.
 

with the Naylor Dana Institute for Disease Prevention,
 

American Health Foundation, Hammond House Road, Valhalla,
 

New York.
 

Mason Research Institute, 1530 East Jefferson Street,
 

Rockville, Maryland
 

^Tracor Jitco, Inc., 1776 East Jefferson Street, Rockville,
 

Maryland.
 

iv
 
^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.
 

^Midwest Research Institute, 425 Volker Boulevard, Kansas City,
 

Missouri.
 

%ow with the Division of Comparative Medicine, Johns Hopkins
 

University, School of Medicine, Traylor Building, Baltimore,
 

Maryland.
 

SUMMARY
 

A bioassay of the chemotherapeutic drug ethionamide for possible
 

carcinogenicity was conducted by administering the test chemical
 

in feed to Fischer 344 rats and B6C3F1 mice.
 

Groups of 35 rats and 34 or 35 mice of each sex were administered
 

ethionamide at one of the following doses, either 1,500 or 3,000
 

ppm for the rats and either 1,000 or 2,000 ppm for the mice. The
 

animals were treated 5 days per week for 78 weeks, then observed
 

for an additional 25 or 26 weeks. Matched controls consisted of
 

groups of 15 untreated rats and 15 untreated mice of each sex.
 

All surviving animals were killed at 103 or 104 weeks.
 

Mean body weights of the treated rats and mice were lower than
 

those of the corresponding matched controls during most or all of
 

the study. Survival in the rats was sufficient to allow
 

development of late-appearing tumors. In the mice, survival of
 

the high-dose males (27%), matched-control males (7%), and low-


dose females (37%) to the end of the study was low, and the
 

deaths were associated with suppurative lung lesions. However,
 

tests for dose-related trend in mortality were not significant in
 

either sex, and 47% or more of all groups of mice except control
 

males were alive at 78 weeks.
 

In the rats, a variety of neoplasms were observed in treated and
 

control groups of each sex. The lesions were of types commonly
 

found in Fischer 344 rats, and none of the incidences of tumors
 

in dosed animals were statistically significant when compared
 

with controls.
 

In the mice, the incidences of malignant lymphoma were slightly
 

higher in dosed than in control mice (males: controls 2/15, low-
 dose 8/34, high-dose 4/34; females: controls 2/15, low-dose 4/31,
 

high-dose 10/34). The incidences were not significant by any of
 

the statistical tests used, including the Tarone and Cox tests
 

using the life-table method.
 

vii
 
It is concluded that under the conditions of this bioassay,
 ethionamide was not carcinogenic in either Fischer 344 rats or
 

B6C3F1 mice.
 

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 7
 

F. Designs of Chronic Studies 8
 

G. Clinical and Pathologic Examinations 8
 

H. Data Recording and Statistical Analyses 12
 

III. Results - Rats 17
 

A. Body Weights and Clinical Signs (Rats) 17
 

B. Survival (Rats) 17
 

C. Pathology (Rats) 20
 

D. Statistical Analyses of Results (Rats) 21
 

IV. Results - Mice 23
 

A. Body Weights and Clinical Signs (Mice) 23
 

B. Survival (Mice) 23
 

C. Pathology (Mice) 26
 

D. Statistical Analyses of Results (Mice) 30
 

V. Discussion 33
 

VI. Bibliography 35
 

APPENDIXES
 

Appendix A Summary of the Incidence of Neoplasms in
 

Rats Fed Ethionamide in the Diet 37
 

Table Al Summary of the Incidence of Neoplasms in
 

Male Rats Fed Ethionamide in the Diet 39
 

Table A2 Summary of the Incidence of Neoplasms in
 

Female Rats Fed Ethionamide in the Diet 43
 

ix
 
Page 

Appendix B Summary of the Incidence of Neoplasms in 

Mice Fed Ethionamide in the Diet 47 

Table Bl Summary of the Incidence of Neoplasms in 

Male Mice Fed Ethionamide in the Diet 49 

Table B2 Summary of the Incidence of Neoplasms in 

Female Mice Fed Ethionamide in the Diet 52 

Appendix C Summary of the Incidence of Nonneoplastic 

Lesions in Rats Fed Ethionamide in the Diet 53 

Table Cl Summary of the Incidence of Nonneoplastic 

Lesions in Male Rats Fed Ethionamide in the Diet... 55 

Table C2 Summary of the Incidence of Nonneoplastic 

Lesions in Female Rats Fed Ethionamide in the Diet. 58 

Appendix D Summary of the Incidence of Nonneoplastic 

Lesions in Mice Fed Ethionamide in the Diet 61 

Table Dl Summary of the Incidence of Nonneoplastic 

Lesions in Male Mice Fed Ethionamide in the Diet... 63 

Table D2 Summary of the Incidence of Nonneoplastic 

Lesions in Female Mice Fed Ethionamide in the Diet. 66 

Appendix E Analyses of the Incidence of Primary Tumors 

in Rats Fed Ethionamide in the Diet 69 

Table El Analyses of the Incidence of Primary Tumors 

in Male Rats Fed Ethionamide in the Diet 71 

Table E2 Analyses of the Incidence of Primary Tumors 

in Female Rats Fed Ethionamide in the Diet 74 

Appendix F Analyses of the Incidence of Primary Tumors 

in Mice Fed Ethionamide in the Diet 79 

Table Fl Analyses of the Incidence of Primary Tumors 

in Male Mice Fed Ethionamide in the Diet 81 

Table F2 Analyses of the Incidence of Primary Tumors 

in Female Mice Fed Ethionamide in the Diet 84 
Table 1

 

Table 2 

Figure 1 

Figure 2 

Figure 3 

Figure 4 

Figure 5 

TABLES
 

Design of Ethionamide Chronic Feeding
 

Studies in Rats
 

Design of Ethionamide Chronic Feeding
 

Studies in Mice
 

FIGURES
 

Growth Curves for Rats Fed Ethionamide
 

in the Diet
 

Survival Curves for Rats Fed Ethionamide
 

in the Diet
 

Growth Curves for Mice Fed Ethionamide
 

in the Diet
 

Survival Curves for Mice Fed Ethionamide
 

in the Diet
 

Life Table for Mice Fed Ethionamide
 

in the Diet: Lymphoma
 

Page 

10
 

18
 

19
 

24
 

25
 

31
 

xi
 

I. INTRODUCTION
 

Ethionamide (CAS 536-33-4; NCI C01694) is a synthetic antitubercular drug. It is tuberculostatic for Mycobacteriutn tuberculosis
 

and atypical mycobacteria, the etiological agents for tuberculosis (Weinstein, 1975). Use of ethionamide is reserved for
 

cases that have become resistant to treatment with primary drugs.
 

This practice has been adopted because of allergic reactions,
 

gastro-intestinal disturbances, and the relatively high risk of
 

liver damage associated with ethionamide treatment (Weinstein,
 

1975; Smith, 1977). After absorption, ethionamide is distributed
 

widely in tissues and plasma, as well as in the cerebrospinal
 

fluid, making it useful for treating meningeal infections (Smith,
 

1977). The adult dose ranges from 0.5 to 1.0 g/day for a period
 

of 1 to 2 years.
 

Ethionamide was selected for screening in the carcinogenesis
 

bioassay program in an attempt to evaluate the carcinogenicity of
 

certain drugs that are used for prolonged periods of time in
 

humans.
 

II. MATERIALS AND METHODS
 

A. Chemical
 

Ethionamide (2-ethylthioisonicotinamide) was obtained in two
 

batches from the Ives Laboratories, Inc., New York, N.Y. The
 

purity of the batch used in the chronic studies (Lot No. 24) was
 

determined to be 98.9 + 1.2% by thiourea titration at Midwest
 

Research Institute. No attempt was made to identify or
 

quantitate impurities. The melting point of Lot No. 24 was
 

159.5-163.5°C (literature: 161-163.5<>C). Elemental analyses (C,
 

H, N, S) were correct for C8HlQN2s» the molecular formula of
 

ethionamide. The identity was confirmed by nuclear magnetic
 

resonance, infrared, and ultraviolet spectra, which were in
 

agreement with the structure and matched the spectra in the
 

literature.
 

The chemical used for the chronic studies was stored in a cold
 

room at 5oc.
 

B. Dietary Preparation
 

Test diets were prepared every 2 weeks by mixing a known amount
 

(B)
 

of sifted ethionamide with a small amount of Wayne Lab Blox
 

animal meal (Allied Mills, Inc., Chicago, 111.) in a portable
 

mixer, then adding this mixture to the required amount of animal
 
meal and mixing in a twin-shell blender for 10 minutes. The
 

prepared diets were stored at room temperature in sealed plastic
 

containers. No concentration or stability analyses of the
 

chemical in the feed were performed.
 

C. Animals
 

Animals used in the bioassay were obtained through contracts of
 

the Division of Cancer Treatment, National Cancer Institute. For
 

the subchronic studies, male Sprague-Dawley rats and male Swiss
 

mice were obtained from Charles River Breeding Laboratories,
 

Inc., Wilmington, Massachusetts. The animals were approximately
 

40 days of age when received at the laboratory, and were
 

quarantined for 5 days as an acclimation period prior to the
 

start of the subchronic study.
 

For the chronic studies, Fischer 344 rats of each sex were
 

obtained from Harlan Industries, Cumberland, Indiana, and B6C3F1
 

mice of each sex were obtained from A. R. Schmidt, Madison,
 

Wisconsin. The rats were 30 days of age when received and the
 

mice were 36 days of age. All animals were quarantined for an
 

acclimation period (rats for 11 days, mice for 34 days). Those
 

animals with no visible signs of disease were then assigned to
 

control or dosed groups and earmarked for individual
 

identification.
 
D. Animal Maintenance
 

All animals were housed in temperature- and humidity-controlled
 

rooms. The temperature range was 20-24°C, and the relative
 

humidity was maintained at 40-60%. Room air was changed 15 times
 

per hour and passed through both intake and exhaust fiberglass
 

roughing filters. In addition to natural light, illumination was
 

provided by fluorescent light for 9 hours per day. Food and
 

water were supplied daily and were made available ad libitum.
 

Rats and mice were housed five per cage in solid-bottom stainless
 

steel cages (Hahn Roofing and Sheet Metal Co., Birmingham, Ala.).
 

The bottoms of the rat cages were lined with Iso-Dri hardwood
 

chips (Carworth, Edison, N.J.), and the cage tops were covered
 

with disposable filter bonnets; mouse cages were provided with
 

Sterolit clay bedding (Englehard Mineral and Chemical Co., New
 

York, N.Y.). Bedding was replaced once per week; cages, water
 

bottles, feeders were sanitized at 82°C once per week; racks were
 

cleaned once per week.
 

