Polychlorinated biphenyls (PCBs) and neurological development in children:a systematic review

Background-Polychlorinated biphenyls (PCBs) are complex mixtures of persist ent contaminants that are widespread in the environment. Newborns are expos ed across the placenta and through breast feeding. Experimental animal stud ies have indicated that PCBs are neurotoxic. The neurological effects of th ese compounds on children are not clear. Methods-A systematic review of literature on the relation between neurologi cal development in children and exposure to polychlorinated biphenyls. Results-Seven follow up studies evaluated the effect of prenatal exposure t o PCBs. Two of these studies evaluated highly exposed children. In newborns , an increase of the abnormal reflexes was observed in all four studies eva luating it. During the first months of life, a decrease in motor skills was observed in four of the five studies that investigated psychomotor develop ment; deficits in the acquisition of cognitive skills were observed only in one study assessing non-highly exposed populations. At 4 years of age, an effect on the cognitive areas was observed in four of the five studies that evaluated it. Postnatal exposure to PCBs through breast feeding was not cl early related to any effect on neurological development. Conclusions-These studies suggest a subtle adverse effect of prenatal PCBs exposure on child neurodevelopment. Differences in study design, inconsiste ncy in some of the results, and the lack of adequate quantitative exposure data, do not allow the derivation of the degree of risk associated with neu rodevelopmental effects at current levels of exposure.