Objective: Parkinson’s disease (PD) is a neurological disorder that is increasing in incidence globally. Recent studies suggest that exposure to low-dose ionizing radiation may be associated with PD risk. We studied the association between occupational radiation exposure and PD mortality in a large U.S. medical worker cohort

Methods: U.S. Radiologic Technologists (USRT) Study participants (mean baseline age 41.0 years, 76.0% female) were followed from response date of the 1st (1983-1989) or 2nd survey (1994-1998) to December 31, 2021 (n=109,113). Estimated radiation absorbed dose to the brain was calculated for the exposure period 1916-2020. PD mortality included PD as any cause of death. Multivariable Poisson regression models were used to calculate excess relative rates (ERR) of PD mortality per 100 mGy, using 10-year lagged cumulative brain-absorbed dose. Multivariable Cox proportional hazards models were used to calculate hazard ratios for PD mortality associated with self-reported work history (decade first worked, total years worked per decade, procedures performed [fluoroscopically-guided interventional (FGI), nuclear medicine], number of times held patients, and ever exceeding exposure limit).

Results: During follow-up of 3,389,435 person-years, 433 PD deaths occurred. A linear dose-response relationship was observed for PD mortality (ERR/100mGy=1.53;95%CI:0.51-3.25), especially in male workers. Ever assisting with FGI procedures was associated with a higher PD mortality risk (HR=1.45;95%CI:1.06-2.00). Participants who assisted with FGI procedures daily post-1980s had a higher PD mortality risk than those who never/rarely assisted post-1980s (HR=2.58;95%CI:1.54-4.32).

Conclusion: Cumulative low-dose radiation exposure and daily assisting with FGI procedures were associated with higher PD mortality. These findings support continued efforts to limit occupational radiation exposure and provide additional support for a role of ionizing radiation in PD etiology.