1979 

National Cancer Institute 

CARCINOGENESIS 

Technical Report Series 

NO. 70 

BIOASSAY OF 

PARATHION 

FOR POSSIBLE CARCINOGENICITY 

CAS No. 56-38-2 

NCI-CG-TR-70 

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

Public Health Service 

National Institutes of Health 

BIOASSAY OF
 

PARATHION
 

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) 79-1320
 
11

 
BIOASSAY OF
 

PARATHION
 

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
 

parathion 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 environmental chemicals have the
 

capacity to produce cancer in animals. Negative results, in
 

which the test animals do not have a greater incidence of cancer
 

than control animals, do not necessarily mean that the test
 

chemical is not a carcinogen, inasmuch as 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 that exposure to
 

the chemical is a potential risk to man. The actual
 

determination of the risk to man from chemicals found to be
 

carcinogenic in animals requires a wider analysis.
 

CONTRIBUTORS; This bioassay of parathion was conducted by Gulf
 

South Research Institute, New Iberia, Louisiana, initially under
 

direct contract to NCI and currently under a subcontract to
 

Tracor Jitco, Inc., Rockville, Maryland, prime contractor for the
 

NCI Carcinogenesis Testing Program.
 

The experimental design was determined by Drs. J. H. Weisburger
 

(1,2) and R. R. Bates (1,3); the doses were selected by Drs. T.
 

E. Shellenberger (4,5), J. H. Weisburger, and R. R. Bates.
 

Administration of the chemical and observation of the animals
 

were supervised by Drs. T. E. Shellenberger and H. P. Burchfield
 

(4), with the technical assistance of Ms. D. H. Monceaux (4) and
 

Mr. D. Broussard (4). Histopathology was performed by Dr. T. E.
 

Murchison (6), and the diagnoses included in this report
 

represent his interpretation.
 

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

Mason Research Institute (7). Statistical analyses were
 

performed by Dr. J. R. Joiner (8) and Ms. P. L. Yong (8), using
 

methods selected for the bioassay program by Dr. J. J. Gart (9).
 

Chemicals used in this bioassay were analyzed under the direction
 

of Dr. H. P. Burchfield, and the analytical results were reviewed
 

by Dr. S. S. Olin (8).
 

This report was prepared at Tracor Jitco (8) under the direction
 

of NCI. Those responsible for the report at Tracor Jitco were 

Dr. L. A. Campbell, Director of the Bioassay Program; Dr. S. S. 

Olin, Deputy Director for Science; Drs. J. F. Robens and C. H. 

Williams, toxicologists; Dr. R. L. Schueler, pathologist; Dr. G.
 

L. Miller, Ms. Y. E. Presley, and Mr. W. D. Reichardt, technical
 

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

P. J. Graboske.
 

The following scientists at NCI (1) 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 (10),
 

Dr. Richard A. Griesemer, Dr. Morton H. Levitt, Dr. Harry A.
 

Milman, Dr. Thomas W. Orme, Dr. Robert A. Squire (11), Dr.
 

Sherman F. Stinson, Dr. Jerrold M. Ward, and Dr. Carrie E.
 

Whitmire.
 

(1) Carcinogenesis Testing Program, Divison of Cancer Cause and
 

Prevention, National Cancer Institute, National Institutes of
 

Health, Bethesda, Maryland.
 

(2) Now with the Naylor Dana Institute for Disease Prevention,
 

American Health Foundation, Hammond House Road, Valhalla,
 

New York.
 

(3) Now with the National Institute of Environmental Health
 

Sciences, P.O. Box 12233, Research Triangle Park, North
 

Carolina.
 

(4) Gulf South Research Institute, Atchafalaya Basin Laboratories,
 

P. 0. Box 1177, New Iberia, Louisiana.
 

(5) Now with the National Center for Toxicological Research,
 

Jefferson, Arkansas.
 

(6) Dawson Research Corporation, P.O. Box 8272, Orlando, Florida.
 

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

Rockville, Maryland.
 

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

Maryland.
 

(9) Mathematical Statistics and Applied Mathematics Section,
 

Biometry Branch, Field Studies and Statistics, Division of
 

Cancer Cause and Prevention, National Cancer Institute,
 

National Institutes of Health, Bethesda, Maryland.
 

(10)	 Now with Clement Associates, Inc., 1010 Wisconsin Avenue,
 

N.W., Suite 660, Washington, D. C.
 

(11)	 Now with the Division of Comparative Medicine, Johns Hopkins
 

University, School of Medicine, Traylor Building, Baltimore,
 

Maryland.
 

V 
vi

 
SUMMARY

 

A bioassay for possible carcinogenicity of technical-grade 

parathion was conducted by administering the test chemical in the 

diet to Osborne-Mendel rats and B6C3F1 mice. 

Groups of 50 rats of each sex were administered parathion at one 

of two doses for 80 weeks, then observed for 32 or 33 weeks. 

Time-weighted average doses for males were 32 or 63 ppm; for 

females, they were 23 or 45 ppm. All surviving rats were killed 

at 112 or 113 weeks. Groups of 50 mice of each sex were 

administered parathion at one of two doses, either 80 or 160 

ppm. The low-dose males were administered parathion for 71 

weeks; the high-dose males for 62 weeks; and the low- and 

high-dose females for 80 weeks. The animals were then maintained 

for observation and all surviving mice were killed at 89 or 90 

weeks. Matched controls consisted of groups of 10 untreated rats 

or mice of each sex; pooled controls of rats or mice taken from 

similar bioassays of other test chemicals were also used. 

Mean body weights of high-dose male and female rats and of highand low-dose male mice were generally lower than those of the 

matched -controls during the period of administration of the 

chemical. Mean body weights of the other groups of dosed rats 

and mice did not diffe r appreciably from those of the matched 

controls. Since body weights and survival of the female mice 

were not affected, female mice may have been able to tolerate a 

higher dose. Sufficient numbers of male and female animals of 

both species were at risk for the development of late-appearing 

tumors. 

In both male and female rats, the incidences of cortical adenomas 

or carcinomas of the adrenal showed dose-related trends (P less 

than 0.001) using pooled controls and, in direct comparisons, 

were higher in the high-dose groups (P less than 0.001) than in 

the pooled controls (males: pooled controls 3/80, matched 

controls 0/9, low-dose 7/49, high-dose 11/46; females: pooled 

controls 4/78, matched controls 1/10, low-dose 6/47, high-dose 

13/42). Most of the tumors were adenomas. When the matched 

controls were used, dose-related trends in incidences of the 

adrenal tumors were significant (males, P = 0.048; females, P = 

0.028); in direct comparisons, however, the incidences of the 

tumors in the individual groups did not differ significantly from 

those in corresponding matched controls. The incidences of the 

vii 
tumors in the dosed male and female rats were higher than those
 

in corresponding historical controls (males 8/148, females 5/180).
 

In mice, no tumors occurred in either sex at incidences that were
 

signficiantly higher in the dosed groups than in the
 

corresponding control groups.
 

It is concluded that under the conditions of this bioassay,
 parathion was not carcinogenic to B6C3F1 mice. In the male and
 

female Osborne-Mendel rats receiving parathion in their diet,
 

there was a higher incidence of cortical tumors of the adrenal
 

than in pooled or historical controls, suggesting that parathion
 

is carcinogenic to this strain of rat.
 

viii
 
TABLE OF CONTENTS
 

Page
 

I. Introduction 1
 

II. Materials and Methods... 3
 

A. Chemical 3
 

B. Dietary Preparation 4
 

C. Animals 5
 

D. Animal Maintenance 5
 

E. Subchronic Studies 7
 

F. Chronic Studies 9
 

G. Clinical and Pathologic Examinations 12
 

H. Data Recording and Statistical Analyses 14
 

III. Results - Rats 21
 

A. Body Weights and Clinical Signs (Rats) 21
 

B. Survival (Rats) 23
 

C. Pathology (Rats) 25
 

D. Statistical Analyses of Results (Rats) 26
 

IV. Results -Mice 31
 

A. Body Weights and Clinical Signs (Mice) 31
 

B. Survival (Mice) 33
 

C. Pathology (Mice) 35
 

D. Statistical Analyses of Results (Mice) 35
 

V. Discussion 37
 

VI. Bibliography 41
 

APPENDIXES
 

Appendix A Summary of the Incidence of Neoplasms in
 

Rats Fed Parathion in the Diet 43
 

Table Al Summary of the Incidence of Neoplasms in
 

Male Rats Fed Parathion in the Diet 45
 

Table A2 Summary of the Incidence of Neoplasms in
 

Female Rats Fed Parathion in the Diet 49
 

ix
 
Page 

Appendix B Summary of the Incidence of Neoplasms in 

Mice Fed Parathion in the Diet 53 

Table Bl Summary of the Incidence of Neoplasms in 

Male Mice Fed Parathion in the Diet 55 

Table B2 Summary of the Incidence of Neoplasms in 

Female Mice Fed Parathion in the Diet 58 

Appendix C Summary of the Incidence of Nonneoplastic 

Lesions in Rats Fed Parathion in the Diet 61 

Table Cl Summary of the Incidence of Nonneoplastic 

Lesions in Male Rats Fed Parathion 

in the Diet 63 

Table C2 Summary of the Incidence of Nonneoplastic 

Lesions in Female Rats Fed Parathion 

in the Diet 67 

Appendix D Summary of the Incidence of Nonneoplastic 

Lesions in the Mice Fed Parathion 

in the Diet 71 

Table Dl Summary of the Incidence of Nonneoplastic 

Lesions in the Male Mice Fed Parathion 

in the Diet 73 

Table D2 Summary of the Incidence of Nonneoplastic 

Lesions in Female Mice Fed Parathion 

in the Diet 75 

Appendix E Analyses of the Incidence of Primary Tumors 

in Rats Fed Parathion in the Diet 79 

Table El Analyses of the Incidence of Primary Tumors 

in Male Rats Fed Parathion in the Diet..... 81 

Table E2 Analyses of the Incidence of Primary Tumors 

in Female Rats Fed Parathion in the Diet 85 

Appendix F Analyses of the Incidence of Primary Tumors 

in Mice Fed Parathion in the Diet 91 

x
 
Table Fl Analyses of the Incidence of Primary Tumors 

in Male Mice Fed Parathion in the Diet 93 

Table F2 Analyses of the Incidence of Primary Tumors 

in Female Mice Fed Parathion in the Diet 96 

Appendix G Analysis of Formulated Diets for 

Concentrations of Parathion 99 

TABLES 

Table 1 Parathion Subchronic Feeding Studies in Rats 

and Mice 8 

Table 2 Parathion Chronic Feeding Studies in Rats 10 

Table 3 Parathion Chronic Feeding Studies in Mice 11 

FIGURES 

Figure 1 Growth Curves for Rats Fed Parathion 

in the Diet 22 

Figure 2 Survival Curves for Rats Fed Parathion 

in the Diet 24 

Figure 3 Growth Curves for Mice Fed Parathion 

in the Diet 32 

Figure 4 Survival Curves for Mice Fed Parathion 

in the Diet 34 

xi
 
xii

 
I. INTRODUCTION
 

Parathion
 

Parathion (CAS 56-38-2; NCI C00226) is an organophosphorus
 

pesticide that is relatively nonpersistent in the environment,
 

with high activity against insects and mites (Benke and Murphy,
 

1975; Hayes, 1975). It is highly toxic to mammals, because of
 

its rapid metabolic conversion in the liver to paraoxon, its
 

oxygen analog (Benke and Murphy, 1975; Hayes, 1975). Paraoxon is
 

the active form that accounts for toxicological and
 

pharmacological effects of parathion (Koelle, 1975).
 

Parathion is an inhibitor of cholinesterase, as shown by a marked
 

decrease in the concentration of enzyme in the erythrocytes of
 

Osborne-Mendel rats fed 5 or 25 ppm of the chemical in the diet
 

(Frawley et al., 1952). Parathion has a high acute oral toxicity
 

in Osborne-Mendel rats (LD^: 30 mg/kg in males, 3 mg/kg in
 

females).
 

1
 
T'arathion is used as an insecticide and acaricide on a wide
 

variety of fruit and nut trees, berries, vegetables, field crops,
 

and ornamental plants. Tolerances have been established for
 

residues of parathion on many food crops (EPA Compendium of
 

Registered Pesticides, 1973).
 

Parathion was selected for study in the Careinogenesis Testing
 

Program because of its extensive use on food and feed crops.
 

2
 
II. MATERIALS AND METHODS
 

A. Chemical
 

Parathion, which is the generic name for 0,0-diethy1-0-4­

nitrophenylphosphorothioate, was obtained as a technical-grade
 

material from the manufacturer, Monsanto Chemical Co., St. Louis,
 

Missouri. According to the manufacturer, the purity of the lot
 

used for the chronic studies (Lot No. AA114.2) was 99.5%. The
 

chemical was stored at 4 C in the original container until used.
 

The identity of the chemical was confirmed by analyses at Gulf
 

South Research Institute (infrared, ultraviolet, and nuclear
 

magnetic resonance spectra; isobutane chemical ionization mass
 

spectrum). Gas-liquid chromatography showed a single homogeneous 

peak, consistent with the manufacturer's assay. Elemental 

analysis was consistent with C,QH..NO-PS, the molecular 

formula for parathion. 

The term parathion is used in the remainder of the report to
 

designate the technical-grade material.
 

3
 
B. Dietary Preparation
 

All diets containing parathion were formulated once per week
 

using Wayne® Lab Blox animal meal (Allied Mills, Inc., Chicago,
 

111.) to which was added the required amount of parathion for
 

each dietary concentration. The test chemical was first
 

dissolved in a small amount of acetone (Mallinckrodt, Inc., St.
 

