CAS# 26172-55-4

Description:

METHYLCHLOROISOTHIAZOLINONE: Methylchloroisothiazolinone (also known as MCI) is a common ingredient often used in cosmetics and beauty products as a preservative. Methylchloroisothiazolinone is a potential allergen used in beauty products, although most reactions occurred in the 1980s and 1990s with leave in products, and it is now only used in much lower concentrations and in rinse off products, leading to much lower rates of allergic and irritant reactions, according to research.

In high concentrations Methylchloroisothiazolinone can cause chemical burns and it is a skin and membrane irritant. It was largely removed from most cosmetic products except for those with only short duration skin contact such as rinse-offs, although its inclusion in certain forms makes it more acceptable to sensitive users. It is used in concentrations of up to 15% in rinse-off products and 8% in other cosmetics (EWG). It is approved by the CIR for use in cosmetics.

In 2016, the Canadian goverrnment revised its Hot List to include additional warnings about this ingredient. Leave on products may no longer be formulated with this ingredient. As of June 2016, children’s products with this ingredient can no longer be sold in Canada.

Cosmetic Function(s):

• Preservative