1, 4 – Dioxane

An EPA Factsheet

Introduction

Chemicals can be released to the environment as a result of their manufacture, processing, and use. This fact sheet provides information on dioxane. This fact sheet describes the exposure pathways, the effects of the exposure to humans and the environment; and the fate of the 1, 4-dioxane in the environment.

Physical Properties

• Appearance: colorless liquid
• Melting point: 11.8 C
• Boiling point: 100 - 120 C
• Vapor density: 3
• Vapor pressure: 27 mm Hg at 20 C
• Density (g cm-3): 1.034
• Flash point: 12 C
• Explosion limits: 2% - 22%
• Auto ignition temperature: 180 C
• Stability: Stable. Incompatible with oxidizing agents, oxygen, halogens, reducing agents, moisture.
• Highly flammable - note wide explosive range. May form explosive peroxides in storage (rate of formation increased by heating, evaporation or exposure to light).

What is 1,4-dioxane, how is it used, and how might one be exposed to it?

Exposure to dioxane can occur in the workplace or in the environment following releases to air, water, land, or groundwater. It enters the body when people breathe air or consume water or food contaminated with dioxane. It can also be absorbed through skin contact. It does not remain in the body due to its breakdown and removal.

What happens to 1,4 - dioxane in the environment?

1,4-dioxane can evaporate when exposed to air. It mixes easily with water. Most references of 1,4-dioxane to the U.S. environment are to air and surface water. Once in air, it breaks down to other chemicals. 1,4-Dioxane can evaporate from dry soil exposed to air. It is not likely to evaporate as readily from water or moist soil. Because it is a liquid that does not bind well to soil, dioxane that makes its way into the ground can move through the ground and enter groundwater. Plants and animals are not likely to store 1,4-dioxane. The environmental release, transport and transformation/ persistence of dioxane is explained below in detail.

A. Environmental Release

Of the total 1.13 million pounds of 1,4-dioxane released into the U.S. environment in 1992, as reported to the Toxics Release Inventory by certain types of U.S. industries, 680 thousand pounds were released into the atmosphere, 450 thousand pounds were released into surface waters, and 33 hundred pounds were released onto the land (TRI92 1994). 1,4-Dioxane at a concentration of 1 microgram/L has been detected in drinking water in the U.S., (no specific locations given); the chemical was detected in 37% of well water samples collected near a solid waste landfill located 60 miles southwest of Wilmington, DE. 1,4-Dioxane at 1 microgram/L was detected in the Chicago Sanitary and Ship Channel.

B. Transport

The low estimated soil-sorption coefficient (Koc), indicates that 1,4-dioxane should readily leach to ground water. The estimated Henry's Law constant suggests that volatilization from moist soils will be slow. Based on its vapor pressure, volatilization from dry soils should be fast. 1,4-dioxane is not expected to adsorb significantly to suspended sediments (Howard 1990).

C. Transformation/Persistence

1. Air
1,4-Dioxane in the atmosphere is expected to degrade fairly quickly. The half-life of the reaction of 1,4-dioxane with photochemically produced hydroxyl radicals in the atmosphere was estimated to be 6.7-9.6 hours. Experimental results of sunlight-irradiated
mixtures of 1,4-dioxane/NO suggest similar half-lives (Howard 1990).

2. Soil
No adsorption data are available, but the low estimated log soil-sorption coefficient (Koc) suggests that 1,4-dioxane should readily leach to ground water.
No data concerning the volatilization of 1,4-dioxane are available, but the estimated Henry's Law constant suggests that volatilization from moist soils will be slow; however, based on its vapor pressure, volatilization from dry soils should be fast. 1,4-dioxane is not expected to biodegrade in soil (Howard 1990).

3. Water
No hydrolysis data on 1,4-dioxane are available. Because ethers in general have been classified as generally resistant to hydrolysis, 1,4-dioxane is not expected to hydrolyze significantly. The estimated Henry's Law constant for 1,4-dioxane and its miscibility in water suggest that volatilization will be slow. From its estimated Koc, 1,4-dioxane is not expected to significantly adsorb to suspended sediments. 1,4-Dioxane is not expected to biodegrade in water (Howard 1990).

4. Biota
Based on its log P, 1,4-Dioxane is not expected to bioconcentrate in fish (Howard 1990).

How does 1,4 - dioxane affect human health and the environment?

Effects of 1,4-dioxane on human health and the environment depend on how much 1,4-dioxane is present and the length and frequency of exposure. Effects also depend on the health of a person or the condition of the environment when exposure occurs.

Breathing 1,4-dioxane for short periods of time causes irritation of the eyes, nose and throat in humans. Exposure to large amounts of 1,4-dioxane can cause kidney and liver damage. Accidental worker exposure to large amounts of 1,4-dioxane has resulted in several deaths. Symptoms associated with these industrial deaths suggest 1,4-dioxane causes adverse nervous system effects. These acute effects are not likely to occur at concentrations of 1,4-dioxane that are normally found in the U.S. environment.

Limited evidence suggests that repeatedly breathing small amounts of 1,4-dioxane over long periods of time causes no adverse effects in workers. Laboratory studies show that exposure to 1,4-dioxane over a lifetime causes cancer in animals. 1,4-Dioxane may likewise cause cancer in humans. Laboratory studies sow that repeat exposure to large amounts of 1,4-dioxane in drinking water, in air, or on the skin causes liver and kidney damage in animals.

This fact sheet has been adapted from U.S. EPA's website .
Last updated on September, 2003

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