title: Nickel allergy and its relationship with local nickel pollution, ear piercing, and atopic dermatitis: a population-based study from Norway.
abstract: BACKGROUND
  The north-Norwegian population of Sør-Varanger lives close to 2 Russian nickel smelters.
  
  
  OBJECTIVE
  We studied the importance of the local nickel pollution, as well as ear piercing and atopic dermatitis, on the prevalence of nickel allergy in Sør-Varanger.
  
  
  METHODS
  We patch-tested 1767 adults who were randomly selected from 2 different cross-sectional studies; in Sør-Varanger and the reference city of Tromsø, which has no nickel-polluting industry.
  
  
  RESULTS
  Nickel allergy was diagnosed in 27.5% and 31.1% of the women in Sør-Varanger and Tromsø, respectively, and in 5.1% and 5.0% of the men. In women, ear piercing was a strong risk factor (relative risk = 3.30; 95% confidence interval = 2.01 to 5.43). A history of atopic dermatitis was not associated with nickel sensitization. We found no increased risk of nickel allergy in Sør-Varanger compared with Tromsø in adjusted multivariate analyses.
  
  
  CONCLUSIONS
  The high prevalence of nickel allergy found in Sør-Varanger could not be attributed to pollution from the nearby nickel industry.
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000395:Air Pollutants, Occupational / Q000009:adverse effects*; D016001:Confidence Intervals; D003430:Cross-Sectional Studies; D017449:Dermatitis, Allergic Contact / Q000453:epidemiology*; D003876:Dermatitis, Atopic / Q000453:epidemiology*; D004431:Ear, External; D005260:Female; D006801:Humans; D008297:Male; D008669:Metallurgy; D008875:Middle Aged; D015999:Multivariate Analysis; D009532:Nickel / Q000009:adverse effects*; D009664:Norway / Q000453:epidemiology; D010328:Patch Tests; D011159:Population Surveillance; D015995:Prevalence; D011677:Punctures / Q000009:adverse effects*; D012307:Risk Factors; D012737:Sex Factors