United States
Environmental Protection
1=1 m m Agency
EPA/690/R-16/014F
Final
8-11-2016
Provisional Peer-Reviewed Toxicity Values for
TV, /V- Dim e th y 1 an i 1 i n e
(CASRN 121-69-7)
Superfund Health Risk Technical Support Center
National Center for Environmental Assessment
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, OH 45268
-------
AUTHORS, CONTRIBUTORS, AND REVIEWERS
CHEMICAL MANAGER
Elizabeth Owens, PhD
National Center for Environmental Assessment, Cincinnati, OH
DRAFT DOCUMENT PREPARED BY
SRC, Inc.
7502 Round Pond Road
North Syracuse, NY 13212
PRIMARY INTERNAL REVIEWER
Suryanarayana Vulimiri, PhD
National Center for Environmental Assessment, Research Triangle Park, NC
This document was externally peer reviewed under contract to:
Eastern Research Group, Inc.
110 Hartwell Avenue
Lexington, MA 02421-3136
Questions regarding the contents of this PPRTV assessment should 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).
li
A', A'-Di methyl aniline
-------
TABLE OF CONTENTS
COMMONLY USED ABBREVIATIONS AND ACRONYMS iv
BACKGROUND 1
DISCLAIMERS 1
QUESTIONS REGARDING PPRTVS 1
INTRODUCTION 2
REVIEW OF POTENTIALLY RELEVANT DATA (NONCANCER AND CANCER) 6
HUMAN STUDIES 11
Oral Exposures 11
Inhalation Exposures 11
ANIMAL STUDIES 11
Oral Exposures 11
Inhalation Exposures 18
OTHER DATA (SHORT-TERM TESTS, OTHER EXAMINATIONS) 20
Acute Toxicity 20
Other Routes 20
Genotoxicity 21
Metabolism/Toxicokinetic Studies 21
Mode of Action for Noncancer Effects 25
DERIVATION 01 PROVISIONAL VALUES 25
DERIVATION OF ORAL REFERENCE DOSES 26
Derivation of Subchronic Provisional Oral Reference Dose 26
Derivation of Chronic Provisional Oral Reference Dose 31
DERIVATION OF INHALATION REFERENCE CONCENTRATIONS 31
CANCER WEIGHT-OF-EVIDENCE DESCRIPTORS 31
MODE OF ACTION 34
DERIVATION OF PROVISIONAL CANCER POTENCY VALUES 34
Derivation of Provisional Oral Slope Factor 34
Derivation of Provisional Inhalation Unit Risk (p-IUR) 35
APPENDIX A. SCREENING PROVISIONAL VALUES 36
APPENDIX B. DATA TABLES 37
APPENDIX C. BENCHMARK DOSE MODELING RESULTS 46
APPENDIX D. REFERENCES 54
in
A', A'-Di methyl aniline
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COMMONLY USED ABBREVIATIONS AND ACRONYMS
a2u-g
alpha 2u-globulin
MN
micronuclei
ACGIH
American Conference of Governmental
MNPCE
micronucleated polychromatic
Industrial Hygienists
erythrocyte
AIC
Akaike's information criterion
MOA
mode of action
ALD
approximate lethal dosage
MTD
maximum tolerated dose
ALT
alanine aminotransferase
NAG
N-acetyl-P-D-glucosaminidase
AST
aspartate aminotransferase
NCEA
National Center for Environmental
atm
atmosphere
Assessment
ATSDR
Agency for Toxic Substances and
NCI
National Cancer Institute
Disease Registry
NOAEL
no-observed-adverse-effect level
BMD
benchmark dose
NTP
National Toxicology Program
BMDL
benchmark dose lower confidence limit
NZW
New Zealand White (rabbit breed)
BMDS
Benchmark Dose Software
OCT
ornithine carbamoyl transferase
BMR
benchmark response
ORD
Office of Research and Development
BUN
blood urea nitrogen
PBPK
physiologically based pharmacokinetic
BW
body weight
PCNA
proliferating cell nuclear antigen
CA
chromosomal aberration
PND
postnatal day
CAS
Chemical Abstracts Service
POD
point of departure
CASRN
Chemical Abstracts Service Registry
PODadj
duration-adjusted POD
Number
QSAR
quantitative structure-activity
CBI
covalent binding index
relationship
CHO
Chinese hamster ovary (cell line cells)
RBC
red blood cell
CL
confidence limit
RDS
replicative DNA synthesis
CNS
central nervous system
RfC
inhalation reference concentration
CPN
chronic progressive nephropathy
RfD
oral reference dose
CYP450
cytochrome P450
RGDR
regional gas dose ratio
DAF
dosimetric adjustment factor
RNA
ribonucleic acid
DEN
diethylnitrosamine
SAR
structure activity relationship
DMSO
dimethylsulfoxide
SCE
sister chromatid exchange
DNA
deoxyribonucleic acid
SD
standard deviation
EPA
Environmental Protection Agency
SDH
sorbitol dehydrogenase
FDA
Food and Drug Administration
SE
standard error
FEVi
forced expiratory volume of 1 second
SGOT
glutamic oxaloacetic transaminase, also
GD
gestation day
known as AST
GDH
glutamate dehydrogenase
SGPT
glutamic pyruvic transaminase, also
GGT
y-glutamyl transferase
known as ALT
GSH
glutathione
SSD
systemic scleroderma
GST
glutathione-S-transferase
TCA
trichloroacetic acid
Hb/g-A
animal blood-gas partition coefficient
TCE
trichloroethylene
Hb/g-H
human blood-gas partition coefficient
TWA
time-weighted average
HEC
human equivalent concentration
UF
uncertainty factor
HED
human equivalent dose
UFa
interspecies uncertainty factor
i.p.
intraperitoneal
UFh
intraspecies uncertainty factor
IRIS
Integrated Risk Information System
UFS
subchronic-to-chronic uncertainty factor
IVF
in vitro fertilization
UFd
database uncertainty factor
LC50
median lethal concentration
U.S.
United States of America
LD50
median lethal dose
WBC
white blood cell
LOAEL
lowest-observed-adverse-effect level
iv
A', A'-Di methyl aniline
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PROVISIONAL PEER-REVIEWED TOXICITY VALUES FOR
\. \ -1) I \ IK T11Y L A M LIN K (CASRN 121-69-7)
BACKGROUND
A Provisional Peer-Reviewed Toxicity Value (PPRTV) is defined as a toxicity value
derived for use in the Superfund Program. PPRTVs are derived after a review of the relevant
scientific literature using established Agency guidance on human health toxicity value
derivations. All PPRTV assessments receive internal review by a standing panel of National
Center for Environmental Assessment (NCEA) scientists and an independent external peer
review by three scientific experts.
The purpose of this document is to provide support for the hazard and dose-response
assessment pertaining to chronic and subchronic exposures to substances of concern, to present
the major conclusions reached in the hazard identification and derivation of the PPRTVs, and to
characterize the overall confidence in these conclusions and derived values. It is not intended to
be a comprehensive treatise on a given chemical or its toxicological nature.
The PPRTV review process provides needed toxicity values in a quick turnaround
timeframe while maintaining scientific quality. PPRTV assessments are updated approximately
on a 5-year cycle for new data or methodologies that might impact the toxicity values or
characterization of potential for adverse human health effects and are revised as appropriate. It is
important to use the PPRTV database (http://hhpprtv.ornl.gov) to obtain the current information
available. When a final Integrated Risk Information System (IRIS) assessment is made publicly
available on the Internet (http://www.epa.gov/iris). the respective PPRTVs are removed from the
database.
DISCLAIMERS
The PPRTV document provides toxicity values and information about the adverse effects
of a chemical and the evidence on which the value is based, including the strengths and
limitations of the data. All users are advised to review the information provided in this
document to ensure that the PPRTV used is appropriate for the types of exposures and
circumstances at the site in question and the risk management decision that would be supported
by this toxicity assessment.
Other U.S. Environmental Protection Agency (EPA) programs or external parties who
may choose to use PPRTVs are advised that Superfund resources will not generally be used to
respond to challenges, if any, of PPRTVs used in a context outside of the Superfund program.
This document has been reviewed in accordance with U.S. EPA policy and approved for
publication. Mention of trade names or commercial products does not constitute endorsement or
recommendation for use.
QUESTIONS REGARDING PPRTVS
Questions regarding the content of this PPRTV assessment should 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).
1
/V,/V-Dimethyl aniline
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INTRODUCTION
TV,TV-Dimethyl aniline, CASRN 121-69-7, is used as a chemical intermediate, notably in
the manufacture of dyes and vanillin (HSI)B, 2014). It is also used as a stabilizer, a catalytic
hardener for fiberglass, an activator for polyester, and an extraction solvent for refining
sulfur dioxide (HSI)B, 2014). TV,A;- Dimethy 1 ani 1 ine has been found as a synthetic impurity in
P-lactam antibiotics (IARC. 1993). It has also been detected in soil and lake and river waters
near industrial sources (IARC. 1993). TV, A;- Dimethy 1 ani 1 ine is regulated under Sections 8(a) and
8(d) of the Toxic Substances Control Act (TSCA) (40 CFR 712.30 and 716.20 [7/1/99]). It is
also listed as a hazardous air pollutant (HAP) under the Clean Air Act as amended in 1990
(CAA, 1990). TV, A;-Di methyl aniline may also be referred to as TV.W-dimethylbenzeneamine,
(dimethylamino)benzene, A', A'-di methylaminobenzene, dimethylaniline, dimethylphenylamine,
and TV, A;-di methyl phenyl amine (I ARC. 1993; U.S. EPA. 1987).
TV,TV-Dimethylaniline is liquid at room temperature. Its low melting point (2.5°C)
suggests that it may solidify at colder ambient temperatures. The estimated Henry's law constant
of the neutral form of TV, TV-di m eth y 1 an i 1 i n e indicates moderate volatilization from moist soil and
water surfaces. Based on the moderate vapor pressure, the neutral form of TV,TV-dimethylaniline
is not expected to volatize from dry soils, but if released to the air, A', A'-di methyl ani 1 i ne would
remain in the vapor phase (HSI)B. 2014). TV, A;-Di methyl aniline is expected to exist partially as a
cation in the environment: the pKa value of its conjugate acid is 5.15. The cationic form of
TV, A;-di methyl aniline is not expected to volatilize from either water or soil (HSDB. 2014).
TV, TV-Dim ethyl aniline's ability to leach from soil to groundwater is dependent on local conditions.
In areas with high amounts of organic matter, leaching of A' A-di m eth yl an i 1 i n e may be inhibited
due to the high reactivity of the aromatic amine group; the protonated form of
TV, A;-di methyl aniline is expected to bind strongly to soil surfaces (HSDB. 2014). In other areas,
/V,/V-dimethylaniline deposited on soil is likely to leach to groundwater or undergo runoff after a
rain event, due to its moderate water solubility and relatively low soil absorption coefficient. As
a result, removal of A', A'-di methyl ani line from soil by leaching with water will likely compete
with volatilization, depending on the local conditions. The empirical formula for
TV,TV-dimethyl aniline is CsHnN (see Figure 1). Some physicochemical properties of
TV,TV-dimethyl aniline are shown in Table 1.
Figure 1. TV,TV-Dimethylaniline Structure
2
TV,TV-Dimethyl aniline
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Table 1. Physicochemical Properties of jV,jV-Dimethylaniline (CASRN 121-69-7)
Property (unit)
Value
Physical state
Pale yellow, oily liquid3
Boiling point (°C)
193.54a
Melting point (°C)
2.503
Density (g/cm3)
0.9563
Vapor pressure (mm Hg at 25 °C)
0.703
pH (unitless)
6.46 for a 1% aqueous solution3
pKa (at 25°C)
5.15 for conjugate acid3
Solubility in water (g/L at 25°C)
1.453
Octanol-water partition constant (log Kow)
2.3 la
Henry's law constant (atm-m3/mol at 25°C)
5.68 x 10 " (estimated)13
Soil adsorption coefficient (Koc) (mL/g)
79 (estimated)13
Relative vapor density (air =1)
4.173
Molecular weight (g/mol)
121.183
•'HSDB (2014).
bU.S. EPA (2012c).
EPA's Integrated Risk Information System (IRIS) has developed a chronic oral reference
dose (RfD) value for N, A;-di methyl aniline (U.S. EPA. 1987). A summary of this value and other
available toxicity values for iV,iV-dimethylaniline from EPA and other agencies/organizations is
provided in Table 2.
3
TV,TV-Dimethyl aniline
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Table 2. Summary of Available Toxicity Values for
AyV-Dimethylaniline (CASRN 121-69-7)
Source
(parameter)ab
Value (applicability)
Notes
Reference
Noncancer
IRIS (RfC)
NV
NA
U.S. EPA (2016)
IRIS (RfD)
2 x 10 3 mg/kg-d
Based on splenomegaly, increased
splenic hemosiderosis and
hematopoiesis in mice.
U.S. EPA (1987)
HEAST (sRfD)
2 x 10 2 mg/kg-d
Based on effects on the spleen in mice.
U.S. EPA (2011a)
DWSHA
NV
NA
U.S. EPA (2012a)
ATSDR
NV
NA
ATSDR (2016)
WHO
NV
NA
WHO (2016)
Cal/EPA
NV
NA
Cal/EPA (2014);
Cal/EPA (2016a):
Cal/EPA (2016b)
OSHA (PEL)
TWA 5 ppm (25 mg/m3);
[skin]
The "[skin]" designation indicates the
potential for dermal absorption.
OSHA (2006);
OSHA (2011)
NIOSH (REL)
TWA 5 ppm (25 mg/m3);
STEL 10 ppm (50 mg/m3);
[skin]
The "[skin]" designation indicates the
potential for dermal absorption.
NIOSH (2015)
ACGIH (TLV)
TWA 5 ppm (25 mg/m3)
STEL 10 ppm (50 mg/m3);
[skin] notation
Based on potential for
methemoglobinemia, anoxia, and
resultant neurotoxicity due to structural
similarity to aniline.
ACGIH (2015)
ACGIH (BEI for
methemoglobin
inducers)
Methemoglobin in blood:
1.5% of hemoglobin
Sampling time: during or end of shift.
ACGIH (2006):
ACGIH (2015)
Cancer
IRIS
NV
NA
U.S. EPA (2016)
HEAST
NV
NA
U.S. EPA (2011a)
DWSHA
NV
NA
U.S. EPA (2012a)
NTP
NV
NA
NTP (2014)
I ARC (WOE)
Group 3—not classifiable as
to its carcinogenicity to
humans
Based on limited evidence of
carcinogenicity in one study in mice and
in one study in rats by gavage.
I ARC (1993)
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N,TV-Dimethyl aniline
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Table 2. Summary of Available Toxicity Values for
AyV-Dimethylaniline (CASRN 121-69-7)
Source
(parameter)ab
Value (applicability)
Notes
Reference
Cal/EPA
NV
NA
Cal/EPA (20 ID:
Cal/EPA (2016a):
Cal/EPA (2016b)
ACGIH (WOE)
A4—not classifiable as a
human carcinogen
Based on equivocal oncogenic data
from 2-yr gavage studies with rats and
mice.
ACGIH (2001);
ACGIH (2015)
aSources: ACGIH = American Conference of Governmental Industrial Hygienists; ATSDR = Agency for Toxic
Substances and Disease Registry; Cal/EPA = California Environmental Protection Agency; DWSHA = Drinking
Water Standards and Health Advisories; HEAST = Health Effects Assessment Summary Tables;
IARC = International Agency for Research on Cancer; IRIS = Integrated Risk Information System;
NIOSH = National Institute for Occupational Safety and Health; NTP = National Toxicology Program;
OSHA = Occupational Safety and Health Administration; WHO = World Health Organization.
Parameters: BEI = biological exposure indices; PEL = permissible exposure level; REL = recommended exposure
level; RfC = inhalation reference concentration; RfD = oral reference dose; sRfD = reference dose for subchronic
oral exposure; TLV = threshold limit value; WOE = weight of evidence.
NA = not applicable; NV = no value; STEL = short-term exposure limit; TWA = time-weighted average.
