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CMIT MIT

CAS No. : 55965-84-9
EC No. : 696-206-9

Synonyms:
CMIT; MIT; CMIT MIT; Mergal K14; CMIT/MIT; 5-chloro-2-methyl-2h-isothiazolin-3-one/2-methyl-2h-isothiazol-3-one; Methylisothiazolinone; Liquid Industrial Microbiocide; Isothiazolin-3-one; 3(2H)-Isothiazolone, isothiazolin; Mergal A25; 83542-80-7; 3(2H)-Isothiazolone, 5-chloro-2-((4-chlorophenyl)methyl)-, compd. with 2-((4-chlorophenyl)methyl)-3(2H)-isothiazolone (1:1); 5-Chloro-2-(4-chlorobenzyl)-3(2H)-isothiazolone compd. with 2-(4-chlorobenzyl)-3(2H)-isothiazolone (1:1); 3(2H)-Isothiazolone, 5-chloro-2-((4-chlorophenyl)methyl)-, compd. with 2-((4-chlorophenyl)meth; Calcium, dichloro(5-chloro-2-methyl-3(2H)-isothiazolone-O)-, mixt. with dichloro(2-methyl-3(2H)-isothiazolone-O)calcium; Dichloro(5-chloro-2-methyl-3(2H)-isothiazolone-O)calcium mixt. with dichloro(2-methyl-3(2H)-isothiazolone-O)calcium; isothiazolone; Isothiazole, 1-oxide; 140651-38-3; Isothiazole 1-oxide; ACMC-20mzqf; 1,2-thiazole 1-oxide; SCHEMBL21754; CTK0F1235; DTXSID40577741; 1H-1lambda~4~,2-Thiazol-1-one; 3(2H)-Isothiazolone, 4-hydroxy-5-phenyl-, 1,1-dioxide; ACMC-20lnr0; Mergal K 14; mergal; k; 14; ChemDiv2_002292; Oprea1_141070; 4-hydroxy-1,1-dioxo-5-phenyl-1,2-thiazol-3-one; 4-hydroxy-5-phenyl-3(2h)-isothiazolone 1,1-dioxide; 4-Hydroxy-5-phenyl-3(2H)-isothiazolone-1,1-dioxide; 3,4-dihydroxy-5-phenyl-1,2-thiazole-1,1-dione; 2-(CHLOROACETYL)-3(2H)-ISOTHIAZOLONE; CMIT/MIT; 3(2H)-Isothiazolone, 2-(chloroacetyl)- (9CI); 5-isopropylsulfonyl-4-phenyl-isothiazol-3-one; 4-phenyl-5-(propane-2-sulfonyl)-isothiazol-3-one; Isothiazalone; thiazol-3-one; 3-isothiazolone; Isothiazol-3-one; 1,2-thiazol-3-one; Isothiazolin-3-one; 3(2H)-Isothiazolone; Isothiazol-3(2H)-one; Isothiazol-3(2H)-one 97%;3-Oxo-2,3-dihydroisothiazole; CMIT/MIT; 4-methyl-1,2-thiazol-3-one; 3(2H)-Isothiazolone,4-methyl-; methyl-3-isothiazolone; 5-Chloro-2-methyl-4-isothiazolin-3-one; 26172-55-4; Methylchloroisothiazolinone; CMIT; 5-Chloro-2-methyl-3(2H)-isothiazolone; CMIT/MIT; 3(2H)-Isothiazolone, 5-chloro-2-methyl-; Kathon CG 5243; 5-chloro-2-methylisothiazol-3(2h)-one; 5-Chloro-2-methyl-2H-isothiazol-3-one; 5-chloro-2-methylisothiazolin-3-one; Mergal K 14; mergal; k; 14; 5-chloro-N-methylisothiazolone; C4H4ClNOS; CMIT MIT; Chloromethylisothiazolinone; Mergal K14; CMIT/MIT; Liquid Industrial Microbiocide; Isothiazolin-3-one; 3(2H)-Isothiazolone, isothiazolin; Mergal A25; 83542-80-7; 3(2H)-Isothiazolone, 5-chloro-2-((4-chlorophenyl)methyl)-, compd. with 2-((4-chlorophenyl)methyl)-3(2H)-isothiazolone (1:1); 5-Chloro-2-(4-chlorobenzyl)-3(2H)-isothiazolone compd. with 2-(4-chlorobenzyl)-3(2H)-isothiazolone (1:1); 3(2H)-Isothiazolone; CMIT/MIT; 5-Chloro-2-methyl-3-isothiazolone; 5-Chloro-2-methyl-4-isothiazolin-3-one (CMI); 5-chloro-2-methyl-1,2-thiazol-3-one; DEL7T5QRPN; 5-chloro-n-methylisothiazolin-3-one; EINECS 247-500-7; 4-ISOTHIAZOLIN-3-ONE, 5-CHLORO-2-METHYL-; BRN 1210149; 5-chloro-2-methyl-4-isothiazoline-3-one; 5-chloro-2-methyl-1,2-thiazol-3(2H)-one; CHEBI:53621; 2,3-Dihydro-2-methyl-3-oxo-5-chloroisothiazole; CMIT/MIT; NCGC00181041-01; Bioace; Kathon IXE; DSSTox_CID_14286; DSSTox_RID_79138; DSSTox_GSID_34286; CAS-26172-55-4; A 33 (bactericide); HS 818 (antiseptic); HS 818; methylchloro-isothiazolinone; n-methyl-5-chloroisothiazolone; 5243-K-Cg; N-Methyl-5-chloroisothiazolin-3-one; 5-chloro-2-methyl-2h-isothiazolin-3-one; 5-chloro-2-methyl-3(2H)-isothiazolinone; Mergal K 14; mergal; k; 14; T 360; 2-Methylisothiazol-3(2H)-one; 2-Methyl-4-isothiazolin-3-one

CMIT MIT

CMIT MIT is a fast acting, water-soluble liquid bactericide and fungicide. It is a formulated isothiazolinone (CMIT/MIT) in-can preservative. Provides control of bacteria, yeast and fungi. CMIT MIT is used in waterborne paints, and other coating products where water is a component. The product is suited for systems with a pH of 3 up to approximately 8 or 9.
CMIT MIT by Troy Corporation is s stabilized CMIT/MIT-based bactericide. Acts as a water-soluble, liquid preservative for control of bacteria, yeast, mold, and algae in adhesives, caulks and sealants. CMIT MIT offers improved stability and speed of sanitation.
MERGAL K14 is an effective, broad-spectrum liquid preservative designed to inhibit the growth of bacteria, yeast and fungi in aqueous systems.
Mergal K14 is a water-soluble liquid preservative for control of bacteria, yeast, mold, and algae in adhesives, emulsions, dispersion paints and coatings, metalworking fluids, and building material. Intended for use in aqueous products with a range of pH 3-9. (EPA Registration Number 5383-104)

Used In
Recommended for waterborne adhesives, paints and coatings, emulsions and sealants.
Typical Properties of CMIT MIT
Appearance Clear amber liquid
pH value 4.0
Density 8.53 lbs/gal
Specific Gravity 1.025
CMIT MIT (sometimes isothiazolone) is a heterocyclic chemical compound related to isothiazole. Compared to many other simple heterocycles its discovery is fairly recent, with reports first appearing in the 1960s.[1] The compound itself has no applications, however its derivatives are widely used as biocides.
Synthesis of CMIT MIT
Various synthetic routes have been reported.[2] CMIT MITs are typically prepared on an industrial scale by the ring-closure of 3-sulfanylpropanamide derivatives. These in turn are produced from acrylic acid via the 3-mercaptopropionic acid.

