BACKGROUND/OBJECTIVES: There is consistent and growing interest in assessing the association between environmental exposure to radon and the risk of childhood cancer. However, previous studies have been largely equivocal. Therefore, we sought to evaluate the association between indoor radon exposure and the incidence of pediatric lymphoma in Texas, a state characterized by a large population-based cancer registry and variable concentrations of radon.
DESIGN/METHODS: Information on childhood lymphoma cases was obtained from the Texas Cancer Registry (n=2,147) for the period 1995-2011. Denominator data were obtained from the 2000 United States Census. Exposure to radon was estimated using data from the Texas Indoor Radon Survey. Specifically, arithmetic mean radon concentrations (picoCuries/liter; pCi/l) were obtained from 13 geologic regions in the state and linked to the residence at diagnosis. Exposure was assessed both on a continuous scale and dichotomously (<90th percentile [low exposure] vs. ≥90th percentile [high exposure]). Poisson regression was used to generate incidence rate ratios (IRR) and 95% confidence intervals (CI) adjusted for sex, race/ethnicity, and area-level poverty. We evaluated the following lymphoma outcomes: Hodgkin (HD; n=1,248), Burkitt Lymphoma (BL; n=241), and Non-Hodgkin excluding Burkitt Lymphoma (non-BL NHL; n=658).
RESULTS: The mean radon concentration across regions was 1.24 pCi/l (range: 0.25-3.30). For every one pCi/l increase in radon exposure, there was a modest, but non-significant, increase in the incidence of non-BL NHL (IRR [95% CI]: 1.07 [0.93-1.24]). Additionally, areas with high radon concentrations had a 26% higher incidence of non-BL NHL (95% CI: 0.88-1.81) compared with areas of low radon concentrations. Associations were not detected for HD or BL.
CONCLUSION: Overall, there was little evidence to suggest radon is strongly associated with childhood lymphoma incidence. However, the incidence of non-BL NHL was modestly increased in areas of the highest concentrations.
