Safety

Methylisothiazolinone (MIT) is a heterocyclic organic compound used as a preservative in cosmetics and personal care products in concentrations up to 0.01%. MIT is a colorless, clear liquid with a mild odor that is completely soluble in water; mostly soluble in acetonitrile, methanol, and hexane; and slightly soluble in xylene. Consistent with its solubility, dermal penetration is low. The Cosmetic Ingredient Review Expert Panel noted the in vitro evidence of neurotoxicity but concluded that the absence of any neurotoxicity findings in the many in vivo studies, including subchronic, chronic, and reproductive and developmental animal studies, suggests that MIT would not be neurotoxic as used in cosmetics. Although recognizing that MIT was a sensitizer in both animal and human studies, the panel concluded that there is a threshold dose response and that cosmetic products formulated to contain concentrations of MIT at 100 ppm (0.0 1%) or less would not be expected to pose a sensitization risk. Accordingly, MIT may be safely used as a preservative in cosmetics up to that concentration.

Definition

ChEBI: Methylisothiazolinone is a 1,2-thazole that is 4-isothiazolin-3-one bearing a methyl group on the nitrogen atom. It is a powerful biocide and preservative and is the minor active ingredient in the commercial product Kathon(TM). It has a role as an antifouling biocide, an antimicrobial agent and an antifungal agent.

Contact allergens

MI is generally associated with MCI, in Kathon? CG, MCI/MI, and Euxyl? K 100. This preservative is currently used in water-based products such as cosmetics, paints, and glues. Skin contact with concentrated solution can cause severe irritant dermatitis.