In Hebron, a small farming town in New York's Washington county, residents including farmer Gordon Chaplin believe long-term exposure to the herbicide paraquat has caused a cluster of Parkinson's disease cases among their community. Chaplin, 81, developed symptoms nearly a decade ago and was later diagnosed with the incurable degenerative brain disease, despite having no family history or genetic risk factors; he and his wife, Sarah Teale, believe decades of paraquat spraying on their 200-acre farm are to blame. The case has fuelled fresh scrutiny of the widely used weedkiller, which is already banned in more than 70 countries, and has prompted campaigners to press New York to follow suit.

Teale has identified at least 14 people with Parkinson's living near their home along a seven-mile stretch of highway she calls "Parkinson's Valley", with dozens more cases found in neighbouring towns. Paraquat use in the US nearly doubled between 2014 and 2018 to at least 11m pounds annually, with New York growers spraying almost 149,000lb in 2018 alone. This year 14 US states introduced bills to restrict or ban the chemical, but only Vermont succeeded; New York's proposed ban stalled amid a budget standoff, though its sponsor, assembly member Linda Rosenthal, has vowed to push it through in the next legislative session.