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

262 CHAPIN ET AL.
purposeful confounding of litter of origin during the crossfostering
process. In addition, the sample size of 7 dams in
the 0.040 mg/kg bw/day bisphenol A group and the
examination of n 5 11 male and n 5 9 female offspring in
the prenatal exposure group raise questions about experimental
or statistical accounting for litter effects.
Utility (Adequacy) for CERHR Evaluation Process:
The data presented are inadequate due to the methodological
design and lack of clarity on accounting for litter
effects.
Negishi et al. (2003), support not indicated, examined
the effect of perinatal bisphenol A exposure on behavior
of rats. F344/N rats (n 5 8–9/group) were orally exposed
to bisphenol A at 0 (olive oil vehicle), 4, 40, or 400 mg/kg
bw/day from GD 10–PND 20. GD 0 was defined as the
day that vaginal sperm were detected and PND 0 was
defined as the day of parturition. [No information was
provided on purity of bisphenol A, the specific method
of oral dosing, type of chow used, or composition of
bedding or caging materials.] Dams were observed and
weighed throughout the study. On PND 0, pups were
counted, weighed, and culled to 8/litter with equal
numbers/sex when possible. Pups were weighed periodically
from PND 7–84. Pups were housed as same-sex
littermates following weaning on PND 21. On weaning
of pups, dams were killed and body and organ
weights were recorded. Behavioral testing of offspring
consisted of spontaneous motor activity measured at 28–
34 days of age (n 5 12–27/group), active avoidance
testing conducted at 28–34 and 56–62 days of age
(n 5 8–9/group), and open-field behavior evaluations at
56–62 days of age (n 5 9–18/group). Litter was not
accounted for in the analyses. On PND 62, offspring
were randomly selected (8/sex/group) and killed for
evaluation of body and organ weights. Statistical
analyses included ANOVA, nested ANCOVA, and posthoc
Fisher protected least significant difference test.
[Data analyzed at birth were presented and analyzed on
a per litter basis. Postnatal data were apparently
analyzed on a pup basis.]
Maternal body weight gain was reduced during the
gestation and lactation period in dams exposed to the
mid- or high-dose. The only organ weight effects in dams
were reduced absolute and relative (to body weight)
thymus weight. There were no effects on weights of liver,
kidney, or spleen in dams. Bisphenol A treatment did not
affect the number of pups/litter or sex ratio. In male
offspring, body weights were lower than control values
on PND 7 and 28 at the mid-dose, and PND 7, 21, 28, and
56 at the high-dose. Body weights of female offspring
were lower than controls at PND 7 and 28 at the low- and
mid-dose and PND 7, 21, and 28 at the high-dose. On
PND 62, there were no effects on body weight or liver,
kidney, spleen, thymus, brain, or testis weights. There
were no effects on spontaneous activity, but total
immobile time was increased in females of the mid-dose
group. Performance of males in avoidance testing
improved in the mid- and high-dose group at 4 weeks
of age but decreased in the low-dose group at 8 weeks of
age. Increased grooming by males of the low-dose group
was observed in open-field testing. The study authors
concluded that perinatal bisphenol A exposure caused
behavioral alterations that differed by sex.
Strengths/Weaknesses: Doses were sufficiently high
to produce gross body weight changes, and 3 different
measures of behavior were collected, as well as organ
weights at necropsy from the same animals. Weaknesses
include a lack of statistical accounting for possible litter
effects in the postnatal analysis, the lack of an evaluation
of hormone-dependent behaviors, and the lack of
assessment of more hormone-dependent tissues (prostate,
levator ani muscle, etc.) or processes (age at
balanopreputial separation, postnatal anogenital
distance).
Utility (Adequacy) for CERHR Evaluation Process:
This study is inadequate for the evaluation process due
to a failure to account for litter effects.
Negishi et al. (2004a), support not indicated, examined
the effect of perinatal bisphenol A [purity not indicated]
exposure on the behavior of rats. The effects of nonylphenol
were also examined but will not be discussed.
F344/N rats (10 or 11/group) were gavaged with bisphenol
A at 0 (corn oil vehicle) or 0.1 mg/kg bw/day
from GD 3–PND 20. GD 0 was defined as the day that
vaginal sperm was detected, and PND 0 was the day of
parturition. At birth, pups were counted and weighed.
Litters were culled to 6 pups, with equal numbers of each
sex when possible. Pups were weighed throughout the
postnatal period. At weaning, dams were killed and organ
weights were measured. One male pup/litter (n 5 8–10/
group) was subjected to a series of behavioral tests. The
remaining male pups were killed for measurement of
organ weights at 21 days or 8 weeks of age. Neurobehavioral
endpoints evaluated included open-field behavior
at 8 weeks of age, spontaneous motor activity at 12 weeks
of age, passive avoidance at 13 weeks of age, performance
in the elevated-plus maze at 14 weeks of age, and active
avoidance at 15 weeks of age. At 22–24 weeks of age, a
monoamine reduction test was performed: rats were
injected with the monoamine oxidase inhibitor trans-2phenylcyclopropylamine
hydrochloride or with saline,
and behavior was then evaluated. Data were analyzed by
ANOVA, and if statistical significance was obtained,
Fisher protected least significant difference test was
conducted. Behavioral endpoints were measured on 1
male pup/litter, thus accounting for litter issues.
Bisphenol A exposure did not affect dam body weights
during gestation or lactation, gestation duration, litter size,
number of male and female pups, or final dam body and
organ weights. [Data were not shown.] Body and organ
weights of male offspring at 21 days and 8 weeks of age,
behavior in open-field testing, spontaneous motor activity,
and performance in the elevated-plus maze were also
unaffected by bisphenol A exposure. [Data were not
shown by study authors.] Bisphenol A had no significant
effect on performance in the passive avoidance test,
although tendencies for increased latency were observed.
In active avoidance testing, rats from the bisphenol A
group had significantly (Po0.01) fewer correct avoidance
responses during the first, second, and third of five
sessions, and failure of avoidance was significantly
increased [B2.5% in the bisphenol A group compared
to 0.2% in controls]. In contrast to control rats, bisphenol
A-treated rats did not show an increase in locomotion
following a challenge with trans-2-phenylcyclopropylamine
hydrochloride. The number of rearings following 2phenylcyclopropylamine
hydrochloride exposure did not
differ significantly between rats from the bisphenol A and
control groups. The study authors concluded that perinatal
exposure of rat dams to bisphenol A at concentrations
Birth Defects Research (Part B) 83:157–395, 2008