An update of the risk assessment for methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) with focus on rinse-off products.
Methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) has been widely used during the last 20 years for the preservation of aqueous systems in cosmetics, toiletries and in various industrial applications. MCI/MI has a broad spectrum of activity against fungi and bacteria at very low concentrations. The allergic contact potential of MCI/MI has been known for many years. This paper provides a review of pre-clinical and clinical experimental studies as well as experience from dermatology clinics worldwide. This forms the basis for an update of the risk assessment for the use of MCI/MI in rinse-off products. The scientific data indicate that the actual sensitization rate observed with a contact allergen is extremely dependent on dose and type of exposure. This review of the data leads to the conclusion that, under normal use conditions, within the current permitted/ recommended use concentrations for MCI/MI of up to 15ppm, the risk of primary sensitization from the use of rinse-off products is negligible, and elicitation of allergic contact dermatitis in MCI/MI-sensitized individuals rare, after exposure to MCI/MI-preserved rinse-off products.
Department of Dermatology, University of Copenhagen, Gentofte Hospital, Denmark.
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D000818:Animals; D000900:Anti-Bacterial Agents / Q000009:adverse effects* / Q000032:analysis; D003358:Cosmetics / Q000009:adverse effects* / Q000032:analysis; D009783:Dermatitis, Occupational / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology*; D005260:Female; D006168:Guinea Pigs; D006801:Humans; D008297:Male; D016273:Occupational Exposure / Q000032:analysis; D010328:Patch Tests; D011310:Preservatives, Pharmaceutical / Q000009:adverse effects* / Q000032:analysis; D018570:Risk Assessment; D013844:Thiazoles / Q000009:adverse effects* / Q000032:analysis
D000900:Anti-Bacterial Agents; D003358:Cosmetics; D011310:Preservatives, Pharmaceutical; D013844:Thiazoles; C011506:2-methyl-4-isothiazolin-3-one; C011421:5-chloro-2-methyl-4-isothiazolin-3-one