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

that 44.4% of prostates contained increased a focal
luminal polymorphonuclear cellular infiltrate that was
milder in severity compared to prostates from the 17bestradiol
group. The study authors noted the discrepancy
between the results obtained by myeloperoxidase assay
and histological observation in the bisphenol A group
and stated that the discrepancy may have been due to
evaluation of the whole tissue by myeloperoxidase assay
versus only one section of the tissue by histological
evaluation. Bisphenol A had no effect on prostate DNA
content. In addition to prostate inflammation, effects
observed in the 17b-estradiol group were increased
serum prolactin levels on PND 29 and elevated myeloperoxidase
and DNA content in lateral prostate on PND
120. Based on these findings, the study authors concluded
that chemically induced, transient increases in
prolactin secretion in the prepubertal period can lead to
increased incidence of lateral prostate inflammation in
120-day-old rats.
Strengths/Weaknesses: Comparison with other agents
is a strength. Weaknesses include low to moderate
sample sizes and the use of a single high-dose level of
bisphenol A through subcutaneous administration.
Utility (Adequacy) for CERHR Evaluation Process:
This study is adequate for the evaluation process but has
limited utility due to concerns about sample sizes and
route of administration of treatment.
Atanassova et al. (2000), supported by the European
Center for the Ecotoxicology of Chemicals and AstraZeneca,
examined the effects of neonatal bisphenol A
exposure on the reproductive system of male rats. Wistar
rats were fed rat and mouse breeding diet No. 3, which
contains 15.5% soy meal flour. [No information was
provided about caging and bedding materials.] Litters
of 8–12 male rats from randomized litter origin were
assembled by cross-fostering pups on PND 1 (day of
birth). On PND 2–12, rats were s.c. injected with corn oil
vehicle or bisphenol A [purity not given] 0.5 mg/day.
[Assuming a 5–25 g body weight during this interval,
this dose would be B100 mg/kg bw/day at the beginning
of the interval and B20 mg/kg bw/day at the end
of the interval.] Other groups of rats were s.c. injected
with 0.01–10 mg diethylstilbestrol every other day between
PND 2–12 or 2 mg 4-tert-octylphenol/day during
PND 2–12. Rats were killed on PND 18, 25, and 90–100.
At PND 18 and 25, testes were weighed and fixed in
Bouin solution. Testicular cell numbers and seminiferous
tubule lumen formation were determined by standard
point counting of cell nuclei. Apoptosis was assessed by
DNA fragmentation detected by in situ DNA 3 0 -end
labeling. Spermatocyte nuclear volume as a fraction of
Sertoli cell nuclear volume was calculated as ‘‘an index of
spermatogenic efficiency.’’ Plasma FSH and inhibin B
were measured by RIA and ELISA methods, respectively.
Fertility was assessed at 80–90 days of age; rats were
mated for 7 days and number of pups was counted at
birth. The number of rats/group examined was 7–14 at
18 days of age, 4–12 at 25 days of age, and 6 in fertility
testing. Data were analyzed by ANOVA.
Significant effects observed on PND 18 were advanced
testicular lumen formation and increases in testis weight,
Sertoli cell volume/testis, and spermatocyte nuclear
volume/unit Sertoli cell. A decrease in germ cell
apoptosis was also described on PND 18 but was not
statistically significant. Plasma FSH levels were
Birth Defects Research (Part B) 83:157–395, 2008
BISPHENOL A
269
increased significantly on PND 18, but there was no
effect on plasma inhibin B concentration. The only
significant effect observed on PND 25 was increased
plasma FSH levels. Testis weight was increased in
adulthood, but there were no effects on fertility or litter
size. Effects observed with octylphenol were similar to
those observed with bisphenol A. In contrast, exposure to
one or more doses of diethylstilbestrol resulted in
increased apoptosis, decreased plasma inhibin levels,
decreased Sertoli cell nuclear volume, and changes in
spermatocyte/Sertoli cell ratios. The study authors
concluded that the effect of bisphenol A on spermatogenic
processes is benign.
Strengths/Weaknesses: Comparison with other agents
is a strength. Weaknesses include low to moderate
sample sizes, the use of a single high-dose level of
bisphenol A through subcutaneous administration, 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 the evaluation process but has
limited utility due to concerns about sample sizes and
route of administration of treatment.
Williams et al. (2001), supported by the European
Centre for Ecotoxicology, examined the effect of neonatal
bisphenol A exposure on seminal vesicle structure and
expression of sex steroid receptors in rats. On PND 2
(day of birth 5 PND 1), litters consisting of 8–14 male
Wistar rat pups were derived through cross-fostering.
Rats were s.c. injected with corn oil vehicle or 0.5 mg/
day bisphenol A on PND 2–12. [Assuming a 5–25 g body
weight during this interval, the dose would be
B100 mg/kg/day at the beginning of the interval and
B20 mg/kg bw/day at the end of the interval.] The dose
was based on the highest amount that could remain in
solution. A positive control group was injected with
diethylstilbestrol at 0.1, 1, or 10 mg/day on PND 2, 4, 6, 8,
10, and 12. Ethinyl estradiol was administered at 10 mg/
day, according to the protocol for diethylstilbestrol.
Control animals for each compound were dosed with
vehicle on the appropriate days, and because no
differences were noted for controls, data were pooled.
The effects of 4-tert-octylphenol, genistein, Antarelix,
flutamide, and tamoxifen were also examined but will
not be discussed. [No information was provided about
feed, caging or bedding materials, or purity of
compounds.] Animals were killed on PND 18, and
seminal vesicles from 11–15 animals/group were collected
and stored in Bouin solution. Seminal vesicles
were examined for gross abnormalities in stroma and
epithelium. Immunolocalization studies were conducted
to assess ERb, ERa androgen receptor, and progesterone
receptor proteins in the seminal vesicle. Studies were
replicated 3–5 times using samples from at least 6
animals/group. Results were scored subjectively.
The gross structure of the seminal vesicles from
bisphenol A-treated rats appeared normal, and there
were no changes in ERb, ERa, androgen receptor, or
progesterone receptor proteins in the seminal vesicle. In
contrast, diethylstilbestrol induced changes in seminal
vesicle morphology, increased ERa and progesterone
receptor, and decreased androgen receptor. Effects of
ethinyl estradiol were similar to those observed with
diethylstilbestrol. The study authors concluded that the
lack of bisphenol A effects suggested that only high-