Q&A: What is 1,4-dioxane, is it safe to drink and how do you get rid of it?

People wonder about the health risks they face – from driving on Interstate 4, to sun exposure, to consuming alcohol, to eating bacon and more – but drinking tap water usually isn’t one of them.

Many residents of Seminole County, however, are now wondering whether what comes from their faucets is safe, following the Orlando Sentinel’s recent Toxic Secret series that for the first time comprehensively revealed how an industrial chemical federally listed as likely to cause cancer has infiltrated their water for years or even decades.

The chemical, 1,4-dioxane, is poorly researched for health risks and has been linked to pollution from a shuttered factory in Lake Mary.

Here are answers to questions from people living in Sanford, Lake Mary and west Seminole County.

What is 1,4-dioxane?

It is a synthetic industrial chemical that dissolves completely in water. It is used and occurs in an extraordinary variety of processes and products, including textile production, paint stripping, coatings and some consumer goods such as cosmetics and soaps.

In its pure form, it smells faintly sweet and similar to ether. It is colorless.

In Seminole County, extensive ground and water pollution containing 1,4-dioxane has been documented in the vicinity of a shuttered telephone systems factory in Lake Mary. Factory owners have denied liability for any migration of the chemical to water wells of Lake Mary, Sanford and west Seminole County.

Can I see, smell or taste 1,4-dioxane in my tap water?

That would not be possible in the minute concentrations measured in Sanford and west Seminole, and previously in Lake Mary, which in 2021 started up a treatment plant designed specifically to remove the chemical.

Concentrations of the chemical in the tap water of the two cities and county have been measured in parts per billion, or ppb, ranging from about 0.2 ppb to about 1.5 ppb. The state’s health advisory limit is 0.35 parts per billion. That equates to an 8 ounce cup of the chemical mixed into 150 million gallons of water.

What do Sanford, Lake Mary and Seminole County say about the health risk of 1,4-dioxane in their water?

Sanford and Seminole County say their water is safe based on the health-advisory limit set by the Florida Department of Health and the U.S. Environmental Protection Agency of 0.35 ppb.

When 1,4-dioxane was first found in Sanford and in west Seminole County from 2013 to 2015, their utilities reduced use of wells that were the most contaminated with the chemical, lowering concentrations to about 0.2 ppb.

Lake Mary’s water consistently contained more than 1 ppb until 2021 when the city started up its advanced treatment plant.

Why didn’t Lake Mary, Sanford and Seminole County tell anyone about 1,4-dioxane in their water?

All three governments said they complied with federal regulations when they first detected the chemical.

They added statements about the chemical to their annual water reports in 2015 and 2016 that were brief, largely obscure and lacking context, such as the state and federal health advisory level for 1,4-dioxane.

No other public statements were made after that.

Read Orlando Sentinel’s ‘Toxic Secret’ water contamination series for free here

What can any customer of a private or public utility do to learn if there are potentially harmful chemicals in their water?

The U.S. EPA requires utilities to state in their annual water reports if they have detected – whether above or below allowed concentrations – any of 90 contaminants potentially found in drinking water. That’s a fraction of the total potential number of contaminants from pesticides, factories, petroleum, sewage and other sources.

The best option for utility customers may be to reach out directly to their utilities and ask if they know of any contaminants detected in water within the past decade and not included in their annual reports.

In addition, Seminole County commissioners on July 25 shared plans to increase testing and create an online dashboard with current levels of various contaminants, including 1,4-dioxane, at its wells and treatment plants.

In the meantime, a PowerPoint on the county’s 1,4-dioxane page shares recent measurements.

How can I test for 1,4-dioxane in my tap water?

To measure the chemical in household drinking water, there are a number of certified commercial analytical laboratories that can test for 1,4-dioxane, including several that will ship testing equipment to your home, allowing you to collect a sample and send it back for analysis. These tests range in sensitivity.

Seminole commissioners urge EPA action on 1,4-dioxane, ‘long, hard look’ at pollution’s source

What if I have a private well for my home?

The Orlando Sentinel had reached out to the Florida Department of Health for guidance on this question but the department has not responded to this or other inquiries on the topic.

The department provides private well information at FloridaHealth.gov/Wellstest

How can 1,4-dioxane be removed?

Typical water treatment methods can’t get rid of 1,4-dioxane, which is notoriously hard to treat.

