National Cancer Institute 

CARCINOGENESIS 

Technical Report Series 

No. 148 

1978 

BIOASSAY OF 

1-PHENYL-2-THIOUREA 

FOR POSSIBLE CARCINOGENICITY 

CAS No. 103-85-5 

NCI-CG-TR-148 

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

Public Health Service 

National Institutes of Health 

BIOASSAY OF
 


l-PHENYL-2-THIOUREA
 


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) 78-1704
 


REPORT ON THE BIOASSAY OF l-PHENYL-2-THIOUREA
 


FOR POSSIBLE CARCINOGENICITY
 


CARCINOGENESIS TESTING PROGRAM
 


DIVISION OF CANCER CAUSE AND PREVENTION
 


NATIONAL CANCER INSTITUTE, NATIONAL INSTITUTES OF HEALTH
 


FOREWORD: This report presents the results of the bioassay of
 


l-phenyl-2-thiourea conducted for the Carcinogenesis Testing Program,
 


Division of Cancer Cause and Prevention, National Cancer Institute
 


(NCI), National Institutes of Health, Bethesda, Maryland. This is
 


one of a series of experiments designed to determine whether selected
 


chemicals have the capacity to produce cancer in animals. Negative
 


results, in which the test animals do not have a significantly
 


greater incidence of cancer than control animals, do not necessarily
 


mean the test chemical is not a carcinogen because the experiments
 


are conducted under a limited set of circumstances. Positive results
 


demonstrate that the test chemical is carcinogenic for animals under
 


the conditions of the test and indicate a potential risk to man.
 


The actual determination of the risk to man from animal carcinogens
 


requires a wider analysis.
 


CONTRIBUTORS: This bioassay of l-phenyl-2-thiourea was conducted by
 


Litton Bionetics, Inc., Bethesda, Maryland, initially under direct
 


contract to the NCI and currently under a subcontract to Tracer
 


Jitco, Inc., prime contractor for the NCI Carcinogenesis Testing
 


Program.
 


The experimental design was determined by the NCI Project Offi­


cers, Dr. N. P. Page (1,2), Dr. E. K. Weisburger (1) and Dr. J. H.
 


Weisburger (1,3). The principal investigators for the contract were
 


Dr. S. M. Garner (4,5) and Dr. B. M. Ulland (4,5). Mr. S. Johnson
 


(4) was the coprincipal investigator for the contract. Animal treat­


ment and observation were supervised by Mr. R. Cypher (4), Mr. D. S.
 


Howard (4) and Mr. H. D. Thornett (4); Mr. H. Paulin (4) analyzed
 


dosed feed mixtures. Ms. J. Blalock (4) was responsible for data
 


collection and assembly. Chemical analysis was performed by Midwest
 


Research Institute (6) and the analytical results were reviewed by
 


Dr. N. Zimmerman (7).



Histopathologic examinations were performed by Dr. J. F. Hardisty
 


(4) at Litton Bionetics, Inc., the pathology narratives were written
 


by Dr. J. F. Hardisty (4), and the diagnoses included in this report
 


represent the interpretation of this pathologist. Histopathology
 


findings and reports were reviewed by Dr. R. L. Schueler (8).


Compilation of individual animal survival, pathology, and sum­
 mary tables was performed by EG&G Mason Research Institute (9); the
 


statistical analysis was performed by Mr. W. W. Belew (7,10) and
 


Mr. R. M. Helfand (7), using methods selected for the Carcinogenesis
 


Testing Program by Dr. J. J. Gart (11).
 


This report was prepared at METREK, a Division of The MITRE Cor­


poration (7) under the direction of the NCI. Those responsible for
 


this report at METREK are the project coordinator, Dr. L. W. Thomas
 


(7), task leader Ms. P. Walker (7), senior biologist Mr. M. Morse
 


(7), biochemist Mr. S. C. Drill (7), and technical editor Ms. P. A.
 


Miller (7). The final report was reviewed by members of the partici­


pating organizations.
 


The following other scientists at the National Cancer Institute
 


were responsible for evaluating the bioassay experiment, interpreting
 


the results, and reporting the findings: Dr. K. C. Chu (1), Dr. C.
 


Cueto, Jr. (1), Dr. J. F. Douglas (1), Dr. D. G. Goodman (1,12), Dr.
 


R. A. Griesemer (1), Dr. M, H. Levitt (1), Dr. H. A. Milman (1), Dr.
 


T. W. Orme (1), Dr. R. A. Squire (1,13), Dr. S. F. Stinson (1), Dr.
 


J. M. Ward (1), and Dr. C. E. Whitmire (1).



1.	 Carcinogenesis Testing Program, Division of Cancer Cause and
 


Prevention, National Cancer Institute, National Institutes of
 


Health, Bethesda, Maryland.
 


2.	 Now with the U.S. Environmental Protection Agency, 401 M Street
 


S.W., Washington, D.C.
 


3.	 No wit w h the Naylor Dana Institute for Disease Prevention, Amer­


ican Health Foundation, Hammon House Road, Valhalla, New York.
 


4.	 Litton Bionetics, Inc., 5516 Nicholson Lane, Kensington, Mary­


land.
 


5.	 Now with Hazleton Laboratories America, Inc., 9200 Leesburg
 


Turnpike, Vienna, Virginia.
 


6.	 Midwest Research Institute, 425 Volker Boulevard, Kansas City,
 


Missouri.
 


7.	 The MITRE Corporation, METREK Division, 1820 Dolley Madison
 


Boulevard, McLean, Virginia.
 


8.	 Tracer Jitco, Inc., 1776 East Jefferson Street, Rockville,
 


Maryland.
 


iv
 

9.	 EG&G Mason Research Institute, 1530 East Jefferson Street,
 


Rockville, Maryland.
 


10.	 Now with the Solar Energy Research Institute, Cole Boulevard,
 


Golden, Colorado.
 


11.	 Mathematical Statistics and Applied Mathematics Section, Biometry
 


Branch, Field Studies and Statistics Program, Division of Cancer
 


Cause and Prevention, National Cancer Institute, National Insti­


tutes of Health, Bethesda, Maryland.
 


12.	 Now with Clement Associates, Inc., 1010 Wisconsin Avenue, N.W.,
 


Washington, B.C.
 


13.	 Now with the Division of Comparative Medicine, Johns Hopkins
 


University, School of Medicine, Traylor Building, Baltimore,
 


Maryland.
 


SUMMARY
 


A bioassay of l-phenyl-2-thiourea for possible carcinogenicity
 


was conducted using Fischer 344 rats and B6C3F1 mice. l-Phenyl-2-thi­


ourea was administered in the feed, at either of two concentrations,
 


to groups of 50 male and 50 female animals of each species. The high
 


and low concentrations of l-phenyl-2-thiourea utilized in the chronic
 


bioassay were, respectively, 120 and 60 ppm for rats and 300 and 150
 


ppm for mice. Twenty animals of each species and sex were placed on
 


test as controls. A 78-week period of chemical administration was
 


followed by an additional observation period of 26 weeks for rats and
 


13 weeks for mice.
 


Adequate numbers of animals in all groups survived sufficiently
 


long to be at risk from late-developing tumors. Distinct dose-related
 


depression of mean body weight gain was observed in male and female
 


mice when compared with their controls, but growth retardation was not
 


observed in any dosed rat group. In addition, since no significant
 


accelerated mortality or other toxic effects were associated with the
 


dietary administration of l-phenyl-2-thiourea to rats, it is possible
 


that the compound was not administered to these animals at the maximum
 


tolerated concentrations.
 


There were no tumors in either sex of rats or mice for which a



significant positive association could be established between chemical
 


administration and tumor incidence.
 


Under the conditions of this bioassay, l-phenyl-2-thiourea was
 


not carcinogenic to Fischer 344 rats or B6C3F1 mice.
 


VII
 


TABLE OF CONTENTS
 


Page
 


I. INTRODUCTION	 1



II. MATERIALS AND METHODS	 4



A. Chemicals	 4



B. Dietary Preparation	 4



C. Animals	 5



D. Animal Maintenance	 6



E. Selection of Initial Concentrations	 7



F. Experimental Design	 9



G. Clinical and Histopathologic Examinations	 12
 


H. Data Recording and Statistical Analyses	 14
 


III. CHRONIC TESTING RESULTS: RATS	 19
 

A. Body Weights and Clinical Observations	 19
 


B. Survival	 19
 

C. Pathology 19
 

Di Statistical Analyses of Results 22
 

IV. CHRONIC TESTING RESULTS: MICE	 30
 

A. Body Weights and Clinical Observations	 30
 


B. Survival	 30
 

C. Pathology	 33
 

D.	 Statistical Analyses of Results 33
 

39
 


V.	 DISCUSSION
 


40
 


VI. BIBLIOGRAPHY
 


APPENDIX A SUMMARY OF THE INCIDENCE OF NEOPLASMS IN
 


RATS TREATED WITH l-PHENYL-2-THIOUREA A-l
 


APPENDIX B SUMMARY OF THE INCIDENCE OF NEOPLASMS IN
 


MICE TREATED WITH l-PHENYL-2-THIOUREA B-l
 


APPENDIX C SUMMARY OF THE INCIDENCE OF NONNEOPLASTIC
 


LESIONS IN RATS TREATED WITH l-PHENYL-2­


THIOUREA C-l
 

APPENDIX D SUMMARY OF THE INCIDENCE OF NONNEOPLASTIC
 


LESIONS IN MICE TREATED WITH l-PHENYL-2­


THIOUREA	 D-l
 

IX
 

LIST OF ILLUSTRATIONS 

Figure Number Page 

1 CHEMICAL STRUCTURE OF l-PHENYL-2-THIOUREA 2 

2 GROWTH CURVES FOR l-PHENYL-2-THIOUREA 

CHRONIC STUDY RATS 20 

SURVIVAL COMPARISONS OF 

CHRONIC STUDY RATS 

 l-PHENYL-2-THIOUREA 

21 

GROWTH CURVES FOR l-PHENYL-2-THIOUREA 

CHRONIC STUDY MICE 31 

SURVIVAL COMPARISONS OF 

CHRONIC STUDY MICE

 l-PHENYL-2-THIOUREA 

 32 

LIST OF TABLES 

Table Number Page 

DESIGN SUMMARY FOR FISCHER 344 RATS— 

l-PHENYL-2-THIOUREA FEEDING EXPERIMENT 10 

DESIGN SUMMARY FOR B6C3F1 MICE—l-PHENYL-2­

THIOUREA FEEDING EXPERIMENT 11 

ANALYSES OF THE INCIDENCE OF PRIMARY TUMORS 

AT SPECIFIC SITES IN MALE RATS TREATED WITH 

l-PHENYL-2-THIOUREA 23 

ANALYSES OF THE INCIDENCE OF PRIMARY TUMORS 

AT SPECIFIC SITES IN FEMALE RATS TREATED 

WITH l-PHENYL-2-THIOUREA 26 

ANALYSES OF THE INCIDENCE OF PRIMARY TUMORS 

AT SPECIFIC SITES IN MALE MICE TREATED WITH 

l-PHENYL-2-THIOUREA 34 

ANALYSES OF THE INCIDENCE OF PRIMARY TUMORS 

AT SPECIFIC SITES IN FEMALE MICE TREATED 

WITH l-PHENYL-2-THIOUREA 36 

Al SUMMARY OF THE INCIDENCE OF NEOPLASMS IN 

MALE RATS TREATED WITH l-PHENYL-2-THIOUREA A-3 
LIST OF TABLES (Concluded) 

Table Number Page 

A2 SUMMARY OF THE INCIDENCE OF NEOPLASMS IN 

FEMALE RATS TREATED WITH l-PHENYL-2-THIOUREA A-7 

Bl SUMMARY OF THE INCIDENCE OF NEOPLASMS IN 

MALE MICE TREATED WITH l-PHENYL-2-THIOUREA B-3 

B2 SUMMARY OF THE INCIDENCE OF NEOPLASMS IN 

FEMALE MICE TREATED WITH l-PHENYL-2-THIOUREA B-6 

Cl SUMMARY OF THE INCIDENCE OF NONNEOPLASTIC 

LESIONS IN MALE RATS TREATED WITH l-PHENYL2-THIOUREA C-3 

C2 SUMMARY OF THE INCIDENCE OF NONNEOPLASTIC 

LESIONS IN FEMALE RATS TREATED WITH 1-PHENYL2-THIOUREA C-8 

Dl SUMMARY OF THE INCIDENCE OF NONNEOPLASTIC 

LESIONS IN MALE MICE TREATED WITH 1-PHENYL2-THIOUREA D-3 

D2 SUMMARY OF THE INCIDENCE OF NONNEOPLASTIC 

LESIONS IN FEMALE MICE TREATED WITH l-PHENYL2-THIOUREA D-7 

XL
 


I. INTRODUCTION
 


l-Phenyl-2-thiourea (Figure 1) (NCI No. C02017) was selected for
 


bioassay by the National Cancer Institute because Of the structural
 


similarity of this compound to ethylene thiourea, a tutnorigen in hy­


brid mice (C57BL/6 x C3H/Anf and C57BL/6 x AKR) (Innes et al., 1969),
 


and the widespread oral exposure to this compound.
 


The Chemical Abstracts Service (CAS) NinthCollectiveIndex
 


(1977) name for this compound is phenylthiourea. It is also called
 


phenylthiocarbamide; 1-phenylthiourea; N-phenylthiourea; and PTU.
 


The ability to perceive the bitter taste of l-phenyl-2-thiourea
 


is genetically determined; consequently, this compound has been used
 


extensively as a test substance in genetics research and in demon­


strations of genetic polymorphism (Gosselin et al., 1976; Winchester,
 


1966). The gene responsible for l-phenyl-2-thiourea tasting ability
 


is dominant and is present in about 70 percent of the U.S. population
 


(Winchester, 1966).
 


l-Phenyl-2-thiourea is also used occasionally as a rodenticide
 


but its effectiveness in this application is limited by the compound's
 


bitter taste (Gosselin et al., 1976).
 


