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

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 < or =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.

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

“…In contrast to the Californian study [323], this study found a stronger association in individuals with late age at onset (> 65 years) [324].…”

“…Some case-control studies reported results for specific categories of pesticides, such as herbicides, insecticides, or fungicides, rather than pesticides overall. Of 18 studies that analyzed exposure to herbicides, 10 found increased risk of PD, either for herbicides as a group of substances, or for specific herbicides, such as paraquat, nitrile herbicides or 2,4-Dichlorophenoxyacetic acid [153,154,290,293,302,304,[321][322][323][324], with ORs ranging between 1.6 and 5.8. The other 8 studies reported no association between herbicides and PD [131,143,292,299,301,315,316,325].…”

“…Four other studies that assessed paraquat specifically, however, found no association [292,301,304,316,317], although one [304] reported increased risk of PD following exposure to 2,4-Dichlorophenoxyacetic acid (OR 2.59, 95% CI 1.03-6.48). A population-based Californian study [323] assessed historical pesticide residential exposure through a combination of interviews, geographical information system (GIS), and California Pesticide Use Reports. Combined exposure to maneb and paraquat (OR 1.75, 95% CI 1.13-2.73), but not to paraquat alone (OR 1.01, 95% CI 0.71-1.43) was associated with increased risk [323].…”

“…A population-based Californian study [323] assessed historical pesticide residential exposure through a combination of interviews, geographical information system (GIS), and California Pesticide Use Reports. Combined exposure to maneb and paraquat (OR 1.75, 95% CI 1.13-2.73), but not to paraquat alone (OR 1.01, 95% CI 0.71-1.43) was associated with increased risk [323]. Another study was performed among farmers, taking advantage of the French health insurance system for agriculture workers (Mutualite Sociale Agricole-MSA) [324].…”

Paraquat and Parkinson's disease

“…In another recent study, Costello et al 21,22 used a new approach for the assessment of pesticide exposure, incorporating California Pesticide Use Reporting (PUR) data and the geo-coding of residential addresses. The study considered only the use of the pesticides paraquat and maneb; information on exposure to other agricultural chemicals was not sought.…”