Proportion of Lifetime UV Dose Received by Children, Teenagers and Adults Based on Time-Stamped Personal Dosimetry
2004; Elsevier BV; Volume: 123; Issue: 6 Linguagem: Inglês
10.1111/j.0022-202x.2004.23466.x
ISSN1523-1747
AutoresElisabeth Thieden, Peter A. Philipsen, Jane Sandby‐Møller, Jakob Heydenreich, Hans Christian Wulf,
Tópico(s)bioluminescence and chemiluminescence research
ResumoUltraviolet (UV) reduction campaigns since 1986 were based on the estimation that individuals get 80% of their cumulative lifetime UV dose by the age of 18. To investigate if this estimation is true, we compared annual UV doses received during life in 164 Danish volunteers: children, teenagers, indoor workers, and golfers (age range 4–67 y) who recorded sun exposure behavior in diaries and carried personal UV dosimeters, measuring time-stamped UV doses. The annual UV dose did not significantly correlate with age but the variation in annual UV dose was high (median 166 SED (standard erythema dose), 95% range: 37–551 SED). The annual UV dose did correlate with days with risk behavior (sunbathing/exposing upper body) (r=0.51, p<0.001) and in adults also with hours performing outdoor sports (r=0.39, p<0.001), gardening, and sun-bed sessions (r=0.26, p=0.02). Teenagers had significantly more days with risk behavior than adults (21 vs 13 d, p=0.006) but not than children (15 d). No differences in UV dose among the age groups were found on workdays. Only 25% of the lifetime UV dose was received before the age of 20 and the annual UV dose was thus independent of age. Reduction of cumulative lifetime UV dose could be obtained by minimizing risk behavior. Ultraviolet (UV) reduction campaigns since 1986 were based on the estimation that individuals get 80% of their cumulative lifetime UV dose by the age of 18. To investigate if this estimation is true, we compared annual UV doses received during life in 164 Danish volunteers: children, teenagers, indoor workers, and golfers (age range 4–67 y) who recorded sun exposure behavior in diaries and carried personal UV dosimeters, measuring time-stamped UV doses. The annual UV dose did not significantly correlate with age but the variation in annual UV dose was high (median 166 SED (standard erythema dose), 95% range: 37–551 SED). The annual UV dose did correlate with days with risk behavior (sunbathing/exposing upper body) (r=0.51, p<0.001) and in adults also with hours performing outdoor sports (r=0.39, p 3.0.CO;2-RCrossref PubMed Scopus (0) Google Scholar;Armstrong and Kricker, 2001Armstrong B.K. Kricker A. The epidemiology of UV induced skin cancer.J Photochem Photobiol B. 2001; 63: 8-18https://doi.org/10.1016/S1011-1344(01)00198-1Crossref PubMed Scopus (1235) Google Scholar;Phalberg et al., 2001Phalberg A. Kolmel K.F. Gefeller O. Febim Study Group Timing of excessive ultraviolet radiation and melanoma: Epidemiology does not support the existence of a critical period of high susceptibility to solar ultraviolet radiation- induced melanoma.Br J Dermatol. 2001; 144: 471-475https://doi.org/10.1046/j.1365-2133.2001.04070.xCrossref PubMed Scopus (97) Google Scholar;Whiteman et al., 2001Whiteman D.C. Whiteman C.A. Green A.C. Childhood sun exposure as a risk factor for melanoma: A systematic review of epidemiologic studies.Cancer Causes Control. 2001; 12: 69-82https://doi.org/10.1023/A:1008980919928Crossref PubMed Scopus (480) Google Scholar). With an expected life span of 80 y, people would get about 25% of the lifetime UV dose before the age of 20 if the annual sun exposure were independent of age. Most research and public UV reduction campaigns, however, were based on the estimation that the average child receives three times the annual UV dose of the average adult (Stern et al., 1986Stern R.S. Weinstein M.C. Baker S.G. Risk reduction for nonmelanoma skin cancer with childhood sunscreen use.Arch Dermatol. 