Assessing health risk associated with uranium in Rietspruit water, far West Rand goldfield, South Africa

Abstract

Uranium, U, as a radiological and chemically toxic element has detrimental impacts on human health when ingested at elevated concentration in water. Effluents from an underground gold mine located in the head water region of the Rietspruit contaminated the stream with waterborne uranium. The Rietspruit is a tributary of the Vaal River and subsequently flows through residential and agricultural land. Water samples from the stream were collected and analysed using inductively coupled plasma mass spectrometry to determine the concentrations of dissolved U. The maximum concentration of U recorded was 781.9 µg/L at the mine from where it decreases with growing distance from the mine. Results from calculations showed that the maximum annual effective dose at the mine was above the regulatory limit for public exposure for all age groups. The radiological risk associated with consumption of untreated water from the Rietspruit is lower than the chemical risk. The chemical risk ranges from 0 to 37.2 while the highest life-time cancer risk was 1.7 E-03 for morbidity cancer risk and 1.1 E-03 for mortality cancer risk. The chemical risk analysis showed that within 24 km of downstream of the mine, stream users are exposed to toxic U levels. Therefore, adequate interventions by relevant government agencies are required.