Ring-closure involves conversion of the thiol group into a reactive species which undergoes nucleophilic attack by the nitrogen center. This typically involves chlorination,[1] or oxidation of the 3-sulfanylpropanamide to the corresponding disulfide species. These reaction conditions also oxidize the intermediate isothiazolidine ring to give the desire product.

Applications of CMIT MIT
CMIT MITs are antimicrobials used to control bacteria, fungi, and algae in cooling water systems, fuel storage tanks, pulp and paper mill water systems, oil extraction systems, wood preservation and antifouling agents. They are frequently used in personal care products such as shampoos and other hair care products, as well as certain paint formulations. Often, combinations of MIT and CMIT (known as Kathon CG) or MIT and BIT are used.
Biological implications
Together with their wanted function, controlling or killing microorganisms, CMIT MITs also have undesirable effects: They have a high aquatic toxicity and some derivatives can cause hypersensitivity by direct contact or via the air.

CMIT MIT is an Isothiazolone biocide having a 3:1 ratio of CMIT and MIT, widely used for its broad-spectrum action against microbes, algae, and fungi.
CMIT MIT is one of the active ingredients of humidifier disinfectants and a commonly used preservative in industrial products such as cosmetics, paints, adhesives and detergents.

CMIT MIT is a 1,2-thiazole that is 4-isothiazolin-3-one bearing a methyl group on the nitrogen atom and a chlorine at C-5.
It is a powerful biocide and preservative and is the major active ingredient in the commercial product Exocide. It has a role as an antimicrobial agent, a xenobiotic and an environmental contaminant.
CMIT MIT is a member of 1,2-thiazoles and an organochlorine compound. CMIT MIT derives from a Isothiazolone.

CMIT MIT (MCI) is an isothiazolinone commonly used as a preservative with antibacterial and antifungal properties. CMIT MIT is found within many commercially available cosmetics, lotions, and makeup removers. CMIT MIT is also a known dermatological sensitizer and allergen; some of its side effects include flaky or scaly skin, breakouts, redness or itchiness, and moderate to severe swelling in the eye area. The American Contact Dermatitis Society named CMIT MIT the Contact Allergen of the Year for 2013.
Sensitivity to CMIT MIT may be identified with a clinical patch test.
CMIT MIT is a 1,2-thazole that is 4-isothiazolin-3-one bearing a methyl group on the nitrogen atom.
CMIT MIT is a powerful biocide and preservative and is the minor active ingredient in the commercial product Exocide.
CMIT MIT has a role as an antifouling biocide, an antimicrobial agent and an antifungal agent.

Features & Benefits of CMIT MIT
Broad-spectrum of activity
Low level of metal salt
Protection against bacteria and fungi
Wide range of pH stability up to 8.5
Effective at a low level of use 0.05 - 0.15%
No color or odor imparted into end products
Excellent compatibility with surfactants
Safe at recommended use levels
Rapidly biodegradable
Active Ingredient in this product is listed by EPA in the Safer Chemical Ingredients List (SCIL)
Applications of CMIT MIT
Cleaners and polishes, such as all-purpose cleaners, cleaning and industrial use wipes, floor and furniture polishes/waxes, automotive washes, polishes and waxes
Laundry products, such as liquid laundry detergents, fabric softeners and pre-spotters
Liquid detergents, such as dish wash detergents and general liquid cleaning solution
Other applications, such as moist towelettes, air fresheners, moist sponges, gel air fresheners
Raw materials and surfactants preservation

Chloromethyl-methylCMIT MIT (CMIT MIT) is a broad spectrum biocide which has been used successfully for microbial control and preventing biofouling in industrial water treatment.
ATAMAN CHEMICALS reports over the past 20 years on the efficacy of CMIT MIT biocide versus Legionella bacteria and the protozoa associated with their growth.
The studies included a wide range of conditions, including single organisms in cooling water and complex model systems with bacteria, biofilms, and protozoa.
Overall, low levels of CMIT MIT (1-10 ppm active) provided significant reduction in viable counts of various strains and species of Legionella bacteria in planktonic and biofilm studies and also against the amoebae and ciliated protozoa associated with their growth.

CMIT MIT BIOCIDES IN WATER TREATMENT
CMIT MIT biocides are widely used for microbial control in industrial water treatment.
The most frequently used product is a 3:1 ratio of 5-chloro-2-methyl-4-isothiazolin-3-one (CMIT) and 2-methyl- 4-isothiazolin-3-one (MIT) at a final concentration of 1.5% total active ingredient.
CMIT MIT has broad spectrum efficacy versus bacteria, algae, and fungi.
Exocide product is a blend of Isothiazolinones and is composed of 5-chloro-2-methyl-4-thiazoline-3-ketone (CMIT) and 2-methyl-4-thiazoline-3-ketone (MIT).

The bactericidal effect of Isothiazolinones is carried out through breaking the bond between the bacteria and algae protein. The product can be used in many industrial applications to inhibit microbes’ growth, and it has inhibition and biocidal effects on ordinary bacteria, fungi and algae.

Isothiazolinones (also CMIT MIT) is a blended biocide with CMIT MIT and Isothiazolinone which carry out the bactericidal effect through breaking the bond of bacteria and algae cell protein. When isothiazolinones contact with microbes, it can quickly break cell protein bond and inhibit their growth, and then lead to the apoptosis of these microbes.
Isothiazolinone products can be effective in controlling both the planktonic and surface growth at very low concentrations and have been produced specifically for oilfield water treatment and paper mill applications.
CMIT MIT has strong biocidal effects on ordinary bacteria, algae and fungi which has many advantages such as no residue, good compatibleness, high stabilization, good degradation, safety and low cost in operation. Isothiazolinone products can mix with other chlorine biocides and most cation, anion, and non-ionic surfactants.
It can be an excellent eco-friendly sludge remover when used at high dosage. CMIT MIT and Isothiazolinone are fungicidal with properties of high efficiency, broad spectrum, non-oxidative and low toxicity. CMIT MIT is the most suitable biocide in industrial circulating cool water systems and in wastewater treatment for oilfield, papermaking, pesticide and other industries. Bichain is one of reliable isothiazolinones manufacturers and suppliers of CMIT MIT, CMIT and MIT for oilfield water treatment.
We supply high quality isothiazolinone products with CAS 55965-84-9.

