United States
kS^laMIjk Environmental Protection
^J^iniiil m11 Agency
EPA/690/R-10/003F
Final
9-30-2010
Provisional Peer-Reviewed Toxicity Values for
4-Chloro-2-methylaniline
(CASRN 95-69-2)
Superfund Health Risk Technical Support Center
National Center for Environmental Assessment
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, OH 45268

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TABLE OF CONTENTS
COMMONLY USED ABBREVIATIONS	ii
BACKGROUND	1
HISTORY	1
DISCLAIMERS	1
QUESTIONS REGARDING PPRTVS	2
INTRODUCTION	2
REVIEW OF POTENTIALLY RELEVANT DATA (CANCER AND NONCANCER)	4
HUMAN STUDIES	8
Oral Exposures	8
Inhalation Exposures	8
Other Exposures	8
ANIMAL STUDIES	9
Oral Exposures	9
Short-term Studies	9
Subchronic-duration Studies	9
Chronic-Duration Studies	10
Developmental and Reproduction Studies	16
Inhalation Exposures	16
Short-term Studies	16
Sub chronic-Duration Studies	16
Chronic-Duration Studies	16
Developmental and Reproductive Studies	16
Other Exposures	16
OTHER DATA (SHORT-TERM TESTS, OTHER EXAMINATIONS)	16
DERIVATION 01 PROVISIONAL VALUES	22
DERIVATION 01 ORAL REFERENCE DOSES	22
Derivation of Subchronic Provisional RfD	22
Derivation of Chronic Provisional RfD	27
DERIVATION OF INHALATION REFERENCE CONCENTRATIONS	27
Derivation of Subchronic Provisional RfC	27
Derivation of Chronic Provisional RfC	27
CANCER WEIGHT-OF-EVIDENCE DESCRIPTOR	27
MODE-OF-ACTION DISCI SSION	29
Mutagenic Mode of Action	29
Key Events	29
Strength, Consistency, Specificity of Association	29
Dose-Response Concordance	29
Temporal Relationships	29
Biological Plausibility and Coherence	30
Conclusions	30
DERIVATION OF PROVISIONAL CANCER POTENCY VALUES	30
Derivation of Provisional Oral Slope Factor	30
Derivation of Provisional Inhalation Unit Risk	32
APPENDIX A. PROVISIONAL SCREENING VALUES	33
APPENDIX B. DATA TABLES	35
APPENDIX C. BMD MODELING OUTPUTS FOR 4-CHLORO-2-METHYANILINE	43
APPENDIX D. REFERENCES	64
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COMMONLY USED ABBREVIATIONS
BMC
Benchmark Concentration
BMD
Benchmark Dose
BMCL
Benchmark Concentration Lower bound 95% confidence interval
BMDL
Benchmark Dose Lower bound 95% confidence interval
HEC
Human Equivalent Concentration
HED
Human Equivalent Dose
IRIS
Integrated Risk Information System
IUR
inhalation unit risk
LOAEL
lowest-observed-adverse-effect level
LOAELadj
LOAEL adjusted to continuous exposure duration
LOAELhec
LOAEL adjusted for dosimetric differences across species to a human
NOAEL
no-ob served-adverse-effect level
NOAELadj
NOAEL adjusted to continuous exposure duration
NOAELhec
NOAEL adjusted for dosimetric differences across species to a human
NOEL
no-ob served-effect level
OSF
oral slope factor
p-IUR
provisional inhalation unit risk
p-OSF
provisional oral slope factor
p-RfC
provisional reference concentration (inhalation)
p-RfD
provisional reference dose (oral)
POD
point of departure (oral)
RfC
reference concentration (inhalation)
RfD
reference dose
UF
uncertainty factor
UFa
animal-to-human uncertainty factor
UFC
composite uncertainty factor
UFd
incomplete-to-complete database uncertainty factor
UFh
interhuman uncertainty factor
UFl
LOAEL-to-NOAEL uncertainty factor
UFS
subchronic-to-chronic uncertainty factor
WOE
weight of evidence
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PROVISIONAL PEER-REVIEWED TOXICITY VALUES FOR
4 (111 ORO-2MI THYI AMI JNE (CASRN 95-69-2)
BACKGROUND
HISTORY
On December 5, 2003, the U.S. Environmental Protection Agency's (EPA) Office of
Superfund Remediation and Technology Innovation (OSRTI) revised its hierarchy of human
health toxicity values for Superfund risk assessments, establishing the following three tiers as the
new hierarchy:
1)	EPA's Integrated Risk Information System (IRIS).
2)	Provisional Peer-Reviewed Toxicity Values (PPRTVs) used in EPA's Superfund
Program.
3)	Other (peer-reviewed) toxicity values, including
~	Minimal Risk Levels produced by the Agency for Toxic Substances and Disease
Registry (ATSDR),
~	California Environmental Protection Agency (CalEPA) values, and
~	EPA Health Effects Assessment Summary Table (HEAST) values.
A PPRTV is defined as a toxicity value derived for use in the Superfund Program when
such a value is not available in EPA's IRIS. PPRTVs are developed according to a Standard
Operating Procedure (SOP) and are derived after a review of the relevant scientific literature
using the same methods, sources of data, and Agency guidance for value derivation generally
used by the EPA IRIS Program. All provisional toxicity values receive internal review by a
panel of six EPA scientists and external peer review by three independently selected scientific
experts. PPRTVs differ from IRIS values in that PPRTVs do not receive the multiprogram
consensus review provided for IRIS values. This is because IRIS values are generally intended
to be used in all EPA programs, while PPRTVs are developed specifically for the Superfund
Program.
Because new information becomes available and scientific methods improve over time,
PPRTVs are reviewed on a 5-year basis and updated into the active database. Once an IRIS
value for a specific chemical becomes available for Agency review, the analogous PPRTV for
that same chemical is retired. It should also be noted that some PPRTV documents conclude that
a PPRTV cannot be derived based on inadequate data.
DISCLAIMERS
Users of this document should first check to see if any IRIS values exist for the chemical
of concern before proceeding to use a PPRTV. If no IRIS value is available, staff in the regional
Superfund and Resource Conservation and Recovery Act (RCRA) program offices are advised to
carefully review the information provided in this document to ensure that the PPRTVs used are
appropriate for the types of exposures and circumstances at the Superfund site or RCRA facility
in question. PPRTVs are periodically updated; therefore, users should ensure that the values
contained in the PPRTV are current at the time of use.
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It is important to remember that a provisional value alone tells very little about the
adverse effects of a chemical or the quality of evidence on which the value is based. Therefore,
users are strongly encouraged to read the entire PPRTV document and understand the strengths
and limitations of the derived provisional values. PPRTVs are developed by the EPA Office of
Research and Development's National Center for Environmental Assessment, Superfund Health
Risk Technical Support Center for OSRTI. Other EPA programs or external parties who may
choose of their own initiative to use these PPRTVs are advised that Superfund resources will not
generally be used to respond to challenges of PPRTVs used in a context outside of the Superfund
Program.
QUESTIONS REGARDING PPRTVS
Questions regarding the contents of the PPRTVs and their appropriate use (e.g., on
chemicals not covered, or whether chemicals have pending IRIS toxicity values) may be directed
to the EPA Office of Research and Development's National Center for Environmental
Assessment, Superfund Health Risk Technical Support Center (513-569-7300), or OSRTI.
4-Chloro-2-methylaniline (also referred to as 4-chloro-o-toluidine) and its hydrochloride
salt can serve as a component in various dyes and pigments—including azo dyes used for
coloring fabrics—and was used from the 1960s though the 1980s in the production of
chlordimeform, an acaricide and insecticide (IARC, 1990). The empirical formula for
4-chloro-2-methylaniline is CyHgCIN (see Figure 1). A table of chemico-physical properties is
provided below (see Table 1). In this document, unless otherwise noted, "statistically
significant" denotes ap-value < 0.05.
INTRODUCTION
NH-
CI
Figure 1. 4-Chloro-2-Methylaniline Structure
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Table 1. Physical Properties Table (4-Chloro-2-Methylaniline)a
Property (unit)
Value
Boiling point (°C)
241
Melting point (°C)
29-30
Density (g/cm3)
1.19
Vapor pressure (Pa at 25 °C)
5.5 mmHg
pH (unitless)
Not available
Solubility in water (g/100 mL at 25 °C)
0.095
Relative vapor density (air =1)
4.9
Molecular weight (g/mol)
141.6
Flash point (°C)
99
Octanol/water partition coefficient (unitless)
2.27 (Log Kow)
aNational Institute for Occupational Safety and Health (NIOSH, 2003).
The U.S. Environmental Protection Agency (U.S. EPA) IRIS database (U.S. EPA, 2009)
does not list a chronic oral reference dose (RfD), a chronic inhalation reference concentration
(RfC), or a cancer assessment for 4-chloro-2-methylaniline. Subchronic or chronic RfDs or
RfCs for 4-chloro-2-methylaniline are not listed in the HEAST (U.S. EPA, 2003) or the Drinking
Water Standards and Health Advisories list (U.S. EPA, 2006). The HEAST (U.S. EPA, 2003)
reports a cancer weight-of evidence (WOE) classification of Group B2 (Probable Human
Carcinogen) and oral slope factors (OSFs) of 5.8 x 10 1 mg/kg-day 4-chloro-2-methylaniline and
4.6 x 10 1 mg/kg-day 4-chloro-2-methylaniline hydrochloride, with corresponding unit risk
factors of 1.6 x io~5 |^g/L and 1.3 x 10~5 (^g/L, respectively, based on increased incidence of
vascular tumors in male and female mice treated with 4-chloro-2-methylaniline hydrochloride
(Weisburger et al., 1978). Due to use of the salt form in this study, the OSF of
4.6 x 10 1 mg/kg-day from treatment with 4-chloro-2-methylaniline hydrochloride was converted
to the free-base OSF by multiplying the molecular weight ratio of the salt to the base to get
5.8 x 10_1 mg/kg-day. The 1994 CARA list (U.S. EPA, 1994a) includes a Health and
Environmental Effects Profile (HEEP) for 4-chloro-2-methylaniline, detailing a Reportable
Quantity (RQ) value of 5000 for both 4-chloro-2-methylaniline and 4-chloro-2-methylaniline
hydrochloride, as well as carcinogen potency factors for oral exposure of 0.58 mg/kg-day and
0.46 mg/kg-day, respectively. No occupational exposure limits for 4-chloro-2-methylaniline
have been derived by the American Conference of Governmental Industrial Hygienists (ACGIH,
2009), the National Institute of Occupational Safety and Health (NIOSH, 2003), or the
Occupational Safety and Health Administration (OSHA, 1998). The toxicity of
4-chloro-2-methylaniline has not been reviewed by the ATSDR (2008) or the World Health
Organization (WHO, 2010). The International Agency for Research on Cancer (IARC, 2000)
has published a toxicological review on 4-chloro-2-methylaniline, and the National Toxicology
Program (NTP, 2005) management status and health and safety reports for
4-chloro-2-methylaniline were consulted for relevant information.
Literature searches were conducted on sources published from 1900 through
August 2010, for studies relevant to the derivation of provisional toxicity values for
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4-chloro-2-methylaniline, CAS No. 95-69-2. Searches were conducted using EPA's Health and
Environmental Research Online (HERO) evergreen database of scientific literature. HERO
searches the following databases: AGRICOLA; American Chemical Society; BioOne; Cochrane
Library; DOE: Energy Information Administration, Information Bridge, and Energy Citations
Database; EBSCO: Academic Search Complete; GeoRef Preview; GPO: Government Printing
Office; Informaworld; IngentaConnect; J-STAGE: Japan Science & Technology; JSTOR:
Mathematics & Statistics and Life Sciences; NSCEP/NEPIS (EPA publications available through
the National Service Center for Environmental Publications [NSCEP] and National
Environmental Publications Internet Site [NEPIS] database); PubMed: MEDLINE and
CANCERLIT databases; SAGE; Science Direct; Scirus; Scitopia; SpringerLink; TOXNET
(Toxicology Data Network): ANEUPL, CCRIS, ChemlDplus, CIS, CRISP, DART, EMIC,
EPIDEM, ETICBACK, FEDRIP, GENE-TOX, HAPAB, HEEP, HMTC, HSDB, IRIS, ITER,
LactMed, Multi-Database Search, NIOSH, NTIS, PESTAB, PPBIB, RISKLINE, TRI, and
TSCATS; Virtual Health Library; Web of Science (searches Current Content database among
others); World Health Organization; and Worldwide Science. The following databases outside
of HERO were searched for risk assessment values: ACGIH, ATSDR, CalEPA, EPA IRIS, EPA
HEAST, EPA HEEP, EPA OW, EPA TSCATS/TSCATS2, NIOSH, NTP, OSHA, and RTECS.
REVIEW OF POTENTIALLY RELEVANT DATA
(CANCER AND NONCANCER)
Table 2 provides information for all of the potentially relevant toxicity studies. Entries
for the principal studies are bolded.
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Table 2. Summary of Potentially Relevant Data for 4-Chloro-2-Methylaniline (CASRN 95-69-2)
Category
Number Male/Female,
Species, Study Type, Study
Duration
Dosimetry"
Effects Observed
NOAEL"
BMDL/
BMCLa
LOAELab
Reference
(Comments)
Notes0
Human
1. Oral (mg/kg-day)a
None
2. Inhalation (mg/m3)a
Subchronic
None
Chronic
None
Developmental
None
Reproductive
None
Carcinogenic
116/0, occupational, median
exposure duration =
25.5 years
Not reported
Bladder cancer.
None
Not run
None
(Stasik, 1988)

49/0, occupational, duration
of exposure ranged from 3 to
956 days
Not reported
Bladder cancer.
None
Not run
None
(Popp et al., 1992)

342 employees (sex not
reported), occupational,
exposure duration reported as
1 to 5+ years
Not reported
Malignant neoplasms causing
death.
None
Not run
None
(Ott and Langner,
1983)

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Table 2. Summary of Potentially Relevant Data for 4-Chloro-2-Methylaniline (CASRN 95-69-2)
Category
Number Male/Female,
Species, Study Type, Study
Duration
Dosimetry"
Effects Observed
NOAEL"
BMDL/
BMCLa
LOAELab
Reference
(Comments)
Notes0
Animal
1. Oral (mg/kg-day)a
Subchronic
5/5, F344 rat, diet, 7 d/wk,
for 7 wks
Male ADJ: 25,50,
100,200, 400,600,
620,650, 700, 800,
1000
Female ADJ: 113,
282,339, 452, 677,
700, 734, 790, 903,
1130,1410,2820,
5650
10% decrease in mean body
weight in females.
677
Not run
700
(NCI, 1979)
PS

5/5, B6C3F1 mouse, diet,
7 d/wk for 7 wks
Male ADJ: 361,
722, 902, 1350,
1800, 2710
Female ADJ:
2930, 3410, 3900
10% decrease in mean body weight
in males and females.
1800
Not run
2710
(NCI, 1979)

Chronic
30/30, Sprague-Dawley rat,
diet, 7 d/wk for 94 and
104 wks for males and
females, respectively
Male ADJ: 1.38,
6.88, 34.4
Female ADJ: 1.64,
8.20,41.0
Increased liver weights in males
and females.
8.20
Not run
34.4
(Ciba-Geigy,
1992a)
NPR

30/30, ICR mouse, diet,
7 d/wk for 80 wks
Male ADJ: 3.60,
18.0, 89.9
Female ADJ:
3.69,18.4, 92.2
Decreased total serum protein in
males and females; increased
blood urea nitrogen (BUN) in
females; increased serum
glutamic pyruvic transaminase
(SGPT) in females; mortality in
males and females.
3.69
Not run
18.0 (FEL)
(Ciba-Geigy,
1992b)
PS,
NPR
Developmental
None
Reproductive
125/0, NMRI/SPF mouse,
gavage, 7 d/wk for 7 wks
Male ADJ: 200
Reproductive performance in the
F0 and F1 males.
200
Not run
None
(Lang and Adler,
1982)

