Assessment of excess lifetime cancer risk and risk of lung cancer due to exposure to radon in a middle eastern city in Iran

Abstract Objective To assess the excess lifetime cancer risk and lung cancer risk due to exposure to 222Rn at homes, stone cutting and processing plants, and stone mines. Methods 222Rn concentration was measured in 74 sample sites. Sampling was conducted using Alpha Track, comprising CR-39 polymer film. The detectors were placed at the height of 1.00–1.50 m from the floor and away from windows and sunlight per the US. EPA guidelines. The detectors were retrieved after being exposed to 222Rn for the period of three months and then etched in a 6.25 mol/L NaOH solution at 90 °C for 4 h. The results were used to assess the excess lifetime cancer risk (ELCR) and lung cancer risk (LCR). Results The findings showed that the ELCR at homes, stone cutting and processing plants, and stone mines for the mean levels of 222Rn were 0.49%, 0.15%, and 0.15%, respectively. The ELCR values for all sampling sites were lower than the U.S. EPA action level. The number of lung cancer cases in the Neyriz due to the effective dose received by residents for the mean, maximum, and 95th percentile was estimated to be 1.6, 3.6, and 3.1 per year, respectively. The number of lung cancer cases per 106 population due to exposure to mean concentration for stone cutting and processing plants was 10.53, 15.79, and 14.49, respectively. These values for stone mines were 10.39, 26.76, and 18.87, respectively. The results have shown that LCR values were below the range recommended by ICRP. Conclusions Overall, the ELCR, because of long-term exposure to 222Rn and its progeny levels, does not pose a significant threat to residents and workers. The LCR associated with radon exposure was low in three sampling sites that could be considered safe for both residents and workers.