Urinary thymidine dimer excretion reflects personal ultraviolet radiation exposure levels.

Exposure to ultraviolet radiation (UVR) leads to skin DNA damage, specifically in the form of cyclobutane pyrimidine dimers, with thymidine dimers being the most common. Quantifying these dimers can indicate the extent of DNA damage resulting from UVR exposure. Here, a new liquid chromatography-mass spectrometry (LC-MS) method was used to quantify thymidine dimers in the urine after a temporary increase in real-life UVR exposure. Healthy Danish volunteers (n = 27) experienced increased UVR exposure during a winter vacation. Individual exposure, assessed via personally worn electronic UVR dosimeters, revealed a mean exposure level of 32.9 standard erythema doses (SEDs) during the last week of vacation. Morning urine thymidine dimer concentrations were markedly elevated both 1 and 2 days post-vacation, and individual thymidine dimer levels correlated with UVR exposure during the last week of the vacation. The strongest correlation with erythema-weighted personal UVR exposure (Power model, r2 = 0.64, p < 0.001) was observed when both morning urine samples were combined to measure 48-h thymidine dimer excretion, whereas 24-h excretion based on a single sample provided a weaker correlation (Power model, r2 = 0.55, p < 0.001). Sex, age, and skin phototype had no significant effect on these correlations. For the first time, urinary thymidine dimer excretion was quantified by LC-MS to evaluate the effect of a temporary increase in personal UVR exposure in a real-life setting. The high sensitivity to elevated UVR exposure and correlation between urinary excretion and measured SED suggest that this approach may be used to quantify DNA damage and repair and to evaluate photoprevention strategies.

"No alcohol, no party": an explorative study of young Danish moderate drinkers.

BACKGROUND: Danish youth has for years had the highest alcohol consumption in Europe, however recent surveys show that consumption levels have diminished slightly and that the age of first intoxication has been raised. AIM: To explore young moderate drinkers' attitudes, values, and behaviour in relation to alcohol consumption. DESIGN, SETTING, AND PARTICIPANTS: Data consists of 10 individual semi-structured interviews with 16-17-year-old moderate drinkers attending high school in Copenhagen, Denmark. RESULTS: The study shows that the respondents perceive drinking as a necessity for feeling included at parties, but also that they do not feel a need to drink large amounts of alcohol in order to feel this social inclusion. The study finds that respondents employ a number of different behavioural and cognitive strategies aimed at controlling their own and close friends' drinking behaviour, and that short-term negative social implications are of much greater concern than long-term health consequences. In addition, the study shows that parents have a limited direct influence in this group. CONCLUSIONS: The study identifies a group of young people who have clearly defined restrictions as to what they consider positive drinking behaviour. As parents and long-term health consequences only have an limited influence on the respondents' drinking behaviour, these elements should not have primary focus in future interventions. In stead, interventions should take into account the social dynamics involved in drinking and recognise that the social qualities surrounding alcohol weighs higher among this group of young people than the quantity of alcohol consumed.