Spatial distribution of radon concentrations in groundwater and annual exposure doses in Mirpur District Pakistan

Abstract

Radon (222Rn) is a readily water-soluble naturally occurring carcinogenic gas and poses serious threats to a humans’ health. This study aimed to investigate 222Rn concentration in groundwater and associated health risks. For this purpose, groundwater samples (n = 36) were collected from the Mirpur District (3 towns: Jatlan, Mirpur, and Dadyal), Pakistan. The concentration of 222Rn in groundwater samples was measured by the RAD7 (Durridge Company, USA). Results showed that the average 222Rn concentrations in groundwater were 5.99 ± 1.41, 5.39 ± 0.89, and 13.6 ± 3.33 Bq/l of Jatlan, Dadyal, and Mirpur, respectively. These results revealed that mean concentrations of 222Rn were found within the maximum threshold limits (MCL, 11.1 Bq/l) of the United States Environmental Protection Agency (USEPA), however, that of Mirpur surpassed these limits. The concentrations of 222Rn in Mirpur District were evaluated for the annual effective doses (EwTotal). Results revealed that mean EwTotal values of the three studied sites in Mirpur District were found lower than the threshold limit (100 μSv/a), except 6% of sampling sites in the Mirpur. Higher EwTotal values than the WHO threshold limit in the Mirpur could pose threat to human health. The estimated lifetime cancer risk showed higher values along with the Mirpur of the study area. Therefore, this study recommends that water in the Mirpur area should be aerated or heated before consumption to avoid 222Rn impact on human health.