Shampoos and hair care products (1,4-dioxane, preservatives)
Manufacturing contaminant and preservatives
๐ด The exposure is real and common, but no serious study has measured its effect on human fertility. It remains unknown.
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In brief
1,4-dioxane in shampoo: this page reviews Shampoos and hair care products (1,4-dioxane, preservatives) (Manufacturing contaminant and preservatives) โ documented mechanism, everyday exposure situations and possible alternatives. Level of evidence: Not studied.
- Where it's found
- 1,4-dioxane is a manufacturing byproduct (from ethoxylation), not an intentionally added ingredient โ detectable via mentions of "PEG," "polyethylene glycol," "-eth-," or "-oxynol-" in the ingredient list. Also of note: preservatives that release formaldehyde (quaternium-15) and allergens such as MIT/CMIT (methylisothiazolinone).
- Suspected mechanism
- A 2017 Hong Kong Consumer Council study (60 models tested) detected 1,4-dioxane in 60 to 70% of shampoos, and allergenic MIT/CMIT preservatives in about 20%. 1,4-dioxane is classified as a probable carcinogen by the EPA (US Environmental Protection Agency), with documented liver and kidney effects at high doses. No study specifically linking these substances to human fertility has been identified to date: the documented risk lies elsewhere (carcinogenicity, skin allergy), not reproduction.
- Suggested alternative
- Avoid products listing several "PEG"/"-eth-" ingredients near the top of the list; favor shampoos with short ingredient lists.
- Source
- Hong Kong Consumer Council 2017; EPA (1,4-dioxane classification); ATSDR (Agency for Toxic Substances and Disease Registry, US); Campaign for Safe Cosmetics.
Frequently asked questions
Shampoos and hair care products (1,4-dioxane, preservatives): how is it linked to infertility?
A 2017 Hong Kong Consumer Council study (60 models tested) detected 1,4-dioxane in 60 to 70% of shampoos, and allergenic MIT/CMIT preservatives in about 20%. 1,4-dioxane is classified as a probable carcinogen by the EPA (US Environmental Protection Agency), with documented liver and kidney effects at high doses. No study specifically linking these substances to human fertility has been identified to date: the documented risk lies elsewhere (carcinogenicity, skin allergy), not reproduction.
Where is Shampoos and hair care products (1,4-dioxane, preservatives) found in everyday life?
1,4-dioxane is a manufacturing byproduct (from ethoxylation), not an intentionally added ingredient โ detectable via mentions of "PEG," "polyethylene glycol," "-eth-," or "-oxynol-" in the ingredient list. Also of note: preservatives that release formaldehyde (quaternium-15) and allergens such as MIT/CMIT (methylisothiazolinone).
How can exposure to Shampoos and hair care products (1,4-dioxane, preservatives) be reduced?
Avoid products listing several "PEG"/"-eth-" ingredients near the top of the list; favor shampoos with short ingredient lists.
What is the level of evidence for Shampoos and hair care products (1,4-dioxane, preservatives)?
Not studied. The exposure is real and common, but no serious study has measured its effect on human fertility. It remains unknown.
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Related factors
Including a factor does not mean it causes infertility: it is simply worth monitoring, depending on its level of evidence.
Content last updated: September 14, 2026