What Is 1,4-Dioxane?  (And Why You Won’t See It on Labels)

When you’re picking personal care products, you probably try to make safe, gentle choices. Especially if you’re reaching for clean or natural brands. 

But there’s a hidden contaminant you need to know about.

What is 1,4-dioxane and why should you care if it’s hiding in your cosmetics or laundry detergent? This hidden chemical can sneak into products, even when the label may look pretty good. 

The more I dug into it, the more I realized how widespread and concerning 1,4-dioxane really is. Knowing this will help you protect your health and make smarter choices for you and your family.

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What is 1,4-Dioxane?

You won’t find 1,4-Dioxane listed on any product label. But it may still be hiding in your shampoo, baby wash, or even products labeled as natural or organic. 

That’s because it’s not an ingredient companies add on purpose.  It’s a chemical byproduct that forms during manufacturing. 

Most people have never heard of it, but it’s quite common and potentially harmful.

How 1,4-dioxane ends up in products can be a little hard to grasp at first.

Hopefully this analogy can help:

Imagine you have a wool sweater with a tough stain. Regular washing is too harsh and will ruin it. So you take it to the dry cleaner.

The dry cleaner uses special chemicals that work on this fabric. They seemingly work great… the stain comes out, and the sweater isn’t damaged.

But those cleaning chemicals leave trace residue in the fibers. You can’t see it or smell it, but it’s there.

A good dry cleaner will do extra rinses to remove that residue. But if they skip that step (because it costs time and money), the residue stays in your sweater.

And you take it home and wear it against your skin, not knowing it’s there.

That’s kind of what happens with 1,4-dioxane. Companies use ethoxylation to make harsh cleansing ingredients gentler. And it works. The product is gentler.

But the process leaves 1,4-dioxane behind as trace contamination.

Of course, they could remove it with extra purification steps. But most don’t because it’s not required and costs money. So it stays in the product and ends up on your skin.

(Just an aside: this is why I don’t have my clothes or bedding dry cleaned.)

How 1,4-Dioxane Forms

It’s most commonly created when ethoxylation is used to make harsh ingredients milder.

Here’s how that works. Manufacturers start with ingredients that would be too harsh for your skin. Often it’s cleansers or detergents.

To make them gentler, they use a chemical process called ethoxylation. This process adds ethylene oxide to soften the ingredients.

But when they use ethylene oxide, 1,4-dioxane forms as a side effect. It’s unintentional, but it happens.

That’s why it shows up in products made with things like sodium laureth sulfate, PEG compounds, and polysorbates.

The ingredient itself (e.g., sodium laureth sulfate) gets listed on the label. But the 1,4-dioxane contamination doesn’t. It stays invisible to you.

Why 1,4-Dioxane Isn’t on Labels

Companies aren’t required to disclose it.

Why, you ask? Simply because 1,4 dioxane is a byproduct and not an intentionally added ingredient.

Under U.S. law, only ingredients that are deliberately added to products have to be listed. Byproducts, contaminants, and trace impurities don’t have to appear anywhere on the label.

I find this to be so maddening.

So 1,4-dioxane can contaminate a product, and you’d have no way to know by just looking for it on the ingredient list.

Which makes it especially tricky to avoid, unless you know exactly what to look for.

Why Should I Avoid 1,4-Dixoane?

There are many reasons we should avoid 1,4-dioxane. Here are a few:

Classified as a Probable Human Carcinogen

The EPA classifies 1,4-dioxane as “likely to be carcinogenic to humans” based on animal studies and other evidence.

The International Agency for Research on Cancer (IARC) puts it in Group 2B. That means it’s possibly carcinogenic to humans.

These aren’t fringe opinions. They’re conclusions from regulatory and scientific bodies that study chemicals and cancer risk.

Found to Cause Cancer and Organ Damage in Animal Studies

Long-term exposure has been linked to liver and kidney tumors in animal studies.

Rats and mice exposed to 1,4-dioxane over time developed cancer at higher rates than unexposed animals.

Can Get Into Your Body Multiple Ways

1,4-dioxane can get into your body by:

• penetrating the skin
• being inhaled during use
• being ingested in trace amounts through personal care products.

It isn’t just sitting on the surface. It gets absorbed.

Passes From Mother to Baby During Pregnancy

During pregnancy, 1,4-dioxane can pass from mother to baby.

Babies’ and young children’s bodies are still developing. Therefore, they’re more vulnerable to chemical exposures.

This is particularly concerning given what we know about 1,4-dioxane’s potential effects.

Found in Many Products Marketed as “Gentle”

This is what really gets me. 1,4-dioxane shows up in products specifically marketed as gentle, natural, or even for sensitive skin.

Why? Because those products often use ethoxylated ingredients to be milder and less irritating. And ethoxylation creates 1,4-dioxane as a side effect. (That dry cleaning story again.)

So the very process used to make products gentler can be contaminating them with a probable carcinogen.

The Regulatory Loophole

1,4-dioxane has been found in shampoos, baby wash, body wash, and even household cleaners.

The FDA has acknowledged the concern. In fact, since the 1980s, the FDA has recommended that manufacturers remove 1,4-dioxane from their products. But here’s the problem: it’s voluntary.

I know, right? 🙄

The FDA doesn’t currently require its removal. Instead, manufacturers are simply encouraged to take steps to reduce contamination.

That means whether or not a company removes 1,4-dioxane is entirely up to them. Which makes finding companies who are transparent about their ingredients so important.

Some states are taking stronger action.

• California has listed 1,4-dioxane under Proposition 65 as a chemical known to cause cancer.
• New York passed a law limiting 1,4-dioxane in products distributed or sold in the state. Personal care products and household cleaners can’t exceed 1 ppm, while cosmetics can’t exceed 10 ppm.

But at the federal level, it’s still legal. And it’s still very common.

How Common Is This Problem?

It’s very common. Studies have found 1,4-dioxane in a wide range of products.

According to the EWG, 1-4,dioxane is found in 28% of personal care products. Anti-aging products and baby products had some of the highest levels of 1,4-dioxane.

Even products labeled “organic” or “natural” have tested positive for 1,4-dioxane.

FDA analysis cosmetic raw materials and finished products found:

• Ethoxylated raw materials contained levels up to 1,410 ppm
• Finished cosmetic products contained levels up to 279 ppm
• Some children’s shampoos exceeded 85 ppm

A 2018-2019 study by the Citizens Campaign for the Environment tested 80 household products. They found 1,4-dioxane in 65 of them. That’s 81%.

The highest level detected was 17,000 parts per billion. Some laundry detergents contained levels over 50,000 parts per billion.

The products with concerning levels included well-known brands like Tide (14,000 ppb), Dreft baby detergent (10,000 ppb), and Pantene shampoo (5,500 ppb).

Let’s put this in perspective. The EPA considers just 0.35 parts per billion in drinking water a 1-in-a-million cancer risk over a lifetime. These products had levels tens of thousands of times higher.

The Bottom Line

1,4-Dioxane is a toxic chemical byproduct that forms during manufacturing. It’s in many personal care, cleaning, and household products.

It’s classified as a probable human carcinogen. It can penetrate your skin. It’s found in products marketed as gentle and even natural. And companies don’t have to tell you it’s there.

You can’t spot it by reading the ingredient list because it’s not listed. But you can learn to recognize the ingredients that are likely contaminated with it.

And once you know where it’s hiding, you can start making different choices.