Methylisothiazolinone:Applications, limitation for concentration and Safety dosage

Methylisothiazolinone(MI) is a white solid. Isothiazolinones, a class of heterocycles, are used as biocides in numerous personal care products and other industrial applications.

Applications

Methylisothiazolinone can be used in cosmetic preservative. Main uses are leave-on products, namely hand and body lotions and moisturisers (including facial moisturisers), sun tanning lotions and some rinse-off products like shampoos (mostly zinc pyrithione based anti-dandruff shampoos), surfactants and conditioners.

limitation for concentration

A Methylisothiazolinone (synonym: 2-methyl 4-isothiazolin-3-one; CAS no.: 2682-20-4; Trade names: Neolone 950, Microcare MT, OriStar MIT, RH-24,573) constitutes 25% of MCI(methylchloroisothiazolinone)/MI, thus a maximum MI concentration of 3.5 ppm in all rinse-off products and 1.8 ppm in leave-on products sold in the United States. Because MI is believed to be a weaker sensitizer than MCI, in the early 2000s, MI alone was released as an individual preservative for industrial products.

In 2005, MI was approved for use as a pre servative in cosmetics and household products. Both the Cosmetic Ingredient Review in the United States and the European Scientific Committee on Consumer Safety evaluated MIVwhich alone is a less effective biocide than MCI/MIV and concluded that 100ppm was a safe concentration to use in cosmetics. The introduction of MI alone has therefore resulted in a more than 25-times in crease in the permitted concentration of MI in cosmetics from 3.75 ppminrinse-offand1.8 ppminleave-onproducts to100 ppm. Currently, no limitations exist for the concentration of MI in industrial products.

Safety dosage

Methylisothiazolinone was approved for use as a preservative in cosmetics in 2005 at a maximum concentration of 100 ppm (0.01%). Methylisothiazolinone Sensitization Based on animal local lymph node assays, Basketter et al catego rized Methylisothiazolinone as a moderate sensitizer. However, the United Nations Globally Harmonized System of Classification and Labeling of Chemicals have classified MI as a strong allergen. Rohm and Haas (now Dow Chemicals, Midland, Mich) has performed a series of both animal and human studies to assess the sensitization potential of MI. They concluded that MI sensitized only at high concentra tions (91000 ppm).^[1]

References

[1] MARI PAZ CASTANEDO-TARDANA Kathryn A Z. Methylisothiazolinone.[J]. Dermatitis, 2013, 24 1: 2-6. DOI:10.1097/DER.0b013e31827edc73.

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