For more than two decades now, the presence of 1,4-dioxane in the environment has had increasing focus by many regulatory agencies across the United States, based on its designation by the United States Environmental Protection Agency as “likely to be carcinogenic to humans” by all routes of exposure. The physical and chemical properties and behavior of 1,4-dioxane create unique challenges for its characterization and treatment. [i]
What is it and where does it come from?
1,4-dioxane is a volatile, colorless liquid with a mild pleasant odor and relatively low volatility. It is highly soluble in a wide variety of matricies including; water, alcohol, ether, most organic solvents, aromatic hydrocarbons, and oils. 1,4-dioxane is an ether similar to methyl-tert-butyl ether (“MTBE”) and has many of the same physical properties. Environmentally, it is very soluble and highly mobile in groundwater, but does not adsorb well to soil particles and does not readily biodegrade.
1,4-dioxane is one of several stabilizers historically used in industry to enhance the functional life of solvents. It was also used as a solvent for impregnating cellulose acetate membrane filters; as a wetting and dispersing agent in textile processes; and as a laboratory cryoscopic solvent for molecular mass determinations. In 1995, according to USEPA nearly 90 percent of 1,4-dioxane produced commercially in the United States was used as a stabilizer for chlorinated solvents, in particular 1,1,1-trichloroethane (“1,1,1-TCA”) at up to 8 percent by volume. However, this use is no longer expected to be important due to the 1990 Amendments to the Clean Air Act and the Montreal Protocol, which mandate the eventual phase-out of 1,1,1-trichloroethane production in the United States. [i] [ii] [iii]
The remaining 10 percent of 1,4-dioxane is used in a wide variety of commercial applications and formulations including; as a degreasing agent, as a component in paint and varnish removers, as a wetting agent in the textile industry, as a solvent in chemical synthesis, as a fluid for scintillation counting, as an additive in deicing fluids, and as a solvent in coatings, sealants, adhesives, and pharmaceuticals. 1,4-dioxane was or is currently present in detergents, shampoos, deodorants, cosmetics, antifreeze, and is found in many landfill leachates. Surfactants containing 1,4-dioxane are used in a wide variety of products including foods, cosmetics, and detergents. The 1,4-dioxane in these products is thought to be a by-product from the polymerization of ethylene oxide during production. [iv] [v] [vi]
Why the interest now?
Groundwater beneath the city of Ann Arbor, Michigan contains 1,4-dioxane. This chemical was used as an industrial solvent by Gelman Sciences and later Pall Life Sciences’ (“Gelman/Pall”). Between 1976 and 1985, process water containing 1,4-dioxane was reportedly sprayed on lawns and stored in unlined lagoons at the Gelman/Pall site on the southwest side of Ann Arbor. Disposal of this chemical at the Gelman/Pall site stopped in 1986. The physical properties of 1,4-dioxane allow it to easily mix and move with groundwater such that it traveled through soil and rock layers into the groundwater and began to migrate with the local and regional groundwater. Today, 1,4-dioxane from the Gelman/Pall site is found in a deep groundwater aquifer called Unit E. [vii]
The State of Michigan generic residential cleanup criterion for drinking water for 1,4-dioxane was set years ago 85 parts per billion (ppb) based on 1 in 100,000 additional cancer risk. Historically, groundwater must be at or below this level in order to allow for its unrestricted use, including use as drinking water. In 2010, the USEPA established a more stringent 1,4-dioxane carcinogenic slope factor, effectively lowering the USEPA residential drinking water criterion for 1,4-dioxane to 3.5 ppb based on 1 in 100,000 additional cancer risk. In March 2016, the Michigan Department of Environmental Quality (“MDEQ”) proposed a generic residential cleanup criterion for drinking water for 1,4-dioxane of 7.2 ppb based on 1 in 100,000 additional cancer risk. However, there is no guarantee that this proposed standard will be implemented. [viii]
What if I want my water tested?