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Table 2. Summary of Potentially Relevant Data for 4-Chloro-2-Methylaniline (CASRN 95-69-2)
Category
Number Male/Female,
Species, Study Type, Study
Duration
Dosimetry"
Effects Observed
NOAEL3
BMDL/
BMCLa
LOAELab
Reference
(Comments)
Notes0
Carcinogenic
50/50, F344 rat, diet, 7 d/wk
for 107 wks
Male HED: 26.8,
107
Female HED:
27.4, 110
Increased adenomas of the
pituitary in males and females.
26.8
No fit
107
(NCI, 1979)


25/0, CD rat, diet, 7 d/wk for
18 mos
Male HED: 35.4,
70.8
No effects observed.
70.8
Not run
None
(Weisburger et al.,
1978)


30/30, Sprague-Dawley rat,
diet, 7 d/wk, 94 and 104 wks
for males and females,
respectively
Male HED: 0.405,
2.02, 10.1
Female HED:
0.421,2.11, 10.5
Increased liver tumors (benign and
malignant) in males and females.
None
Not run
0.405
(Ciba-Geigy,
1992a)
NPR

50/50, B6C3F1 mice, diet,
7 d/wk for 92-99 wks
Male HED: 98.4,
393
Female HED:
32.8, 131
Increased hemangiomas and
hemangiosarcomas in males and
females.
None
50.87 for
males
only
32.8
(NCI, 1979)


25/25, HaM/ICR mouse,
diet, 7 d/wk for 18 mos
Male HED: 19.7,
39.4
Female HED:
52.5,105
Increased vascular tumors
(hemangiomas and
hemangiosarcomas) and total
tumors in males and females.
None
2.24 for
males
only
19.7
(Weisburger et
al., 1978)
PS

