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A scientific workflow to estimate non-occupational 1,4-dioxane exposure pathways from drinking water and product use
Citation:
Dawson, D., H. Fisher, A. Noble, Q. Meng, A. Doherty, Y. Sakano, Dan Vallero, R. Tornero-Velez, AND E. Hubal. A scientific workflow to estimate non-occupational 1,4-dioxane exposure pathways from drinking water and product use. Society of Toxicology, San Diego, CA, March 27 - 31, 2022. https://doi.org/10.23645/epacomptox.19346774
Impact/Purpose:
N/A
Description:
1,4-Dioxane is a persistent and mobile organic chemical that has been found to be an unreasonable risk to human health in some occupational contexts. It is used in a variety of industrial applications and occurs as an unintended byproduct of ethoxylated surfactants in some personal-care products such as detergents and soaps. Both sources may contribute to direct human exposure, wastewater contamination, and contamination of downstream drinking water. However, there have been limited exposure assessments of 1,4-dioxane outside of an occupational context. We designed and executed a workflow using USEPA’s simulation modeling tool, SHEDS-HT, to estimate non-occupational exposure and the chemical mass released down the drain from using drinking water and consumer products contaminated with 1,4-dioxane. This workflow used a factorial approach to compare how factors associated with drinking water (geographic scale (US or US State of California) and source (groundwater, surface water, or mixed water)) and prevalence of 1,4-dioxane in consumer products influenced exposure and mass released down the drain. To evaluate the reliability of model predictions, we projected estimates of mass released down the drain to wastewater effluent concentrations, and compared them to empirical 1,4 dioxane data collected at wastewater treatment plants. Finally, we simulated a regulatory scenario in which a 1 mg/l threshold is imposed on 1,4-dioxane concentrations in consumer products. Factorial model simulations showed that the population distributions of estimated exposure and mass released down the drain were strongly influenced by the probabilistic methods underlying SHEDS-HT, whereas the considered factors had relatively minor influences. However, for the subset of people with contaminated water, exposure was primarily driven by drinking water consumption. In contrast, mass released down-the-drain was driven by consumer product use, regardless of the influence of contaminated water use. The credibility of these results was bolstered by a reasonable correspondence between 1,4-dioxane monitoring data collected at wastewater plants and model predictions of mass released down-the-drain. Lastly, while the simulated regulatory action reduced both exposure and mass released down the drain, the effect on exposure was influenced by the presence and extent of water contamination. The workflow developed for this assessment can readily be adapted to additional exposure scenarios for 1,4-dioxane and may serve as a starting template for modeling exposure to other persistent and mobile organic chemicals.
URLs/Downloads:
DOI: A scientific workflow to estimate non-occupational 1,4-dioxane exposure pathways from drinking water and product use
DAWSON_SOT_2022_POSTER_4.PDF (PDF, NA pp, 735.62 KB, about PDF)