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Modeling the post-ingestion bioaccessibility of organic compounds sorbed to soils and house dusts (2018 SETAC North America Meeting)
Citation:
Starr, J., H. Shen, W. Li, AND S. Graham. Modeling the post-ingestion bioaccessibility of organic compounds sorbed to soils and house dusts (2018 SETAC North America Meeting). 2018 SETAC North America Meeting, Sacramento, CA, November 04 - 08, 2018.
Impact/Purpose:
Ingestion of soils and house dusts with sorbed toxicants is an important pathway for children’s exposure to many regulated organic chemicals. Therefore, it is important to understand the extent to which soil/dust sorbed toxicants mobilize (become bioaccessible) in the digestive tract. Results for an in vitro, three-compartment system to model the bioaccessibility of the insecticide fipronil and 18 polychlorinated biphenyls (PCBs) from 37 soil and 37 house dust samples will be reported.
Description:
Ingestion of soils and house dusts with sorbed toxicants is an important pathway for children’s exposure to many regulated organic chemicals. Therefore, it is important to understand the extent to which soil/dust sorbed toxicants mobilize (become bioaccessible) in the digestive tract. We used an in vitro, three-compartment system to model the bioaccessibility of the insecticide fipronil and 18 polychlorinated biphenyls (PCBs) from 37 soil and 37 house dust samples. For each sample. freely dissolved and total concentrations of fipronil and PCBs in the digestive fluid were measured and compared to concentrations remaining in the soil/dust sediments to calculate percent free (BAfrc) and total (BAtotc) bioaccessible fractions. Physicochemical soil and dust properties, and log octanol-water partition coefficients (log Kow) of fipronil and PCBs were used to generate bioaccessibility models. In soil, mean BAtotc were 89 ± 10% (fipronil) and 65 ± 16 % (PCBs). In house dust, mean BAtotc were 58 ± 17% (fipronil) and 36 ± 14 % (PCBs). Most of the bioaccessible fipronil was freely dissolved whereas all of the measureable PCBs were bound to organic constituents or trapped in micelles. The significant bioaccessibility predictors were: Carbon (fipronil soil, r2 = 0.62; fipronil dust, r2 = 0.30; PCBs soil r2 = 0.65) and carbon/clay (PCBs dust, r2 = 0.56). Combined fipronil / PCB models of BAtotc retained only carbon and log Kow for both soil (r2 = 0.78) and dust (r2 = 0.65). These results indicate that bioaccessibility can be modeled using properties of chemicals, soils, and house dusts.
