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



1, 4-Dioxane generally is used as a solvent or intermediate. Only one manufacturer now produces the compound in the United States. Production of the chemical has fallen significantly from the nearly 15 million pounds produced in 1982, possibly because all but critical uses of trichloroethane, to which it was added as a stabilizer, have been banned in this country. According to the Toxic Release Inventory for 2009, 69,358 pounds of 1,4-Dioxane were released to the air, 45,146 to surface waters, none to land, and 136,034 pounds were transferred from the user to off-site disposal.

Due to its widespread use as a stabilizer for chlorinated solvents, the chemical is detected frequently at sites contaminated with chlorinated solvents. Because conventional pump-and-treat technologies such as air stripping and carbon adsorption do not capture the compound, reinjection of treated ground water from which 1,4-dioxane has not been adequately removed has resulted in shutdown of domestic and municipal supply wells. 1,4-Dioxane has been found in the ground water of several Superfund sites and has become a chemical of concern for drinking water supplies in California.

The primary routes of potential human exposure to 1,4-dioxane are inhalation, ingestion, and dermal contact. 1,4-Dioxane can be formed as a byproduct of reactions based on condensing ethylene oxide or ethylene glycol during the production of certain consumer products. Exposure of the general population to 1,4-dioxane might occur from contact with products containing residues of the compound. According to the Consumer Product Safety Commission (CPSC), consumers could be exposed to residual levels of 1,4-dioxane formed during the manufacture of detergents, shampoos, surfactants, and certain pharmaceuticals. CPSC reported that the presence of 1,4-dioxane, even as a trace contaminant, is cause for concern, and the Commission continues to monitor its use in consumer products. Residues can be present in food packaged in 1,4-dioxane-containing materials, or on food crops treated with pesticides containing 1,4-dioxane. The compound has been noted as a component in vine-ripened tomatoes and tomato products, fresh shrimps, brewed coffee and fried chicken. Potential occupational exposure to 1,4-dioxane could occur during its production and use as a stabilizer or solvent.

Adapted from:

Adobe PDF Logo1,4-Dioxane, CAS No. 123-91-1, Report on Carcinogens, 12th ed.
U.S. Department of Health and Human Services, 2011.

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

The 2001 Toxics Release Inventory (TRI) Public Data Release Report
EPA 260-R-03-001, 2003

U.S. International Trade Commission: Synthetic Organic Chemicals, United States Production and Sales USITC Publication Number 1588.

1,4-Dioxane Drinking Water Occurrence Data from the Third Unregulated Contaminant Monitoring Rule (Abstract)
Adamson, D.T., E.A. Pina, A.E. Cartwright, S.R. Rauch, R.H. Anderson, T. Mohr, J.A. Connor.
Science of the Total Environment 596-597:236-245(2017)

Data collected from U.S. public drinking water supplies in support of the third round of the Unregulated Contaminant Monitoring Rule (UCMR3) were evaluated to better understand the persistence of 1,4-dioxane and the importance of groundwater contamination for potential exposure. 1,4-Dioxane was detected in samples from 21% of 4864 PWSs, and was in exceedance of the health-based reference concentration (0.35 µg/L) at 6.9% of these systems. In both measures, it ranked second among the 28 UCMR3 contaminants. The detection frequency for 1,4-dioxane in surface water was only marginally lower than in groundwater, but groundwater concentrations were higher and contributed to a higher frequency of exceeding the reference concentration, indicating that surface water sources tend to be more dilute. 1,4-Dioxane detections in drinking water were highly associated with detections of other chlorinated compounds particularly 1,1-DCA, which is associated with the release of 1,4-dioxane as a chlorinated solvent stabilizer. Based on aggregated nationwide data, 1,4-dioxane showed evidence of a decreasing trend in concentration and detection frequency over time.

Bally Groundwater Contamination Superfund Site Progress Profile
Bally Borough, Berks County, PA.

