Chapter 6: Preservatives
Benzisothiazolinone (BIT)
- Officially classed skin allergen
The worst fact: it's the allergy that's rising now. At one Danish clinic, BIT allergy went from under 1 in 300 patients tested in 2014 to 1 in 20 in 2023, mostly from detergents and paints. The EU doesn't allow it as a preservative in cosmetics at all.
Why brands use it: it's a strong preservative at low levels.
Take care if: you have eczema or react to MIT.
Comes from: made in a lab. It's fully synthetic.
Myth check: "it's on the US EPA's safer list, so it's fine": it only gets a yellow triangle, the EPA's lower tier.
Contaminants: nil.
Fair to say: most people never react.
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, ethylene oxide, toluene, phenol and benzyl chloride. hcis.safeworkaustralia.gov.au
- Scientific Committee on Consumer Safety (SCCS). Opinions on methylisothiazolinone (SCCS/1557/15), benzisothiazolinone (SCCS/1482/12) and phenoxyethanol (SCCS/1575/16). health.ec.europa.eu
- US EPA. Safer Chemical Ingredients List. epa.gov/saferchoice
- Søgaard et al. Benzisothiazolinone contact allergy, 2014-2023. Contact Dermatitis 2025. doi:10.1111/cod.14818
The full source list is at the end of Chapter 6.