METHODOLOGICAL CONSIDERATIONS IN BEHAVIORAL-TOXICOLOGY IN INFANTS ANDCHILDREN

The effect of exposure to neurotoxic substances on cognitive and behav ioral development has become an important research focus within develo pmental 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 eff ects are often subtle and not seen in every exposed individual. Oversa mpling from the most highly exposed individuals is usually needed to e nsure detection of toxic effects. Valid and reliable assessment must b e 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 th e specific nature of the impairment. Dose-response analyses can help d etermine the lowest exposure levels at which deficits are seen (''thre sholds'').