Evaluation of water quality and human risk assessment due to heavy metals in groundwater around Muledane area of Vhembe District, Limpopo Province, South Africa.

Abstract

Groundwater is considered as good alternative to potable water because of its low turbidity and perceived low contamination. The study assessed the physio-chemical and heavy metals concentrations in eight randomly selected boreholes water at Muledane village in Limpopo Province of South Africa and the results were compared with South African National standard permissible limit. The impacts of heavy metals on human health was further determined by performing quantitative risk assessment through ingestion and dermal adsorption of heavy metals separately for adults and children in order to estimate the magnitude of heavy metals in the borehole samples. Parameters such as turbidity, nitrate, iron, manganese and chromium in some investigated boreholes did not comply with standard limits sets for domestic water use. Multivariate analyses using principal component analysis and hierarchical cluster analysis revealed natural and anthropogenic activities as sources of heavy metal contamination in the borehole water samples. The calculated non-carcinogenic effects using hazard quotient toxicity potential, cumulative hazard index and chronic daily intake of groundwater through ingestion and dermal adsorption pathways were less than a unity, which showed that consumption of the water could pose little or no significant health risk. However, maximum estimated values for an individual exceeded the risk limit of 10^-6 and 10^-4 with the highest estimated carcinogenic exposure risk (CR_ing) for Cr and Pb in the groundwater. This could pose potential health risk to both adults and children in the investigated area. Therefore, precaution needs to be taken to avoid potential CR_ing of people in Muledane area especially, children using the borehole water.