Proximity to nuclear power plants and total mortality risk in the USA during 2000-2018.

Nuclear power plants (NPPs) are a major source of electricity in the United States, yet concerns persist regarding potential health effects of chronic low-level radiation exposure among nearby populations. Evidence on population-level mortality impacts remains limited. To evaluate the association between long-term exposure to NPPs and all-cause mortality across U.S. counties from 2000 to 2018. A proximity-based exposure was calculated as the sum of inverse distances from each county's population centroid to all active nuclear power plants within 200 km for each year and averaged over a 20-year moving window to account for latency. Using aggregated county-level data in an ecological framework across the United States, associations between nuclear power plant proximity and age- and sex-specific all-cause mortality were estimated using Poisson regression models within a generalized estimating equations (GEE) framework, adjusted for county-level covariates. Positive associations between NPP proximity and all-cause mortality were concentrated in middle- and older-age groups. The largest effect estimates were observed among females aged 55-64 (β = 0.834, 95% CI 0.508, 1.160) and males aged 65-74 (β = 0.757, 95% CI 0.456, 1.058). Coefficients are reported on the log-relative risk scale, corresponding to the change in mortality per one-unit increase in the NPP proximity metric. Based on these associations, if we assumed a causal framework we would attribute approximately 390,000 deaths (95% CI 190,000-590,000), corresponding to 1.7% (95% CI 0.8%-2.6%) of total U.S. mortality in the included counties during the study period, were associated with NPP proximity. In this national analysis, long-term proximity to NPPs was associated with higher all cause mortality. These findings suggest that even low-level exposures may have measurable population health impacts and warrant further investigation.