Risk assessment of the developmental neurotoxicity of lead.

Lead has long been recognized as a developmental neurotoxicant. Although no reasonable doubt exists about this qualitative characterization, quantitative aspects of the developmental neurotoxicity of lead have been more difficult to resolve. This paper focuses on two key issues in a risk assessment of lead: the blood lead level of concern, i.e., the lowest level of exposure associated with neurotoxic effects in children, and the magnitude and implications of such effects. The distinction between a threshold and a level of concern is also discussed, along with the issue of whether a threshold exists for lead-induced health effects.