1986; 122: 537-545https://doi.org/10.1001/archderm.122.5.537Crossref PubMed Google Scholar). This has been cited 184 times in peer-reviewed journals and in public UV campaigns, i.e., by the World Health Organization (WHO), it resulted in the assumption that individuals get 80% of their lifetime UV dose during the first 18 y of life. Subsequently, this assumption has been spread worldwide through Internet sites as the scientific truth (i.e., http://www.who.int./phe/uv). 1http://www.who.int/phe/uv; http://www.skincancer.org; http://www.epa.gov/sunwise/kids.html; http://www.cdc.gov/cancer/nscpep/skin.htm; http://www.cancer.gov/newscenter/individualmelanoma1http://www.who.int/phe/uv; http://www.skincancer.org; http://www.epa.gov/sunwise/kids.html; http://www.cdc.gov/cancer/nscpep/skin.htm; http://www.cancer.gov/newscenter/individualmelanoma Dosimeter studies of UV exposure have been done worldwide but none have compared children and adults over month during daily life and vacation that could clarify if the age ratio of lifetime UV exposure was true (Slaper, 1987Slaper H. Skin cancer and UV exposure: investigations on the estimation of risks. University of Utrecht, The Netherlands1987: 24-48Google Scholar;Diffey et al., 1996Diffey B.L. Gibson C.J. Haylock R. McKinlay A.F. Outdoor ultraviolet exposure of children and adolescents.Br J Dermatol. 1996; 134: 1030-1034https://doi.org/10.1046/j.1365-2133.1996.d01-896.xCrossref PubMed Google Scholar;Gies et al., 1998Gies P. Roy C. Toomey S. MacLennan R. Watson M. Solar UVR exposure of primary school children at three locations in Queensland.Photochem Photobiol. 1998; 68: 78-83https://doi.org/10.1562/0031-8655(1998)068<0078:SUEOPS>2.3.CO;2Crossref PubMed Google Scholar;Kimlin et al., 1998Kimlin M.G. Parisi A.V. Wong J.C.F. Quantification of personal solar UV exposure of outdoor workers, indoor workers and adolescents at two locations in Southeast Queensland.Photodermatol Photoimunol Photomed. 1998; 14: 7-11Crossref PubMed Scopus (74) Google Scholar;Moise et al., 1999Moise A.F. Harrison S.L. Gies H.P. Solar ultraviolet radiation exposure of infants and small children.Photodermatol Photoimunol Photomed. 1999; 15: 109-114Crossref PubMed Scopus (18) Google Scholar;Parisi et al., 2000Parisi A.V. Meldrum L.R. Wong J.C.F. Aitken J. Fleming R.A. Effect of childhood and adolescent ultraviolet exposures on cumulative exposure in South East Queensland schools.Photodermatol Photoimunol Photomed. 2000; 16: 19-24https://doi.org/10.1034/j.1600-0781.2000.160106.xCrossref PubMed Scopus (26) Google Scholar;Guy et al., 2003Guy C. Diab R. Martincigh B. Ultraviolet radiation exposure of children and adolescents in Durban, South Africa.Photochem Photobiol. 2003; 77: 265-270https://doi.org/10.1562/0031-8655(2003)077<0265:UREOCA>2.0.CO;2Crossref PubMed Google Scholar). Based on daily outdoor activity profiles in US and ambient UV measurements,Godar, 2001Godar D.E. UV doses of American children and adolescents.Photochem Photobiol. 2001; 74: 787-793https://doi.org/10.1562/0031-8655(2001)074<0787:UDOACA>2.0.CO;2Crossref PubMed Scopus (0) Google Scholar andGodar et al., 2001Godar D.E. Wengraitis S.P. Shreffler J. Sliney D.H. UV doses of Americans.Photochem Photobiol. 2001; 73: 621-629https://doi.org/10.1562/0031-8655(2001)073<0621:UDOA>2.0.CO;2Crossref PubMed Scopus (0) Google Scholar,Godar et al., 2003Godar D.E. Urbach F. Gasparro F.P. van der Leun J.C. UV doses of young adults.Photochem Photobiol. 