Methylchloroisothiazolinone (MCI) is effective against gram-positive and gram-negative bacteria, yeast and fungi so it functions as preservative. Methylchloroisothiazolinone is found in many water-based personal care products and cosmetics. It's used in rinse off products (e.g. in shampoos and conditioners). It's not used as single ingredient in our products rather than in mixture with Methylisothiazolinone (MI).