HEALTH RISK ASSESSMENT OF AS, NI AND PB FROM A SCHOOL PLAYGROUND SOIL NEAR AN OLD GOLDMINE TAILINGS DUMP IN THE MURCHISON AREA (LIMPOPO PROVINCE), SOUTH AFRICA

Gold mining remains one of the major sources of metal(loid) emissions into the environment. Areas polluted by the persistent presence of metal(loid)s induce health problems, especially when recreational activities promote human exposure to the pollutants. This study presents preliminary findings on potential health risk for children exposed to As, Ni and Pb from goldmine tailings contaminated soils at a school playground in Murchison. Pseudo- total heavy metal(loid) concentrations of six composite soil samples (representative of the total expanse of the playground) were used to calculate Chemical Daily Intake (CDI), Hazard Quotient (HQ), Chronic Hazard Index (CHI) and Carcinogenic Risk (CR) levels through ingestion, inhalation and dermal absorption pathways. Health risks were assessed based on the United States Environmental Protection Agency (USEPA) guidelines, whereby HQ > 1, CHI > 1 and CR > 1 x 10^-4; CR > 5 x 10^-6 represent elevated risks. Heavy metal(loid) concentrations were distributed as follows; As (320 – 1336 mg/kg), Ni (582 – 1776 mg/kg) and Pb (36 – 348 mg/kg), with mean values of 777.7, 1066.5 and 149.8 mg/kg respectively. The CDI values based on all three pathways were highest for Ni and lowest for Pb. Exposure to non-carcinogenic risks via ingestion and dermal absorption was evident (HQ > 1) while no risks were observed for the inhalation pathway. Total CHI was in the order Pb > As> Ni with corresponding values of 55.27, 34.41 and 18.23 respectively. Compared against USEPA threshold values, the children were found to be significantly exposed to carcinogenic risks from As (4 x 10^-2), Ni (1 x 10^-2) and Pb (2 x 10^-4) exposure. In addition, the negative implications of Pb poisoning on optimal neurological and cognitive development of the children is inferred. Based on these findings, a number of measures have been advanced to mitigate further exposure to potential health risks.