United States
kS^laMIjk Environmental Protection
^J^iniiil m11 Agency
EPA/690/R-06/004F
Final
10-19-2006
Provisional Peer Reviewed Toxicity Values for
Bifenox
(CASRN 42576-02-3)
Superfund Health Risk Technical Support Center
National Center for Environmental Assessment
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, OH 45268

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Acronyms and Abbreviations
bw
body weight
cc
cubic centimeters
CD
Caesarean Delivered
CERCLA
Comprehensive Environmental Response, Compensation and Liability Act

of 1980
CNS
central nervous system
cu.m
cubic meter
DWEL
Drinking Water Equivalent Level
FEL
frank-effect level
FIFRA
Federal Insecticide, Fungicide, and Rodenticide Act
g
grams
GI
gastrointestinal
HEC
human equivalent concentration
Hgb
hemoglobin
i.m.
intramuscular
i.p.
intraperitoneal
IRIS
Integrated Risk Information System
IUR
inhalation unit risk
i.v.
intravenous
kg
kilogram
L
liter
LEL
lowest-effect level
LOAEL
lowest-observed-adverse-effect level
LOAEL(ADJ)
LOAEL adjusted to continuous exposure duration
LOAEL(HEC)
LOAEL adjusted for dosimetric differences across species to a human
m
meter
MCL
maximum contaminant level
MCLG
maximum contaminant level goal
MF
modifying factor
mg
milligram
mg/kg
milligrams per kilogram
mg/L
milligrams per liter
MRL
minimal risk level
MTD
maximum tolerated dose
MTL
median threshold limit
NAAQS
National Ambient Air Quality Standards
NOAEL
no-ob served-adverse-effect level
NOAEL(ADJ)
NOAEL adjusted to continuous exposure duration
NOAEL(HEC)
NOAEL adjusted for dosimetric differences across species to a human
NOEL
no-ob served-effect level
OSF
oral slope factor
p-IUR
provisional inhalation unit risk
p-OSF
provisional oral slope factor
p-RfC
provisional inhalation reference concentration
p-RfD
provisional oral reference dose
PBPK
physiologically based pharmacokinetic
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ppb
parts per billion
ppm
parts per million
PPRTV
Provisional Peer Reviewed Toxicity Value
RBC
red blood cell(s)
RCRA
Resource Conservation and Recovery Act
RDDR
Regional deposited dose ratio (for the indicated lung region)
REL
relative exposure level
RfC
inhalation reference concentration
RfD
oral reference dose
RGDR
Regional gas dose ratio (for the indicated lung region)
s.c.
subcutaneous
SCE
sister chromatid exchange
SDWA
Safe Drinking Water Act
sq.cm.
square centimeters
TSCA
Toxic Substances Control Act
UF
uncertainty factor
l^g
microgram
[j,mol
micromoles
voc
volatile organic compound
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10-19-2006
PROVISIONAL PEER REVIEWED TOXICITY VALUES FOR
BIFENOX (CASRN 42576-02-3)
Background
On December 5, 2003, the U.S. Environmental Protection Agency's (EPA's) Office of
Superfund Remediation and Technology Innovation (OSRTI) revised its hierarchy of human
health toxicity values for Superfund risk assessments, establishing the following three tiers as the
new hierarchy:
1.	EPA's Integrated Risk Information System (IRIS).
2.	Provisional Peer-Reviewed Toxicity Values (PPRTV) used in EPA's Superfund
Program.
3.	Other (peer-reviewed) toxicity values, including:
~	Minimal Risk Levels produced by the Agency for Toxic Substances and Disease
Registry (ATSDR),
~	California Environmental Protection Agency (CalEPA) values, and
~	EPA Health Effects Assessment Summary Table (HEAST) values.
A PPRTV is defined as a toxicity value derived for use in the Superfund Program when
such a value is not available in EPA's Integrated Risk Information System (IRIS). PPRTVs are
developed according to a Standard Operating Procedure (SOP) and are derived after a review of
the relevant scientific literature using the same methods, sources of data, and Agency guidance
for value derivation generally used by the EPA IRIS Program. All provisional toxicity values
receive internal review by two EPA scientists and external peer review by three independently
selected scientific experts. PPRTVs differ from IRIS values in that PPRTVs do not receive the
multi-program consensus review provided for IRIS values. This is because IRIS values are
generally intended to be used in all EPA programs, while PPRTVs are developed specifically for
the Superfund Program.
Because science and available information evolve, PPRTVs are initially derived with a
three-year life-cycle. However, EPA Regions or the EPA Headquarters Superfund Program
sometimes request that a frequently used PPRTV be reassessed. Once an IRIS value for a
specific chemical becomes available for Agency review, the analogous PPRTV for that same
chemical is retired. It should also be noted that some PPRTV manuscripts conclude that a
PPRTV cannot be derived based on inadequate data.
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10-19-2006
Disclaimers
Users of this document should first check to see if any IRIS values exist for the chemical
of concern before proceeding to use a PPRTV. If no IRIS value is available, staff in the regional
Superfund and RCRA program offices are advised to carefully review the information provided
in this document to ensure that the PPRTVs used are appropriate for the types of exposures and
circumstances at the Superfund site or RCRA facility in question. PPRTVs are periodically
updated; therefore, users should ensure that the values contained in the PPRTV are current at the
time of use.
It is important to remember that a provisional value alone tells very little about the
adverse effects of a chemical or the quality of evidence on which the value is based. Therefore,
users are strongly encouraged to read the entire PPRTV manuscript and understand the strengths
and limitations of the derived provisional values. PPRTVs are developed by the EPA Office of
Research and Development's National Center for Environmental Assessment, Superfund Health
Risk Technical Support Center for OSRTI. Other EPA programs or external parties who may
choose of their own initiative to use these PPRTVs are advised that Superfund resources will not
generally be used to respond to challenges of PPRTVs used in a context outside of the Superfund
Program.
Questions Regarding PPRTVs
Questions regarding the contents of the PPRTVs and their appropriate use (e.g., on
chemicals not covered, or whether chemicals have pending IRIS toxicity values) may be directed
to the EPA Office of Research and Development's National Center for Environmental
Assessment, Superfund Health Risk Technical Support Center (513-569-7300), or OSRTI.
INTRODUCTION
Bifenox is not listed on IRIS (U.S. EPA, 2006), the HEAST (U.S. EPA, 1997a), or the
Drinking Water Standards and Health Advisories list (2004). The U.S. EPA Office of Pesticide
Programs (U.S. EPA, 1997b) derived a chronic RfD of 0.15 mg/kg-day for bifenox based on a
NOAEL of 15 mg/kg-day in a chronic study in dogs fed a dietary concentration of 600 ppm for
two years, and an uncertainty factor of 100 (10 for interspecies extrapolation and 10 for
susceptible populations). No occupational exposure limits have been established for bifenox by
ACGIH (2005), NIOSH (2006) or OSHA (2006). As a diphenyl ether herbicide, bifenox was
registered under FIFRA in 1975 and subsequently cancelled (U.S. EPA, 1994a, 1998). A
Pesticide Background Statement by U.S.D.A. (1987), a Summary of Toxicology Data by the
California Environmental Protection Agency's Department of Pesticide Regulation (CDPR,
1988), and the Office of Pesticide Programs' OPPIN database were consulted for data on
bifenox. No relevant documents were included in the CARA list (U.S. EPA, 1991, 1994b) or in
the Health Canada First or Second Priority List Assessments (Health Canada 2006a, 2006b).
ATSDR (2006), IARC (2006) and WHO (2006) have not reviewed the toxicity of bifenox.
Bifenox is not listed in the NTP (2006) management status report. In the fall of 2002, literature
searches were conducted for the period from 1965 to September 2002 to identify data relevant to
a carcinogenicity assessment for bifenox. The following databases were searched: TOXLINE
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(including NTIS and BIOSIS updates), CANCERLIT, MEDLINE, CCRIS, GENETOX, HSDB,
EMIC/EMICBACK, DART/ETICBACK, RTECS and TSCATS. Update literature searches
were conducted in November 2005 for the period of September 2002 to November 2005 in
TOXLINE special (including NTIS updates) and TOXCENTER (BIOSIS subfile). Databases
searched in November 2005 without date limitations included CCRIS, HSDB, GENETOX, and
RTECS. Additionally, updated searches of MEDLINE (plus PubMed cancer subset, which
replaces CANCERLIT) and Current Contents were performed for May 2005 to April 2006.
REVIEW OF PERTINENT DATA
Human Studies
No data were located regarding the oral or inhalation toxicity or carcinogenicity of
bifenox in humans.
Animal Studies
Oral Exposure
A four-week dietary study in rats was conducted by Huntingdon Research (1984) in order
to determine appropriate dietary bifenox levels to use in long-term studies. Six groups of
Sprague-Dawley rats (5/sex/group) were administered bifenox technical (purity and feed analysis
not stated) in the diet at concentrations of 0, 1000, 2000, 3500, 5000 or 10,000 ppm. The study
authors used observed values for body weight and food consumption to estimate mean doses of
0, 96, 190, 353, 495 or 904 mg/kg-day for male rats and 0, 105, 213, 372, 536 or 1045 mg/kg-
day for female rats. Daily observations were made of mortality, clinical signs, and water
consumption. Body weight, food consumption, and food utilization efficiency were measured
weekly. A gross, post-mortem examination was performed at the end of the study. Organ
weights (adrenals, brain, heart, kidneys, liver, ovaries, pituitary, spleen, tested, thyroid, and
uterus) were measured and histopathological examinations of the liver and kidneys were
performed.
