title: Sunlight exposure-mediated DNA damage in young adults.
abstract: BACKGROUND
  Previous experimental studies showed that single ultraviolet B (UVB) light irradiation increased levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG), a well-established biomarker of carcinogenesis and oxidative DNA damage, in epithelial cells in animals and humans. We conducted for the first time an epidemiologic study to investigate the correlations among levels of oxidative DNA damage, skin pigmentation, and sunlight exposure in human daily life.
  
  
  METHODS
  Digitalized skin pigmentation levels and creatinine-adjusted urinary 8-OHdG levels were examined in 127 healthy young adults aged 20 to 24 years and in hairless mice with normal pigmented skin (HL-mice; n = 20) and hyperpigmented skin (HL-HPS-mice; n = 20). Data obtained by a questionnaire were also analyzed for the 127 subjects.
  
  
  RESULTS
  Binary logistic regression analysis showed that increased sunlight intensity, but not sunlight-exposed time or sunlight-exposed skin area, was correlated with elevation in creatinine-adjusted urinary 8-OHdG levels. In contrast, increased skin pigmentation level, but not the use of sunscreen, was correlated with reduction in urinary 8-OHdG level in humans. UVB irradiation corresponding to several minutes of sunlight exposure significantly increased urinary 8-OHdG levels in HL-mice but not in HL-HPS-mice.
  
  
  CONCLUSIONS
  We showed that increase in intensity of sunlight in human daily life increased levels of DNA damage. We also showed a protective effect of skin pigmentation on sunlight exposure-mediated DNA damage.
  
  
  CONCLUSIONS
  We have provided more reliable evidence of routine sunlight exposure-mediated DNA damage in humans through the combination of epidemiologic and experimental studies.
authors.affiliation: Department of Biomedical Sciences, College of Life and Health Sciences, Chubu University, Kasugai-shi, Aichi, Japan. katomasa@isc.chubu.ac.jp
authors.forename: Masashi
authors.initials: M
authors.lastname: Kato
authors.forename: Machiko
authors.initials: M
authors.lastname: Iida
authors.forename: Yuji
authors.initials: Y
authors.lastname: Goto
authors.forename: Takaaki
authors.initials: T
authors.lastname: Kondo
authors.forename: Ichiro
authors.initials: I
authors.lastname: Yajima
mesh_terms: D000328:Adult; D000818:Animals; D004249:DNA Damage; D004195:Disease Models, Animal; D005260:Female; D006801:Humans; D008297:Male; D051379:Mice; D008812:Mice, Hairless; D008810:Mice, Inbred C57BL; D012867:Skin / Q000528:radiation effects*; D013472:Sunlight / Q000009:adverse effects*; D055815:Young Adult