Chemical / INCI Name:
Commonly a blend listed as Methylchloroisothiazolinone and Methylisothiazolinone.
Primary CAS Numbers:
26172-55-4 (for Methylchloroisothiazolinone) / 2682-20-4 (for Methylisothiazolinone)
Common Product Names:
CIT/MIT, CMIT/MIT, MCI/MI. A well-known trade name is Kathon CG
· Molecular Formula:
Varies for each component. For example, Methylchloroisothiazolinone is C?H?ClNOS
Uses:
It is a powerful, broad-spectrum biocide and preservative used to prevent microbial growth (bacteria, fungi, algae) in water-based products. Its key benefit is effectiveness at very low concentrations .
· Cosmetics & Personal Care: Primarily in rinse-off products like shampoos, shower gels, and liquid hand soaps .
· Industrial & Household Products: Paints, coatings, adhesives, metalworking fluids, laundry detergents, fabric softeners, and cleaning products .
· Water Treatment: Used in cooling towers, pulp/paper processing, and air washer systems
Origin
It is a synthetic organic compound. The commercial 50% solution is produced by dissolving glutaraldehyde in water, sometimes with stabilizers (e.g., up to 10% methanol) to prevent polymerization.
What does CIT/MIT do in a formulation?
- In-Can Preservative: Prevents spoilage during the shelf life of water-based products.
- Broad-Spectrum Biocide: Effective against a wide range of bacteria, fungi, and algae
Safety Profile:
· Potent Skin Sensitizer: This is the major safety concern. Both components, especially Methylchloroisothiazolinone (CIT), are known to cause allergic contact dermatitis .
· Use Concentration Limits: Strictly regulated due to sensitization risk.
· In the EU and US, the maximum allowed concentration in rinse-off cosmetics is typically 15 parts per million (ppm) of the active blend (at a 3:1 ratio of CIT:MIT) .
· Lower limits or restrictions apply for leave-on products.
· Handling Hazard: The concentrated product is toxic, corrosive, and a severe skin/eye irritant. It requires full personal protective equipment (PPE) .
Technical profile:
| Property | Values |
| Appearance | Pale yellow to yellow-green clear liquid |
| Active Content | 14% minimum (common commercial grade) |
| Typical Ratio (CIT:MIT) | Between 2.5:1 to 4:1 by weight |
| pH Range | 2.0 – 5.0 (for the concentrated product) |
| Density | 1.26 - 1.33 g/cm³ |
| Solubility | Miscible with water and lower alcohols |
| Recommended Use Level | Typically 0.02% - 0.3% of the final product formulation |