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

350 CHAPIN ET AL.
and determining the precise weight. Epididymal sperm
counts were obtained. Histopathological examinations
were conducted for organs fixed in Bouin solution. Data
were analyzed by Bartlett test to determine homogeneity
of variance, followed by ANOVA when homogeneity of
variance was confirmed or Kruskal–Wallis analysis of
ranks when variance was not homogenous. Dunnett test
was used for multiple comparisons.
In the bisphenol A group, there were no significant
differences in body weight gain or terminal body
weights. [Data were not shown.] There were no
significant differences in absolute or relative (to body
weight) weights of the testis, epididymis, or seminal
vesicles. There were no significant effects on sperm
count. No histopathological alterations in reproductive
organs were reported. The study authors concluded that
low-dose bisphenol A exposure of mice did not reduce
sperm density.
Strengths/Weaknesses: This study was well conducted
and adds to the understanding of the potential
effects of low doses of bisphenol A administered by a
relevant route of exposure. Strengths are an appropriate
number of mice per group, the use of response to 17bestradiol
in 2 strains of mice to identify the most sensitive
strain, and the presentation of sperm data in light of
historical control data.
Utility (Adequacy) for CERHR Evaluation Process:
This study is adequate and of high utility for the
evaluation process.
Peknicová et al. (2002), supported by the Czech
Republic and EU, examined the effects of bisphenol A
exposure on mouse sperm. CD-1 mice were given ST1
feed (Velaz a.s., Prague). Three generations of mice were
exposed to bisphenol A [purity not indicated] through
drinking water at doses of 0.000002 and 0.000020 mg ‘‘/
animal’s weight/day. ’’ It was stated that there were 6
pairs of mice in the control group. Litter size was
evaluated in 3 generations; 1 litter was examined in the
first and second generation and 2 litters were examined
in the third generation. In each generation, samples of
sperm were collected from all males and a histopathological
investigation of testes was conducted in Z3
males/group. Sperm acrosomal status was assessed
using an immunohistochemical and Western blot method.
Statistical analyses included ANOVA and Newman–
Keuls test. [Very few experimental details were provided.
No information was provided on bedding and
caging materials, bisphenol A purity, the numbers of
mice in each treatment group, treatment of the control
group, ages of mice during treatment, durations of
treatment, sample sizes and litter representation for
sperm effects, and mating procedures. It was not clear
if female rats were also treated.] Litter sizes were
significantly reduced in the first and second generation
of mice treated with the low dose (5–6.7 pups/litter vs.
11.5–12 pups/litter in controls). There were no effects of
bisphenol A treatment on testes weight. [Data were not
shown by authors.] Pathological changes observed in
testes from the low-dose group included damaged
seminiferous tubule and reduced spermatogenesis. Acrosome
integrity, evaluated as percent cells binding
monoclonal antibodies to acrosin and intra-acrosomal
proteins, was significantly reduced in all 3 generations of
the low-dose group (48.5–57.7 compared to 93.3–95%
integrity in controls) and the third generation of the high-
dose group (62.5 compared to 93.3% integrity in
controls). [While the text of the study stated that
acrosomal integrity was significantly affected only in
the third generation of the high-dose group, the caption
for Figure 7 of the study stated that both the second and
third generations were significantly affected. Based on
findings reported in the figure, it appears that the
description in the text is correct.] The study authors
concluded that bisphenol A exposure negatively impacts
fertility, spermatogenesis, and sperm quality in mice.
Strengths/Weaknesses: Although potentially interesting
findings are presented, the study lacks many
important details and sample sizes are critically
inadequate.
Utility (Adequacy) for CERHR Evaluation Process:
Due to study design concerns, this study is inadequate
and has no utility for the evaluation.
Takahashi and Oishi (2003), support not indicated,
examined species, strain, and route differences in
reproductive systems of male rodents exposed to bisphenol
A. Studies on mice are discussed here, and
studies on rats are discussed in Section 4.2.2.1. Animals
were housed in stainless steel suspended cages or ‘‘chipbedded’’
plastic cages. [No information was provided
about the type of chow used.] Animals used in this
study were 4 weeks old at the start of dosing. In the
dietary portion of the study, CD-1 (ICR) mice and
C57BL/6CrSlc mice were given feed containing 0 or
0.25% bisphenol A (499.0% purity) for 2 months. There
were 8 animals in each dose group. The 0.25% dose was
reported to produce minimal testicular effects in a
previous study. Mean bisphenol A intakes were estimated
by study authors at B400 mg/kg bw/day in mice.
The parenteral exposure studies were performed only in
rats. Animals were observed daily for clinical signs, and
body weight and food intake were measured. Animals
were killed at the end of the dosing period. Liver, kidney,
and reproductive organs were weighed. Testes were
fixed in formaldehyde solution and examined histologically.
The study authors noted that the appropriate
fixative for the testis is Bouin solution, but that obvious
and severe injuries could be detected with the method
used in the present study. Testosterone was measured in
serum by ELISA. Daily sperm production and efficiency
and epididymal sperm reserves were evaluated. Statistical
analyses included F test, Student t-test, Aspin–
Welch test, Bartlett test, ANOVA, Dunnett test, Kruskall–
Wallis test, Dunnett non-parametric test, Wilcoxon ranksum
test, w 2 test, Mantel–Haenzel test, and Fisher exact
test.
There were no significant effects on organ or body
weights in C57BL/6CrSlc mice exposed through
diet. In CD-1 (ICR) mice exposed through diet, there
were increases in absolute testis [16%], liver [12%],
and kidney [20%] weights and a decrease in absolute
epididymis [12%] weight. The study authors
reported that relative testis weight was not significantly
affected, but when the value from 1 mouse with a high
relative testis weight was deleted, the effect attained
statistical significance. [Data were not shown by study
authors.] No effects were reported for testis histopathology,
daily sperm production or efficiency of production,
epididymal sperm reserves, or serum testosterone levels
in mice exposed to bisphenol A through diet. [Data were
not shown by study authors.] The study authors
Birth Defects Research (Part B) 83:157–395, 2008