Louis, Mo.), which was then added to the feed. Corn oil
 

(LouAna®, Opelousas Refinery Co., Opelousas, La.) was also
 

added to the feed at 2% of the final feed weight, primarily as a
 

dust suppressant, and the diets were mixed mechanically in a
 

Hobart blender to assure homogeneity of the mixtures and
 

evaporation of the acetone. Diets for the control groups of
 

animals also contained corn oil equal to 2% of the final weight
 

of feed. The diets were stored at room temperature until used,
 

but no longer than 1 week before use.
 

The stability of parathion in feed was tested by determining the
 

concentration of the chemical in formulated diets at intervals
 

over a 7-day period. Diets containing 80 or 160 ppm parathion
 

showed no significant change in concentration on standing at
 

ambient temperature for this period.
 

As a quality control test on the accuracy of preparation of the
 
diets, the concentration of parathion was determined in different
 

batches of formulated diets during the chronic studies. The
 

results are summarized in Appendix G. At each dietary
 

concentration, the mean of the analytical concentrations for the
 

checked samples was within 2.0% of the theoretical concentration,
 

and the coefficient of variation was never more than 6.5%.
 

C. Animals
 

Rats and mice of each sex, obtained through contracts of the
 

Division of Cancer Treatment, National Cancer Institute, were
 

used in these bioassays. The rats were of the Osborne-Mendel
 

strain obtained from Battelle Memorial Institute, Columbus, Ohio,
 

and the mice were B6C3F1 hybrids obtained from Charles River
 

Breeding Laboratories, Inc., Wilmington, Massachusetts. On
 

arrival at the laboratory, all animals were quarantined (rats for
 

10 days, mice for 12 days), then assigned to control or dosed
 

groups.
 

D. Animal Maintenance
 

All animals were housed in rooms in which the temperature ranged
 

5
 
from 22 to 24°C, and the relative humidity from 40 to 70%. The
 

air in each room was changed 10 to 12 times per hour. Fluorescent
 

light provided illumination 10 hours per day. Food and water
 

were provided ad libitum.
 

The rats were housed individually in hanging galvanized steel
 

mesh cages, and the mice were housed in plastic cages with filter
 

bonnets, five animals per cage for females, or two or three
 

animals per cage for males. Initially, rats were transferred
 

every week to clean cages; later in the study, cages were changed
 

every 2 weeks. Absorbent sheets under the rat cages were changed
 

three times per week. Mouse cages were provided with
 

Absorb-dri bedding (Lab Products, Inc., Garfield, N. J.), and
 

the mice were transferred to clean cages every week. Feeder jars
 

and water bottles were changed and sterilized three times per
 

week.
 

Cages of control and dosed mice were placed on separate racks in
 

the same room. Animal racks for both species were rotated
 

laterally every week; at the same time, each cage was changed to
 

a different position within the same column. Rats were housed in
 

a room by themselves. Mice were maintained in the same room as
 

mice in the following feed studies:
 
(CAS 60-51-5) dimethoate
 

(CAS 13171-21-6) phosphamidon
 

E. Subchronic Studies
 

Subchronic feeding studies were conducted to estimate the maximum
 

tolerated doses of parathion, on the basis of which two
 

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

doses) were determined for administration in the chronic
 

studies. Groups of five rats and five mice of each sex were
 

administered feed containing parathion at one of several doses,
 

and groups of five animals of each sex and species were
 

administered basal diet only. The dosed groups were fed the test
 

diets for 6 weeks, followed by 2 weeks of observation.
 

Table 1 shows the doses used and the mean body weights of dosed
 

animals at week 6 expressed as percentages of the mean weights of
 

controls; it also shows the number of animals that died in each
 

dosed group during the course of administration and the week on
 

study when the last death occurred.
 

On the basis of these results, the initial low and high doses for
 

the chronic studies were set at 40 and 80 ppm for male rats and
 

7 
Table 1. Parathion Subchronic Feeding Studies in Rats and Mice
 

Male 

Mean Weight 

Mortality at Week 6 

Dose Number Week on as % of 

(ppm) Dead Study Control 

RATS 

5 101
 

10 96
 

20 97
 

40 97
 

80 92
 

160 2 2 80
 

320 5 2
 

MICE
 

First Study
 

5 102
 

10 103
 

20 99
 

40 106
 

80 94
 

160 88
 

Second Study
 

160 86
 

320 5 2
 

640 5 2
 

1,280 5 1
 

Female
 

Mean Weight
 

Mortality at Week 6
 

Number Week on as % of
 

Dead Study Control
 

101
 

96
 

94
 

99
 

2 1 76
 

5 2
 

5 1
 

121
 

113
 

116
 

106
 

104
 

111
 

100
 

4 3
 85
 

5 2
 

5 1
 

8 
20 and 40 ppm for female rats; the low and high doses were set at
 

80 and 160 ppm for male and female mice.
 

F. Chronic Studies
 

The test groups, doses administered, and durations of the chronic
 

feeding studies are shown in tables 2 and 3.
 

Since the numbers of animals in the matched-control groups were
 

small, pooled-control groups also were used for statistical
 

comparisons. In rats, the matched controls from the current
 

bioassay of parathion were combined with matched controls from
 

bioassays of azinphosmethyl (CAS 86-50-0), captan (CAS 133-06-2),
 

chloramben (CAS 133-90-4), chlordane (CAS 57-74-9), dimethoate,
 

heptachlor (CAS 76-44-8), malathion (CAS 121-75-5), and picloram
 

(CAS 1918-02-1). The pooled-control groups for statistical tests
 

using rats consisted of 90 males and 90 females.
 

In mice, the matched controls from the current bioassay of
 

parathion were combined with matched controls from bioassays of
 

azinphosmethyl, chlordane, dieldrin (CAS 60-57-1), dimethoate,
 

heptachlor, lindane (CAS 58-89-9), malathion, phosphamidon,
 

photodieldrin (CAS 13366-73-9), and tetrachlorvinphos (CAS
 

9 
Table 2. Parathion Chronic Feeding Studies in Rats
 

Sex and Initial Parathion Time on Study Time-Weighted 

Test No. of in Diet(b) Dosed Observed(c) Average Dose(b) 

Group Animals (a) (ppm) (weeks) (weeks) (ppm) 

Male 

Matched-Control 10 0 112 

Low-Dose 50 40 13 32 

30 67 

0 32 

High-Dose 50 80 13 63 

60 67 

0 32 

Female
 

Matched-Control 10 0 112
 

Low-Dose 50	 20 13 23
 

30 21
 

20 46
 

0	 32
 

High-Dose 50	 40 13 45
 

60 21
 

40 46
 

0	 32-33
 

(a) Animals were 5 weeks of age	 when placed on study.
 

(b) After 13 weeks, doses for males and females were made uniform
 

for both sexes of rats. After 33 weeks, doses for females were
 

lowered, due to generalized tremors among the high-dose females.
 

(c) When diets containing parathion were discontinued, dosed rats
 

and their matched controls were fed control diets without corn
 

oil for 1 week, then control diets (2% corn oil added) for an
 

additional 31 or 32 weeks.
 

(d) Time-weighted average dose = £(dose in ppm x no. of weeks at that dose)
 

E(no. of weeks receiving each dose)
 

10
 
Table 3. Parathion Chronic Feeding Studies in Mice
 

Sex and Initial Para th ion Time on Study 

Test No. of in Diet Dosed Observed(b) 

Group Animals (a) (ppm) (weeks) (weeks) 

Male 

Matched-Control 10 0 90
 

Low-Dose 50 80 71
 

0 18
 

High -Dose 50 160 62
 

0 28
 

Female
 

Matched-Control 10 0 90
 

Low-Dose 50 80 80
 

0 9
 

High -Dose 50 160 80
 

0 10
 

(a) Animals were 5 weeks of age when placed on study.
 

(b) When diets containing parathion were discontinued, high-dose
 

males received control diets without corn oil for 8 weeks,
 

then control diets (2% corn oil added) for an additional 20
 

weeks. Low-dose males and all females received control diets
 

until termination of the study.
 

11
 
961-11-5). The poo led-control groups for statistical tests using 

mice consisted of 140 males and 130 females. 

The bioassays of the test chemicals other than parathion were 

also conducted at Gulf South Research Institute, and the pooled 

controls used for statistical evaluation were started no more 

than 3 months apart from the matched controls of parathion. The 

matched-control groups of rats and mice for the different test 

chemicals that were used in the pool were of the same strain and 

obtained from the same supplier; they were diagnosed by different 

pathologists but the diagnoses were reviewed by NCI pathologists. 

G. Clinical and Pathologic Examinations
 

All animals were observed twice per day. Animals were weighed at
 

approximately every 2 weeks for the first 3 months, then monthly
 

thereafter, and palpated for masses at each weighing. Moribund
 

animals and animals that survived to the end of the bioassay were
 

killed using ether and necropsied. Necropsies were also
 

performed on all animals found dead, unless precluded by
 

auto lysis or severe cannibalization.
 

12
 
The pathologic evaluation consisted of gross and microscopic
 

examination of major tissues, major organs, and all gross
 

lesions. The tissues were preserved in 10% buffered formalin,
 

embedded in paraffin, sectioned, and stained with hematoxylin and
 

eosin. The following tissues were examined microscopically:
 

skin, lungs and bronchi, trachea, bone and bone marrow, spleen,
 

lymph nodes, heart, salivary gland, liver, gallbladder (mice),
 

pancreas, stomach, small intestine, large intestine, kidney,
 

urinary bladder, pituitary, adrenal, thyroid, parathyroid,
 

mammary gland, prostate or uterus, testis or ovary, and brain.
 

Occasionally, additional tissues were also examined
 

microscopically. 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 may have died early, been missing, or
 

been in advanced states of cannibalization or autolysis. 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.
 

13
 
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 appropriate 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
 

sec tions.
 

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
 

14
 
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., lytnphomas), 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
 

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

15
 
dose level. When results for a number of dosed 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
 

16
 
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 less than 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
 

17
 
binomial probability of the incidence of a specific type of tumor
 

in a dosed group of animals and p 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 dosed 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
 

dosed 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 dosed 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 less than 0.025 one-tailed test when the
 

control incidence is not zero, P less than 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
 

lowerlimit indicates the absence of a significant result while
 

the upper limit indicates that there is a theoretical possibility
 

18
 
of the induction of tumors by the test chemical, which could not
 

be detected under the conditions of this test.
 

19
 
20

 
III. RESULTS - RATS
 

A. Body Weights and Clinical Signs (Rats)
 

Mean body weights of high-dose male and high-dose female rats 

were generally lower than those of the matched controls during 

the period of administration of the chemical, particularly for 

females during weeks 14 through 35, at which time the dose was 

increased. After administration was discontinued, the mean body 

weights of dosed and control animals were more nearly comparable 

(figure 1). Fluctuation in the growth curve may be due to 

mortality; as the size of a group diminishes, the mean body 

weight may be subject to variation. 

During the first 6 months of the bioassay, the dosed animals were 

generally comparable to the controls in appearance and behavior. 

One high-dose male and two high-dose females had body tremors 

during this period. During the second 6 months, 1/50 high-dose 

males, 1/50 low-dose females, and 25/50 high-dose females had 

generalized body tremors. During this same period, 1/50 highdose males, 1/50 low-dose females, and 5/50 high-dose females had 

diarrhea. At week 32, a few animals in both control and dosed 

groups developed exophthalmos and corneal opacity, accompanied in 

21 
TIME ON STUDY (WEEKS) 

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

22 
some cases by thickening of the palpebral conjunctival
 

membranes. This was diagnosed as viral conjunctivitis by the
 

pathologists at the laboratory.
 

During the first half of the second year, clinical signs among
 

the dosed animals were noted at a low or moderate incidence, and
 

during the second half of the year they increased. These signs
 

were characteristic of aging, but also included hyperactivity and
 

hyperexcitability generally associated with organophosphorus
 

pesticide exposure.
 

B. Survival (Rats)
 

The Kaplan and Meier curves estimating the probabilities of
 

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

the doses of this bioassay, together with those of the matched
 

controls, are shown in figure 2. The results of the Tarone test
 

for positive dose-related trend in mortality over the bioassay
 

are not significant in either sex.
 

In male rats, 36/50 (72%) of the high-dose group, 31/50 (62%) of
 

the low-dose group, and 7/10 (70%) of the matched controls lived
 

to the end of the study. In female rats, 34/50 (68%) of the
 

23
 
TIME ON STUDY (WEEKS) 

Figure 2. Survival Curves For Rats Fed Parathion In The Diet 

24 
high-dose group, 36/50 (72%) of the low-dose group, and 7/10
 

(70%) of the matched controls lived to the end of the study.
 

Sufficient numbers of animals in dosed and control groups were at
 

risk for the development of late-appearing tumors.
 

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.
 

The variety of neoplasms represented among both dosed and control
 

rats was not unusual, with the exception of a pituitary tumor in
 

one low-dose male rat. This was a solitary tumor that consisted
 

of an area of solid adenoma, as commonly encountered in
 

laboratory rats, and a second component that was made up of
 

small, rounded glandular spaces lined by a single layer of
 

mucin-secreting cells somewhat suggestive of goblet cells.
 

Whether these areas represented two independent tumors of the
 

pituitary or a mixed tumor or adenoma of the pituitary is
 

uncertain. Each of the other types of tumors represented has
 

been encountered previously as a spontaneous lesion in the
 

Osborne-Mende1 rat.
 

25
 
The incidence of adrenal cortical adenomas and carcinomas was
 

increased in high-dose male (11/46) and female (13/42) rats, as
 

compared with matched controls (male 1/9, female 0/10). However,
 

since the number of matched-control rats was small, this finding
 

could not necessarily be attributed to administration of the
 

chemical.
 

A variety of nonneoplastic lesions were represented among both
 

control and dosed animals. Such lesions have been encountered
 

previously as spontaneous occurrences in laboratory rats and are
 

considered as such in these animals.
 

