Environmental exposure to pesticides and the risk of Parkinson's disease in the Netherlands

- Environmental exposure to four a priori selected pesticides was not significantly associated with PD.
- A broad screen revealed increased PD risk for a group of 21 (related) pesticides.
- Results were suggestive for an association between bulb cultivation and PD risk.
- Findings should be seen a hypothesis generating and as leads for future research.

BackgroundExposure to pesticides has been linked to Parkinson's disease (PD), although associations between specific pesticides and PD have not been well studied. Residents of rural areas can be exposed through environmental drift and volatilization of agricultural pesticides.ObjectivesOur aim was to investigate the association between lifetime environmental exposure to individual pesticides and the risk of PD, in a national case-control study.MethodsEnvironmental exposure to pesticides was estimated using a spatio-temporal model, based on agricultural crops around the residential address. Distance up to 100 m from the residence was considered most relevant, considering pesticide drift potential of application methods used in the Netherlands. Exposure estimates were generated for 157 pesticides, used during the study period, of which four (i.e. paraquat, maneb, lindane, benomyl) were considered a priori relevant for PD.ResultsA total of 352 PD cases and 607 hospital-based controls were included. No significant associations with PD were found for the a priori pesticides. In a hypothesis generating analysis, including 153 pesticides, increased risk of PD was found for 21 pesticides, mainly used on cereals and potatoes. Results were suggestive for an association between bulb cultivation and PD.ConclusionsFor paraquat, risk estimates for the highest cumulative exposure tertile were in line with previously reported elevated risks. Increased risk of PD was observed for exposure to (a cluster of) pesticides used on rotating crops. High correlations limited our ability to identify individual pesticides responsible for this association. This study provides some evidence for an association between environmental exposure to specific pesticides and the risk of PD, and generates new leads for further epidemiological and mechanistic research.