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Consumer Products

Cleaning out a carcinogenic contaminant

Home and personal care firms have cut 1,4-dioxane levels in products to 1 ppm, but is that good enough?

by Craig Bettenhausen
January 22, 2025 | A version of this story appeared in Volume 103, Issue 2

 

Nobody is putting 1,4-dioxane into shampoo on purpose. It’s a carcinogenic impurity that forms in a side reaction during the production of ethoxylated alcohols, a class of surfactants used in consumer goods. And while that may make the chemical sound like a minor problem, getting it out of detergents and cosmetics is a major issue in the cleaning and personal care industries.

Chemical companies that make surfactants have been working to reduce 1,4-dioxane levels for a few years now. The driving force is a New York State law that prohibits the sale of cleaning and personal care products with a 1,4-dioxane concentration higher than 1 part per million (ppm) and cosmetics with a concentration above 10 ppm. The law went into effect at the end of 2022, and the last product waivers, which gave some consumer product makers time to sort out supply chains and sell off old stock, expire at the end of 2025.

Structure of 1,4-dioxane.

Companies say they will reach that goal, but they can’t relax yet. Regulations are still maturing, and some regions are considering a limit of 1 ppm in active ingredients rather than finished products. Because surfactants make up only 10–30% of common cleaning liquids such as shampoo and laundry detergent, that standard would be many times as strict.

As the law stands now, “if it’s on the shelf, it should be compliant,” says Marie Gargas, senior director of regulatory and international affairs at the American Cleaning Institute (ACI), an industry association. And because the New York State market is so big, the law has created a de facto national standard, she says. Moreover, California is working on regulations that also cap 1,4-dioxane concentrations at 1 ppm, starting with shampoo and dish soap.

And if the state laws weren’t enough, in November, the US Environmental Protection Agency stepped in with the finding that 1,4-dioxane presents an unreasonable risk to public health. Gargas says the EPA’s final risk evaluation for the chemicalestablishes the legal foundation for federal regulation under the Toxic Substances Control Act. The industry expects the EPA rule making to start as early as this fall.

Ethoxylated alcohol surfactants are in pretty much every home. Sulfated varieties like sodium laurel ether sulfate, which typically create the most 1,4 dioxane by-​product, provide the main cleaning power for countless laundry and dish detergents, hard-surface cleaners, shampoos, and toothpastes.

An important nuance in the EPA’s findings is that daily use of those products isn’t dangerous. “EPA finds that exposures to consumers and bystanders resulting from consumer use of products that contain 1,4-dioxane do not significantly contribute to the unreasonable risk,” the evaluation says.

The risk comes instead from drinking water that is contaminated with 1,4-dioxane, according to the EPA. Few municipal wastewater treatment systems can effectively remove or destroy 1,4-dioxane, so when cleaning products go down the drain, the chemical flows into waterways that feed drinking-water sources. Drinking-water providers similarly struggle to eliminate 1,4-dioxane.

The cleaning industry has long questioned what share of the blame it should shoulder—many of the hot spots for 1,4-dioxane contamination in groundwater are near industrial sites where the chemical was once used as a solvent or stabilizer. But companies and groups like the ACI have largely accepted the need to remove it from surfactants.

Other sources of 1,4-dioxane are beside the point for Thor-Erik Nyseth, sales and marketing director at the Norwegian surfactant maker Unger Fabrikker. It’s a pollutant, and if manufacturers can cut the amount that’s released into the environment, they should. “We don’t want people to get cancer,” Nyseth says. “Of course we want to reduce the 1,4-dioxane.”

Unger’s approach has been to add stripping steps—flash and steam distillation—to existing surfactant production lines. Both exploit 1,4-dioxane’s affinity for water as a lever to remove it. Vacuum stripping is another common choice for surfactant makers.

Retrofits like Unger’s get 1,4-dioxane levels below 5 ppm in the surfactant, says Neil Burns, an industry consultant and author of the popular blog Surfactants Monthly. That’s the current industry standard because it gives consumer goods makers enough room to formulate a final product that is below 1 ppm, he says.

Consumer product makers looking to avoid 1,4-dioxane can also switch to ingredients that are made in a way that doesn’t create it. Burns says he is seeing new cleaning and personal care products being formulated around historically secondary surfactants such as aminosurfactants and alkyl polyglucosides. New surfactants such as sophorolipids, rhamnolipids, and other biosurfactants have an opening as well, he says.

Bottles of laundry detergents sit on a grocery store shelf.
Credit: Craig Bettenhausen/C&EN
Most cleaning product makers in the US and Europe have already brought 1,4-dioxane levels in products down to 1 part per million or less.

