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Methylisothiazolinone (MIT, MI)

  • Biocides
  • CAS 2682-20-4

Methylisothiazolinone (MIT, MI) (CAS 2682-20-4) appears in 15 of the 1,812 car-care products CarCareTruth tracks (as of June 2026), 1 of which carry a DANGER signal word on their published Safety Data Sheet. It is classified as a respiratory sensitizer (asthmagen).

Skin sensitizer (H317) and asthmagen. Significantly less potent sensitizer than CMIT, but still flagged by dermatologists as a common contact allergen. EU restricted in leave-on cosmetics (allowed in rinse-off at limited concentrations). Sensitized individuals can react at the trace concentrations present in detailing products.

Methylisothiazolinone (MIT) is the milder cousin of CMIT (methylchloroisothiazolinone). Both are widely used as preservatives in water-based products; MIT is sometimes used alone where CMIT cannot be (its sensitization rate is lower but still significant). Both appear on dermatology contact-allergy panels.

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 alone or in CMIT/MIT blends as a microbial growth inhibitor in water-based formulations at low concentrations (typically <100 ppm)

Common questions about Methylisothiazolinone (MIT, MI)

What is Methylisothiazolinone (MIT, MI) used for in car care?
Isothiazolinone preservative; used alone or in CMIT/MIT blends as a microbial growth inhibitor in water-based formulations at low concentrations (typically <100 ppm)
Is Methylisothiazolinone (MIT, MI) a VOC?
No. Methylisothiazolinone (MIT, MI) is not classified as a volatile organic compound (VOC).
Is Methylisothiazolinone (MIT, MI) on California's Proposition 65 list?
No. Methylisothiazolinone (MIT, MI) is not on California's Proposition 65 list.
Is Methylisothiazolinone (MIT, MI) a respiratory sensitizer?
Yes. Methylisothiazolinone (MIT, MI) is classified as a respiratory sensitizer (asthmagen).

15 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.