Dose-related decreases in body weight gain were observed in both sexes, but the decrease
was statistically significant (24% lower than controls particularly during the initial week of
feeding) only in high-dose males. Food consumption in 10,000 ppm males was significantly
lower (20%) than controls, suggesting that decreased body weight gain in high-dose males may
have resulted from an unpalatable diet. No significant changes in food utilization were reported.
Hepatic effects were observed in both sexes. Liver weights (adjusted using body weight as a
covariate) were significantly increased in males at 10,000 ppm (24%) and in females at 1000,
5000, and 10,000 ppm (16-17%), but not at 3500 ppm. Gross hepatomegaly increased with dose
in male rats, as shown in Table 1. The trend was found to be significant using the Cochran-
Armitage test, while the incidence in the high-dose group was found to be significantly higher
than controls using Fisher's exact test (Table 1; tests performed for this review). No significant
differences were observed in females. Histopathology revealed minimal centrilobular hepatocyte
enlargement in 4/5 males at 10,000 ppm, which, for this review, was determined to be
significantly higher than controls using Fisher's exact test. Increase in liver weight and gross
hepatomegaly are consistent with an adaptive response to the high dose of bifenox and are not by
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themselves considered to be adverse. No statistically significant renal effects were observed
grossly or histologically. In this study, a free-standing NOAEL of 10,000 ppm (904 mg/kg-day)
was identified.
Table 1. Incidence of liver effects in male Sprague-Dawley rats given dietary bifenox for 4
weeks (Huntingdon Research, 1984)	
Effect
Exposure Level (p
pm)
0
1000
2000
35000
5000
10,000
Gross hepatomegalya
0/5
0/5
1/5
2/5
2/5
5/5 b
Centrilobular hepatocyte enlargement
0/5
ND
ND
0/5
0/5
4/5 b
a Significant (p<0.05) using Cochran Armitage trend test performed for this review
b Significant (p<0.05) using Fisher's exact test performed for this review
Huntingdon Research (1987a) exposed Sprague-Dawley rats to bifenox in the diet for two
years. Four groups of rats (50/sex/group) were fed diets containing 0, 500, 1580, or 5000 ppm of
bifenox technical (purity 98%) for 104 weeks. Satellite groups of 20 rats/sex/dose were also
included for blood sampling at intervals and for sacrifice at 52 weeks. Observed values for body
weight and food consumption were used by the study authors to estimate mean doses of 0, 19, 59
or 188 mg/kg-day for male rats and 0, 25, 77 or 252 mg/kg-day for female rats. During the
study, rats were checked twice daily for mortality. Observations for clinical signs were made
daily for 4 weeks, and then, in the absence of any clinical reaction to that point, weekly for the
remainder of the study. Body weights and food and water consumption were measured weekly,
from which food utilization efficiencies were calculated. Ophthalmoscopy was performed on 10
rats/sex/group at weeks 0, 52, and 102. Blood samples were taken from 10 rats/sex/group at
weeks 13, 27, 52 (again at week 53 for females, due to sampling problems on week 52), 77 and
103. Overnight urine samples were also collected from 10 rats/sex/group on weeks 14, 28, 52,
76, and 104. Hematological tests included packed cell volume (PCV), Hgb, mean corpuscular
volume (MCV), mean corpuscular hemoglobin concentration (MCHC), counts of RBCs, total
and differential white blood cells (WBCs), and platelets, thrombin time, and gross cell
morphology. Measured serum biochemistry parameters included levels of glucose, alkaline
phosphatase (ALP), aspartate-aminotransferase serum (AST) (reported by study authors as serum
glutamic-oxaloacetic transaminase), alanine-aminotransferase (ALT) (reported by study authors
as serum glutamic-pyruvic transaminase), albumin, globulin, total protein, blood urea nitrogen
(BUN), creatinine, sodium, potassium, calcium, inorganic phosphorus, chloride, and cholesterol.
Urinalysis parameters included urine volume, pH, specific gravity, protein concentration, and
qualitative measures of total reducing substances, glucose, ketones, bile pigments, urobilinogen,
and heme pigments. Urine samples were also observed microscopically for presence of
epithelial cells, mono- and polymorphonuclear leukocytes, erythrocytes, organisms, renal tubule
casts, sperm, and other abnormal constituents. At study termination of 52 (for satellite groups)
and 104 weeks, surviving rats were euthanized and given gross post-mortem examination of 37
tissue types. Adrenals, brain, heart, liver, kidneys, ovaries, pituitary, testes, and thyroid were
weighed. These and 22 other tissues, plus all nodules, tissue masses, and grossly abnormal
tissues, were examined for histopathology.
There were no dose-related trends in survival or clinical signs. Body weight gain and
food consumption were significantly reduced over the first 26 weeks of the study in the high-
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dose males, but subsequently recovered so that no differences from controls were found for the
study as a whole. There were no statistically significant findings in organ weight, hematology,
serum chemistry, urinalysis, or histopathology. Tumor incidence exhibited no statistical
significance or dose-related trend. In this study, a NOAEL of 5000 ppm (188 and 252 mg/kg-
day in males and females, respectively), was identified for chronic non-neoplastic effects. This
study is limited for use in assessing cancer effects, as the lack of adverse effects at all doses
indicates that the MTD was not achieved.
Charles River strain albino rats were given bifenox in the diet in a two year toxicity study
(IBT, 1976a). Four groups of rats (60/sex/dose) were fed diets containing 0, 60, 200 or 600 ppm
bifenox technical (purity not specified). For this review, values for body weight and food
consumption from the study report were used to estimate doses of 0, 3, 10 or 31 mg/kg-day for
male rats and 0, 4, 11 or 38 mg/kg-day for female rats. Daily observations were made for
mortality and abnormal reactions. Body weights were measured weekly for the first 3 months of
the study, and then monthly until study's end. Food consumption was measured and food
utilization calculated weekly for 10 rats/sex/group for the first 3 months, and then monthly
thereafter. Water consumption was measured on weeks 82-86 for 10 rats/sex/group. Blood
samples were taken from 10 rats/sex from control and 600 ppm groups (or all survivors, if less
than 10) at 3, 6, 12, and 24 months. Hematology measurements included counts of total and
differential leukocytes, erythrocytes, and platelets, as wells as hematocrit and Hgb levels. Serum
chemistry observations included ALP and ALT activities and glucose and BUN levels. Urine
was analyzed for albumin and glucose levels, pH, specific gravity, and examination of
microscopic elements. Upon unscheduled death, interim (10 rats/sex/group from the 0 and 600
ppm groups at 6 months of exposure) or terminal sacrifice, gross post-mortem exams were
performed. Organ weights were recorded for liver, kidney, spleen, heart, and gonads.
Histopathological exams of 27 different tissue types were conducted on all rats dying
prematurely (unless precluded by severe autolysis) and up to 10 rats/sex/group of terminal
survivors from the control and 600 ppm groups.
Mortality and clinical signs were similar across groups. Body weight gain was not
adversely affected in any group. There were no significant differences between groups for food
and water consumption. No statistically significant differences in hematology, serum chemistry,
or urinalysis were observed between controls and 600 ppm rats. Similarly, no significant
differences were observed in histopathological changes or neoplasm development between
control and 600 ppm groups. However, histopathology was performed on only 4-13 males/group
and 15-23 females/group of the possible 50 animals/group (not counting the 10 rats/group
sacrificed at 6 months). The high dose of 600 ppm (31 and 38 mg/kg-day for males and females,
respectively) was a NOAEL for non-neoplastic effects. This study is limited by the small
number of animals examined for chronic histopathology and carcinogenesis, lack of reporting for
compound purity, and as a cancer assay, failure to achieve a MTD.
A two-year oral toxicity and carcinogenicity study in B6C3Fi mice was conducted by
Litton Bionetics (1982). Four groups of mice (60/sex/dose) were fed diets containing 0, 50, 200
or 1000 ppm bifenox technical (purity 98.3%). Observed values for body weight and food
consumption were used by the study authors to estimate monthly intake of bifenox. These
monthly intakes were used in this assessment to estimate mean doses of 0, 7, 30 or 143 mg/kg-
day for male mice and 0, 9, 35 or 179 mg/kg-day for female mice over the course of the study.
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During the study, observations were made twice daily for mortality and weekly for clinical signs.
Body weights were measured weekly for the first 12 weeks and biweekly thereafter. Food
consumption was recorded every 4 weeks. Blood samples were collected from 10
mice/sex/group at 12 and 24 months. Hematology tests were performed, including measurement
of hematocrit, Hgb levels, and RBC, platelet, reticulocyte, and total and differential leukocyte
counts. Serum chemistry and urinalysis were not performed. At interim (12 months; 10
mice/sex/group) and terminal sacrifice, or following unscheduled death, liver, kidneys, brain,
heart and testes were weighed following complete gross necropsy. Histopathological exams
were performed on 30 tissue types, plus any other types exhibiting gross lesions at necropsy,
from all animals from all dose groups. Histopathological exams were also performed on some
additional tissues (the middle ear, paranasal sinuses, tongue, and oral and nasal cavities) from 10
rats/sex/group.
Mortality and clinical signs were unaffected by bifenox treatment. Body weights of all
treated groups of males were significantly less than controls by 7-9% at 24 months, but not in a
dose-related manner. Female body weights were not significantly different from controls.
