Chronic neuropsychological sequelae of occupational exposure to organophosphate insecticides.

The early (immediate and delayed) neurotoxic effects of acute organophosphate intoxication are well documented in the scientific literature; lack of recognition and inappropriate treatment of occupational poisonings continue. Less well understood is the potential development of chronic neuropsychological sequelae from exposures to insecticides. We undertook two cohort studies to assess chronic neuropsychologic effects of insecticide poisoning. Based, in part, on our clinical evaluation of several patients, these studies included: 1) a retrospective cohort study assessing function at least 1 year following moderate to severe poisonings among farm workers; and 2) a prospective cohort study assessing neuropsychological function before and after a season of organophosphate exposures among pesticide applicators. A typical case description, the study design, methodologic problems, and preliminary findings of these ongoing studies are presented.