Big multinational firms are unlikely to reformulate best-selling brands anytime soon, though. Even if their R&D teams identify molecules that can step in, it’s the start of a long process of scale-up, contract negotiation, and supply chain development. “It’s a huge problem to replace it in a short amount of time. To find replacement products . . . it’s difficult, very difficult,” Nyseth says.

One way or another, effectively all of the surfactants used in home and personal care products in the US today have low enough concentrations of 1,4-dioxane to comply with 1 ppm limits at the product level, Burns says. The surfactant maker Stepan, for example, said in an October investor call that it had upgraded all of its production sites by the end of 2023 to comply with New York’s limits.

“New York State alone would have been enough,” Burns says, “This EPA rule adds more fuel to the fire, but I’m not sure it’s going to change the trajectory, which is already towards hyperlow dioxane.”

The norm in the European Union is also 1 ppm or lower in the container on the grocery store shelf. “The EU has been ahead of the US on dioxane,” Burns says, because of high consumer awareness of the contaminant and strong competition among surfactant makers. Outside of a few products in small, regional markets, he says, “you’re not going to see the big multinationals or even the big private labels be significantly different from what’s the case right now in the US.”

Despite that head start, the industry is on high alert in the EU because of a proposal from Germany that would give Europe the strictest 1,4-dioxane regulation in the world: 1 ppm in active ingredients.

Industry executives aren’t sure that standard is realistic. Jan Ivar Ruud, Unger’s managing director, says the firm has been running pilot tests with additional stripping equipment. “What we see as doable is 3 ppm. That can be reached, but we doubt very much that we can reach 1 ppm,” he says.

Retrofits to most ethoxysulfation systems operating today would not be enough to reach 1 ppm in active ingredients, Burns says. Chemical makers would likely need to start with a brand-new reactor. One of Burns’s big clients is Ballestra, a maker of chemical production equipment that offers both retrofit equipment and new reactors. “It’s probably a lot better to start with a state-of-the-art sulfation reactor and then go downstream from there with your vacuum neutralization and additional stripping steps,” he says.

If it’s on the shelf, it should be compliant.
Marie Gargas, senior director of regulatory and international affairs, American Cleaning Institute

New equipment and additional steps add to the cost of any manufacturing process. Nyseth says Unger is fortunate to have access to low-carbon geothermal energy because, otherwise, getting rid of 1,4 dioxane would also increase the greenhouse gas footprint of its products—not the direction Unger wants to go.

Regulating 1,4-dioxane in consumer products challenges another of the cleaning industry’s current sustainability trends, ACI’s Gargas says: the move to concentrated formulations. Most major brands have introduced laundry and dish concentrates in recent years because cutting the water content reduces the amounts of fuel spent shipping the product and the plastic used to contain it. But if the active ingredients are more concentrated, so is the 1,4-dioxane.

Gargas has worked mostly on 1,4-dioxane policy since she started at ACI about a year ago. Member companies would like to expand their lines of concentrates, as well as concentrated refills, into more types of cleaners and into lower-priced brands. In New York and California, she says, her advocacy is focused on making sure new rules don’t halt that progress.

Regulating contaminants at the household-use level—meaning the rules would look at the concentration of 1,4-dioxane in the product plus the average amount of water consumers use it with—could be the most flexible approach. A dish soap four times as strong as a standard formulation could be compliant at 4 ppm, for example.

At the federal level, ACI doesn’t dispute the EPA’s interest in regulating 1,4-dioxane. But Gargas says the agency is using outdated data sets, subpar models for the flow of the contaminant from drains to the environment, and “an approach to the mode of action for carcinogenicity that remains out of step with other regulatory authorities around the globe.”

Those details will affect the regulations the agency expects to propose later this year, and Gargas says she is “continuing to have the conversations, not just on the work that’s been done and the work that’s ongoing but on how the incoming administration is going to look as a whole at chemicals management.”

In Europe, the industry is sending operational data and meeting with regulators in hopes of landing on a standard of 1 ppm for finished consumer products, Nyseth says. “The plan is that you have this hearing now, and you will get some answers in October, and then you have a couple of years to adapt to the new regulations.”

Chemical makers and their customers in the cleaning and personal care industries have room to breathe now that their supply chain meets the current 1,4-dioxane standards. That doesn’t mean they can get complacent. “For the big soapers, this is a huge business. An enormous business, actually,” Ruud says, “and it will have extremely big consequences.”

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