Changes in food consumption did not appear to be dose-related. Hematology results were
unremarkable. In males, absolute, but not relative, brain, heart, and kidney weights were
significantly higher than controls (3, 11, and 6%, respectively) in the 200 ppm group at 24
months, while 1000 ppm males exhibited a transient increase in absolute and relative liver
weights (25% and 29%, respectively, at 12 months). These findings do not appear to be
toxicologically significant. In females, kidney weights increased in a dose-related manner, with
24 month absolute and relative increases of 13 and 9%, respectively, observed in the 200 ppm
group, and absolute and relative increases of 25 and 18% seen in the 1000 ppm group. Male
mice given 50, 200, or 1000 ppm exhibited statistically significant renal histopathology:
cytomegalic changes in renal tubule epithelium (focal hypertrophy, convoluted renal tubules),
classified as "minimal to mild" by the study pathologist (Table 2). No significant renal
histopathology was observed in females. No other significant, non-cancer histopathology was
observed. A LOAEL of 50 ppm (7 mg/kg-day) was identified for renal focal hypertrophy of
convoluted tubules in male mice. A NOAEL was not identified in this study.
Table 2. Incidence of focal hypertrophy, convoluted renal tubules in B6C3F1 mice
given dietary bifenox for 2 years (Litton Bionetics, 1982)	

Exposure level (ppm)

0
50
200
1000
Malesa
5/56
25/57b
40/55b
42/56b
Females
0/50
0/53
2/54
4/55
a Significant (p<0.05) using Cox's trend test
b Significant (p<0.05) using Fisher's exact test performed for this review
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The incidence of liver tumors (combined adenomas and carcinomas) was higher in males
and females at 1000 ppm than in controls (Table 3). However, the researchers noted that the
incidence of these tumors in treated animals was not unusually high for this age and strain of
mouse. Statistical analyses performed by the researchers, adjusting for survival because the 12-
month interim sacrifice animals were included in the tumor tabulation, showed no significant
pairwise increase or trend in males, and only a trend of marginal significance (p=0.041) by one
(Gehan-Breslow trend test) of three tests (including Cox's trend test and chi-square pair wise
comparison) in females. The researchers did not consider these findings to represent evidence of
oncogenicity.
Table 3. Liver tumor incidence in B6C3F1 mice given dietary bifenox for 2 years
(Litton Bionetics, 1982)	

Exposure
evel (ppm

Tumor Type
0
50
200
1000
Males




adenoma
5/56
3/57
8/55
7/56
carcinoma
4/56
9/57
6/55
10/56
combined adenoma and carcinoma
9/56
11/57
14/55
17/56
hemangiosarcoma
4/56
1/57
0/55
0/56
multifocal hemangiosarcoma
0/56
0/57
0/55
1/56
Females




adenoma
1/52
3/58
0/56
3/55
carcinoma
1/52
0/58
0/56
2/55
combined adenoma and carcinoma
2/52
3/58
0/56
5/55
hemangiosarcoma
0/52
0/58
0/56
1/55
metastatic hemangiosarcoma
0/52
0/58
0/56
1/55
IBT (1976b) exposed purebred beagle dogs to dietary bifenox for two years. Four groups
of dogs (6/sex/dose) were fed diets containing 0, 60, 200 or 600 ppm bifenox (purity not
reported). Using reference values for food intake and body weight for beagle dogs (U.S. EPA,
1988), the doses are estimated as 0, 1, 4 or 12 mg/kg-day for both sexes. Daily observations
were made for clinical signs. Weekly measurements were made of body weight and food
consumption. Food utilization was calculated for the first 13 weeks of the study. At 3, 6, 12, 18,
and 24 months, hematology, serum chemistry, and urinalysis were also performed. Hematologic
tests included hematocrit, Hgb, MCV, MCHC, and counts of RBCs, total and differential
leukocytes, and platelets. Serum chemistry measurements included levels of glucose, BUN,
ALP, ALT, AST, cholesterol, and total protein. Urinalysis included observation of albumin and
glucose levels, pH, specific gravity, and microscopic elements. At interim (2 dogs/sex/group at 6
months of exposure) and terminal sacrifice, gross post-mortem observations were made of all
major tissues and organs. Organ weights were obtained for liver, lungs, kidney, heart, brain,
spleen, gonads, and adrenal, thyroid, and pituitary glands. Histopathology was performed on 29
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tissue types. Ophthalmoscopy was performed just prior to terminal sacrifice. No statistical
analyses of study results were described or reported.
No mortality occurred and no unusual clinical signs were observed. Body weights, food
consumption and utilization, and observed hematological, serum chemistry, and urinalysis
parameters in treated dogs were deemed by the study authors to be comparable to controls and
unrelated to treatment. Ophthalmoscopy was normal for all dogs. Observed pathological lesions
were considered by the study pathologist to be normal disease occurrences and were not dose-
related. Thus, a free-standing NOAEL of 600 ppm (12 mg/kg-day) was identified for beagle
dogs.
Long-term toxicity of bifenox to beagle dogs was also studied by Huntingdon Research
(1986), who administered capsule doses of bifenox technical (purity 98%) to four groups of
beagle dogs (6/sex/group) for 52 weeks. Two dogs/sex/group were used for interim sacrifice at
26 weeks. Doses were 0 (empty capsule), 20, 145 or 1000 mg/kg-day. Daily observations were
made of clinical signs and food consumption. Body weights were measured weekly, while
ophthalmoscopy was performed and blood and urine samples collected on weeks 13, 26, and 52.
Observed hematological parameters included Hgb, PCV, MCV, MCHC, and counts of RBCs,
total and differential WBCs, platelets, and reticulocytes, RBC sedimentation rate, prothrombin
and activated partial thromboplastin time, and cell morphology. Serum chemistry tests included
measurements for levels of total protein, albumin, globulin, urea, creatinine, electrolytes,
cholesterol, glucose, ALP, ALT, AST, ornithine carbamoyltransferase (OCT),
gamma-glutamyltransferase (GGT), and total bilirubin. Urinalysis included observations of
urine volume, pH, protein, total reducing substances, glucose, ketones, bile pigments,
urobilinogen, heme pigments, and microscopic examination. Prior to interim (26 weeks) and
terminal sacrifice, bone marrow obtained via sternal puncture was examined for cellularity,
morphology, and cell distribution. Gross post-mortem exams were performed. Tissue weights
were measured for adrenals, brain, heart, kidneys, liver, lungs, pancreas, pituitary, spleen, testes
or ovaries, thymus, thyroids, and uterine or prostate. Histopathological examinations were
performed on 36 tissue types.
No mortality or treatment-related clinical signs were observed. There were no significant
differences between groups in body weights and gains, food consumption, or ophthalmoscopy.
RBC levels in males given 1000 mg/kg-day were significantly lower (15%) than controls at week
26 only, but were within the range normally expected for dogs of this age. Serum calcium levels
for all treated groups were significantly lower (4 to 7%) than controls at week 26. Males given
1000 mg/kg-day exhibited lower serum calcium levels before (4% lower) and throughout (up to
10%) lower) the study. Calcium values for all groups, however, were reported to be within
normal ranges. Males in the 1000 mg/kg-day group also had significantly (p< 0.05) elevated
mean ALT (75% higher) and OCT (83% higher) levels at week 52, with values for 3 of 4 dogs
exceeding the normal upper limits typically observed by the study authors (Table 4). Levels of
ALT and OCT in females were not treatment related, with animals in the 1000 mg/kg-day group
exhibiting week 52 ALT and OCT levels that were 14% higher and 4% lower, respectively, than
controls. No treatment-related effects on urinalysis parameters were observed. Gross post-
mortem examinations revealed no treatment-related effects. Terminal (52 week) liver weights,
adjusted for body weight, were significantly higher in high-dose males (30%) and females
(24%). Likewise, adjusted kidney weights were significantly higher in high-dose males (38%)
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and females (23%). However, histological changes observed for these, and all other tissues,
were not dose-related and were not useful for explaining relative weight increases for the liver
and kidneys. A LOAEL of 1000 mg/kg-day, and an associated NOAEL of 145 mg/kg-day, were
identified for significantly elevated serum levels of hepatic enzymes in male beagle dogs. Gross
and histological observations found no neoplasms or dose-related incidence of pre-neoplastic
lesions.
