Abstract
As rural populations grow and rural poverty increases, consumption of fish from contaminated river systems will increase to supplement dietary protein requirements. The concentrations of metals in fish muscle tissue at two impoundments of the Olifants River (Flag Boshielo Dam and the Phalaborwa Barrage) were measured, and a human health risk assessment following Heath et al. (2004) conducted to investigate whether consumption of Schilbe intermedius from these impoundments posed a risk to human health. The results confirmed that metals are accumulating in the muscle tissue of S. intermedius. No patterns were observed in the ratios of the metals bio-accumulated at each impoundment. The human health risk assessment identified that all fish analysed exceeded the recommended levels for safe consumption for lead and chromium and about 50% exceeded the recommended level for antimony at Flag Boshielo Dam. Almost all fish analysed exceeded the recommended level for lead and more than 50% exceeded the recommended level for arsenic at the Phalaborwa Barrage. We conclude that weekly consumption of S. intermedius from these impoundments may pose an unacceptable risk to the health of rural communities.Keywords: risk assessment, human health, Schilbe intermedius, lead, chromium, antimony
Highlights
River systems have been adversely impacted by constant increases in domestic, agricultural, mining and industrial water abstraction and the release of contaminants such as metals and pesticides (Dudgeon et al, 2006; Strayer and Dudgeon, 2010; Vörösmarty et al, 2010)
The lead, antimony, arsenic and chromium concentrations in the muscle tissue were comparable to results from studies of metal accumulation in Oreochromis species (Al-Kahtani, 2009; Yilmaz, 2009; Jabeen and Chaudhry, 2010; Addo-Bediako et al, 2014)
A number of lead, tin and antimony ore bodies have been mined in the catchment
Summary
River systems have been adversely impacted by constant increases in domestic, agricultural, mining and industrial water abstraction and the release of contaminants such as metals and pesticides (Dudgeon et al, 2006; Strayer and Dudgeon, 2010; Vörösmarty et al, 2010). Most metals and metalloids (hereafter referred to as metals) occur naturally in the biogeochemical cycle, many are released into inland waters as industrial, mining, agricultural and domestic effluents, and may be deleterious to aquatic systems (Dallas and Day, 2004). Other metals occur naturally at very low concentrations in aquatic ecosystems and have no known physiological functions. These might be toxic even at low concentrations, but have become widely distributed as a result of human activities (e.g., Cd, Pb and Hg) (Davies and Day, 1998; Dallas and Day, 2004). PH, dissolved oxygen, temperature, salinity, interactions with other metal salts, and the presence of mineral and organic suspended solids all influence the bioavailability of metals (Chapman and Wang, 2000)
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