1,4-Dioxane in Drinking Water: Risks, Sources, and Health Impacts


Clean drinking water is the foundation of thriving, healthy communities. Water providers maintain this foundation by ensuring their community's water supply and customers' taps are free of harmful contaminants. However, this can be difficult in a world grappling with industrial pollution. One concerning contaminant that has gained renewed attention from the news, regulators, and the public is 1,4-dioxane.  With a remarkable ability to dissolve and travel through ground and surface water, the synthetic chemical poses potentially widespread public health risks, making it crucial for water utilities nationwide to be well-informed and proactive in addressing any possible 1,4-dioxane contamination of their water sources.

Understanding 1,4-Dioxane

1,4-Dioxane is a colorless liquid primarily used as a stabilizer in various industrial applications, such as solvents, greases, and waxes. A highly flammable chemical, its aversion to being absorbed in soil and high solubility in water make it more widespread than similar pollutants. After decades of use in industrial processes and consumer products, it has a pervasive presence in the environment, particularly ground and surface water.

1,4-dioxane is sometimes deemed a forever chemical due to its bio-persistence, meaning it does not readily degrade. While it features similar characteristics to forever chemicals like PFAS, 1,4-dioxane is not technically a forever chemical. However, its ability to dissolve and resistance to evaporation make removal with conventional water treatment solutions challenging. As a result, 1,4-dioxane persists in the environment for long periods, continuously threatening water sources and public health. Through prolonged exposure via drinking water and air, the EPA finds that a list of potential health risks like internal organ failure, irritated skin, and cancer are likely caused by 1,4-dioxane.

Impact of 1,4-Dioxane on Public Health

Recent studies conducted by the Environmental Protection Agency (EPA) and other health organizations have raised red flags regarding this contaminant's potential health effects.

Of particular concern is 1,4-dioxane's classification as a likely human carcinogen. In the EPA’s 2023 supplement to the risk evaluation of 1,4-dioxane, it was stated that the chemical had "Cancer risk estimates higher than one in one million for a range of general population exposure scenarios, including to fence-line communities associated with drinking water sourced downstream of release sites and for air within one km of releasing facilities." As seen with other contaminants, being listed in the National Primary Drinking Water Regulations (NPDWR) Maximum Contaminant Limits (MCL), coupled with the focus on risks from ambient air and drinking water in the Draft Supplement to the Risk Evaluation for 1,4-Dioxane recently released for public comment suggests future regulation.

Beyond cancer risks, research has shown that 1,4-dioxane can adversely affect organ function, including the liver, kidneys, and the central nervous system. Additionally, vulnerable populations, such as pregnant women, infants, and individuals with compromised immune systems, may face more severe risks from 1,4-dioxane exposure.

Seminole County, which contains part of Orlando, Florida, is an example of a community recently reeling from 1,4-dioxane’s health effects. The Floridan Aquifer supplies nearly all the drinking water for communities in Seminole County and is considered one of the most active aquifers in the country. After detecting 1,4-dioxane in the aquifer, the former Siemens factory in Lake Mary was identified as a potential contamination source, as it had a history of improper chemical handling and environmental violations. Former Siemens employees reported careless handling and dozens later developed cancer and attributed it to exposure to toxic chemicals at the factory. Despite confirming 1,4-dioxane contamination at the Siemens site in 2001, local water utilities only began testing for its presence in drinking water about a dozen years later.

The EPA's Unregulated Contaminant Monitoring Rule 3 (UCMR 3) inclusion of 1,4-dioxane as a groundwater contaminant of concern should also give water providers reason to consider its potential to join the NPDWR’s MCL list. Under the UCMR's reporting requirements, communities have discovered 1,4-dioxane levels as high as 2,400 parts per billion (ppb) at their water sources, in the worst cases. This designation, and its preliminary reporting data, underscores the need for immediate attention and proactive action from water utilities nationwide to address 1,4-dioxane's presence in drinking water sources and potential impacts on public health.

Sources of 1,4-Dioxane Contamination

To effectively combat 1,4-dioxane contamination, it is crucial to identify its sources. The chemical can enter water bodies through various routes, including direct discharge from industrial facilities, improper disposal of consumer products, and landfill leachate.

