Toxic risk assessment and environmental contamination of heavy metals around abandoned metal mine sites in Korea

In order to investigate the levels of heavy metal contamination and to assess the risk of the adverse health effects on human exposure to toxic heavy metals influenced by past mining activities, environmental geochemical surveys were undertaken around abandoned metal mine sites (Okdong Cu-Pb-Zn, Dokok Au-Ag-Cu and Hwacheon Au-Ag-Pb-Zn mines). High concentrations of heavy metals were found in tailings from the Okdong (72 As mg/kg, 53.6 Cd mg/kg, 910 Cu mg/kg, 1,590 Pb mg/kg, 5,720 Zn mg/kg), the Dokok (254 As mg/kg, 98.2 Cd mg/kg, 2,550 Cu mg/kg, 4,200 Pb mg/kg, 18,020 Zn mg/kg) and the Hwacheon (72 As mg/kg, 12.4 Cd mg/kg, 580 Pb mg/kg, 1,300 Zn mg/kg) mines. Elevated levels of As, Cd, Pb and Zn were also found in agricultural soils from these mine areas. Human risk effects are classified into a cancer effect and a toxic (noncancer) effect. The hazard index representing a toxic risk for As was higher value than 1.0 in the Okdong and the Hwacheon mine sites, as was that for Cd in the Okdong and Dokok mine sites. Therefore, toxic risks for As and Cd exist via exposure (ingestion) to the contaminated soil, groundwater and rice grains in these mine areas. The cancer risk for As by the consumption of groundwater used as drinking water from the Okdong and the Hwacheon mine areas was 7E-4 and 1E-4, respectively. These risk levels exceed the acceptable risk (1 in 100,000) for regulatory purposes.