Arsenic chemical form by XANES, bioaccessibility measurement and prediction in environmental samples for human health risk assessment purposes

Abstract

The Physiologically Based Extract Test (PBET) was used to measure in-vitro arsenic bioaccessibility in mine wastes from mine sites in Northern Australia, and X-ray Absorption Near Edge Spectroscopy (XANES) was used to obtain arsenic speciation data directly in the solid phase of mine waste samples. Because Arsenate (As(V)), the oxidized form of arsenic, is more likely to be found in mine waste materials, the XANES results from fitting with As model compounds support the finding that measured bioaccessibility was in good agreement with the predicted values and show a strong association with the presence of ferric arsenate and As sulfides. The results indicate that soil intake adjusted for bioaccessibility is less than the default and conservative assumption of 100% bioavailability often employed for the risk assessment calculation for health risk estimate of local residents exposed to the mine waste.