The rats and mice were housed in separate rooms. Control animals
 

were housed with respective dosed animals. Animals dosed with
 

ethionamide were maintained in the same rooms as animals of the
 

same species being dosed with the following chemicals:
 
RATS
 

Feed Studies
 

4-acetyl-N-((cyclohexylamino)carbonyl)benzenesulfonamide
 

(acetohexamide) (CAS 968-81-0)
 

anthranilic acid (CAS 118-92-3)
 

l-butyl-3-(p-tolylsulfonyl)urea (tolbutamide) (CAS 64-77-7)
 

4-chloro-N-((propylamino)carbonyl)benzenesulfonamide
 

(chlorpropamide) (CAS 94-20-2)
 

5-(4-chlorophenyl)-6-ethyl-2,4-pyrimidinediamine
 

(pyrimethamine) (CAS 58-14-0)
 

2,6-diamino-3-(phenylazo)pyridine hydrochloride
 

(phenazopyridine hydrochloride) (CAS 136-40-3)
 

L-tryptophan (CAS 73-22-3)
 

N-9H-fluoren-2-ylacetamide (CAS 53-96-3)
 

N-(p-toluenesulfonyl)-N'-hexamethyleniminourea
 

(tolazamide) (CAS 1156-19-0)
 

1-phenethylbiguanide hydrochloride (phenformin) (CAS 114-86-3)
 

pyrazinecarboxamide (pyrazinamide) (CAS 98-96-4)
 

4,4'-sulfonyldianiline (dapsone) (CAS 80-08-0)
 

4,4'-thiodianiline (CAS 139-65-1)
 

MICE
 

Feed Studies
 

4-acetyl-N-((eyelohexylamino)carbonyl)benzenesulfonamide
 

(acetohexamide) (CAS 968-81-0)
 

anthranilic acid (CAS 118-92-3)
 

l-butyl-3-(p-tolylsulfonyl)urea (tolbutamide) (CAS 64-77-7)
 

4-chloro-N-((propylamino)carbonyl)benzenesulfonamide
 

(chlorpropamide) (CAS 94-20-2)
 

5-(4-chlorophenyl)-6-ethyl-2,4-pyrimidinediamine
 

(pyrimethamine) (CAS 58-14-0)
 

2,6-diamino-3-(phenylazo)pyridine hydrochloride
 

(phenazopyridine hydrochloride) (CAS 136-40-3)
 

L-tryptophan (CAS 73-22-3)
 

N-9H-fluoren-2-ylacetamide (CAS 53-96-3)
 

N-(p-toluenesulfonyl)-N'-hexamethyleniminourea
 

(tolazamide) (CAS 1156-19-0)
 

1-phenethylbiguanide hydrochloride (phenformin) (CAS 114-86-3)
 

pyrazinecarboxamide (pyrazinamide) (CAS 98-96-4)
 

4,4'-sulfonyldianiline (dapsone) (CAS 80-08-0)
 

4,4'-thiodianiline (CAS 139-65-1)
 
Gavage Studies
 

cholesterol (p-(bis(2-chloroethyl)amino)phenyl)acetate
 

(phenesterin) (CAS 3546-10-9)
 

estradiol bis((p-(bis(2-chloroethyl)amino)phenyl)acetate)
 

(estradiol mustard) (CAS 22966-79-6)
 

Intraperitoneal Injection Studies
 

4'-(9-acridinylamino)methansulfon-m-aniside monohydrochloride
 

(MAAM) (NSC 141549)
 

acronycine (CAS 7008-42-6)
 

5-azacytidine (CAS 320-67-2)
 

beta-2'-deoxy-6-thioguanosine monohydrate (beta-TGdR)
 

(CAS 789-61-7)
 

1,4-butanediol dimethanesulfonate (busulfan) (CAS 55-98-1)
 

emetine dihydrochloride tetrahydrate (CAS 316-42-7)
 

3,3'-iminobis-l-propanol dimethanesulfonate (ester)
 

hydrochloride [IPD] (CAS 3458-22-8)
 

(+)-4,4'-(1-methyl-l,2-ethanediyl)bis-2,6-piperazinedione
 

(ICRF-159) (CAS 21416-87-5)
 

N,3-bis(2-chloroethyl)tetrahydro-2H-l,3,2-oxazaphosphorin-2­

amine-2-oxide (isophosphamide) (CAS 3778-73-2)
 

N-(2-chloroethyl)-N-(l-methyl-2-phenoxyethyl)benzylamine
 

hydrochloride (phenoxybenzamine) (CAS 63-92-3)
 

N-(l-methylethyl)-4-((2-methylhydrazino)methyl)benzamide
 

monohydrochloride (procarbazine) (CAS 366-70-1)
 

tris(l-aziridinyl)phosphine sulfide (thio-TEPA) (CAS 52-24-4)
 

2,4,6-tris(dimethylamino)-s-triazine (CAS 645-05-6)
 

E. Subchronic Studies
 

Subchronic feeding studies were conducted to estimate the maximum
 

tolerated doses of ethionamide, on the basis of which low and
 

high concentrations (hereinafter referred to as "low doses" and
 

"high doses") were determined for administration in the chronic
 

studies. Ethionamide was administered in the diet for 45 days to
 

male Sprague-Dawley rats at doses of 1,200, 3,000, 6,000, 15,000,
 

or 30,000 ppm and to male Swiss mice at doses of 2,000, 5,000,
 
10,000, 25,000, or 50,000 ppm. Following administration of the
 

chemical, all animals were observed for an additional 45 days.
 

Five animals of each species were tested at each dose, and 10
 

animals of each species were maintained as untreated controls.
 

All rats treated at 15,000 and 30,000 ppm died, and one animal
 

treated at 6,000 ppm died. The mean body weight gains of dosed
 

animals when compared with controls were 75% at 6,000 ppm, 82% at
 

3,000 ppm, and approximately same as controls at 1,200 ppm. The
 

low and high doses for the chronic studies using rats were set at
 

1,500 and 3,000 ppm.
 

In mice, all animals treated at 25,000 and 50,000 ppm died, and
 

two animals dosed at 10,000 ppm died. The mean body weight gains
 

were unaffected in mice treated at 10,000 ppm and below. No
 

gross abnormalities were seen in any animals at necropsy. The
 

low and high doses for the chronic studies using mice were set at
 

1,000 and 2,000 ppm.
 

F. Designs of Chronic Studies
 

The designs of the chronic studies are shown in tables 1 and 2.
 

G. Clinical and Pathologic Examinations
 

All animals were observed twice daily for signs of toxicity, and
 

- imals that were moribund were killed and necropsied, except for
 
Table 1. Design of Ethionamide Chronic Feeding Studies in Rats
 

Sex and Initial Ethionamide Time on Study 

Test No. of in Diet Dosedc Observed 

Group Animals3 iiymlb (weeks) (weeks) 

MALE 

Matched-Control 15 0 104 

Low-Dose 35 1,500 78 26 

High-Dose 34 3,000 78 25 

FEMALE 

Matched-Control 15 0 104 

Low-Dose 35 1,500 78 26 

High-Dose 35 3,000 78 26 

a

Rats were 41 days of age when placed on study.
 

^Dosed animals were fed test diets 5 days per week and control
 

diets 2 days per week.
 

C

A11 rats were placed on study on the same day.
 
Table 2. Design of Ethionamide Chronic Feeding Studies in Mice
 

Sex and 

Test 

Group 

Initial 

No. of 

Animals3 

Ethionamide 

in Diet 

(ppm)b . 

Time 

Dosedc 

(weeks ) 

on Study 

Observed 

(weeks ) 

MALE 

Matched-Control 15 0 104 

Low-Dose 35 1,000 78 26 

High-Dose 34 2,000 78 26 

FEMALE 

Matched-Control 15 0 104 

Low-Dose 35 1,000 78 26 

High-Dose 35 2,000 78 26 

a

Mice were 70 days of age when placed on study.
 

animals were fed test diets 5 days per week and control
 

diets 2 days per week.
 

C

A11 mice were placed on study on the same day.
 

10
 
those dying prior to day 100, due, presumably, to toxicity of the
 

test chemical. Rats and mice were weighed individually every 2
 

weeks to week 75, then approximately once per month for the
 

remainder of the study. Palpation for masses was carried out at
 

each weighing.
 

The pathologic evaluation consisted of gross and microscopic
 

examination of major tissues, major organs, and all gross lesions
 

from killed animals and from animals found dead. The following
 

tissues were examined microscopically: skin, muscle, lungs and
 

bronchi, trachea, bone and bone marrow, spleen, lymph nodes,
 

thymus, heart, salivary gland, liver, gallbladder and bile duct
 

(mice), pancreas, esophagus, stomach, small intestine, large
 

intestine, kidney, urinary bladder, pituitary, adrenal, thyroid,
 

parathyroid, mammary gland, prostate, or uterus, testis or ovary,
 

brain, and sensory organs. Peripheral blood smears were prepared
 

from each animal whenever possible. Occasionally, additional
 

tissues 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 tissues from some animals were not examined, particularly
 

from those animals that died early. Also, some animals were
 

missing, cannibalized, or judged to be in such an advanced state
 

11
 
of autolysis as to preclude histopathologic evaluation. Thus,
 

the number of animals from which particular organs or tissues
 

were examined microscopically 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 automatic data processing system, the Carcinogenesis Bioassay Data
 

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

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
 

12
 
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
 

in which that site is examined (denominator). In most instances,
 

the denominators included only those animals for which that site
 

was examined histologically. However, when macroscopic examination was required to detect lesions prior to histologic sampling
 

(e.g., skin or mammary tumors), or when lesions could have
 

appeared at multiple sites (e.g., lymphomas), the denominators
 

consist of the numbers of animals necropsied.
 

The purpose of the statistical analyses of tumor incidence is to
 

determine whether animals receiving the test chemical developed a
 

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
 

13
 
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 relationship. 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
 

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
 

14
 
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
 

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
 

15
 
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 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.
 

16
 
III. RESULTS - RATS
 

A. Body Weights and Clinical Signs (Rats)
 

Mean body weights of both the low- and high-dose male rats were
 

lower than those of the matched controls (figure 1). Mean body
 

weights of the high-dose females were lower throughout the study,
 

while those of the low-dose females were similar to those of the
 

controls for the first 50 weeks, and lower thereafter. Fluctuations in the growth curve may be due to mortality; as the size of
 

the group diminishes, the mean body weight may be subject to wide
 

variation. No other signs of toxicity related to chemical
 

administration were recorded in rats.
 

B. Survival (Rats)
 

The Kaplan and Meier curves estimating the probabilities of
 

survival for male and female rats fed ethionamide in the diet at
 

the doses of this experiment, together with those of the
 

controls, are shown in figure 2.
 

The results of the Tarone test for positive dose-related trend in
 

mortality are not significant in either sex. In male rats, 19/34
 

(56%) of the high-dose group, 20/35 (57%) of the low-dose group,
 

and 9/15 (60%) of the matched controls lived to the end of the
 

study. The females survived longer than the males, with 25/35
 

17
 
400 - D 

D D 1 '~'Ll|-.LJ1n

­

OO OO o (^ O ("} O 

350­ O 

DDDD

 0S0000o0° ° ° A A £ 

5 D

° 000 ° A AAA AAAAAAA A 

i- 300-

DDOO°O AA AAA 

o 8§OO A A LU 250- A A 

g OAAAA A 

Q DAA 

O 200- A 

00 § z 

LU 150­

§ 

MALE RATS 

> D MATCHED CONTROL 

5 

100 •] 

O LOW DOSE 

A HIGH DOSE 

50­

0u -| ­ , , , , , , ! ( ! 1 

0 10 20 30 40 50 60 70 80 90 100 11 

TIME ON STUDY (WEEKS) 

400­

350­

5 D 300- D a n a a

DDDDDD°°0o A A 

250- o° ° °° ! 

O nLl/-,Ori A AAA A AAAAA A

 

CO 200- ogQg88o° ° AAAA

O AA A AAAA 

Z C^ A AAAAAA 

LU 

2 150­ SA AA 

nXA FEMALE RATS 

V D MATCHED CONTROL 

100 

O LOW DOSE 

5C A HIGH DOSE 

0 -J 1 | | 1 1 1 1 T 1 

0 10 20 30 40 50 60 70 80 90 100 11 

TIME ON STUDY (WEEKS) 

Figure 1. Growth Curves for Rats Fed Ethionamide in the Diet 

18 

Y WEIGH

T ( 
PROBABILIT

Y OF SURVIVAL PROBABILIT

Y O

CD 

tSJ 

o : V) r-S

 It

0 > m 

|. 

1 I

I t*~ 

BJ 

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% 

-i 

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(71%) of the high-dose group, 25/35 (71%) of the low-dose group
 

and 12/15 (80%) of the matched controls living to termination of
 

the study. The high survival in the different groups allowed
 

development of late-appearing tumors and provided a sufficient
 

number of rats of each sex for meaningful statistical analyses of
 

the incidences of tumors that appeared during the 104-week
 

bioassay.
 

C. Pathology (Rats)
 

Histopathologic findings on neoplasms in rats are summarized in
 

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

are summarized in Appendix C, tables Cl and C2.
 

