The dramatic increase in the rate of methylisothiazolinone contact allergy in <scp>B</scp>elgium: a multicentre study

TLDR

Contact allergy to methylisothiazolinone is rapidly rising across Europe, and safer concentrations for rinse‑off products must be defined despite recent bans on leave‑on cosmetics. This multicentre study reports on MCI/MI and MI sensitization rates in Belgium and stresses the need for ongoing monitoring and inclusion of high test concentrations in baseline series. Retrospective chart review of 6 599 patients from 2010‑2012, plus 2 081 patients from 2013, using a standardized questionnaire assessed MCI/MI and MI sensitization. MI sensitization increased from 6.0 % in 2012 to 7.2 % in 2013, predominantly affecting women (median age 49) with hand or facial dermatitis from cosmetics, and concurrent reactions to octylisothiazolinone were noted.

Abstract

Summary Background The rate of contact allergy and allergic contact dermatitis caused by methylisothiazolinone ( MI ) is dramatically increasing throughout E urope. Objectives To report on methylchloroisothiazolinone ( MCI )/ MI and MI allergy in B elgium. Patients and methods Between J anuary 2010 and D ecember 2012, the medical charts of 6599 patients of the B elgian C ontact and E nvironmental D ermatitis G roup were retrospectively reviewed for MCI / MI and MI sensitization by use of a standardized questionnaire. Available data on sensitization in 2081 patients tested in 2013 were also included. Results In 2012, the sensitization rate for MCI / MI had increased to 4.5% and that for MI to 6.0%; the latter showed a further increase to 7.2% in 2013. The people mainly affected were women with a median age of 49 years with hand and/or facial dermatitis, most often resulting from the use of cosmetics. Simultaneous reactions to octylisothiazolinone were observed. Conclusion A dramatic increase in the rate of contact allergy caused by MI in cosmetics is occurring in B elgium. Notwithstanding the recent recommendation to discontinue the use of MI in leave‐on cosmetics, safer use concentrations should also be determined for rinse‐off products. Close monitoring of MI sensitization in the near future will be necessary, and the highest test concentrations reported for MI and MCI / MI should be included in the baseline series.