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CAS Number: 123-91-1
Synonyms: diethylene dioxide, diethylene ether, dioxane, glycol ethylene ether, p-dioxane
Contaminant Type: Chemical

1,4-dioxane is a volatile organic compound (VOC) that is produced commercially through the dehydration and ring closure of diethylene glycol.  Historically, 1,4-dioxane was used as a stabilizer for the solvent 1,1,1-trichloroethane.  With legislation in the 1990s aimed to phase out 1,1,1-trichloroethane (Clean Air Act, Montreal Protocol), production of 1,4-dioxane as a stabilizer has decreased.  Today, 1,4-dioxane is primarily used as a solvent for celluloses, organic products, lacquers, paints, cosmetics, deodorants, emulsions, and adhesives [2062].

In 1992, of the 1.13 million pounds of 1,4-dioxane released into the U.S. environment, roughly 60 percent was released into the atmosphere, 40 percent into surface waters, and less than one percent onto land.  1,4-dioxane's low soil-sorption coefficient, complete miscibility with water, and resistance to biodegradation contribute to the ability of 1,4-dioxane to leach into and remain in groundwater.  1,4-dioxane has been detected in surface and groundwater samples, in wastewater treatment plant effluents, and in 31 of the 1,689 sites on EPA's National Priorities List [2051].

The EPA classifies 1,4-dioxane as a Group B2 probable human carcinogen by all routes of exposure.  Inhalation is the most common route of exposure; however, exposure may occur through ingestion of contaminated food and water or dermal contact.  Exposure to 1,4-dioxane in tap water through inhalation during showering or other indoor activities can result in higher exposure compared to ingestion of drinking water [2062].  Acute side effects include irritation of the eyes, nose, throat and lungs; possible drowsiness; vertigo; headache; and anorexia.  Human and animal studies identify the liver and kidneys as the target organs for 1,4-dioxane toxicity following short-term exposure to high doses of 1,4-dioxane (regardless of the route of exposure) [2062].  Chronic exposure may result in dermatitis or possible liver and kidney damage.  The reproductive effects are unknown [2051].

As a solvent, 1,4-dioxane can be regulated as a hazardous waste; however, no federal drinking water standards have been established.  The EPA classifies 1,4-dioxane as an emerging contaminant and includes it in the Third Drinking Water Contaminant Candidate List (CCL3).  It is also a proposed contaminant for third Unregulated Contaminant Monitoring Rule program (UCMR 3).  State regulators use drinking water action levels and health advisories to establish site cleanup goals.  In September 2004, Colorado became the first state to establish an enforceable cleanup standard for 1,4-dioxane in groundwater and surface water. This standard is being phased in and requires facilities to have met a 6.1 μg/L limit by March 2005 and a 3.2 μg/L limit by March 2012 [2051].

Pump and treat remediation is the primary method used when remediating sites contaminated with 1,4-dioxane.  Advanced oxidation processes involving hydrogen peroxide with ultraviolet (UV) light or ozone are used to breakdown 1,4-dioxane [2051].  Some of the degradates include aldehydes, organic acids, and the mono- and diformate esters of 1,2-ethanediol [2070].  Other remediation treatment technologies include photocatalysis and soil vapor extraction [2051].  14-dioxane is not well controlled by adsorption onto activated carbon or by air stripping.  it is not well degraded by typical soil microorganisms [2142].

Date of literature search: March 2011

2051 USEPA; 2010; Emerging contaminant - 1,4-dioxane; http://www.epa.gov/fedfac/documents/emerging_contaminant_1,4-dioxane.pdf; As posted on June 15, 2011. EPA Federal Facilities Restoration and Reuse Office (FFRRO), Washington, DC
2062 U.S. Department of Health and Human Services: Public Health Service Agency for Toxic Substances and Disease Registry ; 2007; DRAFT Toxicological Profile for 1,4-Dioxane; DRAFT Toxicological Profile for 1,4-Dioxane; 131-133: U.S. Department of Health and Human Services
2070 Stefan, M. and Bolton, J.; 1998; Mechanism of the degradation of 1,4-dioxane in dilute aqueous solution using the UV/hydrogen peroxide process; Environ. Sci. Technol.; 32:11:1588
2142 Fielder, Linda; 2011; 1,4-Dioxane; http://www.clu-in.org/contaminantfocus/default.focus/sec/1,4-dioxane/cat/overview; USEPA Contaminated Site Clean Up Information