High pesticide exposure events and central nervous system function among pesticide applicators in the Agricultural Health Study

Abstract

While acute pesticide poisoning can be associated with persistent adverse central nervous system (CNS) effects, little is known about the effect of one or more episodic and unusually high pesticide exposure events (HPEE) that typically do not result in acute poisoning. The objective of this investigation was to examine the association between ever having an HPEE and CNS function among licensed pesticide applicators enrolled in the Agricultural Health Study (AHS). In 2006-2008, 693 male participants with no history of a physician-diagnosed pesticide poisoning completed nine neurobehavioral tests to assess memory, motor speed, sustained attention, verbal learning, and visual scanning and processing. Information on ever having an HPEE and pesticide poisonings was obtained from previous AHS interviews. Associations between ever having an HPEE and neurobehavioral outcomes were estimated with linear regression controlling for age and outcome-specific covariates. A history of ever having an HPEE was reported by 156 (23%) participants. Adverse associations were observed between ever having an HPEE and two of the nine neurobehavioral tests. On a test of visual scanning and processing (Digit-Symbol), participants who ever had an HPEE were 4.2 s slower (95% CI: -7.27, -1.11) than those without an HPEE, equivalent to the effect of 3.9 years of age in this population. On a test of visual scanning and motor speed (Sequences A), participants who ever had an HPEE were 2.5 s slower (95% CI: -4.53, -0.41) than those without an HPEE, equivalent to the effect of 3.9 years of age. No significant associations were observed between participants who ever had an HPEE and the remaining neurobehavioral tests. One or more HPEE may contribute to adverse CNS outcomes independent of diagnosed pesticide poisoning.