Specific production data for l-phenyl-2-thiourea are not avail­


able; however, this compound is produced in commercial quantities (in
 


excess of 1000 pounds or $1000 in value annually) by two U.S. compa­


nies (Stanford Research Institute, 1977).
 


*



The CAS registry number is 103-85-5.
 

II. MATERIALS AND METHODS 

A. Chemicals
 


l-Phenyl-2-thiourea was purchased from Eastman Chemical Company,
 


Rochester, New York. Chemical analysis was performed by Midwest Re­


search Institute, Kansas City, Missouri. Although the melting point
 


(149° to 150°C) was somewhat different than that reported in the lit­


erature (154°C [Weast, 1977]), the narrow range close to the reported
 


value suggested a compound of high purity. Thin-layer chromatography
 


was performed utilizing two solvent systems (chloroformrdichloro­


methane:ethyl acetate:formic acid and chloroform:acetone). Each plate
 


showed only one spot. Infrared analysis was consistent with the struc­


ture of the compound and nuclear magnetic resonance analysis was con­


sistent with that reported in the literature (Sadtler Standard Spec­


tra^) . Ultraviolet analysis yielded a ^-max of 265 nm with a molar
 


extinction coefficient of 1.45 x 10^. This value agrees quite well
 


with the value reported in the literature (1.39 x 10^) (Sadtler
 


Standard Spectra,b). The data suggest that the compound was of
 


extremely high purity. Stability studies performed by thin-layer
 


chromatography at six-month intervals indicated no degradation, as
 


detectable by the method employed.
 


Throughout this report, the term l-phenyl-2-thiourea is used to
 


represent this material.
 


B. Dietary Preparation
 


The basal laboratory diet for both dosed and control animals
 


(R)
 
 consisted of Wayne Lab-Bloxw

(Allied Mills, Inc., Chicago, Illinois).
 

l-Phenyl-2-thiourea was administered to the dosed animals as a com­


ponent of the diet.
 


The chemical was removed from its container and a proper amount
 


was blended with an aliquot of the ground feed using a mortar and
 


pestle. Once visual homogeneity was attained, the mixture was placed
 


in a 6 kg capacity Patterson-Kelley standard model twin-shell stain­


less steel V-blender along with the remainder of the feed to be pre­


pared. After 20 minutes of blending, the mixtures were placid in
 


double plastic bags and stored in the dark at 4°C. The mixture was
 


prepared once weekly.
 


The stability of l-phenyl-2-thiourea in feed was determined
 


spectrophotometrically. Ten days after preparation of diets
 


containing 60 and 120 ppm concentrations of l-phenyl-2-thiourea,
 


93 _+ 6 percent of the initial concentrations were recovered from
 


the feed.
 


C. Animals
 


Two animal species, rats and mice, were used in the carcino­


genicity bioassay. Fischer 344 rats and B6C3F1 mice were obtained
 


through contracts of the Division of Cancer Treatment, National
 


Cancer Institute. All rats and mice were supplied by Charles River
 


Breeding Laboratories, Inc., Wilmington, Massachusetts.
 


Rats and mice were approximately 4 weeks old when received.
 


Upon receipt, animals were examined for visible signs of disease or
 


parasites. Obviously ill or runted animals were culled. The re­


maining animals were quarantined for 2 weeks prior to initiation of
 


5


test. Animals which did not manifest clinical signs of disease were
 


placed on test at this time. Animals were assigned to groups and
 


distributed among cages so that the average body weight per cage was
 


approximately equal for a given species and sex.
 


D. Animal Maintenance
 


All animals were housed by species in temperature- and humidity-
 

controlled rooms. The temperature range was 22° to 26°C and the
 


relative humidity was maintained between 45 and 55 percent. Incoming
 


air was filtered through HEPA filters (Flanders Filters, McLean, Vir­


ginia) at a rate of 12 to 15 complete changes of room air per hour.
 


Fluorescent lighting was provided 8 hours per day (9:00 a.m. to 5:00
 


p.m.).
 


All rats were housed four per cage by sex and all mice five per
 


cage by sex. Throughout the study dosed and control animals of both
 


species were housed in polycarbonate cages (Lab Products, Inc., Gar­


field, New Jersey) suspended from aluminum racks. Racks were fitted
 


with a continuous stainless steel mesh lid over which a sheet of
 


filter paper was firmly secured. Filter paper was changed at 2-week
 


intervals, when the racks were sanitized. Clean cages and bedding
 


®


were provided twice weekly. Ab-sorb-dri hardwood chip bedding
 


(Wilner Wood Products Company, Norway, Maine) was used in polycar­


bonate cages for the entire bioassay.
 


Acidulated water (pH 2.5) was supplied to animals in water bot­


tles filled by an automated metering device that was checked daily
 

for diluting accuracy. Water bottles were changed twice weekly and
 


sipper tubes were washed at weekly intervals. During the period of
 


chemical administration, dosed and control animals received treated
 


or untreated Wayne Lab-Blox meal as appropriate. The feed was sup­


plied in hanging stainless steel hoppers which were refilled three
 


times per week and sanitized weekly. Food and water were available
 


ad libitum for both species.
 


All dosed and control rats were housed in a room with other
 


if



rats receiving diets containing dibutyltin diacetate (1067-33-0);
 


amitrole (61-82-5); zinc acetate (57-34-6); and copper acetate (80­


12-5).
 


All dosed and control mice were housed in a room with other
 


mice receiving diets containing Michler's ketone (90-94-8); 4,4'­


methylenebis(N,N-dimethy1)-benzenamine (101-61-1); trimethyIthiourea
 


(2489-77-2); p-chloroaniline (106-47-8); dibutyltin diacetate (1067­


33-0); 2-nitro-p-phenylenediamine (5307-14-2); 3-chloro-p-toluidine
 


(95-74-9); 5-chloro-o-toluidine (95-79-4); and N-phenyl-p-phenylene­


diamine hydrochloride (2198-59-6).



E. Selection of Initial Concentrations
 


In order to establish the maximum tolerated concentrations
 


of l-phenyl-2-thiourea for administration to dosed animals in the
 


chronic studies, subchronic toxicity tests were conducted with
 


both rats and mice. Rats were distributed among six groups, each
 


* .



CAS registry numbers are given in parentheses.
 

consisting of five males and five females. l-Phenyl-2-thiourea was
 


incorporated into the basal laboratory diet and supplied ad libitum
 


to five of the six rat groups in concentrations of 45, 70, 100, 145,
 


and 215 ppm. The sixth rat group served as a control group, receiv­


ing only the basal laboratory diet.
 


Mice were distributed among ten groups, each consisting of five
 


males and five females. l-Phenyl-2-thiourea was incorporated into
 


the basal laboratory diet and supplied ad libitum to eight of the
 


ten mouse groups in concentrations of 25, 37, 55, 80, 120, 375, 680,
 


and 810 ppm. The two remaining groups served as the control groups,
 


receiving only the basal laboratory diet.
 


The dosed dietary preparations were administered for a period
 


of 4 weeks, followed by a 2-week observation period during which all
 


animals were fed the basal diet. Individual body weights and food
 


consumption data were recorded twice weekly throughout the study.
 


Upon termination of the observation period, all survivors were sac­


rificed and necropsied.
 


At the end of the subchronic test, mean body weight gains among
 


male rats dosed with 215, 145, 100, 70 and 45 ppm were, respectively,
 


73, 72, 1, 29, and 2 percent less than the mean body weight gain of
 


their controls, while female rats receiving the same concentrations
 


displayed respective mean body weight gains of 19, 20, 2, 11 and 8
 


percent less than that of their controls. The high concentration
 

selected for administration to dosed rats in the chronic bioassay was
 


120 ppm.
 


At a dietary concentration of 810 ppm, 2 male and 2 female mice
 


died. At the end of the subchronic test, mean body weight gains among
 


male mice dosed with 810, 650, 375, and 120 ppm were, respectively,
 


3 percent less than, 3 percent more than, 3 percent more than, and 6
 


percent less than the mean body weight gain of their controls, while
 


female mice receiving the same concentrations displayed respective
 


mean body weight gains of 10 percent less than, 9 percent more than,
 


1 percent more than, and 5 percent less than that of their controls.
 


Mean body weight gains among male mice dosed with 80, 55, 37 and 25
 


ppm were, respectively, 5, 7, 4, and 1 percent greater than the mean
 


body weight gain of their controls, while female mice receiving the
 


same concentrations displayed respective mean body weight gains of
 


1, 2, 3, and 2 percent less than that of their controls. The high
 


concentration selected for administration to dosed mice in the
 


chronic bioassay was 300 ppm.
 


F. Experimental Design
 


The experimental design parameters for the chronic study (spe­


cies, sex, group size, concentrations administered, and duration of
 


treated and untreated observation periods) are summarized in Tables
 


1 and 2.
 


All rats were approximately 6 weeks old at the time the test
 


was initiated and were placed on test simultaneously. The dietary
 

TABLE 1



DESIGN SUMMARY FOR FISCHER 344 RATS
 


l-PHENYL-2-THIOUREA FEEDING EXPERIMENT
 


GROUP 

SIZE

 l-PHENYL-2-THIOUREA 

CONCENTRATION3 

TREATED 

(WEEKS)

 UNTREATED 

 (WEEKS) 

MALE 

CONTROL 20 0 0 103 

LOW DOSE 50 60 

0 

78 

26 

HIGH DOSE 50 120 

0 

78 

26 

FEMALE 

CONTROL 20 0 0 104 

LOW DOSE 50 60 

0 

78 

26 

HIGH DOSE 50 120 

0 

78 

26 

Concentrations given in parts per million. 

10
 

TABLE 2



DESIGN SUMMARY FOR B6C3F1 MICE
 


l-PHENYL-2-THIOUREA FEEDING EXPERIMENT
 


INITIAL OBSERVATION PERIOD
 


GROUP 

SIZE

 l-PHENYL-2-THIOUREA 

CONCENTRATION3 

TREATED 

(WEEKS)

 UNTREATED 

 (WEEKS) 

MALE 

CONTROL 20 0 0 91 

LOW DOSE 50 150 

0 

78 

13 

HIGH DOSE 50 300 

0 

78 

13 

FEMALE 

CONTROL 20 0 0 91 

LOW DOSE 50 150 

0 

78 

13 

HIGH DOSE 50 300 

0 

78 

13 

Concentrations given in parts per million. 

11
 

concentrations of l-phenyl-2-thiourea utilized were 120 and 60 ppm.
 


Throughout this report, those rats receiving the former concentration
 


are referred to as the high dose groups and those receiving the lat­


ter concentration are referred to as the low dose groups. Dosed rats
 


were supplied with feed containing l-phenyl-2-thiourea for 78 weeks,
 


followed by an additional observation period of 26 weeks.
 


All mice were approximately 6 weeks old at the time the test
 


was initiated, and were placed on test simultaneously. The dietary
 


concentrations of l-phenyl-2-thiourea utilized were 300 and 150 ppm.
 


Throughout this report, those mice receiving the former concentration
 


are referred to as the high dose groups and those receiving the lat­


ter concentration are referred to as the low dose groups. Dosed mice
 


were supplied with feed containing l-phenyl-2-thiourea for 78 weeks,
 


followed by an additional observation period of 13 weeks.
 


G. Clinical and Histopathologic Examinations
 


Animals were weighed immediately prior to initiation of the ex­


periment. From the first day, all animals were inspected twice daily
 


for mortality. Food consumption data were collected at monthly in­


tervals from 20 percent of the animals in each group. Body weights
 


of rats were recorded once a week for the first 6 weeks, every 2



weeks for the next 12 weeks, and at monthly intervals thereafter.
 


Body weights of mice were recorded at monthly intervals throughout
 


the bioassay.
 


12
 

All moribund animals or animals that developed large, palpable
 


masses that jeopardized their health were sacrificed. A necropsy
 


was performed on each animal regardless of whether it died, was sac­


rificed when moribund, or was sacrificed at the end of the bioassay.
 


The animals were euthanized by carbon dioxide asphyxiation, and were
 


immediately necropsied. The histopathologic examination consisted of
 


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


gross lesions taken from sacrificed animals and, whenever possible,
 


from animals found dead.
 


Tissues were preserved in a 10 percent neutral buffered formalin
 


solution, embedded in paraffin, sectioned, and stained with hematox­


ylin and eosin prior to microscopic examination.
 


Slides were prepared from the following tissues: skin, subcuta­


neous tissue, lungs and bronchi, trachea, bone marrow, spleen, lymph
 


nodes, thymus, heart, salivary gland, liver, gallbladder (mice), pan­


creas, esophagus, stomach, small intestine, large intestine, kidney,
 


urinary bladder, pituitary, adrenal, thyroid, parathyroid, testis,
 


prostate, tunica vaginalis, uterus, mammary gland, and ovary.
 


A few tissues were not examined for some animals, particularly
 


for those that died early. Also, some animals were missing, canni­


balized, or judged to be in such an advanced state of autolysis as to
 


preclude histopathologic interpretation. Thus, the number of animals
 


for which particular organs, tissues, or lesions were examined micro­


scopically varies and does not necessarily represent the number of
 


13
 

animals that were recorded in each group at the time that the test
 


was initiated.
 


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 descriptive infor­


mation on the chemicals, animals, experimental design, clinical ob­


servations, 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 transcrip­


tion and for statistical review.
 


These data were analyzed using the statistical techniques de­


scribed 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) when testing two groups for
 


equality and used Tarone's (1975) extensions of Cox's methods when
 


testing a dose-related trend. One-tailed P-values have been reported
 


14
 

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 was examined (denominator). In most instances, the denomi­


nators 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 necrop­


sied.
 


The purpose of the statistical analyses of tumor incidence is to
 


determine whether animals receiving the test chemical developed a sig­


nificantly higher proportion of tumors than did the control animals.
 