Table 4. Mean (±SD) serum ALT and OCT levels (mU/ml) in beagle dogs given
capsule doses of bifenox for 52 weeks (Huntingdon Research, 1986)	

Dose level (mg/kg-day)

0
20
145
1000
males

ALT
32 ±7.6
42 ± 15.9
36 ±2.4
56 ± 18.7a
OCT
5.9 ± 2.4
7.8 ± 1.0
7.6 ±0.9
10.8 ± 3.7a
females

ALT
29 ± 5.4
28 ±3.1
26 ±4.6
33 ± 5.6
OCT
7.2 ± 1.6
7.3 ± 1.7
7.0 ± 1.4
6.9 ± 1.0
a Significant (p<0.05) using William's test
IBT (1977) conducted a three-generation reproductive toxicity study in rats. Four groups
of CD strain Charles River albino rats (10 males and 20 females per group) and their progeny
were administered bifenox technical (purity 97.2%) in the diet at concentrations of 0, 20, 60 or
200 ppm. Using reference factors for food consumption and body weight in U.S. EPA (1988),
the doses are estimated to be 0, 2, 6 or 20 mg/kg-day for males and 0, 2, 7 or 23 mg/kg-day for
females. F0 mating sets (1 male and 2 females) from each dose group were allowed to produce 2
litters, the first of which were sacrificed and discarded at weaning (day 21 post-partum) while the
second were pooled with other litters within dose group to select Fi parents (10 males and 20
females per group). This was repeated for F2 progeny/parents. The study was terminated with
the sacrifice of the F3 progeny at weaning. Exposure duration comprised a pre-mating period
(100 days), up to 3 attempts of 1st round of conception (up to 30 days total), gestation (21 days),
a mating break period, if first mating was successful (10 days), 2nd round of conception (up to 30
days total), 2nd gestation (21 days), and pup rearing to weaning (21 days), for a total of up to 233
days for F0, Fi, and F2 parents. Daily observations were made for mortality, clinical signs, and
abnormal behavior; however, body weights were taken weekly. Fecundity, male and female
fertility, gestation length, lactation performance, survival, and live birth indices were also
measured. Gross post-mortem examinations were performed on animals dying early. However,
necropsies were not performed on all pups and adults; 8 males and females from pooled litters of
each group were examined for gross pathology and organ weight. In addition, 5 males and
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females from the control and 200 ppm groups, as well as all animals exhibiting grossly visible
pathology at necropsy, were subjected to complete microscopic pathology exams.
No significant differences in mortality or clinical observations were found. Significantly
higher paternal body weights (up to 24%) were observed in the 200 ppm group, compared to
controls, in weeks 4 to 11, but not at termination; the study authors reported that the increased
body weights were within the range normally observed in this strain of rat. Statistically
significant changes in organ weight for liver, spleen, and gonads observed in 60 and 200 ppm
parents were seemingly random for generation and organ type. Fi and F2 males given 200 ppm
had 16 and 17% higher gonad weights, respectively, than controls. F2 females given 200 ppm
had 24%) lower absolute liver weights than controls, while F2 males and females given 60 ppm
had 15 and 21% lower relative liver weights, respectively. F0 males given 60 ppm and Fi males
given 200 ppm had 43 and 55% higher spleen weights, respectively, while relative weights were
32% and 21% higher for F0 and Fi males, respectively, given 200 ppm. These organ weight
changes were not considered treatment-related. No significant differences in histopathology
were observed. Reduced pup survival at weaning (postnatal day 21) was reported in the high-
dose group of the F3 generation. In one pooled litter of F3 progeny (second mating) from the 200
ppm dose group, viable pups surviving to day 21 was 12% (12/98), or 1.0 pups/dam, compared
with 57%) (40/70), or 5.7 pups/dam for controls. However, survival indices were not different
from controls for the pooled F3 litter from the first mating of the 200 ppm group. Nor were
effects on viability observed in any of the Fi or F2 litter groups at 200 ppm, or in any of the 20
and 60 ppm litter groups of any generation. Therefore, the reduced viability of pups in second
mating F3 litters at 200 ppm was considered not to be treatment-related. The high dose of 200
ppm (20 and 27 mg/kg-day for males and females, respectively) was identified as a NOAEL for
reproductive effects in rats.
CDPR (1988) summarized a rabbit teratology study conducted by Hazleton Labs (1979).
Bifenox (purity 98.3%) was administered by gavage in corn oil to groups of 15 artificially
inseminated New Zealand White rabbits at doses of 0, 12.5, 25 or 50 mg/kg-day on gestational
days (GD) 6-19. Maternal mortality and clinical signs (depression, prostration, tremors, fecal
and urine stains, nasal or eye discharge, soft feces, wheezing, cyanosis, ataxia, dyspnea and
hunched appearance) were reported in all dose groups. No developmental effects were reported
at any dose. On the basis of the available study summary, there is not enough information
available to adequately identify a maternal or developmental NOAEL or LOAEL.
In a second rabbit teratology study conducted by Hazleton Labs (1986), bifenox technical
(purity 97%) was administered by gavage in 0.5% carboxymethylcellulose to artificially
inseminated New Zealand White rabbits (16/group) at doses of 0, 5, 50, 160, 500 and 1000
mg/kg-day on GD 6-19. Observations were made during gestation for mortality, clinical signs,
body weight, and food consumption. In the event of signs of abortion or premature delivery,
does were euthanized and subjected to post-mortem examination, with additional observations
made for implantation sites and resorbed and abnormally developing fetuses. Does surviving to
term were sacrificed and subjected to post-mortem gross examination. Fetuses were examined
viscerally for gross pathology and skeletal abnormalities. Gross pathologic examination of the
fetuses demonstrated no abnormalies of viscera and musculo-skeletal systems.
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Maternal mortality incidence was 14/16 (88% mortality by GD 25) in the 500 mg/kg-day
group and 16/16 (100% mortality by GD 22) in the 1000 mg/kg-day group. Transient, but
significant, body weight decreases of as much as 23% were observed in the 500 mg/kg-day
group on GD 11-20. Food consumption in this group was 50-85%) less than controls on GD 5-20
and 24-29. Likewise, body weights for the 1000 mg/kg-day group were decreased by as much as
41% on GD 8-20, while food consumption was 88% lower than controls on GD 6-8 and 100%
less on GD 9-20. Clinical signs observed after treatment of >500 mg/kg-day included
hypoactivity, ashen or pale appearance, body tremors and ataxia. The only unusual finding from
gross pathological observation was hair and/or compound-like material found in the stomachs of
prematurely dying does. Fetal effects could not be evaluated in the highest dose group because
of complete maternal mortality. No dose-related developmental effects, including spontaneous
abortion, were noted in the other treatment groups. In this rabbit study, a maternal FEL of 500
mg/kg-day, with an associated NOAEL of 160 mg/kg-day, was identified for increases in
mortality and clinical signs in does. The developmental NOAEL was 500 mg/kg-day; due to
maternal mortality, the 1000 mg/kg-day dose was not evaluated for developmental toxicity. This
study found no developmental effects of bifenox in rabbits, even at dose levels highly lethal to
the does.
A developmental toxicity study in rats was conducted by IBT (1972). In this study,
mated albino rats (17-18/group) were administered bifenox technical (purity 99%) by gavage in
corn oil at doses of 0, 50 and 100 mg/kg-day on GD 6-15. Dams were observed daily for
mortality and clinical signs. Body weights were measured on GD 6, 9, 12, 15, and 20. At
sacrifice on GD 20, observations were made for fetal swellings, implantation sites, uterine
abnormalities, number of corpora lutea, viable fetuses, fetal weight, sex ratio, skeletal
abnormalities, and gross internal and external abnormalities. No mortality or clinical signs were
observed in dams, and maternal body weights were comparable throughout the study. Maternal
uterine abnormalities were not found in any group. No treatment-related differences were found
for any fetal parameters. The highest dose of 100 mg/kg-day was a NOAEL for both maternal
and developmental toxicity.
CDPR (1988) summarized a rat teratogenicity study conducted by Huntingdon Research
(1981a). Mated Sprague-Dawley rats (12/group) were administered bifenox (purity assumed to
be 100%) by gavage in 1% methylcellulose at doses of 0 or 100 mg/kg-day on gestational GD 6
to postpartum day (PD) 21. A slight, but not statistically-significant decrease in relative and
absolute liver weights was observed in treated dams, but no developmental toxicity was
observed. In the absence of methodology description and data from the study, insufficient
information was available to derive a NOAEL or LOAEL.
CDPR (1988) summarized a second rat teratogenicity study conducted by Huntingdon
Research (1981b) in which mated Sprague-Dawley rats (24/group) were given diets containing 0,
500 or 1000 ppm of bifenox on GD 6 to PD 21. Using the reference body weight and the
equations for food consumption (U.S. EPA, 1988), the doses are calculated as 0, 10, and 20
mg/kg-day. No significant effects were observed in dams or offspring. As with the prior rat
study (Huntingdon Research, 1981a), the absence of actual study method descriptions and data
precluded the derivation of a NOAEL or LOAEL.
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A third rat teratogenicity study was conducted by Huntingdon Research (1987b) in which
bifenox technical (purity 98%) was administered by gavage in 1% aqueous methylcellulose to
mated Sprague-Dawley rats (25/group) at doses of 0, 225, 900 and 3600 mg/kg-day on GD 6-15.
Animals were observed daily for mortality, clinical signs, and food consumption. Observations
of water consumption began on GD 13. Body weights were measured on GD 1, 3, 6, 10, 14, 17,
and 20. At GD 20, dams were sacrificed and internal organs examined for gross pathology.
Ovaries and uteri were examined for number of corpora lutea, number and distribution of live
and dead fetuses, fetal weight, and fetal external, internal, and skeletal abnormalities.
One dam from the 3600 mg/kg-day group died on GD 12 and 3 others were sacrificed in
extremis on GD 8, 13, or 14. Post-mortem observations suggested that at least 3 of the 4 cases
may have resulted from difficulties in dosing the highly viscous suspension. Occasional
salivation, clear ocular discharge, lethargy, hunched posture, and patchy hair loss were seen in
dams given 3600 mg/kg-day. While food consumption was transiently decreased in dams given
3600 mg/kg-day (10% lower than controls on GD 6-10), body weights were comparable across
groups. Water consumption was also similar across groups. No significant developmental
effects were observed at any dose. Thus, a maternal FEL of 3600 mg/kg-day, with an associated
NOAEL of 900 mg/kg-day, was identified for increased mortality and clinical signs of toxicity in
dams. The highest dose, 3600 mg/kg-day, was identified as a developmental NOAEL.
