Assessment of radionuclide levels in drinking water from communities in the West Rand region of the Gauteng Province, South Africa

Abstract

This research contributes to the protection of members of the West Rand communities from radiological harm emanating from drinking water through the establishment of radionuclide levels in drinking water and the associated health risks of ingestion. The long-standing history of gold mining and processing in the Witwatersrand Basin has resulted in an exponential increase in the amount of radionuclides released into the environment, including the water system. As such, it is paramount to ensure the public and environment are protected from any pollution related to gold mining. The aim of this study was to assess and quantify radionuclide levels in drinking water (groundwater and municipal water) and the health risks associated with the ingestion of the water in residential communities of the West Rand region. Activity concentrations of 238U, 235U, 234U, 232Th, 230Th, 228Th, 228Ra, 226Ra and 224Ra in 22 drinking water samples were determined using alpha spectrometry, which were subsequently used to evaluate the radiological risks related to the ingestion of 238U in the water. The results indicate that groundwaters largely contain elevated activity concentrations of most radionuclides owing to the untreated nature of the water as opposed to the municipal-supplied water. Similarly, annual effective dose and cancer morbidity and mortality risk estimates were found to be higher in groundwater. Annual effective dose estimates in all samples were well below the prescribed limit of 0.1mSv/y, with a range of 0.0237–0.3106 mSv/yr. Cancer morbidity and mortality risk estimates were higher in females than males in all samples due to the higher life expectancy of females. Nevertheless, all morbidity and mortality risk estimates were significantly lower than the prescribed radiological risk limit of 0.001. All sampled drinking water was found to be radiologically safe for human consumption. Based on the findings of this study, continuous monitoring of the drinking water with an emphasis on groundwater should be implemented to ensure that radionuclide levels and associated health risks remain below local and international prescribed regulatory limits. Keywords: Gold mining, drinking water, radionuclides, annual effective dose, cancer risk