title: Recent increase in allergic reactions to methylchloroisothiazolinone/methylisothiazolinone: is methylisothiazolinone the culprit?
abstract: BACKGROUND
  The frequency of sensitization to methylchloroisothiazolinone (MCI)/ methylisothiazolinone (MI) observed in the Information Network of Departments of Dermatology (IVDK) was constantly around 2.1% from 1998 to 2009. After that, it increased to 3.9% in 2011, paralleled by an increase in the frequency of allergic reactions to MI in the preservative series from 1.9% in 2009 to 4.4% in 2011. MI without MCI has increasingly been used as a preservative in cosmetics and skin care products in recent years.
  
  
  OBJECTIVE
  To epidemiologically investigate the possible reasons for this development and to analyse concomitant reactions to MCI/MI and MI.
  
  
  METHODS
  A retrospective analysis of IVDK data from 2009 to 2011 was performed.
  
  
  RESULTS
  Stratified data analysis revealed pronounced increases in reactivity to MCI/MI and MI in females, face dermatitis patients, and patients tested because of suspected cosmetic intolerance. The proportion of MI-positive patients among those reacting to MCI/MI increased from 43% to 59% between 2009 and 2011.
  
  
  CONCLUSIONS
  More widespread consumer exposure has most likely led to the increase in primary sensitization to MI and subsequently to a rise in MCI/MI reactions resulting from immunological cross-reactions. A reduction in the maximum use concentration of MI seems advisable. MI should be patch tested in the baseline series.
authors.affiliation: Information Network of Departments of Dermatology, University of Göttingen, 37075 Göttingen, Germany. jgeier@gwdg.de
authors.forename: Johannes
authors.initials: J
authors.lastname: Geier
authors.forename: Holger
authors.initials: H
authors.lastname: Lessmann
authors.forename: Axel
authors.initials: A
authors.lastname: Schnuch
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Uter
mesh_terms: D003358:Cosmetics / Q000633:toxicity*; D017449:Dermatitis, Allergic Contact / Q000453:epidemiology / Q000209:etiology*; D004202:Disinfectants / Q000633:toxicity*; D005260:Female; D005858:Germany; D006801:Humans; D008297:Male; D010328:Patch Tests; D011310:Preservatives, Pharmaceutical / Q000633:toxicity; D015995:Prevalence; D012189:Retrospective Studies; D013844:Thiazoles / Q000633:toxicity*
chemical_list: D003358:Cosmetics; D004202:Disinfectants; D011310:Preservatives, Pharmaceutical; D013844:Thiazoles; C011506:2-methyl-4-isothiazolin-3-one; C011421:5-chloro-2-methyl-4-isothiazolin-3-one