What is MIT?
Methylisothiazolinone or MIT or MI, sometimes erroneously called methylisothiazoline, is a powerful biocide and preservative within the group of isothiazolinones, used in personal care products. Methylisothiazolinone and other isothiazolinone-derived biocides are utilized 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 (chloromethylisothiazolinone or CMIT) and 2-methyl-4-isothiazolin-3-one (methylisothiazolinone or MIT), which are the active ingredients in a 3:1 mixture (CMIT:MIT) sold commercially as Kathon. Kathon is supplied to manufacturers as a concentrated stock solution containing from 10-15% of CMIT/MIT. For applications the recommended use level is from 6 ppm to 75 ppm active isothiazolones
What is BENZ 3?
Benzophenone-3 (Oxybenzone) and Benzophenone-4 (Sulisobenzone) are chemical UV absorbers solid (powder) at normal temperature. Both cover UVB and short UVA (UVA-2) range but are relatively weak sunscreens, inadequate when used alone. They are both very stable and protect and augment other UV absorbers. Benzophenones are absorbed into the skin and have been shown in some studies to promote generation of potentially harmful free radicals. the shelf life of paints, varnishes, and other industrial products, benzophenones were added to sunscreens in the 1950s. Other personal care products that may contain benzophenones are hair dyes, perfumes, shampoos, detergent bars, and nail polishes. The agents are still used in number of industrial applications, including plastic lens filters for color photography, aerosol sprays to protect color prints, and transparent shades to protect window displays.
(CMIT:MIT) sold commercially as Kathon. Kathon is supplied to manufacturers as a concentrated stock solution containing from 10-15% of CMIT/MIT. For applications the recommended use level is from 6 ppm to 75 ppm active isothiazolones
Benzophenones named 2014 Contact Allergen of the Year
By: DOUG BRUNK, Family Practice News Digital Network
MARCH 14, 2014
Benzophenones, chemical ultraviolet light absorbers used in products ranging from sunscreens and hair sprays to plastic lens filters for color photography, have been named the American Contact Dermatitis Society’s 2014 Contact Allergen of the Year.
First used as a preserver to extend the shelf life of paints, varnishes, and other industrial products, benzophenones were added to sunscreens in the 1950s. Other personal care products that may contain benzophenones are hair dyes, perfumes, shampoos, detergent bars, and nail polishes. The agents are still used in number of industrial applications, including plastic lens filters for color photography, aerosol sprays to protect color prints, and transparent shades to protect window displays. According to a feature article in the January/February 2014 issue of the journal Dermatitis, benzophenones-3, -4, -8, and -10 rank as the four agents most commonly used in personal care products. In addition, the amount of benzophenone-3 used in United States sunscreens is more than all other benzophenones combined (Dermatitis 2014;25:3-10).
In an interview, coauthor Erin M. Warshaw, chief of dermatology at the Minneapolis Veterans Affairs Medical Center, said that benzophenones were chosen as Allergen of the Year "to raise awareness that they are becoming more of a common allergen, and [to recommend] that they should be on a standard screening series, because they’re in so many products like sunscreen, shampoo, conditioner, perfumes, and hand sanitizers. If you’re not thinking about sunscreen [as a potential allergen], you’ll miss it," Dr. Warshaw said.Today, benzophenone-3 "is not only the most common benzophenone to cause positive patch test reactions, but it also is the most common UV filter, overall, to cause allergy," wrote lead author Ashley R. Heurung, a fourth-year student at the University of Minnesota, Minneapolis, and her associates. "The most recent 10-year retrospective analysis of the North American Contact Dermatitis Group Data (NACDG; 2001-2010) found that of the 219 of 23,908 patch-tested patients with sunscreen listed as an allergen source, 70.2% had positive patch test reactions to benzophenone-3" (Dermatitis 2013;24:176-82).
The American Contact Dermatitis Society’s Core Screening Series includes benzophenones, "but most dermatologists use T.R.U.E Test, a prepackaged kit of 36 allergens," Dr. Warshaw noted. "Benzophenones are not on that series."
Reports of contact dermatitis triggered by benzophenone-4 have appeared in recent medical literature, but data regarding adverse reactions of benzophenones-8 and -10 are scarce. The authors noted that benzophenone-3 is the culprit in more photoallergic contact dermatitis reactions than any other UV filter available, although large photopatch studies have shown that benzophenone-4 is a leading cause of photoallergy in patients with adverse reactions to sunscreens. Benzophenones-10 and -2 also have been implicated in photopatch reaction tests, but no reports of photoallergy to benzophenone-8 have been documented.
The authors added that benzophenone-3 shows high rates of cross-reactivity with octocrylene and ketoprofen, and that at least two cases of anaphylaxis from topical application of benzophenone-3 have been published (J. Allergy Clin. Immunol. 2001;107:556-7 and Contact Dermatitis 2002;46:55-6). "Both cases resulted in generalized wheal and flare reactions and syncope after widespread application of a sunscreen or sunless tanning product with this filter," they wrote. "Contact urticaria developed after more limited exposure to benzophenone-3 in both cases."
The authors stated that they had relevant conflicts to disclose.