Methodological Issues in Specifying Neurotoxic Risk Factors for Developmental Delay: Lead and Cadmium as Prototypes

Abstract

This chapter presents definitions and theoretical frameworks of the disciplines of the study of mental retardation and developmental disabilities. The culmination of early chronic exposure to neurotoxins, such as lead and cadmium may result in the behavioral expression of diminished functional capacity of people. The compounding of irreversible neurotoxic insults even with a normal trajectory of aging is likely to have an exponential, not just an additive, effect. The risks caused by high-level neurotoxic exposures (i.e., encephalopathy, coma, and death) are not controversial; determination of the relative plasticity of the central nervous system (CNS) and the reversibility of such gross neural insults is a matter of empirical research on an established risk factor. It may affect the culturally disadvantaged and other more vulnerable groups in society the most. These are man-made risks that are preventable through environmental regulation. They are unique opportunities for prevention of developmental disabilities, which should not be lost. © 1990 Academic Press, Inc.