Contact allergy caused by isothiazolinone derivatives: an overview of non-cosmetic and unusual cosmetic sources

Contact allergy caused by isothiazolinone derivatives: an overview of non-cosmetic and unusual cosmetic sourcesThe isothiazolinone derivatives, methylchloroisothiazolinone (MCI), methylisothiazolinone (MI), benzisothiazolinone (BIT), and octylisothiazolinone (OIT), owing to their strong bactericide, fungicide and algicide properties, are widely used in non-cosmetic products, such as chemical (industrial) products, household detergents, and water-based paints, and the former two derivatives are also used in cosmetic products.However, given their inherent sensitization potential (with MCI > MI > BIT > OIT), allergic contact dermatitis is frequently observed, both in consumers as well as workers in various industries.In this review, we provide an update on the use of MCI/MI and MI in cosmetics, highlighting certain aspects of MI; the use of excessive concentrations, the presence in some less familiar cosmetic products, and the association with unusual clinical manifestations.Furthermore, the use of isothiazolinones in dishwashing and washing-machine liquids, cleaning agents for dental care, and their general presence in multi-purpose household detergents, which may elicit (airborne) allergic contact dermatitis, is discussed.Finally, we provide a brief overview of the use of isothiazolinone derivatives in the paint and textile industry, and of OIT in the leather industry in particular.