title: Trend of contact allergy to cosmetic ingredients in Thais over a period of 10 years.
abstract: BACKGROUND
  Contact allergy to cosmetic ingredients is common. However, there are no recent comprehensive studies on contact allergy to cosmetic ingredients in Asia.
  
  
  OBJECTIVE
  To identify positive patch test reactions in patients tested at Siriraj Hospital, Bangkok, Thailand to allergens present in cosmetics.
  
  
  METHODS
  A retrospective review of medical records from the outpatient contact dermatitis clinic was conducted from January 1999 to December 2008. Patients with at least one positive patch test reaction to allergens associated with cosmetic ingredients were studied. The results were evaluated using Pearson's χ(2) -test with Yates' continuity correction or Fisher's exact test where appropriate,and a p-value <0.002 was considered to be statistically significant by Bonferroni correction.
  
  
  RESULTS
  There were 1247 cases (239 males and 1008 females; mean age 38.5 years). Fragrance chemicals and preservatives were the most commonly recognized cosmetic allergens. Ammoniated mercury was the only allergen that showed a significantly increased frequency over the 10-year period (p = 0.0008).
  
  
  CONCLUSIONS
  Our study showed that ammoniated mercury is an emerging cosmetic allergen, showing an increased prevalence in recent years in Thailand. A focus is required on emerging cosmetic allergens and what may account for the upward trend of cosmetic contact dermatitis.
authors.affiliation: Department of Dermatology, Mahidol University, Bangkok 10700, Thailand. wboonchai@yahoo.com
authors.forename: Waranya
authors.initials: W
authors.lastname: Boonchai
authors.forename: Rasthawathana
authors.initials: R
authors.lastname: Desomchoke
authors.forename: Pacharee
authors.initials: P
authors.lastname: Iamtharachai
mesh_terms: D000328:Adult; D000485:Allergens / Q000009:adverse effects*; D000641:Ammonia / Q000009:adverse effects*; D016009:Chi-Square Distribution; D003358:Cosmetics / Q000009:adverse effects*; D017449:Dermatitis, Allergic Contact / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008297:Male; D008627:Mercuric Chloride / Q000009:adverse effects*; D008875:Middle Aged; D010328:Patch Tests; D010476:Perfume / Q000009:adverse effects; D011310:Preservatives, Pharmaceutical / Q000009:adverse effects; D015995:Prevalence; D012189:Retrospective Studies; D013785:Thailand / Q000453:epidemiology; D055815:Young Adult
chemical_list: D000485:Allergens; D003358:Cosmetics; D010476:Perfume; D011310:Preservatives, Pharmaceutical; D008627:Mercuric Chloride; D000641:Ammonia; C028431:mercuric chloride, ammoniated