A variety of neoplasms were observed in both the control and
 

treated groups. These lesions, and their frequency, however, are
 

not uncommon in this strain of rat independent of any chemical
 

administration. The majority of tumors observed were benign.
 

In addition to the neoplastic lesions, a number of degenerative,
 

proliferative, and inflammatory changes were encountered also in
 

animals of the control and treated groups (Appendix C). These
 

nonneoplastic lesions are commonly seen in aged Fischer 344 rats.
 

In the judgment of the pathologists, ethionamide was not
 

20
 
carcinogenic in Fischer 344 rats under the conditions of this
 

bioassay.
 

D. Statistical Analyses of Results (Rats)
 

Tables El and E2 in Appendix E 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% in one or more than one group.
 

The results of the Cochran-Armitage test for positive dose-


related trend and of the Fisher exact test for direct comparisons
 

of control and dosed groups in the positive direction are not
 

significant in either sex. In male rats, the incidence of
 

leukemia has a significant trend in the negative direction. In
 

female rats, fibroadenoma of the mammary gland appears at a
 

significantly higher incidence in the matched-control group than
 

in either dosed group. In each of the 95% confidence intervals
 

of relative risk, shown in the tables, the value of one or less
 

than one is included; this indicates the absence of significant
 

positive results. It should also be noted that each of the
 

intervals except the incidence of fibroadenoma of the mammary
 

gland in high-dose female rats has an upper limit greater than
 

one, indicating the theoretical possibility of the induction of
 

21
 
tumors by ethionamide, which could not be detected under the
 

conditions of this test.
 

22
 
IV. RESULTS - MICE
 

A. Body Weights and Clinical Signs (Mice)
 

Mean body weights of both the low- and high-dose male and female
 

mice were lower than those of the matched controls from week 10
 

to week 70 (figure 3). Fluctuations in the growth curve may be
 

due to mortality; as the size of the group diminishes, the mean
 

body weight may be subject to wide variation. No other signs of
 

toxicity related to chemical administration were observed in the
 

mice.
 

To control respiratory disease, mice in the colony were treated
 

with oxytetracycline in the drinking water at 0.6 mg/ml during
 

week 54 and at 0.3 mg/ml during week 55. Also, propylene glycol
 

was vaporized in the mouse rooms for about 2 months beginning at
 

week 54.
 

B. Survival (Mice)
 

The Kaplan and Meier curves estimating the probabilities of
 

survival for male and female mice fed ethionamide in the diet at
 

the doses of this experiment, together with those of the
 

controls, are shown in figure 4.
 

The results of the Tarone test for positive dose-related trend in
 

mortality are not significant in either sex. In male mice, 9/34
 

23
 
45­

40­

35­

2 30H 

IO 

UJ 25­

o 

o 

CO 

Uj 15­

S 

10­

5­

45 

40­

35­

2 so H 

X 

2 

U 25 ­ J 

O 

O 

GO "ll 

15 ­ UJ 

10­

5 ­

DDD 

DDDD 

ODD DD ° O O O O 

O O A 

A A 

D 

g;°g^Ag A a 

MALE MICE 

D MATCHED CONTROL 

O LOW DOSE 

A HIGH DOSE 

10 20 30 40 50 70 80 90 100 110 

TIME ON STUDY (WEEKS) 

DODDDDDDD _DD D A A 

D 8 D QD A A 

D OOD D n n 0.0 O D D 

A.2°. 3 OO O OOAA 00 

O 

O -°^ AA 

A

—*v 

no 

FEMALE MICE 

D MATCHED CONTROL 

O LOW DOSE 

A HIGH DOSE 

10 20 30 40 50 60 70 80 90 100 110 

TIME ON STUDY (WEEKS) 

Figure 3. Growth Curves for Mice Fed Ethionamide in the Diet 

24 
PROBABILITY OF SURVIVAL 

O p O O C 

g § g S 

-g 

CO 

ro 

Ui 

3 

OL 

n 

CD 

a 

n' 

PROBABILITY OF SU
(26%) of the high-dose group, 19/35 (54%) of the low-dose group,
 

and only 1/15 (7%) of the matched controls lived to the end of
 

the study. In female mice, 21/35 (60%) of the high-dose group,
 

13/35 (37%) of the low-dose group, and 10/15 (67%) of the matched
 

controls survived to termination of the study. In male mice, all
 

the high-dose animals, 33 of the low-dose animals, and 13 of the
 

controls were alive at week 52. By week 78, 16 of the high-dose
 

animals, 29 of the low-dose animals, and 6 of the controls were
 

still alive. In females, all the high-dose animals, 33 of the
 

low-dose animals, and 14 of the controls were alive at week 52.
 

By week 78, 31 of the high-dose animals, 18 of the low-dose
 

animals, and 12 of the controls were still alive.
 

C. Pathology (Mice)
 

Histopathologic findings on neoplasms in mice are summarized in
 

Appendix B, tables Bl and B2; findings on nonneoplastic lesions
 

are summarized in Appendix D, tables Dl and D2.
 

Excluding the lymphoreticular tumors, the neoplasms listed in
 

Appendix B appeared with greater frequency in the control mice.
 

The incidence of lymphoreticular neoplasms, which was higher in
 

the dosed than in the control groups, was the highest in the
 

26
 
low-dose males and high-dose females. The incidences of these
 

lesions were as follows: 

MALE 

Untreated Low High 

Control Dose Dose 

Number of mice necropsied (15) (34) (34) 

Brain* (15) (34) (32) 

malignant lymphoma, histiocytic type 0 0 2 

Trigeminal ganglion 

malignant lymphoma, mixed type 0 0 1 

Multiple organs, lymphoreticular 

malignant lymphoma, NOS 

(not otherwise specified) 0 1 0 

malignant lymphoma, lymphocytic or 

lymphoblastic (undifferentiated) type 1 0 1 

malignant lymphoma, histiocytic type 1 6 0 

Spleen* (15) (34) (34) 

malignant lymphoma, histiocytic type 0_ 1 0 

Total number of animals with tumors 2 8 4 

*Number of mice with tissue examined microscopically 

27
 
FEMALE
 

Untreated Low High
 

Control Dose Dose
 

Number of mice necropsied (15) (31) (34)
 

Multiple organs, lymphoreticular
 

malignant lymphoma, NO S 0 0 1
 

malignant lymphoma, lymphocytic or lymphoblastic (undifferentiated) type 0 2 3
 

malignant lymphoma, histiocytic type 2 0 4
 

Spleen* (14) (31) (33)
 

malignant lymphoma, histiocytic type 0 0 1
 

Pancreatic lymph node* (12) (26) (30)
 

malignant lymphoma, lymphoblastic
 

(undif ferentiated) type 0 0 1
 

malignant lymphoma, mixed type 0 1 0
 

Mesenteric lymph node (12) (26) (30)
 

malignant lymphoma, lymphoblastic
 

(undif ferentiated) type 0 1 0
 

Total number of animals with tumors 2 4 10
 

Number of mice with tissue examined microscopically
 

The brains of three animals and the trigeminal nerve of one
 

animal had lymphomatous infiltrates. The neoplastic cells were
 

lymphoid in appearance, having a large pleomorphic nucleus that
 

stained basophilic and a minimal amount of eosinophilic
 

cytoplasm. Within the brain, the cellular infiltrate involved
 

the choroid plexuses and meninges most often. The perineural
 

tissues of the trigeminal nerve as well as the nerve itself were
 

infiltrated with these neoplastic lymphoid cells.
 

28
 
The malignant lymphomas were classified as lymphocytic, histiocytic, or mixed types. The lymphocytic type was comprised of
 

cells having a small, darkly basophilic to large, lightly
 

basophilic vesicular nucleus and a rim of eosinophilic cytoplasm.
 

Malignant lymphomas composed of lymphoblastic or undifferentiated
 

cells were also included in the lymphocytic type. The
 

histiocytic type was comprised primarily of cells with a large
 

open-faced vesicular nucleus, distinct eosinophilic nucleolus,
 

and an abundant eosinophilic cytoplasm. However, some
 

histiocytic tumors contained many cells having a smaller, pleomorphic nucleus that was often elliptical or indented. The mixed
 

type was a combination of the lymphocytic and histiocytic cell
 

types. The malignant lymphomas, NOS, had cellular distortion
 

which prevented further classification.
 

The malignant lymphomas were either generalized, involving
 

several organs, or solitary, involving only one organ. The
 

generalized lymphomas usually involved the spleen, liver, and one
 

or more lymph nodes. The solitary lymphomas involved the spleen,
 

pancreatic lymph nodes, or mesenteric lymph nodes.
 

In addition to the neoplastic lesions, a number of degenerative,
 

proliferative, and inflammatory changes were encountered also in
 

animals of the dosed and control groups (Appendix D). These
 

nonneoplastic lesions are commonly seen in aged B6C3F1 mice;
 

29
 
however, the suppurative lesions involving the lungs were
 

associated with increased deaths, which were especially prominent
 

in the low-dose females, high-dose males, and control males.
 

In this bioassay the incidence of lymphoreticular neoplasms was
 

slightly higher in the dosed mice, particularly the females, than
 

in the controls. Because the differences in incidences between
 

dosed and control groups were small, in the judgment of the
 

pathologists, ethionamide was not considered to be carcinogenic.
 

D. Statistical Analyses of Results (Mice)
 

Tables Fl and F2 in Appendix F 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% in one or more than one group.
 

The results of the Cochran-Armitage test for positive dose-


related trend and of the Fisher exact test for direct comparisons
 

of control and dosed groups are not significant in either sex.
 

Due to the early mortality, the life-table method is used to
 

analyze the incidence of lymphoma in both males and females
 

(figure 5). In this life-table analysis, neither the results of
 

the Tarone test using three groups nor the results of the Cox
 

test for comparison of each treated group with the control group
 

were significant in either sex.
 

30
 
PROBABILITY OF SURVIVAL WITHOUT KNOWN TUMOR

 PROBABILITY OF SURVIVAL WIT

3 =3 e3 ?3 C3 <a f3 •* cs ca ca

 e 

!

s ?3

0 < • e J 3 s1 !! !3 Cs } c3 J3 S S§ i§ g3 a3 £s so 5 

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 [> D D —, x =K 01- r1 w 

CD 5 P

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 ^

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o il 

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o 

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- Z o>. m * §-

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w. OI a-' 
The current historical records of this laboratory indicate an
 

overall incidence of malignant lymphoma of 35/586 (6%) in male
 

mice and 51/588 (9%) in female mice. The incidences within
 

individual control groups range from U/20 to 4/14 (28%) in male
 

mice and from 0/20 to 6/15 (40%) in female mice.
 

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 ethionamide, which could not be detected under the conditions
 

of this test.
 

32
 
V. DISCUSSION
 

The mean body weights of the low- and high-dose rats and mice fed
 

diets containing ethionamide were lower than those of the corresponding matched controls during most or all of the bioassay.
 

Survival in the rats was sufficient to allow development of late-


appearing tumors. Tests for dose-related trend in mortality were
 

not significant in either rats or mice. In the mice, a high
 

incidence of suppurative lung lesions were associated with
 

decreased life spans, particularly for low-dose females, high-


dose males, and matched-control males. While only 1 control, 19
 

low-dose, and 9 high-dose male mice and only 10 control, 13 low-


dose, and 21 high-dose female mice lived to the end of the study,
 

at week 78 there were 6, 29, and 16 males and 12, 18, and 31
 

females in the respective groups.
 

In the rats, a variety of neoplasms were observed in treated and
 

matched-control groups of both sexes. The lesions were of types
 

commonly found in Fischer 344 rats, and none of the incidences of
 

tumors were statistically significant.
 

In the mice, the incidences of malignant lymphoma were slightly
 

higher in dosed than in control mice (males: controls 2/15,
 

low-dose 8/34, high-dose 4/34; females: controls 2/15, low-dose
 

4/31, high-dose 10/34. The incidences were not significant by
 

33
 
any of the statistical tests used, including the Tarone and Cox
 

tests using the life-table method; also, they are within the
 

ranges of 0/20 to 4/14 (28%) observed in this laboratory for
 

individual groups of historical-control male B6C3F1 mice (overall
 

incidence of 35/586, or 6%) and within the range of 0/20 to 6/15
 

(40%) for individual groups of historical-control female B6C3F1
 

mice (overall incidence of 51/588, or y%).
 