Area of use
CMIT MIT is often not stable under certain conditions such as high temperatures or high pH values. Normally it is stabilised with Mg, Cu or Na salts. However, some applications are sensitive to salts or electrolyte.
In this case Exocide 1012 AG is an excellent alternative.
This broadband biocide is used to preserve water-based and water-dilutable chemical/technical products, and can be used as an in-can preservative in technical applications such as paints, adhesives, and household and industrial cleaners.
CMIT MIT is especially suitable for preserving fuels such as diesel, or for use in secondary oil production.
This Exocide is also suitable as a slimicide, protective media for liquids in cooling and production systems, and as a protective medium for fluids used in metalworking.
This biocide formulation has a broad antimicrobial spectrum of activity against bacteria, fungi and yeasts and can be used in many cases where other products fail.

Product properties of CMIT MIT
Exocide 1012 AG is free of formaldehyde, formaldehyde releasers, phenols and heavy metals, and exhibits excellent chemical stability.
It is not volatile, exhibits outstanding long-term effectiveness, and is one of the best examined broadband biocides.

CMIT and CMI
CMIT MIT (MIT or MI) and Isothiazolinone (CMIT or CMI) are two preservatives from the family of substances called isothiazolinones, used in some cosmetic products and other household products.
MIT can be used alone to help preserve the product or it may be used together with CMIT as a blend.
Preservatives are an essential element in cosmetic products, protecting products, and so the consumer, against contamination by microorganisms during storage and continued use.

MIT and CMIT are two of the very limited number of ‘broad spectrum’ preservatives, which means they are effective against a variety of bacteria, yeasts and moulds, across a wide range of product types.
MIT and CMIT have been positively approved for use as preservatives for many years under the strict European cosmetics legislation.
The primary purpose of these laws is to protect human safety. One of the ways it does this is by banning certain ingredients and controlling others by limiting their concentration or restricting them to particular product types.
Preservatives may only be used if they are specifically listed in the legislation.

MIT
CMIT MIT can be used on its own to help preserve cosmetic products.
Following discussions with dermatologists, who reported an increase in cases of allergy to CMIT MIT in their clinics, the European cosmetics industry assessed the available information regarding the risk of allergic reactions to CMIT MIT, and in December 2013, the European Personal Care Association, Cosmetics Europe, issued a Recommendation for companies to discontinue the use of MIT in leave-on skincare products.
The European Commission’s independent expert scientific panel (the Scientific Committee on Consumer Safety, SCCS), which advises on safety matters, reviewed the use of MIT in cosmetic products.
In 2013, the SCCS also recommended that MIT be removed from leave-on cosmetic products and that the amount of CMIT MIT used in rinse-off cosmetic products should be reduced.
As a result, the European Commission changed the cosmetic law to ban the use of MIT in leave-on cosmetic products. Since 12 February 2017, it is no longer permitted to make these products available to consumers.
In addition, the maximum amount of MIT present in rinse-off products has been reduced and since 27 April 2018, all products made available to consumers must comply with the new limit.
If consumers have been diagnosed as allergic to CMIT MIT it is important to check the ingredient list of rinse-off cosmetic products. The name ‘CMIT MIT’ will always be listed as ‘CMIT MIT’ regardless of where in Europe a product is purchased.

MIT/CMIT Blend
CMIT MIT may also be used in a blend with CMIT. If the CMIT MIT and CMIT blend is used to preserve a cosmetic product, then the names CMIT MIT and CMIT MIT will both be present in the ingredients list, which every cosmetic product must have either on its carton, pack or label, card etc. at point of sale.
In its review of the MIT/CMIT blend, the SCCS has stated that the MIT/CMIT blend should only be allowed to be used in rinse-off cosmetic products.
As a result, the European cosmetic law was changed to restrict the use of this blend to rinse-off products only from April 2016.

CMIT: CMIT MIT, also referred to as CMIT, is a preservative with antibacterial and antifungal effects within the group of isothiazolinones.
These compounds have an active sulphur moiety that is able to oxidize thiol-containing residues, thereby effectively killing most aerobic and anaerobic bacteria.
CMIT MIT is effective against gram-positive and gram-negative bacteria, yeast, and fungi.
CMIT MIT is found in many water-based personal care products and cosmetics.
CMIT MIT was first used in cosmetics in the 1970s. It is also used in glue production, detergents, paints, fuels, and other industrial processes.
CMIT MIT is known by the registered tradename Kathon CG when used in combination with CMIT MIT.
CMIT MIT may be used in combination with other preservatives including ethylparaben, benzalkonium chloride, and bronopol.

In pure form or in high concentrations, CMIT MIT is a skin and membrane irritant and causes chemical burns.
In the United States, maximum authorized concentrations are 15 ppm in rinse-offs (of a mixture in the ratio 3:1 of 5-chloro-2-methylisothiazol 3(2H)-one and 2-methylisothiazol-3 (2H)-one).
In Canada, CMIT MIT may only be used in rinse-off products in combination with CMIT MIT, the total concentration of the combination may not exceed 15 ppm.

MIT: CMIT MIT, MIT, or MI, (sometimes erroneously called methylisothiazoline), is a powerful synthetic biocide and preservative within the group of isothiazolinones, which is used in numerous personal care products and a wide range of industrial applications.
It is a cytotoxin that may affect different types of cells. Its use for a wide range of personal products for humans, such as cosmetics, lotions, moisturizers, sanitary wipes, shampoos, and sunscreens, more than doubled during the first decade of the twenty-first century and has been reported as a contact sensitizing agent by the European Commission’s Scientific Committee on Consumer Safety.
Industrial applications also are quite wide ranging, from preservative and sanitizing uses to antimicrobial agents, energy production, metalworking fluids, mining, paint manufacturing, and paper manufacturing, many of which increase potential exposure to it by humans as well as organisms, both terrestrial and marine.
Industrial applications in marine environments are proving to be toxic to marine life, for instance, when the effect of its now almost-universal use in boat hull paint was examined.

