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Studies on populations of pregnant women who consumed fish
exposed to agents, and populations from the general public
showed adverse effects of chemicals on children's nerve
development. However, the effects could be counteracted by
breast feeding according to the studies in Lake Michigan,
Holland and Spain, or by favorable home environment according to
the Dutch and Spanish studies. Daniels et al. (2003) suggested
that discrepancy in results from different research centers is
due to uncontrolled factors such as foods or exposure to mercury
or lead. Riva et al. (2004) did not find colostrum PCB level and
visual function of babies at 12 months of age after adjustment
for confounders. Thus, the studies on populations of pregnant
women who consumed fish exposed to agents, and populations from
the general public remain inconclusive. The effects of chemical
exposure seemed to be mitigated by breast feeding or good home
environment, but little is known about details.
Effects of prenatal exposure to environmental tobacco smoke,
polycyclic aromatic hydrocarbons and organophosphate pesticides
on body weight, body height, head circumference and attention
performance of neonates were reported in a synchronic study and
case-control study. The DDT level in breast milk was also found
to be a deleterious factor in development of the child: it was
correlated inversely with mental development of the child and
positively with the percentage of mentally retarded children.
In spite of accumulation of epidemiologic findings on the
association of PCBs and pesticides with infantile nerve
development by advance of cohort studies, clear causal
relationship cannot yet be inferred because of the diversity of
chemical substances chosen for evaluation of exposure level, as
well as measures of children's development. No Japanese subject
was included in any of the study mentioned above. It is
recommended to organize a longitudinal research program on a
population of Japanese pregnant women covering the entire period
from gestation to the schooling age of their children in order
to investigate effects of their pre- and postnatal exposure to
PCBs and dioxins. Such a program should be designed as a
prospective cohort study which permits taking into account
various chemicals and living environment that may affect the
nerve development of children.
[Literature]
Table 2.10.1:
Cohort studies on the relationship of endocrine disruptors with
infantile nerve development
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