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

268 CHAPIN ET AL.
duration of adverse effects induced by estrogenic
compounds were broadly similar to the estrogenic
potencies of the compounds.
Strengths/Weaknesses: This is a carefully performed
study, although the inclusion of many methodological
details (vide supra) would have improved it. Strengths
include the use of a wide range of estrogenic compounds
to alter testicular development. A limitation for the
present purpose is that only a single dose level of
bisphenol A was administered subcutaneously. A weakness
is that tissues other than the testis were not
examined. Other weaknesses include sample sizes ranging
from 3–20 examined pups across groups and s.c.
administration.
Utility (Adequacy) for CERHR Evaluation Process:
This study is inadequate for evaluation due to lack of
clarity about experimental or statistical control for litter
effects.
Nagao et al. (1999), supported by the Japanese
Ministry of Health and Welfare, examined the effects of
neonatal bisphenol A exposure on reproductive function
of male and female Sprague–Dawley given CE-2 feed
(Clea Japan). [No information was provided about
caging or bedding materials.] From PND 1–5 (birth by
16:00 considered PND 0), 28–31 pups/sex/group were
s.c. injected with corn oil vehicle, 300 mg/kg bw/day
bisphenol A [purity not reported], or 2 mg/kg bw/day
estradiol benzoate. Pups within litters were treated with
the same dose. Doses were based on results of preliminary
studies that demonstrated no effect on growth
or viability at bisphenol A doses up to 300 mg/kg bw/
day administered by s.c. injection in the neonatal period.
Pups were examined for viability from PND 6–21. On
PND 21, 5 pups/sex/group were randomly selected and
killed. Pups were transcardially perfused, and reproductive
organs were collected for histopathological evaluation.
At 12 weeks of age, 22–25 rats/sex were mated with
untreated rats. Females were killed on GD 13 for an
evaluation of implant number and viability of embryos.
After fertility evaluation, sexual behavior with a sexually
receptive female was assessed in 10 males/group.
Following evaluation of sexual behavior, 15 male rats/
group were killed for measurement of reproductive
organ and brain weight. Histopathology of reproductive
organs and SDN-POA volume were measured in 5
males/group. Copulation and fertility indices were
analyzed by w 2 and Fisher exact one-tailed test. Data
for other endpoints were analyzed by Student t-test.
In rats treated with bisphenol A, there were no clinical
signs of toxicity or effects on pup viability or body
weight gain during or following the lactation period
[data for pup viability not shown by study authors].
There were no effects on age of vaginal opening or
preputial separation. Copulation and fertility indices and
numbers of live embryos/litter were not affected in male
or female rats treated with bisphenol A. Bisphenol A
treatment did not affect sexual behaviors of males, as
determined by number of mounts, intromissions, and
ejaculations. No histopathological alterations were observed
in the ovaries of treated females at 21 days of age
or in the epididymis, prostate, or seminal vesicles of
treated male rats at 21 days or 14 weeks of age. [The
prostatic lobe not specified; based on the figure
provided, the lobe appears to have been ventral
prostate. The Expert Panel notes that the number of
apically located nuclei may be elevated by 14 weeks of
age over what would normally be expected; however,
this observation cannot be determined definitively
based on a single high power field and in the absence
of a matched control.] No effect of treatment was
observed on the SDN-POA of males. In contrast to the
bisphenol A groups, rats treated with estradiol benzoate
experienced decreased body weight gain, compromised
male sexual behavior, infertility, lesions in reproductive
organs, and reduced volume of the SDN-POA. The study
authors concluded that neonatal exposure to a relatively
high-dose of bisphenol A had no effect on morphological
development or function of the reproductive system.
Strengths/Weaknesses: Strengths include a well performed
and documented study that compared effects of
bisphenol A and estradiol benzoate. Additional strengths
include documentation of both behavioral (mating
behavior) and biological (genital tract development)
endpoints in both male and female rats. Weaknesses
include the use of only a single dose level of bisphenol A
via s.c. injection, and no accounting for litter effects
within the context of individual animal treatments
within litters.
Utility (Adequacy) for CERHR Evaluation Process:
This study is adequate for evaluation, however, utility is
limited by subcutaneous administration.
Stoker et al. (1999), support not indicated, examined
the effects of prepubertal bisphenol A exposure on
prolactin secretion and prostate size in rats. [No
information was provided about feed, bedding, or
caging materials.] On PND 22–32 (day of birth 5 PND
0), 15–17 male Wistar rats from different litters/group
were s.c. injected with bisphenol A [purity not reported]
at 0 (sesame oil vehicle) or 50 mg/kg bw [assumed to be
50 mg/kg bw/day]. Another group of rats was administered
17b-estradiol through a s.c. Silastic tube implant
[dose administered not clear]. On PND 29, 6 animals/
dose were killed and blood was collected for measurement
of serum prolactin concentration. The remaining
rats (n 5 9–11/group) were killed at 120 days of age.
Prolactin levels were measured in serum and anterior
pituitary by RIA. Inflammation was visually examined in
the ventral and lateral prostate. Left lateral and ventral
prostates were weighed and lateral prostate was analyzed
for myeloperoxidase (an indicator of neutrophil
numbers) and DNA. The right lateral prostate was
subjected to histological examination. Statistical analyses
included ANOVA, Dunnett t-test for multiple comparison,
and Fisher exact probability test.
On PND 29, serum prolactin levels were significantly
increased by B210% in rats of the bisphenol A group
compared to the control group. On PND 120, there was
no effect on prolactin levels in serum or pituitary in the
bisphenol A group. Ventral prostate weight was unaffected
but lateral prostate weight was increased [by
B25%] in the bisphenol A group. Exposure to bisphenol
A had no effect on body or testis weight. [Data were not
shown by study authors.] The myeloperoxidase assay
was reported to show a ‘‘trend’’ for lateral prostate
inflammation in the bisphenol A group. [Trend was not
defined; there was no statistical difference between the
bisphenol A group and the control in the myeloperoxidase
assay.] No histological evidence of inflammation
was observed in prostates from the control group. In the
bisphenol A group, histopathological analyses revealed
Birth Defects Research (Part B) 83:157–395, 2008