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Literature searches were conducted on sources published from 1900 through March 2016
for studies relevant to the derivation of provisional toxicity values for iV,iV-dimethylaniline
(CASRN 121-69-7). The following databases were searched by chemical name, synonyms, or
CASRN: ACGIH, ANEUPL, AT SDR, BIOSIS, Cal/EPA, CCRIS, CDAT, ChemlDplus, CIS,
CRISP, DART, EMIC, EPIDEM, ETICBACK, FEDRIP, GENE-TOX, HAPAB, HERO, HMTC,
HSDB, I ARC, INCHEM IPCS, IP A, ITER, IUCLID, LactMed, NIOSH, NTIS, NTP, OSHA,
OPP/RED, PESTAB, PPBIB, PPRTV, PubMed (toxicology subset), RISKLINE, RTECS,
TOXLINE, TRI, U.S. EPA IRIS, U.S. EPA HEAST, U.S. EPA HEEP, U.S. EPA OW, and
U.S. EPA TSCATS/TSCATS2. The following databases were searched for toxicity values or
exposure limits: ACGIH, AT SDR, Cal EPA, U.S. EPA IRIS, U.S. EPA HEAST, U.S. EPA
HEEP, U.S. EPA OW, U.S. EPA TSCATS/TSCATS2, NIOSH, NTP, OSHA, and RTECS.
REVIEW OF POTENTIALLY RELEVANT DATA
(NONCANCER AND CANCER)
Tables 3 A and 3B provide an overview of the relevant databases for iV,iV-dimethylaniline
and include all potentially relevant repeat-dose, short-term-, subchronic-, and chronic-duration
studies. Principal studies are identified. The phrases, "statistical significance" and "significant,"
used throughout the document, indicate ap-walue of < 0.05 unless otherwise noted.
Chronic-duration oral studies are described below; however, a chronic provisional reference dose
(p-RfD) is not derived due to the availability of a chronic oral RfD value for A', A'-dimethyl aniline
on EPA's IRIS database (see Table 2).
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A', A'-Dimethyl aniline
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Table 3A. Summary of Potentially Relevant Noncancer Data for AyV-Dimethylaniline (CASRN 121-69-7)
Category3
Number of
Male/Female, Strain,
Species, Study Type,
Study Duration
Dosimetryb
Critical Effects
NOAELb
BMDL/
BMCLb
LOAELb
Reference
(comments)
Notes0
Human
1. Oral (mg/kg-d)
ND
2. Inhalation (mg/m3)
ND
Animal
1. Oral (mg/kg-d)b
Short-term
5 M/5 F, F344/N rat,
gavage (corn oil), 14 d
0, 94, 188, 375,
750, 1,500
ADD: 0, 94, 188,
375, 750, 1,500
Splenomegaly
94
NDr
188
FEL:750
NTP (1989)
PR
Short-term
5 M/5 F, B6C3Fi
mouse, gavage (corn
oil), 15 d
0, 94, 188, 375,
750, 1,500
ADD: 0, 94, 188,
375, 750, 1,500
Splenomegaly and splenic
pathology (extramedullary
hematopoiesis and
hemosiderosis)
188
NDr
375
FEL:750
NTP (1989)
PR
Short-term
5 M/0 F, rat (strain not
specified), gavage,
11/15 d (undiluted) or
13/17 d (corn oil)
0, 100, 1,000
ADD: 0,
73.3 (11/15 d),
1,000 (2 d)
Mortality (1,000 mg/kg-d),
abnormal RBC morphology,
increased spleen weight,
splenic congestion
ND
NDr
73.3
FEL:
1,000
Eastman Kodak (1992); Eastman
Kodak (1995)
NPR
0, 10, 100
ADD: 0, 7.7,
76.5 (13/17 d)
Abnormal RBC morphology,
increased spleen weight,
splenic congestion
7.7
NDr
76.5
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N,TV-Dimethyl aniline
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Table 3A. Summary of Potentially Relevant Noncancer Data for AyV-Dimethylaniline (CASRN 121-69-7)
Category3
Number of
Male/Female, Strain,
Species, Study Type,
Study Duration
Dosimetryb
Critical Effects
NOAELb
BMDL/
BMCLb
LOAELb
Reference
(comments)
Notes0
Short-term
0 M/10 F, CD-I mouse,
gavage (corn oil), 8 d
0, 365, 725, 1,455,
2,910, 5,815
ADD: 0, 365, 725,
1,455, 2,910, 5,815
High mortality, clinical signs
(lethargy, prostration,
unkempt appearance)
ND
NDr
FEL: 365
Piccirillo et al. (1983)
NPR
Subchronic
10 M/10 F; F344/N rat,
gavage (corn oil),
5 d/wk, 13 wk
0, 31.25, 62.5,125,
250,500
ADD: 0,22.32,
44.6, 89.3,179,
357
Splenic pathology
(extramedullar
hematopoiesis and
hemosiderosis)
ND
NDr
22.32
Abdo et al. (1990): NTP (1989)
PR, PS
(Hematology, clinical
chemistry, urinalysis, and
organ weights not examined or
reported)
Renal pathology
(hemosiderosis)
ND
3.1d
22.32
Subchronic
10 M/10 F, B6C3Fi
mouse, gavage (corn
oil), 5 d/wk, 13 wk
0,31.25,62.5, 125,
250, 500
ADD: 0, 22.32,
44.6, 89.3, 179,
357
Splenomegaly
(>22.32 mg/kg-d) and
splenic pathology
(extramedullary
hematopoiesis and
hemosiderosis;
>44.6 mg/kg-d)
ND
5.48
(based on
increased
spleen
hematopoiesis
in males)
22.32
Abdo et al. (1990): NTP (1989)
(Hematology, clinical chemistry,
urinalysis, and organ weights not
examined or reported; incidence
of all groups and severity of
splenomegaly not reported)
PR, IRIS
Chronic
50 M/50 F; F344/N rat,
gavage (corn oil),
5 d/wk, 103 wk
0, 3, 30
ADD: 0, 2, 21
Hemosiderosis of the spleen
(increased severity)
ND
NDr
2
NTP (1989)
(Hematology, clinical chemistry,
urinalysis, and organ weights not
examined or reported)
PR
Chronic
50 M/50 F, B6C3Fi
mouse, gavage (corn
oil), 5 d/wk, 103 wk
0, 15, 30
ADD: 0, 11,21
No significant effects
21
NDr
ND
NTP (1989)
(Hematology, clinical chemistry,
urinalysis, and organ weights not
examined or reported)
PR
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Table 3A. Summary of Potentially Relevant Noncancer Data for AyV-Dimethylaniline (CASRN 121-69-7)
Category3
Number of
Male/Female, Strain,
Species, Study Type,
Study Duration
Dosimetryb
Critical Effects
NOAELb
BMDL/
BMCLb
LOAELb
Reference
(comments)
Notes0
Developmental
0 M/50 F, CD-I
pregnant mouse, gavage
(corn oil), GDs 6-13
0, 365
ADD: 0, 365
No significant effects on
evaluated maternal or
developmental endpoints
(number of litters, litter size,
offspring survival and body
weight)
365
NDr
ND
Hardin et al. (1987): Piccirillo et
al. (19831
(Fetal development not
examined)
PR
2. Inhalation (mg/m3)b
Subchronic
Unspecified M/0 F,
albino rat, unspecified
inhalation, 24 hr/d,
100 d
0, 0.0055, 0.3
HEC: 0, 0.0055,
0.3
Changes in several
hematology and clinical
chemistry parameters and
histopathological lesions in
the liver, spleen, brain, and
lungs
0.0055
NDr
0.3
Markosvan (1969)
(data from this study cannot be
considered reliable due to
inadequate reporting)
PR
(Translated
from
Russian
journal)
'Category (treatment/exposure duration, unless otherwise noted): short-term = repeated exposure for >24 hours <30 days (U.S. EPA. 20021: long-term (subchronic) = repeated
exposure for >30 days <10% lifespan for humans (more than 30 days up to approximately 90 days in typically used laboratory animal species) (U.S. EPA. 20021:
chronic = repeated exposure for >10% lifespan for humans (more than approximately 90 days to 2 years in typically used laboratory animal species) (U.S. EPA. 20021.
bDosimetry: values are presented as adjusted daily dose (ADD, in mg/kg-day) for oral noncancer effects and as human equivalent concentration (HEC, in mg/m3) for inhalation
noncancer effects. The HEC was calculated using the equation for extra respiratory effects from a Category 3 gas (U.S. EPA. 19941: HECexresp = continuous concentration
in mg/m3 x ratio of animal:human blood-gas partition coefficients (default value of 1 applied).
°Notes: IRIS = used by IRIS; NPR = not peer reviewed; PR = peer reviewed; PS = principal study.
dBenchmark dose modeling was performed with four data points (minus two highest doses).
ADD = adjusted daily dose; BMCL = benchmark concentration lower confidence limit; BMDL = benchmark dose lower confidence limit; F = female(s); FEL = frank effect level;
GD = gestation day; HEC = human equivalent concentration; LOAEL = lowest-observed-adverse-effect level; M = male(s); ND = no data; NDr = not determined;
NOAEL = no-observed-adverse-effect level; RBC = red blood cell.
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Table 3B. Summary of Potentially Relevant Cancer Data for jV,jV-Dimethylaniline (CASRN 121-69-7)
Category
Number of Male/Female,
Strain, Species, Study
Type, Study Duration
Dosimetry3
Critical Effects
BMDL/BMCL3
Reference
(comments)
Notesb
Human
1. Oral (mg/kg-d)
ND
2. Inhalation (mg/m3)
ND
Animal
1. Oral (mg/kg-d)a
Carcinogenicity
50 M/50 F; F344/N rat,
gavage, 5 d/wk, 103 wk
0,3,30
HED: 0,0.5,5.0
Combined incidence of sarcoma and
osteosarcoma in males (considered "some
evidence of carcinogenicity" by NTP)
3.7
NTP (1989)
PR, PS
Carcinogenicity
50 M/50 F, B6C3Fi
mouse, gavage, 5 d/wk,
103 wk
0, 15, 30
HED: 0, 1.5, 3.0
Squamous cell papillomas of the forestomach
in females (considered "equivocal evidence
of carcinogenicity" by NTP)
NDr
NTP (1989)
PR
2. Inhalation (mg/m3)
ND
"Dosimetry: the units for oral exposures are expressed as human equivalent dose (HED) (mg/kg-day). HED = animal dose as ADD (mg/kg-day) x default dosimetric
adjustment factor (DAF) calculated as (BWt, BWh)1/4 [0.24 for rats and 0.14 for mice (U.S. EPA. 2011bYl.
bNotes: PR = peer reviewed; PS = principal study.
ADD = adjusted daily dose; BMCL = benchmark concentration lower confidence limit; BMDL = benchmark dose lower confidence limit; F = female(s); HED = human
equivalent dose; M = male(s); ND = no data; NDr = not determined; NTP = National Toxicology Program.
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HUMAN STUDIES
Oral Exposures
No studies examining possible associations between health effects in humans and oral
exposure to A', A-di methyl aniline have been identified.
Inhalation Exposures
No studies examining possible associations between health effects in humans and
repeated inhalation exposure to A', A-di methyl aniline have been identified.
ANIMAL STUDIES
Oral Exposures
The effects of oral exposure of animals to iV,/V-dimethylaniline were evaluated in five
short-term-duration studies (Dow Chemical Co. 1995; Eastman Kodak. 1995. 1992; NTP. 1989;
Piccirillo et ai. 1983). two subchronic-duration studies (Abdo et ai. 1990; NTP. 1989). two
chronic-duration studies (NTP. 1989). and a single developmental toxicity study (Hardin et ai.
1987; Piccirillo et ai. 1983).
Short-Term-Duration Studies
NTP (1989)
Male and female Fischer 344/N rats and B6C3Fi mice (five/sex/group) were
administered doses of 0 (vehicle control), 94, 188, 375, 750, or 1,500 mg/kg-day
/V,/V-dimethylaniline (>98% pure) via gavage in corn oil for 14 consecutive days (rats) or
15 consecutive days (mice). The animals were observed twice daily and weighed on Days 1, 7,
14 (rats), and 15 (mice). Food and water consumption were not reported. Hematology, clinical
chemistry, and urinalysis data were not collected in this study. All animals were necropsied;
however, organ weights were not measured. Histologic examinations were performed on three
male and three female rats from the 94- and 375-mg/kg-day dose groups and on three male and
three female mice from the 375-mg/kg-day dose group. Tissues examined include adrenal
glands, brain, colon, duodenum, esophagus, gallbladder (mice only), heart, ileum, jejunum,
kidneys, larynx, liver, lungs and bronchi, salivary glands, testes or ovaries/uterus, skin, spleen,
thymus, and trachea.
All male and female rats that received the 1,500-mg/kg-day dose died during the study, as
did four out of five male rats and all five female rats at the 750-mg/kg-day dose level
(see Table B-l). As shown in Table B-l, terminal body weights of male rats given 375 and
750 mg/kg-day were 15% and, in the one survivor at 750 mg/kg-day, 47% lower than controls,
respectively. Terminal body-weight measurements for female rats were within 10% of control
values for all dose groups with survivors (i.e., <375 mg/kg-day) (see Table B-l). Clinical signs
observed in the 750- and 1,500-mg/kg-day dose groups of male and female rats included
cyanosis, lethargy, fine body tremors, diarrhea, and red ocular or nasal discharge. A statistically
significant increase in the incidence of splenomegaly was seen in rats given doses
>188 mg/kg-day (genders combined; see Table B-l). Extramedullary hematopoiesis and
increased hemosiderin were observed in the spleens of all three male and three female rats
examined at the 375-mg/kg-day dose level (and presumably none of those examined at the
94-mg/kg-day dose level, although that was not explicitly stated). No-observed-adverse-effect
level (NOAEL) and lowest-observed-adverse-effect level (LOAEL) values of 94 and
188 mg/kg-day, respectively, are identified for this study based on the significant increase in the
incidence of splenomegaly in rats (combined genders).
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In the mouse study, mortality was observed in all male and female mice that received 750
or 1,500 mg/kg-day of A', A-di methyl aniline (see Table B-2). One male mouse died after
receiving 188 mg/kg-day, but this death was determined by the study authors not to be
compound related. Terminal body weights of treated male and female mice were within 10% of
control values for all dose groups with survivors (i.e., <375 mg/kg-day) (see Table B-2).
Clinical signs observed in male and female mice included lethargy, excess salivation, and
tremors (dose levels were not specified, but the signs were reported as "compound-related").
Splenomegaly was seen in one of five male mice at 188 mg/kg-day, and two of five male and
three of five female mice at 375 mg/kg-day (see Table B-2). Congestion and increased
extramedullary hematopoiesis or hemosiderin were seen in the spleens of all three male and three
female mice examined at the 375-mg/kg-day dose (no histopathology was examined in the
188-mg/kg-day group). NOAEL and LOAEL values of 188 and 375 mg/kg-day, respectively,
are identified based on splenomegaly and splenic pathology in male and female mice.
Eastman Kodak (1992); Eastman Kodak (1995)
Male rats (five/group; strain not specified) were administered A' A-di methyl ani 1 i ne (purity
not reported) via gavage (undiluted) at 100 or 1,000 mg/kg-day for up to 15 days
(2-11 exposures total). Although a group of five control rats (administered water) was
reportedly used, no data for these animals were provided. Mortality and clinical signs of toxicity
were monitored regularly. Body weights were recorded (presumably prior to study initiation and
at study termination). Food consumption was measured (time points not specified). Hematology
(red blood cell [RBC] and total and differential white blood cell [WBC] counts, hematocrit [Hct],
and hemoglobin [Hb] concentration) and clinical chemistry evaluations (aspartate
aminotransferase [AST], alanine aminotransferase [ALT], alkaline phosphatase [ALP], lactate
dehydrogenase [LDH], blood urea nitrogen [BUN], and glucose) were performed. The animals
were subjected to gross pathology examinations. Liver, kidney, and/or spleen weights were
recorded. Various tissues (not specified, but likely tissues warranting further examination based
on gross observations and including the liver, kidney, spleen, and thymus) were examined
microscopically. Quantitative data were not provided; effects were classified by the direction of
change (no change, increased, or decreased) and/or severity (slight, moderate, or great).