30/30, ICR mouse, diet,
7 d/wk for 80 wks
Male HED: 0.525,
2.62, 13.1
Femal HED:
0.525,2.62, 13.1
Increased reticulum cell sarcomas
and unclassified malignant tumors.
None
Not run
0.525
(Ciba-Geigy,
1992b)
NPR
2. Inhalation (mg/m3)a
None
""Dosimetry, NOAEL, BMDL/BMCL, and LOAEL values are converted to Human Equivalent Dose (HED in mg/kg-day) or Human Equivalent Concentration (HEC
in mg/m3) units. Noncancer oral data are only adjusted for continuous exposure.
bNot reported by the study author but determined from the data.
°Notes: IRIS = Utilized by IRIS, date of last update; PS = Principal study, NPR = Not peer reviewed.
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HUMAN STUDIES
Oral Exposures
No studies investigating the effects of subchronic or chronic oral exposure to
4-chloro-2-methylaniline in humans have been identified.
Inhalation Exposures
No studies investigating the effects of subchronic or chronic inhalation exposure to
4-chloro-2-methylaniline in humans have been identified.
Other Exposures
Little information is available regarding occupational exposure of humans to
4-chloro-2-methylaniline, although three retrospective studies analyzing outcomes of workers
exposed during manufacturing are presented below.
Stasik (1988) reported that 116 male workers in a 4-chloro-2-methylaniline production
and processing plant (Hoechst AG; Frankfurt, Germany), employed before protective industrial
hygiene improvements were made to the plant in 1970, had a significantly higher incidence of
bladder cancer. The exposure of this historical subcohort was presumed to be high, although no
measurements of exposure were available. Within this subcohort of 116 workers, 8 individuals
developed carcinomas of the urinary bladder. The median exposure duration pre-1970 for the
eight individuals with bladder cancers was 14 years, while the median total exposure (pre- and
post-1970) was 25.5 years. The authors used sex- and age-specific population data from the
nearby German state of Saarland for 1983 to calculate the expected incidence rate of bladder
cancer among the subcohort. The expected incidence was calculated to be 0.11 among the
116 workers. When compared to the actual incidence rate, the authors reported a standardized
incidence rate that was 72.7 times higher than expected for bladder cancer in a comparable
population. Confounders such as smoking and exposure to other contaminants are not taken into
account in this study, and the sample size limits the statistical power of the study.
Similarly, Popp et al. (1992) described seven cases of bladder cancer among 49 male
workers involved in the synthesis of chlordimeform from 4-chloro-2-methylaniline in Germany.
The study authors reported that exposure duration ranged from three to 956 days, and for n = 39
workers, an average of 18 years had passed since the start of exposure by the end of 1990;
however, the typical production period was 8-12 weeks per year. No exposure measurements
were taken. Using similar statistical analysis to Stasik (1988), the incidence rate of bladder
tumors in the cohort was compared to the standard incidence rates of populations from the
former German Democratic Republic (1978 to 1982), Saarland (1988), and Denmark (1978 to
1982). The incidence rate of bladder cancer with the cohort was calculated to be 89.7, 53.8, and
35.0 times higher than the comparable populations in the former German Democratic Republic,
Saarland, and Denmark, respectively.
A retrospective cohort of 342 employees (sex not reported) in a plant in the United States
from 1914 and 1958, engaged in the production of dyes that involved the use and
uncharacterized exposure to 4-chloro-2-methylaniline, was studied by Ott and Langner (1983)
for increased mortality or cancer incidence that would have been reported in U.S. census data as
a cause of death. After removing groups of employees for separate analysis due to confounding
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factors, 275 individuals were found to have a standard mortality ratio from total malignant
neoplasms of 1.3 and a standard mortality ratio of 1.8 from malignant neoplasms in the digestive
tract.
While these studies provide important data that taken together support the possibility of
increased cancers from exposure to 4-chloro-2-methylaniline, they are limited by the small
populations analyzed, as well as the scope of outcomes and analyses available. Furthermore, no
measurement or estimation of dose, form, or route of exposure was made. Coexposure to other
potential carcinogens in the workplace (e.g., aromatic amines) and lack of controlling for tobacco
usage also confounds the interpretation of the human data. Thus, these studies do not support the
derivation of a provisional toxicity value.
ANIMAL STUDIES
Oral Exposures
The effects of oral exposure of animals to 4-chloro-2-methylaniline have been evaluated
in subchronic-duration (NCI, 1979), chronic-duration (NCI, 1979; Weisburger et al., 1978;
Ciba-Geigy, 1992a,b), and reproductive studies (Lang and Adler, 1982). NCI (1979) is a report
of the bioassay for possible carcinogenicity, which includes four studies. To make the
differentiation between the studies, a designation using the study type and species will be made
(i.e., subchronic-duration mouse study) for each of the four studies, and the reference, NCI
(1979), will be used throughout this document. Similarly, Weisburger et al. (1978) is an article
that reports results from two chronic-duration studies. To make the differentiation between the
studies, they will be designated using the species (i.e., rats or mice), but the reference for the
entire Weisburger et al. (1978) study will be used in all cases. Ciba-Geigy sponsored two
chronic-duration toxicity studies in 1992, which will be referred two as Ciba-Geigy (1992b) and
Ciba-Geigy (1992a) to differentiate. Lang and Adler (1982) conducted a reproduction study
using oral exposure in male mice. No studies investigating the developmental toxicity of
4-chloro-2-methylaniline have been identified.
Short-term Studies—No studies could be located regarding the effects of short-term oral
exposure to 4-chloro-2-methylaniline.
Subchronic-duration Studies—The study by NCI (1979) is selected as the principal
study for deriving the subchronic p-RfD. NCI (1979) reported an 8-week study in which groups
of five F344 male rats were administered 4-chloro-2-methylaniline hydrochloride (purity >99%,
based on liquid chromatography analysis) at 0, 250, 500, 1000, 2000, or 4000 ppm (0, 25, 50,
100, 200, or 400 mg/kg-day average daily dose) in the diet in one test or 6000, 6200, 6500, 7000,
8000, or 10,000 ppm (600, 620, 650, 700, 800, or 1000 mg/kg-day average daily dose) in the diet
in a separate test (see Appendix B, Table B. 1). In the same study, five F344 female rats were
also administered 4-chloro-2-methylaniline at 0, 1000, 2500, 3000, or 4000 ppm (0, 113, 282,
339, or 452 mg/kg-day average daily dose); 0, 6000, 6200, 6500, 7000, 8000, or 10,000 ppm (0,
677, 700, 734, 790, 903, or 1130 mg/kg-day average daily dose); and 0, 6200, 12,500, 25,000 or
50,000 ppm (0, 700, 1410, 2820, or 5650 mg/kg-day average daily dose) in the diet of 4-chloro-
2-methylaniline in three separate tests as shown in Table B. 1. All animals were treated 7 days
per week, for 7 weeks followed, by 1 week of observation after which all animals were
sacrificed. The study authors recorded body weights before treatment, then biweekly during the
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exposure period, and before termination, along with clinical observations. The study authors
necropsied the rats at 8 weeks and conducted histopathological examinations.
A decrease in mean body weights when compared to controls was seen as doses
increased, but female rats showed less of a dose-response relationship than males (see
Table B.l). In the first and second experiments in male and female rats, there was a
dose-response relationship between decrease in body weight and increasing doses of
4-chloro-2-methylaniline (see Table B.l). In the third experiment in female rats, the
dose-response relationship between decrease in body weights and increasing doses of
4-chloro-2-methylaniline was more evident and noticeable (see Table B.l), with all treated
animals exhibiting a greater than 10% decrease in body weight compared to the concurrent
controls. In addition to decreases in body weight, an enlargement of the spleen was observed in
the 1000- and 1130-mg/kg-day dose groups in males and females, respectively, as well as in
males in the 650-mg/kg-day dose group (data not provided by study authors). This effect was
reported to be produced by increased hematopoiesis and hyperemia (no data presented by study
authors). Increases in marrow cellularity involving all cell types were also noted, although no
data or statistics on the histopathology are provided in the report. No other treatment-related
effects were seen during the clinical and histopathologic examinations. All female rats in the
third experiment in the 5650-mg/kg-day dose group died during the exposure period, but the
cause of death was not examined. Based on a 10% decrease in body weight in females from the
third experiment (see Table B. 1), a LOAELadj of 700 mg/kg-day is identified, and a NOAELadj
of 677 mg/kg-day from the first experiment in female rats (see Table B.l) is identified (NCI,
1979).
In a study parallel to the sub chronic-duration rat study described above, a
sub chronic-duration mouse study was conducted by NCI (1979). Groups of five B6C3F1 male
mice were administered 0, 2000, 4000, 5000, 7500, 10,000, or 15,000 ppm of 4-chloro-
2-methylaniline hydrochloride, and five B6C3F1 female mice were administered 0, 15,000,
17,500, or 20,000 ppm in the diet 7 days per week for 7 weeks. The corresponding adjusted
daily doses are 0, 361, 722, 902, 1350, 1800, or 2710 mg/kg-day and 0, 2930, 3410, or
3900 mg/kg-day 4-chloro-2-methylaniline in the diet, for males and females, respectively. After
7 weeks of treatment and 1 week of observation, the study authors sacrificed all animals.
Animals were evaluated in the same manner as the 7-week NCI (1979) subchronic-duration rat
study.
Oral treatment of mice with 4-chloro-2-methylaniline in the diet did not affect the
survival of any group. Similar to the NCI (1979) subchronic-duration rat study, calculated mean
body weights on Day 49 decreased with increasing doses in both sexes (see Table B.2). The
2710- and 2930-mg/kg-day dose groups of male and female mice, respectively, showed a
10%) body weight decrease relative to control. No other treatment-related effects were seen
during the clinical and histopathologic examinations. Based on a 10%> body weight decrease
observed in males, a LOAELadj of 2710 mg/kg-day and a NOAELadj of 1800 mg/kg-day are
identified for 4-chloro-2-methylaniline.
Chronic-Duration Studies—The study by Ciba-Geigy (1992b) is selected as the
principal study for deriving the chronic p-RfD. The effects of chronic oral exposure to 4-chloro-
2-methylaniline have been investigated in an 80-week study in ICR mice (Ciba-Geigy, 1992b).
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Ciba-Geigy (1992b), in an unpublished study, treated groups of 30 ICR mice per sex per dose
group with neat 4-chloro-2-methylaniline hydrochloride (purity not reported) in the diet at doses
of 0, 20, 100, or 500 ppm daily for 80 weeks. The corresponding adjusted daily doses were 0,
3.60, 18.0, or 89.9 mg/kg-day in the male mice and 0, 3.69, 18.4, or 92.2 mg/kg-day in the
female mice. For the cancer endpoints, the corresponding HEDs are 0, 0.525, 2.62, or
13.1 mg/kg-day for male and female mice. The study authors observed mice for mortality and
clinical signs of toxicity at unreported intervals and monitored body weight and food
consumption of the mice weekly. Urinalysis (pH, glucose, albumen, acetone, occult blood,
urobilinogen, and bile pigments) and hematological examinations (hemoglobin, erythrocyte
count, leukocyte count, and differential leukocyte count) were conducted on all mice prior to
treatment and after 55 and 80 weeks of treatment. Bone marrow (differential bone marrow cell
count), serum chemistry (total protein, urea nitrogen, glucose, glutamic oxaloacetic
transaminase, glutamic pyruvic transaminase, alkaline phosphatase, and total cholesterol), tissue
pathology (bone marrow, peripheral nerve, brain, small intestines, eyes, heart, testes, pituitary,
lungs, ovaries, thyroid gland, spleen, adrenal glands, thymus, liver, lymph nodes, kidneys,
pancreas, urinary bladder, stomach, and tumors), as well as the blood thrombocyte count were
evaluated in all mice at 80 weeks. Macroscopic pathology and organ weights of the brain, heart,
lung, liver, kidney, adrenal gland, pituitary gland, thyroid, thymus, testis, ovary, and eye after
termination of exposure at 80 weeks were also analyzed.
Although the study authors did not report the statistical significance of the endpoints
examined, independent significance tests were performed for this review and are presented in
Table B.3 (statistically significantly different from control at/? < 0.05). Treatment resulted in
dose-related increased mortality in treated females, and to a lesser extent, treated males, with the
female high-dose group showing 100% mortality by Week 67 (Ciba-Geigy, 1992b). Mortality
was significantly increased in males and females at the mid- and high-dose groups (Fisher's
Exact Test, p < 0.05). The weekly mean body weights for 4-chloro-2-methylaniline-treated
animals sacrificed at the end of the study were similar to controls throughout the study, with the
exception of the high-dose females, which reportedly had slightly depressed body weights (data
not shown by study authors). Food intake did not vary according to exposure.
The study authors reported no marked treatment-related effects on any urinalysis
parameters or hematological parameters in mice sacrificed at study termination. The only
significant effect observed in the urinalysis is the urine pH in females exposed to
18.4 mg/kg-day. Relative organ weights exhibited a significant difference-with kidneys showing
a decrease in males exposed in the 18.0-mg/kg-day dose group, thyroid gland (increase) in males
exposed to 3.60 mg/kg-day, and spleen (increase) in females exposed to 18.4 mg/kg-day.
Significant changes in the hematological values are decreases at all doses in thrombocyte cell
counts in males, decreases in lymphocytes in all doses in males, an increase in neutrophils in
males exposed to 3.60 mg/kg-day, increases in the white blood cell count in high-dose females,
increases in neutrophils in the females exposed to 3.69 mg/kg-day, and decreases in lymphocytes
in females exposed to 3.69 mg/kg-day. Bone marrow analysis indicated reduced erythroblast
counts in male mice treated with 3.60 mg/kg-day of 4-chloro-2-methylaniline compared to the
control group; however, the counts were normal in male mice treated with 18.0 and
89.9 mg/kg-day 4-chloro-2-methylaniline.
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Table B.3 summarizes the changes in biochemical parameters in the
4-chloro-2-methylaniline exposure groups after 80 weeks of exposure. Decreases in total serum
protein are found to be significant in the 3.60-mg/kg-day dose group for the males and in the
3.69- and 18.4-mg/kg-day dose groups in the sacrificed females; however, the biological
relevance of this finding in and of itself is questionable. Other significant increases over control
values included glucose in the males of the 3.60-mg/kg-day dose group, serum glutamic pyruvic
transaminase (SGPT) in the females of the 18.4-mg/kg-day dose group, and BUN in the females
of the 3.69-mg/kg-day dose group.
Table B.4 presents the percentage of specific tumor incidences in the exposed mice.
Increases in hepatoma (probably benign), leukemia (includes lymphosarcomas), lung-adenomas,
reticulum cell sarcomas, probably reticulum cell sarcomas, fibrosarcoma, and probably
fibrosarcoma along with other benign and unclassified malignant tumors were reported using the
Naive method. The authors reported that there were no additional dose-related findings
regarding macroscopic or histopathological analysis of any organs.
Based on the absence of biologically significant findings and significant frank effects
(i.e., mortality) in mice at 3.69 mg/kg-day, this dose is identified as a NOAELadj for
4-chloro-2-methylaniline. A frank effect level (FELadj) of 18.0 mg/kg-day is also identified.
Though useful in derivation of a p-RfD, this study was not selected as the primary study for
deriving a p-OSF because other peer-reviewed studies of equal or greater scientific merit were
available.
In another unpublished chronic-duration study (94 weeks and 104 weeks, for males and
females, respectively) conducted by Ciba-Geigy (1992a), groups of 30 Sprague-Dawley rats per
sex per dose group were administered 0, 20, 100, or 500 ppm of 4-chloro-2-methylaniline
hydrochloride (purity not specified) by diet. The corresponding adjusted daily doses were 0,
1.38, 6.88, or 34.4 mg/kg-day for the male rats and 0, 1.64, 8.20, or 41.0 mg/kg-day for female
rats. The corresponding HEDs were 0, 0.405, 2.02, or 10.1 mg/kg-day for the male rats and 0,
0.421, 2.11, or 10.5 mg/kg-day for female rats. The study authors performed macroscopic
pathology and organ weight analysis (brain, heart, lungs, liver, kidneys, adrenal glands, thyroid
gland, pituitary gland, thymus, testes, ovaries, and eyes) following sacrifice. Tissues were
preserved and stained for histopathology, (bone marrow, peripheral nerve, brain, heart, lungs,
spleen, liver, kidneys, pancreas, small intestine, testes, ovaries, adrenal glands, lymph nodes,
urinary bladder, eyes, pituitary gland, thyroid gland, thymus, stomach, and any tumors) and
microscopic examination was conducted on the same tissues of all animals following the
termination of the exposure duration.
Although the study authors did not report the statistical significance of the endpoints
examined, independent significance tests are performed for this review (statistically different
from control at/? < 0.05). The 1.38-and 6.88-mg/kg-day dose groups in male rats are
significantly different from the control in the heart, lung, adrenal, and brain weights. However,
these organ weight increases did not appear to be dose related as none of them were significantly
increased at the high-dose (34.4 mg/kg-day) level. The liver was the only organ whose weight
was significantly increased over the control group at the 34.4-mg/kg-day dose in male rats. The
only significant change in organ weights of female rats treated with 4-chloro-2-methylaniline
was noted in liver, which showed an increase in weight in the 41.0-mg/kg-day dose group when
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compared to the control group. Gross macroscopic findings included a significantly increased
incidence of "tumor-like nodules" of the liver in the 34.4-mg/kg-day dose males, as well as the
8.2 and 41.0-mg/kg-day dose females. However, the biological significance of these "tumor-like
nodules" is unclear because they are not well characterized pathologically, and it is also
unknown whether they could be preneoplastic in nature. Therefore, it is not prudent to use this
endpoint quantitatively in the derivation of a chronic p-RfD. Although significant changes in
heart, lung, adrenal, and brain weights were seen in males at the lowest dose tested, these
changes were not dose-related. Thus, based on increased liver weight observed in both males
and females, a LOAELadj of 34.4 mg/kg-day and a NOAELadj of 6.88 mg/kg-day are identified.
Tumor incidences, which the study authors reported using a life-table method as well as
the Naive method (see Table B.5), increased in a dose-related manner in the liver (malignant and
benign) and adrenal gland, with higher incidences noted in female rats as compared to controls.
Tumors of the pituitary and mammary glands were also noted, but these tumors did not exhibit a
dose-response trend, but like the liver and adrenal tumors, appeared at a higher incidence rate in
female rats compared to male rats. Low tumor incidences were observed in other organs
(thyroid, brain, kidneys, mammary glands, uteri, urinary bladder, vagina, and skin), but these
incidences were reported not to be dose related. The authors reported no other dose-related
histological and pathological findings in any of the organs examined, with the exception of
tumor-like nodules in the liver of both male and female rats as stated above.
NCI (1979) conducted a 2-year chronic carcinogenicity peer-reviewed study in mice and
rats. In the 2-year chronic carcinogenicity study in rats conducted by NCI (1979), the study
authors administered 4-chloro-2-methylaniline hydrochloride (purity >99%) in the diet to
50 F344 rats per sex per dose group at doses of 1250 or 5000 ppm for 107 weeks. The
corresponding control group fed diet alone consisted of 20 F344 rats/sex. The corresponding
HEDs are 0, 26.8, or 107 mg/kg-day for males and 0, 27.4, or 110 mg/kg-day for females. Rats
were evaluated as described for the subchronic-duration rat study (NCI, 1979) with the following
changes. The study authors recorded body weights monthly, except for Weeks 50-90 and
96-104, in which no body weight data were collected. All animals were examined twice per
day, and observations were also made for moribund and sick, tumor-bearing animals. Clinical
examination and palpations for masses were conducted monthly during the duration of the study,
and at termination. All surviving animals were sacrificed at the end of treatment and were
necropsied. A gross and microscopic examination on major tissues, major organs, and all gross
lesions was also performed. Microscopic examination was performed on skin, lungs and
bronchi, trachea, femur bone marrow, spleen lymph nodes, thymus, heart, salivary glands, liver
pancreas, esophagus, stomach, small and large intestines, kidneys, urinary bladder, pituitary,
adrenal glands, thyroid, parathyroid, testes, prostate, mammary glands, uteri, ovaries, brain, and
all tissue masses. When possible, peripheral blood smears were made.
Treatment with oral 4-chloro-2-methylaniline hydrochloride lead to reduced mean body
weights in male and female rats exposed to the high dose as compared to controls (NCI, 1979).
Treatment did not affect mortality in a dose-related manner in either male or female rats during
the study. Other treatment-related clinical signs were not observed. Histopathology revealed a
dose-related increase of adenomas of chromophobe cells of the pituitary gland in both sexes as
compared to controls (see Table B.6). All of these adenomas were found to be benign, although
in nine rats, compression of the hypothalamus was observed. On page 23 of the report, the study
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authors noted that this effect "may be considered to be compound related on the basis of this
study," but they note that this type of tumor is common (21%) in controls rats of this strain
(NCI, 1979). A number of inflammatory and degenerative lesions were found in controls and
dosed rats but were mild in nature and not considered compound related. The results of the
statistical analysis of these effects were equivocal. Analysis of the incidence of chromophobe
adenomas of the pituitary in male rats showed the increase to be significant by the
Cochran-Armitage test but was not significant by the Fisher's exact test. In female rats, the
incidence of this tumor type was not significant by the Cochran-Armitage test, but it was
significant at the high-dose level comparison against controls by the Fisher's exact test. Based
on the histopathological findings, the study authors conclude that 4-chloro-2-methylaniline was
not carcinogenic to F344 rats in the conditions used for this assay. Based on increased of
pituitary adenomas in both males and females, a LOAELHed of 107 mg/kg-day and a NOAELHed
of 26.8 mg/kg-day are identified. This study is not selected to support the development of a
p-OSF because rats appear to be a less sensitive model of the effects of 4-chloro-2-methylaniline
administered orally, as compared to mice.
In a study parallel to the chronic-duration rat study, NCI (1979) conducted a
chronic-duration/carcinogenicity mouse study. The study authors administered neat
4-chloro-2-methylaniline hydrochloride in the diet to groups of 50 B6C3F1 mice per sex per
dose group with doses of 3750 or 15,000 ppm and 1250 or 5000 ppm of 4-chloro-
2-methylaniline, respectively (purity >99%) in the diet for 99 weeks, except for the high-dose
females, which were exposed for 92 weeks (NCI, 1979). The corresponding control group fed
the diet alone consisted of 20 mice/sex. The corresponding HEDs were 0, 98.4, or
393 mg/kg-day for males and 0, 32.8, or 131 mg/kg-day for females. Mice were evaluated as
described for the rat chronic-duration study (NCI, 1979) with the following changes: The study
authors recorded body weights, clinical findings, and palpations for masses monthly for the
duration of the study, and at termination.
Treatment with oral 4-chloro-2-methylaniline hydrochloride led to reduced body weights
throughout the study duration in male and female mice at the two administered doses when
compared to the control group, with females exhibiting a more notable effect (NCI, 1979).
Treatment significantly affected mortality in both male and female mice over the course of the
study. Histopathology revealed a dose-related significant increase of hemangiosarcoma in both
sexes (see Table B.7). Furthermore, the combined incidence of hemangiosarcomas and
hemangiomas were dose related and significantly higher than control, which is consistent with
the findings of the Weisburger et al. (1978) mouse study (see below). Tumor morphology was
highly variable. The study authors reported the bulk of the hemangiosarcoma to be composed of
large hematomatous masses of necrotizing extravasated blood, with tumor tissue at the periphery.
These lesions were associated with hemorrhage of the peritoneal cavity and variable enlargement
of the spleen, which appeared to be produced by an increase of extramedullary hemapoiesis from
the continued hemorrhaging from the tumors.
Benign hemangiomas in the genital fat were discovered in one male and one female
mouse in the low-dose groups. Hemangiomas in other organs and tissues were found at a low
rate of incidence. A high incidence rate of hemosiderin deposition in the renal tube epithelia was
found in concurrence with the hemangiosarcoma (43/119 mice), while a lesser concurrence of
hydronephrosis with the hemangiosarcoma (10/119 mice) was noted and assumed to be from the
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compression of the ureters by the tumor. Inflammatory and degenerative lesions were seen at a
low rate of incidence, seemingly due to the hemangiosarcoma. Additionally, pulmonary
metastasis was found at a low rate of incidence (5/119 mice), but this tumor, when present,
proved to be lethal (75%), resulting from hemorrhage in the peritoneal cavity and the
space-consuming nature of the lesions (NCI, 1979). Increased vascular tumors reached statistical
significance at the lowest dose in females and support a LOAELHed of 32.8 mg/kg-day. Because
the increase in tumor incidence was seen in the lowest dose-level group, a NOAEL cannot be
identified. This study, while scientifically acceptable and well conducted, does not support the
development of a p-OSF due to the lack of a dose response in the incidence of the tumors.
The study by Weisburger et al. (1978) is selected as the principal study for deriving
the p-OSF. Weisburger et al. (1978) conducted a study on the carcinogenicity of 21 aromatic
amines and amine derivatives, including 4-chloro-2-methylaniline hydrochloride (97-99% pure),
on CD rats and HaM/ICR-derived CD-I mice. The study authors administered 0, 750, or
1500 mg/kg neat material in the diet to 25 males per dose and 0, 2000, or 4000 mg/kg in the diet
of 25 females per dose for 7 days per week, for 18 months (Weisburger et al., 1978). The
corresponding HEDs were 0, 19.7, or 39.4 mg/kg-day and 0, 52.5, or 105 mg/kg-day for males
and females, respectively. Following 18 months of treatment, all animals were maintained on a
control diet for an additional 3 months. Simultaneous controls of 14 male mice and 15 female
mice were fed an untreated diet over the same period. Pooled controls included the simultaneous
controls, as well as the simultaneous controls from the studies of other chemicals presented in
this paper. The study authors conducted necropsies on all animals that died after 6 months of
exposure, and all surviving animals were sacrificed at the termination of the study. Examination
of all sacrificed animals included histopathological examination of all abnormal organs, tumor
masses, lungs, spleen, liver, kidneys, adrenal glands, heart, bladder, stomach, intestines, and
reproductive organs.
The study authors reported that exposures produced statistically significant (Fisher's
Exact Test,/? < 0.05) increases in vascular tumor incidence (hemangiosarcoma and hemangioma)
among male and female mice at all dose levels as compared to simultaneous controls (see
Table B.8). Weisburger et al. (1978) noted that these tumors arose primarily in the spleen and
subcutaneous or subperitoneal fat (data not provided). Incidences of the multiple tumors were
significant in male mice in the low-dose group when compare to the pooled controls. Based on
increased vascular tumor incidence, a LOAEL of 19.7 mg/kg-day is identified. A NOAEL is not
identified because the increase in tumor incidence was seen in the lowest dose level group. The
study supports the development of a p-OSF because it has been peer reviewed and performed
according to Good Laboratory Practice (GLP) principles and meets the standards of study design
and performance.
In a study parallel to the chronic-duration mouse study, Weisburger et al. (1978)
administered neat 4-chloro-2-methylaniline hydrochloride (purity not reported) in the diet of
male CD rats at 0, 3000, or 6000 mg/kg for 3 months followed by 0, 500, or 1000 mg/kg for
15 months. The calculated HEDs are 0, 35.4, and 70.8 mg/kg-day. After 15 months of
treatment, all rats were fed a control diet for an additional 6 months prior to study termination.
Animals that died during the first 6 months of the study were not necropsied; however, animals
that died or were sacrificed at study termination received a complete necropsy. Histopathology
of all sacrificed animals included examination of all abnormal organs, tumor masses, lungs,
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spleen, liver, kidneys, adrenal glands, heart, bladder, stomach, intestines, pituitary gland, and
reproductive organs. The study authors reported that, in general, 4-chloro-2-methylaniline was
inactive in rats; however, one male rat in the high-dose (6000-mg/kg) group exhibited a
mesothelioma that showed a large amount of involvement of the pleural and pericardial surfaces.
The authors concluded that this tumor was likely not due to exposure to
4-chloro-2-methylanaline. This study is not selected to support the development of a p-OSF due
to the generally inactive response in male rats exposed to 4-chloro-2-methylaniline.
Developmental and Reproduction Studies—4-Chloro-2-methylaniline was tested for
reproductive toxicity in 125 male F0 NMRI/SPF mice by Lang and Alder (1982). The study
authors administered 200 mg/kg-day aqueous 4-chloro-2-methylaniline by gavage 7 days per
week, for 7 weeks. The study authors weighed the animals at the termination of exposure and
placed them in cages with two untreated females for 7 days. Litter sizes were reported at birth
and at weaning. The study authors evaluated the reproductive performance of F1 males at
3-8 months of age using the sequential decision procedure on litter sizes.
The study authors reported no significant reproductive effects in the F0 or F1 generation
from F0 4-chloro-2-methylaniline exposure (Lang and Adler, 1982). Using mean litter size, as
compared to simultaneous positive (Tretamine) and negative (vehicle) controls, the authors
concluded that there was no dominant lethality in the F1 generation in treated groups. The
frequency of observed matings was not reported to have changed compared to controls. The
study authors concluded, and the data support that 4-chloro-2-methylanlinline does not produce
adverse reproductive effects under these conditions. A NOAEL of 200 mg/kg-day is identified.
Inhalation Exposures
Short-term Studies—No studies could be located regarding the effects of short-term oral
exposure to 4-chloro-2-methylaniline.
Subchronic-Duration Studies—No studies could be located regarding the effects of
subchronic inhalation exposure of animals to 4-chloro-2-methylaniline.
Chronic-Duration Studies—No studies could be located regarding the effects of chronic
inhalation exposure of animals to 4-chloro-2-methylaniline.
Developmental and Reproductive Studies—No studies could be located regarding the
effects of inhaled 4-chloro-2-methylaniline on reproduction and fetal development.
Other Exposures
No studies could be located regarding the effects of exposure of animals via other routes
to 4-chloro-2-methylaniline.
OTHER DATA (SHORT-TERM TESTS, OTHER EXAMINATIONS)
A few studies on the toxicokinetics of 4-chloro-2-methylaniline are available
(Bentley et al., 1986; Hill et al., 1979; Struck et al., 1978; Leslie et al., 1988). Results of
available studies indicate that 4-chloro-2-methylaniline undergoes distribution to primarily the
liver and kidney in rodents, but the specific distribution seems to be species dependent. These
studies also indicate that 4-chloro-2-methyalniline is metabolized in rodents, and this
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metabolism, though not completely understood, seems to be responsible for the observed
toxicity. Furthermore, 4-chloro-2-methylaniline or its metabolites are capable of binding
macromolecules in rodent liver and kidney; in the case of the rat liver in vitro, the binding to
DNA is NADPH-dependent and involves the cytochrome P-450 pathway.
The genotoxicity of 4-chloro-2-methylaniline has been tested in several studies using in
vitro test systems (McGregor et al., 1988; Galloway et al., 1987; Goggelmann et al., 1996;
IARC, 2000). These test results generally indicate that 4-chloro-2-methylaniline does not have
mutagenic activity when tested in bacteria, while the majority of mammalian tests indicate some
genotoxicity, with unclear results from chromosome aberration tests. Although there is only one
study investigating the genotoxic potential of 4-chloro-2-methylaniline in vivo, the results
demonstrate that oral exposure can induce DNA damage in the tissues of mice and rats
(Sekihashi et al., 2002), although no heritable translocations were found in spermatocytes from
F1 mice (Lang and Adler, 1982). The literature on the mutagenic action of
4-chloro-2-methylaniline is equivocal, and further investigations are needed before a conclusive
mechanism of action can be established.
Table 3 summarizes the toxicokinetics and genotoxicity studies.
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Table 3. Other Studies
Tests
Materials & Methods
Results
Conclusions
References
Toxicokinetic
Six male S-D rats were administered 10 or
100 mg/kg 4-chloro-2-methylaniline in corn oil
by intraperitoneal injection for 7 consecutive
days.
Animals sacrificed 24 hours after the final
dose, and liver microsomes, along with
proteins, were isolated.
Significantly (p < 0.05)-induced
cytochrome P-450, ethoxyresorfin-O-
deethylase (18-fold increase at
100 mg/kg), ethoxycoumarin-O-
deethylase, epoxide hydrolase, and
glutathione ^-transferase. Aminopyrine
\-dcmcthylasc was not affected.
Increased 7a, 16(3 (3-fold), and
16a (1.6-fold) hydroxylase. Testosterone
decreased.
SDS-PAGE of liver microsomes showed
protein increase in treated animals at
MW 54 kD.
4-chloro-2-methylaniline appears
to be metabolized in microsomes
through the P-450c and P-450d
pathways, as marked by
increases in ethoxyresorufin-O-
deethylase and
cthoxycoumari n-O-dccthvlasc.
notably at the low dose as well as
the high dose. Induction of
P-450c and P-450d supported by
results of SDS-PAGE.
(Leslie et al., 1988)
Toxicokinetic
Five Osborne-Mendel rats (sex not reported)
were administered 14 mg/kg of 4-chloro-
2-[methyl-uC] methylaniline hydrochloride in
0.9% sodium chloride solution by
intraperitoneal injection for 24 hours.
Following sacrifice at 24 hours,
macromolecules, DNA, RNA, and proteins
were isolated.
4-chloro-2-|»/£'Z/n7-' 4C] -methylaniline
bound most highly in the liver, where
more radioactivity was measured than in
all other organs combined.
In vitro, liver microsomes showed
NADPH-dependent binding that increased
with phenobarbital pretreatment.
Two soluble products were identified by
mass spectrometry and chemical synthesis
from the microsomes: 5-chloro-
2-hydroxylaminotoluene and
4,4'-dichloro-2,2'-dimethylazobenzene.
Results of the in vitro portion of
the study indicate binding is
catalyzed by liver microsomes
and is irreversible. Results of
pretreatment with phenobarbital,
a cytochrome P-450 inducer,
suggest that cytochrome P-450
pathway is in the binding
process.
(Hill et al., 1979;
Struck et al., 1978)
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Table 3. Other Studies
Tests
Materials & Methods
Results
Conclusions
References
Toxicokinetic
Male mice and Sprague-Dawley rats were
administered 25 mg/kg 4-[14C] chloro-2-
methylaniline hydrochloride by gavage in one
dose and were sacrificed 18 or 37 hours later,
or were treated for 14 days and were sacrificed
18 hours after last treatment.
Following sacrifice, DNA, RNA, and protein
fractions were isolated from the livers. Single
cell suspensions were prepared from mouse
livers.
In vitro, liver supernatant fractions were
combined with 4.8 mg calf thymus DNA and
11 mM 4-[14C] chloro-2-methylaniline
hydrochloride and were incubated for
30 minutes.
4-[14C] chloro-2-methylaniline
hydrochloride bound DNA in mice and
rats (p < 0.01), with binding decreasing
from 12 to 68 hours, but at all time points,
mouse liver DNA bound to a greater
extent than rat liver DNA (roughly
2-fold). Binding was greater in RNA and
protein fractions, than in DNA, and was
greater in rats than mice.
Isolated mouse liver cells showed more
binding in nonparenchymal cell DNA than
in whole liver DNA at early time points,
but the trend reversed at later time points.
Mouse liver supernatant fractions were
more successful in binding calf thymus
DNA than rat fractions.
Hepatic mouse DNA bound
more 4-[14C] chloro-2-
methylaniline hydrochloride than
rat, with amounts decreasing in
both species over time
attributable to DNA repair.
Binding was found to be
proportional to the total
administered dose and showed
mouse liver DNA to be a much
more potent binder, per dose,
than rat liver DNA. Similarly, in
vitro studies showed mouse liver
microsomal fractions more
efficiently catalyzed metabolites,
which bound to the calf thymus
DNA, than did the rat fractions,
with the reverse observed for
protein binding. This result
implies that two species may
produce different metabolic
intermediates, or that binding of
proteins may protect DNA in rat
livers. Results in
nonparenchymal cells could not
support susceptibility of mice to
tumor induction in blood vessel
endothelial cells. It was
suggested that 4-chloro-
2-methylaniline may be
preferentially activated at that
target.
(Bentley et al.,
1986)
Genotoxicity
L5178Y tk +/- mouse lymphoma cell forward
mutation assay, with and without metabolic
activation.
Test results indicate that 4-chloro-
2-methylaniline has no mutagenic activity,
with or without metabolic activation.
Result suggests that in this in
vitro assay, 4-chloro-
2-methylaniline is not genotoxic.
(McGregor et al.,
1988)
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Table 3. Other Studies
Tests
Materials & Methods
Results
Conclusions
References
Genotoxicity
Tested for reverse mutation in Salmonella
typhimurium (Ames assay) with and without
metabolic activation using TA1535, TA1537,
TA98, and TA100 strains. TA100 was
exposed to a 100-|ig/platc. TA1535 and
TA1537 were exposed to a 1500-|ig/plate.
TA98 was exposed to a 375-(ig/plate.
Chromosomal aberrations and sister chromatid
exchange were observed in human
lymphocytes.
Induction of spindle disturbances in
V79 Chinese hamster ovary (CHO) cells was
observed.
No mutations were found in Salmonella
typhimurium strains without metabolic
activation. With S9 metabolic activation
revertants observed in TA100 and TA98 at
rates 2-fold over control.
No structural or numerical changes were
observed in mammalian cells, with or
without metabolic activation.
In presence of metabolic (S9)
activation, 4-chloro-
2-methylaniline active in TA100
(base substitutions) and TA98
(frameshift mutations).
Differences between this result
and other negative published
Ames test results are thought to
be due to protocol differences
and dose ranges. Other results
indicate that standard
mammalian test did not show
genotoxicity.
(Goggelmann et al.,
1996)
Genotoxicity
125 F0 NMRI/SPF male mice administered
200 mg/kg 4-chloro-2-methylaniline by gavage
7 days/week, for 7 weeks, then bred with
untreated females. Resulting F1 males tested
for cytogenicity.
Spermatocytes from sterile, partially
sterile, or unclassifiable (1025) F1 mice
did not show a significant increase in
heritable translocation events.
Results from negative and
positive controls in
two-generation study were as
expected, but no cytogenicity
was found in 4-chloro-
2-methylaniline-exposed male
offspring.
(Lang and Adler,
1982)
Genotoxicity
Four mice or rats were administered 600 mg/kg
4-chloro-2-methylaniline in olive oil orally.
Stomach, colon, liver, kidney, bladder, lung,
brain, and bone marrow were then sampled at
3, 8, and 24 hours following exposure for a
Comet Assay of DNA damage.
DNA damage (p < 0.01) in mice found in
liver, bladder, lung, and brain 24 hours
following last exposure to 4-chloro-
2-methylaniline. DNA damage in brain
was also found at significant levels
3 hours following last dose. In rat,
significant DNA damage was found in the
liver at all time points and in the kidney
after 24 hours.
4-chloro-2-methylaniline was
positive in both mice and rats in
a Comet Assay.
Comparisons of chemicals tested
showed certain organs in a given
species may be more sensitive to
genotoxicity. Kidney cells were
found to be more sensitive in rats
than mice, while the liver was
very sensitive in mice.
(Sekihashi et al.,
2002)
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Table 3. Other Studies
Tests
Materials & Methods
Results
Conclusions
References
Genotoxicity
CHO cells exposed to 50 (ig/mL and examined
for sister chromatid exchange or exposed to
400 (ig/mL and tested for chromosomal
aberrations.
Test was positive for sister chromatid
exchange events, with and without
metabolic activation, but only positive for
chromosomal aberrations with metabolic
activation, and negative without.
4-chloro-2-methylaniline was
positive for cytogenicity.
Chromosomal aberrations
depend on the metabolic fraction
in this assay.
(Galloway et al.,
1987)
Genotoxicity
Tested for reverse mutation in Salmonella
typhimurium (Ames assay) with and without
metabolic activation using TA1535, TA1537,
TA98, and TA100 strains.
TA100 exposed to 333 (ig/plate, with and
without metabolic activation, while other
strains exposed to 1000 (ig/plate, with and
without metabolic activation.
Test was negative for reverse mutations in
all strains, under all conditions.
Negative result for mutagenicity
in the Ames assay.
The original source
of Haworthet
al.,1983 was
unavailable for
review at this time.
(IARC, 2000).
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DERIVATION OF PROVISIONAL VALUES
Table 4 presents a summary of noncancer reference values. Table 5 presents a summary
of cancer values. The toxicity values were converted to HED units. IRIS data are indicated in
the table if available.
DERIVATION OF ORAL REFERENCE DOSES
Derivation of Subchronic Provisional RfD
The subchronic-duration rat study by NCI (1979) is selected as the principal study for
derivation of a subchronic p-RfD. The critical endpoint is a 10% decrease in body weight in
female rats. This study is a range-finding study in a peer-reviewed report conducted for the
Carcinogenesis Testing Program, Division of Cancer Cause and Prevention, National Cancer
Institute, National Institutes of Health, in Bethesda, Maryland, has been performed according to
GLP principles, and meets the standards of study design and performance with regards to the
numbers of animals, and the examination of potential toxicity. Details are provided in the
Review of Potentially Relevant Data section. BMD modeling is not possible with these data
because the body-weight data were provided by the study authors in the form of mean percent
decrease from control, with no raw data or means with standard deviations. Among the available
acceptable studies, the NCI (1979) study represents the lowest credible point-of-departure (POD)
for deriving a subchronic p-RfD.
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Table 4. Summary of Noncancer Reference Values for 4-Chloro-2-Methylaniline (CASRN 95-69-2)
Toxicity type (units)3
Species/Sex
Critical Effect
p-Reference
Value
POD Method
POD
UFC
Principal Study
Subchronic p-RfD (mg/kg-day)
Rat/F
10% decrease in body
weight
5 x 10"1
NOAEL
677
1000
(NCI, 1979)
Screening chronic p-RfDb
(mg/kg-day)
Mouse/F
Absence of biologically
significant liver effects and
significant frank effects
3 x 10"3
NOAEL
3.69
1000
(Ciba-Geigy, 1992b)
Subchronic p-RfC (mg/m3)
None
Chronic p-RfC
None
aAll the reference values obtained from IRIS are indicated with the latest review date.
bA screening value is provided in Appendix A of this document.
Table 5. Summary of Cancer Values for 4-Chloro-2-Methylaniline (CASRN 95-69-2)
Toxicity Type
Species/Sex
Tumor Type
Cancer Value
Principal Study
p-OSF
Mouse/F
Hemangiomas or hemangiosarcomas (vascular
tumors)
1 x 101 per mg/kg-day
(Weisburger et al.,
1978)
p-IUR
None
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Of the two subchronic-duration studies considered for the derivation of the subchronic
p-RfD, the NCI (1979) subchronic-duration study in rats with decreased body-weight changes in
females gives the lowest LOAEL (700 mg/kg-day) and NOAEL (677 mg/kg-day). The NCI
(1979) subchronic-duration study in mice provides a LOAEL more than four times higher for the
same endpoint, thereby supporting the selection of the NCI (1979) study as the principal study.
Because the study administered 4-chloro-2-methylaniline hydrochloride, the p-RfD is adjusted to
reflect the molecular weight difference between 4-chloro-2-methylaniline and the salt form.
The POD in this study is a NOAEL of 677 mg/kg-day in female rats from principal
study data (i.e., NCI, 1979]).
Adjusted points for daily exposure:
The following dosimetric adjustments were made for each dose in the principal study for
diet treatment in adjusting for daily exposure.
NOAELadj = NOAELx x Food Consumption per Day
x (1 -h Body Weight) x (Days Dosed ^ Total Days)
= 6000 mg/kg x 0.014 kg/day x (1 -h 0.124 kg)
x (49 days dosed ^ 49 total days)
= 84 mg/day x 8.06 kg-1 x 1
= 677 mg/kg-day x 1
= 677 mg/kg-day
A subchronic p-RfD is developed as follows:
Subchronic p-RfDsait = NOAELadj ^ UFC
= 677 mg/kg-day ^ 1000
= 0.68 mg/kg-day or 7 x 10 1 mg/kg-day
Subchronic p-RfDbase =	MW of base + MW of salt x p-RfDsait
=	141.6 - 178.07 x 0.68 mg/kg-day
=	0.80 x 0.68 mg/kg-day
=	0.54 mg/kg-day or 5 x 10_1 mg/kg-day
Tables 6 and 7 summarize the uncertainty factors (UFs) and the confidence descriptors
for the 4-chloro-2-methylaniline subchronic p-RfD, respectively.
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Table 6. Uncertainty Factors for Subchronic p-RfD of 4-Chloro-2-Methylanilinea
UF
Value
Justification
ufa
10
A UFa of 10 is applied for interspecies extrapolation to account for potential
toxicokinetic and toxicodynamic differences between rats and humans. There are no data
to determine whether humans are more or less sensitive than rats to the subchronic
toxicity of 4-chloro-2-methylaniline.
ufd
10
A UFd of 10 is selected because there are no acceptable two-generation reproduction
studies or developmental studies, and there is no indication of any other studies that may
be relevant for the database uncertainty factor.
UFh
10
A UFh of 10 is applied for intraspecies differences to account for potentially susceptible
individuals in the absence of information on the variability of response in humans.
ufl
1
A UFl of 1 is applied because the POD was developed using a NOAEL.
UFS
1
A UFS of 1 is applied because a subchronic study (NCI [1979]) was utilized as the
principal study.
UFC <3000
1000

