Children's cognitive health: the influence of environmental chemical exposures.

The potential exists for developmental exposure of children to myriad chemicals, many of which are known to be neurotoxic. Some, such as the organophosphate pesticides, are specifically designed to attack the central nervous system. Despite the known and suspected risks associated with such exposures, critical aspects of the dose-response relationships are unknown or, at best, poorly characterized for the overwhelming majority of chemicals. Among the major knowledge gaps for most chemicals are the critical window(s) of vulnerability, the threshold or "no observed adverse effect level," and the host/environmental characteristics that modify individual vulnerability. Investigation of the role of genetic polymorphisms in determining vulnerability has barely begun. In the real-world, children are not exposed to a single chemical at a time but to complex mixtures of chemicals, and we have only a minimal understanding of the way in which exposures might interact with one another. Effective medical/environmental treatments for the adverse effects associated with chemical exposures are largely unknown, rendering primary prevention of exposure the most effective strategy for protecting children.