Background
The preservative methylisothiazolinone (MI) is used in combination with methylchloroisothiazolinone (MCI), but the MCI/MI mixture has been identified as highly allergenic. MI is considered to be less allergenic, and since the mid‐2000s has been widely used alone, but is now clearly identified as a contact allergen. The French Vigilance Network for Dermatology and Allergy of the Study and Research Group on Contact Dermatitis (REVIDAL‐GERDA) added MI to its baseline patch testing series in 2010.
Objective
To evaluate the change in the proportion of MI‐positive tests in France between 2010 and 2012.
Patients/materials/methods
We conducted a nationwide, multicentre, retrospective study of all MI‐tested patients between 2010 and 2012.
Results
Sixteen centres participated in the study (7874 patients were tested). Patch tests were performed mainly at a concentration of MI 200 ppm aq. We observed a significant increase in the proportion of MI‐positive tests in 2012 and 2011 as compared with 2010 (5.6%, 3.3%, and 1.5%, respectively; p < 0.001).
Conclusions
We report a significant increase in the number of MI‐positive tests. MI is confirmed to be a rapidly emerging allergen, as also observed in other European countries.