title: Methylchloroisothiazolinone/methylisothiazolinone and methylisothiazolinone allergies can be detected by 200 ppm of methylchloroisothiazolinone/methylisothiazolinone patch test concentration.
abstract: BACKGROUND
  Methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) and methylisothiazolinone (MI) contact allergies are rising dramatically. Moreover, 100 ppm of MCI/MI patch test might not detect an important number of MCI/MI and MI allergies.
  
  
  OBJECTIVE
  This study aimed to present the prevalence of contact allergy to both preservatives in an area of Spain and to investigate if 100 ppm of MCI/MI is an adequate concentration for a proper diagnosis.
  
  
  METHODS
  A prospective study was conducted from October 2011 to September 2013. All patients were patch tested with the Spanish baseline series (containing 100 ppm of MCI/MI) and with 200 ppm of MCI/MI and 2000 ppm of MI.
  
  
  RESULTS
  A total of 490 patients were patch tested. The MCI/MI prevalence was 10% and increased from 7.8% in last term of 2011 to 14.3% in the first 9 months of 2013. The MI prevalence was 4.5% and increased from 1% to 7.7% in the same period. One hundred parts per million of MCI/MI could not diagnose 24.5% of MCI/MI allergies. All MI allergies were detected by 200 ppm of MCI/MI, whereas only 68.2% were positive to 100-ppm concentration.
  
  
  CONCLUSIONS
  For a correct diagnosis of MCI/MI and MI contact allergies, we advocate increasing the MCI/MI patch test concentration to 200 ppm along with a temporal inclusion of MI in the North American Contact Dermatitis Group baseline series.
authors.affiliation: From the Dermatology Department, Hospital General Universitario de Alicante, Spain.
authors.forename: Maria
authors.initials: M
authors.lastname: Leiva-Salinas
authors.forename: Laura
authors.initials: L
authors.lastname: Frances
authors.forename: Irene
authors.initials: I
authors.lastname: Marin-Cabanas
authors.forename: Angelica Maria
authors.initials: AM
authors.lastname: Bouret
authors.forename: Juan Francisco
authors.initials: JF
authors.lastname: Silvestre
mesh_terms: D000328:Adult; D015984:Causality; D003358:Cosmetics / Q000009:adverse effects; D017449:Dermatitis, Allergic Contact / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology; D009783:Dermatitis, Occupational / Q000175:diagnosis* / Q000453:epidemiology / Q000209:etiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010328:Patch Tests / Q000706:statistics & numerical data; D011310:Preservatives, Pharmaceutical / Q000009:adverse effects; D015995:Prevalence; D011446:Prospective Studies; D013030:Spain; D013844:Thiazoles / Q000009:adverse effects*; D055815:Young Adult
chemical_list: D003358:Cosmetics; D011310:Preservatives, Pharmaceutical; D013844:Thiazoles; C011506:2-methyl-4-isothiazolin-3-one; C011421:5-chloro-2-methyl-4-isothiazolin-3-one