Here's some of the research linked in the article.

"Rotenone, Paraquat, and Parkinson’s Disease" - https://pmc.ncbi.nlm.nih.gov/articles/PMC3114824/

"In 110 PD cases and 358 controls, PD was associated with use of a group of pesticides that inhibit mitochondrial complex I [odds ratio (OR) = 1.7; 95% confidence interval (CI), 1.0–2.8] including rotenone (OR = 2.5; 95% CI, 1.3–4.7) and with use of a group of pesticides that cause oxidative stress (OR = 2.0; 95% CI, 1.2–3.6), including paraquat (OR = 2.5; 95% CI, 1.4–4.7)."

"Agricultural paraquat dichloride use and Parkinson's disease in California's Central Valley" - https://pubmed.ncbi.nlm.nih.gov/38309714/#full-view-affiliat...

"Ambient paraquat exposure assessed at both residence and workplace was associated with PD, based on several different exposure measures. The PD patients both lived and worked near agricultural facilities applying greater amounts of the herbicide than community controls. For workplace proximity to commercial applications since 1974, working near paraquat applications every year in the window [odds ratio (OR) = 2.15, 95% confidence interval (CI) = 1.46, 3.19] and a higher average intensity of exposure [per 10 pounds (4.54 kilograms), OR = 2.08, 95% CI = 1.31, 3.38] were both associated with an increased odds of PD. Similar associations were observed for residential proximity (duration: OR = 1.91, 95% CI = 1.30, 2.83; average intensity: OR = 1.72, 95% CI = 0.99, 3.04). Risk estimates were comparable for men and women, and the strongest odds were observed for those diagnosed at ≤60 years of age."

"Department of Pesticide Regulation Releases Preliminary Findings from Review of Environmental and Human Health Studies Related to the Use of the Pesticide Paraquat" - https://www.cdpr.ca.gov/2024/12/30/department-of-pesticide-r...

"DPR’s preliminary scientific evaluation found that the current registered uses of paraquat in California may adversely affect non-target organisms, including birds, mammals and aquatic organisms, with the most significant risks to birds. Additional mitigation measures, beyond current restrictions on paraquat use currently in effect, may not feasibly reduce these environmental impacts to acceptable levels.

Consistent with United States Environmental Protection Agency’s (U.S. EPA) 2019 review, DPR’s review of existing human health studies does not indicate a causal association between paraquat exposure and Parkinson’s disease."