Based on the pathologic examination, parathion did not appear to
 

be carcinogenic in Osborne-Mendel 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 of one group and at an incidence of at least 5%
 

in one or more than one group.
 

26
 
In male rats, the result of the Cochran-Armitage test on the
 

incidence of animals with cortical adenomas or carcinomas of the
 

adrenal is significant (P less than 0.001) when the
 

pooled-control group is used, and the results of the Fisher exact
 

test show that the incidence in the high-dose group is
 

significantly higher (P less than 0,001) than that in the
 

pooled-control group. The Fisher exact comparison of incidences
 

in the low-dose and pooled-control groups indicates a probability
 

level of 0.035, which is above the 0.025 level required by the
 

Bonferroni inequality criterion when multiple comparison is
 

considered. The adenomas were the principal lesions contributing
 

to the significance of the combined neoplasms. When the
 

incidences of cortical adenomas alone are tested, the results of
 

the statistical tests are P » 0.001 in the Cochran-Armitage test
 

using the pooled-control group and P «• 0.002 in the Fisher exact
 

test between the high-dose group and the pooled controls. In
 

females, the Cochran-Armitage probability levels for the
 

incidence of adrenal cortical adenomas or carcinomas are P less
 

than 0.001 and P = 0.028, respectively, when the pooled and
 

matched controls are used. The results of the Fisher exact test
 

show that the incidence in the high-dose female rats is
 

significantly higher (P less than 0.001) than that in the pooled
 

controls. Historical records of the Carcinogenesis Testing
 

Program at this laboratory indicate that in the male rats,
 

27
 
cortical adenomas, cortical carcinomas, or adenomas, NOS, were
 

observed in 8/178 (4.5%) of the controls. In female rats there
 

were 5/180 (2.7%) cortical adenomas or adenomas, NOS, of the
 

adrenal.
 

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

dose-related trend in the incidence of islet-cell carcinomas of
 

the pancreas shows a significant dose-related trend (P = 0.024)
 

when the pooled-control group is used, but the results of the
 

Fisher exact test for comparison of the incidences of tumors in
 

the high-dose and pooled-control groups indicate a probability
 

level of 0.048, which is above the 0.025 level required by the
 

Bonferroni inequality criterion when multiple comparison is
 

considered. The results of the tests using the matched controls
 

are not significant.
 

In female rats, the Cochran-Armitage test for dose-related trend
 

in the incidence of fibroadenomas of the mammary gland is not
 

significant, but an indicated departure from linear trend is
 

observed (P = 0.004) when the pooled-control group is used, since
 

the incidence in the low-dose group is higher than that in the
 

high-dose group. The results of the Fisher exact test show that
 

the incidence in the low-dose group is significantly higher than
 

that in the pooled controls (P » 0.002); however, this positive
 

28
 
result is not confirmed by the incidence in the high-dose group.
 

The matched controls have an incidence of 2/10 (20%) compared
 

with 8/50 (16%) in the high-dose group, and the results of the
 

tests using the matched controls are not significant.
 

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

dose-related trend in the incidence of follicular-cell adenoma of
 

the thyroid is significant (P = 0.037) when the pooled-control
 

group is used. The Fisher exact comparison of incidences in the
 

high-dose and pooled-control groups indicates a P value of 0.046,
 

which is above the 0.025 level required for significance when the
 

Bonferroni inequality criterion is used for multiple comparison.
 

The Fisher exact comparison between the low-dose and the
 

matched-control groups indicates a P value of 0.035 in the
 

negative direction.
 

In summary, the incidence of the adrenal tumors in male and
 

female rats may be associated with the administration of
 

parathion.
 

29
 
30

 
IV. RESULTS -MIC E
 

A. Body Weights and Clinical Signs (Mice)
 

Mean body weights of the dosed male mice were lower than those of
 

the controls during the period of administration of the chemical,
 

but were comparable when administration was discontinued (figure
 

3). Fluctuation in the growth curve may be due to mortality; as
 

the size of a group diminishes, the mean body weight may be
 

subject to variation. Mean body weights of dosed females were
 

unaffected by the parathion when compared with controls.
 

During the first year of the bioassay, the dosed animals were
 

generally comparable to the controls in appearance and behavior.
 

Wounds from fighting were noted on the mice during the second
 

half of the first year and continuing until termination of the
 

bioassay.
 

Clinical signs in both male and female animals of the dosed
 

groups noted with increasing frequency during the second year of
 

the bioassay included tremors and alopecia; abdominal distention
 

was noted in all dosed males, and most dosed females. Rough hair
 

coats were observed beginning at week 52 in the low-dose male
 

31
 
TIME ON STUDY (WEEKS) 

Figure 3. Growth Curves For Mice Fed Parathion In The Diet 

32 
group and at week 75 in the high-dose male group. All low-dose
 

males had diarrhea by week 64 and all high-dose males were
 

showing signs of hyperexcitability by week 60.
 

B. Survival (Mice)
 

The Kaplan and Meier curves estimating the probabilities of
 

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

the doses of this bioassay, together with those of the matched
 

controls, are shown in figure 4. In male mice, the result of the
 

Tarone test shows a positive dose-related trend in mortality (P =
 

0.029) over the bioassay. In female mice, the result of the
 

Tarone test does not show any significant dose-related trend in
 

mortality; in fact, the controls showed a lower survival than the
 

dosed groups.
 

There were 40/50 (80%) of the high-dose males, 46/50 (92%) of the
 

low-dose males, and all 10 of the matched controls still alive at
 

week 89. Forty-six out of 50 (92%) of the high-dose females,
 

46/50 (92%) of the low-dose females, and 8/10 (80%) of the
 

matched controls were still alive at week 89. Sufficient numbers
 

of animals in dosed and control groups were at risk for the
 

development of late-appearing tumors.
 

33
 
TIME ON STUDY (WEEKS)

 

Figure 4. Survival Curves For Mice Fed Parathion In The Diet 

34 
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.
 

A variety of neoplastic and nonneoplastic lesions are represented
 

among both control and dosed animals. Both neoplastic and
 

nonneoplastic lesions are judged to be distributed without any
 

relationship to administration of the chemical.
 

Based on the pathologic examination, parathion was not
 

carcinogenic in B6C3F1 mice under the conditions of this bioassay.
 

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 of one group and at an incidence of at least 5%
 

in one or more than one group. In mice, the incidences of tumors
 

at any site cannot be related in a positive direction to
 

administration of the chemical. Significant results in the
 

35
 
negative trend are observed in the incidence of hepatocellular
 

carcinoma in male mice when the pooled-control group is used.
 

In each of the 95% confidence intervals for 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 that for
 

the incidence of hepatocellular carcinoma in the high-dose and
 

pooled-control groups of male mice) has an upper limit greater
 

than one, indicating the theoretical possibility of the induction
 

of tumors by parathion, which could not be detected under the
 

conditions of this test.
 

36
 
V. DISCUSSION
 

Parathion was toxic to both rats and mice at the doses administered in this bioassay, as shown by decreased mean body weights 

of the dosed male and female rats and male mice, and by the 

presence of such clinical signs as tremors, hyperactivity, and 

hyperexcitability associated with intoxication by parathion and 

other cholinesterase inhibitors (Radeleff, 1970). Since mean 

body weights and survival of the female mice were not affected, 

female mice may have been able to tolerate a higher dose. 

Sufficient numbers of male and female animals of both species 

were at risk for the possible development of late-appearing 

tumors. 

In both male and female rats, the incidences of cortical adenomas 

or carcinomas of the adrenal showed dose-related trends (P less 

than 0.001) using pooled controls and, in direct comparisons, 

were higher in the high-dose groups (P less than 0.001) than in 

the pooled controls (males: pooled controls 3/80, matched 

controls 0/9, low-dose 4/49, high-dose 11/46; females: pooled 

controls 3/80, matched controls 0/9, low-dose 6/47, high-dose 

13/42). The principle contribution to the significance of these 

tumors is made by the incidence of adenomas. When the matched 

37 
controls were used, dose-related trends in incidences of the
 

tumors were significant (males, P = 0.048; females, P - 0.028);
 

in direct comparisons, however, the incidences of the tumors in
 

the individual dosed groups did not differ significantly from
 

those in corresponding matched controls. The incidences of the
 

tumors in the dosed male and female rats were higher than those
 

in corresponding historical controls (males 8/148, females 5/180).
 

Because of the statistical significance of the comparison of the
 

incidence of adrenal tumors in dosed animals with that of pooled
 

controls and the relatively low incidences observed among
 

historical controls (even taking into account group variation),
 

it is considered that the incidence of adrenal tumors in male and
 

female rats may be associated with the administration of
 

parath ion.
 

In mice, no tumors occurred in either sex at incidences that were
 

significantly higher in the dosed groups than in the
 

corresponding control groups.
 

Chronic toxicity of parathion has previously been investigated in
 

rats by Hazleton and Holland (1950), by Barnes and Denz (1951),
 

and by the Food and Drug Administration (Lehman, 1965). In the
 

Hazleton and Holland study, male albino rats were administered 0,
 

38
 
10, 25, 50, or 100 ppm of parathion in the diet for 2 years, and
 

females albino rats were given 0, 10, or 50 ppm for 64 weeks or
 

100 ppm for an unstated period. At 100 ppm, peripheral tremors
 

and irritability were noted in the males, but only for the first
 

several weeks; females were more susceptible than the males at
 

this dose. No neoplasms were reported in the tissues examined,
 

which included the liver and adrenal gland. Barnes and Denz
 

(1951) fed parathion in the diet for periods of up to 1 year to
 

male and female albino rats at 10, 20, 50, 75, or 100 ppm.
 

Typical cholinergic signs were observed in the groups receiving
 

50, 75, or 100 ppm. Survival was low at 50 ppm and above, but
 

was high at 10 and 20 ppm, with no toxic signs observed. Lesions
 

of the submaxillary gland and the pancreas and hypoplasia of the
 

spleen and thymus, associated with acute poisoning in other
 

studies by these authors, were found in animals dosed with 50 or
 

75 ppm but not in those dosed with 10 or 20 ppm. No neoplasms
 

were reported. In the work carried out at the FDA (Lehman,
 

1965), male and female rats were fed parathion in the diet for 2
 

years at concentrations of 2, 5, 10, 25, 50, or 100 ppm. There
 

was no significant effect on mortality, no histologic changes
 

attributable to the administration of parathion were noted, and
 

the incidence of tumors was not increased in the dosed animals.
 

It is concluded that under the conditions of this bioassay,
 

39
 
parathion was not carcinogenic to B6C3F1 mice. In the male and
 

female Osborne-Mendel rats receiving parathion in their diet,
 

there was a higher incidence of cortical tumors of the adrenal
 

than in pooled or historical controls, suggesting that parathion
 

is carcinogenic to this strain of rat.
 

40
 
VI. BIBLIOGRAPHY
 

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

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

Barnes, J. M. and Denz, F. A., The chronic toxicity of 

p-nitrophenyl diethyl thiophosphate (E. 605). J^ Hygiene 

4^:430-441, 1951. 

Benke, G. M. and Murphy, S. D., The influence of age on the
 

toxicity and metabolism of methyl parathion and parathion in male
 

and female rats. Toxicol. Appl. Pharmacol. 3^:254-269, 1975.
 

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

Panel on Carcinogenicity £f_ the Cancer Research Commission £f
 

the UICC, Vol. :2. International Union Against Cancer, Geneva,
 

1969.
 

Cox, D. R., Regression models and life tables. J_^ R_^ Statist.
 

Soc. B 34 (2);187-220, 1972.
 

Cox, D. R. Analysis o_f Binary Data, Methuen and Co., Ltd.,
 

London, 1970, pp. 48-52.
 

Environmental Protection Agency, EPA Compendium of Registered
 

Pesticides, U.S. Government Printing Office, Washington, D.C.,
 

1973, III-P-2.1-2.164.
 

Frawley, J. P., Hagan, E. C. , and Fitzhugh, 0. G., A comparative
 

pharmacological and toxicological study of organic phosphate ­

anticholinesterase compounds. In: The Journal ojf Pharmacology
 

and Experimental Therapeutics, Vol. 152, van Dyke, H. B., ed.,
 

American Society for Pharmacology and Experimental Therapeutics
 

Incorporated, Baltimore, Md., 1952, pp. 156-165.
 

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

significance tests, confidence limits and adjustments for
 

stratificaton. Rev. Int. Statist. Inst. 39 (2);148-169, 1971.
 

Hayes, W. J., Jr., Factors influencing toxicity. In: Toxicology
 

c)f_ Pesticides, Williams and Wilkins Co., Baltimore, Md., 1975,
 

pp. 69 and 88.
 

41
 
Hazleton, L. W. and Holland, E. G., Pharmacology and toxicology
 

of parathion. In: Agricultural Control Chemicals, American
 

Chemical Society, Washington, D. C., 1950, pp. 31-38.
 

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

incomplete observations. J^ Amer. Statist. Assoc. 53;457-481,
 

1958. ~~ ~~
 

Koelle, G. B., Anticholinesterase agents. In: The
 

Pharmacological Basis £f Therapeutics, 5th edition, Goodman, L.
 

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

1975, pp. 445-466.
 

Lehman, A. J., Cholinesterase inhibitors. In: Summaries c)f
 

Pesticide Toxicity, Food and Drug Administration, Department of
 

Health, Education, and Welfare, Washington, D. C., 1965, pp.
 

58-60.
 

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.
 

Radeleff, R. D., Parathion. In: Veterinary Toxicology, 2nd
 

edition, Lea and Febiger, Philadelphia, Pa., 1970, pp. 228-229.
 

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

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

induced by different numbers of administrations of benzo (a)
 

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

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

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

42
 
APPENDIX A
 

SUMMARY OF THE INCIDENCE OF NEOPLASMS IN
 

RATS FED PARATHION IN THE DIET
 

43
 
44

 
TABLE A1. 

