Chapter 1: Anionic surfactants
Sodium C14-16 olefin sulfonate (AOS)
- Contaminant risk
The worst fact: Japan's government classes it as suspected of damaging fertility or the unborn child.
Why brands use it: it cleans and foams like a sulfate, but lets the label say "sulfate-free".
Take care if: you have sensitive skin. US safety reviewers limit it to 2% in products that stay on the skin.
Comes from: petroleum: made from ethylene.
Myth check: "sulfate-free means gentle": no. AOS is a sulfonate rather than a sulfate, but it's still a strong cleaner and can irritate.
Contaminants: sultones. These are powerful skin allergens that can form while it's made. US safety reviewers set limits as low as 0.1 parts per million. They're unlikely in a well-made product, but it's a factor you can't see on the label.
Fair to say: the rating is based on harm to unborn young in animal tests at doses that also made the mothers sick. There were no fertility data. Canada found no concern.
Correct as of November 2026. What the badges mean
Sources
- Safe Work Australia. Hazardous Chemical Information System (HCIS): classifications for each chemical and for benzene and ethylene oxide. hcis.safeworkaustralia.gov.au
- US Cosmetic Ingredient Review. Final report on sodium lauryl sulfate and ammonium lauryl sulfate (1983); sodium alpha-olefin sulfonates (1998); sodium cetearyl sulfate and related alkyl sulfates, incl. sodium coco-sulfate (2010).
- Japan NITE. GHS classification results for sodium C14-16 olefin sulfonate. chem-info.nite.go.jp
The full source list is at the end of Chapter 1.