The most effective treatment available is a process called advanced oxidation, which destroys all but trace amounts of the chemical often by using hydrogen peroxide and ultraviolet light. Of note, the plant Lake Mary installed in 2021 uses this method.

Home systems that use reverse osmosis can remove most of the chemical from drinking water; because of its characteristics, some 1,4-dioxane can slip through filtration membranes of reverse osmosis.

Experts agree that it is not practical to try to treat water for 1,4-dioxane contamination house-by-house, and a water treatment plant is the more efficient option.

Is water with 1,4-dioxane safe to drink?

Researchers are generally in agreement that the risk posed by 1,4-dioxane depends on the amount, the length and route of exposure.

Animal studies suggest that exposure to a large amount of the chemical at once, through drinking or inhaling it, can have toxic liver and kidney effects.

Other studies have exposed rodents to the chemical for two years via drinking water. Those studies suggest that lower doses, over long periods of time, can also have toxic effects, leading to liver cancer, and, less commonly, kidney, peritoneum, mammary and nasal cavity cancers.

Orlando Sentinel holding community forum on Seminole County water

In 2013, the EPA estimated that if someone drank water with a 1,4-dioxane concentration of 0.35 parts per billion for 70 years, this would increase their risk of cancer by less than 1 in 1 million.

There haven’t been any studies on the impacts of long-term oral exposure in humans, however.

It’s likely that the health impacts of 1,4-dioxane vary based on what other risk factors or chemicals a person is exposed to. The American Cancer Society notes online that even if a substance is a probable carcinogen, carcinogens don’t cause cancer in every circumstance, and this “does not necessarily mean that it can or should be avoided at all costs.”

An ongoing study at Yale University may bring answers but won’t wrap up until at least 2027. The study’s leader has previously told the Orlando Sentinel he tries to avoid drinking water with dioxane or any other chemicals.

Should certain populations take extra caution to avoid chemicals like 1,4-dioxane in tap water?

There isn’t enough research to say, but it’s possible that some people will be more vulnerable to the chemical’s impacts.

The EPA states online that because children are still developing, they may be more sensitive to some drinking water contaminants, such as PFAs. They also drink more relative to their body weight than adults.

However, there have been no studies on the effects of this chemical in children or pregnant women. It’s also possible that people with certain conditions are more sensitive to this chemical, as is the case with several other environmental contaminants.

However, there’s not enough research to know for sure, said American Cancer Society scientific director Leticia Noguiera.

Can I find out if my illness was caused by 1,4-dioxane?

At the moment, no. There’s often no way to link an illness back to a specific contaminant, even if there is proof of exposure.

Many illnesses, including cancer, are believed to develop as a result of several different factors, not just one. In addition, while it may be clear that you’ve been exposed to 1,4-dioxane currently in your water, there is no way to determine if you’ve been exposed to 1,4-dioxane in the past.

Though 1,4-dioxane can linger for decades if not removed from a water source, it leaves the human body quickly and there are no currently known biomarkers associated with a past exposure. Effects can take years to develop, if any occur.

What is the US Environmental Protection Agency doing about this?

The EPA regulates over 90 contaminants in drinking water, requiring utilities to test for them and share their results publicly. 1,4-dioxane is not one of them, but it may soon be.

In 2016, the EPA announced plans to review 1,4-dioxane alongside nine other chemicals under an expansion of the 1976 Toxic Substances Control Act that gave it more power to regulate chemicals than ever before.

In 2020, the agency released a risk assessment that focused mostly on occupational exposure to the chemical, and found that the chemical posed unreasonable risks to workers, but not the general population. That risk assessment, however, failed to consider many of the ways people are exposed to 1,4-dioxane in their everyday lives.

In July, the agency released a draft of a supplement to the original 2020 analysis, and a draft of a new risk evaluation of the chemical. The new draft considers dioxane exposures from air, drinking water and consumer products that were excluded from the original evaluation. The draft concludes that this chemical puts human health at risk.

“EPA proposes to determine that 1,4-dioxane, as a whole chemical substance, presents unreasonable risk to human health,” the EPA states.

These documents are preliminary. They will undergo a peer review and public comment process until September, which may alter their conclusions. If the determination is finalized that 1,4-dioxane presents an unreasonable risk, the agency will have a year to propose new rules to mitigate those risks, and two years to issue a final rule, according to an overview of the risk management process.

Sentinel reporters Kevin Spear and Martin Comas contributed to this report. Caroline Catherman can be reached at ccatherman@orlandosentinel.com or @CECatherman Twitter.