SUMMARY OF THE INCIDENCE OF NEOPLASMS

FED PARATHION IN THE DIET 

AMKAIS INITIALLY IN STUDY
 

ANIMAL S NEC5CPSIED
 

ANIMAL S EXAMINED HISTOFATHOLOGIC ALL Y
 

INTEGUMENTAR Y SYS15M
 

*SKIN
 

KEBATCACANTHOMA
 

FIERCMA
 

FIEROSARCOMA
 

*SUECUT TISSUE
 

SARCOMA, NOS
 

FIBEOSARCOMA
 

BESPIEATORY SYSTEM
 

rflUNG
 

ALVEOLAR/BRONCHIOLAR ADENOMA
 

ALVEOLAH/3RONCHIOLAR CARCINOMA
 

CCB7ICAL CARCINOMA. METASTATIC
 

HEKATOFOIETIC SYSTEM
 

*BULTIPLE ORGANS
 

MALIG.LYMPHOHA, UNCIFFER-TYPE
 

#SFLEEN
 

FIBROSABCOMA
 

HAHARTOMA
 

*LYt!PH NODE
 

HEHANGIOSABCOflA
 

tKESENTERIC L. NODE
 

HEHANGIOSARCGMA
 

tFEBCRAL LYMPH NODE
 

SAR£CBAi_NSSJt_(!llAS2&H£_
 

CONTROL
 

1C
 

10
 

10
 

(10)
 

(10)
 

(10)
 

(10)
 

(10)
 

(9)
 

(9)
 

(9)
 

 IN MALE RATS 

LOW DOSE HIGH DOSE
 

50	 50
 

50	 49
 

50	 49
 

(50) (49)
 

1 (2%)
 

1 (2%)
 

1 (2%) 1 (2%)
 

(50) (<*9)
 

1 (2%)
 

2 (UX) 1 (2%)
 

(50)	 (48)
 

1 (2%)
 

1 (2%)
 

1 (2%)
 

(50)	 (49)
 

1 (2%)
 

(50)	 <<»7)
 

2 («X)
 

1 (2X)
 

(39) (34)
 

•1 OX)
 

(39)	 (34)
 

1 (3X)
 

(39)	 (34)
 

1__I141_
 

# NUMEE R OF ANIMAL S WITH TISSUE EXAMINE D MICROSCOPICALLY 

* NUflEE R OF ANIMAL S NECROPSIED 

45 
TABLE A1. MALE RATS: NEOPLASMS (CONTINUED) 

CONTROL LOW DOSE
 

CIRCULATORY SYSTEM
 

•HEASI	 (10) (50)
 

FIBRCSARCOKA. MF1ASTATIC
 

DIGESTIVE SYSTEM
 

(tSALIVAEY GLAND (9) (U8)
 

KEMANGIOSARCCMA
 

OLIVER (10) (50)
 

NECFLASTIC NODULE
 

HEPATOCELLULAR CARCINOMA
 

UKINAE Y SYSTEM
 

NCNE
 

ENDOCRINE SYSTEM
 

#EnUITARY 

ADENOMA, NOS 

MIXED TUMOK, EENIGN 

(9)

U (4tX)

 (U2) 

 10 (2«%) 

1 (2*) 

#ADRENAL 

CORTICAL ADSNOHA 

CORTICAL CARCINOMA 

FHECCHBOMOCYTOMA 

(9) (U9) 

5 (10X) 

2 (««) 

tTHYBCIC (10) («6)
 

FOLLICULAB-CELL ADENOMA 3 (30X) 2 (4X)
 

C-CELL CABCINCMA 1 (2X)
 

#EARATHYBOIC (5) (3«)
 

ADENOMA, NOS 1 (20X)
 

#EANCREATIC ISLETS (9) (U9)
 

ISLET-CELL CARCINOMA 1 (2X)
 

REPECCUCTIVE SYSTEM
 

*MAKMARY GLAND (10) (50)
 

_IJ6£OBA_M, , ^^ „ ^^2,1HIL
 

* NUMEER OF ANIMALS WITH TISSDE EXAMINED MICEOSCOPICALLY
 

* NOMEEB OF ANIMALS NECROPSIED
 

HIGH DOSE
 

(U8)
 

1 (2%)
 

(«4)
 

1 (2X)
 

(«9)
 

3 (6X)
 

1 <2X)
 

C»3)
 

13 (30X)
 

(46)
 

9 (20X)
 

2 (<>X)
 

2 («)
 

(«3)
 

8 (19X)
 

1 (2X)
 

(29)
 

(«6)
 

3 (7X)
 

C»9)
 <••••••_«- TIT -irr -r-f
 

46 
TABLE A1. MALE RATS: NEOPLASMS (CONTINUED) 

CONTROL LOW DOSE HIGH DOSE 

NESVCU S SYSTEM 

NONE 

SPECIAL SENSE ORGANS 

NCNE 

HUSCULCSRELEIAL SYSTEM 

*SKELETAL MUSCLE

SA8CCMA, NOS

 (10) (50) (U9) 

1 (2%) 

BODY CAVITIES 

NCNE 

ALL CTHER SYSTEMS 

NONE 

ANIMA L DISPOSITION SUMMABY 

ANIMALS INITIALLY IN STUDY

NATURAL DEATHS

MORIBUND SACRIFICE

SCHEDULED SACRIFICE 

ACCIDENTALLY KILLED 

TERMINAL SACRIFICE

ANIMAL MISSING 

 10

 3

 7

 50

 9

 10

 31

 50 

6 

8 

36 

a. INCUDES. AOTCJ.UEP ANIHAIS ,

* NUHEEB OF ANIMALS WITH TISSUE EXAMINED HICEOSCOPICALLY 

* NUMEEE OF ANIMALS NECROPSIED 

. ... 

47
 
TABLE A1. MALE RATS: NEOPLASMS (CONTINUED) 

CONTROL LOW DOSE HIGH DOSE
 

TBCCF SUMMAR Y
 

TOTAL ANIMAL S WITH PFI1ARY TUMORS* 5 25 3U
 

TCTAL FPIrlABY TUMOFS 8 33 51
 

TOTAL ANIMALS rflTri BENIGN TUMCPS 5 17 26
 

TCTAL EEMCN TUhOFS 8 23 33
 

TOTAL AMBALS kITh MALIGNANT TUMORS 9 15
 

TCTAL CALIuNAM TUMORS 10 15
 

TCTAL ANIMAL S hITh SECONDARY TUMCFS* 1 2
 

TOTAL SECONDARY TUKCRS 1 2
 

TCTAL ANIMALS HITh TUMORS UNCERTAINEEMGN OR MALIGNAN T 3
 

TCTAL UNCERTAIN TUTORS 3
 

TCTAL ANIMALS fclTH TUMORS UNCERTAINEFIMAPY OP HETASTATIC
 

TCTAL UNCERTAI N TUhORS
 

* PRIMAR Y lUMOhS: ALL TUMORS EXCEPT SECONDARY TUMORS
 * SECCNDARY IUMOBS: METASTATIC TUMORS OR TUMORS INVASIVE INTO AN ADJACENT ORGAN
 

'48
 
TABLE A2.

 

SUMMARY OF THE INCIDENCE OF NEOPLASMS IN FEMALE RATS 

FED PARATHION IN THE DIET 

CONTROL LOW DOSE
 

ANIKAIS INITIALLY IN STUDY 10 50
 

ANIMAL S NECBCPSIED 10 50
 

ANIfoALS EXAMINED HISTOEATHOLOGICALLY 10 50
 

INTEGUfiENTABY SYSTFh
 

*SKIN (10) (50)
 

NEOPLASM, SOS, MALIGNANT
 

*SUPCUT TISSUE (10) (50)
 

C-CELL CARCINOMA, KETASTATIC
 

RrSFISATOHY SYSTEM
 

*LUNG (10) (U9)
 

ALVEOLAR/BEONCHIOLAR ADENOMA
 

C-CEIL CARCINOMA, METASTATIC 1 (10%)
 

HEMATOFOIETIC SYSTEC
 

*FUITIPLE CROAKS (10) (50)
 

LYC.FHOCY1IC LEUKEMIA
 

CSFLEEN (10) (50)
 

SARCCMA, NOS
 

*LY^EH NCCE (10) (<H)
 

HEHANGIOMA 1 (1C%) 1 (2X)
 

#CEPVICAL LYMPH NODE (10) (41)
 

C-CELL CARCINOMA, METASTATIC 1 (10X)
 

CIECULATOPY SYSTEM
 

NONE
 

DIGESTIVE SYSTEM
 

tLIVER (10) («9)
 

HEP.ATOCELLUL.AR ADE£OMA •••.•^.^•.•.•.•.—•— —_­

# KUKEER OF ANIMALS WITH TISSUE EXAMINED BICROSCOPICALLY
 * kUKEEE Of ANIMALS NECROPSIED
 

HIGH DOSE
 

50
 

50
 

49
 

(50)
 

1 (2%)
 

(50)
 

1 (2%)
 

(47)
 

1 (2%)
 

1 (2X)
 

(50)
 

1 (2«)
 

(49)
 

1 (2X)
 

(41)
 

(41)
 

(48)
 

1_I2SI_
 

49
 
TABLE A2. FEMALE RATS: NEOPLASMS (CONTINUED) 

CONTRO L LOW DOSiJ HIG H DOSE 

NiOt'LASTJ C NOUUL C 1 (2X ) 2 (US) 

*BIJ.L DUC T (10) (30) (50)

 

nil!, DUL T ADLNOM A 1 (10*)

 

IjKlNAH Y aYSlt M 

#KIDNu Y (10) C*8) (US)

 

t IlA,iAj<rGi1 A 1 (10X)

 

CNUJCRiN t SYSTE M 

ttPlTUn AiU (8) (38) (39) 

ADENOMA , NU b 2 (25%) 11 (29%) 13 (33X) 

« ADRENA L (10) («7) (<42) 

CORTILA I ADENOM A 1 (10<) M (9X ) 11 (26!i) 

uJKllxAL uARCINON A 2 (U« ) (5%) 

C-CfcLL r/uvCINUHA , Bhi \STAI1C ^ 1 (2X) 

triLOCHi«OauCY'IOMA , HALICNAN T 1 (10%) 

• THYROI D (10) (45) («3) 

F01.LICULAK-CEI.L ADLNOH A 1 (10«) <* (9*) 1 (2X) 

C-CELi. CAKi_INOflft 2 (20*) 2 (US) 3 (7X) 

tPANCf-iiATIC iSLETb (K) (IB) (U9 ) 

ISLtT-CELi. ADtNUH A 1 (10%) 1 (2%) 

I5LE1-CELL CABtlNUH A 1 (2*) 

BttHUDUCIIV E SYSTE M 

*MA««AR Y GLAN D (10) (30) (50) 

ADENOMA , NUS 1 (10*) S (2K) 

PAFILLA6 J ADENOLARCIHOM A 1 (2«) 

FIDS 0,1 A 1 (2X) 1 (2X) 

FIllhOADLNOM A 2 (?0%) 1b (J2X) 8 (16X) 

*UTEi<U a (10) (a 9) (15) 

flUhNOCA IN ADENOlUTOUi) POLY P 1 (2*) 

ENUOHiilhlA L t,IKO(1AL POLY P 1 (10X) '4 (8X) b (1U) 

*OVAH K (10 ) (H5 ) (05)

 

CiSI AUENUCARClNOnA i N03 1

 I2IU 

* HUMbii R OF ANIMAL S W tTH 1I53UE EXAHit.Ct) MICTiOSCOPICALLY 

* NJttbtrt Or' ANltlAL b NbCROPbli D 

t This is considered to be a. benign form of the malignant mixed tumor
 

of the kidney and consists of lipocytes, tubular structures, and
 

fibroblasts in varying proportions.
 

50
 
TABLE A2. FEMALE RATS: NEOPLASMS (CONTINUED) 

NIFVCU S SYSTEM
 

NONE
 

SPECIAL SENSE ORGANS
 

NCl^E
 

MUSCULCSKELEIAL SYSTEM
 

NCNE
 

BGCY CAVITIES
 

*EEFITCNEUM


FIBROUS KISTICCYTCMA, MALIGNANT


ALL CTHFF SYSTEMS
 

*rUITIFLE ORGANS


FIERCUS HISTICCYTOHA, MALIGNANT


AKIKAL CISECSI7ION SUMfcARY
 

ANIMALS INITIALLY IN STUDY


NATOPAL TEATH3


KCRIEUKD SACRIFICE


SCHEDULED SACRIFICE
 

ACCIDENTALLY KILLED
 

TERHINAL SACRIFICE


ANIMAL HISSING
 

a-IKlUDES.A.UT.CJ.iZE.D.A.J.I.JIA.LS


CONTROL


 (10)


 (10)


 10


 3


 7


 LOW DOSE HIGH DOSE
 

 (50)	 (50)
 

1 (2%)
 

 (50)	 (50)
 

1 (2«)
 

 50 50
 

2 5
 

 12 11
 

 36	 34
 

_ _
 

*	 KUKBEF OF ANIMALS KITH TISSUE EXAMINED MICROSCOPICALLY
 

*	 NUMEEP OF ANIMALS NFCROPSIED
 

51
 
TABLE A2. FEMALE RATS: NEOPLASMS (CONTINUED) 

CONTROL LOW DOSE HIGH DOSE
 

TUCCF SUBMAF Y
 

TOTAL ANIKALS WITH PRIMARY TUMORS* 10 31 32
 

TOTAL PRIHAPY TUKCFS 15 54 53
 

TCTAL ANIMALS WITH BENIGN TUMCRS 8 31 25
 

TOTAL ErMGN TUMO&S 12 «<* U2
 

TOTAL ANIMALS KITH KALIGNANT TUMOES 3 9 8
 

TCTAL MALIGNAN T TUKORS 3 9 9
 

TOTAL ANIMALS tilTH SECONDARY TUMOESt 1 1
 

TOTAL SECONDARY TUMORS 2 3
 

TOTAL ANIMALS WITH TUMORS UNCERTAIN­ EENIGN OR MALIGNANT 1 2
 

TCTAL UNCERTAIN TUMCRS 1 2
 

TOTAL ANIMALS WITH TUMORS UNCERTAIN­ EFIMAE Y Ofi METASTATIC
 

TCTAL USCESTAIN TUMORS
 

* FRIHARY TUMORS: ALL TUMORS EXCEPT SECONDARY TUMORS
 

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

52
 
APPENDIX B
 

SUMMARY OF THE INCIDENCE OF NEOPLASMS IN
 

MICE FED PARATHION IN THE DIET
 

53
 
54

 
TABLE B1. 