aNCI (1979).
The confidence of the subchronic p-RfD for 4-chloro-2-methylaniline is medium as
explained in Table 7.
Table 7. Confidence Descriptor for Subchronic p-RfD for 4-Chloro-2-Methylaniline
Confidence Categories
Designation"
Discussion
Confidence in study
M
Confidence in the key study is medium. NCI (1979) was a
preliminary range-finding study for a longer-term study to follow,
but assessed 10% decrease in body weight in an appropriate
number of animals. A NOAEL is identified, and the key study is
supported by similar observations in the chronic-duration study in
rats conducted by NTP (1979).
Confidence in database
M
The database includes subchronic- and chronic-duration toxicity
studies in two species (rats and mice), no developmental toxicity
studies, and a two-generation reproduction study.
Confidence in subchronic
p-RfDb
M
The overall confidence in the subchronic p-RfD is medium.
aL = Low, M = Medium, H = High.
bThe overall confidence cannot be greater than the lowest entry in the table.
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Table 8 summarizes the relevant oral systemic toxicity studies for
4-chloro-2-methylaniline.
Table 8. Summary of Oral Systemic Toxicity Studies for 4-Chloro-2-Methylaniline
References
# Sex
(M/F),
Species
Exposure
(mg/kg-day)
Frequency/
Duration
NOAELadj"
(mg/kg-day)
LOAELADJb
(mg/kg-day)
Critical Endpoints
NCI (1979)
5/5, rat
Male ADJ: 25, 50,
100, 200, 400, 600,
620, 650, 700, 800,
1000
Female ADJ: 113,
282, 339, 452, 677,
700, 734, 790, 903,
1130, 1410, 2820,
5650
7 d/wk for
7 wks in the
diet
677
700
10% decrease in
mean body weight
in females
Ciba-Geigy
(1992a)
30/30,
rat
Male ADJ: 1.38,
6.88, 34.3
Female ADJ: 1.64,
8.20,41.0
7 d/wk for 94
and 104 wks
for males and
females,
respectively, in
the diet
8.20
34.4
Increased liver
weight in males and
females
NCI (1979)
5/5,
mouse
Male ADJ: 361,722,
902, 1350, 1800,
2710
Female ADJ: 2930,
3410,3900
7 d/wk for
7 wks in the
diet
1800
2710
10% decrease in
mean body weight
in males and
females
Ciba-Geigy
(1992b)
30/30,
mouse
Male ADJ: 3.60,
18.0, 89.9
Female ADJ: 3.69,
18.4, 89.9
7 d/wk for
18 mos in the
diet
3.69
18.0 (FEL)
Increased mortality
in males and
females; increased
serum glutamic
pyruvic
transaminase
(SGPT) in females.
aNOAELADj = NOAEL x (average food intake) x (1/body weight) x (feeding schedule).
bLOAELADJ = LOAEL x (average food intake) x (1/body weight) x (feeding schedule).
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Derivation of Chronic Provisional RfD
No chronic p-RfD can be derived for the following reason: a nonpeer-reviewed study is
selected as the principal study for the chronic p-RfD; however, Appendix A of this document
contains a screening value that may be useful in certain instances. Please see the attached
Appendix A for details.
DERIVATION OF INHALATION REFERENCE CONCENTRATIONS
Derivation of Subchronic Provisional RfC
For the reasons noted in the main document, it is inappropriate to derive a provisional
subchronic RfC for 4-chloro-2-methylaniline. No quantitative human or animal studies
examining the effects of subchronic inhalation exposure to 4-chloro-2-methylaniline have been
located. Derivation of a screening value is precluded.
Derivation of Chronic Provisional RfC
For the reasons noted in the main document, it is inappropriate to derive a provisional
chronic p-RfC for 4-chloro-2-methylaniline. No quantitative human or animal studies examining
the effects of chronic inhalation exposure to 4-chloro-2-methylaniline have been located.
Derivation of a screening value is precluded.
CANCER WEIGHT-OF-EVIDENCE DESCRIPTOR
Table 9 identifies the cancer WOE descriptor for 4-chloro-2-methylaniline.
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Table 9. Cancer WOE Descriptor for 4-Chloro-2-Methylaniline
Possible WOE Descriptor
Designation"
Route of Entry (Oral,
Inhalation, or Both)
Comments
"Carcinogenic to
Humans "
N/A
N/A
No human cancer studies are available.
"Likely to Be Carcinogenic
to Humans "
X
Oral administration by
diet only
Under the Guidelines for Carcinogen Risk Assessment (U.S. EPA, 2005), the available evidence
for oral exposure to 4-chloro-2-methylaniline implies likely carcinogenicity based on evidence
of carcinogenicity in mice in the NCI (1979) study and the Weisburger et al. (1978) oral
bioassay, as well as limited human data. Results of the Weisburger et al. (1978) bioassay show
significant increases over the ranges for historical controls and significant positive trends for
vascular tumors observed mainly in the spleen or adipose tissue (hemangiomas and
hemangiosarcomas combined) in male and female mice treated orally for 18 months (see
Table B.8). In addition, the occurrence of hemangiosarcomas and hemangiomas and
hemangiosarcomas originating from adipose tissue in the NCI (1979) study shows a similar
significant positive trend during a 2-year period and also increases over ranges for historical
controls. Thus, 4-chloro-2-methylaniline is included in the 11th Report on Carcinogens, which
concludes that it is "Reasonably Accepted to be a Human Carcinogen" (NTP, 2005).
Exposure-related tumors have not been observed in male or female rats exposed to oral
4-chloro-2-methylaniline for 18 months and 2 years (Weisburger et al., 1978; NCI, 1979).
Studies evaluating the carcinogenic potential of inhaled 4-chloro-2-methylaniline animals were
not located. Occupational studies indicate carcinogenic potential, although the doses and routes
were not controlled or measured (Stasik, 1988; Popp et al., 1992; Ott and Langner, 1983).
"Suggestive Evidence of
Carcinogenic Potential"
N/A
N/A
The evidence from human and animal data is more than suggestive of carcinogenicity, which
raises a concern for carcinogenic effects, and is judged sufficient for a stronger conclusion.
"Inadequate Information to
Assess Carcinogenic
Potential"
N/A
N/A
There is adequate available information to assess carcinogenic potential.
"Not Likely to Be
Carcinogenic to Humans "
N/A
N/A
No strong evidence of noncarcinogenicity in humans is available.
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MODE-OF-ACTION DISCUSSION
The Guidelines for Carcinogen Risk Assessment (U.S. EPA, 2005) define mode of action
as a sequence of key events and processes starting with the interaction of an agent with a cell,
proceeding through operational and anatomical changes, and resulting in cancer formation.
Examples of possible modes of carcinogenic action include mutagenic, mitogenic, anti-apoptotic
(inhibition of programmed cell death), cytotoxic with reparative cell proliferation, and immune
suppression.
The mechanism of 4-chloro-2-methyaniline-induced carcinogenicity has not yet been
determined; however, available evidence suggests that vascular tumors (hemangiomas and
hemangiosarcomas) observed in mice following oral exposure to 4-chloro-2-methylaniline may
arise from genetic mechanisms. Other potential modes of action for 4-chloro-2-methylaniline-
induced hemangiomas and hemangiosarcomas have not yet been identified.
Mutagenic Mode of Action
Key Events—Numerous studies using in vitro test systems provide evidence that
4-chloro-2-methylaniline has mutagenic activity in mammalian systems in vitro, although
evidence of genotoxic activity in vivo is lacking. In bacteria, conflicting results have been
reported with 4-chloro-2-methylaniline, both in the presence and in the absence of metabolic
activators (IARC, 1990). At least one study author believes these inconsistencies may reflect
sensitivity to the particular metabolic system used in the assay (Goggelmann et al., 1996). In
mammalian cells, 4-chloro-2-methylaniline-induced sister chromatid exchanges in Chinese
hamster ovary (CHO) cells (Galloway et al., 1987), and unscheduled DNA synthesis in primary
rat hepatocytes (IARC, 1990). The Galloway et al. (1987) reported positive results for
chromosomal aberrations in cultured CHO cells in the presence of metabolic activation and
negative results in the absence of metabolic activation. Bentley et al. (1986) attempted to look at
the susceptibility of nonparenchymal cells, but results were equivocal. Studies evaluating the
genotoxicity of 4-chloro-2-methylaniline in cells of vascular origin or in vivo in humans are
lacking.
Strength, Consistency, Specificity of Association—Although NCI (1979) reported
equivocal evidence of the potential of oral 4-chloro-2-methylaniline to induce hemangiomas and
hemangiosarcomas in mice, evidence demonstrating that 4-chloro-2-methylaniline can induce
mutagenic changes in vascular cells is lacking. Thus, data are not available to link results of
genotoxicity studies to the development of hemangiomas and hemangiosarcomas reported by
NCI (1979). There is evidence in the literature for 4-chloro-2-methylaniline and/or a metabolite
binding to macromolecules in rodents involving one or more cytochrome P-450 isomers
(Leslie et al., 1988; Hill et al., 1979; Struck et al., 1978; Bentley et al., 1986).
Dose-Response Concordance—A dose-response concordance has not been established
between the development of hemangiomas and hemangiosarcomas and mutagenesis, because in
vivo evidence of mutagenicity for 4-chloro-2-methylanilineis not available. Furthermore,
evidence is lacking on the mutagenic potential of 4-chloro-2-methylanilinein vascular cells
following in vitro or in vivo exposure.
Temporal Relationships—Hemangiosarcomas (74% males and 78% females) and
combined hemangiomas and hemangiosarcomas at all sites (82% males and 78% females) have
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been observed in mice exposed to 4-chloro-2-methylaniline for 2 years (NCI, 1979). In a similar
study, Weisburger et al. (1978) noted combined hemangiomas and hemangiosarcomas incidence
at 65% and 94% in male and female mice, respectively, treated with 4-chloro-2-methylaniline for
18 months. However, due to the lack of data on the mutagenic potential of
4-chloro-2-methylaniline in vascular cells, the temporal relationship between possible mutagenic
mechanisms and the development of hemangiomas and hemangiosarcomas could not be
assessed.
Biological Plausibility and Coherence—As mentioned previously, although several
studies provide evidence that 4-chloro-2-methylaniline is metabolized through the cytochrome
P-450 pathway and binds DNA in vivo and in vitro, no evidence is available linking mutagenesis
in vascular cells to the development of hemangiomas and hemangiosarcomas.
Conclusions—Evidence does not clearly support a mutagenic mode of action for
4-chloro-2-methylaniline tumorigenicity. Although in vitro studies provide evidence that
4-chloro-2-methylaniline is capable of eliciting genotoxic effects in mammalian cells, two key
uncertainties remain (1) data evaluating the genotoxic potential of 4-chloro-2-methylaniline in
vivo are lacking, and (2) no evidence linking mutagenesis to the development of vascular cell
tumors is available. Therefore, a default linear approach is applied.
DERIVATION OF PROVISIONAL CANCER POTENCY VALUES
Derivation of Provisional Oral Slope Factor
The study by Weisburger et al. (1978) is selected as the principal study. The critical
endpoint is the incidence of vascular tumors (hemangiosarcoma or hemangioma, all sites) in
male mice. This study is generally well conducted, and the data from this study are able to
support a quantitative cancer dose-response assessment. This study is a peer-reviewed technical
report from an investigator at the National Cancer Institute, has been performed according to
GLP principles, and meets the standards of study design and performance with numbers of
animals, examination of potential toxicity endpoints, and presentation of information. Details
are provided in the Selection of Potentially Relevant Studies section. Among the available,
acceptable studies, this study represents the highest OSF from selected studies in the database.
The Weisburger et al. (1978) 18-month carcinogenicity study yielded unequivocal
evidence in male and female mice that 4-chloro-2-methylaniline significantly induced
hemangiomas or hemangiosarcomas (vascular tumors) in both sexes at both doses tested (19.7
and 39.4 mg/kg-day for males; 52.5 and 105 mg/kg-day for females). However, because of the
nonmonotonic dose-response relationship of vascular tumor incidence in the female mice (see
Table B.8) the data set did not pass thep-walue criteria test following BMD modeling. Because
tumorigenicity at the low-dose range is of the highest interest, the high-dose group data were
removed from the female data set, and BMD modeling was re-run. This model run provided an
OSF of 0.09 per mg/kg-day. Although an adequate model fit was achieved using both low and
high doses for the male vascular tumor data set from the Weisburger et al. (1978) study due to
the monotonic nature of the dose response (see Table B.8), it provided a lower OSF than the
female data set (0.05 per mg/kg-day; see Appendix C). Additionally, when only the low dose
was used in the BMD modeling, the male data set still provided a lower OSF than the female
data set (0.07 per mg/kg-day vs. 0.09 per mg/kg-day, respectively; see Appendix C). The NCI
(1979) study also provided statistically and biologically significant data of increased vascular
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tumors in mice, and combined incidence of hemangiosarcomas or hemangiomas in male mice
resulted in a model that passed the /rvalue criteria test. However, the modeling of the male data
from the NCI (1979) study resulted in a lower OSF (0.002 per mg/kg-day) compared to the
female vascular tumor data from Weisburger et al. (1978) (Appendix C). Similar to the
Weisburger et al. (1978) study, the female data set from the NCI (1979) study did not pass the
/>value criteria test following BMD modeling because of the nonmonotonic dose-response
relationship of tumor incidence (see Table B.7). When the high-dose group data were removed,
the model run provided an OSF of 0.09 per mg/kg-day, which is identical to that derived from
the female data set from the Weisburger et al. (1978) study (see Appendix C).
The estimated OSF of 0.09 per mg/kg-day based on data on vascular tumor incidence
(hemangiomas or hemangiosarcomas) in female mice was selected for oral exposure to
4-chloro-2-methylaniline (Weisburger et al., 1978). Because the Weisburger et al. (1978) study,
like the NCI (1979) study, administered 4-chloro-2-methylaniline hydrochloride, the p-OSF is
adjusted to reflect the molecular weight difference between 4-chloro-2-methylaniline and the salt
form.
The following dosimetric adjustments were made for diet treatment in adjusting doses for
p-OSF analysis:
DOSEAdj,hed	= Dose x Food Consumption per Day x (1
+ Body Weight) x (Days Dosed + Total Days)
x body-weight adjustment
Body-weight adjustment = (BWa ^ BWh)1'4
BWh	= 70 kg (human reference body [U.S. EPA, 1997])
BWa	= 0.0317 kg (average body weight for male mice [U.S. EPA,
1994b])
Body-weight adjustment = (0.0317/70)1/4 = 0.146
(DOSEadj, hed)	= (Dose)„ x (0.0057 kg/day) x (1 - 0.0317 kg)
x (560 days/560 days) x 0.146
= 2000 mg/kg x (0.0057 kg/day) x (31.55 kg-1) x 1 x 0.146
= 11.4 mg/dayx 31.55 kg-1 x 1 x 0.146
= 359.67 mg/kg-day x 0.146
= 52.5 mg/kg-day
Table 10 presents BMD input data for incidence of vascular tumors in female mice
exposed to 4-chloro-2-methylaniline in the diet for 18 months.
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Table 10. BMD Input for Incidence of Vascular Tumors in
Female HaM/ICR Mice Exposed to 4-Chloro-2-Methylaniline in the Diet for 18 Months"



