Airborne Trichloroethylene Exposure and Parkinson’s Disease Risk in Medicare Beneficiaries
Brittany Krzyzanowski1, Irene Faust1, Susan Searles Nielsen2, Brad Racette1
1Barrow Neurological Institute, 2Washington University in St Louis
Objective:
To test for nationwide and region-specific associations between airborne trichloroethylene (TCE) and Parkinson’s disease (PD).
Background:
Prior epidemiology studies suggest that occupational exposure and residence near TCE contaminated water may increase the risk of PD. However, the role of environmental airborne TCE exposure in PD risk remains relatively unknown.
Design/Methods:
We performed a nationwide case-control study of incident PD in 1,559,135 Medicare beneficiaries (252,700 with incident PD in 2016-2018) and their exposure to residential airborne TCE in 2005 based on the 9-digit zip code for their earliest residence. We used logistic regression, circular cartograms, SaTScan, and spatial correlation analysis to investigate the risk of PD in relation to airborne TCE and to identify geospatial patterns of risk.
Results:
We found an association between airborne TCE and PD risk with an odds ratio (OR) of 1.23 (95% CI 1.11-1.36) when comparing individuals with the highest TCE levels (10.0-58.0ppb) to the lowest levels (0.17-0.25ppb). At the highest deciles of airborne TCE the relationship between TCE and PD appeared to plateau, but the overall association remained positive and dose dependent. Additionally, we observed the TCE-PD association primarily in urban areas. Spatial correlation mapping identified a robust multi-county high-TCE/high-PD cluster in the District of Columbia where the relative risk of PD was 1.46 (95% CI 1.30-1.57) compared to the rest of the nation. We also found associations between airborne TCE and PD risk in two PD clusters with low to moderate TCE levels in West Virginia (OR 1.89; 95% CI 1.12-3.21) and on the New Jersey-Pennsylvania border (1.27 95% CI 1.04-1.55) when comparing the highest decile of TCE exposure to the lowest decile.
Conclusions:
We identified a robust nationwide association between airborne TCE and PD risk largely driven by exposure in urban populations, suggesting that airborne environmental TCE exposure may also contribute to incident PD risk.