Isothiazolinone

Isothiazolinone is a class of heterocyclic organic compounds used primarily as preservatives and biocides. The most widely encountered members are methylisothiazolinone (MIT) and methylchloroisothiazolinone (MCI), often used together as a preservative pair; chloromethylisothiazolinone (CMIT) is another common member, frequently used in mixtures such as CMIT/MIT or MCI/MIT. Other related isothiazolinones, including octylisothiazolinone (OIT) and benzisothiazolinone (BIT), are used in specific industrial or consumer products.

Isothiazolinones are valued for their broad-spectrum antimicrobial activity and stability in a range of formulations. They are used as preservatives in cosmetics and personal care products (shampoos, soaps, creams, and wet wipes), as well as in paints, coatings, adhesives, cleaners, metalworking fluids, and industrial water treatment.

Health and safety: Isothiazolinones can act as potent skin sensitizers. Repeated exposure can lead to allergic contact dermatitis in susceptible individuals, with potential for reactions from low concentrations. Occupational exposure, including in manufacturing and cleaning industries, is a particular concern. Cross-sensitization among related isothiazolinones has been reported.

Regulation and labeling: Due to allergenic potential, many regulatory authorities have restricted or banned certain isothiazolinones in some product categories and require explicit labeling on products that contain them. Some mixtures remain allowed in certain products or at limited concentrations, while others are phased out or restricted to specific uses. Risk assessment and consumer safety measures are common components of regulatory oversight.