Parkinson's Disease and Residential Exposure to Maneb and Paraquat From Agricultural Applications in the Central Valley of California

TLDR

Animal and cell studies suggest pesticides trigger neurodegeneration leading to Parkinson’s disease, but human evidence is limited due to exposure assessment challenges. The authors aimed to develop and validate a GIS‑based exposure assessment tool to estimate historical residential exposure to agricultural pesticides. Using the tool, they enrolled 368 incident PD cases and 341 controls in the Central Valley (1998–2007) and estimated maneb and paraquat exposure from 1974–1999. Exposure to either pesticide within 500 m of home increased PD risk by 75 % (95 % CI 1.13–2.73), with much higher risk among those ≤60 y at diagnosis (OR 4.17 for combined exposure, 95 % CI 1.15–15.16).

Abstract

Evidence from animal and cell models suggests that pesticides cause a neurodegenerative process leading to Parkinson's disease (PD). Human data are insufficient to support this claim for any specific pesticide, largely because of challenges in exposure assessment. The authors developed and validated an exposure assessment tool based on geographic information systems that integrated information from California Pesticide Use Reports and land-use maps to estimate historical exposure to agricultural pesticides in the residential environment. In 1998–2007, the authors enrolled 368 incident PD cases and 341 population controls from the Central Valley of California in a case-control study. They generated estimates for maneb and paraquat exposures incurred between 1974 and 1999. Exposure to both pesticides within 500 m of the home increased PD risk by 75% (95% confidence interval (CI): 1.13, 2.73). Persons aged ≤60 years at the time of diagnosis were at much higher risk when exposed to either maneb or paraquat alone (odds ratio = 2.27, 95% CI: 0.91, 5.70) or to both pesticides in combination (odds ratio = 4.17, 95% CI: 1.15, 15.16) in 1974–1989. This study provides evidence that exposure to a combination of maneb and paraquat increases PD risk, particularly in younger subjects and/or when exposure occurs at younger ages.