Importance of the oral arsenic bioaccessibility factor for characterising the risk associated with soil ingestion in a mining-influenced zone

Arsenic is a carcinogenic metalloid and the risks of accidental ingestion should therefore be borne in mind when assessing areas with high levels of this element. In this work, the concentrations of bioaccessible As in mining-influenced soils, in SE Spain are determined. The risk posed by the accidental ingestion is studied in two soil fractions (<2 mm and <250 μm), taking into consideration the possible uses of the soils (residential/agricultural) and possible receptors (adults and/or children). The properties and mineralogical composition of 26 soil samples are analysed. The results showed that the use of a conservative approach to calculate the Chemical Daily Intake (CDI) based on the total concentrations of arsenic, may overestimate the risk existing in the zone, leading to problems in the management of contaminated soils. The paper emphasises the importance of considering the amount of bioaccessible As in the <250 μm fraction before permitting land near temporary watercourses to be used for residential purposes, as beaches or for agriculture.

► In the soils studied, As is bound to the fine particles such as iron oxides. ► DCI is higher when the bioaccesibility factor is not taken into account. ► The use of total As in soil for calculated risk might cause unnecessary social alarm.