2003; 77: 453-457https://doi.org/10.1562/0031-8655(2003)077<0453:UDOYA>2.0.CO;2Crossref PubMed Scopus (0) Google Scholar recently estimated the annual UV dose to be very stable during life. With the purpose to determine the percentage of lifetime UV doses received in childhood and adolescence we performed a prospective study in all ages by objective personal, electronic, time-stamped dosimetry and sun exposure diaries (Thieden et al, 2004). Table I shows the monthly distribution of ambient UV doses and the percentage received of ambient UV doses in Denmark by the subjects. By far, the highest percentage of ambient UV doses was received on days off work in July and on sun holidays. There was no significant correlation between age and annual UV dose except among subjects below 20 y (r=0.23, p=0.04). Figure 1 shows that the variation in UV doses between individuals was very high and age independent. Table II shows the annual UV dose and percentage of the cumulative lifetime UV dose during childhood, teen years, and adulthood. The median annual UV dose received during life was relatively constant, only in the teen years a 14%–24% higher annual UV dose was received than in the years before and after, but significantly higher only than in childhood (p=0.03). The percentage of lifetime UV dose received before the age of 20 was 25% as expected, if the annual UV dose was constant through life. We found no differences in annual UV dose between males and females in adults but a significant higher UV exposure in females than in males below 20 y (p=0.008).Table IAmbient UV doses in Copenhagen, Denmark 1999 (average of all days); UV dose received per day to the wrist expressed as a percentage of the corresponding ambient UV doseAmbient UV dose in SEDUV dose received per day in % of ambient UV dose in DK Median (95% range)Total monthlyMedian per dayMax per dayWorkdaysaIn children and teenagers, workdays are equal to school days. in DenmarkDays off work in DenmarkSun holidays in Southern EuropebSouthern Europe=Mediterranean area.June74627381.7 (0–13.8)2.1 (0–27.8)5.4 (0–135)July75124391.7 (0–19.8)4.5 (0–44.2)21.1 (0–191)August46414250.9 (0–13.0)1.7 (0–39.9)22.2 (0.3–186)September32511190.7 (0–14.8)0.9 (0–29.0)5.1 (0–190)October1114.15.90 (0–5.8)0 (0–11.6)0.7 (0–169)Average of 15,478 participation days in Denmark with UV dosimeter measurements). On sun holidays in Southern Europe (673 d) the UV doses were expressed as a percentage of the ambient UV dose in Copenhagen on corresponding days.UV, ultraviolet; SED, standard erythema dose; DK, Denmark.a In children and teenagers, workdays are equal to school days.b Southern Europe=Mediterranean area. Open table in a new tab Table IIAnnual UV dose in SED, cumulative UV dose and the percentage of measured lifetime UV dose compared to the age expected during different age intervals if annual UV dose is constantGroupSubjects NAge intervals (years)Annual UV dose in SED Median (95% range)Cumulative UV dose in age intervals in SED% of lifetime UV doseMeasuredExpectedChildren45≥1 and <13149 (23–523)178814.515.8Teenagers35≥13 and <20185aSignificantly higher than children below 13 y old (p=0.032). (71–634)129510.59.2Adults84≥20 and <77162 (36–663)923475.075.0Total164≥1 and <77166 (37–551)12,317100100These percentages assuming that no UV radiation exposure occurs before the age of 1, that people live up to the age of 77 (Statistics Denmark, Demographic data: http://www.dst.dk), that annual UV dose from 2 to 4 y of age=annual UV dose from 4 to 12 y of age and annual UV dose from 68 to 77 y of age=UV dose from 20 to 67 y of age, since we only have measurements from 4 to 67 years of age (Thieden et al., 2004aThieden E. Philipsen P.A. Heydenreich J. Wulf H.C. UV radiation exposure related to age, sex, occupation, and sun behavior based on time-stamped personal dosimeter readings.Arch Dermatol. 