Assessment of Non-Occupational 1,4-Dioxane Exposure Pathways from Drinking Water and Product Use

1,4-Dioxane is a persistent and mobile organic chemical that has beenfound by the United States Environmental Protection Agency (USEPA) to be anunreasonable risk to human health in some occupational contexts. 1,4-Dioxane isreleased into the environment as industrial waste and occurs in some personal-careproducts as an unintended byproduct. However, limited exposure assessments havebeen conducted outside of an occupational context. In this study, the USEPAsimulation modeling tool, Stochastic Human Exposure and Dose Simulator-HighThroughput (SHEDS-HT), was adapted to estimate the exposure and chemical massreleased down the drain (DTD) from drinking water consumption and product use.1,4-Dioxane concentrations measured in drinking water and consumer products wereused by SHEDS-HT to evaluate and compare the contributions of these sources toexposure and mass released DTD. Modeling results showed that compared to peoplewhose daily per capita exposure came from only products (2.29x10-7to 2.92x10-7mg/kg/day), people exposed to both contaminated water and product use had higherper capita median exposures (1.90x10-6to 4.27x10-6mg/kg/day), with exposure mass primarily attributable to waterconsumption (75-91%). Last, we demonstrate through simulation that while a potential regulatory action could broadly reduceDTD release, the proportional reduction in exposure would be most significant for people with no or low water contamination.

Automated summary

This study estimated the exposure and mass released of 1,4-dioxane from drinking water consumption and product use using a simulation modeling tool. The results showed that people exposed to both contaminated water and product use had higher exposures, primarily attributable to water consumption.