Methylisothiazolinone in baby wipes: a rising star among causes of contact dermatitis
To the Editor: Methylisothia-zolinone (MI) is a preservative that has been used alone in cosmetic and personal products since the early 2000s.1 Before that time, MI was combined with methylchloroiso-thiazolinone in the widely used preservative Kathon CG (Dow Chemical Company), in a 1:3 ratio with the concentration of MI limited to 3.75 parts per million. This limit was subsequently increased to 100 parts per million, and MI is now being widely used in consumer products.
MI has been included in our baseline patch test series since 2011, following European reports of an increasing prevalence of MI allergy.1 We have subsequently seen a rapid increase in the number of patients with contact allergy to MI. Our rate of positive reactions on MI patch tests to November 2013 was 11.3% (40 patients who had relevant reactions of a total 353), compared with a rate of 3.5% (15/428) in 2011 and 8.4% (38/454) in 2012. MI is now the most common cause of allergic contact dermatitis in our patient population.