Response
(Dose)„ (mg/kg-day)
(DOSEadj,hed)«
(mg/kg-day)
Number of Subjects
Vascular Tumors,
All Sitesb c
0
0
15
0(0)
359.67
52.5
19
18(95)d
aWeisburger etal. (1978).
bNumber of mice with tumors, () = percentage of mice with lesions or tumors.
Statistically significant positive trend.
Statistically significant in pairwise test versus control.
Table 11 shows the modeling results. Adequate model fit is obtained for the vascular
tumor incidence data using the multistage cancer model. The BMD modeling results for
vascular tumors yield a BMDiohed of 1.879 mg/kg-day and a BMDLiohed of 1.070 mg/kg-day
(see Table 11).
Table 11. Goodness-of-Fit Statistics, BMDiohed, and BMDLiohed Values for
the Multistage Cancer Model for Vascular Tumors (All Sites) in Female Mice Exposed to
4-Chloro-2-Methylaniline in the Diet for 18 Months3
Model
Goodness-of-Fit
p-V alueb
AIC
BMDiohed
(mg/kg-day)
BMDLiohed
(mg/kg-day)
Multistage Cancer0
0.996
9.835
1.879
1.070
aWeisburgeretal. (1978).
bValues >0.1 meet conventional goodness-of-fit criteria.
°Betas restricted to >0.
p-OSFsait - 0.1 : BMDLiohed
= 0.1-5- 1.070 mg/kg-day
0.093 (mg/kg-day) 1 or 9 x 10 2 per mg/kg-day
p-OSFbase = MW of salt MW of base x p-OSFsait
= 178.07 - 141.6 x 0.093 mg/kg-day
-l
1.26 x 0.093 (mg/kg-day)
0.117 (mg/kg-day)-1 or 1 x 10_1 per mg/kg-day
Derivation of Provisional Inhalation Unit Risk
No human or animal studies examining the carcinogenicity of 4-chloro-2-methylaniline
following inhalation exposure have been located. Therefore, derivation of an inhalation unit risk
is precluded.
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APPENDIX A. PROVISIONAL SCREENING VALUES
DERIVATION OF SCREENING PROVISIONAL ORAL REFERENCE DOSES
Derivation of Screening Chronic Provisional RfD
For reasons noted in the main PPRTV document, it is inappropriate to derive provisional
toxicity values for 4-chloro-2-methylaniline. However, information is available for this chemical
which, although insufficient to support derivation of a provisional toxicity value, under current
guidelines, may be of limited use to risk assessors. In such cases, the Superfund Health Risk
Technical Support Center summarizes available information in an appendix and develops a
"screening value." Appendices receive the same level of internal and external scientific peer
review as the PPRTV documents to ensure their appropriateness within the limitations detailed in
the document. Users of screening toxicity values in an appendix to a PPRTV assessment should
understand that there is considerably more uncertainty associated with the derivation of an
appendix screening toxicity value than for a value presented in the body of the assessment.
Questions or concerns about the appropriate use of screening values should be directed to the
Superfund Health Risk Technical Support Center.
The study by Ciba-Geigy (1992b) is selected as the principal study for the derivation of a
screening chronic p-RfD. Based on the data from the Ciba-Geigy (1992b) study, general
biological trends can be found, and the liver appears to be a sensitive target organ of
4-chloro-2-methylaniline. Although mice exposed to 4-chloro-2-methylaniline do not exhibit
dose-related pathological or weight changes in the liver, levels of SGPT—an enzyme that is
released into the blood following liver damage—were increased and reached statistical
significance at the 18.0 mg/kg-day dose level in male mice, which is also a FEL. Additionally,
serum glutamic oxaloacetic transaminase levels were also increased in female mice by 50% and
60% in the 3.69 and 18.4 mg/kg-day dose groups, respectively; however, these changes did not
reach statistical significance. Although total serum protein level was significantly decreased at a
lower dose than SGPT (3.69 mg/kg-day), the biological significance and adversity of this
endpoint in and of itself is questionable. Additional support for liver as a sensitive target organ
is exhibited by data from the Ciba-Geigy (1992a) rat study in which liver weights were
significantly increased in males and females at the highest dose tested, and gross macroscopic
liver pathological findings were also present at the mid- and high-dose in females.
The Ciba-Geigy (1992b) study is unpublished, but it is a report submitted to EPA under
Toxic Substances Control Act Section 8ECP, and it has been performed according to GLP
principles, and it meets the standards of study design and performance with numbers of animals,
examination of potential toxicity endpoints, and presentation of information. Details are
provided in the Review of Potentially Relevant Data section. Among the available acceptable
studies, this study represents the lowest and most appropriate POD for developing a chronic
p-RfD. Because the study administered 4-chloro-2-methylaniline hydrochloride, the p-RfD is
converted to reflect the molecular weight difference between 4-chloro-2-methylaniline and the
salt form.
From the Ciba-Geigy (1992b) study, based on the absence of biologically significant liver
effects and significant frank effects (i.e., mortality) in mice at 3.69 mg/kg-day, this dose is
33
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identified as a NOAELadj for 4-chloro-2-methylaniline, and this NOAELadj was selected as the
POD for derivation of the subchronic p-RfD.
Adjusted points for daily exposure:
The following dosimetric adjustments were made for each dose in the principal study for
treatment in the diet in adjusting for daily exposure.
NOAELadj
NOAELxx Food Consumption per Day x
(1 ^ Body Weight) x (Days Dosed ^ Total
Days)
20 ppm x 0.0053 kg/day x (1 - 0.02875 kg)
x (560 days dosed ^ 560)
0.106 mg/day x 34.78 kg-1 x 1
3.69 mg/kg-day x 1
3.69 mg/kg-day
A screening chronic p-RfD is developed as follows:
Screening Chronic p-RfDsait
Screening Chronic p-RfDbase
—	NOAELadj UFc
=	3.69 mg/kg-day 1000
=	0.004 mg/kg-day or 4 x 10~3 mg/kg-day
=	MW of base + MW of salt x p-RfDsait
=	141.6 - 178.07 x 0.004 mg/kg-day
=	0.80 x 0.004 mg/kg-day
-1—3
= 0.003 mg/kg-day or 3 x 10 mg/kg-day
Table A.l summarizes the UFs for the screening chronic p-RfD for 4-chloro-2-methylaniline.
Table A.l. Uncertainty Factors for Screening Chronic p-RfD
of 4-Chloro-2-Methylanilinea
UF
Value
Justification
ufa
10
A UFa of 10 is applied for interspecies extrapolation to account for potential toxicokinetic and
toxicodynamic differences between rats and humans. There are no data to determine whether
humans are more or less sensitive than mice to the chronic toxicity of 4-chloro-2-methylaniline.
ufd
10
A UFd of 10 is selected because there are no acceptable two-generation reproduction studies or
developmental studies, and there is no indication of any other studies that may be relevant for the
database UF.
UFh
10
A UFh of 10 is applied for intraspecies differences to account for potentially susceptible individuals
in the absence of information on the variability of response in humans.
ufl
1
A UFl of 1 is applied because the POD was developed using a NOAEL.
UFS
1
A UFS of 1 is applied because a chronic-duration study (Ciba-Geigy [1992b]) was utilized as the
principal study.
UFC
<3000
1000