The rats administered two daily doses of 1,000 mg/kg-day died or were sacrificed
moribund within 8 hours of the second treatment. Clinical signs of toxicity included loss of
coordination in hindquarters, depression, dark eyes, pale skin, and otherwise poor general
appearance. Rats treated at 1,000 mg/kg-day also showed decreased food intake (graded as
"great") and decreased body weights (graded as "slight") compared to controls. The one animal
subjected to clinical pathology analyses showed hematological effects (slight reductions in Hct,
Hb concentration, and RBC count, and abnormal RBC morphology with substantially increased
total WBC and granulocyte counts) and clinical chemistry effects (moderately increased AST
activity, and greatly increased serum glucose and BUN). In the animals dosed at
1,000 mg/kg-day and sacrificed moribund (three rats), absolute liver and kidney weights were
unaffected by treatment; the small increases in relative organ weights were likely an artifact of
decreased body weight. Gross pathology revealed brownish-colored blood in the internal organs,
and enlarged, dark spleens. Microscopic examinations showed effects in the liver (hypertrophy
of hepatic nuclei, in 1/3 animals), kidney (bilateral tubular nephrosis, in 2/3 animals), spleen
(congestion with lymphoid follicular hyperplasia, in 3/3 animals), and thymus (necrotic
thymiditis, in 2/3 animals).
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Rats dosed at 100 mg/kg-day received 11 treatments over 15 days. Gavage doses of
100 mg/kg-day were converted to average daily doses of 73.3 mg/kg-day by multiplying the
administered gavage dose by doses/days (11/15). No mortality or clinical signs of toxicity were
reported. Food intake was not affected, and body weights were decreased (graded as "slight") in
treated rats relative to controls. Clinical pathology changes in 73.3-mg/kg-day rats were limited
to abnormal RBC morphology (polychromasia, poikilocytosis, anisocytosis, and macrocytosis)
and an increase in LDH activity (graded as "slight"). There were no biologically or statistically
significant treatment-related effects on absolute or relative liver and kidney weights; however,
absolute and relative spleen weights were increased (graded as "great"). Gross and microscopic
pathology findings were also confined to the spleen. Spleens appeared dark and enlarged;
microscopic evaluations revealed congestion (possibly hemorrhagic in nature). The results
suggest that the duration-adjusted lowest-observed-adverse-effect-level (LOAELadj) is
73.3 mg/kg-day for increased spleen weights and corresponding hematological (abnormal RBC
morphology) and histopathological (splenic congestion) changes.
In an effort to determine a no-effect level, the same endpoints were evaluated in male rats
(five/group) administered /V,/V-dimethylaniline at 10 or 100 mg/kg-day via gavage in corn oil
over 17 days (13 total doses). Gavage doses of 10 and 100 mg/kg-day were converted to average
daily doses of 7.7 and 76.5 mg/kg-day by multiplying the administered gavage dose by
doses/days (13/17). Although a group of control rats was reportedly used, no data for these
animals were provided. Mortality, body weights, and food consumption were unaffected by
treatment. There were no significant, treatment-related effects in rats treated at 7.7 mg/kg-day.
Effects observed at 76.5 mg/kg-day included those seen in the preceding study (abnormal RBC
morphology [polychromasia, anisocytosis, poikilocytosis, and Howell-Jolly bodies], increased
absolute and relative spleen weight, and gross and microscopic spleen changes [enlarged, dark
spleens in 2/5 animals and congestion with lymphoid hyperplasia in 4/5 animals]). Changes in
other hematological parameters (increased WBCs, granulocytes, mean corpuscular volume
[MCV] and Hb; decreased RBC count, Hct, and Hb concentration) were also observed, but were
classified as slight. Whitish tissue on the peritoneum, pericardium, and lung (one lobe),
observed grossly in both groups of treated rats, was determined microscopically to be lipoidal
connective tissue. These data, while limited and not peer reviewed, provide evidence for a
LOAELadj of 76.5 mg/kg-day based on hematological effects (including abnormal RBC
morphology), increased spleen weight, and spleen histopathology (congestion with lymphoid
hyperplasia). The duration-adjusted no-observed-adverse-effect level (NOAELadj) is
7.7 mg/kg-day.
Dow Chemical Co (1995)
Rats (n = 9 in total; strain not specified) were administered N, A'-dimethylani 1 ine (purity
not reported) orally (presumably daily via gavage) at 0.1, 1, 10, 100, 500, or 5,000 mg/kg until
death or until 20 doses were given; sacrifices were performed 9-10 days following dosing in the
surviving animals. The number of rats per treatment group was 1,2, 1, 2, 2, and 1 in the 0.1-, 1-,
10-, 100-, 500-, and 5,000-mg/kg groups, respectively. No control group was used. The liver,
kidney(s), spleen, adrenal gland, and pancreas from all rats were examined microscopically
(other tissues, if examined, were not specified). Hematological analyses (endpoints not
specified) were performed on three rats administered 1,10, and 100 mg/kg after 10 and 20 doses.
The study results were described qualitatively; raw data (other than the presence or absence of
microscopic lesions with some indication of severity) were not provided. For the purposes of
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this review, the severity ratings of (±, +, ++, and +++, given in the study report) were assumed to
correspond to minimal, mild or slight, moderate, and marked, respectively.
The incidence of mortality was 0/1, 1/2, 0/1, 0/2, 1/2, and 1/1 at 0.1, 1, 10, 100, 500, and
5,000 mg/kg, respectively. Although the study summary indicates that hematological changes
occurred at doses as low as 10 mg/kg, significant changes in blood parameters were only
mentioned by the study authors at 100 mg/kg (moderate anemia and slight neutrophilic
leukocytosis after 10 doses; anemia in the absence of leukocytosis after 20 doses).
Histopathological changes at 1 mg/kg were confined to the spleen, and consisted of minimal to
mild congestion and deposition of blood pigments. Higher doses of A' A-di m eth y 1 an i 1 i n e induced
splenic congestion accompanied by hemosiderosis of the spleen (ranging from minimal to
marked at >10 mg/kg), tubular nephritis (minimal to moderate at 100 and 500 mg/kg), and
hepatic degeneration (minimal to moderate at 500 and 5,000 mg/kg). There were no
histopathological changes in the adrenal gland or pancreas at any dose. Owing to the poor
quality of the study (based on few numbers of animals per dose group, lack of controls, and
inadequate data reporting), no NOAEL or LOAEL can be identified.
Piccirillo et al. (1983)
In a dose-finding study, female virgin CD-I mice (10/group) were given 0 (vehicle
control), 365, 725, 1,455, 2,910, or 5,815 mg/kg-day iV,/V-dimethylaniline by gavage in corn oil
for 8 consecutive days (purity assumed by authors to be 100%). Mice were observed for clinical
signs of toxicity twice daily during the treatment period and for 8 days following treatment.
Body weights and physical examinations were recorded on the first and last days of treatment
and on the fourth and eighth day following treatment. Dead mice were necropsied to determine
whether the cause of death was gavage error or was compound related. Mortality was observed
in all treatment groups, with 100% mortality seen by Day 4 of treatment at doses
>1,455 mg/kg-day. Doses of 365 and 725 mg/kg-day produced 40 and 70% mortality,
respectively, with one death in the lowest-dose group attributed to gavage error. Clinical signs
of toxicity included lethargy, tremors, prostration, ataxia, and/or unkempt appearance. Surviving
animals from the lowest dose group exhibited lethargy, prostration, and/or unkempt appearance
intermittently throughout the treatment period. Body weights for these animals were not
significantly different from control values. A frank effect level (FEL) of 365 mg/kg-day is
identified based on chemical-related mortality observed in 3/9 mice from the lowest-dose group.
Subchronic-Duration Studies
Abdo et al (1990); NTP (1989)
Male and female Fischer 344/N rats and B6C3Fi mice (10/sex/group) were exposed to
doses of 0 (vehicle control), 31.25, 62.5, 125, 250, or 500 mg/kg-day /V,/V-dimethylaniline
(98.2%) purity) via gavage in corn oil once daily for 5 consecutive days/week for 13 weeks.
These gavage doses were converted to adjusted daily doses (ADDs) of 22.32, 44.6, 89.3, 179,
and 357 mg/kg-day by multiplying the administered gavage dose by (5/7) days/week. Animals
were observed twice daily for morbidity and mortality. Clinical signs and body weights were
recorded weekly. Doses were adjusted weekly for changes in body weights. The study did not
report food or water consumption by rats or mice during the 13-week study period. Hematology,
clinical chemistry, and urinalysis data were not collected in this study. All animals (those that
died during the study and those that survived to study termination) were necropsied and gross
lesions were recorded, but organ weights were not measured. Complete histopathological
examinations (of >30 tissues) were performed and lesions were graded by severity (i.e., minimal,
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mild, moderate, marked, severe). Selected tissues (not specified) were stained to confirm the
presence of hemosiderin.
Mortality during the study was observed in one male rat (at 357 mg/kg-day) and three
female rats (one each at 44.6, 89.3, and 179 mg/kg-day) (see Table B-3). All of these deaths
were attributed to gavage error, as confirmed by the presence of corn oil in the lung. Clinical
signs of toxicity were decreased motor activity (noted in all individual rats at doses
>89.3 mg/kg-day), excessive salivation (doses not reported), and cyanosis (noted in all individual
rats at doses >179-mg/kg-day). Body weights of male rats exposed to 179 or 357 mg/kg-day
were lower than controls throughout the study period. There was a statistically significant
decrease in terminal body weights of male rats exposed to 89.3, 179, and 357 mg/kg-day from
controls by 7, 15, and 27%, respectively (see Table B-3). Female rats exposed to doses
>89.3 mg/kg-day also exhibited decreased terminal body weight; however, the observed
decreases were <10% of control values (3—5%; see Table B-3). The only gross pathology
change noted in this study was splenomegaly, which was observed in all treatment groups of rats
(incidence not reported).
Histopathological changes were found in the testis of male rats, and the spleen, liver,
kidney, and bone marrow of male and female rats. The incidence and/or severity of lesions
increased with increasing dose level. As shown in Table B-4, the severity of extramedullary
hematopoiesis and hemosiderosis in the spleen increased with increasing dose in male and
female rats. These effects occurred in 90-100% of treated animals in each dose group.
Macrophages filled with yellow-brown granular pigment that tested positive for iron
(hemosiderin) were prominent in the spleen of male and female rats at all doses (in contrast with
controls). Hemosiderosis was also observed in the kidneys, liver, and testes; however, this effect
generally occurred with lower incidence and severity and at higher doses, compared to the
spleen, where 100% incidence was seen at the lowest dose (see Table B-4). The severity of
splenic hematopoiesis and hemosiderosis was mild at the lowest dose and increased to marked
and severe, respectively, at the highest dose. The cortical tubular epithelial cells in the kidneys
contained abundant hemosiderin at doses >44.6 mg/kg-day in male rats and >22.32 mg/kg-day in
female rats. In the liver, significant numbers of Kupffer cells were enlarged and exhibited
hemosiderin in male rats treated with >89.3 mg/kg-day A' A-dimethylani 1 ine and in female rats
receiving doses >44.6 mg/kg-day. These cells tended to be localized in the centrilobular region
of the liver. Hemosiderin-filled macrophages were present in the testes of male rats treated with
179 or 357 mg/kg-day iV,/V-dimethylaniline, intermingled with interstitial cells between
seminiferous tubules. Finally, significantly increased incidence of bone marrow hyperplasia was
observed in male and female rats at doses of >89.3 mg/kg-day, compared with controls. A
LOAEL of 22.32 mg/kg-day is identified based on histopathological effects in the spleen of male
and female rats and the kidney of female rats. A NOAEL is not identified because effects
occurred at the lowest dose level in treated rats.
In the mouse study, two male mice died at 22.32 mg/kg-day, three died at
44.6 mg/kg-day, one died at 179 mg/kg-day, and one died in the control group (see Table B-5).
One female mouse died at 44.6 mg/kg-day. All of these deaths were attributed to gavage error
based on the presence of corn oil in the lung. Clinical signs of toxicity include blanching (paling
or whitening of skin) and decreased motor activity, which was observed in all treatment groups
of male mice and in female mice at >89.3 mg/kg-day. No other clinical signs of toxicity were
reported. Male mice given A'A-di methyl ani line had lower body weights than controls,
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beginning at 4 weeks of treatment, and terminal body weights were reduced by 9-12% in each
treatment group. Body weight was not significantly affected by treatment in female mice
(see Table B-5). The only gross pathology change noted in this study was splenomegaly, which
was observed in all mice receiving doses >89.3 mg/kg-day iV,/V-dimethylaniline. Splenomegaly
was also observed in 4/10 and 7/10 male mice and 4/10 and 8/10 female mice treated with 22.32
and 44.6 mg/kg-day, respectively. Severity of the splenomegaly, organ-weight measures, or
incidence of splenomegaly in control mice was not reported.
Histopathologic changes were found in the spleen, liver, and kidney of male and female
mice, as noted in Table B-6. As with rats, the incidence and/or severity of lesions increased with
increasing dose and effects in the spleen occurred at lower doses than similar effects seen in the
liver and kidney. Extramedullary hematopoiesis in the spleen increased statistically significantly
in male and female mice compared with control animals at doses >44.6 mg/kg-day.
Macrophages filled with hemosiderin in the spleen were increased in both sexes of mice at doses
>44.6 mg/kg-day compared to controls. In the liver of male and female mice treated with
>89.3 mg/kg-day N, A'-dimethylani 1 ine, significant numbers of Kupffer cells were enlarged and
exhibited hemosiderin. Extramedullary hematopoiesis was observed in the liver of male and
female mice at the highest-dose level only (357 mg/kg-day). The cortical tubular epithelial cells
in the kidneys contained abundant hemosiderin at doses >179 mg/kg-day in female mice, while
hemosiderosis occurred only at the highest dose in male mice (357 mg/kg-day). Based on
splenomegaly in male and female mice, a LOAEL of 22.32 mg/kg-day is identified. A NOAEL
is not identified because effects occurred at the lowest dose in treated mice.
Chronic-Duration/Carcinogenicity studies
NTP (1989)
Groups of male and female F344/N rats or B6C3Fi mice (50/sex/group) were
administered A'A-di methyl ani line (98.2% purity) via gavage in corn oil at 0, 3, or 30 mg/kg-day
(rats) or at 0, 15, or 30 mg/kg-day (mice), 5 days/week for 103 weeks (NTP. 1989). Gavage
doses in rats of 3 or 30 mg/kg-day were converted to ADDs of 2 or 21 mg/kg-day by multiplying
the administered gavage dose by days/week (5/7). Gavage doses in mice of 15 or 30 mg/kg-day
were converted to ADDs of 11 or 21 mg/kg-day by multiplying the administered gavage dose by
days/week (5/7). Animals were monitored twice daily for mortality and clinical signs of toxicity.
Body weights were recorded at study initiation, weekly for 12 weeks, and once per month
thereafter until study termination. No clinical pathology (hematology or clinical chemistry) or
urinalysis evaluations were performed. All animals were subjected to necropsy, and complete
histopathological examinations (of >30 tissues) were conducted for rats in the control and
high-dose groups (and in low-dose animals that died early or with grossly visible lesions). Gross
lesions and additional tissues were examined in all low-dose rats including spleen and testes
(male rats), kidney, liver, and spleen (female rats), adrenal glands (mice), and liver and spleen
(female mice).
The survival of treated rats was not significantly lower than controls; survival in
high-dose females was significantly higher than controls after 99 weeks due to a high number of
control females killed moribund (survival at study termination [i.e., 104 weeks] was 21/50,
32/50, and 36/50 in control, low-dose, and high-dose female rats, respectively). No explanation
was given for the morbidity and mortality observed in the female control rats. No clinical signs
of toxicity attributed to treatment were observed. The body weights of rats from all dose groups
(including controls) were similar (varied by <8% at all measured time points). Nonneoplastic
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findings were confined to the spleen and liver (see Table B-7). The incidence of some splenic
lesions (hemosiderosis and hematopoiesis) was high in all groups of rats (including controls).
However, the severity of these lesions was significantly increased in treated rats of both sexes
relative to controls (hemosiderosis at >2 mg/kg-day and hematopoiesis at 21 mg/kg-day); the
severity of these lesions ranged from minimal to marked (marked lesions [hematopoiesis]
reported in female rats at >2 mg/kg-day). The incidence of other lesions was significantly
increased at 21 mg/kg-day in rats of one sex only (fibrosis and fatty metamorphosis of the spleen
in males and chronic focal inflammation of the liver in females). Data with respect to the
severity of these effects were not provided by the study authors. A LOAEL of 2 mg/kg-day is
identified for increased severity of splenic hemosiderosis in male and female rats. No NOAEL is
determined.
