Health risk assessment of dust samples (indoor and outdoor) collected from houses around a mining area in Brits, South Africa

Mining activities are major contributors to metallic dust found in households, both indoor and outdoor. The present study determines the concentrations of trace metals in indoor and outdoor dust samples collected from houses around a mining area with a view to establishing their impact on human health. Eighty dust samples were collected from households near a mining area and were analysed for trace metal concentrations using inductively coupled plasma mass spectrometry (ICP – MS). The metal concentrations were in the order Fe > Mg > Mn > Cr > Zn > As > Ni > Hg > Cd > Cu for indoor and Mg > Fe > Cu > Cr > As > Zn > Hg > Cd > Ni > Mn for outdoor dust. The concentration of metals Hg, Cr and As were higher than the permissible limit of 0.9 µg/g, 6.5 µg/g and 5.8 µg/g, respectively set by South Africa and that of Cd exceeded the limit of 3.0 µg/g set by World health organisation (WHO) for human exposure. The result showed that there was a correlation in the concentration, between Fe and Mn, Fe and Cr, Fe and As, Fe and Ni, as well as with Fe and Cd from indoor dust samples. Correlation was also observed between Mg and Mn, Mg and Cr, Mg and Zn, Mg and As, Mg and Ni (p < 0.01) and Fe and Cd from outdoor dust samples. Correlation was also established between outdoor Mg and As, with indoor Hg in the dust samples. The pollution assessments indicated that households were within the range of 0 < Igeo < 1, which is classified as unpolluted to moderately polluted. The results also showed that the pollution was due to anthropogenic sources. It is concluded that exposure to mining activity may pose a threat to human health, especially with regard to trace metal concentrations that have exceeded the permissible limit for human exposure. The health risk assessment for humans indicated that there might be a future concern for human health over time.