aCiba-Geigy (1992b).
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APPENDIX B. DATA TABLES
Table B.l. Survival and Mean Body-Weight Parameters in F344 Rats
Exposed to 4-Chloro-2-Methylaniline in the Diet for 7 Weeks3
Male
Female
Exposure Group,
ppm
(Adjusted Daily
Dose, mg/kg-day)
Survivalb
Mean Body
Weight, Day 49
(% of Control)0
Exposure Group,
ppm
(Adjusted Daily
Dose, mg/kg-day)
Survivalb
Mean Body
Weight, Day 49
(% of Control)0
First experiment

0
5/5 (100)
100



250 (25)
5/5 (100)
93



500 (50)
5/5 (100)
94



1000 (100)
5/5 (100)
95



2000 (200)
5/5 (100)
94



4000 (400)
5/5 (100)
92



Second experiment
First experiment
0
5/5 (100)
100
0
5/5 (100)
100
6000 (600)
5/5 (100)
91
6000 (677)
5/5 (100)
92
6200 (620)
5/5 (100)
98
6200 (700)
5/5 (100)
90
6500 (650)
5/5 (100)
99
6500 (734)
5/5 (100)
93
7000 (700)
5/5 (100)
92
7000 (790)
5/5 (100)
89
8000 (800)
5/5 (100)
89
8000 (903)
5/5 (100)
91
10,000 (1000)
5/5 (100)
92
10,000(1130)
5/5 (100)
90



Second experiment



0
5/5 (100)
100



1000 (113)
5/5 (100)
103



2500 (282)
5/5 (100)
101



3000 (339)
5/5 (100)
98



4000 (452)
5/5 (100)
101



Third experiment



0
5/5 (100)
100



6200 (700)
5/5 (100)
81



12,500 (1410)
5/5 (100)
67



25,000 (2820)
5/5 (100)
55



50,000 (5650)
0/5 (0)
--
aNCI (1979).
bNumber of surviving animals per number of animals exposed, () = percent of total.
Incidence, percentage of control, and independent statistics could not be provided due to a lack of information in
the study report.
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Table B.2. Survival and Mean Body Weight Parameters in B6C3F1 Mice
Exposed to 4-Chloro-2-Methylaniline in the Diet for 7 Weeks3
Exposure Group,
ppm (Adjusted Daily Dose,
mg/kg-day)
Survivalb
Mean Body Weight,
Day 49 (% of Control)0
Male
0
5/5 (100)
100
2000 (361)
5/5 (100)
103
4000 (722)
5/5 (100)
96
5000 (902)
5/5 (100)
99
7500 (1350)
5/5 (100)
97
10,000 (1800)
5/5 (100)
98
15,000 (2710)
5/5 (100)
89
Female
0
5/5 (100)
100
15,000 (2930)
5/5 (100)
90
17,500 (3410)
5/5 (100)
90
20,000 (3900)
5/5 (100)
78
aNCI (1979).
dumber of surviving animals per number of animals exposed, () = percent of total.
Incidence, percentage of control, and independent statistics could not be provided due to a lack of
information in the study report.
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Table B.3. Selected Biochemistry Parameters in ICR Mice Exposed to
4-Chloro-2-Methylaniline in the Diet for 80 Weeks"
Parameter
Exposure Group (Adjusted Daily Dose, mg/kg-day)
0 ppm
20 ppm (3.60)
100 ppm (18.0)
500 ppm (89.9)
Male mouse
Mortality
8/29 (28%)
11/30 (37%)
20/30 (67%)e
29/30 (97%)e
Sample size
21
19
10
1
Total serum protein (g/dL)b
7.23 ±1.10
5.93± 0.73 (82)°'d
6.51 ±0.96 (90)
5.20 — (72)
Blood urea nitrogenb (mg/dL)
17.21 ±3.97
21.36 ± 7.46 (124)c
19.51 ±8.59 (113)
53.00 — (308)
Glucose (g/dL)b
135.8 ±39.5
164.4 ± 23.9 (121)od
155.6 ±24.0 (115)
190.0 — (140)
Serum glutamic oxaloacetic
transaminase (mU)b
100.1 ±32.6
99.2 ± 26.0 (99)
94.7 ±15.0 (95)
92.0 — (92)
Serum glutamic pyruvic
transaminase (mU)b
24.4 ± 14.9
33.8 ±28.1 (139)
36.1 ±21.6 (148)
28.0 —(115)
Serum alkaline phosphatase
(mU)b
22.8 ± 10.7
20.2 ±12.4 (89)
24.3 ± 16.6 (107)
23.0 —(101)
Total Cholesterol (mg/dL)b
177.5 ±68.7
138.4 ±47.1 (78)c
139.9 ±60.0 (79)
61.0 — (34)
Parameter
Exposure Group (Adjusted Daily Dose, mg/kg-day)
0 ppm
20 ppm (3.69)
100 ppm (18.4)
500 ppm (92.2)
Female mouse
Mortality
13/29 (44%)
19/30 (63%)
24/29 (83%)e
28/28 (100%)e
Sample size
16
11
5
0
Total serum protein (g/dL)b
6.57 ±0.41
6.24 ± 0.37 (95)°'d
5.78 ± 0.36 (88)°'d
-
Blood urea nitrogen (mg/dL)b
15.69 ±2.96
34.53 ±28.91 (220)c,d
20.40 ± 15.36 (130)
-
Glucose (g/dL)b
117.0 ±20.8
140.5 ±44.9 (120)
137.8 ±49.8 (118)
-
Serum glutamic oxaloacetic
transaminase (mU)b
112.6 ±28.0
168.3 ± 167.8 (150)
179.6 ±201.8 (160)
-
Serum glutamic pyruvic
transaminase (mU)b
16.4 ±9.8
21.3 ±7.6 (130)
35.4 ±35.2 (216)°'d
-
Serum alkaline phosphatase
(mU)b
26.3 ±9.6
25.5 ± 10.2 (97)
28.4 ±16.8 (108)
-
Total Cholesterol (mg/dL)b
99.1 ± 15.4
123.4 ± 53.0 (125)°
97.6 ± 40.8 (99)
-
aCiba-Geigy (1992b).
bMeans ± SD, () = percent of control.
Statistically significantly different from control by independent Standard /-Test (p < 0.05) performed for this
review.
Statistically significantly different from control by independent Dunnett's Multiple Comparisons Test (p < 0.05)
performed for this review.
"Statistically significantly different from control by independent Fisher's Exact Test (p < 0.05) performed for this
review.
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Table B.4. Incidence of Selected Tumor in ICR Mice Exposed to

4-Chloro-2-Methylaniline in the Diet for 80 Weeks3


Exposure Group (Human Equivalency Dose, mg/kg-day)
Parameter
0 ppm
20 ppm (0.525)
100 ppm (2.62)
500 ppm (13.1)
Male mouse
Sample size
30
30
30
30
Liver: hepatoma and
adenomab
48.5 (26.7)
56.3 (30.0)
53.3 (27.6)
63.9 (20.7)
Lung: adenomab
38.7 (20.0)
41.4 (20.0)
8.7 (3.4)
61.4 (17.2)
Leukemia and
lymphosarcoma b
20.1 (16.7)
3.4 (3.3)
19.9(10.3)
0.0 (0.0)
Reticulum cell
7.7 (3.3)
3.8 (3.3)
0.0 (0.0)
6.2 (3.4)
sarcomab




Probably reticulum
cell sarcomab
0.0 (0.0)
8.3 (3.3)
41.8(24.1)
84.6 (20.7)
Unclassified
malignant tumorb
0.0 (0.0)
23.1 (10.0)
72.8 (48.3)
62.2 (48.3)
Tumor incidence13
72.7 (56.7)
83.3 (60.0)
96.1 (86.2)
100.0 (86.2)

Exposure Group (Human Equivalency Dose, mg/kg-day)
Parameter
0 ppm
20 ppm (0.525)
100 ppm (2.62)
500 ppm (13.1)
Female mouse
Sample size
30
30
30
30
Liver: hepatoma and
adenomab
14.8 (6.9)
7.4 (3.3)
0.0 (0.0)
18.8 (10.7)
Lung: adenomab
14.8 (6.9)
37.5 (20.0)
59.0(13.8)
10.6(7.1)
Leukemia and
lymphosarcoma b
38.0 (24.1)
17.3 (10.0)
32.8 (20.7)
3.6 (3.6)
Reticulum cell
0.0 (0.0)
0.0 (0.0)
0.0 (0.0)
0.0 (0.0)
sarcomab




