Methylisothiazolinone (also called 2-methyl-4-isothiazolin-3-one), is a powerful synthetic biocide and preservative within the group of isothiazolinones.
Methylisothiazolinone is used to control slime-forming bacteria, fungi, and algae in pulp/paper mills, cooling water systems, oil field operations, industrial process waters, and air washer systems. And it is incorporated into adhesives, coatings, fuels, metal working fluids, resin emulsions, paints, and various other specialty industrial products as a preservative. It is also used to control the growth of mold, mildew, and sapstain on wood products. It is generally recommended for use only in rinse-off and leave-on cosmetic products (maximum concentration of 100 ppm) as preservative such as shampoo, conditioner, hair color, body wash, lotion, sunscreen, mascara, shaving cream, baby lotion, baby shampoo, hairspray, makeup remover, liquid soaps, and detergents. Nevertheless, methylisothiazolinone is allergenic. It is reported that methylisothiazolinone in rinse-off products causes allergic contact dermatitis.
