Agricultural paraquat dichloride use and Parkinson's disease in California's Central Valley.
Level 4 - case-series / case-control
Population-based case-control study
PubMed 38309714 · doi:10.1093/ije/dyae004
What was done
Authors conducted a population-based case-control study in three California Central Valley counties comparing 829 Parkinson's disease (PD) patients with 824 community controls. Residential and workplace ambient exposure to commercial paraquat dichloride applications since 1974 was modeled using California Pesticide Use Reporting data and historical land-use maps. They assessed presence, duration, and average intensity of exposure across four time windows.
What was found
Ambient exposure to paraquat at both residence and workplace was associated with increased PD odds: - Workplace exposure every year since 1974: OR = 2.15 (95% CI: 1.46 to 3.19). - Workplace average intensity per 10 pounds/acre/year: OR = 2.08 (95% CI: 1.31 to 3.38). - Residential proximity duration: OR = 1.91 (95% CI: 1.30 to 2.83). - Residential average intensity: OR = 1.72 (95% CI: 0.99 to 3.04). - Risk estimates were similar in men and women, with the strongest associations in individuals diagnosed at 60 years of age or younger.
Why it matters
This adds large-scale epidemiological evidence that ambient environmental and occupational proximity to commercial paraquat applications increases Parkinson's disease risk, particularly for early-onset cases.
Limits
Exposure was derived from GIS and pesticide reporting models rather than personal dosimetry or biomarkers, allowing potential exposure misclassification. Case-control designs are subject to recall and selection biases, and specific risk numbers for the subset diagnosed at or before age 60 were not reported in the abstract.
Cited by
- supports A study by Kimberly Paul and Beate Ritz from UCLA showed that living or working near areas where paraquat is sprayed is associated with a doubling of Parkinson's disease risk.
- supports Farmers who work directly with Paraquat have a 150% increased risk of Parkinson's disease, and people living or working near where Paraquat is sprayed have a 100% increased risk.