1,4-Dioxane in Laundry Detergent: What the Testing Found

In 2019 the Citizens Campaign for the Environment pulled five of the best-selling laundry detergents in America off a shelf and sent them to a lab. Tide Original. Persil. Tide Simply Oxi. Gain Original. And Dreft Stage 1, the one sold for newborns.

Every sample came back carrying 1,4-dioxane, which the EPA calls a likely human carcinogen. The results ran from 6.1 parts per million up to 14.

They ran the same test on the same products in early 2024. This time every one came back under 1 ppm.

So this is a story about something getting fixed, which makes it rarer than most ingredient scares. It’s also a story about how little the bottle was ever going to tell you, and that part hasn’t changed at all.

Why it’s in there when nobody put it in there

1,4-dioxane isn’t an ingredient. No one adds it, no brand wants it, and it has no job to do in your wash.

It’s a leftover. Making the foaming agents in detergent gentler and more water-soluble takes a manufacturing step called ethoxylation, and that reaction can leave a little 1,4-dioxane behind in the finished batch. How much depends entirely on how carefully the maker cleans up afterward. It can be stripped out. Plenty of manufacturers do exactly that.

The ingredients that bring the risk with them are easy to recognize once you’ve seen the list. Sodium laureth sulfate is the big one, and it sits on a huge share of conventional detergent labels. Laureth-6 and laureth-7, C12-16 pareth, and anything with PEG in its name come out of the same kind of process.

Here’s the part that matters. Those are all real ingredients, printed right there on the bottle, doing real work. The leftover riding along with them appears nowhere, because a factory residue isn’t an ingredient and no US labeling rule requires anyone to print it.

Which meant that for years, a clean batch and a dirty batch looked identical from the outside.

What actually moved the numbers

New York wrote a law. In 2019 the state set hard caps on how much 1,4-dioxane a household cleaning product could contain: 2 ppm from the end of 2022, tightening to 1 ppm at the start of 2024.

We went through that rule in more detail in our piece on PEG-100 stearate, since it reaches cosmetics too. For laundry, the effect was blunt. Detergents over the cap couldn’t be sold in New York, and running two versions of a national product, one clean for one state and one dirty for everywhere else, is an expensive way to make a mess for yourself. So the reformulating happened across the board.

That’s why the 2024 retest looks the way it does. The law worked, quietly, on products most people had already decided were beyond saving.

And a bottle of Tide bought this week is a different product from the one your mom bought in 2019. Nothing on the front announces that.

The part I don’t want to oversell

Don’t read the test results as an all-clear on conventional detergent. One problem got solved. The others are exactly where they were.

The word “fragrance” still sits on most of those same labels, still standing in for a list of ingredients nobody has to disclose. Optical brighteners are still in there, still designed to stay on your clothes rather than rinse away. Those are separate arguments with separate evidence, and we’ve written both of them up: what’s hiding behind “fragrance” and why optical brighteners are in your detergent at all.

There’s also a piece of this that a reformulation can’t touch. 1,4-dioxane doesn’t break down readily once it’s in water, and it isn’t removed by conventional water treatment. Lower amounts going down millions of drains is a real improvement. It isn’t the same as the problem being over.

What I’d actually do about it

Not panic-buy on this one. If you’ve got half a jug of Tide under the sink, finishing it is fine, and throwing it out to feel safer would be a waste of a jug of detergent.

If you’d rather skip the whole category of risk, the shortcut is the ingredient list rather than the marketing. Detergents built on plant-based enzymes don’t need ethoxylated foaming agents in the first place, so there’s no reaction to leave anything behind. Dirty Labs is the clearest example, and it’s the one I hand people who think switching means accepting a worse clean.

The other route is to let a certification do the reading for you. MADE SAFE screens a full ingredient list against contaminants, which is the specific thing at stake here. Meliora and Branch Basics both hold it. Blueland carries EPA Safer Choice on top of a formula that skips the risky chemistry anyway.

Any of those gets you out of the question entirely, which beats trying to guess a manufacturing standard from a label that was never going to mention it.

Frequently asked questions

Is 1,4-dioxane still in laundry detergent?

In much smaller amounts than five years ago. Lab testing of five best-selling brands in early 2024 found all of them under 1 part per million, down from a range of 6.1 to 14 ppm when the same products were tested in 2019. New York’s limits are what drove the change, and because national brands didn’t want separate formulas per state, the cleanup went nationwide.

Which detergent ingredients create 1,4-dioxane?

Anything made by ethoxylation. Sodium laureth sulfate is the most common one in laundry, along with laureth-6, laureth-7, C12-16 pareth, and ingredients whose names start with PEG. It’s worth being precise: those ingredients don’t contain 1,4-dioxane by definition. They can carry it as a leftover if the manufacturer didn’t strip it out.

Does 1,4-dioxane stay on your clothes after washing?

It’s water-soluble and rinses out with the wash water, so it isn’t the residue problem that optical brighteners are. The bigger exposure route is drinking water, because it resists breaking down and standard treatment doesn’t remove it.

Is 1,4-dioxane banned in the US?

No federal ban exists. New York set the first state limits on how much can be in a consumer product, and those caps are what changed the market. The EPA classifies it as likely to cause cancer in humans but hasn’t restricted it in consumer goods nationally.

Related reading

For the brands that clear this and everything else we check, see the best non-toxic laundry detergents. The rest of this series pulls apart what’s on a detergent label: optical brighteners, the fragrance loophole, and what “non-toxic” is actually claiming. Our non-toxic cleaning guide covers the whole cupboard, and every brand above has a scored profile in the brand directory.

Sources: Citizens Campaign for the Environment, Laundry detergent samples show lower amount of 1,4-dioxane in household products, February 2024. New York State Department of Environmental Conservation, 1,4-dioxane limits for household cleansing, personal care and cosmetic products. US Environmental Protection Agency, 1,4-Dioxane technical fact sheet.