Oral bioavailability estimation of toxic and essential trace elements in PM10

Oral bioavailability of essential and toxic elements has been assessed in particulate matter samples (PM10) at several sites (industrial, urban and sub-urban sites) by using an in-vitro model that combines simulated gastric/intestinal fluids and physiologically based extraction conditions which simulate human digestive system. Metals concentrations in bioavailable fractions will allow to a real human health-risk assessment associated to toxic metals. High oral bioavailability percentages were found for metals such as Cu, Mn, Ni, Pb and Sb (oral bioavailability ratios in the range of 39.7-45.7%). Al and V are less bioavailables (oral bioavailability ratios in the range of 1.8-9.2%). The influence of chemical composition (major ions, carboxylic acids and black carbon (BC)) on bioavailability ratios was assessed. Fe, Ni, V and Zn bioavailability ratios was found to be affected by the K+, NH4+, acetate and BC contents of PM10; while a correlation was found between marine content (Cl- and Na+) of PM10 and Cu, Fe and Mn dialyzability ratios. Zn and Sr bioavailability ratios were correlated with crustal contribution of PM10. Principal Component Analysis (PCA) results also showed that Fe, Mn, Ni, Pb, Sb, Sr and V bioavailability are dependent on BC and NH4+ contents and Cu and Zn bioavailability are dependent on sea salt content of PM10. Predicted bioavailability for some metals after applying a quadratic surface model based on crustal, marine and anthropogenic content of PM10 could also be established. Toxicity prediction of target metals, by using hazard quotient/index values, suggested potential non-carcinogenic risk for Pb and Sb.