Methylchloroisothiazolinone

Methylchloroisothiazolinone is a chlorine-containing heterocyclic compound from the Isothiazolinone family. It is a white solid at room temperature, with good solubility in water, glycols, and other alcohols.

Methylchloroisothiazolinone is a globally approved broad-spectrum preservative for rinse-off, leave-on personal care, and household products. Thanks to its biocide action, it effectively prevents the growth of bacteria, mold, yeast, and microalgae in minimal concentrations up to 0.01%. It is used in aqueous applications such as hair and body care, cleansing products, perfume, liquid soaps, etc.

Active in a wide range of pH values, Methylchloroisothiazolinone is compatible with almost all surfactants (anionic, cationic, and nonionic), proteins, and other antimicrobial agents, including fungicides.

The combination of Methylchloroisothiazolinone and another preservative of the Isothiazolinone family, Methylisothiazolinone, is known under the trade name Kathon CG, where the MCI/MI ratio is 3:1. Kathon CG is used in many products to prevent the development of bacteria, mold, and fungi. It is used in minimal concentrations, in the range of 0.0003-0.0015%, and even in these concentrations, it reliably prevents the growth of microbes.

Unfortunately, Methylchloroisothiazolinone is a known allergen (like Methylisothiazolinone) with many confirmed contact dermatitis and sensitization cases. The first contact dermatitis to these substances appeared in the mid-seventies, and later, there was a noticeable increase in frequency and severity. In addition, it harms aqueous microorganisms and has a bad ecological profile. This preservative is not approved for use in pharmaceuticals.