As a part of these analyses, the one-tailed Fisher exact test (Cox,
 


1970, pp. 48-52) was used to compare the tumor incidence of a control
 


group to 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, pp. 6-10) requires that the P-value for any comparison
 


be less than or equal to 0.05/k. In cases where this correction was
 


15
 

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, pp. 362-365), was also used
 


when appropriate. Under the assumption of a linear trend, this test
 


determined 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 was a positive dose re­


lationship. 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 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 pro­


cedures 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
 


16
 

during which animals died naturally or were 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 dosed group compared to its control was calculated from
 


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


is defined as p /p where p is the true binomial probability of the
 


t c t



incidence of a specific type of tumor in a treated group of animals
 


and p is the true probability of the spontaneous incidence of, the
 


c



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 analy­


ses. The interpretation of the limits is that in approximately 95
 


percent 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
 


17
 

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 (a P < 0.025
 


one-tailed test when the control incidemce 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.
 


18
 

III. CHRONIC TESTING RESULTS: RATS
 


A. Body Weights and Clinical Observations
 


No evidence of compound-related mean body weight depression was
 


apparent in either male or female rats (Figure 2).
 


No abnormal clinical signs were recorded.
 


B.	 Survival
 


The estimated probabilities of survival for male and female rats
 


in the control and l-phenyl-2-thiourea-dosed groups are shown in Fig­


ure 3. For both males and females, the Tarone test for positive asso­


ciation between dosage and mortality was not significant.
 


Adequate numbers of male rats were at risk from late-developing
 


tumors, as 86 percent (43/50) of the high dose, 82 percent (41/50) of
 


the low dose and 90 percent (18/20) of the control group survived on
 


test until the termination of the study.
 


For female rats, 78 percent (39/50) of the high dose, 74 percent
 


(37/50) of the low dose, and 80 percent (16/20) of the control group
 


survived on test until the termination of the study, thus providing
 


adequate numbers at risk from 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 C (Tables Cl and C2).



A variety of neoplastic lesions was seen with approximately
 


equal frequency	 in the control and dosed rats. The most frequently
 


19
 

750­ •750 

600 - 600 ­

I- 450­ -450 

X 

(3 

LU 

g 

§300­ -300 

CO 

150 — -150 

MALE RATS 

\ I I I ] I 

15 30 45 60 75 90 105 120 

TIME ON TEST (WEEKS) 

750 750 

- 600 

TIME ON TEST (WEEKS) 

FIGURE 2 

GROWTH CURVES FOR 1-PHENYL-2-THIOUREA CHRONIC STUDY RATS 

20 

120 
TIME ON TEST (WEEKS)

 

FIGURES 

SURVIVAL COMPARISONS OF 1-PHFNYL-2-THIOUREA CHRONIC STUDY RATS 

21 
observed neoplasm in male rats was interstitial-cell tumors of the
 


testis. A high incidence of this neoplasm is characteristic of aged
 


male Fischer 344 rats. Chromophobe adenomas of the pituitary and
 


fibroadenomas of the mammary gland were the most frequently observed
 


neoplasms in the female rats.
 


A variety of inflammatory, degenerative and proliferative lesions
 


commonly seen in aged Fischer 344 rats was seen with approximately
 


equal frequency in dosed and control animals.
 


The results of this pathologic examination indicate that 1-phenyl­


2-thiourea was not carcinogenic to male or female Fischer 344 rats
 


under the conditions of this bioassay.
 


D. Statistical Analyses of Results
 


The results of the statistical analyses of tumor incidence in
 


rats are summarized in Tables 3 and 4. The analysis is included for
 


every type of malignant tumor in either sex where at least two such
 


tumors were observed in at least one of the control or l-phenyl-2­


thiourea-dosed groups and where such tumors were observed in at least
 


5 percent of the group.
 


For female rats the Fisher exact test indicated a significantly
 


(P = 0.030) higher incidence of pituitary chromophobe adenomas in the
 


low dose group than in the control group. This result was not sup­


ported by the Cochran-Armitage test or the high dose Fisher exact
 


test and is above the P = 0.025 probability required by the Bonfer­


roni inequality.
 


22
 

TABLE 3



ANALYSES OF THE INCIDENCE OF PRIMARY TUMORS AT
 


SPECIFIC SITES IN MALE RATS TREATED WITH l-PHENYL-2-THIOUREAS



TOPOGRAPHY: MORPHOLOGY
 


Lung: Alveolar/Bronchiolar Adenoma or
 


Alveolar/Bronchiolar Carcinoma^
 


P Values0



Relative Risk (Control)
 


Lower Limit
 


Upper Limit
 


Weeks to First Observed Tumor
 


Hematopoietic System: Leukemia or
 


Malignant Lymphoma^
 


P Values0



Relative Risk (Control)
 


Lower Limit
 


Upper Limit
 


Weeks to First Observed Tumor
 


Pituitary: Chromophobe Adenoma
 


P Values0



Relative Risk (Control)
 


Lower Limit
 


Upper Limit
 


Weeks to First Observed Tumor
 


CONTROL
 


2/20(0.10)



N.S.
 


103
 


1/20(0.05)



N.S.
 
 ___.
 


87
 


2/19(0.11)



N.S.
 


103
 


LOW
 


DOSE
 


0/49(0.00)



N.S.
 


0.000
 


0.000
 


1.372
 


5/50(0.10)



N.S.
 


2.000
 


0.249
 


92.596
 


91
 


4/44(0.09)



N.S.
 


0.864
 


0.139
 


9.058
 


104
 


HIGH
 


DOSE
 


4/50(0.08)



N.S.
 


0.800
 


0.128
 


8.436
 


104
 


6/50(0.12)



N.S.
 


2.400
 


0.325
 


108.021
 


93
 


5/47(0.11)



N.S.
 


1.011
 


0.187
 


10.082
 


104
 

___ 

10 

TABLE 

TOPOGRAPHY :MORPHOLOGY
 


Adrenal: Pheochromocytoma or Pheo­


chromocytoma, Malignant"
 


P Values0



Relative Risk (Control)
 


Lower Limit
 


Upper Limit
 


Weeks to First Observed Tumor
 


Pancreatic Islets: Islet-Cell Adenoma
 


or Islet-Cell Carcinoma^
 


P Values0



Relative Risk (Control)
 


Lower Limit
 


Upper Limit
 


Weeks to First Observed Tumor
 


Testis: Interstitial-Cell Tumor
 


P Values0



Relative Risk (Control)
 


Lower Limit
 


Upper Limit
 


Weeks to First Observed Tumor
 


3 (CONTINUED) 

CONTROL
 


1/20(0.05)



N.S.
 


103
 


0/20(0.00)



N.S.
 


_—



18/20(0.90)



N.S.
 


—_



103
 


LOW
 


DOSE
 


6/48(0.13)



N.S.
 


2.500
 


0.339
 


112.370
 


104
 


2/46(0.04)



N.S.
 


Infinite
 


0.133
 


Infinite
 


104
 


43/48(0.90)



N.S.
 


0.995
 


0.872
 


1.255
 


91
 


HIGH
 


DOSE
 


2/49(0.04)



N.S.
 


0.816
 


0.046
 


47.195
 


104
 


3/46(0.07)



N.S.
 


Infinite
 


0.272
 


Infinite
 


104
 


39/49(0.80)



N.S.
 


0.884
 


0.771
 


1.186
 


89 
TABLE 3 (CONCLUDED) 


LOW HIGH 

TOPOGRAPHY: MORPHOLOGY CONTROL DOSE DOSE 

Thyroid: C-Cell Adenoma or C-Cell 

Carcinoma*5 2/19(0.11) 3/45(0.07) 2/44(0.05) 

P Values N.S. N.S. N.S. ___. Relative Risk (Control) 0.633 0.432 

Lower Limit 0.081 0.034 

Upper Limit 7.210 5.669 

Weeks to First Observed Tumor 103 104 104 

Treated groups received doses of 60 or 120 ppm in feed.
 


Number of tumor-bearing animals/number of animals examined at site (proportion).
 
 -*



"The probability level for the Cochran-Armitage test is given beneath the incidence of tumors in
 


the control group when P < 0.05; otherwise, not significant (N.S.) is indicated. The probability
 


level for the Fisher exact test for the comparison of a treated group with the control group is
 


given beneath the incidence of tumors in the treated group when P < 0.05; otherwise, not signifi­


cant (N.S.) is indicated. For both Cochran-Armitage and Fisher exact tests a negative designa­
 tion (N) indicates a lower incidence in the treated group(s) than in the control group.
 


The 95% confidence interval on the relative risk of the treated group to the control group.
 

___ 

__ _ 

TABLE 4



ANALYSES OF THE INCIDENCE OF PRIMARY TUMORS AT
 


SPECIFIC SITES IN FEMALE RATS TREATED WITH l-PHENYL-2-THIOUREA£



TOPOGRAPHY :MORPHOLOGY
 


Hematopoietic System: Leukemia or
 


Malignant Lymphoma^
 


P Values0



Relative Risk (Control)
 


Lower Limit
 


Upper Limit
 


Weeks to First Observed Tumor
 
 K>
 


Pituitary: Chromophobe Adenoma
 


P Values0



Departure from Linear Trend
 


Relative Risk (Control)
 


Lower Limit
 


Upper Limit
 


Weeks to First Observed Tumor
 


Adrenal: Pheochromocytoma or Pheo­
 chromocytoma, Malignant"
 


P Values0



Relative Risk (Control)
 


Lower Limit
 


Upper Limit
 


Weeks to First Observed Tumor
 


CONTROL
 


1/20(0.05)



N.S.
 


73
 


5/19(0.26)



N.S.
 


P = 0.014
 


98
 


3/17(0.18)



N.S.
 


103
 


LOW
 


DOSE
 


4/50(0.08)



N.S.
 


1.600
 


0.175
 


77.169
 


101
 


26/47(0.55)



P - 0.030
 


2.102
 


0.978
 


6.009
 


82
 


1/45(0.02)



N.S.
 


0.126
 


0.003
 


1.468
 


104
 


HIGH
 


DOSE
 


4/50(0.08)



N.S.
 


1.600
 


0.175
 


77.169
 


101
 


18/50(0.36)



N.S.
 


1.368
 


0.595
 


4.173
 


94
 


3/50(0.06)



N.S.
 


0.340
 


0.052
 


2.369
 


89
 

___ 

TOPOGRAPHY : MORPHOLOGY
 


Thyroid: C-Cell Adenoma or C-Cell
 


Carcinoma*3



P Values0



Relative Risk (Control)
 


Lower Limit
 


Upper Limit
 


Weeks to First Observed Tumor
 


Mammary Gland: Fibroadenoma
 


P Values0



Departure from Linear Trend
 


Relative Risk (Control)
 


Lower Limit
 


Upper Limit
 


Weeks to First Observed Tumor
 


Uterus: Endometrial Stromal Polyp
 


P Values0



Relative Risk (Control)
 


Lower Limit
 


Upper Limit
 


Weeks to First Observed Tumor
 


TABLE 4 (CONTINUED) 

CONTROL
 


1/20(0.05)



N.S.
 


—_



103
 


3/20(0.15)



N.S.
 


P = 0.022
 


—



103
 


0/18(0.00)



N.S.
 


LOW
 


DOSE
 


1/45(0.02)



N.S.
 


0.444
 


0.006
 


34.140
 


104
 


15/50(0.30)



N.S.
 


2.000
 


0.662
 


9.943
 


101
 


1/48(0.02)



N.S.
 


Infinite
 


0.021
 


Infinite
 


104
 


HIGH
 


DOSE
 


4/47(0.09)



N.S.
 


1.702
 


0.186
 


81.978
 


101
 


5/50(0.10)



N.S.
 


0.667
 


0.147
 


4.014
 


3/50(0.06)



N.S.
 


Infinite
 


0.227
 


Infinite
 


104
 


94 
00 

TABLE A (CONCLUDED) 

o



Treated groups received doses of 60 or 120 ppm in feed.
 


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


The probability level for the Cochran-Armitage test is given beneath the incidence of tumors in
 


the control group when P < 0.05; otherwise, not significant (N.S.) is indicated. The probability
 


level for the Fisher exact test for the comparison of a treated group with the control group is
 


given beneath the incidence of tumors in the treated group when P < 0.05; otherwise, not signifi­


cant (N.S.) is indicated. For both Cochran-Armitage and Fisher exact tests a negative designa­


tion (N) indicates a lower incidence in the treated group(s) than in the control group.
 


The 95% confidence interval on the relative risk of the treated group to the control group.
 


6

The probability level of the test for departure from linear trend is given beneath the control
 


group when P < 0.05.
 

No other tests for any site in either male or female rats were
 


significant. Thus, based upon these statistical results, there was
 


no conclusive evidence that l-phenyl-2-thiourea was a carcinogen in
 


Fischer 344 rats under the conditions of this bioassay.
 


To provide additional insight into the possible carcinogenicity
 


of this compound, 95 percent confidence intervals on the relative
 


risk have been estimated and entered in the tables based upon the
 


observed tumor incidence rates. In many of the intervals shown in
 


Tables 3 and 4, the value one is included; this indicates the absence
 


of statistically significant results. It should also be noted that
 


many of the confidence intervals have an upper limit greater than
 


one, indicating the theoretical possibility of tumor induction in
 


rats by l-phenyl-2-thiourea that could not be established under the
 


conditions of this test.
 


29
 

IV. CHRONIC TESTING RESULTS: MICE
 


A. Body Weights and Clinical Observations
 


Distinct dose-related mean body weight depression was apparent
 


after week 30 in both male and female mice (Figure 4).



No abnormal clinical signs were recorded.
 


B.	 Survival
 


The estimated probabilities of survival for male and female mice
 


in the control and l-phenyl-2-thiourea-dosed groups are shown in Fig­


ure 5. For both male and female mice, the Tarone test for positive
 


association between dosage and mortality was not significant.
 