Historically, 1,4-dioxane contamination arose from unregulated industrial practices, where spent or unwanted solvents were legally dumped into unlined ponds or leaked from underground storage tanks. In 1,4-dioxane’s case, leaching out of landfills, infiltrating aquifers, and contaminating groundwater is common. Personal care products, such as shampoos, detergents, and cleaning agents, can also contain 1,4-dioxane as a byproduct. With personal care products, the chemical ultimately finds its way into water sources via wastewater treatment discharge, as these facilities are not mandated to remove the contaminant.

In Ann Arbor, Michigan, 1,4-dioxane contamination is so serious that the city's water source is being considered for Superfund status. The U.S. EPA recently conducted a preliminary assessment of a contaminated groundwater plume in the Ann Arbor area and believes the contamination is severe enough to qualify for the Superfund program's National Priorities List. The 1,4-dioxane plume spread in the region's groundwater for many years, consequently affecting surrounding townships’ water as well. A final decision on Superfund inclusion might be made as soon as fall 2024, with a cleanup plan taking several additional years to develop.

With years of work ahead, identifying and controlling these legacy sources of 1,4-dioxane contamination in your community and neighboring communities is essential for preventing its spread and curtailing potential and existing community health risks nationally.

1,4-Dioxane Guidelines and Regulations

While the EPA has yet to establish a federal MCL for 1,4-dioxane in drinking water, several states have various non-regulatory cleanup and health-based standards for the chemical, yet most states do not have 1,4-dioxane drinking water regulations in place.

After discovering numerous contaminations, New York became the first state to set a 1,4-dioxane drinking water MCL of one ppb in 2020. Similarly, New Jersey issued a recommended MCL of 0.33 ppb in December 2021, and California established a notification level of one ppb and a response level of 35 ppb.

These state-level regulations forecast a growing national concern over 1,4-dioxane’s potential health risks and possible regulatory action from the EPA in the near future. They emphasize the importance of monitoring 1,4-dioxane and creating an action plan to address its presence in water sources and the drinking water distributed to customers.

What can we expect from future regulations?

The regulatory landscape for 1,4-dioxane is evolving rapidly. California, Illinois, and New York are among the states that have already established benchmarks to combat the chemical’s presence in drinking water. The EPA's recent supplement to 1,4-Dioxane’s risk evaluation shows regulatory advancement and will influence upcoming regulatory decisions at the federal level.

Considering the precedent set by emerging contaminants like PFAS, it is evident that regulatory actions can move swiftly once awareness and scientific evidence catch up. For water utilities, taking proactive steps to prepare for potential regulations will serve your communities well. With a 1,4-dioxane mitigation plan, you can begin protecting your water source, considering pragmatic treatment solutions, and preserving your customers' health to demonstrate a commitment to their livelihood.

It is worth noting that the regulatory process is complex and may take time. However, being proactive can yield significant future financial and public confidence by ensuring your water utility is prepared for upcoming regulations and guidelines.

Start the Process of Contamination Preparation

As we navigate the complexities of 1,4-dioxane contamination, your proactive actions as water utilities are critical. Addressing potential contamination early will safeguard public health and maintain public trust in your water supply.

If your water utility has not already, consider conducting a water quality test to identify 1,4-dioxane contamination levels at your water source(s). Collaborating with environmental experts, relevant regulatory bodies, and local industry stakeholders will help you develop targeted strategies to address contamination effectively. By acting now and being prepared for potential regulatory changes, water providers can create a roadmap to stay ahead of the curve and protect your community's health and well-being.

Whether 1,4-dioxane will follow the same regulatory path as similar contaminants remains to be seen. However, some communities have already been obligated to invest in remediation and treatment, and many others may follow. Regardless of which treatment method is best for your water system, it will likely come with costs that you or your ratepayers may be forced to bear. If you suspect 1,4-dioxane has contaminated your water supply, it may make sense to explore whether litigation is the avenue to recoup some of those costs. SL Environmental focuses on contamination cases and works on a contingency fee, meaning your utility only incurs legal expenses once compensation is awarded. 

Contact the team at SL Environmental Law Group to learn more about proactive measures and strategies to address contamination concerns.