Chapter 6: Preservatives
Methylchloroisothiazolinone / methylisothiazolinone (CMIT/MIT)
- Poison schedule (Australia)
- Officially classed skin allergen
The worst fact: it's such a strong allergen that the EU classes any product with just 0.0015% of it as a skin sensitiser. As a raw chemical it's rated "fatal in contact with skin". Australia's regulator says it's widely used here in cleaning, laundry and even baby products.
Why brands use it: it works at 15 parts per million or less, and it has been used since the 1980s.
Take care if: you're allergic to MIT. Many people who react to MIT also react to this mix.
Comes from: made in a lab. It's fully synthetic.
Myth check: "it's rinse-off, so it's harmless": rinsing doesn't remove the allergy risk, which is why the EU caps it.
Contaminants: nil.
Fair to say: at the legal limits in rinse-off products, most people never react.
Correct as of November 2026. What the badges mean
Sources
- Australian Government. Poisons Standard October 2026 (SUSMP), F2026L01327. Entries: methylisothiazolinone, methylchloroisothiazolinone, 2-phenoxyethanol, benzalkonium chloride. legislation.gov.au
- 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
- NICNAS (now AICIS). Isothiazolinones: Human health tier III assessment (2020); Methylchloroisothiazolinone IMAP assessment (2019); Bronopol IMAP assessment 1504 (2014). industrialchemicals.gov.au
- Reeder MJ, Atwater AR. Cutis 2019;104:94-96.
The full source list is at the end of Chapter 6.