SUMMARY OF THE INCIDENCE OF NEOPLASMS IN MALE MICE 

FED PAHATHION IN THE DIET 

CONTROL LOW DOSE HIGH DOSE 

AMP/iIS INITIALLY IN STUDY

ANIhAL S NECECFSItD

ANICALS EXAMINE D hlSTCFATHCLOGICALLY

 10

 10

 10

 50

 49

 49

 50 

 1*9 

 48 

IMEGUMENTAE Y SYSTEM 

*£KIN

MALIGNANT MELANOMA

 (10) (49)

 1(2%) 

 (49) 

*£UECUT TISSUE

FIEEOSAECCMA

 (10) (49)

 1 (2%) 

 (49) 

EESPIEATCBY SYSTEK 

*LUNG

ALVECLAfc/BEONCHIOLAP ADENOMA

 (9) (49)

 3 (6%)

 (47) 

5 (11X) 

HFCATCEOIETIC SYSTEM 

#SFIEEN

PAIIG. IYKFHOMA, LYKPHOCYTIC TYPF

 (8) (49)

 1 (2X) 

 (47) 

KEZSENTFRIC L. NODE

KAIIG. LYKFHOKA, LYBPHOCYTIC TYPE

 (10) (35)

 1 (3S) 

 (37) 

•SMALL INTESTINE

KALIG. LYCtHOHA, LYMPHOCYTIC TYEE

 (10) (48)

 1 (2X) 

 (48) 

CIECCLA10RY SYSTEM 

NCNE 

DIGESTIVE SYSTEM 

*LIVEP

KEOPLASIIC NODULE

HI£A2C£EIiUJ.iB_gi££IJiQMl

t NCBEE B OF ANIMAL S WIT H TISSUE

* NUKEFf c OF ANIMAL S NECROPSIED 

 (10) (48)

 1 (10«) 3 (65C)

 i_IJ22l J-iSSl

 EXAMINE D MICROSCOPICALLY 

 (47) 

8 (17%) 

i_L2Sl_ 

55 
TABLE B1. MALE MICE: NEOPLASMS (CONTINUED) 

CONTROL LOW DOSE HIGH DOSE 

UKIKAK Y SYSTEh 

NONE 

fNECCfllNE SYSTEM 

•THYROIC

CABCINCMA.NOS

 (10) (UO)

 1 (3%) 

 (42) 

REPBCCUCTIVF SYSTEM 

NCNE 

NEFVCUS SYSTEM 

NCK; 

SPECIAL SENSE ORGANS 

NCNE 

MOSCOLCSKEltTAL SYSTEM 

NCNE 

BCEY CAVITIES 

KCNE 

ALL CTHER SYSTEMS 

NCJST. ^_ 

* KDREER CF ANIMALS WITH TISSUE EXAMINED MICROSCOPICALLY 

* MJKEF.R OF ANIMALS KECROPSIED 

56
 
TABLE B1. MALE MICE: NEOPLASMS (CONTINUED) 

AMCAl DISfCSITICN SUCCAEY
 

ANIMAL S INITIALLY It. STUDY


NATURA L DEATHa)


MORIBUND SACRIFICE


SCHEDULED SACRIFICE
 

ACCIDENTALLY KILLED
 

1FSMINAL SACPIFICE


AMHA L HISSING
 

d) INCLUDES AUTCLYZED ANIMALS
 

IUKF SUPMAM
 

TCTAL ANIMAL S fclTt- FPIBAPY TUCOBS*


1CTAL ERIMAPY 1UMUFS


ICTAL ANIMALS WITn SFSIGN TUMORS


1CTAL ELMGN TUMORS


TC1AL ANIKALS fclTh MALIGNANT TU("CFS


"•CTAL MALIGNANT 1U^.CRS


10TAL ANIHALS hITH SECONDARY TUHORS*
 

TOTAL SECONDARY TUMORS
 

TOTAL ANIMALS WITH TUMORS UNCERTAIN­ EIMCN OR MALIGNANT


TOTAL UNCEwTAIN TUMORS


TOTAL ANIMAL S WITh TUMORS UNCEPTAIN­ fEIMAFY OR HETASIATIC
 

TCTAL UNCERTAIN TUMORS
 

CONTROL LOW DOSE HIGH DOSE 

 10 50 50 

1 U 

3 6 

 10 46 1*0 

2 14 12 

2 15 1U 

3 5 

3 5 

1 6 1 

1 9 1 

1 3 8 

1 3 8 

* ERIMARY TUMORS: ALL TUMORS EXCEPT SECONDARY TUMORS
 * SECONDARY TUMCES: KETASTATIC TUMORS OR TUMORS INVASIVF INTO AN ADJACENT ORGAN
 

57 
TABLE B2.

 

SUMMARY OF THE INCIDENCE OF NEOPLASMS IN FEMALE MICE 

FED HARATHION IN THE DIET 

CONTROL LOW DOSE HIGH DOSE
 

ANIMALS INITIALLY IN STUDY 10 50 50
 

AMfALS NECRCPSIED 8 U8 U9
 

AKIKALS EXAMINED HISTuFATHOLOGICALLY 8 U8 «9
 

INTIGUHFNTARY SYSTEM
 

*SIECI;T TISSUE (8) (U8) (U9)
 

HECANGIOKA 1 (2«)
 

RFSriFATCHY SYSTEM
 

*LUNG (9) (HI) (U9)
 

ALVr,CLAF/B60KCtiIOLAR ADENOMA 1 (11%) 2 (4«)
 

hEKANGIOSARCOKA, KI7ASTATIC 1 (2X)
 

HEMATCEOIETIC SYSTEM
 

•"MULTIPLE OFGANS (8) (U8) («9)
 

BALIG.LYC PHOHA, LYMPHOCYTIC TYPE 1 (13%) U (8%) 1 (2»)
 

HALIG.LYKPhOMA. HISTIOCYTIC TYPE 1 (2%) 1 (2%)
 

LEUKEMIA, NOS 1 (2%)
 

GEANULOCYTIC LEUKEKIA 1 <2X)
 

*ECM fcARRCW ("*)
 

HEMANGICSABCCKA 1 (25X)
 

*SPLEEN (9) (45) (H9)
 

HE^A^GIOKA 1 (2«)
 

KALIG.LYKPHOHA, LYHPHOCYTIC TYPE 1 (2X)
 

#KICNZY (9) (46) (U9)
 

MALIG. LYSPHOKA, lYhPHOCYTIC TYPE 2 (<*X)
 

ClfrCtlLATOPY SYSTFM
 

__N£NI
 

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

58
 
TABLE B2. FEMALE MICE: NEOPLASMS (CONTINUED) 

CONTROL LOW DOSE HIGH DOSE
 

DIGESTIVE SYSTEM
 

KLIVEF (9) (47) (49)
 

NEOPLASTIC NODULE 1 (11X) 1 (2%) 1 (2X)
 

URINAE Y SYSTEM
 

KCNE
 

ENDOCRINE SYSTEM
 

#FITUITARY (6) (30) (30)
 

ADENOMA. NOS 1 (3X)
 

tTKYROIC (7) (43) (47)
 

FCLLICULAfi-CELL ADENOMA 1 (2X)
 

REFFCDUCIIVE SYSTEK
 

*HAMMAR Y GLAND (8) (48) (49)
 

ADENOHA, NOS 1 (2%)
 

AEFNCCARCINOMA, NOS 1 (2X)
 

HEMANGIOSAECOMA 1 (2X)
 

NEEVCUS SYSTEM
 

KCKE
 

SPECIAL SENSE ORGANS
 

NCNE
 

MUSCULCSKEIETAL SYSTEM
 

NONE
 

BODY CAVITIES
 

KCNE. .. . x ^
 

* KUKBEF OF ANIMALS WITH TISSUE EXAMINED MICROSCOPICALLY
 * MJKdER OF ANIMALS NECROPSIED
 

59 
TABLE B2. FEMALE MICE: NEOPLASMS (CONTINUED) 

ALL C1HER SYSTEMS
 

NCNE
 

ANIFA L CISECSITICN SUtTABY
 

AMBALS INITIALLY IN STUDY


NATDPAL DEATHS


MORIBUND SACRIFICE


SCHEDULED SACRIFICE
 

ACCIDENTALLY KILLED
 

TERMINAL SACEIFICE


AMCAL MISSING
 

d> INCLUDES AUTCLYZEC ANIMALS
 

TUCCF SUMMAR Y
 

TOTAL ANIRALS HITH FEIMASY TOHCRS*


TOTAL FBIMABY TDKOFS


TOTAL ANIMALS WITH BENIGN TUMOtiS


TOTAL EEMGN TUMCRS


TOTAL ANIMALS WITH MALIGNANT TUBCES


TCTAL MALIGNANT TUMORS


TOTAL ANIMALS WITH SECONDARY TUHORS*


TOTAL SECONDARY TUMORS


TOTAL ANIMALS HITH TUHORS UNCERTAIN-
 PENIGh OR MALIGNANT


TCTAL UNCERTAIN TUMORS


TOTAL ANIftALS WITH TUMORS UNCERTAIN­ EFIMAEY OB HETASTATIC
 

TCTAL UNCERTAIN TUPORS
 

CONTROL LOW DOSE HIGH DOSE
 

 10 50 50
 

2 4 3
 

3
 

8 H6 «4
 

3 12 9
 

3 12 12
 

1 1 <*
 

1 1 6
 

1 10 5
 

1 10 5
 

1
 

1
 

1 1 1
 

1 1 1
 

* FRIfARY TUMORS: ALL TUHORS EXCEPT SECONDARY TUHORS
 * SECCNDARY TUHORS: METASTATIC TUHORS OR TUHORS INVASIVE INTO AN ADJACENT ORGAN
 

60
 
APPENDIX C
 

SUMMARY OF THE INCIDENCE OF NONNEOPLASTIC LESIONS
 

IN RATS FED PARATHION IN THE DIET
 

61
 
62

 
TABLE C1.

 

SUMMARY OF THE INCIDENCE OF NONNEOPLASTIC LESIONS IN MALE RATS 

FEDPARATHIONINTHEDIET 

CONTROL
 

ANirAI S IMTIAilY IN STUDY 10
 

ANIMAL S NECKCFSIED 10
 

ANIKALS EXAMINED HISTOFATHCLOGIC ALLY 10
 

INTEGUMFNTAEY SYSTEM
 

*SKIN


ULCER, NCS


*SUECUT TISSUE


ABSCESS, NOS
 

RESPIRATORY SYSTEM
 

CLUNG


ATELEC1ASIS
 

CONGESTION, NOS
 

ECtMA, NCS
 

LIPOIDOSIS
 

ALVEOLAR MACROPHAGF.S
 

HErATCECIETIC SYSTEM
 

*ECNE KAREOW
 

ATROPHY, NOS
 

hYPERPLASIA, NOS
 

tSPLEEN


ACCESSORY SPLEEN
 

THROMBOSIS, NOS
 

CONGESTION, NCS
 

INFARCT, NOS
 

ATROPHY, NOS
 

RYELOID METAPLASIA
 

tlYBFH NODE


INFLAMMATION, ACUTE/CHRONIC
 

#MANDIBULAR L. NODE


.BSiAJJJ
 

 (10)
 

1 (1CX)
 

 (10)
 

 (10)
 

 (10)
 

 (9)
 

 (9)
 

LOW DOSE
 

50
 

50
 

50
 

(50)
 

(50)
 

(50)
 

3 (6%)
 

1 (2X)
 

(1)


1 (100S)
 

(50)
 

1 (2*)
 

1 (2X)
 

1 (2*)
 

1 (2X)
 

(39)
 

(39)
 

HIGH DOSE
 

50
 

U9
 

4»9
 

(<*9)
 

(U9)
 

1 (2X)
 

(48)
 

1 (2X)
 

1 (2X)
 

1 (2X)
 

d)
 

1 (100X
 

(<I7)
 

3 (6%)
 

3 (6X)
 

(3U)
 

1 (3X)
 

(314)
 

l_(iSl.
 

# NUMBER OF ANIMALS WITH TISSUE EXAMINED MICROSCOPICALLY
 

* NOMEER OF ANIMALS NECROPSIED
 

63
 
TABLE C1. MALE RATS: NONNEOPLASTIC LESIONS (CONTINUED) 

CIHCOIATCRY SYSTEM
 

»HF. ART
 

5CAF
 

fcFYCCAFCIUK
 

INFLAMFATICN, ChRCMC
 

INFLAMMATION, CHFOMC FOCAL
 

*AOFTA
 

AKTIBIOSCiEHOSIS, NOS
 

DIGESTIVE SYSTIM
 

»LIVER
 

CONGESTION, NOS
 

hEHCRPhAGi
 

SCAF
 

CIRRHOSIS, 3ILIAEY
 

fETAMCBFrfOSIS FATTY
 

FOCAL CELLULAR CHANGE
 

HEPATCCYTOMEGALY
 

ANGIECTASIS
 

*EILE CUCT
 

PYPfcFPiASIA, NOS
 

KEAKCRFA S
 

INFLAMMATION, ChRCNIC
 F-EIARTFHITIS
 

ATFCFHY, NOS
 

tSTCMACH
 

MINEBALIZATICN
 

URINAR Y SYSTEM
 

tKIDNEY
 

INFLAMKATICN, CHRONIC
 

f KirNEY/EELVIS
 

INFLAMMATION, SUPPURATIVE
 

*UFINARY ELADDEB
 

CAICULOS, NOS
 

JiI£E££lAJliJ._££lliiEi.l4i!
 