Therefore, this study found that bifenox did not produce developmental effects in rats even at
doses highly toxic to the dams.
Francis (1986) conducted a developmental study in Sprague-Dawley rats in which two
groups of pregnant rats (6-10 per group) were given 0 or 100 mg/kg of bifenox by gavage in corn
oil on GD 9, 10, 11 or 12. Litters were raised to weaning and observed daily for mortality. All
pups were examined for the appearance of 'bloody tears,' a sign of inhibited Harderian gland
development or respiratory disease. Bifenox had no significant effect on pups. The incidence of
'bloody tears' was 0% in control litters and 2.6% (1 pup) in treated pups on GD 10. Thus, a
NOAEL of 100 mg/kg-day was identified for developmental toxicity in rats. There was
insufficient data to identify a maternal NOAEL or LOAEL. Of note, rats exposed to nitrofen, a
structural analog of bifenox, on GD 10 exhibited no statistically significant effect on pup
survival; however, all litters exhibited 'bloody tears', resulting in an overall pup incidence rate of
67.7%.
In another experiment reported in the same paper, Francis (1986) gave gavage doses of 0,
10 or 100 mg/kg-day of bifenox (purity >99%) in corn oil to pregnant Swiss mice (7-13 per
group) on GD 5-14. At termination on GD 18, observations were made of the number of live
and resorbed fetuses and external fetal malformations. Changes in maternal body weight gain
were not reported. No significant differences were seen in the number of litters per mated
female or the number of live or resorbed fetuses per litter. Two exencephalic pups were found in
a single bifenox-treated litter; however, the associated dose level was not reported. This defect
did not occur in controls. Results of a later study (Francis et al., 1999) suggest that the
exencephaly observed in this study was not related to treatment. Therefore, the high dose of 100
mg/kg-day was identified as a NOAEL for developmental toxicity in mice. The study did not
provide enough information to identify a maternal NOAEL or LOAEL.
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Francis et al. (1999) compared the maternal and developmental toxicity of eleven
halogenated 4'-nitrodiphenyl ethers in mice. Mated female CD-I mice were treated with 0, 250,
500, 750 or 1000 mg/kg-day of bifenox by gavage in corn oil on GD 6-15. The number of mated
dams given bifenox, in order of increasing dose, was 6, 7, 2, and 12, though the rationale for
these group sizes was not reported. One hundred fifty-three mated dams were in the control
group. Dams were evaluated for clinical signs, weight gain between GD 6-16, mortality, number
of litters born per group, the number of pups per mated female. Mean pup weights were reported
for each group for PD 1, 5, and 15. At weaning (PD 30), 3 male and 3 female pups from each
litter (except for the small 750 mg/kg-day group) were individually examined for body weight
and the weight of the Harderian glands; regression analysis was used to evaluate dose effects on
Harderian gland weight using sex, age and body weight as covariables.
The authors did not report mortality incidence. Bifenox had no significant effect on
weight gain in dams that carried litters to term; weight gain results were not reported for dams
given 750 mg/kg-day. The authors reported that for the diphenyl ethers in general, an increase in
clinical signs (hunched posture, ruffled fur and vaginal bleeding) was correlated with a reduction
in the number of litters born to treated females. The inference from prenatal mortality data
provided for bifenox (Table 3 in the study report) is that these effects were observed in dams
treated with bifenox at or above 750 mg/kg-day. Increases in prenatal losses of entire litters
were dose-related; the incidence of prenatal litter loss was 10/153 in controls and 0/6, 1/7, 2/2
and 9/12 for the groups exposed to the lowest-to-highest doses of bifenox, respectively. For this
review, statistical analysis of the incidence of litters lost prior to birth found a significant trend
using the Cochran-Armitage test, and significant differences between controls and the 750 and
1000 ppm groups using Fisher's exact test. Bifenox had no statistically significant effect on the
postnatal survival or body weight of litters, although both parameters were slightly reduced at the
highest dose. In individually examined pups, the weight of the Harderian gland was slightly
lower at the highest dose, but the difference was not statistically different from controls. This
study is limited by its reporting deficiencies, necessitating extrapolation from the general
comments on the toxicity of the tested diphenyl ethers. On this basis, the maternal and
developmental NOAELs were 500 mg/kg-day and the LOAELs were 750 mg/kg-day for prenatal
litter loss and the (presumed) increase in clinical signs associated with prenatal litter loss.
Bifenox appears not to be a specific developmental toxicant because adverse effects were
observed at maternally toxic doses and no significant postnatal effects were noted in litters
surviving to term.
Inhalation Exposure
An acute inhalation LC50 of greater than 200 mg/L was reported for technical grade
(96%) bifenox in rats (U.S.D.A., 1987). No relevant data were located regarding the toxicity of
bifenox to animals following subchronic or chronic inhalation exposure.
Other Studies
Acute oral LD50 values for technical grade bifenox (purity >96%) were reported to be
greater than 5000 or 6400 mg/kg for rats (U.S.D.A., 1987) and 4556 mg/kg for mice (RTECS).
Eli Lilly & Co. (1981a) reported no mortality in mice receiving single oral doses as high as 9700
mg/kg. Differences between studies in lethality may be related to choice of dose vehicle. While
10%) acacia was used as the vehicle in the Eli Lilly & Co. studies (1981a,b,c), the vehicles
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associated with the LD50 values in U.S.D.A. (1987) and RTECS were not reported. No toxicity
was observed in mice receiving 500 mg/kg, but doses between 700 and 9700 mg/kg caused
generalized weakness of the limbs (Eli Lilly & Co., 1981a,b,c). The effect was transient,
dissipating by the second hour after dosing in mice dosed with 700 or 1000 mg/kg and by the
second day in mice dosed with 2750-9700 mg/kg.
Topical application of bifenox to mouse dams during gestation (Francis, 1986) resulted in
effects similar to those seen in the oral mouse developmental study (Francis et al., 1999).
Topical doses of 0, 1, 2 or 5 mg of bifenox dissolved in xylene were applied to the back skin of
pregnant Swiss mice on GD 5-14; daily doses were reported as 0, 30-45, 60-90 or 150-200
mg/kg-day, respectively. The study authors reported that an apparent decrease in survival of
bifenox-treated mice resulted from the complete loss of one litter in the highest dose group.
Bifenox had no statistically significant effect on pup weight, the number of live pups at birth or
at weaning, or the weight of the Harderian gland in pups. In parallel groups, nitrofen treatment
at the highest dose significantly increased pup mortality, and reduced the mean weight of pups
from postnatal day 1 to weaning, as well as the weights of the Harderian glands and eyes.
Several investigators used in vitro assays to evaluate the ability of bifenox to induce
mutagenicity, genotoxicity, and endocrine disruption. In vitro genotoxicity studies on bifenox
reported generally negative results, with or without metabolic activation (unless otherwise noted,
all studies reviewed here used both test conditions). Bifenox was not mutagenic to Salmonella
typhimurium strains TA1535, TA1537, TA1538, TA98, or TA100 (American Biogenics Corp.,
1986; Hokky Kagaku Kogyo Laboratory, 1982; EG&G Mason Research Institute, 1979, as
described in CDPR, 1988; Eisenbeis et al., 1981; Kubo et al. 2002), Escherichia coli strains WP2
her (U.S.D.A, 1987) or WP2 uvrA (Hokky Kagaku Kogyo Laboratory, 1982 as described in
CDPR, 1988), or to Saccharomyces cerevisiae (Plewa et al., 1984). In tests with two strains of S.
typhimurium that contain high nitroreductase activity, bifenox was not mutagenic to YG1021,
but was, with activation, slightly mutagenic in YG1026 (3 revertants per mg) (Oguri et al.,
1995). Mutagenicity was also seen in S. typhimurium strains YG1024 and 1026 (with metabolic
activation), but not in YG1021, 1029, 3003, and 7108, with or without metabolic activation
(Tanaka et al., 2002). Bifenox was not mutagenic in Chinese hamster ovary cells in vitro
(Pharmakon Res. Intl., as described in CDPR, 1988). No increase in chromosomal aberrations
was observed in cultured Chinese hamster ovary cells treated with bifenox (American Biogenics
Corp., as described in CDPR, 1988) or in cultured bovine peripheral lymphocytes treated with
bifenox as the commercial herbicide Modown (Sivikova and Dianovsky, 1999), although dose-
related increases in the sister chromatid exchange and decreases in mitotic and proliferation
indices were exhibited, with significant reductions occurring at the highest concentrations (250-
1000 |ig/ml). Without metabolic activation, bifenox did not induce unscheduled DNA synthesis
in cultured primary rat hepatocytes (Litton Bionetics, as described in CDPR, 1988). Bifenox
gave negative results in a cell transformation assay using C3H/10T0T1/2 cells without metabolic
activation (EG & G Mason Res. Inst., as described in CDPR, 1988).
In vivo, bifenox was not clastogenic to bone marrow of male Sprague-Dawley rats that
received single gavage doses as high as 1500 mg/kg (Mobil Environ. Health Sci. Lab., as
described in CDPR, 1988). In mice that received two intraperitoneal injections of bifenox 24
hours apart, no evidence of micronucleus formation was observed in males at doses as high as
1440 mg/kg/injection, whereas an increase in micronucleus formation was observed in females at
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doses of 480 or 720 mg/kg/injection (1440 mg/kg was lethal to females) (Borriston Labs, Inc., as
described in CDPR, 1988).
