Occurrence and hazard assessment of natural radioactivity in drinking water in South Lebanon

This study is intended to assess the natural radioactivity in the drinking water in the southern region of Lebanon and to determine its suitability for human consumption. In this context, activity concentrations for gross alpha, gross beta, ²³⁸U, ²³⁴U, and radon from selected drinking water sources, wells, and springs and the corresponding tap water, in the area under investigation, were determined during both the wet and the dry seasons. The maximum recorded activities of gross alpha, gross beta, and radon measured using liquid scintillation counter were found to be 374.6 ± 11.5 mBq L^-1 for gross alpha, 418 ± 12 mBq L^-1 for gross beta, and 42,900 ± 370 mBq L^-1 for radon. Whereas, alpha spectroscopy analysis for uranium content showed maximum activities of 53.7 ± 2.1 mBq L^-1 for ²³⁸U and 55.9 ± 2.3 mBq L^-1 for ²³⁴U. Significant seasonal activity variation between wet and dry season was noticed only in gross alpha concentrations. In addition, significant variation between sources and tap water was recorded only in radon concentrations. Whereas, no significant variation was noted in radioactivity concentrations in waters from springs and those from wells. In contrast to all sampled locations, the annual effective dose of only one sampled well (Aitaroun) exceeded the WHO individual dose criterion (IDC) level of 100 µSv year^-1 and recorded an annual effective dose of 170 µSv year^-1, 103 µSv year^-1, and 127 µSv year^-1 for infants, children, and adults, respectively.