Sensitization to Methylisothiazolinone in a group of Methylchloroisothiazolinone/Methylisothiazolinone allergic Patients

Abstract

In the EU, Methylisothiazolinone (MI) was approved as a preservative in cosmetics and household products in 2005. Since then, several cases of MI contact allergy have been reported. We studied the prevalence of MI sensitization in patients allergic to Methylchloroisothiazolinone/Methylisothiazolinone (MCI/MI). From a total of 751 patients submitted to patch testing between 2007 and 2011, 26 were sensitized to MCI/MI 100 ppm aq. Fifteen patients were retested with MCI/MI 100 ppm aq, MI 200 ppm aq and personal products, and the relevance of positive results, concerning the use of personal products, was evaluated. Seven of the 15 MCI/MI positive patients were positive to MI: six patients showed an equally intense reaction to MCI/MI and MI alone, and another one presented with a stronger reaction to the latter compound. All positive reactions were relevant. The use of MI alone as a preservative does not seem to be a safe alternative. In this study, the majority of positive reactions to MCI/MI and MI had similar intensity, although primary sensitization to MI has to be considered according to each individual case; moreover, primary sensitization to MCI with cross-reactivity to MI cannot be excluded. Further studies are needed to determine the optimal concentration for MI patch testing.

Allergic contact dermatitis to methylisothiazolinone: Exposure from baby wipes causing hand dermatitis

“…This reinforces the need to test for MI alone in standard patch testing, as only 79% of the patients who reacted to MI also reacted to MCI/MI, and only 65% of patients who reacted to MCI/MI also reacted to MI. This finding has been confirmed in a recent study . Testing MI as a sole allergen detects the relevant allergy missed by testing the MCI/MI mix, thus its presence in the current baseline series.…”

“…It was recently reported that 23% of cosmetics and 28% of detergents contained isothiazolinones . Several European studies in the 18 months prior to the time of writing have shown that MI alone is an emerging cause of ACD in both cosmetic and industrial settings …”

AllerGenie in a Bottle

“…It was also revealed that the concentration (25 ppm) of MI in Kathon CG found in most patch test panels was suboptimal for detecting sensitization, missing up to 40% of allergic cases. [1][2][3] Common sources of exposure to MI include baby products, deodorants, hair care and coloring products, makeup, nail care products, shaving products, and sunscreens. 1 Occupational sources include cutting oils, glues, house paints, inks, lacquers, and varnishes.…”

“…1 Relevant to our patient, growingly popular "green" household cleaning products may contain MI. 1,3 Contact allergy to MI may present as dermatitis of the hands, face, and perianal area. 4 A retrospective review by the North American Contact Dermatitis Group in more than 4000 patients showed a 2.5% positive patch-test reaction rate to MI/MCI.…”

“…However, case reports and registries documented the increasingly high prevalence of MI as a sensitizer. It was also revealed that the concentration (25 ppm) of MI in Kathon CG found in most patch test panels was suboptimal for detecting sensitization, missing up to 40% of allergic cases 1–3 …”