In a screening of pesticides to test for androgenic receptor activity using an in vitro
reporter gene in Chinese hamster ovary cells, Kojima et al. (2004) found bifenox to be negative
for estrogenic activation via the human estrogenic receptor a and P genes, but positive for
inhibition of human androgenic receptor transcriptional activity when induced by 5a-
dihydrotestosterone. The authors suggest that this may implicate bifenox as an endocrine
disruptor.
DERIVATION OF PROVISIONAL SUBCHRONIC AND CHRONIC RfDs
FOR BIFENOX
No human data are available to derive a provisional subchronic or chronic RfD for
bifenox. Animal studies describe the effects of bifenox administered orally in the diet or as
bolus doses to mice, rats, dogs, and rabbits. Kidney and liver effects appear to be the most
sensitive endpoints (Table 5). Rats exposed to 904 mg/kg-day in the diet for 4 weeks
(Huntingdon Research, 1984) exhibited significant increases in liver weights and liver
histopathology (centrilobular hepatocyte enlargement); however, these are considered adaptive
responses to chemical exposure rather than toxic effects. Beagle dogs given 1000 mg/kg-day by
capsule for 1 year (Huntingdon Research, 1986) exhibited significantly increased blood levels of
ALT (75% higher than controls) and OCT (83% higher than controls), indicative of liver
toxicity, as well as increased liver and kidney weights. Two-year dietary exposure studies in rats
(IBT, 1976a; Huntingdon Research, 1987a), dogs (Huntingdon Research, 1987a), and mice
(Litton Bionetics, 1982) did not report adverse liver effects; however, exposure levels reported in
these studies were notably lower than 1000 mg/kg-day (252 mg/kg-day in female rats in
Huntingdon Research, 1987a was the maximum dietary level). Kidney effects were observed at
chronic doses as low as 7 mg/kg-day in mice, including renal histopathology (renal tubule
cytomegalic changes without progression to hyperplasia and necrosis) in males and, at the higher
doses, increased kidney weights in females.
A number of developmental toxicity studies in rats, mice, and rabbits suggest that the
neonate is less sensitive than the mother to bifenox toxicity (Table 6). Gestational exposure of
rats (Francis, 1986; IBT, 1972) and mice (Francis, 1986) to gavage doses of 100 mg/kg-day did
not result in maternal (results not reported in all studies) or developmental toxicity. Frank
maternal effects, including mortality, were observed in rabbits given 500 or 1000 mg/kg-day by
gavage from GD 6-19 (Hazelton Labs, 1986), rats given 3600 mg/kg-day from GD 6-15
(Huntingdon Research, 1987b), and are presumed to have occurred in mice given 750 or 1000
mg/kg-day from GD 6-15 (Francis et al., 1999), although poor reporting of maternal toxicity in
this study makes interpretation uncertain. No fetal effects occurred in the rat or rabbit studies.
Full litter loss was observed in the mouse study, but this may reflect a maternal, rather than fetal
effect. In any event, the increase in full litter loss was only seen at maternally toxic doses. A 3-
generation reproduction study in rats given bifenox in the diet (IBT, 1977) found reduced 21-day
survival of F3 pups of the pooled litter from the second mating in the high-dose group given 20
mg/kg-day. However, no effect on pup viability was seen in the corresponding F3 pooled litter
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Table 5. Non-cancer effects and effect levels identified from studies of oral (dietary and
capsule dosing) bifenox exposure to animals	
Source
Species
Exposure
duration /
sub-route
NOAEL
mg/kg-
day
LOAEL
mg/kg-
day
Effect
Huntingdon
Research, 1984
rats
4 weeks, dietary
904
ND
adaptive increases in liver
weight and centrilobular
hepatocyte enlargement
IBT, 1977
rats
up to 233 days
(multigeneration),
	dietary	
20
ND
no dose-related findings
IBT, 1976a
rats
2 years, dietary
31
ND
no dose-related findings
Huntingdon
Research, 1987a
rats
2 years, dietary
188
ND
no dose-related findings
Litton
Bionetics, 1982
mice
2 years, dietary
ND
renal tubule cytomegalic
changes in males
Huntingdon
Research, 1986
dogs
1 year, capsule
145
1000
increased serum ALT and
OCT levels in males
IBT, 1976b
dogs
2 years, dietary
12
ND
no dose-related findings
ND = Not determined
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Table 6. Non-cancer effects and effect levels identified from developmental studies of oral
gavage exposure to animals
Source
Species
Exposure
duration /
sub-route
NOAEL
mg/kg-day
LOAEL
mg/kg-day
Effect
Francis et al.,
1999
mice
GD 6-15,
gavage
maternal: 500
fetal: 500
maternal: 750
fetal: 750
clinical signs
(presumed) in dams;
prenatal litter loss
Francis, 1986
mice
GD 5-14,
gavage
maternal: ND
fetal: 100
maternal: ND
fetal: ND
no dose-related fetal
findings; inadequate
reporting of maternal
effects
Huntingdon
Research,
1987b
rats
GD 6-15,
gavage
maternal: 900
fetal: 3600
maternal:
3600
fetal: ND
maternal mortality
(FEL) and clinical
signs; no fetal effects
Francis, 1986
rats
GD 9,10,11
or 12,
gavage
maternal: ND
fetal: 100
maternal: ND
fetal: ND
no dose-related fetal
findings; inadequate
reporting of maternal
effects
IBT, 1972
rats
GD 6-15,
gavage
maternal: 100
fetal: 100
maternal: ND
fetal: ND
no dose-related
maternal or fetal
findings
Hazleton
Labs, 1986
rabbit
GD 6-19,
gavage
maternal: 160
fetal: 500
maternal: 500
fetal: ND
maternal mortality
(FEL), clinical signs,
and reductions in
food consumption
and body weight; no
fetal effects
GD = gestation day , ND = Not determined, FEL = frank effect level
group from the first mating, or in the Fi or F2 generations at this same dose, or in the lower dose
groups. Therefore, this effect was considered not to be treatment-related (Table 5).
Subchronic RfD
Studies considered in derivation of the subchronic RfD include the 4-week study in rats,
the one-year study in dogs (considered a subchronic duration for this species, since one year is
approximately 10% of a lifetime in dogs), and the reproductive and developmental studies. As
discussed above, the developmental studies demonstrated that the fetus is not a sensitive target
for bifenox independent of maternal toxicity. The frank maternal toxicity seen in these studies
was probably a by-product, at least in part, of the bolus dosing used in these studies. Frank
effects were accompanied by observations of compound-like material in the stomach (Hazelton
Labs, 1986), which may be a result of gavage dosing of bifenox suspension. The dietary
administration used in the systemic toxicity and multigeneration studies more closely
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corresponds to the expected human environmental exposures than the bolus dosing used in the
developmental studies. Among the dietary studies, only the one-year dog study identified a
critical effect and effective levels. Effects in the multigeneration study (IBT, 1977) were
considered not to be treatment-related, while those in the 4-week rat study (Huntingdon
Research, 1984) were not clearly adverse.
The 52-week dietary exposure study in beagle dogs (Huntingdon Research, 1986) was
selected as the principal study for derivation of a subchronic RfD since it identified a LOAEL of
1000 mg/kg-day, with an associated NOAEL of 145 mg/kg-day, based on clear, treatment-
related elevations of the liver enzymes ALT and OCT in serum of male beagle dogs. Benchmark
dose analysis, using the Benchmark Dose Modeling Software (BMDS), version 1.3.2, was
performed on the ALT and OCT data from the male dogs to estimate doses (BMD) and lower
bounds on the 95% confidence interval (BMDL) associated with a benchmark response (BMR)
of 1 standard deviation from controls, as recommended by U.S. EPA (2000) for continuous data.
However, the variances across dose groups were not constant and the power model built into the
BMDS was not able to adequately fit the variance data for either data set. Because the data
could not be modeled satisfactorily, derivation of the subchronic provisional RfD is based on the
observed LOAEL of 1000 mg/kg-day and NOAEL of 145 mg/kg-day for significant increases in
the serum levels of the liver enzymes ALT and OCT in male beagle dogs.
The provisional subchronic RfD of 1 mg/kg-day is derived by dividing the NOAEL of
145 mg/kg-day for increased serum levels of hepatic enzymes in males identified in the 52-week
capsule dosing study in dogs (Huntingdon Research, 1986) by a composite uncertainty factor
(UF) of 100, as follows:
Subchronic p-RfD = 145/UF
= 145 mg/kg-day / 100
= 1 mg/kg-day
The composite UF includes a factor of 10 for extrapolation from animals to humans and
10 for inter-individual variability. No uncertainty factor for database deficiencies was applied
due to the relatively complete database for the chemical, including a multigeneration
reproduction study and developmental toxicity studies in multiple species.
Confidence in the critical study is medium. The study investigated an adequate array of
endpoints, but group sizes were small. Dose-related increases in serum levels of two liver
enzymes in male dogs provided reasonable evidence of hepatotoxicity. However, the magnitude
of the observed changes was somewhat less than the 2-3 fold increase conventionally considered
to represent clinical significance for these effects, and no corresponding histopathological lesions
were detected. Further, comparable changes were not found in females. Confidence in the
database is medium-to-high. Extensive clinical and histopathology data were available from
well-conducted studies in rats and dogs, but several studies did not include dose levels high
enough to observe effects. In addition to systemic toxicity studies, the database includes
developmental toxicity studies in rats, mice and rabbits and a multigeneration reproduction study
in rats. Overall confidence in the provisional subchronic RfD is medium.
