Analysis of chlorpyrifos exposure and human health: Expert panel report

This report summarizes the deliberations of an eight-member panel of scient ists convened by Dow AgroSciences in cooperation with the U.S. Environmenta l Protection Agency (EPA), The panel was charged with evaluating the scient ific literature on the health effects potentially associated with exposure to the insecticide chlorpyrifos. Specifically, the panel was asked to (1) e valuate human experience data available and address the adequacy of the ava ilable current literature; (2) develop a list of recommendations for epidem iology studies, including appropriate endpoints and study populations, and strengths and weaknesses of each approach; and (3) draft a report to summar ize its recommendations. The panel assessed the quality of the existing epi demiologic literature on chlorpyrifos and specific outcomes such as neuropa thy (including organophosphate induced delayed neurotoxicity), behavior (co gnition and affect), immunologic, and multiple complaints (also referred to as multiple chemical sensitivities). The majority of panel members (five m embers) agreed that the literature reviewed provided little or no scientifi c evidence that chlorpyrifos exposure causes harm to human health other tha n its known cholinergic effects associated with acute poisoning. Those pane l members voting in the minority (three members) agreed that the studies re viewed provided inadequate evidence to preclude the possibility of adverse effects to human health from chlorpyrifos exposure at levels associated wit h its manufacture or professional application. Those voting in the minority suggested further investigation of cohort(s) of workers engaged in either the manufacture or the professional application of chlorpyrifos, or both. C ompared to the general population, these groups have relatively high levels of exposure to chlorpyrifos. The primary health outcomes recommended for s tudy were cognitive and affective disorders, with consideration of the asse ssment of peripheral neuropathy also suggested for at least a subset of the cohort.