Adequate numbers of male mice were at risk from late-developing
 


tumors, as 92 percent (46/50) of the high dose, 92 percent (46/50) of
 


the low dose and 85 percent (17/20) of the control group survived on
 


test until the termination of the study. One male mouse was missing
 


from the low dose group in week 12 and one was missing from the con­


trol group in week 65.
 


For female mice, 88 percent (44/50) of the high dose, 74 percent
 


(37/50) of the low dose, and 95 percent (19/20) of the control group
 


survived on test until the termination of the study, thus providing
 


adequate numbers at risk from late-developing tumors. Five low dose
 


females were missing in week 38 with three additional low dose females
 


missing in week 58.
 


30
 

TIME ON TEST (WEEKS)

 

FIGURE 4

GROWTH CURVES FOR 1-PHENYL-2-THIOUREA CHRONIC STUDY MICE 

31 
TIME ON TEST (WEEKS) 

FIGURES 

SURVIVAL COMPARISONS OF 1-PHENYL-2-THIOUREA CHRONIC STUDY MICE 

32 
C. Pathology
 


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).
 


A variety of neoplastic lesions was present in the dosed and
 


control groups. There were instances in this study where neoplastic
 


lesions occurred only, or with increased frequency, in dosed mice as
 


compared with controls. These lesions were all of types which are
 


known to occur spontaneously in B6C3F1 mice at incidences similar to
 


those observed in this study.
 


A variety of inflammatory and proliferative lesions commonly
 


seen in B6C3F1 mice occurred with approximately equal frequency in
 


dosed and control mice.
 


The results of this pathologic examination indicate that under
 


the conditions of this study, dietary administration of l-phenyl-2­


thiourea was not carcinogenic to B6C3F1 mice of either sex.
 


D. Statistical Analyses of Results
 


The results of the statistical analyses of tumor incidence in
 


mice are summarized in Tables 5 and 6. The analysis is included for
 


every type of malignant tumor in either sex where at least two such
 


tumors were observed in at least one of the control or l-phenyl-2­


thiourea-dosed groups and where such tumors were observed in at least
 


5 percent of the group.
 


33
 

___ 

___ 

___ 

TABLE 5



ANALYSES OF THE INCIDENCE OF PRIMARY TUMORS AT
 


SPECIFIC SITES IN MALE MICE TREATED WITH l-PHENYL-2-THIOUREA£



TOPOGRAPHY : MORPHOLOGY
 


Lung: Alveolar /Bronchiolar Adenoma or
 


Alveolar/Bronchiolar Carcinoma^
 


P Values0



Relative Risk (Control)
 


Lower Limit
 


Upper Limit
 


Weeks to First Observed Tumor
 


Hematopoietic System: Leukemia or
 


Malignant Lymphoma^
 


P Values0



Relative Risk (Control)
 


Lower Limit
 


Upper Limit
 


Weeks to First Observed Tumor
 


Liver: Hepatocellular Adenoma or
 


Hepatocellular Carcinoma'3



P Values0



Relative Risk (Control)
 


Lower Limit
 


Upper Limit
 


Weeks to First Observed Tumor
 


CONTROL
 


3/19(0.16)



N.S.
 


91
 


1/19(0.05)



N.S.
 


91
 


1/19(0.05)



N.S.
 


83
 


LOW
 


DOSE
 


6/49(0.12)



N.S.
 


0.776
 


0.191
 


4.463
 


91
 


5/49(0.10)



N.S.
 


1.939
 


0.243
 


89.722
 


87
 


7/48(0.15)



N.S.
 


2.771
 


0.401
 


121.980
 


91
 


HIGH
 


DOSE
 


6/49(0.12)



N.S.
 


0.776
 


0.191
 


4.463
 


91
 


2/50(0.04)



N.S.
 


0.760
 


0.043
 


43.961
 


91
 


3/49(0.06)



N.S.
 


1.163
 


0.103
 


59.809
 


91
 

TABLE 5 (CONCLUDED) 

a



Treated groups received doses of 150 or 300 ppm in feed.
 


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


The probability level for the Cochran-Armitage test is given beneath the incidence of tumors in
 


the control group when P < 0.05; otherwise, not significant (N.S.) is indicated. The probability
 


level for the Fisher exact test for the comparison of a treated group with the control group is
 


given beneath the incidence of tumors in the treated group when P < 0.05; otherwise, not signifi­


cant (N.S.) is indicated. For both Cochran-Armitage and Fisher exact tests a negative designa­


tion (N) indicates a lower incidence in the treated group(s) than in the control group.
 


The 95% confidence interval on the relative risk of the treated group to the control group.
 


uo
 


Ul
 

___ 

___ 

TABLE 6



ANALYSES OF THE INCIDENCE OF PRIMARY TUMORS AT
 


SPECIFIC SITES IN FEMALE MICE TREATED WITH l-PHENYL-2-THIOUREA
 


TOPOGRAPHY: MORPHOLOGY
 


Lung: Alveolar/Bronchiolar Carcinoma
 


P Values0



Relative Risk (Control)
 


Lower Limit
 


Upper Limit
 


Weeks to First Observed Tumor
 


Lung: Alveolar/Bronchiolar Adenoma or
 


Alveolar/Bronchiolar Carcinoma**
 


P Values0



Relative Risk (Control)
 


Lower Limit
 


Upper Limit
 


Weeks to First Observed Tumor
 


Hematopoietic System: Leukemia or
 


Malignant Lymphoma*"
 


P Values0



Relative Risk (Control)
 


Lower Limit
 


Upper Limit
 


Weeks to First Observed Tumor
 


CONTROL
 


0/19(0.00)



N.S.
 


0/19(0.00)



N.S.
 


——



3/20(0.15)



N.S.
 


74
 


LOW
 


DOSE
 


0/40(0.00)



N.S.
 


_ _—



3/40(0.07)



N.S.
 


Infinite
 


0.298
 


Infinite
 


91
 


6/42(0.14)



N.S.
 


0.952
 


0.233
 


5.450
 


88
 


HIGH
 


DOSE
 


3/49(0.06)



N.S.
 


Infinite
 


0.243
 


Infinite
 


85
 


5/49(0.10)



N.S.
 


Infinite
 


0.511
 


Infinite
 


85
 


5/50(0.10)



N.S.
 


0.667
 


0.147
 


4.014
 


71
 

TABLE 6 (CONCLUDED)
 


LOW HIGH
 


TOPOGRAPHY: MORPHOLOGY CONTROL DOSE DOSE
 


Liver: Hepatocellular Adenoma or
 


Hepatocellular Carcinoma^ 0/19(0.00) 0/39(0.00) 4/48(0.08)



P Values0 N.S. N.S. N.S.
 


Relative Risk (Control) Infinite
 


Lower Limit 0.383
 


Upper Limit Infinite
 


Weeks to First Observed Tumor 91
 


Treated groups received doses of 150 or 300 ppm in feed.
 


w Number of tumor-bearing animals/number of animals examined at site (proportion).
 
 Q



The probability level for the Cochran-Armitage test is given beneath the incidence of tumors in
 


the control group when P < 0.05; otherwise, not significant (N.S.) is indicated. The probability
 


level for the Fisher exact test for the comparison of a treated group with the control group is
 


given beneath the incidence of tumors in the treated group when P < 0.05; otherwise, not signifi­


cant (N.S.) is indicated. For both Cochran-Armitage snd Fisher exact tests a negative designa­


tion (N) indicates a lower incidence in the treated group(s) than in the control group.
 


The 95% confidence interval on the relative risk of the treated group to the control group.
 

None of the statistical tests for any site in mice of either sex
 


indicated a significant positive association between the administra­


tion of l-phenyl-2-thiourea and an increased tumor incidence. Thus,
 


at the dose levels used in this experiment, there was no evidence
 


that l-phenyl-2-thiourea was a carcinogen in B6C3F1 mice.
 


To provide additional insight into the possible carcinogenicity
 


of this compound, 95 percent confidence intervals on the relative
 


risk have been estimated and entered in the tables based upon the
 


observed tumor incidence rates. In many of the intervals shown in
 


Tables 5 and 6, the value one is included; this indicates the absence
 


of statistically significant results. It should also be noted that
 


many of the confidence intervals have an upper limit greater than
 


one, indicating the theoretical possibility of tumor induction in
 


mice by l-phenyl-2-thiourea that could not be established under the
 


conditions of this test.
 


38
 

V. DISCUSSION
 


Adequate numbers of animals in all groups survived sufficiently
 


long to be at risk from late-developing tumors. Distinct dose-related
 


depression of mean body weight gain was obserVed in male and female
 


mice when compared with their controls, but growth retardation was not
 


observed in any dosed rat group. In addition, since no significant
 


accelerated mortality or other toxic effects were associated with the
 


dietary administration of l-phenyl-2-thiourea to rats, it is possible
 


that the compound was not administered to these animals at the maximum
 


tolerated concentrations.
 


No neoplasms in either sex of either species occurred for which
 


a significant positive association between chemical administration
 


and tumor incidence could be established. All observed neoplasms
 


were of types and incidences known to occur spontaneously in Fischer
 


344 rats or B6C3F1 mice.
 


Under the conditions of this bioassay, l-phenyl-2-thiourea was
 


not carcinogenic to Fischer 344 rats or B6C3F1 mice.
 


39
 

VI. BIBLIOGRAPHY
 


Armitage, P., Statistical Methods in Medical Research, Chapter 14.
 


J. Wiley & Sons, New York, 1971.
 


Berenblum, I., editor, Carcinogenicity Testing. International Union
 


Against Cancer, Technical Report Series, Vol. 2. International
 


Union Against Cancer, Geneva, 1969.
 


Chemical Abstracts Service, The Chemical Abstracts Service (CAS)
 


Ninth Collective Index, Volumes 76-85, 1972-1976. American
 


Chemical Society, Washington, B.C., 1977.
 


Cox, D.R., Analysis of Binary Data, Chapters 4 and 5. Methuen and
 


Co., Ltd., London, 1970.
 


Cox, D.R., "Regression Models and Life-Tables." Journal of the Royal
 


Statistical Society, Series "B" 34:187-220, 1972.
 


Gart, J.J., "The Comparison of Proportions: A Review of Significance
 


Tests, Confidence Limits, and Adjustments for Stratification."
 


International Statistical Institute Review 39:148-169, 1971.
 


Gosselin, R.E., H.C. Hodge, R.P. Smith, and M.N. Gleason, Clinical
 


Toxicology of Commercial Products, 4th edition. The Williams
 


and Wilkins Company, Baltimore, Maryland, 1976.
 


Innes, J.R.M., B.M. Ulland, M.G. Valeric, L. Petrucelli, L. Fishbein,
 


E.R. Hart, A.J. Pallotta, R.R. Bates, H.L. Falk, J.J. Gart, M.
 


Klein, I. Mitchell, and J. Peters, "Bioassay of Pesticides and
 


Industrial Chemicals for Tumorigenicity in Mice: A Preliminary
 


Note." Journal of the National Cancer Institute 42(6):1101-1114,
 


1969.
 


Kaplan, E.L. and P. Meier, "Nonparatnetric Estimation from Incomplete
 


Observations." Journal of the American Statistical Association
 


53_:457-481, 1958.
 


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


"Carcinogenesis Bioassay Data System." Computers and Biomedical
 


Research 7:230-248, 1974.
 


Miller, R.G., Simultaneous Statistical Inference. McGraw-Hill Book
 


Co., New York, 1966.
 


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by Different Numbers of Administration of Benzo (a) Pyrene and
 


Ferric Oxide." Cancer Research 32:1073-1079, 1972.
 


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U.S.A. Menlo Park, California, 1977.
 


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Weast, R.C., editor, CRC Handbook of Chemistry and Physics, 58th edi­


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41
 


APPENDIX A



SUMMARY OF THE INCIDENCE OF NEOPLASMS
 


IN RATS TREATED WITH l-PHENYL-2-THIOUREA
 


TABLE Al 

SUMMARY OF THE INCIDENCE OF NEOPLASMS IN MALE RATS TREATED WITH l-PHENYL-2-THIOUREA 

CONTROL(UMTR ) LOW DOSE HIGH DOSE 

11-1035 11-1033 11- 1031 

ANIMALS INITIALL Y IN STUDY 20 50 50 

ANIMALS NECROPSIED 20 50 50 

ANIMAL S EXAMINE D HISS COPATHOLOGICALLY** 20 49 50 

INTEGUMENTAR Y SYSTEM 

*SUBCUT TISSUE (20) (50) (50)
 


PHEOCHROMOCYTOMA, METASTATIC 1 (2*)
 


SARCOMA, NOS 1 (5X)
 


FIBROMA 1 (5X) 1 (2*)
 


FIBROSARCOMA 1 (2*) 1 (2X)
 


LIPOMA 1 (5*)
 


FIBROADENOMA 1 (2X)
 


RESPIRATOR Y SYSTEM 

#LUNG (20) (<»9) (50) 

ALVEOLAR/BRONCHIOLAR ADENOM A 2 (10% ) 2 

ALVEOLAR/BRONCHIOLAR CARCINOM A 2 (US) 

C-CELL CARCINOMA , METASTATIC 1 (2X) 1 (2%) 

HEMATOPOIETIC SYSTEM 

*MULTIPLE ORGAN S (20) (50) (50) 

MALIGNAN T LYMPHOMA , NOS 1 (2X) 

LEUKEMIA , NOS 3 (6S) 3 (6X) 

LYMPHOCYTIC LEUKEMI A 1 (2X) 

ERYTHROCYTIC LEUKEMI A 1 (2X) 1 (2X) 

#SPLEEN (20) («7) (U9 ) 

MALIG . LYMPHOMA , HISTIOCYTIC TYPE 1 (5X) 

#LIVER (20) (U8) (50)
 


LEUKEMIA, NOS 1 (295)
 


CIRCULATORY SYSTEM
 


__ NONE __________________________________________________________________
 


* NUMBER OF ANIMAL S WITH TISSUE EXAMIBE D MICR3SCOPICALL Y * NUMBER OF ANIMALS NECROPSIED 

**EXCLUDES PARTIALLY AUTOLYZED ANIMALS 

A-3 
TABLE A1 (CONTINUED) 

