CMIT/MIT (methylchloroisothiazolinone / methylisothiazolinone)
- Preservatives
- CAS 55965-84-9
CMIT/MIT (methylchloroisothiazolinone / methylisothiazolinone) (CAS 55965-84-9) appears in 1 of the 2,122 car-care products CarCareTruth tracks (as of August 2026). It is classified as a respiratory sensitizer (asthmagen).
CMIT/MIT is a potent skin sensitizer and a documented respiratory sensitizer (asthmagen). It is one of the most common preservative contact allergens on dermatology patch-test panels, and CMIT in particular is restricted in leave-on cosmetics in the European Union. Sensitized individuals can react at the trace concentrations present in cleaning products. At mixture level in a diluted consumer product it usually falls below the concentration that would classify the finished mixture, but the ingredient-level sensitizer flags remain relevant to PPE guidance.
What it is
CMIT/MIT is a blend of methylchloroisothiazolinone (CMIT) and methylisothiazolinone (MIT), used as a broad-spectrum preservative in water-based products at very low (parts-per-million) concentrations. The reaction-mass CAS number 55965-84-9 refers to the CMIT/MIT combination as supplied.
Where it appears in car care
The blend appears in water-based detailing products that need microbial protection: glass cleaners, all-purpose cleaners, and other aqueous formulas. It is effective at trace levels, which is why finished-product concentrations are so low.
Why it is flagged
CMIT/MIT is a well-documented skin sensitizer and a respiratory sensitizer (asthmagen). It is a frequent cause of allergic contact dermatitis and appears on standard dermatology patch-test panels; CMIT is restricted in leave-on cosmetics in the European Union. Because the sensitizer flags come from the ingredient rather than the diluted mixture's GHS classification, they inform PPE guidance (skin and respiratory protection) even when the finished product's Section 2 does not carry a mixture-level sensitizer code. It is also acutely toxic to aquatic life on a mass basis, contributing to the environmental aquatic-toxicity profile despite trace use.
Health & environment profile
- VOC
- no
- Prop 65 listed
- no
- Asthmagen
- yes
- EPA Safer Choice
- no
- Aquatic toxicity
- yes
- Biodegradable
- no
- Bioaccumulative
- no
- Persistent
- no
- Ozone depleting
- no
- Microplastic
- no
- PFAS
- no
- Env. score
- 2/5
Common questions about CMIT/MIT (methylchloroisothiazolinone / methylisothiazolinone)
- What is CMIT/MIT (methylchloroisothiazolinone / methylisothiazolinone) used for in car care?
- Isothiazolinone preservative blend used at trace concentrations to prevent microbial growth in water-based formulations
- Is CMIT/MIT (methylchloroisothiazolinone / methylisothiazolinone) a VOC?
- No. CMIT/MIT (methylchloroisothiazolinone / methylisothiazolinone) is not classified as a volatile organic compound (VOC).
- Is CMIT/MIT (methylchloroisothiazolinone / methylisothiazolinone) on California's Proposition 65 list?
- No. CMIT/MIT (methylchloroisothiazolinone / methylisothiazolinone) is not on California's Proposition 65 list.
- Is CMIT/MIT (methylchloroisothiazolinone / methylisothiazolinone) a respiratory sensitizer?
- Yes. CMIT/MIT (methylchloroisothiazolinone / methylisothiazolinone) is classified as a respiratory sensitizer (asthmagen).
1 product contain this
Magic Finish Car Glass CleanerProp 65glass-cleaner
Related
Health and environment notes translate the manufacturer Safety Data Sheet, the GHS classification, and authoritative regulatory listings (California Prop 65, EPA). Not medical advice. They describe the ingredient itself; whether a hazard applies to a finished product depends on its concentration and how it's used.