Neoplastic findings in male and female rats are shown in Table B-8. The only
statistically significant finding was a positive trend for splenic tumors with increasing dose in
male rats (based on analyses for sarcoma or combined sarcoma or osteosarcoma, p = 0.01 by
Cochran-Armitage trend test). The incidence of spleen sarcoma (3/50) or incidence of combined
spleen sarcoma or osteosarcoma (4/50) in high-dose males increased compared to the concurrent
control group (0/49) (p = 0.06 by incidental tumor test and Fisher's exact test), as well as equaled
or exceeded the greatest historical incidence of spleen sarcoma in control male rats given corn oil
gavage (1/45), and the overall historical incidence for National Toxicology Program (NTP)
studies (3/2,081) (no osteosarcomas have been observed) (NTP, 1989). The sarcomas had varied
morphology, with characteristics of hemangiosarcomas and osteosarcomas. The NTP concluded
that there was "some evidence of carcinogenic activity" of A', A'-di methyl aniline in male rats
based on the occurrence of sarcomas or osteosarcomas (combined) of the spleen. Splenic tumors
were not increased in treated female rats, and the NTP concluded that there was "no evidence of
carcinogenic activity" of A', A'-di methyl aniline in female rats. NTP (1989) also concluded that
the carcinogenic responses may have been greater had larger doses been administered to the rats.
The survival of treated mice was not significantly different from controls. No clinical
signs of toxicity attributed to treatment were observed. The body weights of treated mice were
similar to controls (>94% of control values at all measured time points). Nonneoplastic findings
were confined to the forestomach (focal epithelial hyperplasia) and pituitary gland
(chromophobe cell hyperplasia) of female mice; while the incidence of these lesions was slightly
increased relative to controls, statistical significance was not achieved (see Table B-9). There
were no significant nonneoplastic histopathological findings in male mice. These data identify a
NOAEL of 21 mg/kg-day in male and female mice. No LOAEL is determined.
No significantly increased incidences of tumors were observed in male mice. Female
mice showed a significantly increased incidence of squamous cell papillomas of the forestomach
at 21 mg/kg-day compared to concurrent controls (8/50 vs. 2150, p = 0.04 by incidental tumor
test); a statistically significant trend for this tumor type with increasing dose was also seen
(p = 0.02 by Cochran-Armitage trend test) (see Table B-9). The tumor incidence in high-dose
female mice was higher than the overall NTP control incidence of 32/2,047 in corn oil gavage
studies, but did not differ markedly from the greatest historical control incidence in female mice
in previous studies (8/50 [16%] vs. 5/44 [11%]). No squamous cell carcinomas were identified
in high-dose female mice, leading the authors to suggest that the forestomach papillomas might
not be progressive. The NTP concluded there was "equivocal evidence for carcinogenic
activity" of /V,/V-dimethylaniline in female mice based on increased incidence of squamous cell
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papillomas of the forestomach, and "no evidence of carcinogenic activity" in male mice. NTP
(1989) also concluded that the carcinogenic responses may have been greater had larger doses
been administered to the mice.
Reproductive/Developmental Studies
Hardin et al. (1987); Piccirillo et al. (1983)
Based on the results of the dose-finding study described above (Piccirillo et al. 1983).
time-mated pregnant CD-I mice (50/group) were given 0 or 365 mg/kg-day A'A-di methyl aniline
(purity not reported) by gavage in corn oil on Gestation Days (GDs) 6-13 (Hardin et al, 1987;
Piccirillo et al. 1983). Mice were permitted to deliver pups, and the total litter weight and
number of live born pups were recorded. Offspring were returned to their dams until Postnatal
Day (PND) 3 when the number of live pups was counted and the litter weight and dam weights
were measured. Females that failed to deliver by GD 22 were sacrificed and uteri were
examined grossly. If there was no gross evidence of a failed pregnancy, the uteri were treated
with 10% ammonium or sodium sulfide to reveal implantation sites.
Three deaths were recorded among treated dams, but this did not represent a significant
increase over controls (0 deaths). Administration of A'A-di methyl aniline did not significantly
affect maternal-weight gain or the number of viable litters produced. Similarly, no significant
effects were seen on the number of live newborns per litter, offspring survival, birth weight, or
weight gain per pup. The NOAEL for this study is 365 mg/kg-day. A LOAEL value is not
identified because a single dose group was employed and no effects were observed.
Inhalation Exposures
Subchronic-Duration Studies
Markosyan (1969)
In a peer-reviewed study translated to English from Russian, male albino rats (number
per group not specified) were exposed to A', A'-di methyl aniline at reported concentrations of 0,
0.0055, or 0.3 mg/m3, 24 hours/day, 7 days/week for 100 days and were permitted to recover
postexposure (time not specified). No descriptions of the methods used in the experiment
(i.e., atmosphere generation, exposure methodology, and/or monitoring data) were provided.
The endpoints evaluated included hematological (total RBC, total and differential WBC, and
reticulocyte counts; Hb, methemoglobin [MetHb] [by modified cyanohemoglobin method], Hct,
mean corpuscular hemoglobin [MCH], mean corpuscular hemoglobin concentration [MCHC],
mean corpuscular volume, color index, and Heinz bodies in RBCs) and clinical chemistry
parameters (total protein, albumin, globulins, and albumin: globulin ratio; SH (sulfhydryl)
groups, and pyruvic acid), other specific tests of liver function (bromsulphalein test,
concentration of pyruvic acid in the liver, and urinary excretion of coproporphyrins), and
rheobase and chronaxie of antagonistic muscles (descriptors of the strength-duration curve for a
muscle stimulus). Based on the text and on the time points shown for data presented graphically,
at least some of these endpoints (including hematology parameters) were evaluated every
2 weeks. At study termination, the concentration of ascorbic acid (a form of Vitamin C) in the
liver, adrenals, spleen, and kidney was measured; relative organ weights (presumably of the
same organs) were recorded, and histopathology of "several" organs and tissues (not further
specified, but including the brain, spleen, liver, adrenal, and lungs) was performed. Quantitative
data pertaining to endpoints other than reticulocyte count and the bromsulphalein test were not
shown in the study report.
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Mortality, if it occurred, was not reported. No significant effects were reported in rats
exposed at 0 or 0.0055 mg/m3. All of the effects described are for rats exposed to
TV,TV-dimethyl aniline at 0.3 mg/m3. Exposure induced anemia as evidenced by decreased Hb
levels and RBC counts (data not shown). Anemia was characterized as microcytic and
normachromic (likely indicated by decreased MCV with no change in MCH), and moderate
poikolocytosis (presence of abnormally shaped RBCs) was noted (data not provided). The level
of MetHb (hemoglobin with a compromised ability to bind oxygen) was significantly increased
in rats exposed at 0.3 mg/m3 from 6 weeks (time of maximum decrease in Hb) until study
termination. Heinz bodies (RBCs containing denatured Hb) were detected during the second half
of the exposure period. Reticulocyte counts were significantly increased, particularly at 6 and
12 weeks (when Hb and RBC counts were decreased and/or MetHb concentration was
increased). Based on data presented graphically in the study report, reticulocytes were
significantly increased in rats exposed at 0.3 mg/m3 by about 23% at 6 weeks and 10% at
12 weeks, relative to controls. Total WBC count was decreased in rats exposed at 0.3 mg/m3;
although lymphocytes were increased, segmented neutrophil and eosinophil counts were
decreased (data not shown). Clinical pathology results revealed reductions in total protein,
albumin, and (3- and y-globulins; the albumin:globulin ratio was increased (data not shown). The
level of SH groups in the serum was also decreased, which the study authors suggested might
reflect decreased proteinogenic function of the liver. In other specific tests of liver function,
exposed rats showed only a slight change with respect to the excretion of bromsulphalein. The
retention coefficient for exposed rats was not significantly different from controls. However, the
urinary excretion of coproporphyrins was increased, and there was a trend for increasing pyruvic
acid in the serum (data not shown).
Evaluations of muscle function in rats exposed to TV,TV-dimethylaniline at 0.3 mg/m3
showed disturbances to the normal ratios of rheobases and chronaxias (changes not further
explained), particularly in the first half of the experiment. At study termination, ascorbic acid
(antioxidant) levels tended to be increased in the spleen and decreased in the liver and adrenals
of exposed rats (data not shown). Relative spleen and adrenal weights were increased by about
20 and 40%, respectively. No data for absolute organ weights or relative organ weights of other
tissues were provided. Histopathology findings were reported for the liver, spleen, brain, and
lungs of exposed rats (no incidence or severity data were provided). Rats exposed at 0.3 mg/m3
showed a high concentration of hemosiderin in the spleen, hepatic trabeculae with cells
containing compact nuclei, cellular polymorphisms, moderate dilatation of sinusoids and central
veins, and hypertrophy of Kupffer cells in the liver, chromatolysis of the cortical neurons
accompanied by decreased tigroid substance and polar rearrangement of Nissl bodies in the
brain, and changes to the epithelial cells (marked proliferation, deformation, compact nuclei,
desquamation into the lumen) of the bronchial mucosa of the lungs. The study authors indicated
that the "majority" of affected endpoints normalized during the recovery period (no additional
information was provided). The data provided identify a lowest-observed-adverse-effect
concentration (LOAEC) of 0.3 mg/m3 and a no-observed-adverse-effect concentration (NOAEC)
of 0.0055 mg/m3 based on significant effects on hematology and clinical chemistry parameters
and histopathological findings in the liver, spleen, brain, and lungs. However, an independent
evaluation of the data from this study was not possible, due to inadequate reporting of the
methods and results. No details were provided regarding the test substance purity or the method
used to generate the chamber air concentrations, and measured concentrations were not reported
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for this study. The study results are presented primarily in a qualitative statement, with no
indication of the incidence of occurrence or the magnitude of any effect.
OTHER DATA (SHORT-TERM TESTS, OTHER EXAMINATIONS)
Acute Toxicity
Oral median lethal dose (LD50) values in rodents were 951-1,348 mg/kg (rats),
1,345-1,500 mg/kg (mice), and <2,400 mg/kg (guinea pigs) (Dow Chemical Co. 1995; Eastman
Kodak. 1995; Mellon Institute of Industrial Research. 1995; Eastman Kodak. 1992; NTP. 1989).
Clinical signs included weakness, rough coats, tremors, prostration, nasal discharge, and
cyanosis. Gross and microscopic examinations were not performed.
Median lethal concentration (LC50) values were not established in rats or guinea pigs at
nominal concentrations of 2,000-5,000 mg/m3 (DuPont Haskell Lab. 1995; Mellon Institute of
Industrial Research. 1995; DuPont. 1983a; Buffalo Color. 1982; FDRL. 1982a. b; Price et al.
1978). Measured aerosol concentrations, when provided, were substantially lower than nominal
concentrations (1,000-2,000 mg/m3) (Buffalo Color. 1982). Clinical signs of toxicity (such as
breathing changes and signs of irritation) were generally transient in nature; no significant gross
pathology findings were reported.
In rats (three/group; sex not specified) administered a single gavage dose of
/V,/V-dimethylaniline at 500 mg/kg and analyzed 2 and 4 hours after dosing, blood MetHb levels
were 34-42% compared to about 1% in controls (Eastman Chemical Company. 1995). No
additional details were provided. A' A - Di m ethyl an i 1 i ne produced methemoglobinemia in
two cats (one male/one female) given a dose of 50 mg/kg by gavage as an emulsion in
carboxymethyleel 1 ulose (BASF. 1996). The MetHb level was increased in blood by 2 hours after
dosing and was increased to 70-77% 4 and 6 hours postdosing. The blood MetHb level began to
decline 24 hours after exposure. Hb binding was measured 24 hours after gavage dosing with
70 mg/kg A'A-di methyl aniline in three female Wistar rats. The Hb binding index (HBI) for
TV, A'-dimethyl aniline was approximately half the HBI reported for aniline-HCl (Birner and
Neumann. 1988).
Blood from male CFE rats (two/group) administered 250 mg/kg TV,TV-dimethylaniline via
intramuscular injection was subsequently analyzed for MetHb formation (Mellon Institute of
Industrial Research. 1995). MetHb as the percentage of total Hb was about 4-10% 1 hour after
treatment and 10—12% 4 hours after treatment in A' A-dimethylani 1 ine-treated rats compared to
13-22% 1, 2, and 4 hours after treatment in positive controls (treated with aniline). No negative
control group was used. No further information was provided.
Other Routes
New Zealand white (NZW) rabbits (two/sex/group) administered A' A-di methyl ani 1 i ne
(undiluted; approximately 7 mg/kg) to the skin under occluded conditions for 24 hours and
evaluated immediately after exposure showed increased MetHb levels (4.6 times higher than
baseline levels); although some recovery occurred, levels remained 2.2 times higher than pretest
levels 5 days postexposure (Bio Dynamics. 1982). There were no significant effects on Hb, Hct,
or RBC counts. Rabbits (two/sex/group) administered 2 mL of the test substance at 0.03 or 6 g/L
(approximately 0.02 and 4 mg/kg) under the same conditions showed no significant changes in
hematological parameters.
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DuPont (1983b) reported that undiluted A', A;-di methyl aniline was moderately irritating to
the skin of albino guinea pigs (two males) following application of 0.1 g to shaved skin after 24
and 48 hours.
Genotoxicity
TV,TV-Dimethyl aniline has been tested in a number of in vitro and in vivo genotoxicity
assays (see Table 4). TV, TV-Di methyl aniline did not induce reverse mutations in Salmonella
typhimurium (Tanineher et ai. 1993; N I P. 1989; Mortelmans et ai. 1986; Mori et aL 1980).
Forward mutations were increased in mouse lymphoma L5 178 Y cells (N I P. 1989).
TV, TV-Dimethyl aniline induced sister chromatid exchanges (SCEs) and chromosomal aberrations
(CAs) in Chinese hamster ovary (CHO) cells in the presence of S9 mix (l.ovedav et al.. 1989).
In the absence of S9 mix, negative results were obtained for SCEs and only a weak positive
result was obtained for CAs at the highest dose tested. In addition, TV, TV-dim ethyl aniline
increased micronuclei in metabolically active Chinese hamster V79 cells (Tanineher et al..
1993). Deoxyribonucleic acid (DNA) repair was not induced in cultured rat hepatocytes
following exposure to TV, A;-di methyl aniline (Yoshimi et al.. 1988). In in vivo studies,
TV, TV-dimethyl aniline was weakly positive for DNA damage of liver nuclei in male BALB/c mice
and Sprague-Dawley (S-D) rats following intraperitoneal (i.p.) administration; however, this
compound did not produce DNA damage in liver nuclei assessed by the alkaline elution assay
following exposure by gavage (Tanineher et al. 1993).
Metabolism/Toxicokinetic Studies
TV,TV-Dimethyl aniline is readily absorbed through the skin but limited information is
available on the absorption through oral and inhalation routes (ACGIH. 2001). The metabolism
of TV,TV-dimethylaniline has been well studied in in vitro test systems from several species,
including adult and fetal human tissues [reviewed by NTP (1989); IARC (1993)1. The primary
metabolic reactions identified in vitro include TV-oxidation, catalyzed by flavin-containing
monooxygenases (Zieeler. 1980; Rane. 1974; Gold and Zieeler. 1973). as well as
TV-demethylation and ring hydroxylation, catalyzed by CYP450 enzymes (Macl)onald et al..
1989; Pandcv et al.. 1989; Hamill and Cooper, 1984; Gooderham and Gorrod, 1981; Hlavica and
Hulsmann. 1979; Devereux and Touts. 1974). TV-Demethylation may also be catalyzed by
peroxidative mechanisms mediated by human term placental lipoxygenase enzymes (Hover and
Kulkarni. 2000). Demethylation of the parent compound and the TV,TV-dimethylaniline TV-oxide
metabolite results in the formation ofTV-methylaniline and formaldehyde (Kitada et al.. 1974).
