U.S. EPA Contaminated Site Cleanup Information (CLU-IN)

U.S. Environmental Protection Agency
U.S. EPA Technology Innovation and Field Services Division

For more information on 1,4-Dioxane, please contact:

Linda Fiedler
Technology Assessment Branch

PH: (703) 603-7194 | Email: fiedler.linda@epa.gov


Chemistry and Behavior

1,4-Dioxane (CAS No. 123-91-1) is a volatile organic compound that has a moderate vapor pressure (38.0 mm Hg at 25º C), is completely miscible in water, and has a specific gravity of 1.033. When released to the air, it has a 6 to 10 hour half life and degrades to aldehydes and ketones. The very low log Kow (-.27) suggests that 1, 4-dioxane will be very mobile in soils. 1,4-Dioxane has a very low Henry's Constant (4.88 X 10-6) and is unlikely to form a vapor plume in the vadose zone above a dissolved phase plume, which means soil gas measurement techniques will not be useful for tracking it. Its low Henry's Constant also means that if it is released to a surface water body, it will remain in that body and not volatilize to a significant extent. At actual solvent release sites, 1,4-dioxane has been found to migrate considerably farther in ground water than solvents such as trichloroethane (TCA) or its breakdown products due to its complete miscibility. The compound is not expected to biodegrade in the environment.

1,4-Dioxane is flammable, and under certain conditions, such as improper storage with exposure to light and air, will form explosive peroxides that can be detonated by shock or heat.

Adapted from:

Handbook of Environmental Fate and Exposure Data for Organic Chemicals, Volume II Solvents
P. Howard. Lewis Publishers, 1991.

Adobe PDF LogoEnvironment, Safety, and Health Manual
UCRL-MA-133867, 1999.

Adobe PDF LogoSolvent Stabilizers: White Paper
T.K.G. Mohr, Santa Clara Valley Water District, 2001.
Contact: Tom Mohr, tommohr@scvwd.dst.ca.us

Evidence of 1,4-Dioxane Attenuation at Groundwater Sites Contaminated with Chlorinated Solvents and 1,4-Dioxane
Adamson, D., R. Anderson, S. Mahendra, and C. Newell.
Environmental Science & Technology 49(11):6510-6518(2015)

A comprehensive evaluation of California state (GeoTracker) and Air Force monitoring records provided significant evidence of 1,4-dioxane attenuation at field sites. Temporal changes in the site-wide maximum concentrations were used to estimate source attenuation rates at the GeoTracker sites (median length of monitoring period = 6.8 yr). Statistically significant positive attenuation rates were confirmed at 22 sites. At sites where dioxane and chlorinated solvents were present, the median value of all statistically significant dioxane source attenuation rates was lower than TCA but similar to 1,1-DCE and TCE. Dioxane attenuation rates were positively correlated with rates for 1,1-DCE and TCE but not TCA. The study sites gave little evidence that chlorinated solvent remedial efforts (e.g., chemical oxidation, enhanced bioremediation) affected dioxane attenuation. Attenuation rates based on well-specific records from the Air Force data set confirmed significant dioxane attenuation (131 of 441 wells) at a similar frequency and extent (median equivalent half-life = 48 months) as observed at the California sites. Linear discriminant analysis established a positive correlation between dioxane attenuation and increasing concentrations of dissolved oxygen, while the same analysis found a negative correlation with metals and CVOC concentrations. Results suggest that natural attenuation might be used to manage some but not necessarily all dioxane-affected sites.

Adobe PDF LogoOPPT Chemical Fact Sheets 1, 4-Dioxane Fact Sheet: Support Document (CAS No. 123-9-1)
U.S. EPA , Office of Pesticides and Toxic Substances.
EPA 749-F-95-010a, 13 pp, Feb. 1995.

Australian Government, Department of Health and Ageing, 112 pp, May 2003.