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 (CRing) 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 CRing of people in Muledane area especially, children using the borehole water.
Highlights
Sustainable access to potable water have been achieved in different developed countries of the world, but this is not true for many developing countries
Only 12.5% boreholes have ideal water quality in terms of NO3− and Mn concentration with 25% found to be in the marginal water quality class, while 75% percent fell in the unacceptable water quality class
This study reveals that 87.5% borehole water have high concentration of NO3; Fe and Mn among the selected anions and heavy metals
Summary
Sustainable access to potable water have been achieved in different developed countries of the world, but this is not true for many developing countries. In Africa, access to potable water has been achieved in a few cities but not in the entire region. This problem is more pronounced in rural areas, some of which does not have water supply. Groundwater is often considered as the best of these alternatives, owing to natural protection from pollution when compared to surface and perceived natural filtration as water flows down during rainy period. Groundwater as one of the natural resources is of fundamental importance to human life, because of its perceived good microbiological quality in the natural state and as a result, it is often the preferred source of drinking water supply as treatment is limited to disinfection. Some factors that influence the quality of groundwater include the geology of the aquifer, climate and anthropogenic activities [5,6,7,8]
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