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Chronic RfD
Studies of toxicity from chronic bifenox exposure have been performed in mice, rats, and
dogs. The studies in rats and dogs failed to find any effects at dietary doses up to 188 mg/kg-day
in rats (IBT, 1976a; Huntingdon Research, 1987a) and 12 mg/kg-day in dogs (IBT, 1976b). The
mouse study (Litton Bionetics, 1982) found renal effects at 7 mg/kg-day and above in males
(minimal to mild focal hypertrophy of convoluted renal tubules) and at 35 mg/kg-day and above
in females (increased absolute and relative kidney weights). Minimal to mild focal hypertrophy
of convoluted renal tubules was also occasionally noted in female mice. The incidence of renal
histopathology in male mice is clearly dose-related and aNOAEL was not identified (Table 2).
The only other report of renal effects in the literature was an increase in kidney weight in the
one-year dog study at a dose of 1000 mg/kg-day, with no effect at 145 mg/kg-day (Huntingdon
Research, 1986). Developmental and reproductive effects have been shown not to be sensitive
endpoints for bifenox, as discussed above.
Based on these data, mice appear to be the most sensitive species, and the kidney the
most sensitive endpoint with chronic dietary exposure. The 2-year mouse study of Litton
Bionetics (1982) was chosen as the principal study for derivation of a chronic RfD because it
identified the lowest LOAEL of 7 mg/kg-day in the diet for histopathological renal changes over
the lifespan of the most sensitive test species. A NOAEL was not identified. Dose-response
modeling was performed using the BMDS (Version 1.3.2) and a benchmark response (BMR) of
10% extra risk. All available dichotomous models were fit to the data and the best fit was
determined using guidelines described in U.S. EPA (2000). The results of the BMDS modeling
are summarized in Appendix A. None of the models produced adequate fits using data from all
four exposure levels. By dropping the highest exposure level, as described in U.S. EPA (2000),
an adequate fit was achieved by the log-logistic model, with estimated values of 1.3 and 0.9
mg/kg-day for the BMDio and BMDLio, respectively.
The provisional chronic RfD of 0.009 mg/kg-day is derived by dividing the BMDLio of
0.9 mg/kg-day for renal effects identified in a 2-year dietary exposure study in mice (Litton
Bionetics, 1982) by a composite UF of 100 as follows:
Chronic p-RfD = BMDLio / UF
= 0.9 mg/kg-day / 100
= 0.009 or 9E-3 mg/kg-day
The composite UF includes a factor of 10 for extrapolation from animals to humans and
10 for inter-individual variability. No uncertainty factor for database deficiencies was applied
due to the relatively complete database for the chemical, including a multigeneration
reproduction study and developmental toxicity studies in multiple species.
Confidence in the principal study is medium. Although the study was well-conducted
with a sufficient number of animals, the critical effect, a clear, dose-related increase in renal
histopathology, was observed in males only and a NOAEL was not identified. Females showed
an increase in kidney weight, but no renal lesions, and only at higher doses. However, it should
be pointed out that minimal to mild focal hypertrophy of convoluted renal tubules was also
occasionally noted in female mice. Confidence in the database is medium-to-high. Extensive
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clinical and histopathology data were available from well-conducted studies in mice, rats and
dogs, but several studies did not include dose levels high enough to observe effects. In addition
to systemic toxicity studies, the database includes developmental toxicity studies in rats, mice
and rabbits and a multigeneration reproduction study in rats. Overall confidence in the
provisional chronic RfD is medium.
FEASIBILITY OF DERIVING PROVISIONAL SUBCHRONIC AND CHRONIC
RfCs FOR BIFENOX
No human or animal data are available to derive a provisional subchronic or chronic RfC
for bifenox.
PROVISIONAL CARCINOGENICITY ASSESSMENT FOR BIFENOX
Weight-of-evidence Classification
Under the 2005 Guidelines for Carcinogen Risk Assessment (U.S. EPA, 2005), bifenox is
classified as having inadequate information to assess carcinogenic potential. Lifetime studies of
bifenox in the diet of Sprague-Dawley (Huntingdon Research, 1987a) and an unspecified strain
of albino (IBT, 1976a) rats found no significant increases in incidence of tumor development in
either strain. However, an MTD was not reached in either study. No carcinogenic effects were
observed in beagle dogs given capsule (Huntingdon Research, 1986) or dietary (IBT, 1976b)
administrations of bifenox for 1 and 2 years, respectively. The data from the dog studies are of
limited utility for carcinogenicity assessment, however, as group sizes were small (6/sex/dose,
with 2/sex/dose sacrificed at 6 months) and exposures were considerably less than lifetime (1-2
years). Small apparent increases in liver tumors (combined adenoma and carcinoma) in male
and female B6C3F1 mice treated with bifenox in the diet for two years (Litton Bionetics, 1982)
were within the historical control range and either not statistically significant (males) or only
marginally significant (p=0.041) by one (Gehan-Breslow trend test) of three tests (including
Cox's trend test and chi-square pair wise comparison) (females). The researchers did not
consider these findings to represent evidence of oncogenicity. Assays for genotoxicity of
bifenox were primarily negative, including in vitro and in vivo assays for mutagenicity,
clastogenicity, DNA effects, and cell transformation.
Quantitative Estimates of Carcinogenic Risk
Since the data for bifenox are inadequate to assess carcinogenic potential, no quantitative
estimates for carcinogenic risk from oral or inhalation exposures are derived.
REFERENCES
ACGIH (American Conference of Governmental Industrial Hygienists). 2005. 2005 Threshold
Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices.
ACGIH, Cincinnati, OH.
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ATSDR (Agency for Toxic Substances and Disease Registry). 2006. Toxicological Profile
Information Sheet. Online, http://www.atsdr.cdc.gov/toxpro2.html.
CDPR (California Environmental Protection Agency Department of Pesticide Regulation).
1988. Summary of Toxicology Data. Bifenox. Pesticide Registration Branch. Medical
Toxicology Branch. Online, http://www.cdpr.ca.gov/docs/toxsums/pdfs/1953.pdf
Eisenbeis, S.J., D.L. Lynch and A.E. Hampel. 1981. The Ames mutagen assay tested against
herbicides and herbicide combinations. Soil. Sci. 131:44-47.
Eli Lilly and Company. 1981a. Acute mouse oral study. Study No. M-O-267-81.
Eli Lilly and Company. 1981b. Acute mouse oral study. Study No. M-O-232-81.
Eli Lilly and Company. 1981c. Acute mouse oral study. Study No. M-O-255-81.
Francis, B.M. 1986. Teratogenicity of bifenox and nitrofen in rodents. J. Environ. Sci. Health.
B21: 303-317.
Francis, B.M., R.L. Metcalf, P.A. Lewis and N. Chernoff 1999. Maternal and developmental
toxicity of halogenated 4'-nitrodiphenyl ethers in mice. Teratology. 59: 69-80.
Hazleton Laboratories. 1986. Rabbit teratology study, bifenox technical, revised final report.
Project No. 656-125. EPA TRID 470143-008.
Health Canada. 2006a. First Priority Lit Assessments, http://www.hc-sc.gc.ca/ewh-
semt/pubs/contaminants/psll-lspl/index e.html
Health Canada. 2006b. Second Priority Lit Assessments, http://www.hc-sc.gc.ca/ewh-
semt/pub s/contaminants/p sl2-l sp2/index_e. html
Huntingdon Research Center, Ltd. 1984. Bifenox preliminary dose range finding study in rats
by dietary administration for 4 weeks. Project ID RNP 219/84584. EPA MRID 404831-02.
Huntingdon Research Center, Ltd. 1986. Bifenox oral toxicity in beagle dogs (repeated daily
dosage for 52 weeks) (final report). Project ID RNP 218/85998. EPA TRID 470156-036.
Huntingdon Research Center, Ltd. 1987a. Potential tumorigenic and toxic effects in prolonged
dietary administration to rats (final report). Project ID RNP 220/87642. EPA MRID 402707-01.
Huntingdon Research Center, Ltd. 1987b. Effect of bifenox on pregnancy of the rat. Project ID
RNP 242/861056. EPA MRID 405150-01.
IARC (International Agency for Research on Cancer). 2006. IARC Agents and Summary
Evaluations. Online, http://www-cie.iarc.fr/htdig/search.html
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10-19-2006
Industrial Biotest Laboratories (IBT). 1972. Teratogenic study with MC-4379 in albino rats.
IBTNo. B2156. 0013-008-01.
Industrial Biotest Laboratories (IBT). 1976a. Two-year chronic oral toxicity study with bifenox
in albino rats. IBT No. 621-05533. 0013-014-01.
Industrial Biotest Laboratories (IBT). 1976b. Two-year chronic oral toxicity study with bifenox
in beagle dogs. IBT No. 651-05532. 0013-013-02.
Industrial Biotest Laboratories (IBT). 1977. Three-generation reproduction study with bifenox
in albino rats. IBT No. 623-06793. 0013-006-01.
Kojima, H., E. Katsura, S. Takeuchi, et al. 2004. Screening for estrogen and androgen receptor
activities in 200 pesticides by in vitro reporter gene assays using Chinese hamster ovary cells.
Environ. Health Persp. 112: 524-531.
Kubo, T., K. Urano, and H. Utsumi. 2002. Mutagenicity characteristics of 255 environmental
chemicals. J. Health Sci. 48: 545-554.
