How 1,4-Dioxane is Manufactured and Used in Various Industries

For as long as there have been computers, air duster products have been cleaning their hardware. Without them, dust collects, builds heat, and can eventually catch computers on fire. However, there’s more than air inside air duster cans. Keeping computers clean requires chemicals, like dry cleaning; some of which are corrosive and harmful to human health. To contain the reactivity of this air duster chemical cocktail that would otherwise dissolve the can before you could buy it, manufacturers rely on 1,4-dioxane.

1,4-dioxane is a colorless liquid, primarily used to stabilize active chemicals in solvents, greases, and detergents. It is sometimes categorized as a “forever chemical” alongside PFAS due to its bio-persistence, solubility in water, and resistance to evaporation, requiring specialized treatment technologies to remove it from water.  

Despite these similarities, the two compounds have different chemical compositions and behaviors.  PFAS compounds consist of carbon-fluorine bonds. They were designed to be extremely stable and resistant to degradation in harsh conditions. By contrast, 1,4-dioxane does not possess the same level of chemical bond stability and breaks down under certain temperature, UV, and atmospheric conditions. Nonetheless, 1,4-dioxane is still resistant to biodegradation and exhibits stability in underground environments, which is why it specifically threatens groundwater sources.  

Furthermore, once released into the environment, 1,4- dioxane plumes expand rapidly through groundwater, due largely to the chemical's relative lack of adsorption to carbon. This enables 1,4-dioxane to contaminate potentially large areas far from the site of its release. After decades of improper discharge to water bodies from 1,4-dioxane-laden industrial processes and landfill leachate, it has contaminated groundwater and surface water, continuously threatening drinking water and public health.  

1,4-dioxane production exploded in the 1980s when it was used to stabilize the active chemicals found in aluminum aerosol cans products, particularly 1,1,1-Trichloroethane (1,1,1-TCA). While 1,1,1-TCA was banned by the Montreal Protocol, 1,4-dioxane continues to provide stability to innumerable industrial manufacturing processes and consumer goods. Because of its broad applications, we can encounter 1,4-dioxane through food packaging, perfumes, and toothpaste.

Manufacturing Processes of 1,4-Dioxane

Producing 1,4-dioxane is like making a panini. A chemical called diethylene glycol (the sandwich) is mixed with an acid (the toaster). The reaction dehydrates (cooks) the diethylene glycol — yielding 1,4-dioxane (the panini). On an industrial scale, this process happens in large metal vats, applying heat and acid to thousands of gallons of diethylene glycol and harvesting the resulting 1,4-dioxane.

In some instances, 1,4-dioxane is manufactured accidentally, particularly during ethoxylation. Ethoxylation is the mixing of ethylene oxide, a diethylene glycol precursor, with other chemicals to make new ones. These novel chemicals are often active ingredients in laundry detergents, cosmetics, agricultural products, clothes dye, and many other household products. Intentional and unintentional widespread production has put 1,4-dioxane down our drains, into our rivers, lakes, and consequently our drinking water for decades.

Use of 1,4-Dioxane in Various Industries

1,4-dioxane’s ability to prevent corrosive chemicals from reacting with their surroundings and its high solubility in water has made it attractive to many industrial applications. From stabilizing chlorine-based waxes to purifying pharmaceuticals, 1,4-dioxane enhances the dispersal of chemicals and dyes, laboratory research projects, and plastics manufacturing.

Industrial Solvent Applications

Solvents selectively strip chemicals and organics, aiding extraction and cleaning processes. 1,4-dioxane’s proclivity to stabilize solvents, as well as its own solvent characteristics, have led to its diverse use in food processing, printer ink production, and plastic water bottle manufacturing.

Detergent Manufacturing

As mentioned above, the ethoxylation process can produce 1,4-dioxane as an accidental byproduct, landing it in cosmetics, detergents, and soaps. The US Food and Drug Administration (FDA) has been monitoring this impurity since the 1980s, reporting that 1,4-dioxane is found in fewer products and at lower concentrations as manufacturers have taken more responsibility to remove it.

Pharmaceutical Manufacturing

Pharmaceutical companies use 1,4-dioxane to strip their products of impurities. As an effective and remarkably stable solvent, 1,4-dioxane is the purifying agent of choice for producing medical pharmaceuticals, veterinary pharmaceuticals, and natural health products. Like in textiles, 1,4-dioxane is used to disperse chemicals during the pharmaceutical manufacturing process to accelerate chemical reactions. Laboratories also use dioxane as a reagent in research work.

These applications and many others have resulted in groundwater contamination prevalence considered by some to be greater than PFAS. Such widespread contamination is particularly troubling as we continue to learn more about the health effects associated with 1,4-dioxane exposure.    