One long-term study with ethionamide has been reported
 

(Biancifiori et al. , 1964). Female BALB/c/Cb/Se mice were given
 

intragastric instillations of 0.1 ml of 2% ethionamide in
 

propylene glycol 6 days per week for 50 weeks. Seven of the 33
 

dosed mice developed thyroid tumors between 28 and 69 weeks,
 

compared with 0/18 surviving controls receiving propylene glycol
 

alone and 0/47 untreated controls. Five of the tumors were
 

papillary carcinomas and two were epidermoid carcinomas. In the
 

present bioassay, no lesions of the thyroid were found in the
 

dosed rats or mice at an incidence above that in the matched
 

controls.
 

It is concluded that under the conditions of this bioassay,
 

ethionamide was not carcinogenic in either Fischer 344 rats or
 

B6C3F1 mice.
 

34
 
VI. BIBLIOGRAPHY
 

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

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

Berenblum, I., ed., Carcinogenicity Testing; A Review of the
 

Panel on Carcinogenicity of the Cancer Research Commission
 

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

Geneva, 1969.
 

Biancif iori, C. , Milia, U. , and DiLeo, F. P. , Tumori della
 

tiroide indotti mediante etionamide (ET) in topi femmina 

vergini BALB/c/Cb/Sc substrain. Lav. Anat. Pat. Perugia 

J24:145-166, 1964. 

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

Soc. B 34:187-220, 1972.
 

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

1970, pp. 48-52.
 

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

significance tests, confidence limits and adjustments for
 

stratification. Rev. Int. Statist. Inst. 39:148-169, 1971.
 

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

incomplete observations. J. Am. Statist. Assoc. 53:457-481,
 

1958.
 

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.
 

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

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

induced by different numbers of adminstrations of benzo (a)
 

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

Smith, H., Chemotherapy of tuberculosis. In: Antibiotics in
 

Clinical Practice, University Park Press, Baltimore, 1977,
 

pp. 289-309.
 

35
 
Tarone, R. E., Tests for trend in life table analysis.
 

Biometrika 62679-682. 1975.
 

V/einstein, L., Antimicrobial agents: general considerations.
 

In: The Pharmacological Basis of Therapeutics, Goodman, L.
 

S. and Oilman, A., eds., Macmillan Publishing Co., Inc., New
 

York, 1975, pp. 1101 and 1212-1216.
 

36
 
APPENDIX A
 

SUMMARY OF THE INCIDENCE OF NEOPLASMS IN
 

RATS FED ETHIONAMIDE IN THE DIET
 

37
 

TABLE A1.

 

SUMMARY OF THE INCIDENCE OF NEOPLASMS IN MALE 

RATS FED ETHIONAMIDE IN THE DIET 

MATCHED LOW DOSE HIGH DOSE
 

CONTROL
 

ANIMALS INITIALLY IH STUDY 15 35 3«
 ANIMALS NECBOPSIED 15 35 33
 

ANIMALS EXAMINED HISTOPATHOLOGICALLY 15 35 33
 

INTEGUMENTARY SYSTEM
 

*SKIN (15) (35) (33)
 

SQUAHOUS CELL PAPILLONA 1 (3%)
 

*SOBCOT TISSUE (15) (35) (33)
 

FIBROMA 2 (6%)
 

FIBROSARCONA 1 (3%)
 

HESPIHATOBY SYSTEM
 

ILONG (15) (35) (33)
 

ALVEOLAR/BRONCHIOLAR ADENOMA 1 (7X)
 

HEHATOPOIETIC SYSTEM
 

*MULTIPLE ORGANS (15) (35) (33)
 

UNDIFFEHENTIATED LEUKEMIA 2 (13X) 4 (IH) 1 (3S)
 

GRANOLOCYTIC LEOKEHIA 1 (7«)
 

HONOCYTIC LEUKEMIA 1 (3%)
 

*THYMUS (1t) (35) (31)
 

THYMOHA 1 (7X)
 

CIRCULATORY SYSTEM
 

NONE
 

DIGESTIVE SYSTEfl
 

tLITEH (15) (35) (33)
 

* NOHBEB OF ANIMALS HITH TISSUE EXAMINED MICROSCOPICALLY
 * SOMBER OF ANIMALS NECROPSIED
 

39
 
TABLE A1. MALE RATS: NEOPLASMS (CONTINUED) 

MATCHED LOW DOSE
 

CONTROL
 

HEPATOCELLULAB CARCINOHA
 

URINARY SYSTEM
 

•KIDNEY	 (15) (35)
 

CARCINOMA, NOS 1 (3%)
 

ENDOCRINE SYSTEM
 

tPITUITARY (1U) (34)
 

CHBOHOPHOBE ADENOMA 1 (7X) 1 (3%)
 

•ADRENAL	 (15) (35)
 

PHEOCHHOHOCYTOMA. MALIGNANT 1 (7X)
 

•THYROID	 (15) (35)
 

C-CELL ADENOMA 3 (20X) 2 (6*)
 

C-CELL CARCINOMA
 

•PANCREATIC	 ISLETS (15) (35)
 

ISLET-CELL ADENOMA 1 (3S)
 

ISLET-CELL CABCINOMA 1 (3X)
 

HEPRODOCTIVE SYSTEM 

•PREPOTIAL GLAND 

ADENOMA, NOS 

(15) 

1 (7X) 

(35) 

•TBSTIS 

INTERSTITIAL-CELL TOMOR 

(15) 

13 (87X) 

(3<») 

32 (94X) 

NERVOUS SYSTEM
 

NONE
 

SPECIAL SENSE ORGANS
 

'EXTERNAL EAR (15) (35)
 

SQOAMOOS CELL PAPILLOMA 1 (7X)
 

*ZYBBAL'S GLAND (15) (35)
 

SQOAH005 CELL PAPILLOMA _ 1 J3X1
 

I NUMBER OF ANIMALS WITH TISSUE EXAMINED MICROSCOPICALLY
 

*	 NUMBER OF ANIMALS NECROPSIED
 

HIGH DOSE
 

1 (3*)
 

(33)
 

(29)
 

(33)
 

(30)
 

1 (3X)
 

1 (3%)
 

(33)
 

(33)
 

(33)
 

31 (94X)
 

(33)
 

(33)
 

40
 
TABLE A1. MALE RATS: NEOPLASMS (CONTINUED)
 

MATCHED LOW DOSE HIGH DOSE
 

CONTROL
 

MUSCOLOSKELETAL SYSTEM
 

NONE
 

BODY CAVITIES
 

*ABDOHINAL CAVITY (15) (35) (33)
 

MESOTHELIOMA, NOS 1 (3X)
 

ALL OTHER SYSTEMS
 

THORAX
 

SABCONA, NOS 1
 

— — — _ —— — ——_ — ._.— .- —— _.— — — *— — — — — — — — — _ — —— — —— ——— — — — — »— — — — — — — — —. — — —— — _ — — — 4 — —— — — — — — ^^^^— —
 . 

ANIHA L DISPOSITION SUMMAR Y 

ANIMALS INITIALLY IN STUDY 15 35 34 

NATURAL DEATHd 2 2 7 

MORIBUND SACRIFICE U 13 8 

SCHEDULED SACRIFICE 

ACCIDENTALLY KILLED 

TERMINAL SACRIFICE 9 20 19 

ANIMA L HISSING 

t NUMBER OF ANIMALS WITH TISSUE EXAMINED MICROSCOPICALLY 

* NUMBER OF ANIMALS NECROPSIED 

41 
TABLE A1. MALE RATS: NEOPLASMS (CONTINUED)
 

MATCHED LOW DOSE HIGH DOSE 

CONTROL 

TUHOfi SUMMAR Y 

TOTAL ANIflALS WITH PRIMAR Y TOflORS* 14 34 31 

TOTAL PRIMAR Y TUMORS 26 50 35 

TOTAL ANIflALS HITH BENIGN TUMORS 14 33 31 

TOTAL BENIG N TDMORS 21 41 32 

TOTAL ANIMAL S HITH MALIGNAN 5 T TUMORS 8 3 

TOTAL MALIGNAN T TUMORS 5 8 3 

TOTAL ANIMALS KITH SECONDARY TUMORS* 

TOTAL SECONDARY TUMORS 

TOTAL AHIHALS HITH TUMORS ONCERTAINBENIGN OR MALIGNAN T 1

 

TOTAL UNCERTAIN TUMORS 1 

TOTAL ANIMAL S HITH TUMORS UNCERTAINPRIMAR Y OB METASTATIC

 

TOTAL UNCERTAIN TUMORS 

* PRIMAR Y TUMORS: ALL TUMORS EXCEPT SECONDARY TUMORS 

* SECONDARY TUMORS: METASTATIC TUMORS OR TUMORS INVASIV E INTO AN ADJACEN T ORGA N 

42 
TABLE A2.

 

SUMMARY OF THE INCIDENCE OF NEOPLASMS IN FEMALE RATS 

FED ETHIONAMIDE IN THE DIET 

MATCHED

CONTROL 

 LOW DOSE HIGH DOSE 

ANIMALS INITIALLY IN STUDY

ANIMALS NECROPSIED AHIHALS EXAMINED HISTOPATHOLOGICALLY

 15

 15

 15

 35

 35

 35

 35 

 35 

 35 

INTEGUMENTARY SYSTEM
 

*SUBCUT TISSUE (15) (35) (35)
 

FIBROHA 1 (7X) 2 (6K) 1 (3%)
 

FIBROSARCOBA 1 (3%)
 

RESPIRATORY SYSTEM
 

ILUNG (14) (35) (35)
 

ALVEOLAR/BSONCHIOLAR ADENOMA 1 (3%)
 

OSTEOSARCOHA, METASIATIC 1 (3X)
 

HEHATOPOIETIC SYSTEM
 

*MULTIPLE ORGANS (15) (35) (35)
 

UNDIFFERENTIATED LEUKEMIA 2 (6%) 4 (11%)
 

LYMPHOCYTIC LEUKEMIA 1 (7X)
 

CIRCULATORY SYSTEM
 

NONE
 

DIGESTIVE SYSTEM
 

fLIVER (15) (35) (35)
 

HEPATOCELLOLAR ADENOMA 1 (3X) 3 (9X)
 

URINARY SYSTEM
 

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

43
 
TABLE A2. FEMALE RATS: NEOPLASMS (CONTINUED) 

MATCHED LOW DOSE HIGH DOSE 

CONTROL 

ENDOCBINE SYSTEM
 

tPITOITABY (11) (30) (32)
 

CHBOMOPHOBE ADENOMA 2 (18*) 7 (23X) 3 (9*)
 

CHBOMOPHOBE CARCINOMA 3 (10*)
 

tTHYBOID (15) (34) (34)
 

C-CELL ADENOMA 4 (12*) 3
 

C-CELL CABCINOHA 1 (7*) 1 (3*) 1 (3*)
 

BEPBODUCTIVE SYSTEM
 

*MAMMARY GLAND (15) (35) (35)
 

ADENOCARCINOMA, NOS 1 (3X)
 

FIBBOADENOHA 5 (33X) 3 (9*) 2 (6*)
 

*PREPUTIAL GLAND (15) (35) (35)

 

CABCINOHA,NOS 1 (7X)
 

ADENOMA, NOS 1 (3X)
 

tOTERUS (15) (34) (35)
 

ADENOCABCINOMA, NOS 2 (6*)
 

ENDOBETBIAL SIROHAL POLYP 5 (33X) 10 (29*) 15 (43*)
 

tOVABY (15) (34) (35)
 

FIBBOMA 1
 

NEBVOUS SYSTEM
 

NONE
 

SPECIAL SENSE OBGANS
 

'EXTERNAL EAB (15) (35) (35)
 

SQOAMOUS CELL PAPILLOHA 1 (3X)
 

*ZYHBAL'S GLAND (15) (35) (35)
 

SQUABOUS CELL PAPILLOMA 1 (3X)
 

HUSCULOSKELETAL SYSTEM
 

*BONE (15) (35) (35)
 

QSTEOSABCOMA .
 

