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An In Vitro Assessment of Bioaccessibility of Arsenicals in Rice and the Use of this Estimate within a Probabilistic Exposure Model
Citation:
Trenary, H., P. A. CREED, A. Young, M. Mantha, C. A. SCHWEGEL, J. XUE, M. J. KOHAN, K. HERBIN-DAVIS, D. J. THOMAS, AND JOHN T. CREED. An In Vitro Assessment of Bioaccessibility of Arsenicals in Rice and the Use of this Estimate within a Probabilistic Exposure Model . Journal of Exposure Science and Environmental Epidemiology . Nature Publishing Group, London, Uk, 22(4):369-375, (2012).
Impact/Purpose:
Develop analytical approaches to quantify reactive intermediates within the metabolic pathway of arsenic to enhance the mode of action / metabolism research (within NHEERL) and to develop the bioavailability / bioaccessibility research (within NERL). By developing species specific bioaccessibility estimates of inorganic arsenic in demographically harvested target foods it becomes possible to estimate population based exposures using probabilistic models like SHEDS.
Description:
In this study, an in vitro synthetic gastrointestinal extraction protocol was used to estimate bioaccessibility of different arsenicals present in seventeen rice samples of various grain types that were collected across the US. The across matrix average for total arsenic was 209 ng/g ± 153 (x ± 2Σ). The bioaccessibility estimate produced an across matrix average of 61 % ± 19 ( x± 2ç). The across matrix average concentrations of iAs and DMA were 81 ng/g ± 67.7 and 41 ng/g ± 58.1 (x ± 2ç), respectively. This distribution of iAs concentrations in rice was combined with the distribution of consumption patterns (from WWEIA) in a SHEDS model to estimate population-based exposures. The mean consumption rate for the population as a whole was 15.7 g/day resulting in a 0.98 µg iAs/day exposure. The mean consumption rate for children 1-2 years old was 7 g/day resulting in a 0.48 µg iAs/day exposure. Presystemic biotransformation of DMA in rice was examined using an in vitro assay containing the anaerobic microbiota of mouse cecum. This assay indicated that DMA extracted from the rice was converted to DMTA, although a second oxygen–sulfur exchange to produce DMDTA was not observed.