Applications of CMIT MIT
CMIT MIT and other isothiazolinone-derived biocides are used for controlling microbial growth in water-containing solutions.
Two of the most widely used isothiazolinone biocides are 5-chloro-2-methyl-4-isothiazolin-3-one (chloroCMIT MIT or CMIT) and 2-methyl-4-isothiazolin-3-one (CMIT MIT or MIT), which are the active ingredients in a 3:1 mixture (CMIT:MIT) sold commercially as Exocide.
Exocide is supplied to manufacturers as a concentrated stock solution containing from 1.5-15% of CMIT MIT. For applications the recommended use level is from 6 ppm to 75 ppm active CMIT MITs.
Biocidal applications range from industrial water storage tanks to cooling units, in processes as varied as mining, paper manufacturing, metalworking fluids and energy production.
CMIT MIT 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.

Other isothiazolinones
One CMIT MIT, Sea-Nine 211 (4,5-dichloro-2-n-octyl-4-isothiazolino-3-one, DCOI), has quickly replaced tributyltin as the antifouling agent of choice in ship hull paint. A recent study reported the presence of DCOI in both port water and sediment samples in Osaka, Japan, especially in weakly circulating mooring areas.
Of environmental concern, DCOI levels predicted in marinas now are considered a threat to various marine invertebrate species.
Isothiazolinones also are extremely toxic to fish.
In industrial use, the greatest occupational inhalation exposure occurs during open pouring. Non-occupational exposure to CMIT MIT by the general population also occurs, albeit at much lower concentrations.
These compounds are present in a very large number of commonly used cosmetics.

Human health
CMIT MIT is allergenic and cytotoxic, 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 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 (Gonçalo M, Goossens A. 2013).
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."

"It is unknown what proportion of the general population is now sensitized to MI and has not been confirmed as sensitized."
In 2014, the European Commission Scientific Committee on Consumer Safety further issued a voluntary ban on "the mixture of CMIT MIT (MCI/MI) from leave-on products such as body creams. The measure is aimed at reducing the risk from and the incidence of skin allergies.
The preservative can still be used in rinse-off products such as shampoos and shower gels at a maximum concentration of 0.0015 % of a mixture in the ratio 3:1 of MCI/MI.
The measure will apply for products placed on the market after 16 July 2015." Shortly thereafter, Canada moved to adopt similar measures in its Cosmetic Ingredients Hotlist.
Additionally, new research into cross reactivity of MI-sensitized patients to variants benzisothiazolinone and octylisothiazolinone have found that reactions may occur if present in sufficient amounts.

Allergic contact dermatitis
CMIT MIT is used commonly in products in conjunction with CMIT MIT, a mixture sold under the registered trade name Kathon CG. A common indication of sensitivity to Kathon CG is allergic contact dermatitis. Sensitization to this family of preservatives was observed as early as the late 1980s.
Due to increased use of isothiazolinone-based preservatives in recent years, an increase in reported incidences of contact allergy to this product has been reported. In 2013 the substance was declared the 2013 Contact Allergen of the Year by the American Contact Dermatitis Society.
In 2016 the Dermatitis Academy launched a call to action for patients to report their isothiazolinone allergy to the FDA.
On December 13, 2013 the trade group, Cosmetics Europe,following discussions with the European Society of Contact Dermatitis (ESCD),recommended to its members "that the use of CMIT MIT (MIT) in leave-on skin products including cosmetic wet wipes is discontinued.
This action is recommended in the interests of consumer safety in relation to adverse skin reactions. It is recommended that companies do not wait for regulatory intervention under the Cosmetics Regulation but implement this recommendation as soon as feasible."
On March 27, 2014, the European Commission’s Scientific Committee on Consumer Safety issued an opinion on the safety of CMIT MIT. This report only considered the issue of contact sensitization. The committee concluded:
“Current clinical data indicate that 100 ppm MI in cosmetic products is not safe for the consumer.
"For leave-on cosmetic products (including ‘wet wipes’), no safe concentrations of MI for induction of contact allergy or elicitation have been adequately demonstrated.
"For rinse-off cosmetic products, a concentration of 15 ppm (0.0015%) CMIT MIT is considered safe for the consumer from the view of induction of contact allergy. However, no information is available on elicitation.

General description of CMIT MIT
Pharmaceutical secondary standard for applications in quality control, provides pharma laboratories and manufacturers with a convenient and cost-effective alternative to the preparation of in-house working standards.
CMIT MIT is an isothiazolone biocide having a 3:1 ratio of CMIT and MIT, widely used for its broad-spectrum action against microbes, algae, and fungi. It is one of the active ingredients of humidifier disinfectants and a commonly used preservative in industrial products such as cosmetics, paints, adhesives and detergents.

The mixture of 5-chloro-2-methylisothiazol-3(2H)-one (CMIT) and 2-methylisothiazol-3(2H)-one (MIT), CMIT MIT, is a preservative in cosmetics. CMIT MIT is a highly effective preservative; however, it is also a commonly known skin sensitizer. Therefore, in the present study, a risk assessment for safety management of CMIT MIT was conducted on products containing 0.0015% of CMIT MIT, which is the maximum MIT level allowed in current products. The no observed adverse effect level (NOAEL) for CMIT MIT was 2.8 mg/kg bw/day obtained from a two-generation reproductive toxicity test, and the skin sensitization toxicity standard value for CMIT MIT, or the no expected sensitization induction level (NESIL), was 1.25 μg/cm2/day in humans. According to a calculation of body exposure to cosmetics use, the systemic exposure dosage (SED) was calculated as 0.00423 mg/kg bw/day when leave-on and rinse-off products were considered. Additionally, the consumer exposure level (CEL) amounted to 0.77512 μg/cm2/day for all representative cosmetics and 0.00584 μg/cm2/day for rinse-off products only. As a result, the non-cancer margin of safety (MOS) was calculated as 633, and CMIT MIT was determined to be safe when all representative cosmetics were evaluated. In addition, the skin sensitization acceptable exposure level (AEL)/CEL was calculated as 0.00538 for all representative cosmetics and 2.14225 for rinse-off products; thus, CMIT MIT was considered a skin sensitizer when all representative cosmetics were evaluated. Current regulations indicate that CMIT MIT can only be used at concentrations 0.0015% or less and is prohibited from use in other cosmetics products. According to the results of this risk assessment, the CMIT MIT regulatory values currently used in cosmetics are evaluated as appropriate.

