title: Different responses of the melanin index to ultraviolet irradiation in relation to skin color and body site.
abstract: OBJECTIVE
  Few reports describe UVB irradiation-induced pigmentation responses from different skin colors or from different body sites. This study determined pigmentation changes in skin with different colors and from different body sites following 308-nm excimer laser irradiation.
  
  
  METHODS
  Ten healthy Korean adults were divided into light- and dark-skin groups, and irradiated body sites were divided into unexposed zones (UZ), intermittently exposed zones (IEZ), and frequently exposed zones (FEZ). Twenty-four areas were irradiated with a single 300-mJ/cm(2) shot delivered by an excimer laser. MIs were measured before irradiation, immediately after irradiation, and then 1 day, 3 days, 7 days, 14 days, and 21 days after irradiation.
  
  
  RESULTS
  MIs declined significantly on day 1 after irradiation, particularly in light-colored skin. In the light-skin group, the MI increased from day 3 after irradiation and continued to increase for 21 days, whereas in the dark-skin group, the peak MI was reached at 7 days and declined thereafter. The peak MIs were reached at 7 days in the IEZ and FEZ and at 14 days in the UZ.
  
  
  CONCLUSIONS
  Following UVB irradiation, MIs decreased, particularly in light-colored skin, before delayed tanning developed. UVB-induced pigmentation varied according to different skin colors and the body sites irradiated.
authors.affiliation: Department of Dermatology, Seoul National University Bundang Hospital, Seongnam, Korea.
authors.forename: Jung Won
authors.initials: JW
authors.lastname: Shin
authors.forename: Sung Whan
authors.initials: SW
authors.lastname: Yoon
authors.forename: Jeong Bok
authors.initials: JB
authors.lastname: Jeong
authors.forename: Kyung Chan
authors.initials: KC
authors.lastname: Park
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D008543:Melanins / Q000378:metabolism*; D056910:Republic of Korea; D012880:Skin Pigmentation; D014466:Ultraviolet Rays
chemical_list: D008543:Melanins
keywords: UVB; excimer laser; melanin index; pigmentation; skin color