Poisoning young minds.

For some neurotoxic chemicals, neurobehavioral effects are now considered to be among the most sensitive end points yet detected, particularly if exposures occur during critical windows of vulnerability. Chemically induced problems with perception and cognitive ability in children can be hard to identify; teasing them out of a host of genetic and sociocultural influences is a difficult task. Today, most data on environmentally relevant neurobehavioral effects in children are concentrated in three chemicals: lead, methylmercury, and polychlorinated biphenyls. But mounting evidence of the neurobehavioral effects of chemicals along with growing public concern over pediatric mental health problems such as attention deficit/hyperactivity disorder dictates that scientists and legislators improve test methods, explore mechanisms, and develop appropriate strategies for risk assessment and policy making.