Lung bioaccessibility of As, Cu, Fe, Mn, Ni, Pb, and Zn in fine fraction (<20μm) from contaminated soils and mine tailings.

The present study aims (1) to characterize contaminated soils (n=6) and mine tailings samples (n=3) for As, Cu, Fe, Mn, Ni, Pb, and Zn content; and (2) to assess elemental lung bioaccessibility in fine fraction (d<20μm which might contribute to airborne particulate matter (PM) and thus be inhaled) by means of in vitro tests using Gamble's solution (GS) and an artificial lysosomal fluid (ALF). Elemental concentrations were high in the majority of samples, particularly for As (up to 2040mg·kg), Fe (up to 30.7%), Mn (up to 4360mg·kg), and Zn (up to 4060mg·kg); and elemental concentrations (As, Cu, and Ni) in the sieved fraction (d<20μm) obtained from contaminated soils were significantly higher than in the bulk fraction (<160μm). In vitro tests with ALF yielded much higher bioaccessibility than tests with GS, and the use of ALF in addition to GS is recommended to assess lung bioaccessibility. Bioaccessibility in ALF was high for all elements after 2weeks of testing both in terms of concentration (e.g. up to 1730mg·kg for As) and percentages (e.g. up to 81% for Pb). The elemental solubilization rate generally declined rapidly and continuously with time. Similarly, bioaccessibility increased rapidly and tended to reach a plateau with time for most samples and metals. However, it is not possible to recommend a general testing duration as the solubilization behavior was highly element and sample-specific.