Litton Bionetics. 1982. 24-Month carcinogenicity study in mice, bifenox (MCTR-1-79), final
report, volume 1. LBI Project No. 21063. EPA TRID 470089-052.
NIOSH (National Institute for Occupational Safety and Health). 2006. Online NIOSH Pocket
Guide to Chemical Hazards. Index by CASRN. Available at
http://www.cdc.gov/niosh/npg/npgd0267.html
NTP (National Toxicology Program). 2006. Management Status Report. Online.
http://ntp-server.niehs.nih.gov/cgi/iH Indexes/ALL SRCH/iH ALL SRCH Frames.html
Oguri, A., K. Karakama, N. Arakawa, et al. 1995. Detection of mutagenicity of diphenyl ether
herbicides in Salmonella typhimurium YG1026 and YG1021. Mutat. Res. 346: 57-60.
OSHA (Occupational Safety and Health Administration). 2006. OSHA Standard 1910.1000
Table Z-l. Part Z, Toxic and Hazardous Substances. Online.
http://www.osha-slc.gov/OshStd data/1910 1000 TABLE Z-l.html
Plewa, M.J., E.D. Wagner, G.J. Gentile and J.M. Gentile. 1984. An evaluation of the genotoxic
properties of herbicides following plant and animal activation. Mutat. Res. 136: 233-246.
Sivikova, K. and J. Dianovsky. 1999. Genetic activity of the commercial herbicide containing
bifenox in bovine peripheral lymphocytes. Mutat. Res. 439:129-135.
Tanaka, Y., N. Shimizu, H. Tsukatani, et al. 2002. The mutagenicity of amino-derivatives of
diphenyl ether herbicides in new Salmonella typhimurium tester strains. Water Sci. Technol. 46:
395-400.
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U.S.D.A. (U.S. Department of Agriculture). 1987. Pesticide Background Statements, Vol. III.
Nursery Pesticides. Forest Service, Washington, DC. Agriculture Handbook No. 670. NTIS
PB89-226716.
U.S. EPA. 1988. Recommendations for and Documentation of Biological Values for Use in
Risk Assessment. Environmental Criteria and Assessment Office, Office of Health and
Environmental Assessment, Office of Research and Development, U.S. Environmental
Protection Agency, Cincinnati, OH. PB88-17874. EPA/600/6-87/008.
U.S. EPA. 1991. Chemical Assessments and Related Activities (CARA). Office of Health and
Environmental Assessment, Washington, DC. April.
U.S. EPA. 1994a. Chemicals registered for the first time as pesticidal active ingredients under
FIFRA. Economic Analysis Branch, Biological and Economic Analysis Division, Office of
Pesticide Programs, Washington, DC. December 1994. Online.
http://www.epa.gov/oppbeadl/newais/newais.pdf
U.S. EPA. 1994b. Chemical Assessments and Related Activities (CARA). Office of Health and
Environmental Assessment, Washington, DC. December.
U.S. EPA. 1994b. Chemical Assessments and Related Activities (CARA). Office of Health and
Environmental Assessment, Washington, DC. December.
U.S. EPA. 1997a. Health Effects Assessment Summary Tables. Annual Update. FY-1997.
Office of Research and Development, Office of Emergency and Remedial Response,
Washington, DC. July 1997. EPA/540/R-97/036. NTIS PB97-921199.
U.S. EPA. 1997b. Bifenox. Office of Pesticide Programs Reference Dose Tracking Report.
Online, http://npic.orst.edu/tracking.htm
U.S. EPA. 1998. Status of pesticides in registration, reregi strati on, and special review (Rainbow
Report). Special Review and Reregi strati on Division, Office of Pesticide Programs,
Washington, DC. Spring 1998. Online. http://www.epa.gov/oppsrrdl/Rainbow/98rainbo.pdf
U.S. EPA. 2000. Benchmark Dose Technical Guidance Document. External Peer Review
Draft. Risk Assessment Forum, Washington, DC. EPA/63O/R-OO/OOl. October.
U.S. EPA. 2004. 2004 Edition of the Drinking Water Standards and Health Advisories. Office
of Water, Washington, DC. EPA 822-R-02-038. Washington, DC.
http://www.epa.gov/waterscience/drinking/standards/dwstandards.pdf
U.S. EPA. 2005. Guidelines for Carcinogen Risk Assessment. Risk Assessment Forum,
Washington, DC. EPA/630/P-03/001B. www.epa.gov/cancerguidelines.
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U.S. EPA. 2006. Integrated Risk Information System (IRIS). Online. Office of Research and
Development, National Center for Environmental Assessment, Washington, DC.
http://www.epa.gov/iris/
WHO (World Health Organization). 2006. Online Catalogs for the Environmental Criteria
Series. Available at http://www.inchem.org/pages/ehc.html
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APPENDIX A
Dose-response modeling using the BMDS (Version 1.3.2) and a BMR of 10% extra risk
was performed on the incidence data of Litton Bionetics (1982) for cytomegalic renal
hypertrophy of convoluted renal tubules of male B6C3F1 mice. Modeling produced estimates
(BMDio) and lower bounds on the 95% confidence interval (BMDLio) of exposure levels likely
to result in 10% extra risk of developing cytomegalic renal hypertrophy in mice. All available
dichotomous models were fit to the data and the best fit was determined using guidelines
described in U.S. EPA (2000). Goodness-of-fit was evaluated using the Chi-square statistic
calculated by the BMDS. Adequate model fit to the data was indicated by a p-value > 0.1;
models with a p-value <0.1 were not considered. Subsequently, BMDLio estimates were ranked
using the Akaike Information Criterion (AIC) reported by the BMDS program. The model with
the lowest AIC was considered to provide a superior fit. Modeling results are summarized in
Table A-l. No adequately-fit models resulted from use of all four dose levels; dropping the high
dose resulted in adequate fit of a single model, the log-logistic model (Figure A-l). Fit of the
log-logistic model resulted in BMDio and BMDLio estimates of 1.34 mg/kg-day and 0.91 mg/kg-
day, respectively.
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Table A-l. Benchmark dose modeling results for cytomegalic
changes (focal hypertrophy) of convoluted renal tubules in male
B6C3F1 mice (Litton Bionetics, 1982) - high dose dropped
Model
AIC
p-Value
BMDio
BMDLio
Quantal Linear
182.974
0.0984
2.3162
1.7827
Weibulf
182.974
0.0984
2.3162
1.7827
Multistage13
182.974
0.0984
2.3162
1.7827
Gamma"
182.974
0.0984
2.3162
1.7827
Log Probitc
185.351
0.0210
3.8078
2.9072
Log Logistic0
180.398
0.7671
1.3366
0.9113
Logistic
189.814
0.0026
5.2781
4.2860
Probit
189.479
0.0030
5.1003
4.2267
Quantal Quadratic
194.996
0.0002
9.0841
7.6675
Abbreviations: AIC = Akaike Information Criterion; BMDio = Benchmark Dose,
maximum likelihood estimate of the dose producing a 10% extra risk in convolutes
renal tubules; BMDLio = 95% lower confidence limit on the BMDio.
aPower restricted to >=1
bBetas restricted to >=0, Degree of polynomial = 1
cSlope restricted to >=1
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Log-Logistic Model with 0.95 Confidence Level
dose
14:19 05/05 2006
Figure A-l. Fit of the Log-Logistic dose-response model to the incidence of focal
hypertrophy of convoluted tubules in male B6C3F1 mice given dietary bifenox for 2 years
(Litton Bionetics, 1982)
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Logistic Model $Revision: 2.1 $ $Date: 2000/02/26 03:38:20 $
Input Data File: C:\BMD\BIFENOX\LITTON.(d)
Gnuplot Plotting File: C:\BMD\BIFENOX\LITTON.plt
Fri May 05 14:19:25 2006
BMDS MODEL RUN
The form of the probability function is:
P[response] = background+(1-background)/[1+EXP(-intercept-slope*Log(dose))]
Dependent variable = incidence
Independent variable = dose_ppm
Slope parameter is restricted as slope >= 1
Total number of observations = 3
Total number of records with missing values = 0
Maximum number of iterations = 25 0
Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008
User has chosen the log transformed model
Default Initial Parameter Values
background = 0.0892857
intercept =	-2.48897
slope =	1
Asymptotic Correlation Matrix of Parameter Estimates
( *** The model parameter(s) -slope
have been estimated at a boundary point, or have been specified by
the user,
and do not appear in the correlation matrix )
background intercept
background	1	-0.37
intercept	-0.37	1
Parameter Estimates
Variable
background
intercept
slope
Estimate
0.0906975
-2.48738
1
Std. Err.
0. 0384068
0.239702
NA
NA - Indicates that this parameter has hit a bound
implied by some ineguality constraint and thus
has no standard error.
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Model
Full model
Fitted model
Reduced model
AIC:
Analysis of Deviance Table
Deviance Test DF
Log(likelihood)
-88.1553
-88.1989
-114.104
180.398
0.0871849
51.8984
P-value
0.7678
<.0001
Goodness of Fit
Dose
Est. Prob.
Expected
Observed
Size
Scaled
Residual
0.0000
7.0000
30.0000
Chi-square =
0.0907
0. 4252
0.7397
0. 09
5.079
24.235
40.686
DF = 1
5
25
40
P-value
56
57
55
0.7671
-0.03679
0.2049
-0.2107
Benchmark Dose Computation
Specified effect =
Risk Type	=
Confidence level =
BMD =
BMDL =
0.1
Extra risk
0.95
1.33664
0.911304
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