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Technology Assessment Branch
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- Policy and Guidance
- Chemistry and Behavior
- Environmental Occurrence
- Detection and Site Characterization
- Treatment Technologies
- Conferences and Seminars
- Additional Resources
1,4-Dioxane (C4H8O2, CAS No. 123-91-1) also can be identified as dioxane, dioxan, p-dioxane, diethylene dioxide, diethylene oxide, diethylene ether, or glycol ethylene ether.
A colorless, flammable liquid with a faint, pleasant odor, the synthetic industrial chemical is used as a solvent for extracting animal and vegetable oils and in the formulation of inks, coatings, and adhesives. In the laboratory, 1,4-dioxane is useful as a cryoscopic solvent for molecular mass determinations and as a stable reaction medium for diverse reactions. 1,4-Dioxane is used primarily as a solvent in paints, varnishes, lacquers, cosmetics, deodorants, cleaning and detergent preparations, and in scintillating fluids. Literature searches also indicated the potential for use as a solvent in the processing of crude petroleum, petroleum refining, petrochemicals, pulp and paper, explosives, commercial printing, electroplating/polishing, pesticide and agricultural manufacture, dyes, fiber manufacture, pharmaceuticals, adhesives, semiconductors, electronic components, photographic equipment, magnetic recording media, polymers, plastics, rubber manufacture, and organic and inorganic chemical manufacture. 1,4-Dioxane often has been used with chlorinated solvents, particularly 1,1,1-trichloroethane (TCA), as a stabilizer and corrosion inhibitor.
When 1,4-dioxane is used as a solvent stabilizer, the solvent itself is regulated as hazardous waste. When applied as an additive, 1,4-dioxane is not used for its solvent properties and does not meet the regulatory definition of solvent. 1,4-Dioxane generally is listed with a group of pollutants in state and federal guidance for air pollution control and release reporting and in water pollutant control and National Pollutant Discharge Elimination System (NPDES) permitting.
1,4-Dioxane is highly flammable and potentially explosive if not stored properly. The chemical is a cyclic ether that is highly miscible in water; in fact, it mixes with water so readily that it can be found in ground-water plumes far in advance of any solvents with which it might have entered the subsurface originally. It also migrates rapidly in soil. 1,4-Dioxane contamination often can be found in association with releases of chlorinated solvents.
EPA has listed the compound as a probable human carcinogen based on the results of animal studies, but little information is available on the long-term effects of 1,4-dioxane on human health.
The compound does not respond to air stripping or granular activated carbon treatment, nor does it biodegrade in the subsurface other than very slowly. Researchers are developing new treatment technologies for 1,4-dioxane, but advanced oxidation processes involving hydrogen peroxide and ultraviolet light or ozone have been applied successfully, and phytoremediation shows promise for its removal at depths accessible to plant roots. For currently available test methods for 1,4-Dioxane see Detection and Site Characterization.
Memorandum: 1,4-Dioxane Action Level
G. Alexeeff, California Office of Environmental Health Hazard Assessment, 1998.
U.S. EPA, Office of Solid Waste, 1996.
1, 4-Dioxane Fact Sheet: Support Document (CAS No. 123-9-1)
U.S. EPA, Office of Pollution Prevention and Toxics (OPPT) Chemical Fact Sheet.
EPA 749-F-95-010a, 13 pp, 1995.
1,4-Dioxane: the Emerging Contaminant That Keeps on Emerging
Mohr, T. Groundwater Resources Association of California, 62 slides, 2013
This presentation by recognized expert Thomas Mohr provides background information on the use and occurrence of 1,4-dioxane; the chemical properties that govern its fate and transport; and challenges and solutions to its analysis in the laboratory. Field examples are provided to illustrate plume dynamics and 1,4-dioxane treatment challenges and costs. The final section discusses common misconceptions about the compound. [NOTE: The presentation begins on slide 9.]
1,4-Dioxane: Priority Existing Chemical No. 7
National Industrial Chemicals Notification and Assessment Scheme.
AusInfo, Commonwealth of Australia, ISBN: 0-642-47104-5, 125 pp, 1998.
Emerging Contaminant - 1,4 Dioxane
U.S. EPA, Federal Facilities Restoration and Reuse Office
EPA 505-F-14-011, 8 pp, 2014.
This fact sheet, developed by the U.S. EPA Federal Facilities Restoration and Reuse Office (FFRRO), provides a brief summary of the emerging contaminant 1,4-Dioxane, including physical and chemical properties; environmental and health impacts; existing federal and state guidelines; detection and treatment methods; and additional sources of information. 1,4-Dioxane is a probable carcinogen and has been found in ground water at sites throughout the United States. The physical and chemical properties and behavior of 1,4-Dioxane create challenges for its characterization and treatment. It is highly mobile and has not been shown to readily biodegrade in the environment. This fact sheet is intended for use by site managers faced with addressing 1,4-Dioxane at cleanup sites or in drinking water supplies and for those in a position to consider whether 1,4-Dioxane should be added to the analytical suite for site investigations.
Environmental Investigation and Remediation: 1,4-Dioxane and Other Solvent Stabilizers
Mohr, T., J. Stickney, and W. DiGuiseppi.
CRC Press, Boca Raton, FL. ISBN: 9781566706629, 550 pp, 2010
This book examines the uses, industrial history, environmental fate, laboratory analysis, toxicology, risk assessment, and treatment of 1,4-dioxane in extensive detail. It also describes the controversy over interpretation of 1,4-dioxane's toxicology and associated risk, as well as the corresponding disparity in state regulation of 1,4-dioxane. Filled with case studies, equations, tables, figures, and citations, the book describes passive and active remediation strategies and treatment technologies for 1,4-dioxane in groundwater.
Groundwater Information Sheet: 1,4 Dioxane
California State Water Resources Control Board, 7 pp, 2009.
This brief groundwater information sheet provides general information (fate and transport, health effects, testing and remediation methods) and identifies where high levels of the compound are found in California. The information is pulled from a variety of sources, and a bibliography is provided.