Assessing cumulative radon decay products in blood samples as a biological proxy for lung cancer risk: a matched...

Lung cancer is the most common malignancy among Iraqi males, yet comprehensive radon exposure data remain scarce. This matched case-control study investigated the cumulative burden of long-lived radon decay products (²¹⁰Pb/²¹⁰Po) in dried blood samples as a biological proxy for radon exposure in Babylon Governorate, Iraq. Blood samples were collected from 38 lung cancer patients and 38 age- and sex-matched healthy controls, lyophilized, and analyzed using CR-39 solid-state nuclear track detectors over a 120-day exposure period. Linear mixed-effects modelling, accounting for the matched design and potential confounders, revealed significantly higher radon decay product concentrations in cases compared to controls (adjusted mean difference: 67.95 Bq/m³; 95% confidence interval (CI): 57.43-78.46; p < 0.001). Age was positively associated with concentration (7.56 Bq/m³ per year; p < 0.001), reflecting cumulative environmental exposure. Male smokers showed significantly higher concentrations than male non-smokers (24.9 Bq/m³; p = 0.039), while no significant smoking-related difference was observed in females. These findings validate dried blood samples with CR-39 detectors as a sensitive tool for assessing cumulative radon progeny burden and underscore the urgent need for targeted radon mitigation strategies in Iraq, particularly for smokers and older populations.