Study Ties Chlorpyrifos to 2.5-Fold Parkinson's Risk, Fueling U.S. Lawsuits

2 articles · Updated · AboutLawsuits.com · Aug 4

A 2025 Molecular Neurodegeneration study found long-term chlorpyrifos exposure was linked to more than 2.5 times the risk of Parkinson’s disease, based on 829 patients and 824 controls.
Researchers matched California pesticide records with decades of residential and workplace histories, then found risk rose with longer exposure and lab tests in mice and zebrafish showed dopamine-cell loss, inflammation and movement problems.
That evidence is bolstering claims from Gulf War veterans, farmers, applicators, pest-control workers and residents who say repeated exposure preceded Parkinson’s diagnoses years or decades later.
Regulatory scrutiny has already intensified: the EPA banned chlorpyrifos on food crops in 2021, but a federal appeals court later overturned that move while the agency kept weighing further limits.
Older safety evidence has also come under attack, with independent reviews of Dow-backed human and animal studies concluding harmful neurological effects may have appeared even at doses once treated as safe.