BIOACCESSIBILITY OF WIND TRANSPORTABLE METAL(LOID)S FROM MINE WASTES IN THE WESTERN UNITED STATES

Recent studies have underscored concerns regarding health risks associated with wind transport of toxic metal(loid)s sourced from abandoned mine tailings. Use of mine wastes as road fill, as is a common practice in Fairbanks, Alaska, can further exacerbate metal(loid) translocation to populated areas and facilitate human exposure. Indeed, anthropogenic enrichment of toxic metal(loid)s (e.g., As, Cd, Cu, Pb, Zn, and Ni) along roadways has been reported in urban and rural areas. In order to pose a health risk, metal(oid)s from the tailings must enter the body, either by inhalation or ingestion, then solubilize under conditions present in the lung or GI tract. In this study, we report the total metal(loid) content in geomedia as well as the physiologically-soluble fraction from mine tailings from across the Western US and road dust from the Fairbanks area in Alaska.

Surficial (0-2 cm) samples were collected from mine tailings in the southwestern US and road dusts were collected using passive samplers and artificial disturbance in Fairbanks, AK. Samples were subjected to total elemental analysis and size fractioned by dry sieving to determine the fractions of particles that are small enough for ingestion, wind transport, and inhalation. The smallest and most mobile fraction (< 38 µm) represented 2 to 14% of the bulk sample by mass. Appropriately size fractionated samples were subjected to physiologically based extraction tests (PBETs) simulating interaction of geomedia with lung and stomach fluids prior to supernatant analysis by ICP-MS. These results lend insight into evaluating the health risk associated with wind transported metal(loid)s from mining activities.