Aryl ring hydroxylation by CYP450 is a minor pathway resulting in formation of
TV,TV-dimethyl-4-aminophenol and its nonenzymatic decomposition product,
TV-methyl-4-aminophenol (Gooderham and Gorrod. 1981). The TV-methylaniline metabolite may
undergo further TV-demethylation to produce aniline followed by subsequent ring- and
TV-hydroxylation to produce 4-aminophenol and phenylhydroxylamine, respectively. The liver is
the primary site of TV,TV-dimethylaniline metabolism, but oxidative metabolism has also been
shown to occur in the rat and rabbit lung (Ohmiva and Mehendale. 1983).
TV,TV-Dimethyl aniline metabolism and urinary excretion were evaluated in mongrel dogs
following a single intravenous (i.v.) injection of 40 mg/kg (undiluted) (Kiese and Renner. 1974).
Urine was collected over a 48-hour period, and urinary metabolites were measured after
deconjugation with glucuronidase and sulfatase enzymes. Metabolites included TV-methylaniline,
2- and 4-aminophenol, TV-methyl-2-aminophenol, TV-methyl-4-aminophenol,
TV,TV-dimethyl-2-aminophenol, and TV,TV-dimethyl-4-aminophenol. TV,TV-dimethylaniline-TV-oxide
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was not detected in blood or urine. Aniline was found in the blood 2 hours after injection, but
not the urine. Subsequent metabolism of aniline results in the production of 2- and
4-aminophenol, which may be why aniline was not detected in urine. Fecal excretion was not
evaluated in any of the available studies.
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Table 4. Summary of AyV-Dimethylaniline (CASRN 121-69-7) Genotoxicity
Endpoint
Test System
Dose/
Concentration
Results
Without
Activation3
Results
With
Activation3
Comments
References
Genotoxicity studies in prokaryotic organisms
Mutation
Salmonella typhimurium
strains TA98, TA100
0-1 nmol
—
—
NA
Mori et al. (1980)
Mutation
S. typhimurium strains
TA98, TA100, TA1535,
TA1537
0,3, 10,33, 100,333,
1,000 ng/plate
Toxicity was observed at 1,000 |ig/plate.
NTP (1989);
Mortelmans et al.
(1986)
Mutation
S. typhimurium strains
TA97, TA98, TA100
0, 1,2.5,5, 10, 40, 70,
100 |ig/platc
—
—
Toxicity was observed at 100 |ig/platc.
Taiiinglier et al.
(1993)
Genotoxicity studies in mammalian cells—in vitro
Mutation
Mouse lymphoma L5178Y
cells
0, 200, 300, 400, 500,
600, 800 ng/mL (-S9)
0, 10, 20, 30, 40, 50,
60 ng/mL (+S9)
+
+
In the absence of metabolic activation,
statistically significant toxicity was
observed at concentrations producing a
positive response (400-600 ng/mL, 100%
lethality at 600 and 800 |ig/mL). In the
presence of metabolic activation, the
relative mutant fraction was increased at
concentrations >20 |ig/mL. Toxicity was
observed at concentrations of >50 ng/mL
in the presence of metabolic activation.
NTP (1989)
SCE
CHO cells
0, 30, 100, 300 ng/mL
(-S9)
0, 10, 30, 100, 101,
302, 1,010 ng/mL
(+S9)
+
The lowest concentration producing a
positive response in the presence of
metabolic activation was 30 |ig/mL.
Lovedav et al.
(1989);
NTP (1989)
Chromosome
aberrations
CHO cells
0, 83, 415, 830 ng/mL
(-S9)
0, 83,415, 505,755,
830, 1,010 ng/mL
(+S9)
±
+
Weak positive result in the absence of S9
was seen at the highest concentration only
(830 |ig/mL). Positive results occurred at
all concentrations (>83 ng/mL) in the
presence of S9.
Lovedav et al.
(1989);
NTP (1989)
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Table 4. Summary of AyV-Dimethylaniline (CASRN 121-69-7) Genotoxicity
Endpoint
Test System
Dose/
Concentration
Results
Without
Activation3
Results
With
Activation3
Comments
References
Micronucleus test
Chinese hamster lung cells
(V79)
0,0.3,0.9, 1.2 mM
+
NA
Metabolically active cell line. Positive
findings seen at concentrations >0.9 mM.
Mitotic index did not suggest significant
cytotoxicity at any concentration.
Tanineher et al.
(1993)
DNA repair
(unscheduled DNA
synthesis)
Cultured rat hepatocytes
0, 1, 10, 100, 1,000 \iM
NA
Metabolically active cells.
Yoshimi et al.
(1988)
Genotoxicity studies—in vivo
DNA damage/strand
breaks (alkaline
elution test)
Male BALB/c mouse
(number/groups not
specified); i.p. injection;
DNA damage assessed in
liver nuclei 2 or 24 hr after
treatment
0, 2, 4 mmol/kg (2 hr);
0, 2 mmol/kg (24 hr)
0, 242, 485 mg/kg
(2 hr); 0, 242 mg/kg
(24 hr)
±
±
Weak positive response at 4 mmol/kg for
2 hr and 2 mmol/kg at 24 hr.
Tanineher et al.
(1993)
DNA damage/strand
breaks (alkaline
elution test)
Male S-D rat
(number/groups not
specified); i.p. injection;
DNA damage assessed in
liver nuclei 2 or 24 hr after
treatment
0, 4, 8 mmol/kg (2 hr);
0, 4 mmol/kg (24 hr)
0, 485, 969 mg/kg
(2 hr); 0, 485 mg/kg
(24 hr)
±
±
Weak positive response at 4 and
8 mmol/kg for 2 hr. No change was
observed 24 hr after injection of
4 mmol/kg.
Tanineher et al.
(1993)
DNA damage/strand
breaks (alkaline
elution test)
Male S-D rat
(number/groups not
specified); gavage; DNA
damage assessed in liver
nuclei 6 and 24 hr after
treatment
0, 8 mmol/kg
0, 969 mg/kg
No statistically significant changes in
DNA elution rate.
Tanineher et al.
(1993)
'"+ = positive; ± = weaMy positive; - = negative.
CHO = Chinese hamster ovary; DNA = deoxyribonucleic acid; i.p. = intraperitoneal; NA = not applicable; SCE = sister chromatid exchange; S-D = Sprague-Dawley.
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Mode of Action for Noncancer Effects
Mechanistic studies described above (i.e., "Acute Toxicity" and "Other Routes" sections)
demonstrate methemoglobinemia and Hb binding following N,TV-dimethyl aniline treatment
(BASF. 1996; Eastman Chemical Company. 1995; Mellon Institute of Industrial Research. 1995;
Birner and Neumann. 1988; Bio Dynamics. 1982). Oxidation of the heme iron in Hb leading to
the production of MetHb may lead to the noncancer effects of A' A -di m ethy 1 ani 1 i ne
(e.g., splenomegaly and spleen histopathology). A similar hematological mechanism has been
proposed for aniline. Toxicokinetic studies demonstrate that aniline is a metabolite of
N,TV-dimethyl aniline, and both compounds have several common metabolites
(e.g., 4-aminophenol, phenylhydroxylamine). Mode-of-action (MOA) information pertaining to
the splenic toxicity of aniline was reviewed by Bus and Popp (1987). Possible key events
leading to the toxicity of aniline were suggested to include: (1) accumulation of the parent
compound or metabolites carried to the spleen by RBCs; (2) covalent binding to erythrocyte and
splenic macromolecules; and (3) deposition of erythrocyte debris resulting in hemosiderin
accumulation, vascular congestion, and hemorrhage. Other studies have suggested that the
splenotoxicity of aniline is due to oxidative stress and lipid peroxidation (Khan et al. 1998).
Some of these key events may also apply to the splenic toxicity of A'A'-di methyl aniline;
however, evidence to support these key events following exposure to A', A'-di methyl aniline is
limited. Hemosiderin accumulation was observed in rats exposed to A', A'-di methyl aniline for
13 weeks or 2 years (Abdo et al.. 1990; NTP. 1989). Extramedullar hematopoiesis was also
observed in these studies. A review that focused on this effect suggested that extramedullar
hematopoiesis may be related to specific changes in the stem cell microenvironment, including
bone marrow failure, myelostimulation, tissue inflammation, injury, and repair, and abnormal
cytokine production (Johns and Christopher, 2012). There are no mechanistic studies available
for TV,TV-dimethylaniline that evaluate these possible key events; thus, uncertainty remains on the
MOA leading to toxic effects in the spleen following A', A'-dimethy 1 ani 1 ine exposure.
DERIVATION OF PROVISIONAL VALUES
Tables 5 and 6 present summaries of noncancer and cancer references values,
respectively.
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Table 5. Summary of Noncancer Reference Values for
AyV-Dimethylaniline (CASRN 121-69-7)
Toxicity Type (units)
Species/Sex
Critical Effect
/>-Reference
Value
POD
Method
POD
(HED)
UFc
Principal
Study
Subchronic p-RfD
(mg/kg-d)
F344/N
Rat/M and F
Extramedullary
hematopoiesis and
hemosiderosis of
the spleen
2 x 1(T3
LOAEL
5.3
3,000
Abdo et al.
(1990);
NTP (1989)
Chronic p-RfD (mg/kg-d)
Oral RfD value is available on IRIS (U.S. EPA. 1987)
Subchronic p-RfC
(mg/m3)
NDr
Chronic p-RfC (mg/m3)
NDr
F = female(s); HED = human equivalent dose; IRIS = Integrated Risk Information System;
LOAEL = lowest-observed-adverse-effect level; M = male(s); NDr = not determined; POD = point of departure;
p-RfC = provisional reference concentration; p-RfD = provisional reference dose; UFc = composite uncertainty
factor.
Table 6. Summary of Cancer Reference Values for
AyV-Dimethylaniline (CASRN 121-69-7)
Toxicity Type (units)
Species/Sex
Tumor Type
Cancer Value
Principal Study
p-OSF (mg/kg-d) 1
Rat/male
Splenic sarcoma or osteosarcoma
2.7 x 10-2
NTP (1989)
p-IUR (mg/m3)-1
NDr
NDr = not determined; p-IUR = provisional inhalation unit risk; p-OSF = provisional oral slope factor.
DERIVATION OF ORAL REFERENCE DOSES
The database of oral studies in experimental animals includes five short-term-duration
studies (Dow Chemical Co, 1995; Eastman Kodak, 1995, 1992; NTP, 1989; Piccirillo et ai,
1983), two subchronic-duration studies (Abdo et ai, 1990; NTP, 1989), two chronic-duration
studies (NTP, 1989), and one developmental toxicity study (Hardin et aL 1987; Piccirillo et ai,
1983). A sub chronic p-RfD is derived based on the available studies.
A chronic p-RfD is not derived because there is an oral RfD value on EPA's IRIS
database (U.S. EPA, 1987).
Derivation of Subchronic Provisional Oral Reference Dose
The subchronic-duration study in adult rats exposed via gavage to A', A'-di methyl aniline is
considered the principal study for the derivation of the subchronic p-RfD (Abdo et ai, 1990;
NTP, 1989). The critical effects from this study include extramedullary hematopoiesis and
hemosiderosis of the spleen.
The subchronic studies conducted by Abdo et ai (1990) and NTP (1989) report
administration of A' A-dimethylani 1 ine by gavage to F344/N rats and B6C3Fi mice (10/sex/dose)
for 13 weeks. These studies are included in a peer-reviewed technical report conducted
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according to Good Laboratory Practice (GLP) standards. They are well-conducted studies with
adequate reporting and consideration for appropriate study design, methods, and conduct.
However, uncertainty remains due to the lack of comprehensive endpoint evaluation;
hematology, clinical chemistry, urinalysis, and organ-weight measurements were not performed
or reported. The short-term-duration gavage studies in rats and mice were not selected as
principal studies due to the brief exposure duration (8-15 days). A chronic-duration rat study
(N I P. 1989) demonstrated spleen effects at 10-fold lower doses than the subchronic-duration
study; however, this study was not selected as a principal study for the subchronic p-RfD
derivation due to the near-lifetime exposure duration (i.e., 103 weeks). No maternal or offspring
effects were observed in mice given 365 mg/kg-day /V,/V-dimethylaniline via gavage on
GDs 6-13 (Hardin et aL 1987; Piccirillo et aL 1983). This dose is higher than the dose
producing spleen effects in adults.
The subchronic-duration study in rats reported statistically significant increases in
extramedullar hematopoiesis in the spleen and hemosiderosis in the spleen and kidney
following administration of all treatment doses. Extramedullar hematopoiesis is the formation
and development of blood cells outside the medullary spaces of the bone marrow and in adult
animals indicates a molecular change in patterns of hematopoiesis to reactivation of embryonic
sites of hematopoiesis (e.g., spleen) (Johns and Christopher. 2012). An increase in hemosiderosis
is a result of abnormal tissue deposition of iron pigment. Both events may be related to aberrant
RBC destruction by intravascular hemolysis and increased erythrophagocytosis, where excessive
deposition of damaged RBCs may result in splenomegaly and associated tissue dysfunction.
A LOAELadj of 22.32 mg/kg-day is established based on histopathological lesions of the
spleen in rats with no NOAEL identified. A LOAELadj of 44.6 mg/kg-day and NOAELadj of
22.32 mg/kg-day were established in mice based on similar splenic lesions (see Table 7). The
increased hematopoiesis and hemosiderosis of the spleen and kidney occurred at lower doses
compared to liver and testes, and at lower doses than other observed effects, such as bone
marrow hyperplasia in rats (Abdo et aL 1990; N I P. 1989). The effects in the spleen were
observed at the lowest doses tested across short-term, subchronic, and chronic exposure
durations (see Table 3A).
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Table 7. Potential Subchronic PODs in Male and Female F344/N Rats and B6C3Fi Mice
Exposed to AyV-Dimethylaniline (CASRN 121-69-7) for 13 Weeks3
Endpoint
Sex
NOAELADjb
(mg/kg-d)
LOAELADjb
(mg/kg-d)
BMD
(mg/kg-d)
BMDLio
(mg/kg-d)
POD
(HED)c'd
(mg/kg-d)
Rats
Kidney hemosiderosis
F
ND
22.32
5.14
3.11e
0.75
Liver hemosiderosis
F
22.32
44.6
21.8
11.3
2.71
Bone marrow
hyperplasia
M
44.6
89.3
33.1
19.7
4.73
Liver hemosiderosis
M
44.6
89.3
33.1
19.7
4.73
Kidney hemosiderosis
M
22.32
44.6
38.0
21.6
5.18
Spleen hematopoiesis
M
ND
22.32
NA
NA
5.357
Spleen hemosiderosis
M
ND
22.32
NA
NA
5.357
Spleen hematopoiesis
F
ND
22.32
NA
NA
5.357
Spleen hemosiderosis
F
ND
22.32
NA
NA
5.357
Bone marrow
hyperplasia
F
44.6
89.3
No fit
No fit
10.7
Mice
Spleen hematopoiesis
M
22.32
44.6
18.0
5.48
0.767
Spleen hemosiderosis
M
44.6
89.3
23.8
12.5
1.75
Spleen hemosiderosis
F
22.32
44.6
36.5
21.4
3.00
Spleen hematopoiesis
F
22.32
44.6
36.5
21.4
3.00
Decreased terminal body
weight
M
ND
22.32f
No fit
No fit
3.125
Liver hemosiderosis
M
44.6
89.3
No fit
No fit
6.24
Liver hematopoiesis
M
179
357
347
172
24.1
aNTP (1989).
' Represented as average daily dose (ADD = dose x 5/7 days/week).
TOD (HED) = ADD x DAF. DAF = 0.24 for rats; DAF = 0.14 for mice.
dPODs do not consider UF application.
eBMD modeling was performed with four data points (minus two highest doses).
fChange was >10% compared to control values.
adj = duration adjusted; BMD = benchmark dose; BMDL = benchmark dose lower confidence limit; F = female;
HED = human equivalent dose; LOAEL = lowest-observed-adverse-effect level; M = male; NA = not applicable
(not amenable to BMDS); ND = no data (LOAEL occurs at lowest dose level tested);
NOAEL = no-observed-adverse-effect level; POD = point of departure; UF = uncertainty factor.
Potential points of departure (PODs) from both sub chronic-duration studies were
modeled using the EPA's Benchmark Dose Software (BMDS, Version 2.6) (see Table 7).