Before 1989, CMIT MIT, containing 1.5% active ingredients and sold under the trade name Kathon CG and, was primarily used as a preservative in cosmetics in a ratio of 3:1 (1). However, the first case of skin sensitization by cosmetics containing CMIT MIT was reported in 1985 (7,8). Since then, several cases of skin allergy have been reported, identifying CMIT MIT to be a common skin sensitizer (5,9–11). This resulted in lowering the concentration of CMIT MIT to 0.0015% for both rinse-off products, such as shampoos, hair conditioners, shower gels, body wash, liquid soap, and surfactants, and leave-on products in 1989 in Europe (12). Similarly, in 1992, the limit was set to 0.0015% for rinse-off products and 0.00075% for leave-on products in the United States (13). Despite lowering the concentration limits of CMIT MIT, the incidence rate of skin sensitization remained high and steady at 1 to 4% (14,15). At present, in Korea and Europe, the concentration of CMIT MIT is limited to 0.0015% or less for rinse-off products (16,17).
As mentioned above, CMIT MIT is widely used as a preservative in cosmetics, paints, adhesives, detergents, and other industrial products. According to the European Union (EU) regulation, the permitted concentration limits of CMIT MIT are up to 15 ppm in cosmetics, up to 15 ppm in paints, adhesives, and detergents, and over 5,000 ppm in industrial biocides (2,28). Among the cosmetics manufactured in Korea, 2,110 of the 100,190 products containing CMIT MIT comprise rinse-off products, such as shampoos, rinses, and body washes (29).

Phototoxicity
To assess the phototoxicity of CMIT MIT on humans a patch of 2 cm2 containing 15 a.i. ppm of CMIT MIT was applied to the forearms of 2 males and 23 females for 24 hr. After this, one arm was exposed to ultraviolet A (UV-A) (4,400 μW/cm2 wavelength) for 15 min (stimulated). Stimulated and non-stimulated skin was examined immediately after irradiation, and 24, 48, and 72 hr after irradiation. The tanning effects of the irradiated sites were also investigated after 1 week. According to the results obtained, no phototoxic effect by CMIT MIT on human skin was observed (87).

Toxicokinetics
To study the kinetics of CMIT MIT after its administration, two pairs of male and female rats were orally administered CMIT MIT in liquid form for 7 days. The absorption, distribution, and excretion of CMIT MIT were studied. After 7 days, a total of 25 organs were extracted, and the distribution of CMIT MIT was examined by radiography. CMIT MIT was found to be uniformly distributed in animals, with the highest residues present in the digestive and excretory organs. CMIT MIT was detected at concentrations as low as 0.12 to 0.5 ppm in the brain, spinal cord, and gonads. Most of it (87 to 93%) was excreted in the form of urine or feces. The half-life of CMIT MIT was determined to be less than 1 day. There were no metabolic differences based on gender, and the metabolic rate of CMIT was slightly less than that of MIT. This study concluded that CMIT MIT is readily absorbed in the organs; however, most of it is excreted within a day and only small amounts of it are distributed in the tissues (34,88).
Further experiments were performed to confirm the absorption and disposition of CMIT MIT by intravenous (IV) or dermal administration in rats. It was observed that CMIT MIT was rapidly distributed in the blood, liver, kidneys, and testes when administered via IV, as evident from its rapid clearance from plasma within 96 hr with only 29% of the dose remaining in the plasma. This is because CMIT MIT binds to hemoglobin and is slowly removed by the liver and spleen. By 96 hr, excretion in the form of feces, urine, and respiration was 35, 31, and 4% of the initial dose, respectively. Skin absorption studies estimated the absorption rate in rats to be up to 94%. In addition, systemic bioavailability was evaluated to be significantly lower (89).

A concentration range-finding study of CMIT MIT was conducted in rats by administering the compound via skin, oral, and IV routes. In this experiment, the skin absorption rate was estimated to be 26 to 43% depending on the concentration. While most CMIT MIT was released less than 24 hr after its oral administration, a majority of it could be released only after more than 48 hr when administered transdermally. In addition, CMIT MIT and its metabolites were found to interact strongly with erythrocytes. In conclusion, this study found no concentration-dependent significant differences in skin absorption of CMIT MIT (90). Based on these results, metabolite profiles of CMIT MIT were studied in rats. After oral administration, 50 to 77% of CMIT MIT was excreted in urine and 23 to 54% in feces after 24 hr. In the skin exposure experiment, 20 to 28% of CMIT MIT was excreted in the urine, whereas 1 to 2% of CMIT MIT was excreted in the feces. Thus, exposure to skin showed a much slower elimination rate as compared to oral exposure. According to the results of this experiment, no differences in the metabolic profile of CMIT MIT were observed when administered through different routes (91).
In another study, a skin absorption experiment using a blood sample from rabbits was performed. Occlusion patches were repeatedly treated with CMIT MIT, and blood was collected up to 55 hr after treatment. The results demonstrated no CMIT MIT in the blood (34).
Eight in vitro studies to analyze skin absorption rate of CMIT MIT were conducted. Rat skin exposed to CMIT MIT was extracted at several time intervals and rate of skin absorption was measured in a Franz diffusion cell. The amount of CMIT MIT that bound or passed through the skin was calculated. The skin absorption rate for CMIT MIT was calculated to be 99 and 117% at 3 and 6 hr, respectively. The maximum skin absorption rate after 48 to 96 hr was found to be 80% (92).

General description
Pharmaceutical secondary standard for applications in quality control, provides pharma laboratories and manufacturers with a convenient and cost-effective alternative to the preparation of in-house working standards.
CMIT/MIT is an isothiazolone biocide having a 3:1 ratio of CMIT and MIT, widely used for its broad-spectrum action against microbes, algae, and fungi. It is one of the active ingredients of humidifier disinfectants and a commonly used preservative in industrial products such as cosmetics, paints, adhesives and detergents.

Application
These Secondary Standards are qualified as Certified Reference Materials. These are suitable for use in several analytical applications including but not limited to pharma release testing, pharma method development for qualitative and quantitative analyses, food and beverage quality control testing, and other calibration requirements.

Analysis Note
These secondary standards offer multi-traceability to the USP, EP and BP primary standards, where they are available.

The mixture of 5-chloro-2-methylisothiazol-3(2H)-one (CMIT) and 2-methylisothiazol-3(2H)-one (MIT), CMIT/MIT, is a preservative in cosmetics. CMIT/MIT is a highly effective preservative; however, it is also a commonly known skin sensitizer. Therefore, in the present study, a risk assessment for safety management of CMIT/MIT was conducted on products containing 0.0015% of CMIT/MIT, which is the maximum MIT level allowed in current products. The no observed adverse effect level (NOAEL) for CMIT/MIT was 2.8 mg/kg bw/day obtained from a two-generation reproductive toxicity test, and the skin sensitization toxicity standard value for CMIT/MIT, or the no expected sensitization induction level (NESIL), was 1.25 μg/cm2/day in humans. According to a calculation of body exposure to cosmetics use, the systemic exposure dosage (SED) was calculated as 0.00423 mg/kg bw/day when leave-on and rinse-off products were considered. Additionally, the consumer exposure level (CEL) amounted to 0.77512 μg/cm2/day for all representative cosmetics and 0.00584 μg/cm2/day for rinse-off products only. As a result, the non-cancer margin of safety (MOS) was calculated as 633, and CMIT/MIT was determined to be safe when all representative cosmetics were evaluated. In addition, the skin sensitization acceptable exposure level (AEL)/CEL was calculated as 0.00538 for all representative cosmetics and 2.14225 for rinse-off products; thus, CMIT/MIT was considered a skin sensitizer when all representative cosmetics were evaluated. Current regulations indicate that CMIT/MIT can only be used at concentrations 0.0015% or less and is prohibited from use in other cosmetics products. According to the results of this risk assessment, the CMIT/MIT regulatory values currently used in cosmetics are evaluated as appropriate.

