Methodological considerations in behavioral toxicology in infants and children.

Abstract

The effect of exposure to neurotoxic substances on cognitive and behavioral development has become an important research focus within developmental psychology in recent years. Research design considerations are critically important in these studies, because random assignment and experimental control of extraneous influences are not possible and effects are often subtle and not seen in every exposed individual. Oversampling from the most highly exposed individuals is usually needed to ensure detection of toxic effects. Valid and reliable assessment must be made of important potential confounders, yet control variables must not be so confounded with exposure as to obscure toxic effects. In the assessment of developmental outcome, apical measures may provide the greatest sensitivity, and narrow-band tests, more information about the specific nature ofthe impairment. Dose-response analyses can help determine the lowest exposure levels at which deficits are seen (thresholds).