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Methylchloroisothiazolinone (CMIT)

  • Biocides
  • CAS 26172-55-4

Methylchloroisothiazolinone (CMIT) (CAS 26172-55-4) appears in 7 of the 1,812 car-care products CarCareTruth tracks (as of June 2026). It is classified as a respiratory sensitizer (asthmagen).

Documented skin sensitizer (H317) — one of the most common contact allergens in personal-care and cleaning products. Asthmagen (respiratory sensitization documented in occupational exposure). At the trace ppm concentrations typical in finished products, sensitized individuals can still react. Banned in EU leave-on cosmetics.

Methylchloroisothiazolinone (CMIT) is a potent biocide preservative used at trace concentrations in water-based products. CMIT/MIT blends are among the most common preservation systems in modern detailing chemistry — and also among the most documented skin and respiratory sensitizers in consumer products. Banned from EU leave-on cosmetics due to allergy prevalence.

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
Purpose: Isothiazolinone preservative; used at very low concentrations (typically <15 ppm) to inhibit microbial growth in water-based formulations. Almost always paired with methylisothiazolinone (MIT) as the 'Kathon' biocide blend

Common questions about Methylchloroisothiazolinone (CMIT)

What is Methylchloroisothiazolinone (CMIT) used for in car care?
Isothiazolinone preservative; used at very low concentrations (typically <15 ppm) to inhibit microbial growth in water-based formulations. Almost always paired with methylisothiazolinone (MIT) as the 'Kathon' biocide blend
Is Methylchloroisothiazolinone (CMIT) a VOC?
No. Methylchloroisothiazolinone (CMIT) is not classified as a volatile organic compound (VOC).
Is Methylchloroisothiazolinone (CMIT) on California's Proposition 65 list?
No. Methylchloroisothiazolinone (CMIT) is not on California's Proposition 65 list.
Is Methylchloroisothiazolinone (CMIT) a respiratory sensitizer?
Yes. Methylchloroisothiazolinone (CMIT) is classified as a respiratory sensitizer (asthmagen).

7 products contain this

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.