A Monte Carlo simulation of unmitigated risk of radon exposure from soil and groundwater around Maiganga Coal Mine, North-Eastern Nigeria

Radon has become a significant health concern globally due to its health hazard to the population. Radon and its progenies contribute 50% of the total geogenic radiation dose; therefore, it is the principal contaminant that induces gene mutation, amplifying the non-smoking cancer risk of the lungs and stomach through inhalation and ingestion. Hitherto, the Monte Carlo simulation application for predicting the health risk of radon gas attributed to inhalation and ingestion from coal mine openings was not established. Here, we investigated the effect of coal mining in enhancing the emission and dissolution of groundwater radon in experimental and control positions and the resultant carcinogenic health risk. The result showed variable concentrations of 222Rn exceeding the exposure limit, suggesting pollution aggravated by coal mining. Ingestion and inhalation of 222Rn in the groundwater showed that 98% of the total effective dose exceeds the reference values of 1150 μSv/y. In contrast, over 53% of the total effective dose exceeds 20000 μSv/y occupational dose limits. The elevated risks were validated by the 5th, 50th, and 95th percentiles of the cumulative probabilities for the excess lifetime cancer risk using the Monte Carlo simulation. All the cancer risk values evaluated are higher than the recommended limit of 0.00375 provided by ICRP and UNSCEAR. Mandatory incorporation of a thermoluminescent dosimeter (TLD) badge among the miner’s protective equipment is essential for monitoring radiation hazards.