# NUflEE R OF ANIMAL S WIT H TISSUE

* KUM5F R OF ANIMAL S NECROPSIED 

CONTROL LOW DOSE
 

(10)	 (50)
 

1 (2%)
 

(10)	 (50)
 

1 (2%)
 

(10) (50)
 

(10)	 (50)
 

1 (2%)
 

1 (2%)
 

1 (251)
 

1 (10%)
 

2 (4%)
 

1 (2%)
 

1 (2%)
 

1 (2%)
 

(10)	 (50)
 

1 (K%)
 

(9)	 (49)
 

1 (2X)
 

1	 (11%)
 

(10) («2)
 

(10)	 (48)
 

6 (60%) 7 (15*)
 

(10)	 (U8)
 

1 (2%)
 

(9)	 («2)
 

1 (2X)
 

1_I2*1
 

 EXAMINE D MICROSCOPICALLY 

64 

HIGH DOSE
 

(U8)
 

(48)
 

1 (2%)
 

3 (6%)
 

(49)
 

1 (2*)
 

(49)
 

1 (2X)
 

3 (6%)
 

2 (4%)
 

5 (10%)
 

(49)
 

(46)
 

1 (2%)
 

4 (9X)
 

1 (2X)
 

(46)
 

1 (2X)
 

0*8)
 

9 (19X)
 

(48)
 

(41)
 

l_12ii_
 
TABLE C1. MALE RATS: NONNEOPLASTIC LESIONS (CONTINUED)

 

ENLOCFINE SYSTEM
 

frFITUITARY
 

CYST, NOS
 

MULTIPLE CiSIS
 

f ADRENA L
 

THHOMBCSIS, NOS
 

ANGIhCTASIS
 

#FAFATHYROIC
 

HYEFFPLAEIA, NOS
 

REPRODUCTIVE SYSTEM
 

tERCSIATE
 

INFLAMfATICN, CHRONIC
 

HESIIS
 

EEEKA, NCS
 

AIRCPHY, NOS
 

NIRVCUS SYSTEM
 

NCfc?
 

SPECIAL SENSE ORGANS
 

NCNE
 

MUSCULCSKEIETAL	 SYSTEM
 

*EONii
 

EXCSTOSIS
 

*PALAT1NE BONE
 

FRACTURE, NOS
 

BOCY CAVITIES
 

*KES£NTERY
 

£lBIA2!ESilI£
 

CONTROL LOW DOSE HIGH DOSE
 

(9)	 (U2) (43)
 

1	 (2%)
 

1 (2%)
 

(9)	 (49) (1*6)
 

1 (2%)
 

1 (2*)
 

(5)	 (3«) (29)
 

2 (7%)
 

(10)	 (HU) (1*6)
 

3 (7«) 1 (2X)
 

(10)	 (U7) (1*8)
 

9 (19%) 2 (U%)
 

1 (1C*) H (9X) 2 (US)
 

(10)	 (50) (U9)
 

1 (IPX)
 

(10)	 (50) (1*9)
 

1 (10%)
 

(10)	 (50) (49)
 

l_il£4L . _2_Jlil_
 

t	 NUMEEK OF ANIMALS WITH TISSUE EXAMINED MICROSCOPICALLY
 * NUMEEE OF ANIMALS NECROPSIED
 

65 
TABLE U1. MALE RATS: NONNEOPLASTIC LESIONS (CONTINUED) 

CONTROL LOW DOSE HIGH DOSE 

*TtNIC A VAGINALI S (10) (50) (49) 

HYFERFLASIA , NOS 1 (2%) 

A L L CTHE K SYSTEM S 

!>CNF 

SPECIA L MOt-FBOLOG Y SL'hMAR Y 

hC LESIC N PEEOKTEE 2 10 U 

AUTCLYSIS/N C KECPOFS Y 1 

# MJKEF R CF ANIMAL S fcll H TISSU E EXAMINE D MICROSCOPICALL Y 

* MJftEF P OF ANIMAL S NECROPSIE D 

66 
TABLE C2. 

SUMMARY OF THE INCIDENCE OF NONNEOPLASTIC LESIONS IN FEMALE RATS 

FED PARATHION IN THE DIET 

CONTROL LOW DOSE HIGH DOSE
 

ANIMALS IMTIAIIY IN STUDY 1C 50 50
 

ANIMALS NECBCPSIED 10 50 50
 

ANIMALS EXAMINED HISTCFATHOLOGICALLY 10 50 U9
 

INTEGUMENTARY SYSTEM
 

*SKIN (10) (50) (50)
 

ULCER, NOS 1 <2X) 1 (2%)
 

ULCEE, FOCAL 2 (U)
 

FIEROSIS 3 (6X)
 

ACANTHOSIS 2 (4%)
 

RESPIRATORY SYSTEM
 

NCNE
 

HEMATCFOIETIC SYSTEM
 

#ECNE HARROW (2) (2)
 

HYPOFLASIA, NOS 1 (50X)
 

HIPEEPLASIA, NOS 1 (50%) 1 (50X)
 

HYPERPLASIA, ERYTHROID 1 (SOX)
 

#SPtEZN (10) (50) (U9)
 

HYFEBPLASIA, FOCAL 2 C»X)
 

#THY8US (13) (5)
 

ULTIMOBRANCHIAL CYST 2 (15X)
 

CIECUIATORY SYSTEM
 

#MYCCARDIUM (10) (50) (»9)
 

IMFIAHBATICN, CHPONIC 2 («X)
 

DIGESTIVE SYSTEM
 

»LIVER (10) (U9) (<»8)
 

CETAMORPHOSIS PAJ2I_ ^-._mm ,_ _. 3 (§81 3 J6$l
 

# kOBEER OF ANIHALS WITH TISSUP EXAMINED MICROSCOPICALLY
 

* NUMBER OF ANIMALS NECROPSIED
 

67
 
TABLE C2. FEMALE RATS: NONNEOPLASTIC LESIONS (CONTINUED) 

JCCAL CELLULAR CHANGE
 

*EIIE DUCT


HYPERPLASIA, NOS
 

tSTCMACH


MNE8ALIZATION
 

UEIKAEY SYSTEM
 

IKIDNEY


INFLAMMATION, CHRONIC


INFAECT, NOS
 

#KICNEY/PELVIS


INFLAMMATION, SUEPURATIVE


ENEOCBINE SYSTEM
 

fADRENAL


ANGIECTASIS


tTHYROID


HYFERPLASIA, FOLLICULAR-CELL
 

HEFECCUCTIVE SYSTEM
 

*«AMMARY GLAND


NECROSIS, CENTRAL
 

#UTERUS


HYEROMETRA
 

CYST, NOS
 

tUlEROS/ENDOMETRIUM


HYPEHPIASIA, CYSTIC
 

NEEVCUS SYSTEM
 

NONE
 

SPECIAL SENSE ORGANS
 

--ISSUE.
 

CONTROL
 

 (10)
 

 (10)
 

 (10)
 

1 (10X)
 

 (10)
 

1 (10%)
 

 (10)
 

1 (10X)
 

 (10)
 

 (10)
 

 (10)
 

 (10)
 

LOW DOSE
 

1 (2%)
 

(50)
 

1 (2X)
 

C*8)
 

(48)
 

2 (MX)
 

1 (2X)
 

(<48)
 

(147)
 

2 (4X)
 

(US)
 

1 (2X)
 

(50)
 

1 (2X)
 

C*9)
 

1 (2X)
 

2 («)
 

(i«9)
 

1 (2X>
 

HIGH DOSE
 

1 (2X)
 

(50)
 

(«7)
 

1 (2X)
 

(48)
 

1 OX)
 

(<*8)
 

{U2)
 

(«3)
 

(50)
 

0»5)
 

(*»5)
 

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

68
 
TABLE C2. FEMALE RATS: NONNEOPLASTIC LESIONS (CONTINUED)

 

CONTROL LOW DOSE HIGH DOSE 

MUSCULCSKEIETAL SYSTEM 

NONE 

BOCY CAVITIES 

NONE 

ALI CTHER SYSTEMS 

GASTROSPLENIC LIGABE 

NECROSIS. FAT 1 

SPECIAL MORPHOLOGY SUMMARY 

# KU£EER CF ANIMALS WI1H TISSUE EXAHINED MICROSCOPICALLY 

* NUHBEE OF ANIMALS NECROPSIED 

NO LESION REPORTED 13

AOTO/NECBOPSY/NO HISTO

 1« 

1 

69
 
70

 
APPENDIX D 

SUMMARY OF THE INCIDENCE OF UONNEOPLASTIC LESIONS
 

IN MICE FED PARATHION IN THE DIET
 

•71 
72

 
TABLE 01. 

SUMMARY OF THE INCIDENCE OF NONNEOPLASTIC LESIONS IN MALE MICE 

FED PARATHION IN THE DIET 

CONTROL LOW DOSE HIGH DOSE
 

ANICAIS INITIALLY IN STUEY 10 50 50
 

ANIKAL S NECECESIED 10 49 49
 

ANIMALS EXAMINEE HI3TCPATHOLOGICALLY 10 49 48
 

INTEGUMENTARY SYSTEM
 

*SKIN (10) (49) (49)
 

ABSCESS, NOS 1 (2%)
 

INFLAMMATION, CHRONIC 1 (10S)
 

RESPIRATORY SYSTEM
 

NCNE
 

HEEATCFCIETIC SYSTEM
 

fcECNE MARRO h (2) (1)
 

hYPERPLASIA, HEMATOPOI ETIC 1 (100X)
 

*KESENTERIC L. NODI (10) (35) (37)
 

HEMORRHAGE 2 (68)
 

INFLAMMATION, GR ANULOHATODS 1 (3X)
 

CIECD1ATCBY SYSTEM
 

NCNE
 

DIGESTIVE SYSTEM
 

#LIVER (10) (48) (<»7)
 

NECROSIS, FOCAL 1 (2%)
 

EASOPHIL1C CYTO CHANGE 1 (2%)
 

ANGIECTASIS 1 (2%) 1 (2X)
 

UEINARY SYSTEM
 

#KIEhEY/PELVIS (10) (49) (H8)
 

INFLAHBATIONX SUg£Uj?A.I!VE ^ , ... . - _._ ^1 ,(2X1
 

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

73 
TABLE D1. MALE MICE: NONNEOPLASTIC LESIONS (CONTINUED) 

ttURINAR Y BLADDER


INFLAMMATION, SUPE-URATIVE


ENEOCRINE SYSTEM
 

NCN E
 

REPRODUCTIVE SYSTEM
 

*EFEPUTIAL GLAND


CYST, NOS


*E?CSTATE


INFLAMMATION, SUFPUHATIVE


NEBVCUS SYSTEM
 

NONE
 

SPECIAL SENSE ORGANS
 

NCNE
 

MUSCULOSKELETAL SYSTEM
 

NCNE
 

BODY CAVITIES
 

NONE
 

ALL CTHEB SYSTEMS
 

NONE
 

SPECIAL MORPHOLOGY SUMMARY
 

NO LESION REEORTED


AUTC/NECROPSY/NO HISTO


—iflli2lI£I^ULJU££fi£SJL —


CONTROL LOW DOSE HIGH DOSE
 

(1)	 (41) (45)
 

2 (4X)
 

(10)	 (49) (49)
 

1 (2X)
 

(9)	 (U2) (43)
 

2 (5X)
 

7 31 31
 

1
 

1.. 1,
 ff KOMEE KOMEERR OOPF ANIMAL ANIMALSS HTT WITHH TISSU TTSSOEE EXJkM EXAHI»2 T «2DD MICROSCOPICALL MT rfiOSCOPICALL
Y
 Y

* NL'MEEK OF ANIMALS NECROPSIED
 

74 
TABLE D2. 

SUMMARY OF THE INCIDENCE OF NONNEOPLASTIC LESIONS IN FEMALE MICE 

FED PARATHION IN THE DIET 

CONTROL LOW DOSE HIGH DOSE
 

ANIMAL S INITIALLY IN STUDY 10 50 50
 

ANIMALS NECKOPSIED 8 48 49
 

ANIMALS EXAMINED HISTOEATHpLOGICALLY 8 48 49
 

INTEGUMENTARY SYSIEH
 

NCNf
 

RFSPIFATORY SYSTEM
 

CLUNG (9) (U7) (49)
 

GRANULCKA, PYOGENIC 1 (2*)
 

BETAPLASIA, OSSEOUS 1 <2X)
 

HEBATCEOIETIC SYSTEM
 

*EONE HARROW («)


HYFEPPLASIA, HEMATOPOIETIC 3 (7SX)
 

(tSFLIEN (9) (45) (49)
 

INFARCT, NOS 1 (2X)
 

KYFLOID METAPLASIA 1 (2%)
 

«LYKPH NODE (6) («2) (47)
 

ABSCESS, NOS 1 (2X)
 

#CEEVICAL LYHPH NODE (6) (42) (47)
 

IKFLAHMATICN, SUEFURATIVE 1 (2X)
 

#«EEIASTINAL L.NODE (6) (*2) (47)
 

GEANULCHA, PYOGENIC 1 (2X)
 

#KESENTERIC L. NODE (6) (*2) («7)
 

GRANULCMA, PYOGENIC 1 (2%)
 

