Methylisothiazolinone (), MIT, or MI, is the
organic compound
Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...
with the formula S(CH)
2C(O)NCH
3. It is a white solid.
Isothiazolinone
Isothiazolinone (; sometimes isothiazolone) is an organic compound with the formula (CH)2SN(H)CO. A white solid, it is structurally related to isothiazole. Isothiazolone itself is of limited interest, but several of its derivatives are widely us ...
s, a class of
heterocycles, are used as biocides in numerous personal care products and other industrial applications. MIT and related compounds have attracted much attention for their allergenic properties, e.g.
contact dermatitis
Contact dermatitis is a type of acute or chronic inflammation of the skin caused by exposure to chemical or physical agents. Symptoms of contact dermatitis can include itchy or dry skin, a red rash, bumps, blisters, or swelling. These rashes ...
.
Chemistry
It is prepared by
cyclization
A cyclic compound (or ring compound) is a term for a compound in the field of chemistry in which one or more series of atoms in the compound is connected to form a ring. Rings may vary in size from three to many atoms, and include examples where ...
of ''cis''-''N''-methyl-3-thiocyanoacrylamide:
:
The crystal and molecular structure of methylisothiazolinone, as determined by in situ cryocrystallography, was reported for the first time in 2024.
Applications
Methylisothiazolinone is used for controlling microbial growth in water-containing solutions. It is typically used in a formulation with
5-chloro-2-methyl-4-isothiazolin-3-one (CMIT), in a 3:1 mixture (CMIT:MIT) sold commercially as ''Kathon''. Kathon is supplied to manufacturers as a concentrated stock solution containing from 1.5 to 15% of CMIT/MIT.
Kathon also has been used to control slime in the manufacture of paper products that contact food. In addition, this product serves as an antimicrobial agent in latex adhesives and in paper coatings that also contact food.
Hazards
MIT is
allergenic
An allergen is an otherwise harmless substance that triggers an allergic reaction in sensitive individuals by stimulating an immune response.
In technical terms, an allergen is an antigen that is capable of stimulating a type-I hypersensitivity ...
and
cytotoxic
Cytotoxicity is the quality of being toxic to cells. Examples of toxic agents are toxic metals, toxic chemicals, microbe neurotoxins, radiation particles and even specific neurotransmitters when the system is out of balance. Also some types of dr ...
, and this has led to some concern over its use. A report released by the European Scientific Committee on Cosmetic Products and Non-food Products Intended for Consumers (SCCNFP) in 2003 also concluded that insufficient information was available to allow for an adequate risk assessment analysis of MIT.
Rising reports of consumer impact led to new research, including a report released in 2014 by the European Commission Scientific Committee on Consumer Safety which reported:
The
American Contact Dermatitis Society named methylisothiazolinone "contact allergen of the year" in 2013. The North American Contact Dermatitis Group found that methylisothiazolinone caused 10.9% positive reactions, being the third most common contact allergen in patch test results which surveyed close to 5000 contact dermatitis patients. Additionally, new research into cross reactivity of MIT-sensitized patients to variants
benzisothiazolinone and octylisothiazolinone have found that reactions may occur if present in sufficient amounts.
In the United States, the Environmental Protection Agency has a 1998 data sheet on methylisothiazolinone in their Pesticides section which reads in part "Human Health Assessment: Toxicity: In studies using laboratory animals, methylisothiazolinone has been shown to be of moderate acute toxicity by the oral and inhalation routes. It is highly acutely toxic when applied dermally or to the eye and is considered to be corrosive."
Regulation
In 2014, the European Commission Scientific Committee on Consumer Safety further issued a voluntary ban on the MCI/MI mixture from leave-on products such as body creams. The measure applied for products placed on the market after 16 July 2015." Shortly thereafter, Canada moved to adopt similar measures in its Cosmetic Ingredients Hotlist.
Based on the opinion of the Scientific Committee on Consumer Safety (SCCS) of 2013, Commission Regulation (EU) 2016/1198 of 22 July 2016 amending Annex V to Regulation (EC) No 1223/2009 of the European Parliament and of the council on cosmetic products banned the use of methylisothiazolinone in leave-on products (skin creams and lotions) effective 12 February 2017 and limited it to 0.01% in rinse-off products (e.g. shampoo). Effective 27 January 2018 (placing on the market), the maximum concentration in rinse-off products was reduced to 0.0015%.
References
External links
CMIT/MIT Assessment2014 EPA Re-registration Review Docket with Public CommentaryReregistration Eligibility Decision of MIT by US EPA* {{CPID, id=1924, name=Methylisothiazoline
Material Safety Data Sheet for product containing 0.1-1% MITCommission Scientific Committee on Consumer Safety Opinion on Methylisothiazolinone (P94) Submission II (Sensitization only) SCCS/1521/13Methylisothiazolinone at the National Library of Medicine2014 EPA Re-registration Review Docket with Public Commentary
Preservatives
Isothiazolinones
Methyl compounds