Pesticide Exposure and Self-reported Parkinson's Disease in the Agricultural Health Study

Abstract

Previous studies based on limited exposure assessment have suggested that Parkinson's disease (PD) is associated with pesticide exposure. The authors used data obtained from licensed private pesticide applicators and spouses participating in the Agricultural Health Study to evaluate the relation of self-reported PD to pesticide exposure. Cohort members, who were enrolled in 1993-1997, provided detailed information on lifetime pesticide use. At follow-up in 1999-2003, 68% of the cohort was interviewed. Cases were defined as participants who reported physician-diagnosed PD at enrollment (prevalent cases, n = 83) or follow-up (incident cases, n = 78). Cases were compared with cohort members who did not report PD (n = 79,557 at enrollment and n = 55,931 at follow-up). Incident PD was associated with cumulative days of pesticide use at enrollment (for highest quartile vs. lowest, odds ratio (OR) = 2.3, 95% confidence interval: 1.2, 4.5; p-trend = 0.009), with personally applying pesticides more than half the time (OR = 1.9, 95% confidence interval: 0.7, 4.7), and with some specific pesticides (ORs > or = 1.4). Prevalent PD was not associated with overall pesticide use. This study suggests that exposure to certain pesticides may increase PD risk. Findings for specific chemicals may provide fruitful leads for further investigation.

Epidemiology and etiology of Parkinson’s disease: a review of the evidence

“…In analyses of specific pesticides among incident cases, ORs above 1.4 (although non-significant) were obtained for dicamba, trifuralin, butylate, and 2,4,5-trichlorophenoxyacetic acid (herbicides), for lindane and phorate (insecticides), for chlorothalonil and benomyl (fungicides), and for methyl bromide (fumigant) [332]. Exposure to paraquat was associated with non-significantly increased PD risk in prevalent but not in incident cases [332].…”

“…Only the AHS [332] and the MSA [324] studies performed in-depth assessment of pesticide exposure in populations with high exposure prevalence. However, despite collection of detailed information regarding frequency, duration, use of specific pesticides as well as protection equipment, misclassification of exposure may still occur.…”

“…In the Agricultural Health Study (AHS) [332] When exposure to pesticides was analyzed as a dichotomous variable (ever versus never), no significant associations were detected. In analyses of specific pesticides among incident cases, ORs above 1.4 (although non-significant) were obtained for dicamba, trifuralin, butylate, and 2,4,5-trichlorophenoxyacetic acid (herbicides), for lindane and phorate (insecticides), for chlorothalonil and benomyl (fungicides), and for methyl bromide (fumigant) [332].…”

“…Most studies suffered from lack of detailed exposure assessment and low frequency or intensity of the exposure, precluding analyses of particular pesticides and dose-response relationships. Recent studies conducted in populations highly exposed to pesticides [324,332] represent an improvement. As indicated in reviews covering the area [362-364, 372, 373, 365, 374] however, causation has not been established between pesticides and PD.…”

Paraquat and Parkinson's disease

“…The Agricultural Health Study 16 made a cohort investigation of over 79 500 agricultural workers from North Carolina and Iowa. The participants were recruited between 1993 and 1997 and followed-up to 1999-2003.…”