* NUMBER OF ANIMALS WITH TISSOE EXAMINED MICROSCOPICALLY
 

* NUMBER OF ANIMALS NECROPSIED
 
TABLE A2. FEMALE RATS: NEOPLASMS (CONTINUED) 

BODY CAVITIES
 

NONE
 

ALL OTHER SYSTEMS
 

NONE
 

ANIHAL DISPOSITION SUMMARY
 

ANIMALS INITIALLY IN STUDY
 

NATURAL DEATHS
 

MORIBUND SACRIFICE
 

SCHEDULED SACRIFICE
 

ACCIDENTALLY KILLED
 

TERMINAL SACRIFICE


ANIMAL MISSING
 

INCLUDES AUTOLYZED ANIMALS
 

TUMOR SUMMARY
 

TOTAL ANIMALS HITH PRIMARY TUHOBS*
 

TOTAL PRIMARY TUMORS
 

TOTAL ANIMALS HITH BENIGH TUMORS
 

TOTAL BENIGN TUMORS
 

TOTAL ANIMALS KITH MALIGNANT TOHOBS
 

TOTAL MALIGNANT TUMORS
 

TOTAL ANIMALS HITH SECONDARY TOHORSt
 

TOTAL SECONDARY TUMORS
 

TOTAL ANIMALS HITH TUHOBS UNCERTAIN­ BENIGN OR MALIGNANT
 

TOTAL UNCERTAIN TUMORS
 

TOTAL ANIMALS HITH TUMORS UNCEBTAIH­ PRIMARY OB HETASTATIC
 

TOTAL UNCERTAIN TUMORS
 

MATCHED


CONTROL
 

15
 

1
 

2
 

 12


12
 

16
 

11
 

13
 

3
 

3
 

 LOW DOSE HIGH DOSE
 

35 35 

5 3 

5 7 

 25 25 

26 25 

35 40 

23 21 

28 31 

6 8 

7 9 

1 

1 

* PRIMAR Y TUMOBS: ALL TUMORS EXCEPT SECONDARY TOHOBS
 

t SECONDARY TUMORS: METASTATIC TUHOBS OB TUMORS HVASIVE INTO AN ADJACENT ORGAN
 

45
 

APPENDIX B
 

SUMMARY OF THE INCIDENCE OF NEOPLASMS IN
 

MICE FED ETHIONAMIDE IN THE DIET
 

47
 

TABLE B1.

 

SUMMARY OF THE INCIDENCE OF NEOPLASMS IN MALE MICE FED 

ETHIONAMIDEINTHEDIET 

MATCHED LOW DOSE HIGH DOSE 

CONTROL 

ANIMALS INITIALLY IN STUDY 15 35 34 

ANIMAL S MISSING 1 

ANIMAL S NECROPSIED 15 34 34 

ANIMAL S EXAMINE D HISTOPATHOLOGICALLY 15 34 34 

INTEGUMENTAR Y SYSTEM 

NON E 

RESPIRATOR Y SYSTEM 

tLUN G (15) (33) (34) 

ALVEOLAR/BRONCHIOLAR ADENOM A 1 (7X; 5 (15S) 1 (3X) 

ALVEOLAR/BBONCHIOLAR CARCINOM A 1 (7*) 1 (3S) 

HEMATOPOIETIC SYSTEM 

IBRAI N (15) (34) (32) 

MALIG.LYMPHOMA , HISTIOCYTIC TYPE 2 (6X) 

*TRIGEMINA L GANGLIO N (15) (34) (34) 

MALIGNAN T LYMPHOMA , MIXE D TYPE 1 (3«) 

*MULTIPLE ORGANS (15) (34) (34) 

MALIGNAN T LYMPHOHA , NOS 1 (3X) 

MALIG. LYMPHOHA , UNDIFFER-TYP E 1 (7%) 

MALIG.LYMPHOMA , LYMPHOCYTIC TYPE 1 (3X) 

HALIG. LYHPHOMA , HISTIOCYTIC TYPE 1 (7%) 6 (18XJ 

ISPLEEN (15) (34) (34) 

MALIG. LYHPHOMA , HISTIOCYTIC TYPE 1 (3») 

CIRCULATORY SYSTEM 

NON E 

DIGESTIVE SYSTEfl 

•LIVER (14) (34) (33) 

HEPATOCELLDLAR ADENOMA 1 ^1%]_ 3 J9X) 2 i6*l_ 

f NUMBER OF AHIMALS WITH TISSUE EXAMINED MICROSCOPICALLY
 

* NUMBER OF ANIMALS NECROPSIED
 

49
 
TABLE B1. MALE MICE: NEOPLASMS (CONTINUED) 

MATCHED

CONTROL 

 LOW DOSE HIGH DOSE 

HEPATOCELLULAE CARCINOMA 2 (1U%) 3 (9X) 2 (6«) 

URINARY SYSTEM 

NONE 

ENDOCRINE SYSTEM 

#THYROID

FOLLICOLAR-CELL ADENOBA

 (1<t) (31) (33) 

1 (3X) 

REPHODUCTIVE SYSTEM 

tTESTIS

INTERSTITIAL-CELL TUMOR

 (15) (32)

 1 (3X) 

 (33) 

NERVOUS SYSTEM 

NONE 

SPECIAL SENSE ORGANS 

NONE 

HUSCULOSKELETAL SYSTEM 

NONE 

BODY CAVITIES 

NONE 

ALL OTHER SYSIEHS 

__NONE 

t NUMBER OF ANIMALS WITH TISSUE EXAMINED

* NUMBER OF ANIMALS NECHOPSIED 

 MICROSCOPICALLY 

50
 
TABLE B1. MALE MICE: NEOPLASMS (CONTINUED) 

ANIHAL DISPOSITION SUMMARY
 

ANIMALS INITIALLY IN STUDY


NATURAL DEATHS


MORIBUND SACRIFICE


SCHEDULED SACRIFICE
 

ACCIDENTALLY KILLED
 

TERMINAL SACRIFICE


ANIMAL MISSING
 

3 INCLUDES AUTOLYZED ANIMALS
 

TUMOR SUMMARY
 

TOTAL ANIMALS WITH PRIMARY TUMORS*


TOTAL PHIMARY TUMORS


TOTAL ANIMALS WITH BENIGN TUMORS


TOTAL BENISN TUMORS


TOTAL ANIMALS WITH MALIGNANT TUHORS


TOTAL MALIGNANT TUMORS


TOTAL ANIMALS WITH SECONDARY TUMORS*
 

TOTAL SECONDARY TUMORS
 

TOTAL ANIMALS WITH TUMOBS UNCERTAIN­ BENIGN OR MALIGNANT
 

TOTAL UNCERTAIN TUMORS
 

TOTAL ANIMALS WITH TUMORS UNCERTAIN­ PRIMARY OR METASTATIC
 

TOTAL UNCERTAIN TUMORS
 

MATCHED
 

CONTROL
 

 15
 

6
 

8
 

1
 

7
 

7
 

2
 

2
 

5
 

5
 

LOW DOSE HIGH DOSE 

35 34 

8 6 

7 18 

1 

19 9 

1 

16 10 

20 11 

8 4 

9 14 

10 6 

11 7 

* PRIMARY TUMORS: ALL TUHORS EXCEPT SECONDARY TUMORS
 

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

51
 
TABLE B2. 

SUMMARY OF THE INCIDENCE OF NEOPLASMS IN FEMALE MICE 

FED ETHIONAMIDE IN THE DIET 

MATCHED LOW DOSE HIGH DOSE 

CONTROL 

ANIHAL S INITIALLY IH STUDY 15 35 35 

ANIHAL S HISSING 1 

ANIHALS NECBOPSIED 15 31 34 

ANIHALS EXAHINE D HISTOPATHOLOGICALLY 15 31 34 

INTEGUHBNTAR Y SYSTEM 

*SUBCOT TISSUE (15) (31) (34) 

SAHCOHA, NOS 1 (3X) _ _ ««_~.~~.~~~__«v_~__~«...___..__— ____,._.._ _____.__.___.__.__...__.______.._. ——~ — ———— — . 

HESPIRATOHY SYSIEH 

tLUN G (15) (30) (33) 

ALVEOLAR/BRONCHIOLAR ADENOM A 1 (7%) 

ALVEOLAR/BBONCHIOLAR CARCINOM A 1 (3S) 

OSTEOSARCOMA, ME1ASTATIC 1 (38) 

HEBAIOPOIBTIC SYSTEM 

*BULTIPLE ORGAN S (15) (31) (34) 

MALIGNAN T LYMPHOBA , NOS 1 (3X) 

BALIG.LYMPHOHA, UNDIFFER-TYP E 1 (3X) 2 (6%) 

BALIG.LYBPHOBA, LYMPHOCYTIC TYPE 1 (3«) 1 (3S) 

MALIG.LYMPHOMA , HISTIOCYTIC TYPE 2 (13%) 4 (12%) 

tSPLEEN (14) (31) (33) 

HEHANGIOSARCOH A 1 (7%) 

MALIG.LYHPHOBA , HISTIOCYTIC TYPE 1 (3») 

tHANDIBULA R L. NODE (12) (26 ) (30) 

HEMANGIOB A 1 (8%) 

tPANCREATIC L.NODE (12) (26) (30) 

MALIG.LYBPHOMA , ONDIFFEH-TYPE 1 (3«) 

BALIGNAN T LYMPHOMA , MIXE D TYPE 1 (455) 

fMESENTERIC L. NODE (12) (26) (30) 

HALIG.LYBPHOMA , UNDIFFER-TYP E 1 (4X j 

CIRCULATORY SYSTEM 

NONE 

t NUMBER OF ANIMALS WITH TISSUE EXAMINED MICROSCOPICALLY
 

* NUMBER OF ANIMALS NECROPSIED
 

52
 
TABLE B2. FEMALE MICE: NEOPLASMS (CONTINUED) 

MATCHED LOW DOSE HIGH DOSE
 

CONTROL
 

DIGESTIVE SYSTEM
 

tDUODENUM (14) (31) (31)
 

ADENOMATOUS POLYP, NOS 1 (3S)
 

tCOLON (15) (31) (31)
 

LEIOHYOSARCOHA 1 (3S)
 

URINARY SYSTEM
 

NOME
 

ENDOCRINE SYSTEM
 

tTHYROID (14) (31) (3U) 

FOLLICULAR-CELL ADENOMA 1 (3X) 1 (3%) 

FOLLICULAR-CELL CARCINOM A 1 (7X) 

REPRODUCTIVE SYSTEM 

fOTERUS (14) (31) (34) 

SABCOBA, NOS 1 (3%j 

tOTERUS/ENDOMETBIOH (14) (31) (34) 

ADENOMA , NOS 1 (3X) 

NERVOUS SYSTEM
 

NONE
 

SPECIAL SENSE ORGANS
 

NONE
 

MOSCULOSKELETAL SYSTEM
 

NONE
 

BODY CAVITIES
 

I NUMBER OF ANIMALS WITH TISSUE EXAMINED MICROSCOPICALLY
 

* BOHBER OF ANIMALS NECROPSIED
 

53
 
TABLE B2. FEMALE MICE: NEOPLASMS (CONTINUED)
 

MATCHED LOW DOSE HIGH DOSE
 

CONTROL
 

ALL OTHER SYSTEMS
 

HONE
 

ANIHAL DISPOSITION SUMMARY
 

ANIMALS INITIALLY IN STUDY 15 35 35
 

NATURAL DEATHS 1 5 7
 

MORIBUND SACRIFICE 4 16 7
 

SCHEDULED SACRIFICE
 

ACCIDENTALLY KILLED
 

TERMINAL SACRIFICE 10 13 21
 

ANIMAL HISSING 1
 

A INCLUDES AUTOLYZED ANIMALS
 

TUMOR SUMMARY
 

IOTAL ANIMALS WITH PRIMARY TUMORS* 4 6 14
 

TOTAL PRIMARY TUMORS 6 7 15
 

TOTAL ANIMALS WITH BENIGN TUMORS 2 2 2
 

TOTAL BENIGN TUMORS 2 2 2
 

TOTAL ANIMALS WITH MALIGNANT TUMORS 3 5 13
 

TOTAL MALIGNANT TUMORS 4 5 13
 

TOTAL ANIMALS WITH SECONDARY TUBORSt 1
 

TOTAL SECONDARY TUMORS 1
 

TOTAL ANIMALS WITH TUMORS UNCERTAIN­ BENIGN OR MALIGNANT
 

TOTAL UNCERTAIN TUMORS
 

TOTAL AHIHALS BITH TUBOBS OHCERTAIH­ PRIHARY OR METASTATIC
 

TOTAL UNCERTAIN TUMORS
 

* PRIMARY TUMORS: ALL TUMORS EXCEPT SECONDARY TOHOBS
 * SECONDARY TUHORS: METASTATIC TUMORS OR TUMORS INVASIVE INTO AN ADJACENT ORGAN
 

54
 
APPENDIX C
 

SUMMARY OF THE INCIDENCE OF NONNEOPLASTIC LESIONS
 

IN RATS FED ETHIONAMIDE IN THE DIET
 

55
 

TABLE C1.