). Among isothiazolinone-based compounds, CMIT/MIT has been commonly used as a preservative since the early 1980s, owing to its high activity against microbial contaminants at very low concentrations and at a broad pH range (2–6).

Isothiazolinone-based compounds exert their antimicrobial activity via the reaction of their nitrogen (N)-sulfur (S) bonds with the thiol groups in the cell membranes of the target microorganisms (6). The oxidation of thiol groups causes formation of free radicals which can lead to cell death. In addition, these preservatives interfere with the Krebs cycle, which is associated with adenosine triphosphate (ATP) production, consequently inhibiting the microbial growth and metabolism (6).

Before 1989, CMIT/MIT, containing 1.5% active ingredients and sold under the trade name Kathon CG and, was primarily used as a preservative in cosmetics in a ratio of 3:1 (1). However, the first case of skin sensitization by cosmetics containing CMIT/MIT was reported in 1985 (7,8). Since then, several cases of skin allergy have been reported, identifying CMIT/MIT to be a common skin sensitizer (5,9–11). This resulted in lowering the concentration of CMIT/MIT to 0.0015% for both rinse-off products, such as shampoos, hair conditioners, shower gels, body wash, liquid soap, and surfactants, and leave-on products in 1989 in Europe (12). Similarly, in 1992, the limit was set to 0.0015% for rinse-off products and 0.00075% for leave-on products in the United States (13). Despite lowering the concentration limits of CMIT/MIT, the incidence rate of skin sensitization remained high and steady at 1 to 4% (14,15). At present, in Korea and Europe, the concentration of CMIT/MIT is limited to 0.0015% or less for rinse-off products (16,17).

Industrial compounds, including cosmetics, are routinely assessed and screened for their potential risks to ensure they meet the safety standards (18–22). In addition to risk assessment, studies on their toxicological profiles, alternative testing methods, as well as research on safety management and mechanism of action of cosmetic ingredients have been conducted (23–27). In the present study, we assessed the potential risk factors associated with CMIT/MIT to confirm its appropriateness for use as per the current safety standards for cosmetics. The risk assessment data used in the study included risk assessment guidelines; risk assessment methods; physical and chemical properties; regulatory values; toxicological data, absorption, distribution, metabolism, excretion (ADME) data; and skin absorption rate of CMIT/MIT. The approach used in the present study was based on the data published in the international journals and that recommended by the international cosmetic risk assessment agencies (e.g., Scientific Committee on Consumer Safety [SCCS], Cosmetic Ingredient Review [CIR], etc.). In addition, appropriate toxicity values and factors were selected through expert discussions to assess the potential risk factors associated with CMIT/MIT. Finally, based on the results of the risk assessment, we also evaluated the adequacy of current CMIT/MIT regulations.

COMMERCIAL USE
As mentioned above, CMIT/MIT is widely used as a preservative in cosmetics, paints, adhesives, detergents, and other industrial products. According to the European Union (EU) regulation, the permitted concentration limits of CMIT/MIT are up to 15 ppm in cosmetics, up to 15 ppm in paints, adhesives, and detergents, and over 5,000 ppm in industrial biocides (2,28). Among the cosmetics manufactured in Korea, 2,110 of the 100,190 products containing CMIT/MIT comprise rinse-off products, such as shampoos, rinses, and body washes (29).

HAZARD IDENTIFICATION
As part of the risk assessment, we evaluated the toxicological profile of CMIT/MIT; this included general toxicity, topical toxicity, developmental/reproductive toxicity, genotoxicity, carcinogenicity, phototoxicity, and toxicokinetics.

Subchronic toxicity
To evaluate the subchronic toxicity, rats were administered following CMIT MIT concentrations: 0, 40–80, 132–260, and 400–800 ppm for 90 days. No systemic toxicity was found to be associated with the treatment, and the NOEL was set at 800 ppm (29.1 a.i. mg/kg bw/day) (37). However, after rats were treated with 0, 25, 75, and 225 a.i. ppm CMIT MIT for 90 days, they showed irritation of the glandular stomach at 225 a.i. ppm. No histopathological changes were observed up to the highest concentration. As a result, the NOEL was set as 75 a.i. ppm, and the no observed adverse effect level (NOAEL) was set as 225 a.i. ppm (34,38). Three independent experiments in rats and dogs treated with CMIT MIT for approximately 3 months reported no treatment-related systemic toxicity (34,39,40). After dermal administration of CMIT MIT (0, 0.75, 3.75, and 18.75 mg/kg bw/day) in rats for 91 days, erythema, desquamation, edema, atonia, and eschar formation were observed in all treatment groups. Accordingly, the NOAEL was estimated to be below 0.104 a.i. mg/kg bw/day, and the lowest observed adverse effect level (LOAEL) was estimated to be 0.104 a.i. mg/kg bw/day or higher (41). No treatment-related systemic toxicity was observed in rabbits’ skin at 0, 100, 200, and 400 a.i. ppm after 13 weeks of treatment (34,42). In another experiment, rats exposed to 0, 0.34, 1.15, and 2.64 a.i. mg/m3 CMIT MIT demonstrated irritation of respiratory tract at 1.15 a.i. mg/m3, whereas no histopathological changes were observed up to the highest concentration. Therefore, the NOEL was set at 0.34 a.i. mg/m3, and the NOAEL was restricted to 2.64 a.i. mg/m3 (43) (Table 2).

Topical toxicity
Several skin sensitization tests using an occlusive patch were performed on rabbit skin. Treatment with CMIT MIT concentration of 1.1 to 14.2 a.i.% resulted in severe skin irritation. Results of another experiment at four different CMIT MIT concentrations revealed no irritation at 0.0056 a.i.%, moderate irritation at 0.28 a.i.%, and severe irritation at 0.56 and 5.6 a.i.% (34,44,45).

