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Advisory Committee on Health Effects of Endocrine Disruptors
The Supplement II to the Intermediary Report
1.4.2.2_10 |
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(ii) Infants from mothers exposed to agents accumulated in fish
Studies have been made on women for intake during gestation of
fish from Lake Ontario and Michigan with accumulated PCBs via
food chain. Fein et al. (1984) pointed out effects on body
weight and head circumference of newborns. Jacobson et al.
(1985, 1990, 1996) studied the relationship of nerve development
of children 5 months to 11 years of age with prenatal PCB
exposure and breast feeding period. Jacobson et al. (2002)
further evaluated their cognitive development at 4 and 11 year
of age, and analyzed the effects of prenatal PCB exposure with
breast feeding period, mother's IQ, HOME (Home Observation for
Measurement of Environment) and sex as controlling factors of
confounding. Comparison of children groups with breast feeding
periods less than 6 weeks and equal to or more than 6 weeks
revealed a significant correlation of cognitive development and
prenatal PCB exposure only in the former group, while response
to mental rotation tasks were correlated to prenatal PCB
exposure only in the latter. No sex difference was observed in
the pattern of delay in cognitive development. Furthermore,
Jacobson et al. (2003) evaluated the children at 4 and 11 years
of age (154 and 148 cases, respectively) for attentional
function, and found a inverse association with prenatal PCB
exposure for children not breast-fed (chiefly fed with
artificial milk). These children showed greater impulsivity,
poorer concentration, and poorer verbal, pictorial, and auditory
working memory. As for the curing influence of breast feeding on
the adverse effects of PCB exposure on the nerve system, both of
their papers reported that it was difficult to distinguish the
effects of nutrients in breast milk and those of intellectual
stimulation by breast-feeding mothers.
Women consuming fish with PCBs accumulated through food chain
were also studied in Oswego, New York. Lonky et al. (1996) and
Stewart et al. (2000) found delayed development of the
autonomous nerve system in severely exposed children. Stewart et
al. (2003) evaluated the cognitive development of 212 cases in
the Oswego study by McCarthy test at 38 months and 54 months of
age to examine association with prenatal exposure to PCB
(measured by cord blood PCB) and methylmercury (MeHg). The
McCarthy general cognitive index (GCI) score was significantly
correlated with the concentration of highly chlorinated PCBs in
cord blood at 38 months of age (P = 0.012), but no correlation
was observed at 54 months. This suggested that rather severely
exposed children can catch up with unexposed peers by the 54th
month. The researchers also studied the association of prenatal
PCB exposure with impairment of response regulation,
particularly increase of error commission, by continuous
performance test (CPT) on 189 children 4 or 5 years of age, and
observed morphological changes in posterior corpus callosum by
MRI. The association of PCB exposure with response errors was
closer for children with smaller corpus callosum, suggesting
that children with less-than-optimum corpus callosum development
are more susceptible to PCB.
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