CONTROL(UNTR ) LOW DOSE HIGH DOSE 

11-1035 11-1033 11-1031 

DIGESTIV E SYSTE M 

#LIVEB 

HEPATOCELLULA R ADEN3M A 

NEOPLASTIC NODUL E 

URINAR Y SYSTE M 

NON E 

ENDOCRIN E SYSTEM 

#PITUITAP Y 

CHROMOPHOB E ADENOM A 

#ADRENA L 

PHEOCHROMOCYTOM A 

PHEOCHPOMOCYTOMA , MALIGNAN T 

*THYROI D 

C-CELL ADENOM A 

C-CELL CARCINOM A 

#PANCFEATI C ISLETS 

ISLET-CELL ADENOM A 

ISLET-CELL CARCINOM A 

REPRODUCTIV E SYSTE M 

*MAMMAR Y GLAN D 

FIBROADENOM A 

#TESTIS 

INTEPSTITIAL-CELL TUMO R 

NERVOU S SYSTE M 

NON E 

SPECIAL SENS E ORGAN S 

NON E 

* NUMBE R OF ANIMAL S WITH TISSUE 

* NUMBE R OF ANIMAL S NECROPSIE D 

(20) 

(48) 

1 

1 

(19 ) (Ui» ) 

2 (11% ) 14 

(20) (48) 

1 (5%) 5 

1 

(19) (45) 

1 (5%) 2 

1 (5*) 1 

(20) (46) 

2 

(20) (50) 

1 (5%) 

(20) (48) 

18 (90«) 43

 EXAMINE D MICROSCOPICALL Y 

 (2X) 

 (2X ) 

 (9X) 

 (10*) 

 (2X) 

 (M) 

 (2X ) 

 (436) 

 (90%) 

(50) 

1 (2X) 

(47) 

5 (11% ) 

(49) 

2 (4«) 

(44) 

1 (2%) 

1 (23C) 

(46) 

2 (4«) 

1 (2«) 

(50) 

1 (2%) 

(49) 

39 (8055) 

A-4 
TABLE A1 (CONTINUED) 

C3NTROL(UNTR ) LOW DOSE HIGH DOSE 

11-1035 11-1033 11-1031 

MUSCULOSKELETAL SYSTEM 

NONE 

BODY CAVITIES 

*ABDOMINAL CAVIT Y (20) (50) (50) 

MESOTHELIOMA, NOS 1 (2%) 

*TUNICA VAGINALIS (20) (50) (50) 

MESOTHELIOMA, NOS 1 (2%) 

ALL OTHEB SYSTEMS
 


*MULTIPLE ORGANS (20) (50) (50)
 


FIBROSARCOMA 1 (2J5)
 


ANIMAL DISPOSITION SUMMARY
 


ANIMALS INITIALLY IN STUDY 20 50 50
 


NATURAL DEATHS 1 6 4



MORIBUND SACRIFICE 1 3 3



SCHEDULED SACRIFICE
 


ACCIDENTALLY KILLED
 


TERMINAL SACRIFICE 18 <*1 U3
 


ANIMAL MISSING
 


# NUMBER OF ANIMALS WITH TISSUE EXAMINED MICROSCOPICALLY
 


* NUMBER OF ANIMALS NECROPSIED
 


A-5
 

TABLE Al (CONCLUDED)
 


CONTROL (UNTR ) LOW DOSE HIGH DOSE 

1 1-1035 11-1033 11-1031 

TO BOS SUMMARY
 


TOTAL ANIMALS HITH PRIMARY TUMORS* 19
 

TOTAL PRIMARY TUMORS 30
 

TOTAL ANIMALS WITH BENIGN TUMORS 18
 

TOTAL BENIGN TUMORS 27
 

TOTAL ANIMALS WITH MALIGNANT TUMORS 3
 

TOTAL MALIGNANT TUMORS 3
 

TOTAL ANIMALS WITH SECONDARY TUMORS*
 

TOTAL SECONDARY TUMORS
 

TOTAL ANIMALS WITH TUMORS UNCERTAIN­


BENIGN OR MALIGNANT
 

TOTAL UNCERTAIN TUMORS
 

TOTAL ANIMALS WITH TUMORS UNCERTAIN­


PRIMARY OR METASTATIC
 


TOTAL UNCERTAIN TUMORS
 


* PRIMARY TUMORS: ALL TUMORS EXCEPT SECONDARY TUMORS
 


 47 45
 


 68 67
 


 45 42
 


 58 54
 


9 11
 


9 11
 


2 1



2 1



1 2



1 2



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


A-6
 

TABLE A2 

SUMMARY OF THE INCIDENCE OF NEOPLASMS IN FEMALE RATS TREATED WITH l-PHENYL-2-THIOUREA 

1:ONTROL(UNTR ) L OW DOSE HIGH DOSE 

11-1036 1 1-1034 11-1 032 

ANIMALS INITIALLY IN STUDY 20 50 50 

ANIMALS NECROPSIED 20 50 50 

ANIMALS EXAMINE D HIS1 [^PATHOLOGICALLY** 20 50 50 

INTEGUMENTARY SYSTEM
 


*SKIN (20) (50) (50)
 


SQUAMOUS CELL CARCINOMA 1 (236)
 


*SUBCUT TISSUE (20) (50) (50)
 


CYSTADENOMA, NOS 1 (235)
 


SARCOMA, NOS 2 (4)5)
 


FIBROMA 2 (436) 1 (2)5)
 


RESPIRATORY SYSTEM
 


#LUNG (19) (50) (50) 

CARCINOMA , NOS, METASTATIC 1 (5«) 1 (2)5) 

C-CELL CARCINOMA , METASTATIC 1 (235) 

PHEOCHROMOCYTOMA, METASTATIC 1 (5)5) 

HEMATOPOIETIC SYSTEM 

*MULTIPLE ORGAN S (20) (50) (50) 

MALIGNAN T LYMPHOMA , NOS 1 (235) 2 (435) 

MALIG.LYMPHOMA , HISTIOCYTIC TYPE 1 (535) 

LEUKEMIA,NO S 2 (4)5) 1 (2%) 

tMEDIASTINAL L.NODE (17) (41) (41) 

MALIGNAN T LYMPHOMA, NOS 1 (235) 

tLIVEF (20) (18) (49) 

LEUKEMIA,NO S 1 (2%)

CIRCULATORY SYSTEM 

JJOfiE. 

* NUMBER OF ANIMAL S WITH TISSUE EXAMINE D MICROSCOPICALL Y 

* NUMBER OF ANIMAL S NECROPSIED 

**EXCLUDES PARTIALLY AUTOLYZED ANIMALS 

A-7 
TABLE A2 (CONTINUED) 

DIGESTIV E SYSTE M 

#SMAL L INTESTIN E 

ADENOCARCINOMA , NO S 

JRINAP Y SYSTE M 

NON E 

ENDOCRIN E SYSTE M 

#PITUITAR Y 

CHBOMOPHOB E ADENOM A 

#ADRFNA L 

ADENOMA , NO S 

PHEOCHROMOCYTOM A 

PHEOCHPOHOCYTOHA , MALIGNAN T 

#THYROI D 

C-CELL ADENOM A 

C-CELL CARCINOM A 

REPRODUCTIV E SYSTE M 

*MAMMAP Y GLAN D 

FIBROADENOM A 

HEMANGIOM A 

*CLITORA L GLAN D 

SQUAMOU S CELL CARCINOM A 

SEBACEOU S ADENOM A 

# UTERU S 

SARCOMA , NO S 

ENDOMSTPIA L STROMA L POLY P 

*OVAF Y 

SEPTOLI-CELL TUMOR 

NERVOU S SYSTE M 

NON E 

# NtlHBF E O F ANIMAL S WIT H TISSUE 

* NUMBE R O F ANIMAL S NECROPSIE D 

CONTROL(UMTR ) LOW DOSE 

1 1-1036 11-1034 

(20) 

(45) 

1 (2%) 

(19) (47) 

5 (26% ) 26 (55*) 

(17) (45) 

1 (2% ) 

2 

1

 (12%) 

 (6% ) 

1 (2X) 

(20 ) (45) 

1 (5X) 1 (2X) 

1 (5% ) 

(20) (50) 

3 (15%) 15 (30X) 

1 (2X ) 

(20) (50) 

1 (2%) 

(18) (48) 

1 (2S) 

(18) (45) 

 EXAMINE D MICROSCOPICALL Y 

HIGH DOSE 

11-1032 

(49) 

(50) 

18 (36%) 

(50) 

3 (6%) 

(47) 

2 (4% ) 

2 (4«) 

(50) 

5 (10%) 

(50) 

1 (2X) 

(50) 

2 (4%) 

3 (6X) 

(47) 

1 (2%) 

A-8 
TABLE A2 (CONTINUED)

 

CONTROL(UNTH )LOW DOSE

11-1036 11-1034

SPECIAL SENSE ORGAN S 

*ZYMBAL' S GLAN D(20) (50)

EPITHELIAL TUMOR, NOS, BENIG N 1 (5% ) 

MUSCULOSKELETA L SYSTEM 

NONE 

BOD Y CAVITIES 

NONE 

A LL OTHER SYSTEMS 

ADIPOSE TISSUE 

LIPOM A 1 

ANIMA L DISPOSITION SUMMAR Y 

ANIMAL S INITIALLY IN STUD Y20 50 

NATURA L DEATHS 2 5 

MORIBUN D SACRIFICE 2 8 

SCHEDULED SACRIFICE 

ACCIDENTALL Y KILLED 

TERMINAL SACRIFICE16 37


ANIMAL MISSING 


I_IfiCL2DES_AUTOLYZED_ANIMALS 

# NUMBE R OF ANIMAL S WIT H TISSUE EXAMINE D MICROSCOPICALL Y 

* NUMBE R OF ANIMAL S NECROPSIED 

 HIGH DOSE 

 11-1032 

 (50) 

 50 

4 

7 

 39 


A-9 
TABLE A2 (CONCLUDED)
 


CONTROL (CNTR) LOW DOSE HIGH DOSE 

11-1036 11-1034 11-1032 

TUMOR SUMMAR Y 

TOTAL ANIMAL S WITH PRIMAR Y TUMORS * 12 37 30 

TOTA L PRIMAR Y TUMORS 15 59 42 

TOTAL ANIMAL S WIT H BENIG N TUMOR S 10 34 26

 

TOTAL BENIG N TUMOR S 12 50 34

 

TOTAL ANIMAL S WIT H MALIGNAN T TUMORS 3 9 3 

TOTAL MALIGNAN T TUMORS 3 9 8 

TOTAL ANIMAL S WITH SECONDAR Y TUMORSt 2 2

TOTAL SECONDAR Y TUMORS 2 2

TOTAL ANIMAL S WITH TUMORS UNCERTAIN ­

BENIGN OR MALIGNAN T 

TOTAL UNCERTAI N TUMORS 

TOTAL ANIMAL S WITH TUMORS UNCERTAIN­

PRIMAR Y OR METASTATIC 

TOTAL UNCERTAI N TUMORS 

* PPIMARY TUMORS: ALL TUMORS EXCEPT SECONDARY TUMORS
 


* SECONDARY TUMORS: METASTATIC TUMORS OB TUMORS INVASIVE INTO AN ADJACENT ORGAN
 


A-10
 

APPENDIX B



SUMMARY OF THE INCIDENCE OF NEOPLASMS
 


IN MICE TREATED WITH l-PHENYL-2-THIOUREA
 


TABLE Bl 

SUMMARY OF THE INCIDENCE OF NEOPLASMS IN MALE MICE TREATED WITH l-PHENYL-2-THIOUREA 

CONTROL(UNTR) LOW DOSE 

22-2035 22-2033 

ANIMAL S INITIALLY IN STUDY 20 50 

ANIMALS HISSING 1 1 

ANIMALS NECROPSIED 19 49 

ANIMAL S EXAMINED HISTO PATHOLOGICALLY** 19 49 

INTEGDHENTARY SYSTEM 

*SOBCUT TISSUE (19) (49) 

SARCOMA, NOS 1 (2*) 

RESPIRATORY SYSTEM 

*LUNG (19) (49) 

ALVEOLAR/BRONCHIOLAR ADENOM A 3 (16X) 5 (10X) 

ALVEOLAR/BRONCHIOLAR CARCINOMA 1 (2*) 

HEMATOPOIETIC SYSTEM 

*MOLTIPLE ORGAN S (19) (49) 

MALIGNAN T LYMPHOMA, NOS 2 (4*) 

LEUKEMIA,NOS 1 (2*) 

UNDIFFERENTIATED LEUKEMI A 1 (2%) 

*LYMPH NODE (13) (34) 

MALIGNANT LYMPHOMA, NOS 1 (8*) 1 (3*) 

•MESENTERIC L. NODE (13) (34) 

MALIGNANT LYMPHOMA, NOS 

CIRCULATORY SYSTEM 

NONE 

DIGESTIVE SYSTEM
 


tLIVER (19) (48) 

fi_J13lL 

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

**EXCLUDES PARTIALLY AUTOLYZED ANIMALS 

HIGH DOSE 

22-2031 

50 

50 

50 

(50) 

(49) 

5 (10«) 

1 (2X) 

(50) 

1 (2«) 

(32) 

(32) 

1 (35J) 

(49) 

3_i6*j_­

B-3
 

TABLE Bl (CONTINUED) 

CONTROL(UNTR) LOW DOSE HIGH DOSE 

22-2035 22-2033 22-2031 

HEPATOCELLULAR CARCINOMA 1 (2%) 

HEMANGIOM A 1 (2%) 1 (2«) 

#SMALL INTESTINE (19) (23) (48) 

ADENOMA , NOS 1 (556) 