Probably reticulum
cell sarcomab
0.0 (0.0)
17.3 (17.3)
14.3 (6.9)
84.9 (21.4)
Unclassified
malignant tumorb
0.0 (0.0)
70.0 (46.7)
70.8 (41.4)
87.0 (64.3)
Tumor incidence13
56.3 (37.9)
85.5 (70.0)
93.6 (79.3)
100.0 (92.9)
aCiba-Geigy (1992b).
Percentages calculated by study authors using the modified life table method, () = calculated by Naive method.
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Table B.5. Selected Tumor Incidence in Sprague-Dawley Rats Exposed to
4-Chloro-2-Methylaniline in the Diet for 94 or 104 Weeks3
Parameter
Exposure Group (Human Equivalency Dose, mg/kg-day)
0 ppm
20 ppm (0.405)
100 ppm (2.02)
500 ppm (10.1)
Male mouse
Sample size
30
30
30
30
Liver tumorb
0.0 (0.0)
11.1 (3.3)
45.1 (16.7)
80.3 (43.3)
Malignant and probably
malignant hepatoma13
0.0 (0.0)
11.1 (3.3)
12.5 (3.5)
45.5 (16.7)
Probably benign hepatoma
and adenomatous hyperplasia13
0.0 (0.0)
0.0 (0.0)
36.8(13.3)
56.1 (26.7)
Adrenal gland adenoma and
adenomatous hyperplasia13
33.3 (13.3)
47.8 (20.0)
45.1 (16.7)
38.4 (20.0)
Pituitary gland adenomab
44.7 (23.3)
71.8(36.7)
50 (16.7)
43.2 (20.0)
Total tumor incidence13
74.8 (46.7)
86.1 (56.7)
86.2 (43.3)
92.5 (56.7)
Parameter
Exposure Group (Human Equivalency Dose, mg/kg-day)
0 ppm
20 ppm (0.421)
100 ppm (2.11)
500 ppm (10.5)
Female mouse
Sample size
30
30
30
30
Liver tumorb
0.0 (0.0)
25.9(10.0)
81.8(31.0)
91.8 (66.7)
Malignant and probably
malignant hepatoma13
0.0 (0.0)
0.0 (0.0)
14.5 (3.4)
48.7 (16.7)
Probably benign hepatoma
and adenomatous hyperplasia13
0.0 (0.0)
25.9(10.0)
76.2 (27.6)
78.0 (50.0)
Adrenal gland adenoma and
adenomatous hyperplasia13
58.0 (27.6)
72.6 (40.0)
87.2 (55.2)
82.7 (53.3)
Pituitary gland adenomab
83.9 (58.6)
86.6 (60.0)
80.4 (55.2)
90.5 (60.0)
Total tumor incidence13
93.9 (82.8)
98.0 (83.3)
C
100.0 (96.7)
aCiba-Geigy (1992a).
Percentages calculated by study authors using the modified life table method, ().= calculated by Naive method.
°Values could not be determined in the study report.
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Table B.6. Selected Incidence of Neoplasms in F344 Rats Exposed to 4-Chloro-2-Methylaniline in the Diet for 107 Weeks3
Parameter
Exposure Group (Human Equivalency Dose, mg/kg-day)
0 ppm (0)
1250 ppm (26.8)
5000 ppm (107)
Tumor
Incidenceb
Weeks until First
Tumor
Tumor
Incidenceb
Weeks until
First Tumor
Tumor
Incidenceb
Weeks until
First Tumor
Male rat
Integumentary system: fibroma
1/20 (5)
107
4/50 (8)
107
2/50 (4)
107
Lung: alveolar/bronchiolar carcinoma or adenoma
1/20 (5)
107
6/50 (12)
107
2/49 (4)
107
Hematopoietic system: lymphoma or leukemia
6/20 (30)
89
1/50 (2)
92
1/50 (2)
73
Liver: hepatocellular carcinoma or adenoma
0/20 (0)
-
5/50 (10)
100
4/50 (8)
107
Pituitary: chromophobe adenoma
2/19(11)
107
6/48 (13)
92
15/47 (32)d
84
Adrenal: pheochromocytoma
0/20 (0)
-
0/49 (0)
-
4/49 (8)
107
Thyroid: follicular-cell carcinoma or adenoma
1/19 (5)
107
0/49 (0)
-
4/49 (8)
62
Testis: interstitial-cell tumor
16/20 (80)
93
39/48 (81)
92
42/50 (84)
62
Tunica vaginalis: mesothelioma, NOS
2/20 (10)
107
0/50 (0)
-
0/50 (0)
-
Parameter
Exposure Group (Human Equivalency Dose, mg/kg-day)
0 ppm (0)
1250 ppm (27.4)
5000 ppm (110)
Tumor
Incidenceb
Weeks until First
Tumor
Tumor
Incidenceb
Weeks until
First Tumor
Tumor
Incidenceb
Weeks until
First Tumor
Female rat
Hematopoietic system: lymphoma or leukemia
3/20 (15)
72
4/50 (8)
88
1/50 (2)
107
Pituitary: chromophobe adenoma
1/19 (5)
107
13/47 (28)
92
15/48 (31)°
88
Mammary gland: adenoma, NOS
0/20 (0)
-
6/50 (12)
103
1/50 (2)
107
Mammary gland: fibroadenoma
4/20 (20)
102
10/50 (20)
107
6/50 (12)
107
Uterus: endometrial stromal polyp
5/19 (26)
107
5/49 (10)
107
8/49 (16)
107
aNCI (1979).
dumber of animals with tumors/number of animals examined, () = percent of total.
Statistically significantly different from control by Fisher's Exact Test (p < 0.05) performed by the researchers.
Statistically significantly different from control by Cochran-Armitage Test (p < 0.05) performed by the researchers.
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Table B.7. Selected Incidence of Neoplasms in B6C3F1 Mice Exposed
to 4-Chloro-2-Methylaniline in the Diet for 99 Weeks3
Parameter
Exposure Group (Human Equivalency Dose, mg/kg-day)
0 ppm (0)
3750 ppm (98.4)
15,000 ppm (393.0)
Tumor
Incidence13
Weeks
until First
Tumor
Tumor
Incidence15
Weeks
until First
Tumor
Tumor
Incidence13
Weeks
until First
Tumor
Male mouse
Lung: alveolar/ bronchiolar carcinoma
2/20 (10)
99
7/46 (15)
96
1/48 (2)
95
Lung: alveolar/ bronchiolar carcinoma
or adenoma
4/20 (20)
99
14/46 (30)
96
3/48 (6)
95
Hematopoietic system: lymphoma
1/20 (5)
99
3/50 (6)
99
1/50 (2)
99
All sites: hemangioma
0/20 (0)
-
3/50 (6)
99
5/50 (10)
65
All sites: hemangiosarcoma
0/20 (0)
-
3/50 (6)
87
37/50 (74)d
66
All sites: hemangiosarcoma or
hemangioma
0/20 (0)
-
6/50 (12)
87
41/50 (82)d
65
Liver: hepatocellular carcinoma
4/20 (20)
99
5/50 (10)
99
7/50 (14)
77
Liver: hepatocellular carcinoma or
adenoma
4/20 (20)
99
7/50 (14)
99
10/50 (20)
77
Parameter
Exposure Group (Human Equivalency Dose, mg/kg-day)
0 ppm (0)
1250 ppm (32.8)
5000 ppm (131)c
Tumor
Incidence13
Weeks
until First
Tumor
Tumor
Incidence13
Weeks
until First
Tumor
Tumor
Incidence13
Weeks
until First
Tumor
Female mouse
Lung: alveolar/ bronchiolar adenoma
0/18 (0)
-
2/47 (4)
99
3/48 (6)
64
Hematopoietic system: lymphoma or
leukemia
1/18 (6)
99
6/49 (12)
72
1/50 (2)
82
All sites: hemangioma
1/18 (6)
99
6/49 (12)
65
0/50 (0)
-
All sites: hemangiosarcoma
0/18 (0)
-
40/49 (82)d
43
39/50 (78)d
66
All sites: hemangiosarcoma or
hemangioma
1/18 (6)
99
44/49 (90)d
43
39/50 (78)d
66
Liver: hepatocellular carcinoma or
adenoma
1/18 (6)
99
4/49 (8)
96
0/49 (0)
-
aNCI (1979).
bNumber of animals with tumors/number of animals examined, () = percent of total.
°Female mice in the high-dose group were only exposed for 92 weeks.
Statistically significantly different from control by Fisher's Exact Test (p < 0.05) performed by the researchers.
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Table B.8. Tumor Incidence in HaM/ICR Mice Exposed to 4-Chloro-2-Methylaniline in

the Diet for 18 Months3


Exposure Group (Human Equivalency Dose, mg/kg-day)
Parameter
Simultaneous Control (0)
Pooled Control (0)
750 mg/kg (19.7)
1500 mg/kg (39.4)
Male mouse
Vascular tumorsb
0/14 (0)
5/99 (5)
12/20 (60)°
13/20 (65)°
Multiple tumorsb
1/14 (7)
14/99 (14)
7/20 (35 )d
6/20 (30)

Exposure Group (Human Equivalency Dose, mg/kg-day)
Parameter
Simultaneous Control (0)
Pooled Control (0)
2000 mg/kg (52.5)
4000 mg/kg (105)
Female mouse
Vascular tumorsb
0/15 (0)
9/102 (9)
18/19 (95)°
12/16 (75)°
"Wcisburgcr etal. (1978).
bNumber of animals with tumors/number of animals examined, () = percent of total.
Statistically significantly different from all controls by Fisher's Exact Test (p < 0.05) performed by the researchers.
Statistically significantly different from pooled controls only by Fisher's Exact Test (p < 0.05) performed by the
researchers.
42
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FINAL
9-30-2010
APPENDIX C. BMD MODELING OUTPUTS FOR 4-CHLORO-2-METHYANILINE
T3
0)
+->
O
it
<
c
o
¦-4-'
o
ro
Multistage Cancer Model with 0.95 Confidence Level
Multistage Cancer
Linear extrapolation
0.8
0.6
0.4
0.2
BMDL
08:46 08/11 2010
Figure C.l. Multistage Cancer BMD Model for Female Vascular Tumor Incidence
(Weisburger et al., 1978)
Text Output for Multistage Cancer BMD Model for Female Vascular
Tumor Incidence Data (Weisburger et al., 1978)
Multistage Cancer Model. (Version: 1.9; Date: 05/26/2010)
Input Data File: C:/USEPA/BMDS21/Data/msc 4C2M Weisburgerl978 F Msc2-
BMR10.(d)
Gnuplot Plotting File: C:/USEPA/BMDS21/Data/msc 4C2M Weisburgerl978 F Msc2-
BMR10.pit
Wed Aug 11 08:26:17 2010
BMDS Model Run
The form of the probability function is:
P[response] = background + (1-background)*[1-EXP(
-betal*dose/sl-beta2*dose/s2) ]
43
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FINAL
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The parameter betas are restricted to be positive
Dependent variable = Incidence
Independent variable = Dose
Total number of observations = 3
Total number of records with missing values = 0
Total number of parameters in model = 3
Total number of specified parameters = 0
Degree of polynomial = 2
Maximum number of iterations = 250
Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008
Default Initial Parameter Values
Background =	0.527837
Beta(1) = 0.0132028
Beta(2) =	0
Asymptotic Correlation Matrix of Parameter Estimates
( *** The model parameter(s) -Background -Beta(2)
have been estimated at a boundary point, or have been specified by
the user,
and do not appear in the correlation matrix )
Beta(1)
Beta (1)	1
Parameter Estimates
95.0% Wald Confidence
Interval
Variable	Estimate	Std. Err. Lower Conf. Limit Upper Conf.
Limit
Background	0	* * *
Beta(1)	0.0243031	* * *
Beta(2)	0	* * *
* - Indicates that this value is not calculated.
Analysis of Deviance Table
Model
Full model
Fitted model
Reduced model
Log(likelihood)
-12.915
-18.3494
-33.6506
# Param's
3
1
1
Deviance Test d.f.
10.8688
41. 4711
P-value
0.004364
<.0001
AIC:
38.6989
Goodness of Fit
Scaled
44
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FINAL
9-30-2010
Dose
Est. Prob.
Expected
Observed
Size
Residual
0.0000
52.5000
105.0000
0.0000
0.7208
0.9221
0.000
13.696
14.753
0.000
18.000
12.000
15
19
16
0. 000
2.201
-2.567
Chi^2 = 11.44
d.f. = 2
P-value = 0.0033
Benchmark Dose Computation
Specified effect =	0.1
Risk Type =	Extra risk
Confidence level =	0.95
BMD =	4.33528
BMDL =	3.10321
BMDU =	6.39484
Taken together, (3.10321, 6.39484) is a 90	% two-sided confidence
interval for the BMD
Multistage Cancer Slope Factor =	0.0322247
45	4-Chloro-2-Methylaniline

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FINAL
9-30-2010
Multistage Cancer Model with 0.95 Confidence Level
Multistage Cancer
Linear extrapolation
1
0.8
0.6
0.4
0.2
0
fJMDL
BMD
0
10
20
30
40
50
dose
11:14 08/12 2010
Figure C.2. Multistage Cancer BMD Model for Female Vascular Tumor Incidence Data
without the High-Dose Data (Weisburger et al., 1978)
Text Output for Multistage Cancer BMD Model for Female Vascular Tumor Incidence
Data without the High-Dose Data (Weisburger et al., 1978)
Multistage Cancer Model. (Version: 1.9; Date: 05/26/2010)
Input Data File: C:/USEPA/BMDS21/Data/msc_4C2M_Weisburgerl978_F_Mscl-
BMR10.(d)
Gnuplot Plotting File: C:/USEPA/BMDS2l/Data/msc_4C2M_Weisburgerl978_F_Mscl-
BMR10.pit
Thu Aug 12 11:14:34 2010
BMDS Model Run
The form of the probability function is:
P[response] = background + (1-background)*[1-EXP(
-betal*dose/sl) ]
The parameter betas are restricted to be positive
Dependent variable = Incidence
46
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FINAL
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Independent variable = Dose
Total number of observations = 2
Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1
Maximum number of iterations = 250
Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008
Default Initial Parameter Values
Background =	0
Beta(1) = 0.0560846
Asymptotic Correlation Matrix of Parameter Estimates
( *** The model parameter(s) -Background
have been estimated at a boundary point, or have been specified by
the user,
and do not appear in the correlation matrix )
Beta(1)
Beta (1)	1
Parameter Estimates
95.0% Wald Confidence
Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf.
Limit
Background	0	*	*	*
Beta(1)	0.0560846	*	*	*
* - Indicates that this value is not calculated.
Analysis of Deviance Table
Model
Full model
Fitted model
Reduced model
Log(likelihood)
-3.91765
-3.91768
-23.5081
# Param's	Deviance	Test d.f.	P-value
2
1	6e-005	1	0.9938
1	39.181	1	<.0001
AIC:
9.83536
Goodness of Fit
Scaled
Dose	Est._Prob. Expected Observed	Size	Residual
0.0000	0.0000	0.000	0.000	15	-0.005
52.5000	0.9474	18.000 18.000	19	-0.000
Chi^2 = 0.00	d.f. = 1	P-value = 0.9956
47
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FINAL
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Benchmark Dose Computation
Specified effect =	0.1
Risk Type =	Extra risk
Confidence level =	0.95
BMD =	1.8786
BMDL =	1.07041
BMDU =	3.21519
Taken together, (1.07041, 3.21519) is a 90	% two-sided confidence
interval for the BMD
Multistage Cancer Slope Factor =	0.0934223
48	4-Chloro-2-Methylaniline