Appendix C presents the details of the modeling procedure. Benchmark dose (BMD) modeling
could not be performed for effects in the spleen of rats because the incidence was 100% at the
28
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lowest dose in all cases and the severity data were reported as mean severity score without an
indication of variance (standard deviation [SD] or standard error of the mean).
In EPA's Recommended Use of Body Weight4 as the Default Method in Derivation of
the Oral Reference Dose (U.S. EPA, 201 lb), the Agency endorses a hierarchy of approaches to
derive human equivalent oral exposures from data from laboratory animal species, with the
preferred approach being physiologically based toxicokinetic modeling. Other approaches may
include using some chemical-specific information, without a complete physiologically based
toxicokinetic model. In lieu of chemical-specific models or data to inform the derivation of
human equivalent oral exposures, EPA endorses body-weight scaling to the 3/4 power
(i.e., BW3/4) as a default to extrapolate toxicologically equivalent doses of orally administered
agents from all laboratory animals to humans for the purpose of deriving an RfD under certain
exposure conditions. More specifically, the use of BW3 4 scaling for deriving an RfD is
recommended when the observed effects are associated with the parent compound or a stable
metabolite, but not for portal-of-entry effects.
A validated human physiologically based toxicokinetic model for /V,/V-dimethylaniline is
not available for use in extrapolating doses from animals to humans. Furthermore, spleen lesions
are not a portal-of-entry effect. Therefore, scaling by BW3/4 is relevant for deriving human
equivalent doses (HEDs) for this effect.
Following U.S. EPA (2011b) guidance, the POD for spleen lesions in adult rats is
converted to an HED through application of a dosimetric adjustment factor (DAF)1 derived as
follows:
DAF = (BWa1/4 - BWh1/4)
where:
DAF = dosimetric adjustment factor
BWa = animal body weight
BWh = human body weight
Using a BWa of 0.25 kg for rats and 0.025 kg for mice, and a BWh of 70 kg for humans
(U.S. EPA, 1988), the resulting DAFs are 0.24 and 0.14 for rats and mice, respectively. Each
POD candidate is multiplied by the appropriate species-specific DAF to obtain the POD (HED)
(see Table 7).2
The lowest point of departure human equivalent dose (POD [HED]) following
subchronic-duration treatment of N, A-dimethylani 1 ine appears to be increased kidney
hemosiderosis in female rats with a POD (HED) of 0.75 mg/kg-day (10% benchmark dose lower
confidence limit [BMDLio] = 3.1 mg/kg-day). However, because no NOAEL or BMDL was
identified for effects in the spleen of rats, there is uncertainty if other nonsplenic PODs (in rats
and mice) would be protective for splenic effects. In addition, there is more support for
:As described in detail in Recommended Use of Body Weight4 as the Default Method in Derivation of the Oral
Reference Dose (U.S. EPA. 201 lb), rate-related processes scale across species in a manner related to both the direct
(BW11) and allometric scaling (BW3/4) aspects such that BW3/4 ^ BW1'1 = BW converted to a
DAF = BWa"4 - BWi,1'4.
2For example, LOAEL (HED) = 22.32 mg/kg-day x DAF = 22.32 mg/kg-day x 0.24 = 5.357 mg/kg-day.
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increased toxicity of the spleen being selected as the critical effect, including greater severity of
observed lesions, consistency in lesion development across sexes and species, and coherence
with other adverse N,iV-dimethylaniline-induced events (i.e., methemoglobinemia,
splenomegaly). The severity of the histopathological responses reported in the spleen (i.e., mild)
were greater than that reported for the kidney (i.e., minimal) and an increase in splenic lesions
was observed in both male and female rats and mice. Based on the available data, the LOAEL
(HED) for spleen lesions in male and female rats (5.357 mg/kg-day) is selected as the POD
for derivation of the subchronic p-RfD.
The subchronic p-RfD for A', A'-di methyl aniline, based on a LOAEL (HED) of
5.357 mg/kg-day for spleen lesions, is derived as follows:
Subchronic p-RfD = LOAEL (HED) - UFC
= 5.357 mg/kg-day ^ 3,000
= 2 x 10"3 mg/kg-day
The composite uncertainty factor (UFc) for the subchronic p-RfD for
TV,TV-dimethyl aniline is 3,000, as summarized in Table 8.
Table 8. Uncertainty Factors for the Subchronic p-RfD for
AyV-Dimethylaniline (CASRN 121-69-7)
UF
Value
Justification
UFa
3
A UFa of 3 (10°5) is applied to account for uncertainty in characterizing the toxicokinetic or
toxicodynamic differences between rats and humans following oral \ , \ -dimcthvlanilinc treatment.
The toxicokinetic uncertainty has been accounted for by calculating a HED through application of a
DAF as outlined in the EPA's Recommended Use of Body Weight3/4 as the Default Method in
Derivation of the Oral Reference Dose ('U.S. EPA. 2011b).
UFd
10
A UFd of 10 is applied to account for deficiencies and uncertainties in the database. The available
subchronic- and chronic-duration oral toxicity studies and the developmental toxicity screening
study lbr A , . Y-d i me t hy 1 a n i 1 i ne are not comprehensive. No oral reproductive studies are available
for TV, TV-dime thy laniline.
UFh
10
A UFh of 10 is applied for intraspecies variability to account for human-to-human variability in
susceptibility in the absence of quantitative information to assess toxicokinetic and toxicodynamic
variability of \ , \ -diincthvlaniline in humans.
UFl
10
A UFl of 10 is applied for LOAEL-to-NOAEL extrapolation because the POD is a LOAEL.
UFS
1
A UFs of 1 is applied because the principal studv is a subchronic-duration studv (13 wk) CAbdo et
al.. 1990: NTP. 19891
UFC
3,000
Composite UF = UFA x UFD x UFH x UFL x UFS.
DAF = dosimetric adjustment factor; HED = human equivalent dose; LOAEL = lowest-observed-adverse-effect
level; NOAEL = no-observed-adverse-effect level; POD = point of departure.
The confidence in the subchronic p-RfD for A'A-dimethylaniline is low as described in
Table 9.
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Table 9. Confidence Descriptors for the Subchronic p-RfD for
TV,TV-Dimethylaniline (CASRN 121-69-7)
Confidence Categories
Designation
Discussion
Confidence in study
L
Confidence in the principal study is low. Despite being a peer-reviewed
study that used five dose groups in both sexes of two species, a
comprehensive evaluation of potential effects was not conducted
(hematology, clinical chemistry, and organ-weight measurements were
not performed). In addition, a NOAEL dose was not identified because
spleen lesions occurred in every animal at all dose levels.
Confidence in database
L
There is low confidence in the database. The available subchronic- and
chronic-duration oral toxicity studies for TV.iV-dimethylaniline are not
comprehensive. The single developmental toxicity screening study
available is not comprehensive (no internal examination of fetal
development). No oral reproductive studies are available for
.Y, Y-dimcthvlanilinc.
Confidence in subchronic
p-RfDa
L
The overall confidence in the subchronic p-RfD is low.
"The overall confidence cannot be greater than the lowest entry in the table.
L = low; NOAEL = no-observed-adverse-effect level; p-RfD = provisional oral reference dose.
Derivation of Chronic Provisional Oral Reference Dose
A chronic p-RfD is not derived because an oral RfD is available on EPA's IRIS database
(U.S. EPA. 19871
DERIVATION OF INHALATION REFERENCE CONCENTRATIONS
Human and animal data are inadequate to derive subchronic or chronic provisional
reference concentrations (p-RfCs). A subchronic-duration inhalation study is available for
TV, A;-di methyl aniline (Markosyan. 1969). This study exposed male albino rats (number not
specified) to nominal concentrations of 0, 0.0055, or 0.3 mg/m3 TV, TV-dim ethyl aniline in air
continuously for 100 days. Effects were reported in the blood, spleen, liver, brain, and lung at
the high-exposure concentration; however, the study report does not provide adequate details to
allow for a thorough review of the methods and results. No details were provided regarding the
method used to generate the chamber air concentrations, and measured concentrations were not
reported for this study. The study results are presented primarily in a qualitative statement, with
no indication of the incidence of occurrence or the magnitude of any effect. As a result of the
uncertainties in the available inhalation data for TV,TV-dimethylaniline, subchronic and chronic
p-RfCs are not derived.
CANCER WEIGHT-OF-EVIDENCE DESCRIPTORS
The cancer weight-of-evidence (WOE) descriptors for TV,TV-dimethylaniline are presented
in Table 10.
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Table 10. Cancer Weight-of-Evidence Descriptors for
AyV-Dimethylaniline (CASRN 121-69-7)
Possible WOE Descriptor
Designation
Route of Entry (oral,
inhalation, or both)
Comments
"Carcinogenic to Humans "
NS
NA
There are no human data to support
this.
"Likely to Be Carcinogenic to
Humans "
NS
NA
There are no sufficient animal studies
to support this.
"Suggestive Evidence of
Carcinogenic Potential"
Selected
Oral
There are sufficient animal studies
to support this selection.
"Inadequate Information to Assess
Carcinogenic Potential"
Selected
Inhalation
No carcinogenicity studies are
available that evaluated inhalation
exposure.
"Not Likely to Be Carcinogenic to
Humans "
NS
NA
No evidence of noncarcinogenicity is
available.
NA = not applicable; NS = not selected.
Under the 2005 Guidelines for Carcinogen Risk Assessment (U.S. EPA. 2005). there is
"Suggestive Evidence of Carcinogenic Potential" for A'A-di methyl aniline by an oral route of
exposure and "Inadequate Information to Assess Carcinogenic Potential" by inhalation
(see Table 10). These descriptors are based on (1) suggestive evidence of carcinogenicity in
orally treated male rats and (2) a lack of carcinogenicity studies in animals exposed by
inhalation.
No human studies are available to assess the potential for carcinogenesis following
exposure to A'A-di methyl aniline. Carcinogenesis studies of N, TV-dimethyl aniline were
conducted in F344/N rats and B6C3Fi mice treated via gavage for 103 weeks (NTP. 1989). A
review of the study findings indicated that both rats and mice could have tolerated a higher dose
of A', A'-di methyl aniline, suggesting that the carcinogenic responses may have been greater had
larger doses been administered in these studies. Nevertheless, the NTP concluded that there was
"Some Evidence of Carcinogenic Activity" in male rats based on the increased incidence of
sarcomas or osteosarcomas (combined) in the spleen (no evidence of carcinogenicity in female
rats). The splenic sarcomas were described as anaplastic neoplasms with histologic
characteristics of fibrosarcomas, osteosarcomas, or hemangiosarcomas. The sarcomas observed
in the spleen were varied in morphology, but there was no evidence to suggest they were derived
from other tissues (e.g., bone). The osteosarcoma observed in the spleen may have differentiated
from a splenic sarcoma because sarcomas, which are mesenchymal origin, can undergo
osteoblastic differentiation toward osteosarcomas (Nlutsaers and Walk lev. 2014). In fact, one
splenic sarcoma observed following N,iV-dimethylaniline treatment had a focus of minimal
osteoid production that the NTP proposed as evidence of early differentiation toward
osteosarcoma. Because there is no evidence to suggest the A'A-di methyl aniline-induced
sarcomas or osteosarcomas are derived from different tissues, it is appropriate to combine the
incidence of these neoplasms. The combined incidence of tumors in the high-dose group
(21 mg/kg-day) increased compared to the concurrent control group (p = 0.06 by incidental
tumor test and Fisher's exact test), and a statistically significant dose-response trend was
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observed (p = 0.01 by Cochran-Armitage trend test) (see Tables 11 and B-8). The site and sex
differences associated with these neoplasms are consistent with those induced by aniline and
other structurally analogous chemicals (N I P. 1989). In addition, the incidence of splenic
sarcoma in high-dose males (3/50) exceeded the greatest historical incidence of splenic sarcoma
in control male rats given corn oil gavage (1/45), as well as equaled the overall historical
incidence for males in NTP corn oil gavage studies (3/2,081) (N I P. 1989).
Table 11. Incidence of Splenic Sarcoma or Osteosarcoma in Male F344/N Rats Exposed to
]V,]V-Dimethylaniline (CASRN 121-69-7) by Gavage 5 Days/Week for 2 Years"
Adjusted Daily Dose (HED) (mg/kg-d)
Endpoint
0 (Control)
2 (0.5)
21 (5.0)
Splenic sarcoma or osteosarcoma
0/49* (0%)
0/49 (0%)
4/50 (8%)
•'N I P ( 1989).
*Trend test p < 0.05 (life table test, incidental tumor test, and Cochran-Armitage trend test performed by study
authors).
The NTP concluded that there was "equivocal evidence of carcinogenic activity " in
female mice based on increased incidence of squamous cell papillomas of the forestomach (no
evidence of carcinogenicity in male mice). Female mice showed a statistically significant
increase in the incidence of this tumor in the high-dose group compared to concurrent controls
(p = 0.04), and a statistically significant dose-response trend was observed (p = 0.02)
(see Table B-9). However, these tumors were not considered for deriving a provisional oral
slope factor (p-OSF) for several reasons. Forestomach papillomas are considered a
portal-of-entry effect in gavage treated animals. Portal-of-entry effects would be expected to
occur in both sexes because direct toxicity would not be impacted by sex-related differences in
toxicokinetics. No increase in forestomach tumors was observed in male mice. Additionally, the
tumor incidence in high-dose female mice did not differ markedly from the greatest historical
control incidence in female mice given corn oil gavage (8/50 vs. 5/44). The historical incidence
for this tumor type in female mice given corn oil gavage in NTP studies varied from 0/50 to 5/44
with an overall incidence of 32/2,047. Finally, no squamous cell carcinomas were identified in
high-dose female mice, suggesting that the observed forestomach papillomas might not be
progressive. In the diagnosis of papillomas, the NTP noted uncertainty whether "these
proliferative lesions are true neoplasms or merely an advanced stage of hyperplasia" (NTP.
1989).
As stated in the Guidelines for Carcinogen Risk Assessment (U.S. EPA. 2005), an
example of supporting data to conclude that there is "Suggestive Evidence of Carcinogenic
Potential" includes "a small, and possibly not statistically significant, increase in tumor
incidence observed in a single animal or human study that does not reach the weight of evidence
for the descriptor 'Likely to Be Carcinogenic to Humans. Based on this example from the
U.S. EPA's Guidelines for Carcinogen Risk Assessment (U.S. EPA. 2005) and the data available
from the study in male rats, there is "Suggestive Evidence of Carcinogenic Potential" for
A', A'-di methyl aniline.
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MODE OF ACTION
The Guidelines for Carcinogen Risk Assessment (U.S. EPA. 2005) define MO A for
carcinogenicity "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 some of the possible modes of carcinogenic action for any
given chemical include "mutagenicity, mitogenesis, inhibition of cell death, cytotoxicity with
reparative cell proliferation, and immune suppression." The available studies of
TV,TV-dimethyl aniline provide evidence for some key events leading to tumor formation in the
spleen, with both genotoxic and nongenotoxic events being plausible.
Although not mutagenic in bacteria (Taningfaer et ai. 1993; N I P. 1989; Model mans et
al.. 1986; Mori et aL 19801 TV, A;-di methyl aniline is both mutagenic and clastogenic in
mammalian cells (Taningfaer et al. 1993; Lovedav et al. 1989; N I P. 1989) (see Table 4).
Genotoxicity appears to be primarily due to one or more of the compound's metabolites
(Taningfaer et al, 1993; Lovedav et al, 1989; N I P. 1989), although likely not by direct damage
to DNA (Taningfaer et al. 1993; Yosfaimi et al.. 1988). These results suggest that a genotoxic
MOA is plausible for TV,TV-dimethylaniline-induced tumors.