URINAR Y SYSTEM 

NONE 

ENDOCRIN E SYSTEM 

NONE 

REPRODUCTIVE SYSTEM 

NON E 

NERVOUS SYSTEM
 


NONE
 


SPECIAL SENSE ORGANS
 


NONE
 


MUSCULOSKELETAL SYSTEM
 


NONE
 


BODY CAVITIES
 


NONE
 


ALL OTHER SYSTEMS
 


NONE
 


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


B-4
 

TABLE Bl (CONCLUDED)
 


CONTROL(UNTR ) LOW DOSE HIGH DOSE 

22-2035 22-2033 22-2031 

ANIMA L DISPOSITION SUMMAR Y 

ANIMAL S INITIALLY IN STUDY 20 50 50

 

NATURA L DEATHS 2 2 3

MORIBUN D SACRIFICE 1 1 

SCHEDULED SACRIFICE 

ACCIDENTALL Y KILLED 

TERMINA L SACRIFICE 17 46 U6 

ANIMAL MISSING 1 1 

9 INCLUDES AUTOLYZE D ANIHAL S 

TUMO R SUMMAR Y 

TOTAL ANIMAL S WITH PRIMAR Y TUMORS* 6 16 12

 

TOTAL PRIMAR Y TUMORS 6 20 12

 

TOTAL ANIMAL S WITH BENIG N TUMORS 5 11 9 

TOTAL BENIG N TUMORS 5 12 9 

TOTAL ANIMALS WITH MALIGNANT TUMORS 1 8 3



TOTAL MALIGNANT TUMORS 1 8 3



TOTAL ANIMALS WITH SECONDARY TUMORS*
 


TOTAL SECONDARY TUMORS
 


TOTAL ANIMALS WITH TUMORS UNCERTAIN­


BENIGN OR MALIGNANT
 


TOTAL UNCERTAIN TUMORS
 


TOTAL ANIMALS WITH TUMORS UNCERTAIN­


PRIMARY OR METASTATIC
 


TOTAL UNCERTAIN TUMOHS
 


* PRIMARY TUMORS: ALL TUMORS EXCEPT SECONDARY TUMORS
 


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


B-5
 

TABLE B2 

SUMMARY OF THE INCIDENCE OF NEOPLASMS IN FEMALE MICE TREATED WITH l-PHENYL-2-THIOUREA 

CONTROL(UNTR ) LOW DOSE HIGH DOSE 

22-2036 22-2034 22-2032 

ANIMAL S INITIALLY IN STUDY 20 50 50

 

ANIMAL S MISSIN G 8

ANIMAL S NECROPSIED 20 42 50

 

ANIMAL S EXAMINE D HISTOPATHOLOGIC ALL Y ** 20 41 50

 

INTEGUMENTAR Y SYSTEM 

NONE 

RESPIRATOR Y SYSTEM 

#LONG (19) (40) (49) 

ALVEOLAR/BRONCHIOLAR ADENOMA 3 (8J6) 2 (4*) 

ALVEOLAR/BRONCHIOLAR CARCINOMA 3 (6X) 

HEMATOPOIETIC SYSTE M 

*MOLTIPLE ORGAN S (20) (42) (50) 

MALIGNAN T LYMPHOMA , NO S 2 (10X ) 4 (10X) 2 (4X) 

LEUKEMIA , NOS 1 (5X) 1 <2X ) 3 (6X) 

tSPLEE N (18) (40) (46)

 

HEMANGIOM A 1 (6*)

 

#LIVF<? (19) (39) (48)

 

MALIGNAN T LYMPHOMA , NO S 2 (5X)

 

CIRCULATOR Y SYSTE M 

NON E 

DIGESTIV E SYSTEM 

#LIVER (19) (39) (48) 

HEPATOCELLULAR ADENOMA 3 (6X) 

HEPA1QCJEL.LJLM_C.MCII!OM.A.. 

# NUMBE R OF ANIMAL S WITH TISSUE EXAMINE D MICROSCOPICALL Y 

* NUMBE R OF ANIMAL S NECROPSIED 

**EXCLUDES PARTIALLY AUTOLYZED ANIMALS 

B-6 
TABLE B2 (CONTINUED) 

CONTROL(ONT8 ) LOW DOSE HIGH DOSE 

22-2036 22-2034 22-2032 

URINAR Y SYSTEM 

tURINARY BLADDER (19) (41) (47) 

LIPOMA 1 (5X) 

HEMANGIOSARCOM A 1 (2X) 

ENDOCRINE SYSTEM 

• PITUITARY (16) (31) (30)
 


CHROMOPHOBE ADENOMA 1 (3S)
 


REPRODUCTIVE SYSTEM
 


#OTER!JS (20) (41) (50)
 


LEIOMYOMA 1 (2%)



tOVARY (16) (33) (45)
 


TERATOMA, NOS 1 (3%)



NERVOUS SYSTEM
 


NOME
 


SPECIAL SENSE ORGANS
 


NONE
 


MUSCULOSKELETAL SYSTEM
 


NONE
 


BODY CAVITIES
 


*ABDOHINAL CAVITY (20) (42) (50)
 


LIPOMA 1 (235)
 


ALL OTHER SYSTEMS
 


_J!2NE.
 


t NUMBER OF ANIMALS WITH TISSUE EXAMINED MICROSCOPICALLY
 


* NUMBER OF ANIMALS NECROPSIED
 


B-7
 

TABLE B2 (CONCLUDED) 

CONTROL(UNTR )

22-2036

 LOW DOSE 

 22-2034 

HIGH DOSE 

22-2032 

ANIMA L DISPOSITION SUMMAR Y 

ANIMAL S INITIALL Y IN STUDY 

NATURA L DEATHS 

MORIBUN D SACRIFICE 

SCHEDULE D SACRIFICE 

ACCIDENTALL Y KILLED 

TERMINA L SACRIFICE 

ANIMA L MISSING 

20 

19 

50 

37 

50 

44 

9 INCLUDES AUTOLYZE D ANIMAL S 

TUMO R SUMMAR Y 

TOTAL ANIMAL S WITH PRIMAR Y

TOTAL PRIMAR Y TUMORS

 TUMORS* 4 

5 

11 

14 

15 

15 

TOTAL ANIMALS 2 

TOTAL BENIG N TUMORS 2 5 6 

 WITH BENIGN TUMORS 6 4 

 ANIMAL S 3

TOTAL MALIGNAN T TUMORS 3 8 9 

TOTAL ANIMAL S WIT H SECONDAR Y TOMORS # 

TOTAL SECONDAR Y TUMORS 

TOTAL ANIMAL S WIT H TUMORS UNCERTAIN ­

BENIG N OP MALIGNAN T 1

TOTAL UNCERTAI N TUMORS 1

TOTAL ANIMAL S WITH TUMORS UNCERTAIN ­

PRIMAR Y OR METASTATIC 

TOTAL UNCERTAIN TUMORS 

* PRIMAR Y TUMORS : ALL TUMOR S EXCEPT SECONDAR Y TUMORS 

* SECONDAR Y TUMORS : METASTATIC TUMOPS OR TUMORS INVASIV E INTO AN ADJACENT ORGA N 

TOTAL WITH MALIGNAN T TUMORS 6 9 

B-8 
APPENDIX C



SUMMARY OF THE INCIDENCE OF NONNEOPLASTIC
 


LESIONS IN RATS TREATED WITH l-PHENYL-2-THIOUREA
 


TABLE Cl

 

SUMMARY OF THE INCIDENCE OF NONNEOPLASTIC LESIONS IN MALE RATS 

TREATED WITH l-PHENYL-2-THIOUREA 

CONTHOL(UNTR ) LOW DOSE HIGH DOSE 

11-1035 11-1033 11 -1031 

ANIMALS INITIALLY IB STODT 20 50 50 

ANIMALS NECROPSIED 20 50 50

 

ANIMAL S EXAHINE D HISTOPATHOLOGICAL!,!** 20 49 50

 

INTEGUMENTARY STSTEH
 


*SKIN (20) (50)
 (50)
 


EPIDERMAL INCLUSION CYST 1 (2*)
 


RESPIRATORY SYSTEH
 


#LONG (20) (1*9)
 (50)
 


EDEHA, NOS 1 (2*)
 


INFLAMHATION, INTERSTITIAL 2 (4*)
 


PNEUMONIA, LIPID
 1 (2X)
 


PNEUMONIA. CHRONIC MURINE 1 (5X) 11 (22i)
 12 (24«)
 


PNEUMONIA INTERSTITIAL CHRONIC
 2 (XX)
 


HYPERPLASIA, ADENOMATOUS 1 (5*) 2 (4*)
 2 (4X)
 


HEMATOPOIETIC SYSTEM
 


tBONE MARROH (19)
 (43)
 


MYELOSCLEROSIS 1 (5X)
 


tSPLEEN (20) (47)
 (49)
 


CONGESTION, NOS 1 (2Jt)
 1 (2«)
 


HEHOSIDEROSIS 5 (25%) 8 (17X)
 5 (10X)
 


HEMATOPOIESIS U (20%) 3
 5 (10*)
 


#SPLENIC RED PULP (20) (47)
 (49)
 


DEPLETION 1 (2%)



#BESENTERIC L. NODE (18) (45)
 (40)
 

HYPEHPLASIA, LYMPHOI D 1 (3*)
 

CIRCULATORY SYSTEH
 


#HEART (20) (49)
 (49) 

# NUHBER OF ANIMALS WITH TISSUE EXAMINED MICROSCOPi:ALLY 

* NUHBER OF ANIMAL S NECROPSIED 

**EXCLUDES PARTIALLY AUTOLYZED ANIMALS 

C-3 
TABLE Cl (CONTINUED)
 


CONTROL(UNTR ) LOW DOSE HIGH DOSE 

11-1035 11-1033 11-1031 

fMYOCARDIU M (20) (49) (49) 

INFLAMMATION , NOS 1 (2X) 

INFLAMMATION , CHRONIC 1 (2X) 

FIBROSIS 3 (6*) 1 (2X) 

FIBROSIS, FOCAL 1 (2%) 

DEGENERATION , NOS 5 (25%) 11 (22*) 12 (24X) 

DIGESTIVE SYSTEM 

#LIVER (20) (48) (50) 

CYST, NOS 1 (5%) 

DEGENERATION , NOS 1 (2X) 

NECROSIS, NOS 1 (2*) 

METAMORPHOSIS FATTY 2 (10S) 1 (2*) 1 (2%) 

BASOPHILIC CYTO CHANG E 1 (5%) 5 (10*) 1 (2X) 

CLEAR-CELL CHANG E 1 (2*) 1 (2X) 

HEPATOCYTOMEGAL Y 1 (2X) 2 (4X) 

# LIVER/CENTRILOBULA R (20) (48) (50)

 

CONGESTION, NOS 1 (2*)

 

#LIVER/PERIPORTAL (20) (48) (50)

 

FIBROSIS 1 (2*)

 

#BILE DUCT (20) (48) (50)

 

INFLAMMATION , NOS 1 (2X) 

HYPERPLASIA , NOS 2 (10K ) 10 (2U) 7 (14X)

 

#PANCREA S (20) (46) (46) 

FIBROSIS 1 (2X) 

FIBROSIS, DIFFUSE 1 (2*) 1 (2X) 

NECROSIS, FAT 1 (2*) 

ATROPHY , FOCAL 1 (2*) 

# STOMACH (20) (47) (50) 

HYPERPLASIA , ADENOMATOU S 1 (2X) 

#SMAL L INTESTIN E (20) (46) (49) 

HYPERPLASIA , LYMPHOI D 2 (435)

 

#LASGE INTESTINE (20) (47) (49)

7 NEMlflBIASIS. _ 2 J1Q21 _J.2_126*_1 I1§£L _ 

# NUMBER OF ANIMALS WITH TISSUE EXAMINED MICROSCOPICALLY
 


* NUMBER OF ANIMALS NECROPSIED
 


C-4
 

TABLE Cl (CONTINUED) 

CDNTROL(UNTR ) LOW DOSE HIGH DOSE 

11-1035 11-1033 11-1031 

URINAR Y STSTEH 

*KIDNEY 

INFLAHBATION, NOS 

INFLAMMATION , CHRONIC 

CALCINOSIS, NOS 

PIGMENTATION, NOS 

LIPOHATOSIS 

#KIDNEY/TUBULE 

BASOPHILIC CYTO CHANG E 

#KIDNEY/PELVIS 

HYPERPLASIA , EPITHELIAL 

ENDOCRINE SYSTEM 

•PITUITARY 

CYST, NOS 

#PITUITARY/BASOPHIL 

HYPERPLASIA, NOS 

HYPERPLASIA, FOCAL 

IADRENA L 

HEHORRHAGIC CYST 

HETAMORPHOSIS FATTY 

CYTOLOGIC DEGENERATION 

HYPERPLASIA , NOS

 

*ADRENAL CORTEX 

HYPERPLASIA, NOS

 

•ADRENA L MEDULLA 

HYPERPLASIA, NOS 

#THYROID 

PIGMENTATION, NOS 

GOITER COLLOID 

HYPERPLASIA, C-CELL 

HYPERPLASIA, FOLLICULAR-CELL 

#PANCPEATIC ISLETS 

BIP.EBms.IA* NOS 

NUMBER OF ANIMALS HITH TISSUE 

NUMBER OF ANIMAL S NECROPSIED 

(20) (49) 

1 (5X) 1 (235) 

12 (60%) 29 (59X) 

1 (5X) 3 (6S) 

1 (2X) 

(20) (49) 

(20) (49) 

1 (5X) 

(19) (1*4) 

1 (5%) 

(19) 

(44) 

1 (2X) 

1 (2X) 

(20) 

(48) 

1 (5X) 

1 (2X) 

1 <2J) 

(20) 

(48) 

(20) (48) 

5 (25*) 7 (15X) 

(19) 

(45) 

1 (5*) 4 (9S) 

5 (11X ) 

(20) (46) 

. 1_l2iL 

 EXAMINE D MICROSCOPICALLY 

(50) 

1 (2X) 