Health Implications of 1,4-Dioxane

While preliminary studies have suggested that 1,4-dioxane is potentially carcinogenic, the EPA's assessment confirms its serious public health threat. The U.S. Environmental Protection Agency (EPA) has determined that 1,4-dioxane presents an unreasonable risk to human health, both from cancer and non-cancer risks to workers and the general public, particularly from exposure through drinking water. This finding was formalized in the EPA’s 2023 Draft Revised Risk Determination and the 2024 final revised risk determination under the Toxic Substances Control Act (TSCA). The agency is now proposing risk management actions to mitigate these risks, which could include regulating industrial uses and consumer products.

The widespread contamination of 1,4-dioxane is particularly alarming due to its classification as a likely carcinogen. Short term exposure to high levels of 1,4-dioxane are reported to cause drowsiness, headache, nausea, and eye irritation. The EPA recently updated its risk assessment for this chemical, estimating that daily consumption of 1,4-dioxane via drinking water poses a cancer risk greater than one in one million people. Animal studies also show increased incidents of liver, gall bladder, and nasal cavity tumors after continued exposure.

Decades of occupational proximity and inadvertent consumption have taken a toll on public health. Beyond cancer risks, research shows that prolonged exposure to 1,4-dioxane can adversely affect organ function, including the liver, kidneys, and the central nervous system. Additionally, pregnant women, infants, and individuals with compromised immune systems may face more severe risks.

Potential for Environmental Contamination

1,4-dioxane’s high solubility in water makes it a tenacious groundwater contaminant. Coupled with the lack of regulations to treat it onsite at industrial sites and landfills, 1,4-dioxane has continuously spread from its industrial origins and entered our air, water, and soil. Oxygen and sunlight degrade 1,4-dioxane quickly, minimizing its air pollution hazards. The stable characteristics that make it an industrial process superstar also prevent it from interacting with soil. This leaves one place for 1,4-dioxane to hide and persist: our groundwater.

Ann Arbor, Michigan, for example has been affected by 1,4-dioxane point source contamination that is so serious that the state is revoking property owner’s ability to drink their well water out of concern for their health. The EPA recently conducted a preliminary assessment of Ann Arbor’s contaminated groundwater and believes the contamination is severe enough to qualify for the Superfund program's National Priorities List, placing it alongside thirty-four other 1,4-dioxane-related Superfund sites on that same list. This long-standing contamination issue is not the fault of the city but rather the result of historical industrial practices.

National and local attention on 1,4-dioxane is growing, triggering some states to enact consumer protection and drinking water guidelines to limit public exposure.

Mitigation and Alternatives

Across the US, state health agencies are passing and considering 1,4-dioxane health advisories and limits; forcing industrial sites and drinking water utilities to consider its presence in their processes regardless of whether or not they produce 1,4-dioxane.  

New York State is leading the way, becoming the first state to develop 1,4-dioxane standards for drinking water and consumer products in 2020. Its dioxane laws establish maximum concentrations limits for:

• Household cleaning and personal care products at one part per million.

• Cosmetics at ten parts per million.

• Drinking water at one part per billion.

These new regulations have forced water utilities, industrial facilities, and consumer product manufacturers alike to change their operations to account for 1,4-dioxane concentrations. While already applied in some processes to remove 1,4-dioxane, more industrial sites will employ vacuum stripping or alternatives to remove 1,4-dioxane from their products before they land on store shelves.

To date, there have been a total of 39 states that have issued health-based advisories, along with New York’s already established MCL of 1 ppb. Other states, including California, New Jersey, Illinois, and Virginia, are working to develop their own MCLs for 1,4-dioxane.

Alternative Chemicals and Processes

1,4-dioxane offers stability to industrial processes that make our modern world possible. But its impact on water quality is likely unaccounted for. In an effort to make modern conveniences more sustainable, chemical companies are creating alternatives to 1,4-dioxane, like 2-Methyltetrahydrofuran.  

Some product formulators have eliminated 1,4-dioxane by avoiding ethoxylated ingredients. However, while unethoxylated surfactants exist, their limited availability and higher cost, the effort required to reformulate product recipes, and consumer perception are barriers to manufacturers’ adoption of alternative surfactants.

Despite government and industrial pushes to stop 1,4-dioxane from entering the environment, its legacy contamination and stability in groundwater means a conscious effort to remove it will be required. As state health agencies move to set drinking water limits on 1,4-dioxane, treatment costs may fall on water utilities and their ratepayers, who are already grappling with lead and copper, aging infrastructure, and PFAS.

To learn more about how your groundwater may be affected by contamination, what actions to take in that scenario, and how to fund its removal, check out our other guides today.