As described above, toxicokinetic and mechanistic evidence suggests that
TV,TV-dimethyl aniline may act through a similar hematological mechanism as aniline, a major
metabolite of TV, TV-dim ethyl aniline. Genotoxicity studies of aniline and aniline metabolites
reviewed by Bombard and Herbold (2005) suggest that the carcinogenic activity of aniline may
not be due to genotoxicity; however, the evidence is not consistent for all endpoints. MOA
information reviewed by Bus and Popp (1987) suggest the following possible key events for
aniline carcinogenicity: (1) accumulation of the parent compound or metabolites carried to the
spleen by RBCs; (2) covalent binding to erythrocyte and splenic macromolecules; (3) deposition
of erythrocyte debris (e.g., iron) resulting in hemosiderin accumulation, vascular congestion, and
hemorrhage; and (4) hyperplasia and fibrosis leading to formation of splenic tumors
(i.e., fibrosarcomas). Some of these key events may also apply to the splenic toxicity of
TV,TV-dimethyl aniline; however, evidence to support these key events following exposure to
TV,TV-dimethyl aniline is limited. Hemosiderin accumulation, fibrosis, sarcoma, and osteosarcoma
were observed in the spleens of male rats given TV, A;-di methyl aniline orally for 2 years (NIP.
1989). Still, mechanistic studies that evaluate these possible key events following exposure to
TV,TV-dimethyl aniline are limited; thus, uncertainty remains on the principal MOA leading to
splenic tumors following TV,TV-dimethylaniline exposure.
DERIVATION OF PROVISIONAL CANCER POTENCY VALUES
Derivation of Provisional Oral Slope Factor
A p-OSF for TV,TV-dimethyl aniline is derived from the combined incidence of splenic
sarcoma or osteosarcoma in male rats from the NTP (1989) study (see Table 1 1 for incidence
data).
As noted in Table 10, the EPA concluded that there is "Suggestive Evidence of
Carcinogenic Potential" for TV,TV-dimethylaniline by an oral route of exposure. The Guidelines
for Carcinogen Risk Assessment (U.S. EPA. 2005) state: "When there is suggestive evidence, the
Agency generally would not attempt a dose-response assessment, as the nature of the data
generally would not support one; however, when the evidence includes a well-conducted study,
quantitative analyses may be useful for some purposes, for example, providing a sense of the
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magnitude and uncertainty of potential risks, ranking potential hazards, or setting research
priorities. In each case, the rationale for the quantitative analysis is explained, considering the
uncertainty in the data and the suggestive nature of the weight of evidence. These analyses
generally would not be considered Agency consensus estimates."
Prior to dose-response modeling, doses administered to the animals in the studies by NTP
(1989) were converted to HEDs according to the equation below:
Dose (HED) = Dose x (BWa - BWh)14
where:
Dose = average daily animal dose of A'A'-di methyl aniline
BWa = reference animal body weight3
BWh = 70 kg, reference human body weight (U.S. EPA. 1988)
Using a BWa of 0.25 kg for rats and a BWh of 70 kg for humans, the resulting default
DAF is 0.24 (U.S. EPA. 2011b. 2005).4
Multistage-cancer models in the EPA BMDS (Version 2.6) were fit to the tumor
incidence data shown in Table 11, and modeling results are summarized in Appendix C. The
benchmark response (BMR) used was 10% extra risk. Calculated POD (HED) doses were used
for modeling. The 1- and 2-degree multistage-cancer models provided adequate fit to this data
set. The 2-degree model had the lower Akaike's information criterion (AIC) and was selected.
The dose associated with 10% extra risk (BMDio) and its 95% lower confidence limit (BMDLio)
are 5.6 and 3.7 mg/kg-day, respectively (see Table C-l in Appendix C).
The MOA by which A', A'-di methyl aniline induces splenic tumors is not known; both
genotoxic and nongenotoxic contributions are plausible. In the absence of definitive
information, a linear approach is used to obtain the slope from the POD.
Using the linear approach, a p-OSF of 2.7 x 10"2 (mg/kg-day)"1 is derived for
TV,TV-dimethyl aniline from the BMDLio (HED) of 3.7 mg/kg-day for splenic tumors in male rats
treated by gavage for 2 years, as follows:
p-OSF = BMR -h BMDLio (HED)
= 0.1 -^3.7 mg/kg-day
= 2.7 x 10"2 (mg/kg-day)"1
Derivation of Provisional Inhalation Unit Risk
The absence of data identified on the carcinogenicity of A' A'-di m eth yl an i 1 i n e following
inhalation exposure precludes the derivation of a quantitative estimate (i.e., p-IUR) for inhalation
exposure.
3Time-weighted body weight was not reported by the study authors or calculable from reported study data. Default
animal body weights (0.25 kg for rats and 0.025 kg for mice) were used in calculating HED values.
4For example, POD (HED) = 21 mg/kg-day x 0.24 = 5.2 mg/kg-day.
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APPENDIX A. SCREENING PROVISIONAL VALUES
No provisional screening values are identified for iV,iV-dimethylaniline.
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APPENDIX B. DATA TABLES
Table B-l. Survival and Body Weights in Male and Female F344/N Rats Exposed to
jV,jV-Dimethylaniline (CASRN 121-69-7) by Gavage for 14 Days"
Exposure Group (mg/kg-d)
Endpoint
0 (control)
94
188
375
750
1,500
Survivalb
Males
5/5
5/5
5/5
5/5
1/5
0/5
Females
5/5
5/5
5/5
5/5
0/5
0/5
Mean Body Weight (g)c
Males
Terminal body weight
199 ±6
194 ± 7 (-3%)
187 ± 4 (-6%)
169 ± 6* (-15%)
105 (-47%)
ND
Body-weight gain
73 ±5
64 ± 2 (-12%)
61 ± 3 (-16%)
47 ± 2* (-36%)
-16
ND
(-122%)
Females
Terminal body weight
135 ±2
129 ± 3 (-4%)
127 ±2*
131 ±5 (-3%)
ND
ND
(-6%)
Body-weight gain
32 ±2
32 ± 2 (0%)
30 ± 2 (-6%)
26 ± 3 (-19%)
ND
ND
Splenomegalyd
Males and females
0/10
3/10
9/10*
10/10*
1/1
ND
combined
aNTP (1989).
bNumber surviving/number initially in group (deaths occurred on Days 3, 4, and 6).
°Values expressed as group mean body weight ± standard error of the mean (% change compared with control);
% change control = [(treatment mean - control mean) control mean] x 100.
dNumber with splenomegaly/number examined.
* Statistically significantly different from controls at p< 0.05, as calculated for this review (unpaired /-test for body
weight; Fisher's exact test for splenomegaly).
ND = no data reported due to 100% mortality.
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Table B-2. Survival and Body Weights in Male and Female B6C3Fi Mice Exposed to
jV,jV-Dimethylaniline (CASRN 121-69-7) by Gavage for 15 Days"
Exposure Group (mg/kg-d)
Endpoint
0 (control)
94
188
375
750
1,500
Survivalb
Males
5/5
5/5
4/5
5/5
0/5
0/5
Females
5/5
5/5
5/5
5/5
0/5
0/5
Mean Body Weight (g)c
Males
Terminal body weight
26.0 ±0.6
28.1 ± 1.3 (+8%)
26.6 ± 0.5 (+2%)
28.6 + 0.7 (+10%)
ND
ND
Body-weight gain
0.8 ±0.2
2.1 ±0.4*
2.1±0.7
2.1+0.4* (+162%)
ND
ND
(+162%)
(+162%)
Females
Terminal body weight
21.1 ± 0.3
21.3 ±0.6 (+1%)
21.3 + 0.7 (+1%)
22.8 + 0.6* (+8%)
ND
ND
Body-weight gain
1.3 ±0.4
1.5 ±0.3 (+15%)
1.6 + 0.3 (+23%)
2.4 + 0.6 (+85%)
ND
ND
Splenomegalyd
Males
0/5
0/5
1/5
2/5
ND
ND
Females
0/5
0/5
0/5
3/5
ND
ND
•'N' T'P ( 1989).
bNumber surviving/number initially in group (deaths occurred on Days 3, 4, 6, 9, and 12).
°Values expressed as group mean body weight ± standard error of the mean (% change compared with control); %
change control = [(treatment mean - control mean) + control mean] x 100.
dNumber with splenomegaly/number examined.
* Statistically significantly different from controls at p< 0.05, as calculated for this review (unpaired /-test).
ND = no data reported due to 100% mortality.
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Table B-3. Survival and Body Weight of Male and Female F344/N Rats Exposed to
jV,jV-Dimethylaniline (CASRN 121-69-7) by Gavage 5 Days/Week for 13 Weeks3
Endpoint
Average Daily Dose (mg/kg-d)
0 (control)
22.32
44.6
89.3
179
357
Survivalb
Males
10/10
10/10
10/10
10/10
10/10
9/10
Females
10/10
10/10
9/10
9/10
9/10
10/10
Mean Body Weights (g)c
Males
Terminal body
weight
345 ±5
331 ±8
(-4%)
332 ±5
(-4%)
321 ±5*
(-7%)
292 ± 5*
(-15%)
251 ±9*
(-27%)
Body-weight gain
223 ±6
208 ±7
(-7%)
204 ±3*
(-9%)
194 ±4*
(-13%)
168 ±3*
(-25%)
130 ±8*
(-42%)
Females
Terminal body
weight
193 ±2
190 ±2
(-2%)
188 ±2
(-3%)
187 ±2*
(-3%)
185 ±2*
(-4%)
183 ±4*
(-5%)
Body-weight gain
90 ±3
92 ±2
(+2%)
91 ± 2
(+1%)
88 ±2
(-2%)
86 ±2
(-4%)
84 ±4
(-7%)
aAbdo et al. (1990): NTP (1989).
bNumber surviving/number initially in group (deaths occurred during Weeks 2, 3, and 7).
0Values expressed as group mean body weight ± standard error of the mean (% change compared with control);
% change control = [(treatment mean - control mean) control mean] x 100.
* Statistically significantly different from controls at p< 0.05, as calculated for this review (unpaired /-test).
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Table B-4. Selected Histopathologic Findings in Male and Female F344/N Rats Exposed to
jV,jV-Dimethylaniline (CASRN 121-69-7) by Gavage 5 Days/Week for 13 Weeks3
Endpoint
Average Daily Dose (mg/kg-d)
0 (control)
22.32
44.6
89.3
179
357
Males
Spleen
Hematopoiesis
0/10
10/10* (2.3)b
10/10* (2.0)
10/10* (2.8)
10/10* (3.5)
9/9* (4.0)
Hemosiderosis
0/10
10/10* (2.3)
10/10* (2.7)
10/10* (2.9)
10/10* (3.8)
9/9* (4.8)
Liver
Hemosiderosis
0/10
0/10
2/10(1.5)
9/10* (1.3)
10/10* (2.5)
9/9* (3.2)
Kidney
Hemosiderosis
0/10
0/10
7/10* (1.1)
10/10* (2.0)
10/10* (3.7)
9/9* (4.2)
Testis
Hemosiderosis
0/10
Not examined
Not examined
0/10
10/10* (1.0)
9/9* (1.0)
Bone marrow
Hyperplasia
0/10
0/10
2/10 (1.0)
9/10* (1.3)
10/10* (2.1)
8/8* (3.0)
Females
Spleen
Hematopoiesis
2/10 (2.0)
10/10* (2.1)
10/10* (2.4)
10/10* (2.9)
10/10* (2.9)
10/10* (3.9)
Hemosiderosis
0/10
10/10* (2.0)
9/10* (3.0)
9/10* (3.2)
9/10* (3.1)
10/10* (4.0)
Liver
Hemosiderosis
0/10
0/10
6/10* (1.0)
9/10* (1.6)
9/10* (2.1)
10/10* (3.5)
Kidney
Hemosiderosis
1/10 (1.0)
6/10* (1.0)
9/10* (1.3)
9/10* (2.1)
9/10* (3.6)
9/10* (3.6)
Bone marrow
Hyperplasia
0/10
0/10
1/10(1.0)
9/10* (1.4)
8/10* (2.1)
9/10* (1.9)
aAbdo et al. (1990): NTP (1989).
bNumber with histopathological lesion/number examined; mean severity score in parentheses: Grade 1 = minimal;
2 = mild; 3 = moderate; 4 = marked; 5 = severe.
* Statistically significantly different from controls at p< 0.05, as calculated for this review (Fisher's exact test).
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Table B-5. Survival and Mean Body Weights of Male and Female B6C3Fi Mice Exposed
to AyV-Dimethylaniline (CASRN 121-69-7) by Gavage 5 Days/Week for 13 Weeks"
Endpoint
Average Daily Dose (mg/kg-d)
0 (control)
22.32
44.6
89.3
179
357
Survivalb
Males
9/10
8/10
7/10
10/10
9/10
10/10
Females
10/10
10/10
9/10
10/10
10/10
10/10
Mean Body Weights (g)c
Males
Terminal
body weight
38.6 ± 1.0
34.8 ±0.5*
(-10%)
35.1 ±0.9*
(-9%)
33.9 ± 1.0*
(-12%)
34.9 ± 1.5
(-10%)
35.3 ±0.7*
(-9%)
Body-weight
gain
8.3 ±0.8
5.5 ± 1.0*
(-34%)
5.4 ±0.4*
(-35%)
5.1 ±0.9*
(-39%)
7.6 ± 1.0
(-8%)
4.9 ±0.8*
(-41%)
Females
Terminal
body weight
28.4 ± 1.2
26.4 ±0.5
("7%)
26.7 ±0.9
(-6%)
25.9 ±0.7
(-9%)
28.0 ±0.6
(-1%)
27.8 ±0.7
(-2%)
Body-weight
gain
5.0 ±0.7
1.7 ±0.3*
(-66%)
3.5 ±0.8
(-30%)
2.7 ±0.4*
(-46%)
3.9 ±0.5
(-22%)
4.5 ±0.5
(-10%)
aAbdo et al. (1990): NTP (1989).
bNumber surviving/number initially in group (deaths occurred during Weeks 1, 2, 3, 8, 10, and 12).
°Values expressed as group mean body weight ± standard error of the mean (% change compared with control);
% change control = [(treatment mean - control mean) control mean] x 100.
* Statistically significantly different from controls at p < 0.05, as calculated for this review (unpaired /-test).
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Table B-6. Selected Histopathologic Findings in Male and Female B6C3Fi Mice Exposed
to ]V,]V-Dimethylaniline (CASRN 121-69-7) by Gavage 5 Days/Week for 13 Weeks"
Endpointb
Average Daily Dose (mg/kg-d)
0 (control)
22.32
44.6
89.3
179
357
Males
Spleen
Hematopoiesis
1/10 (1.0)b
1/10 (2.0)
6/9* (1.4)
9/10* (1.9)
10/10* (2.2)
10/10* (3.9)
Hemosiderosis
1/10 (3.0)
0/10
5/9 (2.0)
9/10* (2.0)
9/10* (2.9)
10/10* (4.6)
Liver
Hematopoiesis
1/10(1.0)
0/10
0/10
0/9
0/10
6/10* (2.3)
Hemosiderosis
1/10(1.0)
1/10(1.0)
0/10
9/9* (1.1)
9/10* (3.1)
9/10* (3.7)
Kidney
Hemosiderosis
0/10
0/10
0/3
Not examined
0/10
8/10* (2.6)
Females
Spleen
Hematopoiesis
0/10
0/10
8/10* (1.9)
10/10* (1.8)
10/10* (2.4)
10/10* (3.9)
Hemosiderosis
0/10
0/10
8/10* (2.1)
10/10* (2.0)
10/10* (2.9)
10/10* (5.0)
Liver
Hematopoiesis
0/10
Not examined
0/10
0/10
0/10
8/10* (2.1)
Hemosiderosis
1/10(1.0)
Not examined
0/10
10/10* (1.0)
10/10* (3.2)
10/10* (3.3)
Kidney
Hemosiderosis
0/10
Not examined
Not examined
0/10
10/10* (1.2)
10/10* (2.8)
aAbdo et al. (1990): NTP (1989).
bNumber of animals with histopathological lesion/number of animals examined; mean severity in parenthesis:
Grade 1 = minimal; 2 = mild; 3 = moderate; 4 = marked; 5 = severe.
* Statistically significantly different from controls at p< 0.05, as calculated for this review (Fisher's exact test).
