title: Sunlight-induced DNA damage in human mononuclear cells.
abstract: In this study of 301 blood samples from 21 subjects, we found markedly higher levels of DNA damage (nonpyrimidine dimer types) in the summer than in the winter detected by single-cell gel electrophoresis. The level of DNA damage was influenced by the average daily influx of sunlight < 50 days prior to blood sampling. The 3 and 6 day periods before sampling influenced DNA damage the most. The importance of sunlight was further emphasized by a positive association of the DNA damage level to the amount of time the subjects had spent in the sun over a 3 day period prior to the sampling. The effect of sunlight was comparable to the interindividual variation, indicating that sunlight exposure and the individual's background were the two most important determinants for the basal level of DNA damage. Influence of other lifestyle factors such as exercise, intake of foods, infections, and age could not be detected. Our results suggest that sunlight penetrates the outer layer of the human epidermis and damages the DNA in mononuclear cells circulating in the vessels of the skin.
authors.affiliation: National Institute of Occupational Health, Lersø Parkallé 105, DK-2100 Copenhagen Ø, Denmark. fipm@farmakol.ku.dk
authors.forename: Peter
authors.initials: P
authors.lastname: Moller
authors.forename: Hakan
authors.initials: H
authors.lastname: Wallin
authors.forename: Erik
authors.initials: E
authors.lastname: Holst
authors.forename: Lisbeth E
authors.initials: LE
authors.lastname: Knudsen
mesh_terms: D000328:Adult; D002467:Cell Nucleus / Q000648:ultrastructure; D004247:DNA / Q000032:analysis; D004249:DNA Damage; D004781:Environmental Exposure; D005260:Female; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000648:ultrastructure*; D008019:Life Style; D016014:Linear Models; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012621:Seasons; D012737:Sex Factors; D013472:Sunlight / Q000009:adverse effects*; D013997:Time Factors
chemical_list: D004247:DNA