Bioaccessibility of Cd and Pb in tailings from a zinc smelting in Brazil: implications for human health

• Published in: Environmental geochemistry and health Vol. 38; no. 5
• Main Authors: Ono, Fabio Benedito, Penido, Evanise Silva, Tappero, Ryan, Sparks, Donald, Guilherme, Luiz Roberto Guimaraes
• Format: Journal Article
• Language: English
• Published: United States Springer 22-10-2015
• Subjects: 60 APPLIED LIFE SCIENCES; anthropogenic impacts; environmental contamination; ENVIRONMENTAL SCIENCES; in vitro test; trace elements
• ISSN: 0269-4042; 1573-2983

Soils and wastes enriched with heavy metals may present significant ecological and human health risks. A considerable number of mining/smelting areas exist in Brazil, where high levels of metals have been found, as well as in their surrounding soils and sediments. However, studies of bioaccessibility of metals in soils/tailings from these areas are scarce, despite their potential informational contribution concerning exposure risks for residents near these areas. This study evaluated tailing samples collected from four sites of a smelting area aiming to: (i) evaluate the presence of metals of potential concern; (ii) investigate Cd and Pb bioaccessibility; and, (iii) determine the desorption kinetics of Cd and Pb. Five composite samples were collected from each site, at two depths, from a zinc smelting area located near Três Marias city - MG, Brazil. Availability of Cd and Pb was measured using a bioaccessibility test and a desorption experiment. High concentrations of total Cd and Pb and great variability were found in the tailings (up to 1743 mg Cd kg-1 and 8675 mg Pb kg-1), indicating the importance of adequate planning for their final disposal, in order to avoid contamination in the surrounding environment. Cadmium and Pb bioaccessibility percentages in the intestinal phase were less than 47 and 4%, respectively, which represents significant fractions not available for absorption in the intestinal tract. However, this material has to be monitored since its bioaccessibility may increase with eventual physicochemical changes, releasing Cd and Pb. Desorption kinetics experiments revealed that the Pb in the samples remained in less labile fractions whereas Cd was found in more labile fractions, which is in accordance with the bioaccessibility result.