1,4-Dioxane is a Serious Health Risk

On November 13, 2024, the U.S. Environmental Protection Agency (EPA) finalized a new risk assessment for 1,4-dioxane, a chemical found in industrial discharges and some consumer products.

The EPA determined that 1,4-dioxane poses an unreasonable risk to human health, particularly through drinking water contamination and workplace exposure. This decision builds on a 2023 evaluation that incorporated public feedback, peer reviews, and new learnings.

What Does This Mean?

The EPA’s updated evaluation highlights the significant health risks of 1,4-dioxane, including cancer and other non-cancer effects. Key concerns include contamination of drinking water from industrial discharges and consumer product residues. The EPA now uses a whole-chemical approach, looking at risks across all uses of 1,4-dioxane rather than focusing on individual uses.

What Changed in the Final Determination?

The EPA’s earlier evaluations underestimated some risks. For example:

- Surface cleaners: Previously deemed safe, these are now considered risky for nearby communities due to the increased potential for drinking water contamination.

- Laundry and dishwashing products: Initially thought to pose risks only in occupational settings, these are now linked to broader public exposure through contaminated water.

The updated evaluation used new data, such as findings from New York state regulators, showing elevated concentrations of 1,4-dioxane in consumer products. EPA also adopted a more precautionary cancer risk model, assuming no safe exposure threshold.

Health Risks of Drinking 1,4-Dioxane

Drinking water contaminated with 1,4-dioxane poses several health risks:

1. Probable Human Carcinogen: The U.S. Environmental Protection Agency (EPA) classifies 1,4-dioxane as “likely to be carcinogenic to humans” based on studies in animals that showed tumors in the liver, kidneys, and nasal cavities. Long-term exposure, even at low levels, may increase the risk of developing cancer, particularly liver cancer.
2. Liver and Kidney Damage: Prolonged exposure to 1,4-dioxane can harm the liver and kidneys, leading to impaired function and/or structural damage.
3. Respiratory Issues (if inhaled in mist form): Although less common from drinking water, inhalation of vapors during activities like showering or bathing with contaminated water can irritate the respiratory tract.
4. Central Nervous System (CNS) Effects: High doses (typically in occupational settings) have been linked to dizziness, headaches, and drowsiness.
5. Skin and Eye Irritation: In cases of direct exposure (e.g., through bathing or washing), 1,4-dioxane may irritate the skin, eyes, and sensitive mucous membranes.

Risk Amplifiers

Certain populations are at higher risk from 1,4-dioxane exposure, including:

• Infants and young children: Higher vulnerability due to lower body weight and developing organs.
• Individuals with weakened immune systems: More susceptible to long-term effects.
• Fenceline communities: Those living near industrial discharge sites where 1,4-dioxane contamination is higher.

Regulatory Focus

The EPA’s updated risk assessments emphasize that there is no established safe threshold for exposure to 1,4-dioxane, reinforcing the need for mitigation strategies and advanced treatment technologies to protect public health.

Spotlight on Drinking Water

Drinking water contamination is a major focus of the EPA’s findings. Industrial pollution, improper disposal, and legacy contamination all contribute to the problem, especially for communities near industrial facilities. Under the Toxic Substances Control Act (TSCA), the EPA must now propose actions to reduce these risks, which may include stricter regulations on production, use, and disposal.

What Should Water Utilities Do?

While the EPA hasn’t issued new regulations yet, water treatment facilities can take proactive steps:

1. Monitor and Test: Regularly test source water and finished drinking water for 1,4-dioxane. This helps track contamination and gauge centralized treatment effectiveness.
2. Upgrade Treatment Systems: Consider advanced oxidation processes (AOPs) or other proven technologies to reduce 1,4-dioxane levels.
3. Work with Local Industries: Partner with businesses to minimize discharges of 1,4-dioxane. This could involve reviewing permits and promoting cleaner practices.
4. Communicate with the Public: Keep residents informed about 1,4-dioxane levels, health risks, and steps being taken to ensure water safety. Transparency builds trust and compliance.

What Can Homeowners and Businesses Do?

This is a difficult contaminant to address at the POE/POU level. We know that AOP/UV is able to destabilize the compound and RO/GAC post-polishing can further address it. Since AOP/UV is not readily available in Residential and light-commercial settings, multiple-pass RO with multiple Carbon block stages is currently the next best thing.

Looking Ahead

The EPA’s new risk determination takes a cautious approach to 1,4-dioxane. However, future policy changes may affect how these risks are managed. For now, water utilities should stay informed, plan for potential regulations, and prioritize public health by addressing 1,4-dioxane contamination proactively.