Domestic radon exposure and childhood cancer risk by site and sex in 727 counties in the United States, 2001–2018
This research is important because it suggests that radon exposure might pose risks to children's health at levels currently considered acceptable. If confirmed by further studies, it could lead to changes in public health policies, such as lowering the threshold for recommended radon mitigation in homes. It also highlights the need for more research into how radon affects health beyond just lung cancer.
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Highlights
- This study leverages spatiotemporal radon estimates from a geographical machine learning model.
- Annual incident cancer counts were analyzed in a Bayesian spatiotemporal framework.
- Lagged county average radon exposures were associated with higher risk of leukemia.
- Evidence supports future population-based and individual-level investigation.
Abstract
Background
Childhood cancer has few established risk factors and environmental influences are underexplored. This ecologic study investigated the association between domestic radon exposure and childhood cancer risk in a large sample of United States (U.S.) counties.
Methods
Monthly ZIP code-level basement radon estimates from a geographic machine learning model were aggregated annually to counties, analyzed as continuous and dichotomized (cut point: 74 Bq/cubic meter (Bq/m3) or 2.0 picocuries/L (pCi/L)) versions, and lagged by one year. Annual county-level counts of sex- and site-specific (all, leukemia, brain and central nervous system [CNS], and other sites) incident cancer diagnoses among those 0–19 years from 2001 to 2018 were obtained from the National Cancer Institute's Surveillance, Epidemiology, and End Results Program database. Sex- and site-specific counts were modeled as zero-inflated Poisson distributions in a Bayesian spatiotemporal framework and sequentially adjusted for random and fixed confounder effects.
Results
In 727 counties across 14 states, the average population aged 0–19 years was 41,599 people at baseline. Results from fully adjusted spatiotemporal statistical models indicated 1.05 (95% credible interval, CrI: 1.00, 1.09) times higher relative risks (RRs) of leukemia among both sexes and a RR of 1.06 (95%CrI: 1.00, 1.12) in males from a 50 Bq/m3 (1.35 pCi/L) increase in radon concentration the year prior. For radon exposures ≥74 Bq/m3 (2.00 pCi/L) the year prior, RRs were 1.08 (95%CrI: 1.02, 1.15) for both sexes and 1.12 (95%CrI: 1.04, 1.22) for females. No associations were found with other cancer sites or sexes from prior year radon exposures.
Conclusions
County-level childhood leukemia risk in both sexes were associated with average radon levels below U.S. Environmental Protection Agency guidelines recommending mitigation (148 Bq/m3 or 4.00 pCi/L). These findings warrant further investigation using population-based and individual-level study designs.