21 (42«) 

1 (2«) 

4 (8X) 

(50) 

2 (4X) 

(50) 

(47) 

(47) 

1 (2X) 

(49) 

1 (2S) 

(49) 

1 (2X) 

(49) 

7 (14X) 

(44) 

4 (9X) 

1 (2X) 

2 (5S) 

1 (2X) 

(46) 

C-5 
TABLE Cl (CONTINUED) 

CONTROL(ONTR ) LOW DOSE HIGH DOSE 

11-1035 11-1033 11-1031 

REPRODUCTIVE SYSTEM 

*HAMMAR Y GLAN D (20) (50) (50) 

ABSCESS, NOS 1 (2X) 

#PROSTATE (20) (HH) («7) 

HYPERPLASIA , EPITHELIAL 1 (5X) 

#TESTIS (20) (l»8) (49) 

ATROPHY , NOS 2 (10%) 2 (US) 1 (2*) 

NERVOU S SYSTEM 

IBRAI N (20) (U7) (50) 

HEMORRHAG E 1 (2%)

SPECIAL SENSE ORGANS 

NONE 

MOSCOLOSKELETA L SYSTEM 

NONE 

BODY CAVITIES 

*ABDOMINA L CAVITY (20) (50) (50) 

STEATITIS 1 (2») 

*PERITONEO M (20) (50) (50) 

INFLAMMATION, FOCAL GRANOLOHATO U 1 (2X) 

*PLEUR A (20) (50) (50) 

FOAM-CELL 1 (2X) 

A L L OTHER SYSTEMS 

ADIPOSE TISSUE 

t NUHBER OF ANIMAL S WITH TISSUE EXAMINE D MICROSCOPICALLY 

* NUHBE R OF ANIMAL S NECROPSIE D 

06 
TABLE Cl (CONCLUDED) 

CONTRO L (UNTR ) LOW DOSE HIGH DOSE 

11-1035 11-1033 11-1031 

SPECIAL MORPHOLOGY SUMMAR Y 

HO LESION REPORTED 

AUTO/NECROPSY/HISTO PEHF 1 

AOTO/NECROPSY/NO HISTO 1 

f NUMBER OF ANIHAL S WITH TISSUE EXAMINE D MICROSCOPICALLY 

* NUMBER OF ANIMAL S NECROPSIED 

C-7 
TABLE C2

 

SUMMARY OF THE INCIDENCE OF NONNEOPLASTIC LESIONS IN FEMALE RATS 

TREATED WITH l-PHENYL-2-THIOUREA

 

CONTROL(UNTR ) LOW DOSE HIGH DOSE 

11-1036 11-1034 11-1032 

ANIMALS INITIALL Y IN STUDY 20 50 50 

ANIMAL S NECROPSIED 20 50 50 

ANIMAL S EXAMINE D HISTOPATHOLOGIC ALLY** 20 50 50 

INTEGUMENTAR Y SYSTE M 

NON E 

RESPIRATOR Y SYSTE M 

#L'JNG (19) (50) (50)
 


THROMBOSIS, NOS 1 (2Jt)
 


HEMORRHAGE 1 (2%)



INFLAMMATION, INTERSTITIAL 1 (2%)



PNEUMONIA, LIPID 1 (2«)
 


PNEUMONIA, CHRONIC MDRINE 1 (5X) 9 (18J6) 14 (28%)
 


PNEUMONIA INTERSTITIAL CHRONIC 2 (11%)
 


GRANULOMA, NOS 1 (2%)



LIPOGRANULOMA 2 (4X)
 


GRANULOMA, FOREIGN BODY 1 (28)
 


FOAM-CELL 1 (2JS) 1 (23S)
 


HYPERPLASIA, ADENOMATOUS 1 (2%)
 


HEMATOPOIETIC SYSTEM 

fBON E MARRO W (17 ) (43) (45) 

OSTEOSCLEROSIS 1 (2%) 

fSPLEEN (20) (47) (48)
 


CONGESTION, NOS 2 (4X)
 


HEMOSIDEROSIS 6 (30%) 10 (2U) 7 (15X)
 


ERYTHROPHAGOCYTOSIS 1 (2%)



HYPERPLASIA, LYMPHOID 1 (2%) 1 (2%)



HEMATOPOIESIS 6 (3055) 10 (2U) 4



#CERVICAL LYMPH NODE (17) (41) (41)
 


1_J2|L_­


# NUMBER OF ANIMAL S WITH TISSUE EXAMINED MICROSCOPICALLY 

* NUMBE R OF ANIMAL S NECROPSIE D 

**EXCLUDES PARTIALLY AUTOLYZED ANIMALS 

C-8
 

TABLE C2 (CONTINUED)

 

CIRCULATORY SYSTEM 

#HYOCARDIU H 

FIBROSIS 

FIBROSIS, FOCAL 

DEGENERATION , NOS 

DIGESTIVE SYSTEM 

#SALIVAR Y GLAN D 

INFLAMMATION, NOS 

#LI7ER 

HEMORRHAG E 

NECROSIS, NOS 

NECROSIS, FOCAL 

METAMORPHOSI S FATTY 

BASOPHILIC CYTO CHANG E 

EOSINOPHILIC CYTO CHANG E 

HYPERPLASIA , LYMPHOI D 

#HEPATIC CAPSULE 

HEMORRHAGIC CYST 

#LIVER/PERIPORTAL 

INFLAMMATION , CHRONIC 

tBILE DUCT 

DILATATION , NOS 

HYPERPLASIA , NOS 

#PANCREAS 

FIBROSIS 

ATROPHY , FOCAL 

#SMALL INTESTINE 

PARASITISM 

HYPERPLASIA , LYMPHOI D 

#LARGE INTESTINE 

NEMATODIASI S 

#COLON 

f NUMBER OF ANIMAL S HITH TISSUE

* NUMBE R OF ANIMAL S NECROPSIE D 

CONTROL (UNTR ) LOW DOSE 

11-1036 11-1034 

(19) (47) 

1 (5X) 10 (2U) 

(17) (44)

 

(20) (48) 

1 (2X) 

1 (5X) 1 (2X) 

2 (10X) 3 (6X) 

5 (25%) 13 (27X ) 

1 (2%) 

(20) (48) 

1 (5X) 

(20) (48) 

(20) (48)

 

1 (2X) 

1 (5X ) 2 <«) 

(19) (47) 

1 (5X) 

1 (5%)

(20) (45) 

2 (4% ) 

(20) 

(46) 

4 (20X) 9 (2055) 

(20) (46) 

 EXAMINE D MICROSCOPICALL Y 

HIGH DOSE 

11-1032 

(49) 

1 (2X) 

1 (2X) 

15 (31X) 

(48) 

1 (2%) 

(49) 

1 (2X) 

3 (6X) 

15 (3U) 

1 (2X) 

(49) 

(49) 

1 (2X) 

(49) 

1 (2X) 

4 (8X) 

(48) 

1 (2X) 

(49)

1 (2«) 

1 (2X) 

(44) 

9 (20%) 

(44) 

C-9 
TABLE C2 (CONTINUED)

 

C3HTROL(UNTR) LOW DOSE HIGH DOSE 

11-1036 11-1034 11-1032 

URINARY SYSTEM
 


tKIDNEY (18) (47) (50)
 


GLOMERULONEPHRITIS, NOS 1 (28)
 


GLOMESULONEPHEITIS, MEHBRANOUS 1 (2X)
 


INFLAMMATION, CHRONIC 4 (22%) 18 (38X) 28 (56%)



NEPHROSIS, NOS 2 (435)
 


PIGMENTATION, NOS 2 (11*) 6 (13X) 2 (4X)
 


tURINARY BLADDER (15) (40) (40)
 


HYPERTROPHY, NOS 1 (3X)
 


HYPERPLASIA, EPITHELIAL 1 (3X)
 


ENDOCRIN E SYSTEM 

#PITUITAR Y (19) (47) (50) 

RETENTION FLUID 1 (2%) 

CYST, NOS 1 (5X) 5 (1U) 5 (10X) 

#ADRENA L (17) (45) (50)

 

CYST, NOS 1 (2X)

 

LIPOIDOSIS 2 (4X) 

#ADRENA L CORTEX (17) (45) (50)

 

CYST, NOS 1 (2%)

HEMORRHAGI C CYSt 1 (6X) 1 (2X)

 

HYPERPLASIA , NODULA R 1 (2X)

 

HYPERPLASIA, NOS 1 (2X) 1 (2X)

 

HYPERPLASIA , FOCAL 1 (2%)

#ADHENA L MEDULL A (17) (45) (50)

 

HYPERPLASIA, NOS 3 (18%) 4 (9XJ 4 (8X)

 

#THYROID (20) (45) (47) 

PIGMENTATION , NOS 1 (2J5) 

HYPERPLASIA, FOCAL 1 (5*) 

HYPERPLASIA , C-CELL 2 (10*) 6 (13*) 1 (2%) 

HYPERPLASIA, FOLLICULAR-CELL 1 (2X) 1 (2X) 

REPRODUCTIV E SYSTE M 

*«AMMAR Y GLAN D (20) (50) (50) 

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


C-10
 

TABLE C2 (CONTINUED) 

CONTROL (UNTR) LOW DOSE HIGH DOSE 

11-1036 11- 1034 11-1032 

ADENOSIS 1 (5X) 2 (435)

 

LACTATION 1 (2X)

 

#UTERU S (18) (48) (50) 

HYDROMETRA 1 (2%) 

ABSCESS, NOS 1 (2X) 

ICERVIX UTERI (18) (48) (50) 

ABSCESS, NOS 1 (2%) 

DEGENERATION, HUCOID 1 (6*) 

#UTERU S/ENDOM ET RIUM (18) (48) (50) 

CYST, NOS 1 (2%) 

INFLAMMATION, NOS 1 (6*) 

ABSCESS, NOS 

HYPERPLASIA, NOS 1 (2X) 

HYPERPLASIA, CYSTIC 1 (2X) 2 (4%) 

#OVARY (18) (45) (47) 

CYST, NOS 1 (6X) 1 (235) 

FOLLICULAR CYST, NOS 1 (2*) 

PAROVARIA N CYST 1 (2%) 2 

CONGESTION, NOS 1 (235) 

NERVOUS SYSTEM 

tBRAIN (20) (49) (49)
 


HYDROCEPHALUS, NOS 1 (5*) 1 (2«)
 


HEMORRHAGE 1 (2%)
 


ATROPHY, NOS 1 (28)
 


ATROPHY, PRESSURE 1 (535) 1 (2%) 2 (4%)
 


SPECIAL SENSE ORGANS
 


*EAR (20) (50) (50) 

EPIDERMA L INCLUSION CYST 1 (2«) 

MUSCULOSKELETAL SYSTEM 

NONE 

— — — — — — — — — — —— — — — — ^— ^— — — ——-. — — — — — — —•— ^— •— — — — — — _———•— . — «, — ———• « — _ — •«_ — _ — _ — ____«.«,_____ _ 

BODY CAVITIES 

*PLEUPA (20) (50) (50) 

____ EQAM-CELL. ____________________________________________ 

# NUMBER OF ANIMALS WITH TISSUE EXAMINED MICROSCOPICALLY 

* NUMBER OF ANIMAL S NECROPSIED 

C-ll 
TABLE C2 (CONCLUDED)
 

CDNTROL(UNTR ) LOW DOSE HIGH DOSE 

11-103 6 11-1034 11-1032 

*M£SENTEB Y (20) (50) (50) 

NECROSIS, FAT 1 (555) 

A LL OTHEP SYSTEMS 

*MULTIPL E ORGAN S (20) (50) (50) 

PIGMENTATION , NOS 1 <5K ) 2 (UX) 

SPECIAL MORPHOLOGY SUMMAFY 

NO LESION REPORTED 

# NUMBE R OF ANIMAL S WITH TISSUE EXAMINE D MICROSCOPICALL Y 

* NUMBE R OF ANIMAL S NECROPSIE D 

C-12 
APPENDIX D



SUMMARY OF THE INCIDENCE OF NONNEOPLASTIC
 


LESIONS IN MICE TREATED WITH l-PHENYL-2-THIOUREA
 


TABLE Dl

 

SUMMARY OF THE INCIDENCE OF NONNEOPLASTIC LESIONS IN MALE MICE 

TREATED WITH l-PHENYL-2-THIOUREA

 

CONTRO L (OtJTR) LOW DOSE HIGH DOSE 

22-2035 22-2033 22-2031 

ANIMALS INITIALLY IN STUDY 20 50 50 

ANIMALS HISSING 1 1

ANIMALS NECROPSIED 19 49 50

 

ANIBALS EXAMINE D HISTOPATHOLOGICALLY** 19 49 50 

INTEGUMENTARY SYSTEM 

*SKIN (19)
 (49)	 (50)
 

CYST, NOS 1 (2%)
 

*SUBCUT TISSUE
 (19)
 (49)	 (50)
 


INFLAMMATION ACTIVE CHRONIC
 1 (2*)
 


RESPIRATORY SYSTEM
 


#LUNG/BPONCHUS
 (19)
 (49) (49)
 


HYPERPLASIA, EPITHELIAL
 1	 (5X)
 


•LUNG/BRONCHIOLE
 	 (19)
 (49) (49)
 


INFLAMMATION, NOS
 1 (5%)
 


INFLAMMATION, ACUTE
 1 (5X)
 


tLUNG (19)(49)

 (49) 

THROMBUS, ORGANIZED 1 (255) 

EDEMA, NOS 1 (5%) 1 (2X) 2 (4%) 

HEMOBRHAG E 1 (2%) 

PNEUMONIA, ASPIRATION 1 (255) 

PNEUMONIA , CHRONIC MURIN E 1 <2X ) 2 (14%) 

PERIVASCULAR CUFFING 1 (2%) 3 (6%) 

FOAM-CELL 1 (2%)

 

HYPERPLASIA, ADENOMATOUS 1 (2%)

EPITHELIAL1ZATION 1 (2%) 

