Ambient Trichloroethylene Exposure and Parkinson Disease Risk in Medicare Beneficiaries

BACKGROUND AND OBJECTIVES: Trichloroethylene (TCE) is an important environmental contaminant in the United States due to widespread use industrially. Epidemiologic studies suggest that occupational exposure to TCE and TCE-contaminated drinking water may increase the risk of Parkinson disease (PD). The aim of this study was to investigate the nationwide relationship between ambient TCE and PD risk. METHODS: . We also mapped the nationwide geospatial pattern of ambient TCE and then explored high-resolution local PD risk patterns using MapGAM for the 10-mile radius around the top 3 TCE-emitting facilities from the EPA's Toxic Release Inventory in 2002. RESULTS: ). We observed high levels of ambient TCE in the rust belt region of the United States and several smaller areas throughout the nation. Our MapGAM results suggested greater PD risk in the area surrounding 2 of the 3 highest ambient TCE-emitting facilities, one of which demonstrated a marked decreasing gradient of risk with increasing distance from the facility. DISCUSSION: We identified a positive association between ambient TCE and PD risk, suggesting that TCE may contribute to PD. We identified relatively higher risk of PD near 2 TCE-emitting facilities. This study was limited to Medicare-aged individuals.