Overview

• Published Oct. 1 in Neurology, the Medicare-based analysis found about a 10% higher Parkinson’s risk for older adults living in areas with the highest modeled ambient trichloroethylene levels versus the lowest.
• The study examined 221,789 Parkinson’s cases and more than 1.1 million controls diagnosed from 2016 to 2018, assigning exposure using EPA-modeled outdoor TCE concentrations tied to ZIP+4 neighborhoods from 2002.
• Geographic hot spots of higher ambient TCE were identified, notably in parts of the Rust Belt and smaller pockets across the country.
• Risk rose closer to some historically high-emitting facilities, including more than a fourfold increase for residents living one to five miles downwind of a Lebanon, Oregon lithium battery plant compared with those up to 10 miles away.
• Authors stress the findings show an association rather than causation and note limits such as the older cohort and reliance on 2002 ambient data that may not capture lifetime, indoor, or occupational exposures.