環境および分析毒性学

An Integrated Health Risk Evaluation of Toxic Heavy Metals in Water from Richards Bay, South Africa

Abstract

Felix B Masok, Paulus L Masiteng, Risimati D Mavunda and Peane P Maleka

Heavy metals may affect human health in diverse ways ranging from cancer, reduced growth and development of nervous system damage, organ damage and in extreme cases, death. This study assessed the hazards of heavy metal based on target hazard quotient (THQ), derived from concentrations of heavy metals in water. Eighty-eight (88) water samples were collected from five sources and analyzed for lead (Pb), chromium (Cr), cadmium (Cd), iron (Fe), manganese (Mn), copper (Cu) and zinc (Zn) using inductively couple plasma and mass spectrometer (ICP-MS). Their health risks were assessed for oral ingestion and dermal absorption. The non-carcinogenic effects of these metals due to ingestion were found to be in a decreasing order: stream water>effluent water>Indian Ocean>Mzingazi river>Esikhawini tap water. Whereas via dermal absorption, the effects decrease in the order: effluent water>stream water>Mzingazi river>Esikhawini tap water>Indian Ocean. Additionally, carcinogenic risks were found to range from 1.03×10-10-6.56×10-7 in effluent water, 1.14×10-8-2.22×10-7 in stream, 55.15×10-11-2.61×10-7 in Indian ocean, 4.07×10-9-1.41×10-7 in Esikhawini tap water and 5.15×10-11-2.71×10-7 in Mzingazi river. The Hazard indexes of these selected metals in effluent water, river, Indian ocean and Esikhawini tap water were found to be less than a unity, indicating an unlikely health risk to the population using water from these sources.