title: p-Phenylenediamine sensitization is more prevalent in central and southern European patch test centres than in Scandinavian: results from a multicentre study.
abstract: BACKGROUND
  Positive patch test reactions to p-phenylenediamine (PPD) are common. PPD is used in oxidative hair dyes and is also present in dark henna temporary 'tattoos'. Cross-sensitization to other contact allergens may occur. Because subjects sensitized to PPD are at risk of clinically severe reactions upon hair dyeing, there is a need for 'current' prevalence data on PPD sensitization.
  
  
  OBJECTIVE
  To compare PPD patch test results from dermatitis patients tested between 2003 and 2007 in 10 European patch test centres and to analyse the causes and determine relevance of positive PPD patch test reactions.
  
  
  METHODS
  Patch testing was performed using PPD (1% free base in petrolatum from Trolab (Almirall Hermal GmbH, Reinbeck, Germany) or Chemotechnique (Malmö, Sweden), equivalent to 0.090 mg/cm(2) in the TRUE test from MEKOS Laboratories AS). Statistical analysis was performed using the chi-squared test.
  
  
  RESULTS
  The weighted average prevalence was 4.6% among 21 515 patients. PPD sensitization occurred more often in centres located in Central and Southern Europe than in Scandinavian centres (odds ratio = 2.40; 95% confidence interval = 2.07-2.78). The overall proportion of positive patch test reactions to PPD that were registered as being of either current or 'past' relevance was high (weighted average 53.6% and 20.3%, respectively). Consumer hair dyeing was the most prominent cause of PPD sensitization (weighted average 41.8%). Furthermore, occupational hair dye exposure (10.6%) and cross-sensitization to textile dyes (12.6%) were frequently reported.
  
  
  CONCLUSIONS
  PPD sensitization caused by exposure to hair dyes is frequent and remains a present problem for patients visiting contact dermatitis clinics, especially in patch test centres located in Central and Southern Europe.
authors.affiliation: National Allergy Research Centre, Department of Dermato-Allergology, Gentofte Hospital, University of Copenhagen, DK-2900 Hellerup, Denmark. jacpth01@geh.regionh.dk
authors.forename: Jacob Pontoppidan
authors.initials: JP
authors.lastname: Thyssen
authors.forename: Klaus Ejner
authors.initials: KE
authors.lastname: Andersen
authors.forename: Magnus
authors.initials: M
authors.lastname: Bruze
authors.forename: Thomas
authors.initials: T
authors.lastname: Diepgen
authors.forename: Ana M
authors.initials: AM
authors.lastname: Giménez-Arnau
authors.forename: Margarida
authors.initials: M
authors.lastname: Gonçalo
authors.forename: An
authors.initials: A
authors.lastname: Goossens
authors.forename: Christophe
authors.initials: C
authors.lastname: Le Coz
authors.forename: John
authors.initials: J
authors.lastname: McFadden
authors.forename: Thomas
authors.initials: T
authors.lastname: Rustemeyer
authors.forename: Ian R
authors.initials: IR
authors.lastname: White
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: White
authors.forename: Jeanne Duus
authors.initials: JD
authors.lastname: Johansen
mesh_terms: D000328:Adult; D000485:Allergens / Q000009:adverse effects; D004396:Coloring Agents / Q000009:adverse effects*; D017449:Dermatitis, Allergic Contact / Q000175:diagnosis / Q000453:epidemiology*; D009783:Dermatitis, Occupational / Q000453:epidemiology; D005060:Europe; D005260:Female; D006202:Hair Dyes / Q000009:adverse effects / Q000737:chemistry; D006801:Humans; D008297:Male; D010328:Patch Tests; D010655:Phenylenediamines / Q000009:adverse effects*; D015995:Prevalence; D012537:Scandinavian and Nordic Countries
chemical_list: D000485:Allergens; D004396:Coloring Agents; D006202:Hair Dyes; D010655:Phenylenediamines; C029728:4-phenylenediamine