Prenatal exposure to PCBs

An association between prenatal exposure to PCBs and deficits in childhood intellectual function was described for children born to mothers who had eaten large quantities of contaminated fish (Jacobson Jacobson, 2002). The bulk of the evidence from human studies indicates that PCBs pose little hazard to human health except in situations where food is contaminated with high concentrations of these congeners. 

Summarizing, the main effects of. prenatal exposure to PCBs in the species studied were low birth weights, high peri- and postnatal mortalities and poor growth rates of the offspring. Exposure to PCBs very early in pregnancy could inhibit implantation. 

More recently, it had been reported that prenatal exposure to PCBs and their heat degradation product dibenzofurans resulted in babies born with retarded growth with dysmorphic physical findings, delayed cognitive development, increased otitis media, and more behavioral problems than in unexposed children (Guo et al., 2004b). 

L. Birnbaum, Endocrine effects of prenatal exposures to PCBs, dioxins, and other xenobiotics Implications for policy and future research. Environ. Health Perspect. 102(8) 676, 1994. 

Since adverse health effects are of concern, particularly for prenatal exposure to PCBs, Lackmann et al. (1999) investigated the influence of maternal age and duration of pregnancy on serum concentrations of PCBs in full-term neonates. Blood samples were taken from 80 full-term German neonates within the first 12 hours of life, before the first oral feeding. The median serum concentration of total PCBs was... 

Stewart P, Darvill T, Lonky E, et al. 1999. Assessment of prenatal exposure to PCBs from maternal consumption of Great Lakes fish An analysis of PCB pattern and concentration. Environ Res 80 S87-S96. 

Higher PCB levels were associated with less muscle tone and activity and hyporeflexia. Prenatal exposure to PCBs (levels in milk at birth) was associated with a significant decrease in PDI scores at the ages of 6 and 12 months. 

Darvill T, Lonky E, Reihman J, et al Prenatal exposure to PCBs and infant performance on the Fagan test of infant intelligence. Neurotoxicology 21 1029-1038, 2000 Fitzgerald EF, Weinstein AL, Youngblood LG, et al Health effects three years after potential exposure to the toxic contaminants of an electrical transformer fire. Arch Environ Health 44 214-221,1989... 

Chen Y-CJ, Hsu C-C Effects of prenatal exposure to PCBs on the neurological function of children a neuropsychological and neurophysiological study. Dev Med Child Neurol 36 312-320, 1994... 

Researchers argue about the effects of prenatal exposure to PCBs on brain development and later childhood cognitive performance. Some studies find effects and some don t. Some studies do not involve direct measurements of PCBs in blood but rely on surrogate (proxy) measurements, such as consumption of fish from contaminated waters. It s also difficult to locate a population in which fetuses have been exposed to PCBs but not to other toxins. It may be that cognitive effects are limited to certain kinds of brain-work not revealed by current tests. We don t know yet. But given all the evidence that exists about serious effects in animals and human adults, and given the general axiom that the human fetus is about a hundred times more vulnerable than adults to toxins, it s reasonable to say that the question of the effects of prenatal exposure to PCBs is not yet resolved. 

PCBs are known to be potent immunotoxins, producing in many animal species atrophy in the thymus gland, a major gland of the immune system. Autism is characterized by immune system parameter deviations, and so it s possible that autism may be a consequence of an autoimmune process in the developing brain resulting from prenatal exposure to PCBs.74... 

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