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Population Based Exposure Assessment of Bioaccessible Arsenic in Carrots
Citation:
Yathavakilla, S. K., A. R. Young, S. E. Lenhof, M. Mantha, C. GALLAWA, P. A. CREED, J. XUE, AND JOHN T. CREED. Population Based Exposure Assessment of Bioaccessible Arsenic in Carrots. Presented at International Symposium on Mettalomics, Covington, KY, June 07 - 13, 2009.
Impact/Purpose:
Develop analytical approaches to quantify reactive intermediates within the metabolic pathway that biotransforms inorganic arsenic to DMA(V). The ability to quantify these species will enhance the mode of action (within NHEERL) and the bioavailability / bioaccessibility research (within NERL).
Description:
The two predominant arsenic exposure routes are food and water. Estimating the risk from dietary exposures is complicated, owing to the chemical form dependent toxicity of arsenic and the diversity of arsenicals present in dietary matrices. Two aspects of assessing dietary exposure risk, which are often overlooked in speciation analysis, are producing a bioaccessibility estimate and the need to collect samples which support a population based exposure assessment. In an attempt to address these shortcomings, the authors have applied an enzymatic extraction to carrots which were collected from various geographical locations based on harvest demographics. The extracts were speciated by IC-ICP-MS utilizing collision cell technology to address the high chloride concentrations characteristic of in-vitro assays designed to mimic the gastrointestinal tract. The distribution of the inorganic arsenic concentration in carrots was then combined with the distribution associated with carrot consumption in the US using a probabilistic based model. The model randomly selects an arsenic concentration and consumption rate from the distributions and through an iterative process generates a population based exposure profile for arsenic in carrots. This approach to population based exposure assessment is especially applicable to arsenic because over 90% of the exposure can be attributed to 4-5 commonly consumed foods. This limited number of foods produces a relatively robust estimate without having to independently estimate the contribution of all other foods to the cumulative exposure. This presentation will discuss the limitations associated with the IC-ICP-MS approach and outline the application of the model to this type of exposure assessment.