Furthermore, ocular experiments conducted in rabbits using CMIT MIT reported severe irritation at concentrations of 1.1 to 14 a.i.%. Results of another series of experiments performed using four CMIT MIT concentrations showed no irritation at concentrations from 0.056 to 0.01 a.i.%, weak to moderate irritation at 0.28 a.i.%, moderate to severe irritation from 0.56 to 1.7 a.i.%, and severe irritation from 2.8 to 5.6 a.i.%. In addition, cumulative irritation experiments performed in 12 rabbits using samples containing 0.0056 a.i.% CMIT MIT at a volume of 0.1 mL for 4 weeks revealed no irritation at 0.0056 a.i.% of CMIT MIT (34,46,47).

In another experiment, the bovine cornea was treated with CMIT MIT, MIT, or CMIT/1,2-benzisothiazolin-3-one (BIT) for 10 min to assess eye irritation (48). After the cornea was washed, it was placed in the complete minimum essential medium (cMEM) for more than 2 hr (48). Corneal permeability was measured using the fluorine dye solution to confirm the final turbidity (48). The in vitro score (IVS) was calculated by measuring the turbidity and absorbance, and evaluated by a predictive model designed by Gautheron et al (49). IVS refers to the intensity of the stimulation; an IVS of 3 or more indicates presence of an irritant (49). The MIT/BIT (21.8 ± 3.2) and CMIT MIT (16.8 ± 7.3) groups showed a stronger ocular stimulation than the MIT (9.3 ± 5.3) alone treatment group (48). Overall, these agents were considered to be mild eye irritants (48). In addition, a respiratory irritation experiment on rates determined the 50% respiratory rate decrease (RD50) to be 69 μg/L (9.4 a.i. μg/L) after a 407 μg/L CMIT MIT treatment (50).

Skin sensitization
To evaluate the effects of CMIT MIT on skin sensitization, the local lymph node assay (LLNA) was utilized. Results of this test revealed the effective concentration (EC3 (%)), i.e., the concentration at which the stimulation index of the test substance increases threefold or higher as compared to the control, to be 30 to 70 ppm (0.75 to 2 a.i. μg/cm2) after CMIT MIT treatment (51,52). In another study, the EC3 (%) was estimated to be 1.2 and 2.1 a.i. μg/cm2 (53,54). Based on these data, CMIT MIT was identified as an extreme skin sensitizer in animals.

A number of skin sensitization experiments have also been performed in humans. Cardin et al. (55) performed a repeated patch test to assess the effects of CMIT MIT in 1,450 individuals. Occlusive patches were induced thrice with CMIT MIT per week for 3 weeks and maintained for 24 hr. CMIT MIT was tested for a prototype concentration of 5 to 20 ppm and for various products. As a result, no skin sensitization was observed in products containing less than 12.5 ppm of CMIT MIT, and only one or two cases of skin sensitization occurred in shampoos containing 12.5 ppm and water containing 20 ppm (55).
An occlusive patch test was also performed in nine volunteers. A patch containing 1, 2, 5, 10, 15, 25, 50, and 100 ppm of CMIT MIT was applied on the volunteers for 48 hr. No skin reaction was observed at concentrations below 15 ppm. However, one patient treated with 25 ppm, six patients treated with 50 ppm, and nine patients treated with 100 ppm of CMIT MIT demonstrated a skin sensitization response. Accordingly, CMIT MIT was evaluated as a skin sensitizer at high treatment concentrations (56).

In another study, an occlusive patch test using an aqueous solution containing 25 ppm of CMIT MIT was performed in 18 volunteers. The patches were placed on patients for 24 hr, 3 times a week for 3 weeks. One volunteer showed a skin sensitization reaction. A skin sensitization response also appeared when the applicant was rechallenged 6 weeks later. Based on these results, investigators determined that 25 ppm of CMIT MIT could cause skin sensitization (34).
Based on a number of skin sensitization studies, the National Institute for Public Health and the Environment (RIVM) reported data comparing the mouse sensitization threshold by the LLNA test to the human sensitization threshold by the human sensitization test. In this report, the threshold for mice was set at 2.25 μg/cm2, whereas the threshold for humans was set at 1.25 μg/cm2 (57).

Developmental/reproductive toxicity
To determine the effects of CMIT MIT on reproductive ability, rats were administered 30, 100, and 300 a.i. ppm of CMIT MIT in drinking water. The control group was administered water and magnesium salt (Table 3). A total of 26 males and females were present in each group. The CMIT MIT concentrations were administered to two generations of rats at 0, 2.8–4.4, 8.5–11.8, and 22.7–28.0 a.i. mg/kg bw/day in the first parental generation (P1), and 0, 4.3–5.5, 13.4–16.0, and 35.7–39.1 a.i. mg/kg bw/day in the second parental generation (P2). In the P1 and P2, concentration-dependent histopathological changes were observed in the stomach. At concentrations of 100 and 300 a.i. ppm, erosion, hyperplasia, and hyperkeratosis were observed. When compared to the control group, neither the female estrus cycle in the P1 and P2 nor the male sperm motility, shape, and number were affected. Moreover, no differences in the other reproductive endpoints compared to the control group were observed. In both generations, gastric irritation was observed at medium and high concentrations; thus, the parental NOAEL of CMIT MIT was set at 30 ppm a.i. (P1: 2.8–4.4 mg/kg bw/day; P2: 4.3–5.5 mg/kg bw/day). The NOEL for reproductive toxicity was set at 300 ppm a.i. (P1: 22.7–28.0 mg/kg bw/day; P2: 35.7–39.1 mg/kg bw/day). No reproductive toxicity up to the highest concentration was noted (58).
In addition, CMIT MIT was administered via drinking water to 10 male and 10 female rats per group for 15 weeks at concentrations of 0, 25, 75, and 225 ppm. Following this, mating was performed within the same treatment group. No toxicity to parents and fetus was observed at 21 days after delivery (34).

Furthermore, oral administration experiments were performed in rats at 5 to 15 days of gestation. The experimental groups were treated with CMIT MIT concentrations of 1.5, 4.5, and 15 a.i. mg/kg bw/day, whereas the control group received distilled water. Twenty-five pregnant rats per group were selected in which the dose-dependent maternal toxicity was observed. One rat at low concentrations, two at medium concentrations, and three at high concentrations died due to wheezing, alopecia, and gastric irritation. No other reproductive or teratogenic toxicity was observed. Based on these results, a developmetal NOEL was selected at dose of greater than 15 mg/kg bw/day (59).
In addition, embryotoxic and fetotoxic effects were reported in rabbits at 6 to 18 days post-pregnancy. Fifteen rabbits per group were administered 0, 1.5, 4.4, and 13.3 a.i. mg/kg bw/day of CMIT MIT. This study reported that 0, 5, 12, and 14 rabbits per group, resepectively, were died at these concentrations due to development of ataxia, diarrhea, and severe gastric irritation. A decrease in the number of surviving fetuses, increase in the number of resorption sites, and loss at post-implantation stage were observed. No other treatment-related teratogenic toxicity was observed (34).
According to the data reported by SCCS (1), additional studies were conducted; however, no detailed information was provided (60–63).

