Methylisothiazolinone, MIT, or MI, is the

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The ...

with the formula S(CH)₂C(O)NCH₃. 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 used ...

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 are ...

Preparation

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: : NCSCH=CHC(O)NHCH3 -> SCH=CHC(O)NCH3 + HCN

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 1.5–15% 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 a type of antigen that produces an abnormally vigorous immune response in which the immune system fights off a perceived threat that would otherwise be harmless to the body. Such reactions are called allergies. In technical terms ...

and

cytotoxic Cytotoxicity is the quality of being toxic to cells. Examples of toxic agents are an immune cell or some types of venom, e.g. from the puff adder (''Bitis arietans'') or brown recluse spider (''Loxosceles reclusa''). Cell physiology Treating cells ...

, 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.European Scientific Committee on Cosmetic Products and Non-food Products Intended for Consumers (SCCNFP), adopted 2004
/ref> 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 dramatic rise in the rates of reported cases of contact allergy to MI, as detected by diagnostic patch tests, is unprecedented in Europe; there have been repeated warnings about the rise. The increase is primarily caused by increasing consumer exposure to MI from cosmetic products; exposures to MI in household products, paints and in the occupational setting also need to be considered. The delay in re-evaluation of the safety of MI in cosmetic products is of concern to the SCCS; it has adversely affected consumer safety."'' The

American Contact Dermatitis Society American(s) may refer to: * American, something of, from, or related to the United States of America, commonly known as the "United States" or "America" ** Americans, citizens and nationals of the United States of America ** American ancestry, pe ...

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 Benzisothiazolinone (BIT) is an organic compound with the formula C6H4SN(H)CO. A white solid, it is structurally related to isothiazole, and is part of a class of molecules called isothiazolinones. BIT is widely used as a preservative and antimic ...

and octylisothiazolinone have found that reactions may occur if present in sufficient amounts.

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 Assessment

2014 EPA Re-registration Review Docket with Public Commentary

Reregistration Eligibility Decision of MIT by US EPA
* {{HPD, 198
Material Safety Data Sheet for product containing 0.1-1% MIT

Commission Scientific Committee on Consumer Safety Opinion on Methylisothiazolinone (P94) Submission II (Sensitization only) SCCS/1521/13

Methylisothiazolinone at the National Library of Medicine

2014 EPA Re-registration Review Docket with Public Commentary

Photo album of self reported reactions to methylisothiazolinone
Preservatives Isothiazolidinones