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Using paired soil and house dust samples in an in vitro assay to assess the post ingestion bioaccessibility of sorbed fipronil
Citation:
Starr, J., W. Li, S. Graham, K. Bradham, Dan Stout, A. Williams, AND J. Sylva. Using paired soil and house dust samples in an in vitro assay to assess the post ingestion bioaccessibility of sorbed fipronil. JOURNAL OF HAZARDOUS MATERIALS. Elsevier Science Ltd, New York, NY, 312:141-149, (2016).
Impact/Purpose:
The National Exposure Research Laboratory (NERL) Human Exposure and Atmospheric Sciences Division (HEASD) conducts research in support of EPA mission to protect human health and the environment. HEASD research program supports Goal 1 (Clean Air) and Goal 4 (Healthy People) of EPA strategic plan. More specifically, our division conducts research to characterize the movement of pollutants from the source to contact with humans. Our multidisciplinary research program produces Methods, Measurements, and Models to identify relationships between and characterize processes that link source emissions, environmental concentrations, human exposures, and target-tissue dose. The impact of these tools is improved regulatory programs and policies for EPA.
Description:
For children, ingestion of soils and house dusts can be an important exposure pathway for regulated organic compounds. Following ingestion, the extent to which compounds desorb and become bioaccessible is a critical determinant of systemic adsorption.We characterized the physicochemical properties of 37 soil and house dust pairs collected during a national survey of United States homes. For each sample, we measured the bioaccessibility of fipronil, a phenylpyrazole insecticide using an in vitro, three- compartment digestive system, then modeled the physicochemical predictors of fipronil bioaccessibility.The properties of the soils and dusts were not correlated and percent carbon was the only significant predictor of bioaccessibility for both soils (p < 0.001) and dusts (p < 0.001). The carbon content of the soils (3.1 ± 2.4%) was lower than that of the dusts (18.6 ± 6.9%)Due to the lower carbon content, soil sorbed fipronil was more bioaccessible than dust sorbed fipronil. However, the slope of the bioaccessibility carbon regression line was steeper for the soils than for the house dusts. This suggested that, for soils having carbon percentages greater than those in this study, fipronil bioaccessibility may be less than that of house dusts having equal carbon content.