Adobe PDF LogoGeohydrology, Water Quality, and Simulation of Ground-Water Flow in the Vicinity of a Former Waste-Oil Refinery near Westville, Indiana, 1997-2000
R. Duwelius, D. Yeskis, J. Wilson, and B. Robinson.
U.S. Geological Society Water-Resources Investigations Report 01-4221, 169 pp, 2002.
Contact: Richard Duwelius, rfduweli@usgs.gov

Implications of Matrix Diffusion on 1,4-Dioxane Persistence at Contaminated Groundwater Sites (Abstract)
Adamson, D.T., P.C. de Blanc, S.K. Farhat, and C.J. Newell. Science of the Total Environment 562:98-107(2016)

In a study of the extent to which 1,4-dioxane's persistence was subject to diffusion of mass into and out of lower-permeability zones relative to co-released chlorinated solvents, two release scenarios were evaluated within a 2-layer aquifer system using an analytical modeling approach. The first scenario simulated a dioxane and 1,1,1-TCA source zone where spent solvent was released. The period when dioxane was actively loading the low-permeability layer within the source zone was estimated to be <3 yr due to its high effective solubility. While this was roughly an order of magnitude shorter than the loading period for 1,1,1-TCA, the mass of dioxane stored within the low-permeability zone at the end of the simulation period (26 kg) was larger than that predicted for 1,1,1-TCA (17 kg). Even 80 yr after release, the aqueous dioxane concentration was still several orders of magnitude higher than potentially applicable criteria. Within the downgradient plume, diffusion contributed to higher concentrations and enhanced penetration of dioxane into the low-permeability zones relative to 1,1,1-TCA. In the second scenario, elevated dioxane concentrations were predicted at a site affected by migration of a weak source from an upgradient site. Plume cutoff was beneficial because it could be implemented in time to prevent further loading of the low-permeability zone at the downgradient site. Overall, this study documented that dioxane within transmissive portions of the source zone is quickly depleted due to characteristics that favor both diffusion-based storage and groundwater transport, leaving little mass to treat using conventional means. Results also highlight differences between dioxane and chlorinated solvent source zones, suggesting that back diffusion of dioxane mass might be serving as a dominant long-term secondary source at many contaminated sites.

A Multi-Site Survey to Identify the Scale of the 1,4-Dioxane Problem at Contaminated Groundwater Sites (Abstract)
Adamson, D.T., S. Mahendra, K.L. Walker, S.R. Rauch, S. Sengupta, and C.J. Newell. Environmental Science & Technology Letters 1(5)254-258(2014)

In an evaluation of >2,000 sites in California where groundwater has been affected by chlorinated solvents and/or 1,4-dioxane (dioxane), dioxane was detected at 194 of the sites, with 95% containing one or more chlorinated solvents. Although dioxane frequently co-occurs with 1,1,1-TCA (76% of the study sites), no dioxane analyses were conducted at 332 (67%) of the 1,1,1-TCA detection sites. At sites where dioxane has been identified, plumes are dilute but not large (median maximal concentration of 365 µg/L; median plume length of 269 m) and have been delineated to a similar extent as typically co-occurring chlorinated solvents. At sites where dioxane and chlorinated solvents co-occur, dioxane plumes frequently are shorter than the chlorinated solvent plumes (62%). Study results suggest that dioxane has not migrated beyond chlorinated solvent plumes and existing monitoring networks at the majority of sites, and that the primary risk is the large number of sites where dioxane likely is present but has not been identified.

Solvents Study
U.S. EPA, Office of Solid Waste, EPA 530-R-96-017, 52 pp, 1996.
Ron Josephson, josephson.ron@epa.gov

Undertaken as a result of a consent decree between EPA and the Environmental Defense Fund, this final report of the study on spent solvents discusses the wastes associated with the use of the materials as solvents, the toxicity of the wastes, and the management practices for the wastes. The chemicals addressed in this study are diethylamine, aniline, ethylene oxide, allyl chloride, 1,4-dioxane, 1,1-dichloroethylene, and bromoform.

Adobe PDF LogoTucson Airport Remediation Project (TARP) (Part of the TIAA CERCLA Site)
Arizona Department of Environmental Quality.
Contact: Bill Ellett, ellett.william@ev.state.az.us