Determination of human health risk incorporating experimentally derived site-specific bioaccessibility of arsenic at an old abandoned smelter site.

This study was conducted to investigate the contribution of a site-specific bioavailability of arsenic (As) to human health risk at an old abandoned smelter site in Korea. The site was contaminated with As for over 60 years with the same source (As2O3 in flue gas), but concentration and in vitro bioaccessibility (IVBA) of As differed by operable units (OU), which consequently resulted in difference in estimated risk. Soil samples collected from six OUs showed that aqua regia-extractable As concentrations ranged from 9.8 to 52.8mg/kg (average 34.1mg/kg) at OUs 1-5, which had been used as rice paddy field and farmland, and a forest region OU 6 showed much higher As concentrations (14.4-169.8mg/kg, average 85.9mg/kg). IVBA of As, determined from the ratio of Solubility/Bioavailability Research Consortium (SBRC)-extractable As to aqua regia-extractable As had a wide range of values (90th percentile values of 28.2-65.8%). Carcinogenic risk calculated with total soil As concentration was the highest (1.4×10(-4)) at OU 6 and the risk at the other OUs ranged from 3.8×10(-5) to 5.7×10(-5). In contrast, when site-specific relative bioavailability (i.e., IVBA values) was incorporated, the estimated risk was reduced by 29.5-62.0% and the decrease was the highest at OUs 1 and 5 with the lowest IVBA of 28.2%. The results demonstrate that the chemical forms of As may be different although the source of contamination is similar, and site-specific bioavailability affected by the chemical forms is an important factor in determining human health risk.