 

SUMMARY OF THE INCIDENCE OF NONNEOPLASTIC LESIONS IN MALE RATS 

FED ETHIONAMIDE IN THE DIET 

ANIMALS INITIALLY IN STUDY
 

ANIMALS NKCROPSIED
 

ANIMALS EXAMINED HISTOPATHOLOGIC ALLY
 

INTEGUMENTARY SYSTEM
 

*SKIN
 

EPIDERMAL INCLUSION CYST
 

ULCER, NOS
 

INFLAMBAIION. SUPPURATIVE
 

*SUBCUT TISSUE
 

INFLAMMATION, CHRONIC
 

RESPIRATORY SYS1EM
 

•TRACHEA
 

INFLAMMATION, SUPPURATIVE
 

tLUNG
 

PNEUMONIA, CHRONIC MURINE
 

HEMATOPOIETIC SYSTEM
 

•SPLEEN
 

HEMORRHAGE
 

CIRCULATORY SYSTEM
 

•MYOCARDIUM
 

INFLAMMATION, INTERSTITIAL
 

DIGESTIVE SYSTEM
 

•LIVEB
 ±.a TU1?C if T &MM&1*TA nno n-L -L\f aU ^ ^ OUJTlrU£vA.LX IT DDTI D1T TV

 V Ej
 1?
 

MATCHED
 

CONTROL
 

15
 

15
 

15
 

(15)
 

(15)
 

(15)
 

U (27X)
 

(15)
 

3 (20X)
 

(15)
 

(15)
 

(15)
 

LOW DOSE HIGH DOSE
 

35	 3U
 

35	 33
 

35	 33
 

(35)	 (33)
 

1 (3*)
 

2 (6X)
 

1 (3»)
 

(35)	 (33)
 

1 (3K)
 

(35)	 (33)
 

6 (17«) 7 (21%)
 

(35)	 (33)
 « (11%) 6 (18%)
 

(34)	 (33)
 

1 (3%)
 

(35)	 (33)
 

2 (6*)
 

(35) (33)
 

t	 NUMBER OF ANIMALS WITH TISSUE EXAMINED MICROSCOPICALLY
 

* NUMBER OF ANIMALS NECROPSIED
 

55b
 
TABLE C1. MALE RATS: NONNEOPLASTIC LESIONS (CONTINUED) 

—..„* _ — —_.—­— —.—. ­—. 

MATCHED 

CONTROL 

LOW DOSE HIGHC )OSE 

INFLAMHATION, CHRONIC 

CYTOPLASMIC VACOOLIZATION 

1 

1 

(3*) 

(3X) 

*STOHACH 

ULCEB. NOS 

(15) (35) (33) 

1 (3S) 

•GASTRIC HUCOSA 

MINERALIZATION 

(15) (35) (33) 

1 (3X) 

URINARY SYSTEM 

IKIDNEY 

INFLAMMATION, CHRONIC 

(15) 

12 (SOX) 

(35) 

34 (97*) 

(33) 

33 (100X) 

EHDOCKINE SYSTEM 

NONE 

REPRODUCTIVE SYSTEM 

IPHOSTATE 

INFLAMHATION, SUPPURATIVE 

(15) (34) (33) 

3 (9%) 

ITESTIS 

INFLAMMATION, NECROTIZING 

(15) (34) 

1 (3X) 

(33) 

*EPIDIDYMIS 

GRANULOMA, SPERMATIC 

(15) (35) (33) 

1 (3%) 

NERVOUS SYSTEH 

*PERIPHERAL NERVE 

INFLAMMATION, CHRONIC 

(15) (35) 

1 (3%) 

(33) 

tBRAIN 

HEMORRHAGE 

HALACIA 

(15) 

1 (7X) 

1 (7%) 

(35) 

1 (3%) 

(30) 

1 (3») 

SPECIAL SENSE ORGANS 

*EYE 

INFLAMMATION* SUPPURATIVE 

(15) 

.

(35) 

_ 1 13*L_ . 

(33) 

1 J3J1. 

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

56
 
TABLE C1. MALE RATS: NONNEOPLASTIC LESIONS (CONTINUED) 

MATCHED LOW DOSE HIGH DOSE 

CONTROL 

*EYE/CORNEA (15) (35) (33) 

ULCEH, SOS 1 (3X) 

INFLAMMATION , CHRONIC SUPPUHATI V 2 (6%) 

MUSCULOSKELETAL SYSTEM 

*BONE (15) (35) (33)
 

FIBROUS OSTEODYSTROPHY 1 (3S) 3 (9X)
 

EXOSIOSIS 1 (3S)
 

*JOINT (15) (35) (33) 

INFLAMMATION, CHRONIC SUPPURATIV 1 (3%) 

BODY CAVITIES 

*ABDOMINAL CAVITY (15) (35) (33) 

STEATITIS 1 (7X)

 

*HESENTERY (15) (35) (33)
 

PERIARTEBITIS 3 (9%)
 

ALL OTHER SYSTEMS
 

*MOLTIPLE ORGANS (15) (35) (33)
 

MINERALIZATION 1 (3X) 5 (15X)
 

SPECIAL MORPHOLOGY SUMMARY
 

AUTOLYSIS/NO NECROPSY 1
 

* HUHBBR OF ANIMALS HITH TISSUE EXAMINED MICROSCOPICALLY
 * NUMBER OF ANIMALS NECROPSIED
 

57
 
TABLE C2. 

SUMMARY OF THE INCIDENCE OF NONNEOPLASTIC LESIONS IN FEMALE 

RATS FED ETHIONAMIDE IN THE DIET 

MATCHED LOW DOSE HIGH DOSE
 

CONTROL
 

ANIMALS INITIALLY IN STUDY


ANIMALS NECROPSIED


ANIMALS EXAMIN2D HISTOPATHOLOGICALLY


INTEGUMENTARY SYSTEM
 

•SKIN


INFLAMMATION, SUPPURATIVE


RESPIRATORY SYSTEM
 

#TRACHEA


INFLAMMATION. SUPPURATIVE


INFLAMMATION, CHRONIC SUPPURATIV


tLUNG


PNEUMONIA, CHRONIC HURINE


HEMATOPOIETIC SYSTEM
 

NONE
 

CIRCULATORY SYSJEH
 

IHYOCARDIUN


INFLAMMATION, INTERSTITIAL


DIGESTIVE SYSTEM
 

• LIVER


INFLAMMATION, CHRONIC


CYTOPLASMIC VACUOLIZATION


URINARY SYSTEM
 

fKIDNEY


HYDRQHEPHHQSIS


 15 35 35 

 15 35 35 

 15 35 35 

 (15) (35) (35) 

1 (3%) 

 (15) (34) (35) 

1 (7%) 2 (6%) 9 (26%) 

1 (3%) 

 (10) (35) (35) 

U (11%) 7 (20%) 

 (15) (35) (35) 

1 (3%) 

 (15) (35) (35) 

3 (9%) 

3 (9S) 

 (15) (35) (35) 

 i_ilSl_ 

t NUMBER OF ANIMALS WITH TISSUE EXAMINED MICROSCOPICALLY
 * NUMBER OF ANIMALS NECHOPSIED
 

58
 
TABLE C2. FEMALE RATS: NONNEOPLASTIC LESIONS (CONTINUED) 

MATCHED LOW DOSE HIGH DOSE
 

CONTROL
 

INFLAMMATION, CHEONIC 7 (47X) 26 (74X) 22 (63*)
 

ENDOCRINE SYSTEM
 

NONE
 

REPRODUCTIVE SYSTEH
 

*PHEPUTIAL GLAND (15) (35) (35)
 

INFLAMMATION, CHEONIC SUPPURATIV 1 (7%)
 

tOTERUS (15) (34) (35)
 

DECIDUAL ALTERATION, NOS 1 (7S) 1 (3X)
 

tUTEBOS/ENDOHETRIUM (15) (34) (35)
 

INFLAHMATION. SUPPDRATIVE 4 (27%) 3 (9X) 6 (17*)
 

INFLAMMATION, CHRONIC SUPPURATIV 1 (3X) 1 (3%)
 

tOVARY (15) (34) (35)
 

INFLAMHATION, SUPPORATIVE 1 (3X) 1 (3X)
 

INFLAHHATION, CH80HIC SUPPURATIV 1 (3») 1 (3«)
 

NERVOUS SYSTEM
 

NONE
 

SPECIAL SENSE ORGANS
 

*MIDDLE EAR (15) (35) (35)
 

INFLAHBATION, SUPPORATIVE 1 (3S)
 

MUSCULOSKELETAL SYSTEM
 

NONE
 

BODY CAVITIES
 

NONE
 

ALL OTHER SYSTEMS
 

# NUMBER OF ANIMALS WITH TISSUE EXAMINED MICROSCOPICALLY
 

* NUMBER OF ANIHALS NECROPSIED
 

59
 
TABLE C2. FEMALE RATS: NONNEOPLASTIC LESIONS (CONTINUED) 

MATCHED LOW DOSE HIGH DOSE 

CONTROL 

SPECIAL NOBPHOLOGY SDHMAR Y 

NO LESION REPORTED 

t HUBBEB OF ANIMALS WITH TISSUE EXAMINED MICROSCOPICALLY 

* NUMBER OF ANIMALS NECROPSIED 

60 
APPENDIX D
 

SUMMARY OF THE INCIDENCE OF NONNEOPLASTIC LESIONS
 

IN MICE FED ETHIONAMIDE IN THE DIET
 

61
 

TABLE D1.