If your water is not already being tested but you would like to test it, you are responsible for any cost. ATS has been located in the Ann Arbor community since it was founded in 1983. ATS is a privately held company, conveniently located on the southwest side of Ann Arbor, Michigan at 290 South Wagner Road. ATS maintains 5,000 sq. ft. of in-house chemistry laboratories to characterize gaseous, liquid, and solid samples for a with a wide range of analyses, including 1,4-dioxane. The ATS laboratories are of modern design, highly-automated and equipped with state-of-the-art instrumentation to provide world class chemical analysis capabilities. ATS maintains primary laboratory certification in the State of Michigan for Drinking Water and secondary certifications in other states and agencies through reciprocity. Please note that only the MDEQ Drinking Water Laboratory automatically provides copies of test results to Washtenaw County Public Health.
Analytical methodology employed in ATS laboratories follows standards published by the USEPA, ATSM International (“ASTM”), American Public Health Association (“APHA”), America National Institute for Occupational Safety and Health (“NIOSH”), and other standard setting entities. When standard methodology is not available, or where an alternate analytical approach is required, ATS has the unique ability to develop, performance validate, and certify custom methods to regulatory standards that provide an acceptable resolution to the issues of sensitivity, selectivity, accuracy and precision. As an example, in 1986 ATS chemists developed a site-specific method for analysis of 1,4-dioxane in groundwater, surface water, wastewater, consumer products, and other environmental media. The ATS method for 1,4-dioxane is based on USEPA Method 1624 which uses dynamic headspace purging and isotope dilution gas chromatography/mass spectrometry (“GC/MS”) to detect and quantify 1,4-dioxane. Currently, the statistically derived detection limit (“MDL”) for this method in water and wastewater is 0.3 μg/L or ppb. This method was later uniquely cited by the State of Michigan in Operational Memoranda as the required protocol for the analysis of 1,4-dioxane in environmental media.
How do I get my water tested for 1,4-dioxane or other constituents?
The ATS Laboratory offers services for the analysis of drinking water quality. These services include select chemical and microbiological testing procedures currently used for this purpose by state and local water supply programs.
For more information regarding drinking water analyses:
Telephone (734) 995-0995
Select one of the following options.
Download Guidance for Drinking Water Sample Collection
Where can I obtain additional information about 1,4-dioxane?
If you have questions about Gelman/Pall groundwater contamination site, please contact:
State of Michigan Site Contamination & Remediation, Dan Hamel, Telephone (517) 780-7832
State of Michigan NPDES Permit, Jeffrey Surfus, Telephone (517) 780-7921
State of Michigan Drinking Water, Lois Graham, Telephone (517) 284-6530
[i] ATSDR 2012. Agency for Toxic Substances and Disease Registry “Toxicological Profile for 1,4-Dioxane.”
[ii] DHHS 2011. United States Department of Health and Human Services. “Report on Carcinogens, Twelfth Edition.” Public Health Service, National Toxicology Program. 12th Edition.
[iii] USEPA 2006. United States Environmental Protection Agency. “Treatment Technologies for 1,4-Dioxane: Fundamentals and Field Applications.” EPA 542-R-06-009.
[iv] ATSDR 2007. Agency for Toxic Substances and Disease Registry. Toxicological profile for 1,4-Dioxane. Draft for public comment. US Department of Health and Human Services, Public Health Service, Agency for Toxic Substances and Disease. Atlanta, GA.
[v] USEPA 1990. United States Environmental Protection Agency. Amendments to the Clean Air Act. Sec. 604. Phase-out of production and consumption of class I substances.
[vi] UNEP (2000). United Nations Environment Programme. The Montreal Protocol on substances that deplete the ozone layer. Ozone Secretariat. Nairobi, Kenya.
[vii] MDEQ 2007. Michigan Department of Environmental Quality. Prohibition Zone – Groundwater Use Restrictions, Gelman Sciences, Inc., Unit E Aquifer 1,4-Dioxane Groundwater Contamination Fact Sheet. March 2007.
[viii] AACTBT 2016. Ann Arbor Charter Township Board of Trustees. Resolution Supporting a Petition to USEPA for the Gelman Sciences, Inc. Site to Be Designated as a Superfund Site. March 21, 2016.