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FINAL
9-30-2010
Multistage Cancer Model with 0.95 Confidence Level
—
4)
tJ
£
<
c
O
0.8
0.6
0.4
Multistage Cancer
Linear extrapolation
0.2
BMDL BMD
10
15	20
close
25
30
35
40
12:18 02/16 2010
Figure C.3. Multistage Cancer BMD Model for Male Vascular Tumor Incidence
(Weisburger et al., 1978)
Text Output for Multistage Cancer BMD Model for Male Vascular
Tumor Incidence Data (Weisburger et al., 1978)
Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)
Input Data File: C:\2\Weisburger_1978a_18mo_vasctumor_M_MultiCanc_l.(d)
Gnuplot Plotting File:
C:\2\Weisburger_1978a_18mo_vasctumor_M_MultiCanc_l.pit
Thu Feb 18 17:11:47 2010
TableB4 vascular tumor incidence male
The form of the probability function is:
P[response] = background + (1-background)*[1-EXP(
-betal*dose/sl-beta2*dose/s2) ]
The parameter betas are restricted to be positive
49
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FINAL
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Dependent variable = DichPerc
Independent variable = Dose
Total number of observations = 3
Total number of records with missing values = 0
Total number of parameters in model = 3
Total number of specified parameters = 0
Degree of polynomial = 2
Maximum number of iterations = 250
Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008
Default Initial Parameter Values
Background =	0.122308
Beta (1) = 0.0266452
Beta(2) =	0
Asymptotic Correlation Matrix of Parameter Estimates
( *** The model parameter(s) -Background -Beta(2)
have been estimated at a boundary point, or have been specified by
the user,
and do not appear in the correlation matrix )
Beta(1)
Beta (1)	1
Parameter Estimates
95.0% Wald Confidence
Interval
Variable	Estimate	Std. Err. Lower Conf. Limit Upper Conf.
Limit
Background	0	* * *
Beta(1)	0.0338098	* * *
Beta(2)	0	* * *
* - Indicates that this value is not calculated.
Analysis of Deviance Table
Model
Full model
Fitted model
Reduced model
Log(likelihood)
-26.4092
-27.2885
-37.2817
Param's
3
1
1
Deviance Test d.f.
1.75876
21.745
P-value
0. 415
<.0001
AIC:
56.5771
Goodness of Fit
Scaled
Dose	Est._Prob. Expected Observed	Size	Residual
0.0000	0.0000	0.000	0.000	14	0.000
50
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FINAL
9-30-2010
19.7000	0.4863	9.725 12.000	20
39.4000	0.7361	14.722 13.000	20
Chi^2 = 1.80	d.f. = 2	P-value = 0.4069
Benchmark Dose Computation
Specified effect =	0.1
Risk Type =	Extra risk
Confidence level =	0.95
BMD =	3.11627
BMDL =	2.2 4215
BMDU =	5.75997
Taken together, (2.24215, 5.75997) is a 90	% two-sided confidence
interval for the BMD
Multistage Cancer Slope Factor =	0.0446001
1. 018
-0.873
51
4-Chloro-2-Methylaniline

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BMDL
FINAL
9-30-2010
Multistage Cancer Model with 0.95 Confidence Level
0	5	10	15	20
dose
13:25 08/16 2010
Figure C.4. Multistage Cancer BMD Model for Male Vascular Tumor Incidence Data
without the High-Dose Data (Weisburger et al., 1978)
Multistage Cancer
Linear extrapolation
Text Output for Multistage Cancer BMD Model for Male Vascular Tumor Incidence Data
without the High-Dose Data (Weisburger et al., 1978)
Multistage Cancer Model. (Version: 1.9; Date: 05/26/2010)
Input Data File: C:/USEPA/BMDS21/Data/msc_4C2M_Weisburgerl978_M_Mscl-
BMR10.(d)
Gnuplot Plotting File: C:/USEPA/BMDS2l/Data/msc_4C2M_Weisburgerl978_M_Mscl-
BMR10.pit
Mon Aug 16 13:25:40 2010
BMDS Model Run
The form of the probability function is:
P[response] = background + (1-background)*[1-EXP(
-betal*dose/sl) ]
The parameter betas are restricted to be positive
52
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FINAL
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Dependent variable = Incidence
Independent variable = Dose
Total number of observations = 2
Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1
Maximum number of iterations = 250
Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008
Default Initial Parameter Values
Background =	0
Beta(1) = 0.0465122
Asymptotic Correlation Matrix of Parameter Estimates
( *** The model parameter(s) -Background
have been estimated at a boundary point, or have been specified by
the user,
and do not appear in the correlation matrix )
Beta(1)
Beta (1)	1
Parameter Estimates
95.0% Wald Confidence
Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf.
Limit
Background	0	*	*	*
Beta(1)	0.0465122	*	*	*
* - Indicates that this value is not calculated.
Model
Full model
Fitted model
Reduced model
Analysis of Deviance Table
#
Log(likelihood)
-13.4602
-13.4602
-22.0744
Deviance Test d.f.
Param's
2
1 3. 55271e-015
1	17.2284
P-value
<.0001
AIC:
28.9205
Goodness of Fit
Scaled
Dose	Est._Prob. Expected Observed	Size	Residual
0.0000	0.0000	0.000	0.000	14	0.000
19.7000	0.6000	12.000 12.000	20	0.000
53
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FINAL
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Chi^2 = 0.00	d.f. = 1	P-value = 1.0000
Benchmark Dose Computation
Specified effect =	0.1
Risk Type =	Extra risk
Confidence level =	0.95
BMD =	2.2 6522
BMDL =	1.43027
BMDU =	3.84714
Taken together, (1.43027, 3.84714) is a 90	% two-sided confidence
interval for the BMD
Multistage Cancer Slope Factor =	0.069917
54	4-Chloro-2-Methylaniline

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FINAL
9-30-2010
Multistage Cancer Model with 0.95 Confidence Level
1
Multistage Cancer
Linear extrapolation
0.8
0.6
0.4
0.2
0
BMDL
BMD
50	100	150	200	250	300	350	400
close
12:15 02/16 2010
Figure C.5. Multistage Cancer BMD Model for Male Hemangiosarcoma or
Hemangioma Tumor Incidence Data (NCI, 1979)
Text Output for Multistage Cancer BMD Model for Male Hemangiosarcoma or
Hemangioma Tumor Incidence Data (NCI, 1979)
Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)
Input Data File: C:\2\NCI_1979c_99wk_sarc_ang_M_MultiCanc_l.(d)
Gnuplot Plotting File: C:\2\NCI_1979c_99wk_sarc_ang_M_MultiCanc_l.plt
Tue Feb 16 12:15:48 2010
TableB2_all_sites_hemangiosarcoma_or_hemangioma_male_mouse
The form of the probability function is:
P[response] = background + (1-background)*[1-EXP(
-betal*dose/sl-beta2*dose/s2) ]
The parameter betas are restricted to be positive
Dependent variable = DichPerc
Independent variable = Dose
55
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FINAL
9-30-2010
Total number of observations = 3
Total number of records with missing values = 0
Total number of parameters in model = 3
Total number of specified parameters = 0
Degree of polynomial = 2
Maximum number of iterations = 250
Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008
Default Initial Parameter Values
Background =	0
Beta(1) = 0.000275628
Beta(2) = 1.04013e-005
Asymptotic Correlation Matrix of Parameter Estimates
( *** The model parameter(s) -Background
have been estimated at a boundary point, or have been specified by
the user,
and do not appear in the correlation matrix )
Beta(1)	Beta (2)
Beta (1)	1	-0.93
Beta (2)	-0.93	1
Parameter Estimates
Interval
Variable
Limit
Background
Beta(1)
Beta(2)
Estimate
0. 000275585
1.04015e-005
Std. Err.
95.0% Wald Confidence
Lower Conf. Limit Upper Conf.
Indicates that this value is not calculated.
Analysis of Deviance Table
Model
Full model
Fitted model
Reduced model
Log(likelihood)
-41.9159
-41.9159
-80.3385
# Param's Deviance	Test d.f.	P-value
3
2 4.27222e-009	1	0.9999
1 76.8452	2	<.0001
AIC:
87.8318
Goodness of Fit
Scaled
Dose	Est._Prob. Expected Observed	Size	Residual
0.0000	0.0000	0.000	0.000	20	-0.000
56
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FINAL
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98.4000	0.1200	6.000	6.000	50
393.0000	0.8200	41.000 41.000	50
Chi^2 =0.00	d.f. = 1	P-value = 0.9999
Benchmark Dose Computation
Specified effect =	0.1
Risk Type =	Extra risk
Confidence level =	0.95
BMD =	8 8.2 652
BMDL =	50.8704
BMDU =	110.309
Taken together, (50.8704, 110.309) is a 90	% two-sided confidence
interval for the BMD
Multistage Cancer Slope Factor = 0.00196578
0. 000
-0.000
57
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FINAL
9-30-2010
BMDL
Multistage Cancer Model with 0.95 Confidence Level
Multistage Cancer
Linear extrapolation
0	20	40	60	80	100	120
dose
09:51 08/12 2010
Figure C.6. Multistage Cancer BMD Model for Female Hemangiosarcoma or
Hemangioma Tumor Incidence Data (NCI, 1979)
Text Output for Multistage Cancer BMD Model for Female Hemangiosarcoma or
Hemangioma Tumor Incidence Data (NCI, 1979)
Multistage Cancer Model. (Version: 1.9; Date: 05/26/2010)
Input Data File: C:/USEPA/BMDS2l/Data/msc_4C2M_NCI1979_F_Msc2-BMR10.(d)
Gnuplot Plotting File: C:/USEPA/BMDS21/Data/msc_4C2M_NCI1979_F_Msc2-
BMR10.pit
Thu Aug 12 09:51:22 2010
BMDS Model Run
The form of the probability function is:
P[response] = background + (1-background)*[1-EXP(
-betal*dose/sl-beta2*dose/s2) ]
The parameter betas are restricted to be positive
Dependent variable = Incidence
Independent variable = Dose
58	4-Chloro-2-Methylaniline

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FINAL
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Total number of observations = 3
Total number of records with missing values = 0
Total number of parameters in model = 3
Total number of specified parameters = 0
Degree of polynomial = 2
Maximum number of iterations = 250
Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008
Default Initial Parameter Values
Background =	0.5 99716
Beta(1) = 0.00675779
Beta(2) =	0
Asymptotic Correlation Matrix of Parameter Estimates
( *** The model parameter(s) -Beta(2)
have been estimated at a boundary point, or have been specified by
the user,
and do not appear in the correlation matrix )
Background	Beta(l)
Background	1	-0.8
Beta (1)	-0.8	1
Parameter Estimates
Interval
Variable
Limit
Background
Beta(1)
Beta(2)
Estimate
0.466639
0.0109191
0
Std. Err.
95.0% Wald Confidence
Lower Conf. Limit Upper Conf.
Indicates that this value is not calculated.
Analysis of Deviance Table
Model
Full model
Fitted model
Reduced model
AIC:
Log(likelihood)
-46.3551
-64.8787
-69.601
133.757
# Param's	Deviance	Test d.f.
3
2	37.0472	1
1	46.4917	2
P-value
1.1530338e-009
<.0001
Goodness of Fit
Dose	Est._Prob. Expected Observed	Size
0.0000	0.4666	8.399	1.000	18
Scaled
Residual
-3.496
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32.8000	0.6272
131.0000	0.8724
Chi^2 = 31.42
d.f. = 1
30.733 44.000
43.621 39.000
P-value = 0.0000
49
50
3. 920
-1.959
Benchmark Dose Computation
Specified effect
Risk Type
Confidence level
BMD
BMDL
BMDU
0.1
Extra risk
0. 95
9.64917
5.75827
22.3152
Taken together, (5.75827, 22.3152) is a 90
interval for the BMD
two-sided confidence
Multistage Cancer Slope Factor =
0.0173663
60
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FINAL
9-30-2010
Multistage Cancer Model with 0.95 Confidence Level
Multistage Cancer
Linear extrapolation
1
0.8
0.6
0.4
0.2
0
BMDL
BMD
0
5
10
15
20
25
30
dose
11:13 08/12 2010
Figure C.7. Multistage Cancer BMD Model for Female Hemangiosarcoma or
Hemangioma Tumor Incidence Data without the High-Dose Data (NCI, 1979)
Text Output for Multistage Cancer BMD Model for Female Hemangiosarcoma or
Hemangioma Tumor Incidence Data without the High-Dose Data (NCI, 1979)
Multistage Cancer Model. (Version: 1.9; Date: 05/26/2010)
Input Data File: C:/USEPA/BMDS2l/Data/msc_4C2M_NCI1979_F_Mscl-BMR10.(d)
Gnuplot Plotting File: C:/USEPA/BMDS21/Data/msc_4C2M_NCI1979_F_Mscl-
BMR10.pit
Thu Aug 12 11:13:00 2010
BMDS Model Run
The form of the probability function is:
P[response] = background + (1-background)*[1-EXP(
-betal*doseAl) ]
The parameter betas are restricted to be positive
61
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FINAL
9-30-2010
Dependent variable = Incidence
Independent variable = Dose
Total number of observations = 2
Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1
Maximum number of iterations = 250
Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008
Default Initial Parameter Values
Background = 0.055555 6
Beta(1) = 0.0678422
Asymptotic Correlation Matrix of Parameter Estimates
Background	Beta(l)
Background	1	-0.4 8
Beta (1)	-0.48	1
Interval
Variable
Limit
Background
Beta(1)
Estimate
0.0555556
0.0678422
Parameter Estimates
95.0% Wald Confidence
Std. Err.	Lower Conf. Limit Upper Conf.
* - Indicates that this value is not calculated.
Warning: Likelihood for the fitted model larger than the Likelihood for the full
model.
Error in computing chi-sguare; returning 2
Model
Full model
Fitted model
Reduced model
Analysis of Deviance Table
Log(likelihood)
-20.0097
-20.0097
-42.4117
# Param's Deviance	Test d.f.	P-value
2
2 -7.10543e-015	0	NA
1 44.8039	1	<.0001
AIC:
44.0195
Dose
Est. Prob.
Goodness of Fit
Expected Observed	Size
Scaled
Residual
0.0000
32.8000
0.0556
0.8980
1.000
44.000
1.000
44.000
18
49
-0.000
0. 000
62
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FINAL
9-30-2010
Chi^2 =0.00	d.f. = 0	P-value =	NA
Benchmark Dose Computation
Specified effect =	0.1
Risk Type =	Extra risk
Confidence level =	0.95
BMD =	1.55302
BMDL =	1.137 69
BMDU =	2.14 97
Taken together, (1.13769, 2.1497 ) is a 90	% two-sided confidence
interval for the BMD
Multistage Cancer Slope Factor =	0.0878975
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APPENDIX D. REFERENCES
ACGIH (American Conference of Governmental Industrial Hygienists). (2009) 2009 TLVs and
BEIs: Threshold limit values for chemical substances and physical agents and biological
exposure indices. Cincinnati, OH: American Conference of Governmental Industrial Hygienists.
594528
ATSDR (Agency for Toxic Substances and Disease Registry). (2008) Toxicological profile
information sheet. Available online at http://www.atsdr.cdc. gov/toxpro2.html. Accessed on
2/25/2010. 595415
Bentley P; Bieri F; Muecke W; Waechter F; Staubli W. (1986) Species differences in the
toxicity of />chloro-o-toluidine to rats and mice: Covalent binding to hepatic macromolecules
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