Chapter 11: The supporting cast · Part 2: Thickeners
Hydroxyethylcellulose (HEC)
- Made from a hazardous chemical
The worst fact: it's made by reacting cellulose with ethylene oxide, which the WHO's cancer agency rates "carcinogenic to humans". We found no published measurements of leftover ethylene oxide in it.
Why brands use it: it's a non-ionic, water-soluble thickener, a key ingredient in many household cleaning products.
Take care if: no specific group. It has no Australian hazard classification.
Comes from: ethylene oxide reacted with cellulose and caustic soda. Australia classes ethylene oxide as "May cause genetic defects; May cause cancer". That doesn't mean it's in the product, but it's not a great starting point for something you clean with.
Myth check: "Cellulose derivatives are all the same": CMC is made with monochloroacetic acid, HEC with ethylene oxide.
Contaminants: nil.
Fair to say: it's gentle enough for artificial tears and eye drops, and a US cosmetic review found it safe as used.
Correct as of November 2026. What the badges mean
Sources
- Safe Work Australia. Hazardous Chemical Information System (HCIS): classifications for calcium chloride, boric acid, borax, and for N-vinylpyrrolidone, vinyl acetate, ethylene oxide, 1,4-dioxane, hydrazine, aniline, p-toluidine, styrene, chloromethane, carbon monoxide and octamethylcyclotetrasiloxane (D4).
- HSDB (US National Library of Medicine), via PubChem: manufacturing, use and impurity data.
The full source list is at the end of Chapter 11.