title: Patch testing with 2.0% (0.60 mg/cm 2) formaldehyde instead of 1.0% (0.30 mg/cm 2) detects significantly more contact allergy.
abstract: BACKGROUND
  The currently used patch test concentration for formaldehyde is 1.0% (wt/vol) in water. However, clinical experience and previous studies suggest that 1.0% might be insufficient for detecting an optimized number of clinically relevant cases of contact allergy to formaldehyde.
  
  
  OBJECTIVE
  To validate earlier patch test results for comparison of 1% (wt/vol) and 2% (wt/vol) formaldehyde in water, and to investigate co-reactivity with quaternium-15.
  
  
  METHODS
  In 12 dermatology clinics, 3591 patients were routinely patch tested simultaneously with 2.0% (wt/vol) (0.60 mg/cm(2)) and 1.0% (wt/vol) (0.30 mg/cm(2)) formaldehyde. Micropipettes were used for delivering the exact dosage of the allergen.
  
  
  RESULTS
  Significantly more patients reacted to 2.0% formaldehyde than to 1.0% (3.4% versus 1.8%, p < 0.001). Overall, there were no sex differences between those reacting positively to 2.0% and 1.0%. Of 25 quaternium-15-positive patients, 4 (0.1%) reacted positively without reacting to formaldehyde.
  
  
  CONCLUSIONS
  On the basis of the results of this multicentre study, as well as of previous studies, it can be suggested that 2.0% (wt/vol) in water formaldehyde should be used in routine patch testing in the baseline series.
authors.affiliation: Department of Occupational and Environmental Dermatology, Skåne University Hospital, Lund University, 205 02 Malmö, Sweden. ann.ponten@med.lu.se
authors.forename: Ann
authors.initials: A
authors.lastname: Pontén
authors.forename: Kristiina
authors.initials: K
authors.lastname: Aalto-Korte
authors.forename: Tove
authors.initials: T
authors.lastname: Agner
authors.forename: Klaus E
authors.initials: KE
authors.lastname: Andersen
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: Jeanne D
authors.initials: JD
authors.lastname: Johansen
authors.forename: Christophe J
authors.initials: CJ
authors.lastname: Le Coz
authors.forename: Howard I
authors.initials: HI
authors.lastname: Maibach
authors.forename: Thomas
authors.initials: T
authors.lastname: Rustemeyer
authors.forename: Ian R
authors.initials: IR
authors.lastname: White
authors.forename: Magnus
authors.initials: M
authors.lastname: Bruze
mesh_terms: D000485:Allergens / Q000008:administration & dosage*; D017449:Dermatitis, Allergic Contact / Q000175:diagnosis*; D005260:Female; D005557:Formaldehyde / Q000008:administration & dosage*; D006801:Humans; D008297:Male; D008709:Methenamine / Q000008:administration & dosage / Q000031:analogs & derivatives; D010328:Patch Tests / Q000379:methods*; D012996:Solutions; D014867:Water
chemical_list: D000485:Allergens; D012996:Solutions; D014867:Water; D005557:Formaldehyde; C018375:quaternium-15; D008709:Methenamine