Methylchloroisothiazolinone contact skin allergen

Methylchloroisothiazolinone also called  (MCI or CMIT)

The molecule methylchloroisothiazolinone  (CAS 26172-55-4) causes contact dermatitis and was seen in many products world wide  in preparations like cosmetics, lotions, moisturizers, sanitary wipes, shampoos, dish washing detergents, body and hand products, baby wipes, shampoos and even mouth washes.  Methylchloroisothiazolinone is often pared with Methylisothiazolinone, it is a clear liquid with no fragrance tones.  It functions as a preservative and cytotoxin.

The allergies are being documented in journal articles and in the EU Scientific Committee on Consumer Safety (SCCS) in the document “THE SCIENTIFIC COMMITTEE ON COSMETIC PRODUCTS AND NON-FOOD PRODUCTS INTENDED FOR CONSUMERS”.  The first publication of the preservative as a contact allergen was in 1988. Cases of photoaggravated allergic contact dermatitis, i.e. worsening of skin lesions after sun exposure, have also been reported. 

Methylchloroisothiazolinone often causes contact dermatitis and persistent eczema and causes out breaks of with those who suffer psoriasis on the skin exposed to methylchloroisothiazolinone.  This is listed as a known human immune system toxicant or allergen in EU Banned and Restricted Fragrances and Canada.   However, we still see it in products in the United States, South American, Africa and Asia.  This is found as a food additive.  Clinical we see are seeing and increase with contact dermatitis from this allergen. It is active at 15 parts per million.

This is found in laundry detergents, soaps, and dish washing liquids – Be aware this causes eczema, skin rashes and skin inflammation!  Many cases the dermatologist will tell the patient to avoid the sun.  It can stay in the human body for months after exposure.

Allergen of the Day on this Website December 8th, 2022!

Skeletal formula of methylchloroisothiazolinone



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