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Table B-7. Selected Nonneoplastic Lesions in Male and Female F344/N Rats Exposed to
]V,]V-Dimethylaniline (CASRN 121-69-7) by Gavage 5 Days/Week for 2 Years"
Endpoint
Average Daily Dose (mg/kg-d)
0 (control)
2
21
Males
Spleen
Hematopoiesis
44/49b
48/49
50/50
Normal
5/49
1/49
0/50
Minimal
41/49
38/49
29/50
Mild
2/49
7/49
19/50*
Moderate
0/49
3/49
2/50
Marked
1/49
0/49
0/50
Mean severity score0
1.00 ±0.09
1.24 ±0.09
1.46 ±0.08**
Hemosiderosis
43/49
47/49
49/50
Normal
6/49
2/49
1/50
Minimal
39/49
17/49*
13/50*
Mild
4/49
29/49*
25/50*
Moderate
0/49
1/49
11/50*
Marked
0/49
0/49
0/50
Mean severity score
0.96 ±0.06
1.59 ±0.09**
1.92 ± 0.11**
Fibrosis
5/49
2/49
22/50**
Fatty metamorphosis
0/49
1/49
10/50**
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Table B-7. Selected Nonneoplastic Lesions in Male and Female F344/N Rats Exposed to
]V,]V-Dimethylaniline (CASRN 121-69-7) by Gavage 5 Days/Week for 2 Years"
Endpoint
Average Daily Dose (mg/kg-d)
0 (control)
2
21
Females
Liver
Chronic focal inflammation
17/50
20/50
30/50*
Spleen
Hematopoiesis
47/50
48/49
49/49
Normal
3/50
1/49
0/49
Minimal
25/50
16/49
9/49*
Mild
22/50
30/49
38/49*
Moderate
0/50
1/49
1/49
Marked
0/50
1/49
1/49
Mean severity score
1.38 ±0.09
1.69 ±0.09
1.88 ±0.08**
Hemosiderosis
47/50
48/49
49/49
Normal
3/50
1/49
0/49
Minimal
10/50
5/49
1/49*
Mild
37/50
29/49
20/49*
Moderate
0/50
14/49*
28/49*
Marked
0/50
0/49
0/49
Mean severity score
1.68 ±0.08
2.14 ±0.10**
2.55 ±0.08**
Fibrosis
2/50
0/49
2/49
Fatty metamorphosis
0/50
1/49
0/49
aNTP (1989).
bNumber with histological lesion/number examined.
°Mean ± standard error of the mean; 0 = normal; 1 = minimal; 2 = mild; 3 = moderate; 4 = marked.
* Statistically significantly different from controls at p< 0.05, as calculated for this review (Fisher's exact test).
**p < 0.01 (statistics reported by study authors; Mann-Whitney U test for severity data; incidental tumor test for
incidence data).
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Table B-8. Selected Neoplastic Lesions in Male and Female F344/N Rats Exposed to
]V,]V-Dimethylaniline (CASRN 121-69-7) by Gavage 5 Days/Week for 2 Years"
Endpoint
Average Daily Dose (mg/kg-d)
0 (control)
2
21
Males
Splenic sarcoma
0/49* (0%)
0/49 (0%)
3/50 (6%)
Splenic osteosarcoma
0/49 (0%)
0/49 (0%)
1/50 (2%)
Splenic sarcoma or osteosarcoma
0/49* (0%)
0/49 (0%)
4/50 (8%)
Females
Splenic sarcoma
1/50 (2%)
0/49 (0%)
0/49 (0%)
aNTP (1989).
*Trend test p < 0.05 (life table test, incidental tumor test, and Cochran-Armitage trend test performed by study
authors).
Table B-9. Selected Histopathological Lesions in Female B6C3Fi Mice Exposed to
]V,]V-Dimethylaniline (CASRN 121-69-7) by Gavage 5 Days/Week for 2 Years3
Endpoint
Average Daily Dose (mg/kg-d)
0 (control)
11
21
Nonneoplastic effects
Forestomach epithelial hyperplasia
8/50 (16%)
11/19 (58%)b
13/50 (26%)
Pituitary gland; chromophobe cell hyperplasia
10/45 (22%)
2/14 (14%)°
16/44 (36%)
Neoplastic effects
Forestomach squamous cell papillomad
2/50* (4%)
2/19 (4%)b
8/50* (16%)
"NTP (1989).
bNineteen forestomachs were examined microscopically at the low dose for this endpoint.
Incomplete sampling of tissues.
historical incidence of squamous cell papillomas or carcinomas (combined) at study laboratory
(mean ± SD): 7/141 (5%± 6%); historical incidence in NTP studies: 32/2,047 (2%± 3%).
*p < 0.05; indicated next to control incidence for dose-response trend (incidental tumor test and Cochran-Armitage
trend test) and treatment group incidence for pair wise comparison to control (incidental tumor test) (statistics
reported by study authors).
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APPENDIX C. BENCHMARK DOSE MODELING RESULTS
MODELING OF NONCANCER ENDPOINTS
As discussed in the body of the report in the "Derivation of Subchronic Provisional Oral
Reference Dose" section, the endpoints selected for benchmark dose (BMD) modeling were:
(1) incidence of kidney, liver, and spleen hemosiderosis in male and female rats; (2) incidence of
spleen hematopoiesis in male and female rats; (3) incidence of bone marrow hyperplasia in male
and female rats; (4) incidence of spleen hemosiderosis and hematopoiesis in male and female
mice; (5) terminal body weight in male mice; (6) incidence of liver hemosiderosis in male and
female mice; and (7) splenomegaly in male and female mice (Abdo et aL 1990; N I P. 1989).
The animal doses in the study, converted to adjusted daily doses (ADDs) of N, TV-dimethyl aniline,
were used in the BMD modeling; the data are shown in Tables B-4, B-5, and B-6.
Modeling Procedure for Dichotomous Noncancer Data
BMD modeling of dichotomous noncancer data was conducted with the EPA's
Benchmark Dose Software (BMDS, Version 2.5). For these data, the Gamma, Logistic,
Log-Logistic, Log-Probit, Multistage, Probit, and Weibull dichotomous models available within
the software were fit using a benchmark response (BMR) of 10% extra risk. The multistage
model is run for all polynomial degrees up to n - 1, where n is the number of dose groups
including control. Adequacy of model fit was judged based on the x2 goodness-of-fit p-value
(p > 0.1), scaled residuals at the data point (except the control) closest to the predefined
benchmark response (absolute value <2.0), and visual inspection of the model fit. In the cases
where no best model was found to fit to the data, a reduced data set without the high-dose group
was further attempted for modeling and the result was present along with that of the full data set.
Among all of the models providing adequate fit, the benchmark dose lower confidence limit
(BMDL) from the model with the lowest Akaike's information criterion (AIC) was selected as a
potential point of departure (POD) when BMDL values were sufficiently close. Otherwise, the
lowest BMDL was selected as a potential POD.
Modeling Procedure for Continuous Noncancer Data
BMD modeling of continuous noncancer data was conducted with the EPA's BMDS
(Version 2.5). For these data, all continuous models available within the software were fit using
a BMR of 10% extra risk or 1 standard deviation (SD). Adequacy of model fit was judged based
on the x2 goodness-of-fit />value (p > 0.1), magnitude of the scaled residuals at the data point
(except the control) closest to the predefined benchmark response (absolute value <2.0), and
visual inspection of the model fit. In addition to these three criteria forjudging the adequacy of
model fit, a determination was made as to whether the variance across dose groups was
homogeneous. If a homogeneous variance model was deemed appropriate based on the
statistical test provided in BMDS (i.e., Test 2), the final BMD results were estimated from the
homogeneous variance model. If the test for homogeneity of variance was rejected (p < 0.1), the
model was run again while modeling the variance as a power function of the mean to account for
this nonhomogeneous variance. If this nonhomogeneous variance model did not adequately fit
the data (i.e., Test 3;p<0. 1), the data set was considered unsuitable for BMD modeling. In the
cases where no best model was found to fit to the data, a reduced data set without the high-dose
group was further attempted for modeling and the result was present along with that of the full
data set. Among all of the models providing adequate fit, the BMDL from the model with the
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lowest AIC was selected as a POD when BMDL values were sufficiently close. Otherwise, the
lowest BMDL was selected as a potential POD.
MODELING OF CANCER ENDPOINTS
As discussed in the body of the report in the "Derivation of Provisional Oral Slope
Factor" section, the tumor type selected for BMD modeling was splenic sarcomas or
osteosarcomas in male rats administered N, A-dimethylani 1 ine via gavage 5 days/week for
103 weeks (N I P. 1989). The tumor incidences and associated human equivalent doses (HEDs)
used in the modeling are shown in Tables 11 and B-8.
Modeling Procedure for Cancer Incidence Data
The model-fitting procedure for dichotomous cancer incidence data is as follows. The
multistage-cancer model in the EPA's BMDS (Version 2.6) is fit to the incidence data using the
extra risk option. The multistage-cancer model is run for all polynomial degrees up to n - 1
(where n is the number of dose groups including control). An adequate model fit is judged by
three criteria: (1) goodness-of-fit/?-value (p > 0.1), (2) visual inspection of the dose-response
curve, and (3) scaled residual at the data point (except the control) closest to the predefined
BMR. Among all the models providing adequate fit to the data, the BMDL from the best fitting
multistage-cancer model as judged by the goodness-of-fitp-walue, is selected as the POD. In
accordance with U.S. EPA (2012b) guidance, BMDs and BMDLs associated with an extra risk
of 10% are calculated.
Model Predictions for Splenic Sarcomas or Osteosarcomas in Male F344/N Rats
Modeling was performed according to the procedure outlined above using BMDS for
combined incidence of splenic sarcoma or osteosarcoma in male F344/N rats based on the POD
(HEDs), and Table C-l summarizes the results. Both the 1- and 2-degree multistage-cancer
models provided adequate fit to this data set. The 2-degree model had the lower AIC and was
selected. The dose associated with 10% extra risk (BMDio) and its 95% lower confidence limit
(BMDLio) are 5.64914 and 3.69334 mg/kg-day, respectively.
Table C-l. BMD Modeling Results for Splenic Sarcoma or Osteosarcoma in Male F344/N
Rats Exposed to AyV-Dimethylaniline by Gavage 5 Days/Week for 2 Years"
Model
DF
X2
X2 Goodness-of-Fit
/>-Valueb
Scaled Residual
for Dose Group
AIC
BMDio
(mg/kg-d)
BMDLio
(mg/kg-d)
Multistage-cancer (1-degree)0
2
0.41
0.8147
0.194
30.655
6.96361
3.37669
Multistage-cancer
(2-degree)cd
2
0.04
0.9798
0.02
29.9582
5.64914
3.69334
•'N'TP ( 1989).
bValues <0.1 fail to meet conventional goodness-of-fit criteria.
Tower restricted to >1.
dSelected model. All models provided adequate fit to the data (selected model with the lowest AIC).
AIC = Akaike's information criterion; BMD = maximum likelihood estimate of the dose associated with the
selected benchmark response; BMDL = 95% lower confidence limit on the BMD (subscripts denote benchmark
response: i.e., io = dose associated with 10% extra risk); DF = degrees of freedom.
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Multistage Cancer Model, with BMR of 10% Extra Risk for the BMD and 0.95 Lower Confidence Limit for the BMDL
Multistage Cancer
Linear extrapolation -
0.2
0.15
o
it
<
c
o
tj
ra
0.05
BMDL
BMD'
0
1
2
3
4
5
dose
15:19 04/07 2016
Figure C-l. Multistage-Cancer 1-Degree BMD Model for Increased Splenic Sarcoma or
Osteosarcoma in Male Rats Administered AyV-Dimethylaniline Via Gavage
5 Days/Week for 103 weeks (NTP, 1989)
Text Output for Multistage-Cancer 1-Degree BMD Model for Increased Splenic Sarcoma
or Osteosarcoma in Male Rats (NTP, 1989)
Multistage Model. (Version: 3.4; Date: 05/02/2014)
Input Data File: C:/Users/bowens/BMDS2601/Data/msc_Dichotomous cancer_Opt.(d)
Gnuplot Plotting File: C:/Users/bowens/BMDS2601/Data/msc_Dichotomous
cancer_Opt.pit
Thu Apr 07 15:21:08 2 016
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
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Dependent variable = Effect
Independent variable = Dose
Total number of observations = 3
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 = 5 00
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) = 0.0174093
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
Interval
Variable
Limit
Background
Beta(1)
0.029961
Estimate
0
0.0151301
Std. Err.
NA
0. 00756688
NA - Indicates that this parameter has hit a bound
implied by some ineguality constraint and thus
has no standard error.
95.0% Wald Confidence
Lower Conf. Limit Upper Conf.
0.000299339
Analysis of Deviance Table
Model
Full model
Fitted model
Reduced model
Log(likelihood)
-13.9385
-14.3275
-18.3891
# Param's Deviance Test d.f. P-value
3
1 0.778028 2 0.6777
1 8.90131 2 0.01167
AIC:
30.655
Goodness of Fit
Scaled
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Dose
Est. Prob.
Expected
Observed
Size
Residual
0.0000
0.5000
5.0000
0.0000
0.0075
0. 0729
0.000
0.369
3.643
0.000
0.000
4.000
49.000
49.000
50.000
0. 000
-0.610
0.194
Chi^2 = 0.41
d.f. = 2
P-value = 0.8147
Benchmark Dose Computation
Specified effect = 0.1
Risk Type = Extra risk
Confidence level = 0.95
BMD = 6.963 61
BMDL = 3.37669
BMDU = 18.0513
Taken together, (3.37669, 18.0513) is a 90 % two-sided confidence
interval for the BMD
Cancer Slope Factor = 0.0296148
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Multistage Cancer Model, with BMR of 10% Extra Risk for the BMD and 0.95 Lower Confidence Limit for the BMDL
Multistage Cancer
Linear extrapolation -
0.2
0.15
o
0
it
<
c
.o
o
ra
0.05
BMDL
BMD'
0
1
2
3
4
5
dose
15:19 04/07 2016
Figure C-2. Multistage-Cancer 2-Degree BMD Model for Increased Splenic Sarcoma or
Osteosarcoma in Male Rats Administered AyV-Dimethylaniline Via Gavage 5 Days/Week
for 103 Weeks (NTP. 1989)
Text Output for Multistage-Cancer 2-Degree BMD Model for Increased Splenic Sarcoma
or Osteosarcoma in Male Rats (NTP, 1989)
Multistage Model. (Version: 3.4; Date: 05/02/2014)
Input Data File: C:/Users/bowens/BMDS2601/Data/msc_Dichotomous cancer_Opt.(d)
Gnuplot Plotting File: C:/Users/bowens/BMDS2601/Data/msc_Dichotomous
cancer_Opt.pit
Thu Apr 07 15:19:04 2016
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
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Dependent variable = Effect
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 = 5 00
Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008
Default Initial Parameter Values
Background = 0
Beta(l) = 0
Beta(2) = 0.00335177
Asymptotic Correlation Matrix of Parameter Estimates
( *** The model parameter(s) -Background -Beta(l)
have been estimated at a boundary point, or have been specified by
the user,
and do not appear in the correlation matrix )
Beta(2)
Beta(2) 1
Parameter Estimates
Interval
Variable
Limit
Background
Beta(1)
Beta(2)
0.00653786
Estimate
0
0
0.00330151
Std. Err.
NA
NA
0. 00165123
NA - Indicates that this parameter has hit a bound
implied by some ineguality constraint and thus
has no standard error.
95.0% Wald Confidence
Lower Conf. Limit Upper Conf.
6.51713e-005
Analysis of Deviance Table
Model
Full model
Fitted model
Reduced model
Log(likelihood) # Param's Deviance Test d.f.
P-value
-13.9385
-13.9791
-18.3891
0.0812992
8.90131
0.9602
0.01167
AIC:
29.9582
Goodness of Fit
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Dose
Est. Prob.
Expected
Observed
Size
Scaled
Residual
0.0000
0.5000
5.0000
0.0000
0.0008
0.0792
0.000
0.040
3.961
0.000
0.000
4.000
49.000
49.000
50.000
0. 000
-0.201
0. 020
Chi^2 = 0.04
d.f. = 2
P-value = 0.9798
Benchmark Dose Computation
Specified effect = 0.1
Risk Type = Extra risk
Confidence level = 0.95
BMD = 5.64914
BMDL = 3.69334
BMDU = 15.5498
Taken together, (3.69334, 15.5498) is a 90 % two-sided confidence
interval for the BMD
Cancer Slope Factor = 0.0270758
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APPENDIX D. REFERENCES
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