Genotoxicity
A reverse mutation test (Ames test) using CMIT MIT was performed in Salmonella typhimurium. Numerous studies have reported CMIT MIT to mutate TA100 strain of S. typhimurium in the presence or absence of S9 (64–69). In addition, CMIT MIT is also known to mutate TA98, TA102, TA1535, and TA1537 strains of S. typhimurium (68), and has a negative response in E. coli (69).
A positive effect by CMIT MIT was observed in the gene mutation assay using mouse lymphoma cell line. The CMIT MIT treatment concentration range was selected as nontoxic to 10% relative growth. As a result, CMIT MIT increased mutant frequencies by up to 10 times (70–72).
Moreover, CMIT MIT did not induce an unscheduled DNA synthesis (UDS). In this experiment, primary hepatocytes from rats were treated with CMIT MIT at 0.00375 to 7.5 a.i. μg/mL for 20 hours. Cytotoxicity was observed only at concentrations above 0.75 a.i. μg/mL (72,73).

In vitro chromosomal aberration experiments using Chinese hamster lung fibroblasts were conducted where cells were treated with CMIT MIT at concentrations of 0.00045 to 0.12 a.i. μg/mL. Although toxicity was observed at 0.015 to 0.12 a.i. μg/mL, the number of chromosomal aberrations did not increase as compared to the control group (74).
A chromosome aberration test was also performed using the bone marrow cells of rats. Groups of five rats per group were administered 0, 0.28, 2.8, and 28 a.i. mg/kg bw/day of CMIT MIT for 5 consecutive days. In this study, CMIT MIT did not induce chromosomal changes (75).
In addition, a chromosome aberration test and a micronucleus assay were performed in mice, and a UDS study was performed in rats (76–83). These studies also did not induce genotoxicity.
A gender-linked recessive lethal test was performed in Drosophila melanogaster. The number of lethal cases in the progeny after oral and injection treatment was examined. No mutagenesis in the experimental animals was reported (72,84).
Several genotoxicity experiments showed positive in vitro results for CMIT MIT. However, the data published by the United States Environmental Protection Agency (U.S. EPA) consider the in vitro studies in the mammalian system to predict genotoxicity as inappropriate (13).

Carcinogenicity
According to the reported data, two types of carcinogenicity studies were performed for CMIT MIT. First, CMIT MIT was administered via drinking water to rats at concentrations of 30, 100, and 300 a.i. ppm for 2 years. The control group received water and magnesium salt. Ninety males and 80 females were present in each group. Blood and urine samples were evaluated at regular intervals throughout the study, and at the end of the experiment, histopathological examination was performed by autopsy. The survival rates at all doses in both male and female rats were found to be similar to those reported in the control group. No changes in physical, hematological, clinical chemistry, ophthalmological, or organ weight were observed during the duration of administration in any dose group. During the administration, no changes in body weight were observed in the dose groups, but a concentration-dependent decrease in water consumption was observed in the 30 a.i. ppm group (0–22%), the 100 a.i. ppm group (3–30%), and the 300 a.i. ppm group (15–40%). This was attributed to the unpleasant taste of CMIT MIT, not the salt, which acted as a drug stabilizer. No evidence of treatment-related neoplasms or systemic toxicity was observed, ruling out CMIT MIT to be a carcinogen. Based on the observed gastric irritation in the stomach at 100 a.i. ppm and 300 a.i. ppm, the NOEL and NOAEL were determined to be 30 a.i. ppm and 300 a.i. ppm, respectively (85).

Dermal carcinogenicity studies were also conducted in mice for 30 months. Mice were administered 0 and 400 a.i. ppm of CMIT MIT, and 1,000 a.i. ppm of 3-methylcholanthrene was selected as the positive control. Each treatment group consisted of 40 mice. CMIT MIT was mixed with distilled water to obtain a total volume of 25 μL and administered to the shaved dorsal skin of mice. At the end of this experiment, all animals were autopsied and histopathologically analyzed. All positive control groups died within 16 months due to development of squamous cell carcinoma of the skin that metastasized to the lungs, kidneys, and spleen. Focal hyperplasia and dermal inflammation were observed in the CMIT MIT treatment group; however, no treatment-related neoplasms were observed. No other histopathological adverse effects on tissues and organs were reported. Based on these results, CMIT MIT was found to be a non-carcinogenic compound (86).

SUMMARY AND CONCLUSION
In the present study, we performed a risk assessment of CMIT/MIT, a widely used preservative in cosmetic industry, to confirm its appropriateness for use as per the current safety standards. The results of the non-cancer toxicity assessment in a two-generation reproductive toxicity test revealed an NOAEL of 2.8 mg/kg bw/day, whereas the skin sensitization toxicity test determined the NESIL to be 1.25 μg/cm2/day for humans (57,58). When considering of all types of cosmetics, the MOS of non-cancer risk assessment was over 100; however, the AEL/CEL ratio of skin sensitization risk assessment was less than 1, indicating skin sensitization could be a possibility. The AEL/CEL ratio of skin sensitization was calculated to be 2.14225 for rinse-off cosmetics, indicating absence of any dermal risk. In addition, the results of the risk assessment were compared to those of the international risk assessment agency. SCCS (1) selected the NOAEL as 2.8 mg/kg bw/day for the CMIT/MIT according to the two-generation reproductive toxicity study in rats. In addition, after evaluating daily rinse-off products containing 0.0015% of CMIT/MIT, the MOS was calculated to be 7,368, and no safety concern was determined (1). In addition, the RIVM (57) recommends a quantitative risk assessment of skin sensitizers as a method to ensure safety against skin sensitization. A risk assessment for skin sensitization was performed on 2 to 15 ppm of CMIT/MIT in body shampoo/gel, liquid soap, bubble bath, body lotion/cream, shampoo, and eau de toilette. According to the results, the skin sensitization AEL/CEL of the eau de toilette was calculated to be 0.005, which the RIVM (57) considered a safety concern. The CIR did not perform a quantitative risk assessment; however, CMIT/MIT was evaluated as safe at concentrations of 15 ppm for rinse-off products and 7.5 ppm for leave-on products based on the cumulative patch test for humans (13,95).

At present, CMIT/MIT is widely used as a preservative for cosmetics in Korea and Europe (16,17). In addition, CMIT/MIT serves as a raw material in rinse-off products at a concentration below 0.0015%; however, its use is prohibited in other products (16,17). Based on the results of the risk assessment performed in the present study, the current CMIT/MIT regulatory values used in the cosmetics industry are evaluated as appropriate.