HEMATOPOIETIC SYSTEM
 


tSPLEEN
 	 (19)
 (47) (46) 

f NUMBER OF ANIMAL S WITH TISSUEEXAMINE D MICROSCOPICALL Y 

* NUMBER OF ANIMALS NECROPSIED 

**EXCLUDES PARTIALLY AUTOLYZED ANIMALS 

D-3 
TABLE Dl (CONTINUED)
 


HIGH DOSE 

22-2031 

(49) 

2 (4*) 

(44) 

2 (5X) 

(49) 

1 (2*) 

1 (2%) 

2 (4*) 

(47) 

1 (2«) 

(48) 

(48) 

1 (2*) 

(49) 

1 (2%) 

3 (6S) 

4 (8X) 

(49) 

CIRCULATOR Y SYSTE M 

t MYOCARDIU M 

DEGENERATION , NOS 

DIGESTIVE SYSTEM 

tSALIVARY GLAN D 

PERIVASCULA R CUFFIN G 

#LIVE H 

HEHOBRHAGIC CYST 

INFLAMMATION , ACUTE FOCAL 

PERIVASCULAR CUFFIN3 

NECROSIS , NOS 

METAMORPHOSI S FATTY 

BASOPHILIC CYTO CHANG E 

tSTOMAC H 

INFLAMMATION , ACUTE SUPPURATIV E 

#SMAL L INTESTIN E 

HYPERPLASIA, LYMPHOID 

*LARGE INTESTINE 

NEMATODIASI S 

URINAR Y SYSTEM 

#KIDNE Y 

HYDRONEPHROSI S 

PYELONEPHRITIS , NOS 

INFLAMMATION , CHRONIC 

PERIVASCULA R CUFFIN G 

tKIDNEY/PELVI S 

HEMORRHAG E 

ENDOCRIN E SYSTEM 

NON E 

CONTRO L (UNTR ) 

22-2035 

(19) 

(17) 

1 (6%) 

(19 ) 

2 (11*) 

1 (5X) 

(19) 

(19) 

(19) 

U (21% ) 

(19) 

3 (16*) 

2 (11% ) 

(19 ) 

LOW DOSE 

22-2033 

(1*8) 

1 (2%) 

(45) 

3 (7%) 

(48) 

4 (8S) 

1 (2X) 

1 (2X) 

1 (2*) 

1 (2X) 

(45) 

(23) 

1 (4*) 

(43) 

5 (12X ) 

(48) 

1 (2%) 

8 (17*) 

14 (29X ) 

(48) 

1 (2%) 

# NUMBER OF ANIMALS WITH TISSUE EXAMINED MICROSCOPICALLY
 


* NUMBER OF ANIMALS NECROPSIED
 


D-4
 

TABLE Dl (CONTINUED) 

REPRODUCTIVE SYSTEM 

#PROSTATE
 

HYPERPLASIA, CYSTIC
 

*SEMINAL VESICLE
 

DEGENERATION, NOS
 

#TESTIS
 

DEGENERATION, NOS
 

NERVOOS SYSTEM
 


#BRAI N 

COPPORA AMYLACE A

 

SPECIAL SENSE ORGANS 

NON E 

MUSCULOSKELETA L SYSTEM 

NONE 

BODY CAVITIES 

*PLEURA 

FOAM-CELL 

*MESENTER Y 

STEATITIS 

PERIARTERITI S 

NECROSIS, FAT 

A LL OTHEF SYSTEMS 

*MULTIPLE ORGAN S 

CONTROL(UNTR ) 

22-2035

 (19)


 4 (21S)


 (19)


 (19)


 (18)

 9 (50% )

 (19 )

 (19)

 1 (5% ) 

(19 )

 LOW DOSE HIGU DOSE 

 22-2033 22-2031 

 (46)	 (44)
 


4 (9%) 3 (795)
 


 (49)	 (50)
 


1 (2X)
 


 (48)	 (48)
 


1 (2%)



 (47)

 (46) 

9 (19*) 11 (24%) 

 (49) (50) 

1 (2%)

 (49) (50) 

1 (2%) 

1 (2») 

 (49) (50) 

i_118JL	 f



#	 NUMBER OF ANIMALS WITH TISSUE EXAMINED MICROSCOPICALLY
 


*	 NUMBER OF ANIMALS NECROPSIED
 


D-5
 

TABLE Dl (CONCLUDED) 

CONTROL (UNTR ) LOH DOSE HIGH DOSE 

22-2035 22-2033 22-2031 

SPECIAL MORPHOLOG Y SUMMAR Y 

NO LESION REPORTED 2 8 17 

ANIMA L HISSING/NO NECROPSY 1 1

AUTO/NECROPSY/HISTO PEHF 1

# NUMBE R OF ANIMAL S WITH TISSUE EXAMINE D MICROSCOPICALLY 

* NUMBER OF ANIMAL S NECROPSIED 

D-6 
TABLE D2

 

SUMMARY OF THE INCIDENCE OF NONNEOPLASTIC LESIONS IN FEMALE MICE 

TREATED WITH 1-PHENYL-2-THIOUREA

 

HIGH DOSE 

22-2032 

50 

50 

50 

(49)
 


5 (10X)
 


1 (2*)
 


(46)

2 (4*) 

(42) 

(42) 

1 (2%) 

(47) 

1 (2X) 

(50) 

(<*8) 

ANIHALS 

ANIHALS 

ANIHALS 

ANIHALS 

INITIALLY IN STUDY 

HISSIHG 

NECROPSIED 

EXAHINE D HIS1 rOPATHOLOGICALLY** 

INTEGOHENTAR Y SYSTEH 

NONE 

RESPIRATOR Y SYSTEH 

#LUNG
 

INFLAHHATION, INTERSTITIAL
 


PNEUMONIA, CHRONIC HUPINE
 


PERIVASCULAR CUFFING
 


HEHATOPOJETIC SYSTEH 

*SPLEEN 

HYPEPPLASIA, LYHPHOID 

HEHATOPOIESIS 

#LYHPH NODE 

HEMOBRHAG E 

#HESEHTERIC L. NODE 

HYPERPLASIA , LYHPHOID 

CIRCULATORY SYSTEH 

IHYOCARDIU H 

INFLAHHATION , NOS 

*PULHONAR Y AflTERY 

HYPERTROPHY, NOS 

DIGESTIVE SYSTEH 

f LIVER 

# NUHBER 'OF ANIHAL S WITH TISSUE 

* NUHBEfi OF ANIHAL S NECROPSIED 

**EXCLUDES PARTIALLY AUTOLYZED ANIMALS 

(:ONTROL(UNTE ) 

22-2036 

20 

20 

20 

 (19)
 


(18) 

(16) 

1 (6X) 

(16) 

(19 ) 

(20) 

1 (5*) 

(19) 

LOW DOSE 

22-2034 

50 

8

42 

41 

(40)
 


1 (3X)
 


1 (3S)
 


(40) 

1 (3%) 

(36) 

(36) 

(40) 

(42) 

(39) 

 EXAHINBD HiCROSCOPICALLY 

D-7 
TABLE D2 (CONTINUED) 

HIGH DOSE 

22-2032 

5 (10X) 

1 (2«) 

2 (4%) 

2 (4%) 

1 (2%) 

(46) 

(48) 

1 (2%) 

(49) 

2 (4% ) 

(48) 

1 (231) 

2 (4%) 

3 (6%) 

1 (235) 

(47) 

1 (2«) 

(45) 

0*3) 

(50) 

1 12*L 

INFLAMMATION , ACUTE FOCAL 

INFLAMMATION , ACUTE/CHRONIC 

PERIVASCULA R CUFFING 

NECROSIS , FOCAL 

PIGMENTATION , NOS 

GLYCOGENIC CELL 

ANGIECTASI S 

#PANCPEA S 

CYSTIC DUCTS 

#STOMAC H 

INFLAMMATION , SUPPORATIV E 

tSMAL L INTESTIN E 

HYPERPLASIA , LYMPHOI D 

URINAR Y SYSTE M 

#KIDNE Y 

HYDRONEPHROSI S 

INFLAMMATION , NOS 

INFLAMMATION , CHRONIC 

PERIVASCULA R CUFFIN3 

NEPHHOSIS , CHOLEMIC 

#URINAR Y BLADDE R 

HYPERPLASIA , LYMPHOI D 

ENDOCRINE SYSTEM 

#ADRENA L CORTEX 

METAMORPHOSI S FATTY 

#THYROI D 

GOITER COLLOID 

REPRODUCTIV E SYSTEM 

#UTERU S 

HYDROMETR A 

CIST^ NOS 

CDNTROL(UNTR ) 

22-2036 

1 (555) 

1 (5%) 

(19) 

1 (5X) 

(18) 

(19) 

1 (535) 

(20) 

1 (5S) 

3 (15% ) 

1 (535) 

(19 ) 

(19) 

1 (5% ) 

(16 ) 

(20) 

1 15*L 

LOW DOSE 

22-2034 

7 (18X) 

3 (8X) 

1 (3£) 

(39) 

(39) 

(40) 

(40) 

1 (335) 

6 (15K ) 

3 (835) 

(41) 

(38) 

(32) 

1 (335) 

(41) 

1 (2%) 

2 S.5%1 

# NUMBE R OF ANIMAL S WITH TISSUE EXAMINE D MICROSCOPICALL Y 

* tKTMBFP OF ANIMAL S NECROPSIED 

D-8 
TABLE D2 (CONTINUED) 

CONTROL(ONTR ) LOW DOSE HIGH DOSE 

22-2036 22-2034 22-2032 

PYOMETRA 1 (5%) 2 (5«) 3 (6%) 

DECIDOA 1 (2*) 

* OTERO S/EHDOH ETRI OH (20) (1*1) (50) 

CYST. NOS 6 (3055) 11 (21%) 1 (2%) 

INFLAMMATION , NOS 1 (5%) 1 (2%) 3 (6%) 

INFLAMMATION , SOPPORATIVE 1 (2%) 

INFLAMMATION, ACOTE 2 (10% ) 1 (2») 1 (2*) 

HYPERPLASIA, NOS 1 (2% ) 1 (2%) 

HYPERPLASIA, CYSTIC 1 (5%) 17 (34%) 

* OTEROS/MYOHETRIOM (20) (41) (50) 

INFLAMMATION , NOS 1 (2%) 

tOVARY/OVIDOCT (20) (41) (50)

 

INFLAMMATION , NOS 1 (2*)

 

tOVARY (16) (33) (45) 

CYST, NOS 5 (31%) 4 (12*) 3 (7%) 

FOLLICOLAR CYST, NOS 1 (6%) 1 (2%) 

PAROVARIA N CYST 1 (6X ) 3 (9«) 

INFLAMMATION , NOS 1 (3%) 

PIGMENTATION, NOS 1 (2%) 

NERVOOS SYSTEM 

fBRAIN/MENINGES (20) (40) (49)
 


INFLAMMATION , NOS 1 (5%)
 


#BRAI N (20) (40) (49) 

CORPORA AMYLACEA 4 (20%) 11 (28%) 7 (14%) 

SPECIAL SENSE ORGANS
 


NONE
 


MOSCOLOSKELETAL SYSTEM
 


NONE
 


BODY CAVITIES
 


*PERITONEOM (20) (42) (50)
 


I NOBBER OF ANIMALS WITH TISSUE EXAMINED MICROSCOPICALLY
 


* NOMBER OF ANIMALS NECROPSIED
 


D-9
 

TABLE D2 (CONCLUDED) 

CONTROL(ONTR ) LOW DOSfi HIGH DOSE 

22-2036 22-2034 22-2032 

ALL OTHER SYSTEMS 

*MULTIPLE ORGANS (20) (42) (50) 

PERIVASCULAR CUFFIN3 3 (15%) U (10*) 9 (18S) 

SPECIAL MORPHOLOGY SUMMARY 

NO LESION REPORTED 6 2 

ANIMA L MISSING/NO NECROPSY 8 

AUTO/NECROPSY/NO HISTO 1 

* NUMBE R OF ANIMAL S WITH TISSUE EXAMINE D MICROSCOPICALLY 

* NUMBE R OF ANIMAL S NECROPSIE D 

D-10 
Review of the Bioassay of l-Phenyl-2-Thiourea* for Carcinogenicity
 


by the Data Evaluation/Risk Assessment Subgroup
 


of the Clearinghouse on Environmental Carcinogens
 


June 29, 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 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 responsi­
 bility of providing a peer review of reports prepared on
 


NCI-sponsored bioassays of chemicals studied for carcinogenic­
 ity. It is in this context that the below critique is given
 


on the bioassay of l-Phenyl-2-Thiourea for carcinogenicity.
 


The reviewer agreed with the conclusion in the report
 


that l-Phenyl-2-Thiourea was not carcinogenic under the
 


conditions of test. After a brief description of the
 


experimental design, he commented on the studies' defic­
 iencies. Among those noted were the inadequate control
 


group size, the lack of analytical data on the dietary
 


concentration of the test substance, the conduct of the
 


study in a room in which other chemicals were under test,
 
 and an improperly run subchronic study. Despite the short­
 comings, the reviewer said the study was still adequate
 


enough to form a conclusion on the carcinogenicity of
 


43
 

l-Phenyl-2-Thiourea. He moved that the report on the
 


bioassay of l-Phenyl-2-Thiourea be accepted as written. The
 


motion was approved without objection.
 


Clearinghouse Members present:
 


Arnold L. Brown (Chairman), Mayo Clinic
 


Paul Nettesheim, National Institute of Environmental
 


Health Sciences
 


Verne Ray, Pfizer Medical Research Laboratory
 


Verald K. Rowe, Dow Chemical U.S.A.
 
 Michael B. Shimkin, University of California at San Diego
 


Louise Strong, University of Texas Health Sciences Center
 


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.
 


tfU.S. GOVERNMEN T PRINTIN G OFFICE ! 1978-260-899/3190
 


NIH Publication No. 78-1704