Frequently Asked Questions About 1,4-Dioxane, Health and Water Treatment

1,4-Dioxane is a synthetic chemical (not naturally found in the environment) that has been widely used as a solvent and a stabilizer for chlorinated solvents in various industries. Additionally, it is a by-product in the manufacture of detergents, shampoos, and cosmetics. This chemical is highly water soluble and resists natural biodegradation. It can enter surface water and groundwater through numerous pathways, thereby contaminating our drinking water resources. According to the monitoring data obtained by the EPA Third Unregulated Contaminant Monitoring Rule (UCMR3), there is a widespread occurrence of 1,4- dioxane in US drinking water. Moreover, people can be exposed to 1,4-dioxane by using detergents, shampoos, and shower gels through skin absorption.

Pathways of 1,4-dioxane entering drinking water resources:

1. Landfill leachates into groundwater.
2. Industrial waste runoff into surface water.
3. Wastewater treatment discharge.
4. Household & personal care products in domestic waste.

The health risks associated with 1,4-dioxane have been highlighted through animal studies, which show that long-term exposure through drinking water leads to organ damage, including cancers of liver and kidney. While it is crucial to note that effects observed in animals may not directly translate to humans, these findings suggest that 1,4-dioxane is a likely human carcinogen by the exposure route of drinking water. The risk to human health is amplified by the inability of conventional water treatment processes to effectively remove 1,4-dioxane. Therefore, limiting human exposure to this chemical is advisable to reduce potential public health risks.

Currently there is no federal regulation for 1,4-dioxane in the drinking water. Some states have established standards and guidance values for drinking water and groundwater. You need to first find out whether 1,4-dioxane is included within the list of regulated compounds for drinking water in your state. Find out here for State Regulations, Policies, and Guidance for 1,4-Dioxane. If it is regulated, you can find information about 1,4-dioxane concentration through your state’s official water quality report. If it is not regulated or you use a private well, the best way to know the 1,4-dioxane level in your drinking water is by reaching out to a certified laboratory to get the water tested. If your local labs are not able to provide testing for 1,4-dioxane, there is currently no practical way to measure 1,4-dioxane in your drinking water.

Conventional water treatment process

1,4-Dioxane is difficult to be removed using conventional water treatment processes such as adsorption, filtration and reverse osmosis. Due to its small size and neutral charge, it does not adsorb onto activated carbon or get filtered out. Reverse osmosis offers a better removal, however, 1,4-dioxane can pass through the RO membrane without being removed.

Advanced treatment process

First implied for drinking water treatment in the 1980s, advanced oxidation process (AOP) has been proved to be a robust and powerful water treatment technology. AOP generates highly oxidative free radicals (especially, hydroxyl radical) from chemical precursors (for example, hydrogen peroxide) to aggressively destroy 1,4-dioxane. Unlike other treatment methods, AOP can completely oxidize 1,4- dioxane producing biodegradable intermediates and finally into water and carbon dioxide.

Conventional water treatment process

Project 1:

We are actively researching 1,4-dioxane to understand its health effects based on animal studies. Much of this research focuses on how 1,4-dioxane in drinking water might cause tissue damage (such as liver toxicities or cancer) in laboratory animals. These studies are crucial for determining the mechanisms by which 1,4-dioxane causes adverse health effects. In addition, we are examining the carcinogenic effects of mixtures of 1,4-dioxane and its frequently found co-contaminants trichloroethylene (TCE) and 1,1-dichloroethane (1,1-DCA). This project will guide the development of safe environmental and water standards. Keep in mind that these are animal studies, and we are still exploring what our findings mean for human health.

Project 2:

We are currently using a highly sensitive method (the same as used by the Center for Disease Control and Prevention (CDC)) to assess human exposure to 1,4-dioxane and co-contaminants from drinking water in a population of adults in a region with high contamination potential (Long Island, NY). and evaluate the relationship between environmental and biological exposure indicators. This method involves the use of gas chromatoraphy-mass spectrometry (GC-MS) and can detect concentrations of 1,4-dioxane as low as 0.005 parts per billion (ppb). Our project is also evaluating the relationship between 1,4-dioxane exposure and the plasma metabolome, with a focus of biological markers of liver toxicity and carcinogenicity. The existing drinking water monitoring data obtained by the EPA was from 2013 to 2015, which was outdated and had limited sampling locations on Long Island. Our project aims to advance this knowledge and provide up-to-date information to the community on the 1,4-dioxane concentrations from drinking water sources and explore potential human health outcomes from 1,4- dioxane exposure.

Project 3:

We are developing a low-cost biosensor for rapid detection of 1,4 Dioxane. These sensors could be inexpensively deployed in private wells or water treatment facilities to provide real-time information on 1,4-dioxane concentrations in drinking water.

Project 4:

We are developing modular, cost-effective water treatment system for water suppliers or household application, such as:

• Portable AOP System: We have developed a portable electrochemical reactor for continuous hydrogen peroxide production. It will be coupled with effective catalysts to activate hydrogen peroxide and produce sufficient radicals for 1,4-dioxane degradation.
• Electrooxidation System: We are developing an electrified flow reactor equipped with low-cost electrodes. The electrode material could directly produce radicals without chemical addition under the electric current that subsequently destroys 1,4-dioxane.

These technologies are still under development, and thus, not commercially available yet, but the goal is to make the cost similar to current at-home treatment technologies.

• EPA Fact Sheet - 1,4-dioxane (2014)
• State Regulations, Policies, and Guidance for 1,4-Dioxane
• CA Water Boards Groundwater Fact Sheet 1,4 Dioxane (2019)
• ATSDR ToxFAQS for 1,4-Dioxane (2015)
• FL Health 1,4-Dioxane General Facts (2021)
• CA OEHHA 1,4-Dioxane (2023)
• MI Understanding Risk: What’s Behind the Numbers 1,4-Dioxane (2017)
• NY State Human Health Fact Sheet: 1,4-Dioxane (2021)
• Citizens Campaign: Shopping Safe: The 2018 Consumer Shopping Guide Protecting Your Household From 1,4- Dioxane Exposure