In vitro bioaccessibility method for prediction of relative bioavailability of arsenic in contaminated soils

Accurate assessment of human health risks from exposure to arsenic (As) contaminated soils depends on estimating its bioavailability. Bioavailability methods are needed to provide inexpensive, accurate, and reliable data that... [ view full abstract ]

Accurate assessment of human health risks from exposure to arsenic (As) contaminated soils depends on estimating its bioavailability. Bioavailability methods are needed to provide inexpensive, accurate, and reliable data that can be applied to cleanups of arsenic-contaminated sites. We evaluated 5 commonly used in vitro bioaccessibility (IVBA) methods to determine the bioaccessibility of As in 40 contaminated soils from the United States and Australia. A wide variety of soils were used in this study, including reference materials, railway corridors, cattle tick dip, gossan sites, and residential soils affected by mining or smelting. Arsenic bioaccessibility was highly correlated with the in vivo mouse assay results (R2=0.92). Research was also conducted to evaluate the predictive capabilities of an IVBA assay for As RBA in mice and to develop a more robust model across multiple soil types, arsenic contaminant sources, and arsenic concentrations. We validated the predictive capability of this model using an independent set of arsenic contaminated soils. Validation of model performance using data independent to those used to construct the model is imperative for IVBA data to be used routinely for incorporation into human health risk assessments. Arsenic speciation in soils was examined using the Materials Research Collaborative Access Team's (MRCAT) beamline, Argonne National Laboratory (ANL). AsV species were the dominant arsenic forms in most test soils while other soils had appreciable levels of AsIII sulfide or ore species. The in vivo-in vitro correlation and independent data validation presented provide critical verification necessary for regulatory acceptance in human health risk assessment.