 

SUMMARY OF THE INCIDENCE OF NONNEOPLASTIC LESIONS IN MALE 

MICE FED ETHIONAMIDE IN THE DIET 

MATCHED LOW DOSE
 

CONTROL
 

ANIMALS INITIALLY IN STUDY 15 35
 

ANIMALS MISSING 1
 

ANIMALS NECROPSIED 15 34
 

ANIMALS EXAMINED HISTOPATHOLOGIC ALLY 15 34
 

INTEGUMENTARY SYSTEM
 

*SUBCUT TISSUE (15) (34)
 

INFLAMMATION, FOCAL 1 (3%)
 

RESPIRATORY SYSIEM 

#TRACHEA

INFLAMMATION, SUPPURATIVE 

 (15) (34) 

tLUNG/BRONCHIOLE

INFLAMMATION, ACUTE SUPPURATIVE 

 (15) (33) 

*LUNG

INFLAMMATION, INTERSTITIAL 

INFLAMMATION, SUPPURATIVE 

BRONCHOPNEOHONIA SUPPURATIVE

INFLAMMATION, GR ANULOMATOUS 

 (15) 

8 (53%) 

(33) 

1

4

 (3X) 

 (12X) 

IEMATOPOIETIC SYSTEH
 

tSPLEEN (15) (34)
 

4NGIECTASIS 1 (3%)
 

HYPERPLASIA, RETICULUM CELL
 

tMESENTERIC L. NODE (13) (30)
 

LYMPHANGIECTASIS 1 (3XJ
 

CIRCULATORY SYSTEM
 

tMYOCARDIUM (15) (33)
 

INFLAMMATION^ INTERSTITIAL 2 i13%l
 

» NUMBER OF ANIMALS WITH TISSUE EXAMINED MICROSCOPICALLY
 * NOMBER OF ANIMALS NECROPSIED
 

HIGH DOSE
 

34
 

34
 

34
 

(34)
 

(34)
 

1 (3%)
 

(34)
 

1 (3S)
 

(34)
 

3 (9%)
 

16 (47%)
 

1 (3*)
 

(34)
 

2 (6*)
 

(28)
 

(33)
 

7
 

63
 
TABLE D1. MALE MICE: NONNEOPLASTIC LESIONS (CONTINUED) 

MATCHED LOW DOSE HIGH DOSE
 

CONTROL
 

DIGESTIVE SYSTEM
 

tLIVER (1U) (34) (33)
 

NECROSIS, COAGULATIVE 1 (3%)
 

HYPERPLASIA, NODOLAE 1 (7S) 1 (3X)
 

ANGIECTASIS 1 (3S)
 

URINARY SYSTEH
 

HONE
 

ENDOCRINE SYSTBH
 

tTHYHOID (14) (31) (33)
 

FOLLICOLAH CYST, NOS 1 (3X)
 

BEPHODOCTIVE SYSTEH
 

NONE
 

NERVOOS SYSTEH
 

tMEDULLA OBLONG4TA (15) (34) (32)
 

HEMORRHAGE 1 (3%)
 

SPECIAL SENSE ORGANS
 

*EAR CANAL (15) (34) (34)
 

INFLAMMATION, SUPPORATIVE 1 (3*)
 ..— — ~ _ _.~^_^_ «_^^_^_._ __ _ ___ — «. — _»__^____^—_____— _«.«,__—__________^—_ _>_ _ ._TM.^_ ___.___.
 

BUSCULOSKBLETAL SYSTEH
 

NONE
 

BODY CAVITIES
 

NONE
 

ALL OTHER SYSXEMS
 

__S9JE
 

* NUMBER OF ANIMALS BITH TISSUE EXAHINED MICROSCOPICALLY
 * NDHBER OF ANIMALS NECROPSIED
 

64
 
TABLE D1. MALE MICE: NONNEOPLASTIC LESIONS (CONTINUED) 

MATCHED LOW DOSE HIGH DOSE
 

CONTROL
 

SPECIAL MORPHOLOGY SUMMARY
 

HO LESION REPORTED 2 12
 

ANIMAL HISSING/NO NECROPSY 1
 

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

65
 
TABLE 02.

 

SUMMARY OF THE INCIDENCE OF NONNEOPLASTIC LESIONS IN FEMALE 

MICE FED ETHIONAMIDE IN THE DIET 

MATCHED LOW DOSE HIGH DOSE
 

CONTROL
 

AHIHALS INITIALLY IN STUDY 15 35 35
 

ANIMALS HISSING 1
 

AMIHALS NECROPSIED 15 31 34
 

ANIMALS EXAMINED HISTOPATHOLOGICALLY 15 31 31
 

INTEGUMENTARY SYSTEM
 

NONE
 

RESPIRATORY SYSTEH
 

•LUNG/BRONCHUS	 (15) (30) (33)
 

HYPERPLASIA, LYMPHOID 1 (3%)
 

• LONG (15) (30) (33)
 

BRONCHOPNEUMONIA, NOS 1 (3%)
 

PNEUMONIA, ASPIRATION 1 (1%)
 

INFLAMMATION, SUPPURATIVE 2 (13*)
 

BRONCHOPHEUUONIA SUPPURATIVE 8 (53%) 16 (53%) 2 (6X)
 

HYPEHPLASIA, LYMPHOID 3 (10%)
 

HEHATOPOIETIC SYSTEM
 

•BONE	 HARRO W (15) (30) (31)
 

HYELOFIBROSIS 1 (1%)
 

•SPLEEN	 (14) (31) (33)
 

HYPERPLASIA, LYMPHOID 1 (3%)
 

#MESENTEHIC L. NODE (12) (26) (30)
 

HYPEHPLASIA, LYMPHOID 1 (3%)
 

tTHYMUS (14) (29) (34)
 

HYPEHPLASIA, LYMPHOID 1 (3%)
 

CIRCULATORY SYSTEM
 

__NQNE
 

I NUMBER OF ANIMALS WITH TISSUE EXAMINED MICROSCOPICALLY
 

* NUMBER OF ANIMALS NECHOPSIED
 

66
 
TABLE 02. FEMALE MICE: NONNEOPLASTIC LESIONS (CONTINUED) 

MATCHED LOW DOSE

CONTROL 

DIGESTIVE SYSTEM 

ILIVER (15) (31)

HYPERPLASIA, NODULA R

•PANCREAS (14) (31)

INFLAMMATION , CHRONIC SUPPDRATIV 1 (7X) 

URINAR Y SYSTEM 

tKIDMEY (15) (31)


INFLABBATION, CHBONIC


tU.BLADDER/SUBBUCOSA (14) (29)


HYPERPLASIA, LYHPHOID


ENDOCRINE SYSTEH
 

NONE
 

BEPRODDCTIVE SYSXEH
 

tOTBHUS/BNDOaBTRIUn (14) (31)


INFLAMBATION. SUPPURATIVE 1 (7%) 4 (13*)


HYPEBPLASIA, CYSTIC 3 (21*) 8 (26*)


tUIEHOS/BYOHETHIOM (14) (31)


FIBROSIS 1 (7*)
 

tOVAHY (14) (31)


INFLAHMATION, NOS 1 (3X)
 

INFLABHATION, SOPPURATIVE 1 (7*) 1 (3*)


NERVOUS SYSTEM
 

NONE
 _ _ __^^»^.____v«_^_«_ ^_ _ «...__— — -. —— _-._•___•___«____*_ —— — — — _ — _~-.• — — — -.__—^


SPECIAL SENSE ORGANS
 

*HIDDLE EAR (15) (31)


jHFLAaHATigNf NQS


t NOBBEB OF ANIBALS HITH TISSUE EXABINED BICROSCOPICALLY
 * NUHBEH OF ANIBALS NECBOPSIED
 

 HIGH DOSE 

 (34) 

1 (3X) 

 (32) 

 (34)
 

1 (3*)
 

 (33)
 

1 (3*)
 

 (3*4)
 

2 (6%)
 

 14 (41*)
 

 (34)
 

 (34)
 

2 (6*)
 

— _ — • __*_^««>._.
 

 (34)
 

 11 jj*l
 

67
 
TABLE 02. FEMALE MICE: NONNEOPLASTIC LESIONS (CONTINUED) 

MATCHED LOW DOSE


CONTROL
 

INFLAMMATION, SOPPUBATIVE 1 (7%)


NOSCULOSKELETAL SYSTEM
 

NONE
 

BODY CAVITIES
 

*PERITONEUM (15) (31)


INFLAMMATION, CHRONIC SOPPURATIV 1 (7«)
 

ALL OTHER SYSTEMS
 

NONE
 

SPECIAL MORPHOLOGY SUMMARY
 

NO LESION REPORTED 5


ANIMAL MISSING/NO NECROPSY 1
 

AUTOLYSIS/NO NECROPSY 3


I NUMBER OF ANIMALS WITH TISSUE EXAMINED MICROSCOPICALLY
 * NUMBER OF ANIMALS NECROPSIED
 

 HIGH DOSE
 

1 (3«)
 

 (34)
 

6
 

1
 

68
 
APPENDIX E
 

ANALYSES OF THE INCIDENCE OF PRIMARY TUMORS
 

IN RATS FED ETHIONAMIDE IN THE DIET
 

69
 

Table El. Analyses of the Incidence of Primary Tumors in Male Rats
 

Topography: Morphology


Subcutaneous Tissue: Fibromab


P Valuesc»d


Relative Risk (Matched Control)f
 

Lower Limit
 

Upper Limit
 

Weeks to First Observed Tumor
 

Hematopoietic System: Leukemiab


P Valuesc«d


Relative Risk (Matched Control)f
 

Lower Limit
 

Upper Limit
 

Weeks to First Observed Tumor
 

Fed Ethionaraide in the Dieta
 

Matched
 

 Control
 

 0/15 (0)
 

 N.S.
 

 3/15 (20)
 

 P = 0.048(N)
 

95
 

Low High 

Dose Dose 

2/35 (6) 0/33 (0) 

N.S. N.S. 

__ 

Infinite 

0.135 

Infinite — 

— 

100 — 

5/35 (14) 1/33 (3) 

N.S. N.S. 

0.714 0.152 

0.166 0.003 

4.179 1.737 

83 99 
Table El. Analyses of the Incidence of Primary Tumors in Male Rats
 

Fed Ethionamide in the Dieta
 

(continued)
 

Hatched Low
 

Topography: Morphology Control Dose
 

Thyroid: C-cell Adenomab 3/15 (20) 2/35 (6)
 

P Valuesc»d N.S. N.S.
 

Relative Risk (Matched Control)f 0.286
 

Lower Limit 0.027
 

Upper Limit 2.289
 

Weeks to First Observed Tumor 68 104
 

Thyroid: C-cell Adenoma or
 S3 Carcinomab

 3/15 (20) 2/35 (6)
 

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

Relative Risk (Matched Control)^ 0.286
 

Lower Limit 0.027
 

Upper Limit 2.289
 

Weeks to First Observed Tumor 68 104
 

High
 

Dose
 

1/30 (3)
 

N.S.
 

0.167
 

0.003
 

1.901
 

103
 

2/30 (7)
 

N.S.
 

0.333
 

0.032
 

2.649
 

101
 
Table El. Analyses of the Incidence of Primary Tumors in Male Rats
 

Fed Ethionaraide in the Diet3
 

(continued) 

Matched Low High 

Topography; Morphology Control Dose Dose 

Testis: Interstitial-cell Tumorb 13/15 (87) 32/34 (94) 31/33 (94)
 

P Values0 >d N.S. N.S. N.S.
 

Relative Risk (Matched Control)^ 1.086 1.084
 

Lower Limit 0.908 0.905
 

Upper limit 1.315 1.315
 

Weeks to First Observed Tumor 83 83 74
 

a

Treated groups received doses of 1,500 or 3,000 ppm in feed.
 

^Number of tumor-bearing animals/number of animals examined at site (percent).
 

c

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


Armitage test when P < 0.05; otherwise, not significant (N.S.) is indicated. Beneath the
 

incidence of tumors in a treated group is the probability level for the Fisher exact test for
 

the comparison of that treated group with the matched-control group when P < 0.05; otherwise,
 

not significant (N.S.) is indicated.
 

^A negative trend (N) indicates a lower incidence in a treated group than in the control group.
 

e

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

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

group.
 
Table E2. Analyses

Topography: Morphology


Subcutaneous Tissue: Fibroma^


P Valuesc»d


Relative Risk (Matched Control)f
 

Lower Limit
 

Upper Limit
 

Weeks to First Observed Tumor


Hematopoietic System: Leukemia^


P ValuesC.d


Relative Risk (Matched Control)f
 

Lower Limit
 

Upper Limit
 

Weeks to First Observed Tumor


 of the Incidence of Primary Tumors in

Fed Ethionamide in the 

Matched Low 

 Control Dose 

 1/15 (7) 2/35 (6) 

 N.S. N.S. 

