title: Sensitization to palladium in Europe.
abstract: BACKGROUND
  Recently, sodium tetrachloropalladate (Na2 PdCl4 ) was found to be a more sensitive palladium patch test allergen than palladium dichloride (PdCl2 ).
  
  
  OBJECTIVE
  To determine the optimal test concentration of Na2 PdCl4 , to evaluate the prevalence of palladium sensitization with Na2 PdCl4 and PdCl2 , and to compare the results with nickel sensitization in a European multicentre study.
  
  
  METHODS
  In addition to the European or national baseline series including NiSO4 ·6H2 0 5% pet., consecutive patients were tested with PdCl2 and Na2 PdCl4 2%, 3% and 4% pet. in eight European dermatology clinics. The age and sex distributions were also evaluated in patients sensitized to nickel and palladium.
  
  
  RESULTS
  In total, 1651 patients were tested. Relative to 3% Na2 PdCl4 , 4% Na2 PdCl4 did not add any information. Two per cent Na2 PdCl4 resulted in more doubtful reactions and showed suboptimal reactivity. The prevalence of palladium sensitization doubled with Na2 PdCl4 and was similar to that of nickel. Interestingly, in contrast to nickel sensitization, palladium sensitization was not related to female sex.
  
  
  CONCLUSIONS
  Three per cent Na2 PdCl4 pet. is the most suitable patch test concentration. Sensitization to palladium is almost as prevalent as sensitization to nickel. The sex distribution is different between nickel-sensitized and palladium-sensitized patients, suggesting different sources of exposure.
authors.affiliation: Department of Dental Materials Science, Academic Centre for Dentistry Amsterdam, University of Amsterdam and VU University Amsterdam, Gustav Mahlerlaan 3004, 1081 LA, Amsterdam, The Netherlands.
authors.forename: Joris
authors.initials: J
authors.lastname: Muris
authors.forename: An
authors.initials: A
authors.lastname: Goossens
authors.forename: Margarida
authors.initials: M
authors.lastname: Gonçalo
authors.forename: Andreas J
authors.initials: AJ
authors.lastname: Bircher
authors.forename: Ana
authors.initials: A
authors.lastname: Giménez-Arnau
authors.forename: Caterina
authors.initials: C
authors.lastname: Foti
authors.forename: Magnus
authors.initials: M
authors.lastname: Bruze
authors.forename: Klaus Ejner
authors.initials: KE
authors.lastname: Andersen
authors.forename: Thomas
authors.initials: T
authors.lastname: Rustemeyer
authors.forename: Albert J
authors.initials: AJ
authors.lastname: Feilzer
authors.forename: Cornelis J
authors.initials: CJ
authors.lastname: Kleverlaan
mesh_terms: D017677:Age Distribution; D000485:Allergens / Q000008:administration & dosage; D003429:Cross Reactions; D017449:Dermatitis, Allergic Contact / Q000175:diagnosis* / Q000453:epidemiology / Q000209:etiology; D005060:Europe / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009532:Nickel / Q000009:adverse effects; D010165:Palladium / Q000008:administration & dosage / Q000009:adverse effects; D010328:Patch Tests / Q000379:methods*; D015995:Prevalence; D017678:Sex Distribution
chemical_list: D000485:Allergens; C030174:tetrachloropalladium; D010165:Palladium; D009532:Nickel; C008756:palladium chloride
keywords: allergic contact dermatitis; cross-reactivity; epidemiology; metals; nickel; oral disease; palladium