CIBCULA10HY SYSTEM
 

JiCKE.--. -r- ,- - -, ^,,» r, .. | ^+_±
• i T- A- IT' r
 

* NUMBER OF AKIHALS KITH TISSUE EXAMINED HICBOSCOPICAttT
 

* KUHEER OF ANIMALS NECROPSIED
 

75
 
TABLE D2. FEMALE MICE: NONNEOPLASTIC LESIONS (CONTINUED) 

DIGESTIVE SYSTEM
 

#LIVEP
 

EASCEHILIC CYTO CHANGE
 

IFANCREAS
 

CYST, NOS
 

ATROPHY, NOS
 

UPINAR Y SYSTEM
 

»KIENEY
 

CYST, NOS
 

INFLAMMATION, CHPCNIC
 

*UFINAF-Y ELADEER
 

INFLAMMATION, CHRCMC
 

ENEOCEINE SYSTEM
 

NON E
 

RIFECCUCTIVE SYSTEM
 

*MAMHARY GLAND
 

METAPLASIA, C3SICUS
 

#UTEEUS
 

INFLAMMATION, SUFPURATIVE
 

EYOHETRA
 

ABSCISS, NOS
 

#CVARY
 

INFLAMMATION, SUFEURATIVE
 

AESCESS, NOS
 

INFLAMMATION, CffcONIC
 

NEEVCUS SYSTEM
 

NONE
 

SPECIAL SENSE ORGANS
 

N^NE
 

# NUMBE R OF ANIMAL S HUH TISSUE

* MJNEFfi OF ANIMAL S NECROPSIED 

CONTROL LOW DOSE HIGH DOSE
 

(9)	 (U7) (49)
 

3 (6*)
 

(7)	 (47) (48)
 

1 (14X) 1 (2X)
 

1 (14%) 1 (2%)
 

(9)	 (46) (49)
 

1 (2X)
 

2 (UX)
 

(34)	 (40)
 

1 (3%)
 

(8)	 (48) (49)
 

1 (2X)
 

(7)	 (46) (47)
 

1 (2X)
 

2 (4X)
 

1 (2X) 2 (4X)
 

(6)	 (42) (45)
 

1 (2%)
 

9 (21X) 4 (9X)
 1	 <m>
 

 EXAMINE D MICROSCOPICALLY 

76 
TABLE D2. FEMALE MICE: NONNEOPLASTIC LESIONS (CONTINUED) 

CONTROL LOW DOSE HIGH DOSE 

KUSCIHCSKEIETAI SYSTEM 

NCNE 

BCEY CAVITIES 

NCNE 

ALI CTHER SYSTEMS 

KCNE 

SPECIAL MORPHOLOGY SUMMARY 

NO LESION EEPORTiD 3 21

AUTOLYSIS/NO NECROPSY 2 2

# hUKEER OF ANIKALS WITH TISSOE EXAMINED BICROSCCPICALLY 

* KOREER OF ANIHALS NECROPSIED 

 32 

1 

77 
78

 
APPENDIX E
 

ANALYSES OF THE INCIDENCE OF PRIMARY TUMORS
 

IN RATS FED PARATHION IN THE DIET
 

79
 
80

 
__ 

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

Fed Parathion in the Diet (a)
 

Topography: Morphology

Pooled 

 Control 

Liver: Hepatocellular Carcinoma, 

Hepatocellular Adenoma, or 

Neoplastic Nodule (b) 3/85 (4) 

P Values (c,d) N.S. 

Relative Risk (Pooled Control) (f) 

Lower Limit 

Upper Limit 

00 

M 

Relative Risk (Matched Control) (f) 

Lower Limit 

Upper Limit 

Weeks to First Observed Tumor 

Pituitary: Chromophobe Adenoma 

or Adenoma, NOS (b) 21/72 (29) 

P Value (c,d) N.S. 

Relative Risk (Pooled Control) (f) 

Lower Limit 

Upper Limit 

Relative Risk (Matched Control) (f) 

Lower Limit 

Upper Limit 

Weeks to First Observed Tumor 92


Matched


Control


0/10 (0)


N.S.


—
 

4/9 (44)


N.S.


 Low
 

 Dose
 

 0/50 (0)
 

 N.S.
 

0.000
 

0.000
 

2.833
 

—
 

—
 

 10/42 (24)
 

 N.S.
 

0.816
 

0.377
 

1.612
 

0.536
 

0.230
 

1.988
 

 100
 

High
 

Dose
 

4/49 (8)
 

N.S.
 

2.313
 

0.406
 

15.125
 

Infinite
 

0.211
 

Infinite
 

112
 

13/43 (30)
 

N.S.
 

1.037
 

0.529
 

1.914
 

0.680
 

0.312
 

2.420
 

112
 
Table El. Analyses of the Incidence of Primary Tumors in Male Rats
 

Fed Parathion in the Diet (a)
 

(continued)
 

Pooled Matched Low
 

Topography: Morphology Control Control Dose
 

Adrenal: Cortical Adenoma (b) 2/80 (3) 0/9 (0) 5/49 (10)
 

P Values (c,d) P = 0.001 N.S. N.S.
 

Relative Risk (Pooled Control) (f) 4.082
 

Lower Limit 0.696
 

Upper Limit 41.364
 

Relative Risk (Matched Control) (f) Infinite 

Lower Limit 0.262 

CD Upper Limit Infinite NJ 

Weeks to First Observed Tumor — 112
 

Adrenal: Cortical Adenoma
 

or Carcinoma (b) 3/80 (4) 0/9 (0) 7/49 (14)
 

P Values (c,d) P less than P = 0.048 P = 0.035**
 

0.001
 

Relative Risk (Pooled Control) (f) 3.810
 

Lower Limit 0.914
 

Upper Limit 21.780
 

Relative Risk (Matched Control) (f) Infinite
 

Lower Limit 0.404
 

Upper Limit Infinite
 

Weeks to First Observed Tumor 85
 

High
 

Dose
 

9/46 (20)
 

P = 0.002**
 

7.826
 

1.707
 

71.374
 

Infinite
 

0.584
 

Infinite
 

91
 

11/46 (24)
 

P less than
 

0.001**
 

6.377
 

1.789
 

33.667
 

Infinite
 

0.738
 

Infinite
 

91
 
Table El. Analyses of the Incidence of Primary Tumors in Male Rats
 

Fed Parathion in the Diet (a)
 

(continued)
 

Pooled Matched Low
 

Topography: Morphology Control Control Dose
 

Thyroid: Follicular-cell
 

Adenoma (b) 5/76 (7) 3/10 (30) 2/46 (4)
 

P Values (c,d) P = 0.037 N.S. P = 0.035* (N)
 

Departure from Linear Trend (e) P = 0.010
 

Relative Risk (Pooled Control) (f) 0.661
 

Lower Limit 0.065
 

Upper Limit 3.830
 

Relative Risk (Matched Control) (f) 0.145
 

Lower Limit 0.015
 

oo
 

u> Upper Limit 1.150
 

Weeks to First Observed Tumor 95 112
 

Pancreatic Islets: Islet-Cell
 

Carcinoma (b) 0/79 (0) 0/9 (0) 1/49 (2)
 

P Values (c,d) P = 0.024 N.S. N.S.
 

Relative Risk (Pooled Control) (f) Infinite
 

Lower Limit 0.086
 

Upper Limit Infinite
 

Relative Risk (Matched Control) (f) Infinite
 

Lower Limit 0.011
 

Upper Limit Infinite
 

Weeks to First Observed Tumor 112
 

High
 

Dose
 

8/43 (19)
 

P = 0.046**
 

2.828
 

0.868
 

10.237
 

0.620
 

0.201
 

3.239
 

95
 

3/46 (7)
 

P = 0.048**
 

Infinite
 

1.024
 

Infinite
 

Infinite
 

0.133
 

Infinite
 

95
 
Table El. Analyses of the Incidence of Primary Tumors in Male Rats
 

Fed Parathion in the Diet (a)
 

(continued)
 

(a) Dosed groups received time—weighted average doses of 32 or 63 ppm.
 

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

(c) Beneath the incidence of tumors in a control group is the probability level for the Cochran-


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

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

the comparison of that dosed group with the matched-control group (*) or with the pooled-


control group (**) when P less than 0.05 for either control group; otherwise, not significant
 

(N.S.) is indicated.
 

(d) A negative trend (N) indicates a lower incidence in a dosed group than in a control group.
 

.(e) The probability level for departure from linear trend is given when P less than 0.05 for any
 oo
 *> comparison.
 

(f) The 95% confidence interval of the relative risk between each dosed group and the specified
 

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

Fed Parathion in the Diet (a)
 

Pooled Matched Low
 

Topography: Morphology Control Control Dose
 

Liver: Neoplastic Nodule or
 

Hepatocellular Adenoma (b) 5/84 (6) 0/10 (0) 1/49 (2)
 

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

Relative Risk (Pooled Control) (f) 0.343
 

Lower Limit 0.007
 

Upper Limit 2.929
 

Relative Risk (Matched Control) (f) Infinite
 

Lower Limit 0.012
 

oo Upper Limit Infinite
 Ln
 

Weeks to First Observed Tumor 112
 

Pituitary: Chromophobe Adenoma
 

or Adenoma, NOS (b) 25/75 (33) 2/8 (25) 11/38 (29)
 

P Values (c/d) N.S. N.S. N.S.
 

Relative Risk (Pooled Control) (f) 0.868
 

Lower Limit 0.429
 

Upper Limit 1.601
 

Relative Risk (Matched Control) (f) 1.158
 

Lower Limit 0.355
 

Upper Limit 9.741
 

Weeks to First Observed Tumor 105 89
 

High
 

Dose
 

3/48 (6)
 

N.S.
 

1.050
 

0.169
 

5.121
 

Infinite
 

0.139
 

Infinite
 

109
 

13/39 (33)
 

N.S.
 

1.000
 

0.526
 

1.766
 

1.333
 

0.424
 

11.002
 

93 
Table E2. Analyses of the Incidence of Primary Tumors in Female Rats
 

Fed Parathion in the Diet (a)
 

(continued)
 

Pooled Matched
 

Topography: Morphology Control Control
 

Adrenal: Cortical Adenoma (b) 4/78 (5) 1/10 (10)
 

P Values (c,d) P = 0.001 P = 0.037
 

Relative Risk (Pooled Control) (f)
 

Lower Limit
 

Upper Limit
 

Relative Risk (Matched Control) (f)
 

Lower Limit
 

Upper Limit
 

CD
 

CM Weeks to First Observed Tumor 98
 

Adrenal: Cortical Adenoma
 

or Carcinoma (b) 4/78 (5) 1/10 (10)
 

P Values (c,d) P less than P = 0.028
 

0.001
 

Relative Risk (Pooled Control) (f)
 

Lower Limit
 

Upper Limit
 

Relative Risk (Matched Control) Cf)
 

Lower Limit
 

Upper Limit
 

Weeks to First Observed Tumor 98
 

Low
 

Dose
 

4/47 (9)
 

N.S.
 

1.660
 

0.322
 

8.460
 

0.851
 

0.103
 

41.020
 

112
 

6/47 (13)
 

N.S.
 

2.489
 

0.621
 

11.349
 

1.277
 

0.192
 

57.405
 

112
 

High
 

Dose
 

11/42 (26)
 

P = 0.001**
 

5.107
 

1.620
 

20.469
 

2.619
 

0.479
 

109.307
 

65
 

13/42 (31)
 

P less than
 

0.001**
 

6.036
 

2.005
 

23.541
 

3.095
 

0.587
 

127.253
 

65
 
00 

Table E2.


(continued)
 

Topography: Morphology


Thyroid: Follicular-cell
 

Adenoma (b)


P Values (c,d)


Relative Risk (Pooled Control) (f)
 

Lower Limit
 

Upper Limit
 

Relative Risk (Matched Control) (f)
 

Lower Limit
 

Upper Limit
 

Weeks to First Observed Tumor
 

Thyroid: C-cell Carcinoma (b)


P Values (c,d)


Relative Risk (Pooled Control) (f)
 

Lower Limit
 

Upper Limit
 

Relative Risk (Matched Control) (f)
 

Lower Limit
 

Upper Limit
 

Weeks to First Observed Tumor
 

 Analyses of the Incidence of Primary Tumors in Female Rats
 

Fed Parathion in the Diet (a)
 

Pooled Matched Low 

 Control Control Dose 

 3/80 (4) 1/10 (10) 4/45 (9) 

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

2.370 

0.417 

15.439 

0.889 

0.108 

42.792 

112 84 

 7/80 (9) 2/10 (20) 2/45 (4) 

 N.S. N.S. N.S 

0.508 

0.053 

2.517 

0.222 

0.019 

2.871 

98 84 

High
 

Dose
 

1/43 (2)
 

N.S.
 

0.620
 

0.012
 

7.400
 

0.233
 

0.003
 

17.864
 

113
 

3/43 (7)
 

N.S.
 

0.797
 

0.138
 

3.274
 

0.349
 

0.050
 

3.897
 

103
 
Table E2. Analyses of the Incidence of Primary Tumors in Female Rats
 

Fed Parathion in the Diet (a)
 

(continued)
 

Topography: Morphology


Mammary Gland: Fibr oadenoma (b)


P Values (c,d)


Departure from Linear Trend (e)


Relative Risk (Pooled Control) (f)
 

Lower Limit
 

Upper Limit
 

Relative Risk (Matched Control) (f)
 

Lower Limit
 

oo
 

00 Upper Limit
 

Weeks to First Observed Tumor
 

Uterus: Endometrial Stromal
 

Polyp (b)


P Values (c,d)


Relative Risk (Pooled Control) (f)
 

Lower Limit
 

Upper Limit
 

Relative Risk (Matched Control) (f)
 

Lower Limit
 

Upper Limit
 

Weeks to First Observed Tumor
 

Pooled Matched Low 

 Control Control Dose 

 9/85 (11) 2/10 (20) 16/50 (32) 

 N.S. N.S. P = 0.002** 

 P = 0.004 

3.002 

1.362 

7.077 

1.600 

0.493 

13.259 

90 57 

 9/82 (11) 1/10 (10) 4/49 (8) 

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

0.744 

0.175 

2.497 

0.816 

0.099 

39.389 

98 112 

High
 

Dose
 

8/50 (16)
 

N.S.
 

