Monograph on the Potential Human Reproductive and ... - OEHHA

254 CHAPIN ET AL.
120 mg/kg bw/day bisphenol A groups were injected
with corn oil during the same time period. Surviving
male offspring were killed and necropsied at 65 weeks of
age. Blood was collected for analysis of serum testosterone
levels in 5 rats/group. Reproductive organs were
examined for gross abnormalities, weighed, and fixed in
10% buffered formalin. A histopathological examination
of the prostate was conducted. Body and organ weight
data were analyzed by Student t-test. The incidence of
histopathological lesions was evaluated by Fisher exact
probability test. [It appears that the litter was considered
the statistical unit in analyses for numbers and
survival of pups at birth. Offspring were apparently
considered the statistical unit for other analyses.]
Body weights of dams in the 120 mg/kg bw/day
group were significantly lower than control values from
GD 14–20. There were no consistent or dose-related
effects on dam body weights during lactation, although a
significant increase in body weight was observed in
dams of the 0.05 mg/kg bw/day group on PND 14.
Exposure to bisphenol A had no effect on gestation
period duration or number of implantation sites. In pups
exposed to bisphenol A, there were no differences in
number of live births, sex ratio, external anomalies, or
body weights during the lactation period. [Data for pup
body weights were not shown by study authors.]
Terminal body weight of pups exposed to 0.05 mg/kg
bw/day bisphenol A before treatment with 3,2-dimethyl­
4-aminobiphenyl were significantly higher than controls
[by 12%]. Exposure to bisphenol A had no effect on
weights of prostate, testis, or epididymis. Incidences of
prostatic intraepithelial neoplasia, carcinoma, and atypical
hyperplasia were not increased by bisphenol A
treatment, and there were no increases in tumors found
in non-reproductive organs. No effect was observed on
serum testosterone levels. The study authors concluded
that exposure of rat dams to bisphenol A during the
gestation and lactation periods does not predispose their
offspring to prostate cancer development.
Strengths/Weaknesses: Strengths are the range of low
dose levels, the use of an additional strain (Fischer 344
rat), and the endpoints evaluated. The design is reasonable
for some of the endpoints measured, but sample
sizes are inadequate for the prostate cancer endpoint and
hormonal endpoints in particular. Statistical accounting
for litter effects is unclear for neonatal measures, body
weight, and fertility endpoints.
Utility (Adequacy) for CERHR Evaluation Process:
This study is inadequate based on insufficient sample
size given the endpoints (i.e., tumors response) and lack
of consistently accounting for litter effects.
Yoshida et al. (2004), supported by the Japanese
Ministry of Health, Labor, and Welfare, examined the
effects of bisphenol A exposure on development of the
rat female reproductive tract. Donryu rats (12–19/group)
were gavaged with bisphenol A [purity not reported] at
0 (carboxymethylcellulose solution), 0.006, or 6 mg/kg
bw/day from GD 2 to the day before weaning of pups at
21 days post delivery. The low dose was said to represent
average daily intake from canned foods and the highdose
was reported to represent the maximum dose level
detected in plastic plates for children. [It is assumed the
authors meant estimated exposure levels for children
eating off plastic plates.] Bisphenol A levels were
measured in maternal and pup tissues, and those values
are reported in Section 2.1.2.2.1. After delivery, dams and
litters were housed in plastic cages with wood chip
bedding. Tap water was stored in plastic containers. The
only information provided about feed was that it was a
commercial pellet diet. Samples of tap water, drinking
water from plastic containers, and feed were measured
for bisphenol A content by HPLC. Offspring were sexed,
weighed, and examined for external abnormalities on
PND 1 and then weighed weekly through PND 21.
Litters were adjusted to 8–10 pups at PND 4 or 6 (day of
birth 5 PND 0). Dams were weighed, and observed
during the study and killed following weaning of litters
on PND 21. Implantation sites were examined and
organs including uterus, vagina, and ovaries were fixed
in 10% neutral buffered formalin and examined histologically.
[It does not appear that results of histopathological
testing in dams were reported.] All female
offspring were examined for vaginal opening, and
following vaginal opening, vaginal smears were taken
for the remainder of the study. Three to 5 offspring/
group from different litters were killed on PND 10, 14,
21, or 28 and at 8 weeks of age. At most time
periods, uteri were weighed, preserved in 10% neutral
buffered formalin, and examined histopathologically to
determine development of uterine glands. Ovaries and
vagina were also examined histologically. ERa was
determined using an immunohistochemical method.
Serum was collected for measurement of FSH and LH
by RIA. Four offspring/group from different litters were
killed at 8 weeks of age on the morning of estrus to
examine ovulation by counting ova in oviducts. Initiation
of carcinogenesis following injection of the uterine
horn with N-ethyl-N 0 -nitro-nitrosoguanidine was examined
at 11 weeks of age in 35 or 36 animals/group.
At B24 weeks following cancer initiation, the 24–30
surviving animals/group were killed and uteri were
examined histologically to determine the presence of
tumors and other lesions. Statistical analyses included
ANOVA and Dunnett test. [Most of the data for
endpoints evaluated at birth appeared to be presented
and apparently analyzed on a litter basis. For other
data, it appears that offspring were considered the
statistical unit.]
Bisphenol A was not detected in fresh tap water but
was detected at B3 ng/mL following storage in plastic
containers. The bisphenol A concentration in feed was
B40 ng/g. In dams exposed to bisphenol A, there
were no clinical signs of toxicity or effects on body
weight, implantation sites, or gestation length. Bisphenol
A exposure had no effect on litter size, pup body
weight at birth and through PND 21, external abnormalities
in pups or age of vaginal opening. In uteri of
bisphenol A-exposed offspring, there were no effects on
weight, gland development, ERa, or cell proliferation.
No increase in lesions was reported in organs of the
alimentary, urinary, respiratory, or nervous system.
[Data were not shown by study authors.] Bisphenol A
exposure had no effect on ovulation, estrous cyclicity,
or serum FSH or LH levels. There were no effects on
uterine preneoplastic or neoplastic lesions or ovarian
histopathology following bisphenol A treatment.
The study authors concluded that perinatal exposure
to bisphenol A at levels comparable to human
exposure did not affect the reproductive system of
female rats.
Birth Defects Research (Part B) 83:157–395, 2008