Department of Environmental Health Sciences and YSPH Present: "Yale Virtual Symposium: 1,4-Dioxane: Occurrence, Toxicity and Population Risk"

1,4-Dioxane (1,4-DX), is a cyclic ether that is used as a solvent in the manufacture of other

chemicals and, for decades, was extensively used as a stabilizer for chlorinated solvents, most

notably 1,1,1,-trichloroethane. This had led to exten- sive environmental release and groundwater

contamination. 1,4-DX is also found as a contaminant in cosmetics, deter- gents, and shampoos. It

has been classified as a class 2B carcinogen by IARC and the US-EPA considers it to be a likely

human carcinogen. 1,4-DX is an emerging contaminant of growing concern based on its common

occurrence in drink- ing water supplies worldwide. Its high polarity and low biodegradability

hamper its retardation or removal from aquifer systems. 1,4-DX is carcinogenic in both mice and

rats. While the mechanism by which this occurs remains unknown, it appears to be distinct from

other well-known liver carcinogens. A lack of biomarkers of exposure to or the effects of this

compound hampers epidemiological studies. Given that liver cancer incidence rates have more than

tripled since 1980, there is an urgent need to evaluate emerging water contaminants that may be

contributing to this increase, such

as 1,4-DX.