1.511
 

0.539
 

4.098
 

0.800
 

0.207
 

7.210
 

80
 

5/45 (11)
 

N.S.
 

1.012
 

0.280
 

3.126
 

1.111
 

0.154
 

51.348
 

112
 
Table E2. Analyses of the Incidence of Primary Tumors in Female Rats
 

Fed Parathion in the Diet (a)
 

(continued)
 

(a) Dosed groups received time-weighted average doses of 23 or 45 ppm.
 

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

(c) Beneath the incidence of tumors in a control group is the probability level for the Cochran-


Armitage test when P less than 0.05; otherwise, not significant (N.S.) is indicated.
 

Beneath incidence of tumors in a dosed group is the probability level for the Fisher exact
 

test for the comparison of that dosed group with the matched-control group (*) or with the
 

pooled-control group (**) when P less than 0.05 for either control group; otherwise, not
 

significant (N.S.) is indicated.
 

(d) A negative trend (N) indicates a lower incidence in a dosed group than in a control group.
 00 

vfi 

(e) The probability level for departure from linear trend is given when P less than 0.05 for any
 

comparison.
 

(f) The 95% confidence interval of the relative risk between each dosed group and the specified
 

control group.
 
90

 
APPENDIX F
 

ANALYSES OF THE INCIDENCE OF PRIMARY TUMORS
 

IN MICE FED PARATHION IN THE DIET
 

91
 
92

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

Fed Parathion in the Diet (a)
 

Pooled Matched Low
 

Topography: Morphology Control Control Dose
 

Lung: Alveolar/Bronchiolar
 

Adenoma (b) 10/126 (8) 0/9 (0) 3/49 (6)
 

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

Relative Risk (Pooled Control) (f) 0.771
 

Lower Limit 0.140
 

Upper Limit 2.828
 

Relative Risk (Matched Control) (f) Infinite
 

Lower Limit 0.125
 

vo Upper Limit Infinite
 

Weeks to First Observed Tumor 89
 

Liver: Hepatocellular
 

Carcinoma (b) 21/127 (17) 1/10 (10) 3/48 (6)
 

P Values (c,d) P = 0.003 (N) N.S. N.S.
 

Relative Risk (Pooled Control) (f) 0.378
 

Lower Limit 0.074
 

Upper Limit 1.184
 

Relative Risk (Matched Control) (f) 0.625
 

Lower Limit 0.061
 

Upper Limit 32.146
 

Weeks to First Observed Tumor 90 67
 

High
 

Dose
 

5/47 (11)
 

N.S.
 

1.340
 

0.374
 

4.026
 

Infinite
 

0.274
 

Infinite
 

90
 

1/47 (2)
 

P = 0.006** (N)
 

0.129
 

0.003
 

0.758
 

0.213
 

0.003
 

16.378
 

85
 
Table Fl. Analyses of the Incidence of Primary Tumors in Male Mice
 

Fed Parathion in the Diet (a)
 

(continued)
 

Pooled Matched
 

Topography: Morphology Control Control
 

Liver: Hepatocellular Carcinoma,
 

Hepatocellular Adenoma, or
 

Neoplastie Nodule (b) 27/127 (21) 2/10 (20)
 

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

Relative Risk (Pooled Control) (f)
 

Lover Limit
 

Upper Limit
 

Relative Risk (Matched Control) (f)
 NO 

*• Lower Limit 

Upper Limit 

Weeks to First Observed Tumor	 90
 

Hematopoietic System: Lymphoma (b) 3/133 (2) 0/10 (0)
 

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

Relative Risk (Pooled Control) (f)
 

Lower Limit
 

Upper Limit
 

Relative Risk (Matched Control) (f)
 

Lower Limit
 

Upper Limit
 

Weeks to First Observed Tumor
 

Low
 

Dose
 

6/48 (13)
 

N.S.
 

0.588
 

0.209
 

1.340
 

0.625
 

0.144
 

5.907
 

67
 

3/49 (6)
 

N.S.
 

2.714
 

0.373
 

19.485
 

Infinite
 

0.136
 

Infinite
 

89
 

High
 

Dose
 

9/47 (19)
 

N.S.
 

0.901
 

0.357
 

1.79&
 

0.957
 

0.258
 

8.460
 

0/48 (0)
 

N.S.
 

0.000
 

0.000
 

4.617
 

—
 

—
 

—
 

85 
Table Fl. Analyses of the Incidence of Primary Tumors in Male Mice
 

Fed Parathion in the Diet (a)
 

(continued)
 

(a) Dosed groups received 80 or 160 ppm.
 

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

(c) Beneath the incidence of tumors in a control group is the probability level for the Cochran-


Armitage test when P less than 0.05; otherwise, not significant (N.S.) is indicated.
 

Beneath the incidence of tumors in a dosed group is the probability level for the Fisher exact
 

test for the comparison of that dosed group with the matched-control group (*) or with the
 

pooled-control group (**) when P less than 0.05 for either control group; otherwise, not
 

significant (N.S.) is indicated.
 

(d) A negative trend (N) indicates a lower incidence in a dosed group than in a control group.
 

(e) The probability level for departure from linear trend is given when P less than 0.05 for any
 

comparison.
 

(f) The 95% confidence interval of the relative risk between each d< ad group and the specified
 

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

Fed Parathion in the Diet (a)
 

Pooled Matched
 

Topography: Morphology Control Control
 

Lung: Alveolar/Bronchiolar
 

Adenoma (b) 3/128 (2) 1/9 (11)
 

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

Relative Risk (Pooled Control) (f)
 

Lower Limit
 

Upper Limit
 

Relative Risk (Matched Control) (f)
 

Lower Limit
 

Upper Limit
 

VO 

Weeks to First Observed Tumor 90
 

Liver: Neoplastic Nodule or
 

Hepatocellular Adenoma (b) 3/126 (2) 1/9 (11)
 

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

Relative Risk (Pooled Control) (f)
 

Lower Limit
 

Upper Limit
 

Relative Risk (Matched Control) (f)
 

Lower Limit
 

Upper Limit
 

Weeks to First Observed Tumor 90 

Low
 

Dose
 

0/47 (0)
 

N.S.
 

0.000
 

0.000
 

4.535
 

0.000
 

0.000
 

3.585
 

—
 

1/47 (2)
 

N.S.
 

0.894
 

0.017
 

10.722
 

0.191
 

0.003
 

14.743
 

89 

High
 

Dose
 

2/49 (4)
 

N.S.
 

1.742
 

0.148
 

14.637
 

0.367
 

0.023
 

21.260
 

90
 

1/49 (2)
 

N.S.
 

0.857
 

0.016
 

10.298
 

0.184
 

0.003
 

14.153
 

90 
Table F2. Analyses of the Incidence of Primary Tumors in Female Mice
 

(continued)
 

Topography: Morphology

Hematopoietic System: Lymphotna (b)

P Values (c,d)

Relative Risk (Pooled Control) (f) 

Lower Limi t 

Upper Limit 

Relative Risk (Matched Control) (f) 

Lower Limit 

VO Upper Limi t •vl
 

Weeks to First Observed Tumor

Hematopoietic System: Lymphotna 

or Leukemia (b)

P Values (c,d)

Relative Risk (Pooled Control) (f) 

Lower Limit 

Upper Limi t 

Relative Risk (Matched Control) (f) 

Lowe r Li mi t 

Upper Limit 

Weeks to First Observed Tumor

Fed Parathion in the Diet (a)
 

Pooled Matched 

 Control Control 

 13/128 (10) 1/9 (11) 

 N.S. N.S. 

 90 

 14/128 (11) I/ O (11) 

 N.S. N.S. 

 90

Low 

Dose 

7/48 (15) 

N.S. 

1.436 

0.510 

3.592 

1.313 

0.215 

57.828 

89 

8/48 (17) 

N.S. 

1.524 

0.585 

3.595 

1.500 

0.258 

65.028 

 88

High 

Dose 

3/49 (6) 

N.S. 

0.603 

0.113 

2.065 

0.551 

0.055 

28.360 

85 

4/49 (8) 

N.S. 

0.746 

0.185 

2.226 

0.735 

0.091 

35.451 

 85 
Table F2. Analyses of the Incidence of Primary Tumors in Female Mice
 

Fed Parathion in the Diet (a)
 

(continued)
 

(a) Dosed groups received 80 or 160 ppm.
 

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

(c) Beneath the incidence of tumors in a control group is the probability level for the Cochran-


Armitage test when P less than 0.05; otherwise, not significant (N.S.) is indicated.
 

Beneath the incidence of tumors in a dosed group is the probability level for the Fisher exact
 

test for the comparison of that dosed group with the matched-control group (*) or with the
 

pooled-control group (**) when P less than 0.05 for either control group; otherwise, not
 

significant (N.S.) is indicated.
 

VO 

oo
 (d) A negative trend (N) indicates a lower incidence in a dosed group than in a control group.
 

(e) The probability level for departure from linear trend is given when P less than 0.05 for any
 

comparison.
 

(f) The 95% confidence interval of the relative risk between each dosed group and the specified
 

control group.
 
APPENDIX G
 

ANALYSIS OF FORMULATED DIETS FOR
 

CONCENTRATIONS OF PARATHION
 

99
 
100

 
APPENDIX G
 

Analysis of Formulated Diets for
 

Concentrations of Parathion
 

A 10-g sample of the formulated diet was shaken with 125 ml
 

hexane for 16 hours at ambient temperature. The mixture was then
 

filtered through Celite with hexane washes, and the combined
 

filtrates were reduced in volume to 10 ml. After appropriate
 

dilutions, the solution was analyzed quantitatively for parathion
 

by gas-liquid chromatography (electron capture detector, 5% QF-1
 

on Chromosorb W column). Recoveries were determined with spiked
 

samples, and external standards were used for calibration.
 

Theoretical No. of Sample Coefficient of Range (ppm) 

Concentrations Samples nalytical Variation (%) 

in Diet (ppm) ean (ppm) 

20 16 20.1 5.9% 17.2-21.6 

30 11 29.7 4.7% 27.1-32.0 

40 14 39.2 3.6% 37.5-41.8 

60 10 59.0 6.5% 55.2-65.1 

80 21 79.6 5.1% 75.0-89.0 

160 14 160.8 4.5% 150.0-171.0 

101
 
102

 
Review of the Bioassay of Parathion* for Carcinogenicity
 

by the Data Evaluation/Risk Assessment Subgroup of the
 

Clearinghouse on Environmental Carcinogens
 

August 31, 1978
 

The Clearinghouse on Environmental Carcinogens was established in
 

May, 1976, in compliance with DREW 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 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
 

Parathion for carcinogenicity.
 

A toxicologist with Monsanto Company presented a public statement
 

regarding the bioassay of Parathion. He noted that Monsanto is the
 

major producer of Parathion, an agent used for the control of insects
 

and mites on food and fiber crops. He said that Parathion does not
 

pose an undue hazard if used in accordance with prescribed precautions.
 

He made the following points: 1) the high spontaneous incidence of
 

adrenal cortical tumors in the Osborne-Mendel rat should be given due
 

consideration in evaluating the significance of this tumor type among
 

treated animals; 2) pathological examination of treated rats failed to
 

detect non-tumorigenic adrenal lesions which would indicate an insult
 

to the organ; and 3) results from the NCI bioassay are inconsistent
 

with those from three other reported studies, indicating no treatment-


related histological changes in animals fed Parathion. He urged that
 

the overall conclusion in the report reiterate the statement from the
 

pathology section that "Paration did not appear to be carcinogenic in
 

Osborne-Mendel rats under the conditions of this bioassay."
 

103
 
The primary reviewer said that the report noted an elevated
 

incidence of adrenal tumors in treated rats. No treatment-related
 

tumors were observed in mice. Although the study was marred by the use
 

of a small number of matched control animals, the deficiency was compensated for by using pooled controls in the statistical analysis of the
 

study. He pointed out that the toxicity of Parathion inhibited the
 

levels of the compound that could be administered. He further stated
 

that the increased incidence of adrenal neoplasms in treated rats should
 

not be taken as conclusive evidence for the carcinogenicity of Parathion.
 

The primary reviewer recommended that consideration be given to a retest
 

of the compound, possibly in a different species. He added that it
 

would be premature to assess the possible human risk posed by Parathion.
 

The secondary reviewer indicated that the evidence was insufficient
 

to conclude that Parathion was carcinogenic in treated rats or mice,
 

under the conditions of test. He suggested that the conclusion in the
 

report be reworded as follows: "There were more adrenal cortical
 

adenomas and carcinomas among the treated rats than among pooled and
 

historical controls, suggesting a carcinogenic effect that requires
 

further study." He opined that the increase in adrenal neoplasms may
 

have been associated with the stress of the animals. Although he agreed
 

with the shortcomings noted by the primary reviewer, he still considered
 

the study valid for the purpose for which it was undertaken. Based on
 

the results of the study, he concluded that Parathion did not pose a
 

carcinogenic risk to man.
 

A motion was approved unanimously that the report on the bioassay of
 

Parathion be accepted as written.
 

Members present were:
 

Arnold Brown (Chairman), University of Wisconsin School of Medicine
 

Joseph Highland, Environmental Defense Fund
 

Michael 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.
 

J>U.b. GOVERNMEN T PRINTIN G OFFICE . I 978-?81'2 17/327 I
 

104
 

DHEW Publication No. (NIH) 79-1320