0.857 

0.050 

49.128 

 82 99 

 1/15 (7) 2/35 (6) 

 N.S. N.S. 

0.857 

0.050 

49.128 

 101 99 

 Female Rats 

Hish
 

Dose
 

1/35 (3)
 

N.S.
 

0.429
 

0.006
 

32.715
 

96
 

4/35 (11)
 

N.S.
 

1.714
 

0.196
 

81.832
 

75
 
Table E2. Analyses of the Incidence of Primary Tumors in

Fed Ethionamide in the Dieta 

(continued) 

Matched Low
 

Topography: Morphology Control Dose
 

Liver: Hepatocellular Adenoma^ 0/15 (0) 1/35 (3)
 

P Valuesc>d N.S. N.S.
 

Relative Risk (Matched Control)f Infinite
 

Lower Limit 0.024
 

Upper Limit Infinite
 

Weeks to First Observed Tumor — 104
 

Pituitary: Chromophobe Carcinomab 0/11 (0) 3/30 (10)
 

Ul 

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

Departure from Linear Trende p = 0.046
 

Relative Risk (Matched Control)^ Infinite
 

Lower Limit 0.243
 

Upper Limit Infinite
 

Weeks to First Observed Tumor — 84
 

 Female Rats 

High
 

Dose
 

3/35 (9)
 

N.S.
 

Infinite
 

0.273
 

Infinite
 

0/32 (0)
 

N.S.
 

—
 

—
 

—
 

—
 

104 
Table E2. Analyses of the Incidence of Primary Tumors in Female Rats
 

(continued)
 

Topography: Morphology


Pituitary: Chromophobe Adenoma
 

or Carcinonab


P Valuesc.d


Relative Risk (Matched Control) f
 

Lower Limit
 

Upper Limit
 

Weeks to First Observed Tumor


Thyroid: C-cell Adenoma or
 

Carcinoma*5


P Valuesc.d


Relative Risk (Matched Control)f
 

Lower Limit
 

Upper Limit
 

Weeks to First Observed Tumor


Fed Ethionamide in the Oieta 

Matched Low High 

 Control Dose Dose 

 2/11 (18) 10/30 (33) 3/32 (9) 

 N.S. N.S. N.S. 

1.833 0.516 

0.503 0.072 

15.522 5.706 

 104 82 104 

 1/15 (7) 5/34 (15) 4/34 (12) 

 N.S. N.S. N.S. 

2.206 1.765 

0.286 0.201 

100.914 84.138 

 104 104 96 
Table E2. Analyses of the Incidence of Primary Tumors in Female Rats
 

(continued)
 

Topography: Morphology
 

Mammary Gland: Fibroadenoma^
 

P Valuesc»d
 

Relative Risk (Matched Control)f
 

Lower Limit
 

Upper Limit
 

Weeks to First Observed Tumor
 

Uterus: Endometrial Stromal
 

Polypb
 

P Valuesc.d
 

Relative Risk (Matched Control)f
 

Lower Limit
 

Upper Limit
 

Weeks to First Observed Tumor
 

Fed Ethionamide in the Dieta
 

Matched


Control


5/15 (33)


P - 0.013(N)


101


5/15 (33)


N.S.


101


 Low
 

 Dose
 

 3/35 (9)
 

 P « 0.043(N)
 

0.257
 

0.048
 

1.168
 

 104
 

 10/34 (29)
 

 N.S.
 

0.882
 

0.351
 

2.823
 

 84
 

High
 

Dose
 

2/35 (6)
 

P = 0.020(N)
 

0.171
 

0.019
 

0.933
 

104
 

15/35 (43)
 

N.S.
 

1.286
 

0.571
 

3.812
 

75
 
Table E2. Analyses of the Incidence of Primary Tumors in Female Rats
 

Fed Ethionamide in the T
 

(continued)
 

Matched Low High
 

Topography: Morphology Control Dose Dose
 

Uterus: Adenocarcinoma, NOSb 0/15 (0) 0/34 (0) 2/35 (6)
 

P Valuesc»d N.S. N.S. N.S.
 

Relative Risk (Matched Control)f Infinite
 

Lower Limit 0.135
 

Upper Limit Infinite
 

Weeks to First Observed Tumor —
 __ 97
 

OO a

Treated groups received doses of 1,500 or 3,000 ppm in feed.
 

^Number of tumor-bearing animals/number of animals examined at site (percent).
 

c

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


Armitage test when P < 0.05; otherwise, not significant (N.S.) is indicated. Beneath the
 

incidence of tumors in a treated group is the probability level for the Fisher exact test for
 

the comparison of that treated group with the matched-control group when P < 0.05; otherwise,
 

not significant (N.S.) is indicated.
 

^A negative trend (N) indicates a lower incidence in a treated group than in the control group.
 

e

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

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

group.
 
APPENDIX F
 

ANALYSES OF THE INCIDENCE OF PRIMARY TUMORS
 

IN MICE FED ETHIONAMIDE IN THE DIET
 

79
 

00 

Table Fl. Analyses of the Incidence of Primary Tumors in Male Mice
 

Topography: Morphology


Lung: Alveolar/Bronchiolar
 

Adenoma or Carcinoma'1


P Valuesc,d


Relative Risk (Matched Control)f
 

Lower Limit
 

Upper Limit
 

Weeks to First Observed Tumor


Hematopoietic System:
 

Malignant Lymphomab


P Valuesc.d


Relative Risk (Matched Control)f
 

Lower Limit
 

Upper Limit
 

Weeks to First Observed Tumor


Fed Ethionamide in the Dieta
 

Matched Low
 

 Control Dose
 

 2/15 (13) 5/33 (15)
 

 N.S. N.S.
 

1.136
 

0.220
 

11.095
 

 75 83
 

 2/15 (13) 8/34 (24)
 

 N.S. N.S.
 

1.765
 

0.421
 

15.787
 

 45 89
 

High
 

Dose
 

2/34 (6)
 

N.S.
 

0.441
 

0.036
 

5.706
 

96
 

4/34 (12)
 

N.S.
 

0.882
 

0.147
 

9.103
 

94
 
Table Fl. Analyses of the Incidence of Primary Tumors in Male Mice
 

(continued) 

Topography: Morphology

Liver: Hepatocellular Carcinoma13

P Values0 » d

Relative Risk (Matched Control)^ 

Lower Limit 

Upper Limit 

Weeks to First Observed Tumor

oo 

N3 Liver: Hepatocellular Adenoma or 

Carcinomab

P Values0 >d

Relative Risk (Matched Control)f 

Lower Limit 

Upper Limit 

Weeks to First Observed Tumor

Fed Ethionamide in the Diet3
 

Matched
 

 Control
 

 2/14 (14)
 

 N.S.
 

 45
 

 3/14 (21)
 

 N.S.
 

 45
 

Low 

Dose 

High 

Dose 

3/34 (9) 2/33 (6) 

N.S. N.S. 

0.618 

0.083 

6.904 

0.424 

0.035 

5.471 

87 96 

6/34 (18) 4/33 (12) 

N.S. N.S. 

0.824 

0.215 

4.588 

0.566 

0.115 

3.496 

78 78 
Table Fl. Analyses of the Incidence of Primary Tumors in Male Mice
 

Fed Ethionamide in the Dieta
 

(continued)
 

a

Treated groups received doses of 1,000 or 2,000 ppm in feed.
 

^Number of tumor-bearing animals/number of animals examined at site (percent).
 

°Beneath the incidence of tumors in the control group is the probability level for the Cochran-


Armitage test when P < 0.05; otherwise, not significant (N.S.) is indicated. Beneath the
 

incidence of tumors in a treated group is the probability level for the Fisher exact test for
 

the comparison of that treated group with the matched-control group when P < 0.05; otherwise,
 

not significant (N.S.) is indicated.
 

^A negative trend (N) indicates a lower incidence in a treated group than in the control group.
 

QQ eThe probability level for departure from linear trend is given when P < 0.05 for any comparison.
 u>
 

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

group.
 
Table F2. Analyses of the Incidence of Primary Tumors in Female Mice
 

Fed Ethionamide in the Diet3
 

Matched Low High
 

Topography; Morphology Control Dose Dose
 

Hematopoietic System: Malignant
 

Lymphoma'3 2/15 (13) 4/31 (13) 10/34 (29)
 

P Values0>d N.S. N.S. N.S.
 

Relative Risk (Matched Control)f 0.968 2.206
 

Lower Limit 0.162 0.565
 

Upper Limit 9.933 19.069
 

Weeks to First Observed Tumor 104 89 61
 

a

Treated groups received doses of 1,000 or 2,000 ppm in feed.
 

^Number of tumor-bearing animals /number of animals examined at site (percent).
 

c

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


Armitage test when P < 0.05; otherwise, not significant (N.S.) is indicated. Beneatii the
 

incidence of tumors in a treated group is the probability level for the Fisher exact test for
 

the comparison of that treated group with the matched-control group when P < 0.05; otherwise,
 

not significant (N.S.) is indicated.
 

"A negative trend (N) indicates a lower incidence in a treated group than in the control group.
 

e

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

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

group.
 
Review of the Bioassay of Ethionamide* for Carcinogenicity
 

by the Data Evaluation/Risk Assessment Subgroup of the
 

Clearinghouse on Environmental Carcinogens
 

January 18, 1978
 

The Clearinghouse on Environmental Carcinogens was
 

established in May, 1976, in compliance with DHEW Committee
 

Regulations and the Provisions of the Federal Advisory
 

Committee Act. The purpose of the Clearinghouse is to
 

advise the Director of the National Cancer Institute (NCI)
 

on its bioassay program to identify and to 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 laboratory
 

animal sciences, 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 reports prepared on NCI-sponsored
 

bioassays of chemicals studied for carcinogenicity. It is
 

in this context that the below critique is given on the
 

bioassay of Ethionamide for carcinogenicity.
 

The primary reviewer briefly described the conditions
 

under which Ethionamide was tested and noted that the bio­ assay was conducted in the same room and at the same time
 

that other chemicals were studied. She pointed out the
 

inadequate number of control animals which resulted from
 

an undersized initial group and excessive mortality.
 Although comparisons were made with pooled control animals,
 the control data was not given in the report. The primary
 

reviewer commented on the increased but not statistically
 

significant incidence of malignant lymphomas in treated
 

mice, and in particular those associated with the central
 

nervous system. She felt that the tumors may take on
 

additional significance if compared with the program-wide
 

controls. The primary reviewer recommended that a judg­ ment on the mouse study be deferred until such an analysis
 

could be performed. Despite the shortcomings and experi­ mental limitations of the rat study, she said that it 'was
 

sufficiently adequate to conclude that Ethionamide was not
 

carcinogenic, under the conditions of test.
 

85
 
A Program staff member confirmed that the treated
 

animals were compared with pooled controls but that the data
 

were not incorporated into the report. In regard to the
 

mouse lymphomasj another Staff member commented that an
 

analysis did not show a dose-related effect. It was
 

recommended to defer any conclusion on the mouse portion
 

of the study until the Subgroup members had the opportunity
 

to review the lymphoma incidence among the pooled controls.
 

It was moved that the staff's conclusion on the rat
 

portion of the study be accepted. The motion was seconded
 

and approved by all the Subgroup members except Mr. Garfinkel,
 

who opposed it on the basis that the study was inadequate
 

due to too few animals.
 

Members Present Were:
 

Arnold Brown (Acting Chairman), Mayo Clinic
 

Lawrence Garfinkel, American Cancer Society
 

Joseph Highland, Environmental Defense Fund
 

Charles Kensler, Arthur D. Little Company
 

Verald K. Rowe, Dow Chemical, U.S.A.
 Sheldon Samuels, Industrial Union Department, AFL-CIO
 

Louise Strong, University of Texas Health Sciences Center
 

Sidney Wolfe, Health Research Group
 

* 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.
 

86 ftU.S. GOVERNMENT PRINTING OFFICE: 1978 260-899/3141 1-3 

DHEW Publication No. (NIH) 78-846