Methylchloroisothiazolinone can cause allergic reactions in some people. 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. In Canada, methylchloroisothiazolinone may only be used in rinse-off products in combination with methylisothiazolinone, the total concentration of the combination may not exceed 15 ppm. Methylisothiazolinone is considered safe in the allowed amount in rinse-off products (0.01%) and safe in leave-in products when formulated to be non-sensitizing.
Incidents An overdose of Kathon by aircraft maintenance personnel, using 38 times the correct amount, resulted in damage to both engines of a
Titan Airways aircraft in February 2020. After losing both engines in succession, the
Airbus A321 made an emergency landing at
Gatwick Airport. The maintenance procedures specified the Kathon to be diluted to 100
PPM by volume, but with the aircraft maintenance technician being unfamiliar with the term "PPM" and the term not being defined in the aircraft maintenance manuals, the technician instead used an online calculator to convert PPM to percentages, misinterpreted the answer, and added 30 kg of Kathon to each wing tank, which was over 38 times the required amount. Over the course of the next day, the Kathon progressively caused more and more damage to the engines, finally resulting in an emergency landing. == References ==