1,4-Dioxane

1,4-Dioxane is an organic compound that was widely used as a solvent and stabilizer in industrial applications during the late 20th century.It is a clear liquid that migrates easily in groundwater and tends not to biodegrade. The odd name refers to its chemical structure, a cyclic structure with two oxygen atoms occupying the first and fourth positions as counted around the six atoms making up the molecule’s “ring.” 1,4-Dioxane is often just called “dioxane” because the other isomers (1,2 and 1,3) are rarely encountered. Dioxane should not be confused with dioxins, a different group of chemicals.

Public domain image from https://en.wikipedia.org/wiki/1,4-Dioxane. Red = oxygen; black = carbon; grey = hydrogen.

1,4-Dioxane has become an environmental problem in Acton in the 21st century because it has leached out of the W.R. Grace and Nuclear Metals, Inc. Superfund sites and travelled through the groundwater, and is encroaching on some of Acton’s town water wells. 1,4-Dioxane is an emerging pollutant. It has only recently become possible to measure its concentration at low levels, and toxicology research on its health impacts is at an early stage.

The Massachusetts Department of Environmental Protection (MassDEP) Office of Research and Standards has established a drinking water guideline for 1,4-Dioxane of 0.3 micrograms per liter, sometimes reported as 0.3 parts per billion (ppb.) This value is based on laboratory studies on rodents, in which adverse effects were found in livers and kidneys. A “guideline” is not as strong as a “standard,” and is not legally enforceable. However, the Acton Water District has been carefully keeping the level of 1,4-Dioxane in Acton’s drinking water below this threshold, by frequent monitoring and blending water from affected wells with water from unaffected wells to reduce concentrations.

Green Acton coverage of 1,4-Dioxane (most recent at top)
Links outside of Green Acton