In vitro analysis of the suitability of different biodosimetric techniques for the study of human biomonitoring with low concentrations of Radon-222.

Human exposure to radionuclides from naturally occurring radioactive material (NORM) varies according to daily activities and proximity to natural radioactive sources in the environment. Studies conducted in municipalities of Recife's metropolitan region detected radionuclides, such as radon, in food, soil, atmosphere, and well water. However, human biomonitoring in this population remains necessary. This study evaluates the suitability of biodosimetric techniques to be applied in regions of NORM occurrence and investigates the correlation between DNA damage and low Rn222 concentrations. Peripheral blood samples were exposed in vitro to Rn222 at 19.4, 26.0, 66.1, and 93.3 KBq/m3, plus an unexposed control. Three techniques were applied: Dicentric Chromosome, Micronucleus, and Comet Assay. In the dicentric assay, there was a significant increase (p < 0.001) in dicentric frequency in the irradiated samples compared to the control. Although an absolute increase was also observed among the exposed groups, in accordance with the activity concentrations, this difference was not statistically significant (p > 0.05). The micronucleus assay, there was also a statistical difference between the irradiated samples and the control samples (p < 0.05) but showed limited sensitivity to dose-response dependence. The comet assay confirmed the genotoxic effect of radon on the cells, as demonstrated by increased DNA strand breaks and relaxation in the exposed samples. Overall, the three techniques effectively differentiated exposed from unexposed samples, demonstrating their potential for radiation exposure screening. Although the dicentric assay demonstrated higher sensitivity, the findings highlight the importance of integrated biodosimetric approaches in specific scenarios of low-dose exposure.