The Problem with 1,4-Dioxane

Oral Presentation

Prepared by C. Hiegel1, M. Wilken2, C. Ballek1
1 - Trihydro Corporation, 1252 Commerce Dr. , Laramie, WY, 82070, United States
2 - The Dow Chemical Company - Environmental Remediation and Restoration Technology Team, 1790 Building, Office 225, Midland, MI, 48674,

Contact Information:; 307-745-7474


1,4-Dioxane (1,4-dioxacyclohexane) was identified by the United States Environmental Protection Agency (EPA) as an emerging contaminant of concern in 2008. Its use is widespread and prevalent: as a solvent stabilizer with 1,1,1-trichloroethane (TCA); in many consumer products; as a by-product of plastics manufacturing; and as an ingredient or contaminant in many of the most commonly used pesticides and herbicides.

The EPA has classified 1,4-dioxane as “likely to be carcinogenic to humans,” and in 1988, it was added to the California list of “chemicals known to the state to cause cancer." Because of the toxicity of 1,4-dioxane (C4H8O2), its potential carcinogenic effects, the multiple potential sources for environmental contamination, and its rapid movement through groundwater, regulatory agencies are setting action limits for cleanup of the compound at low concentrations. However, screening levels vary widely from state to state. Some of the other inherent environmental and analytical problems with 1,4-dioxane include:

- At active or closed chlorinated remediation sites, 1,4-dioxane may not have been on target analyte lists previously. It is highly mobile, (soil/water partitioning factor (Koc) of 17), and once identified and quantified, it can increase the size of the groundwater plume or can be a “reopener” for closed sites.
- The boiling point of 1,4-dioxane (101.1°C) classifies it as a volatile organic compound (VOC) for analytical purposes. The traditional procedures for analysis of VOCs using purge and trap methods suffer from poor sensitivity since 1,4-dioxane is miscible in water and thus the purge efficiency (removal of the analyte from the water matrix) is very low. The high solubility of 1,4-dioxane in water also in results in difficulties generating reproducible results since efforts to enhance the detection of the target analyte can result in the introduction of water vapor into the analytical system creating active sites on GC columns that interfere with subsequent analyses.
- The combination of the physical and chemical characteristics of 1,4-dioxane result in unique behavior in the environment: it is unstable at elevated temperatures and pressures; it is explosive when exposed to light or air; it is weakly retarded by sorption to soil particles; it is relatively resistant to biodegradation; and the common remediation techniques of air-stripping and granular activated charcoal do not treat this persistent chemical.

This presentation will focus on the problems and potential solutions that have been used to identify and remediate 1,4-dioxane and will work to open a dialogue to find the best method for reliable analysis of 1,4-dioxane at detection limits that meet regulatory requirements.