The application of isothiazolinones is restricted by industry standards and product properties to ensure safety and efficacy:
Cosmetics industry: CMIT/MIT cannot be used in leave-on products (e.g., night creams, body lotions) in the EU (due to the risk of skin sensitization); it is only allowed in rinse-off products (e.g., shampoos, facial cleansers) with a concentration ≤0.0015%. BIT is allowed in leave-on products but must be labeled if the concentration exceeds 0.001%.
Food contact materials: Isothiazolinones (except for specific food-grade BIT) are not allowed to be used in materials that come into direct contact with food (e.g., plastic food containers, food packaging films) to avoid migration into food and endangering human health.
Water treatment industry: In drinking water treatment, isothiazolinones are not used (due to potential residues); they are only limited to industrial circulating water, swimming pools, and other non-drinking water systems, and the residual concentration in the water after use must meet the environmental discharge standards (e.g., ≤0.1 mg/L in China).
