1,4-dioxane
A contaminant created during manufacturing rather than added, so it never appears on an ingredient list. It forms when ingredients are processed with ethylene oxide, which is common in anything that foams. A label cannot tell you it is there.
Definition and health context from EPA.
We checked 3,681 products and found 1,4-dioxane reported or likely in 1 of them.
Where 1,4-dioxane turns up
Categories we grade, worst first, as a share of what we scored in each.
| Category | Flagged | Scored | Share |
|---|---|---|---|
| Cosmetics | 5 | 8 | 63% |
| Shampoo | 118 | 191 | 62% |
| Body Wash | 21 | 35 | 60% |
| Conditioner | 47 | 102 | 46% |
| Makeup | 22 | 54 | 41% |
| Foundation | 8 | 20 | 40% |
| Lip Gloss | 6 | 15 | 40% |
| Waterproof Mascara | 16 | 47 | 34% |
| Lip Balm | 18 | 55 | 33% |
| Foundation | 5 | 15 | 33% |
| Moisturizer | 5 | 15 | 33% |
| Concealer | 4 | 15 | 27% |
| Beauty Primers & Setting Sprays | 3 | 15 | 20% |
| Eyeliner | 3 | 15 | 20% |
Where we found real evidence
Reported or likely, lowest scoring first. Not plausibility.
1,4-dioxane is a known manufacturing byproduct in some ethoxylated surfactants commonly used in shampoos. The FDA does not regulate cosmetics for this contaminant, though it appears in trace amounts in many mainstream shampoos. OUAI does not publicly disclose
What to buy instead
Highest scoring products with no flag for it, in the categories where it is worst.
How to spot 1,4-dioxane yourself
What is actually visible to someone holding the product, which for most of these is the only check available.
- It is never on a label, because it is created during manufacturing rather than added.
- Sodium laureth sulfate, and anything else with "laureth", "-eth-" or PEG in the name.
- Polysorbates and ingredients ending in "-oxynol".
- A rule of thumb that is crude but works: if it foams a lot and it is cheap, the risk is higher.
Where it turns up outside our data
Anything that lathers. Shampoo, body wash, bubble bath, dish soap and laundry detergent, plus some baby products.
What the rules actually say
New York State set the first consumer limits in the country, taking effect from 2023 and tightening in 2024, at parts per million in cosmetics, personal care and cleaning products. There is no federal limit. The EPA classifies it as likely to be carcinogenic to humans, and it is also a common groundwater contaminant.
Read alongside EPA and our state by state guide to PFAS bans.
Common questions
What is 1,4-dioxane?
A contaminant created during manufacturing rather than added, so it never appears on an ingredient list. It forms when ingredients are processed with ethylene oxide, which is common in anything that foams. A label cannot tell you it is there.
Which products contain 1,4-dioxane?
Of the 3,681 products we have graded, 319 are flagged for it and 1 on reported or likely evidence rather than plausibility. Cosmetics is the worst category at 63% of what we scored there.
Is 1,4-dioxane in cosmetics?
More than in anything else we grade. 5 of the 8 cosmetics we scored carry a flag for it, which is 63%. The full breakdown per product is on each product page.
What can I buy instead?
In the categories where it turns up most, the highest scoring products with no flag for it are bareMinerals bareMinerals Mineral Makeup at 100, Ilia Beauty Ilia Beauty Clean Makeup at 100, RMS Beauty RMS Beauty Organic Makeup at 100. Every one of those was graded on the same rubric as the products above.
How can I tell if a product has 1,4-dioxane in it?
It is never on a label, because it is created during manufacturing rather than added. Sodium laureth sulfate, and anything else with "laureth", "-eth-" or PEG in the name. Polysorbates and ingredients ending in "-oxynol". It turns up in anything that lathers. Shampoo, body wash, bubble bath, dish soap and laundry detergent, plus some baby products.
Is 1,4-dioxane banned?
New York State set the first consumer limits in the country, taking effect from 2023 and tightening in 2024, at parts per million in cosmetics, personal care and cleaning products. There is no federal limit. The EPA classifies it as likely to be carcinogenic to humans, and it is also a common groundwater contaminant.
How do you know?
We do not lab test. Every grade here is built from published ingredient lists, materials, certifications, brand disclosures, recalls and third party lab results where those already exist. Where a product has been independently tested we use that result and say so, and where a brand publishes nothing we score the silence rather than guessing.
9% of everything we grade carries a flag for 1,4-dioxane. See every hazard we track or browse the full products list.