An in vitro gastrointestinal method to estimate bioavailable arsenic in contaminated soils and solid media

A method was developed to simulate the human gastrointestinal environment a nd to estimate bioavailability of arsenic in contaminated soil and solid me dia. In this in vitro gastrointestinal (IVG) method, arsenic is sequentiall y extracted from contaminated soil with simulated gastric and intestinal so lutions. A modified IVG-AB method, where iron hydroxide gel is used to simu late the absorption of arsenic, was also evaluated. Fifteen contaminated so ils collected from mining/smelter sites ranging from 401 to 17460 mg As kg( -1) were analyzed. In vitro results were compared with in vivo relative bio available arsenic (RBA) determined from dosing trials using immature swine which ranged from 2.7 to 42.8% RBA. Arsenic extracted by the IVG and IVG-AB methods was not statistically different than RBA arsenic measured by the i n vivo method. Arsenic extracted by the IVG stomach and intestinal phases w as linearly correlated (r = 0.83 and 0.82, respectively) with in vivo arsen ic (P < 0.01). Similarly, the IVG-AB method was linearly correlated (r = 0. 79) with in vivo bioavailable arsenic (P < 0.05). All IVG methods extracted similar amounts of arsenic and provided estimates of bioavailable As in co ntaminated media. The IVG method may aid in the design and cost-effectivene ss of remedial strategies of arsenic-contaminated sites.