2004; 140: 197-203https://doi.org/10.1001/archderm.140.2.197Crossref PubMed Scopus (157) Google Scholar).UV, ultraviolet; SED, standard erythema dose.a Significantly higher than children below 13 y old (p=0.032). Open table in a new tab Average of 15,478 participation days in Denmark with UV dosimeter measurements). On sun holidays in Southern Europe (673 d) the UV doses were expressed as a percentage of the ambient UV dose in Copenhagen on corresponding days. UV, ultraviolet; SED, standard erythema dose; DK, Denmark. These percentages assuming that no UV radiation exposure occurs before the age of 1, that people live up to the age of 77 (Statistics Denmark, Demographic data: http://www.dst.dk), that annual UV dose from 2 to 4 y of age=annual UV dose from 4 to 12 y of age and annual UV dose from 68 to 77 y of age=UV dose from 20 to 67 y of age, since we only have measurements from 4 to 67 years of age (Thieden et al., 2004aThieden E. Philipsen P.A. Heydenreich J. Wulf H.C. UV radiation exposure related to age, sex, occupation, and sun behavior based on time-stamped personal dosimeter readings.Arch Dermatol. 2004; 140: 197-203https://doi.org/10.1001/archderm.140.2.197Crossref PubMed Scopus (157) Google Scholar). UV, ultraviolet; SED, standard erythema dose. Parameters considered when analyzing the annual UV dose were: (A) Number of days with risk behavior especially in sunny countries. (B) Sun-bed sessions, hours with gardening or outdoor sports. (C) UV doses received during workdays. (A) Risk behavior: We found a significant correlation between annual UV dose and number of risk behavior days (r=0.51, p<0.001). Teenagers had significantly more risk behavior days (21 d, 95% range: 3–45 d) than adults (13 d, 95% range: 0–45 d) (p<0.006), but not significantly more than children below 13 y (15 d, 95% range: 1–52 d). There were no significant differences between the groups in number of days on sun holidays in Southern Europe. During the measurement period 55% (95% range: 0%–96%) of the UV dose was received on risk behavior days. Teenagers received even 76% (95% range: 4%–98%) on risk behavior days significantly more than children (p=0.017) and adults (p<0.001). (B) Sun-bed sessions, hours gardening or with outdoor sport: In adults, we found a significant correlation between annual UV *dose and sun-bed sessions, number of hours gardening (r=0.26, p=0.02) or with outdoor sports (r=0.39, p 2.0.CO;2Crossref PubMed Scopus (0) Google Scholar,Godar et al., 2003Godar D.E. Urbach F. Gasparro F.P. van der Leun J.C. UV doses of young adults.Photochem Photobiol. 2003; 77: 453-457https://doi.org/10.1562/0031-8655(2003)077<0453:UDOYA>2.0.CO;2Crossref PubMed Scopus (0) Google Scholar). We proved by objective, personal, time-stamped dosimeter readings of erythemally weighted UV doses that individuals get 25% of their cumulative lifetime UV dose before the age of 20, and that individuals get about the same annual UV dose regardless of their age. If young people today get a lower annual UV dose than earlier due to the increasing computer and Internet culture cannot be revealed since previous measurements are not available (Godar et al., 2003Godar D.E. Urbach F. Gasparro F.P. van der Leun J.C. UV doses of young adults.Photochem Photobiol. 2003; 77: 453-457https://doi.org/10.1562/0031-8655(2003)077<0453:UDOYA>2.0.CO;2Crossref PubMed Scopus (0) Google Scholar). Besides, UV doses obtained on workdays are very small and major difference between the age groups are needed to change the cumulative lifetime UV age ratio. As our results are based ononly 164 participants, the ratio between children, teenagers, and adults is depending on the chosen adult group. Our adult group consisted of 74% hospital employees, who get a lower UV dose than the average adult and 26% golfers who get a higher (Thieden et al., 2004aThieden E. Philipsen P.A. Heydenreich J. Wulf H.C. UV radiation exposure related to age, sex, occupation, and sun behavior based on time-stamped personal dosimeter readings.Arch Dermatol. 2004; 140: 197-203https://doi.org/10.1001/archderm.140.2.197Crossref PubMed Scopus (157) Google Scholar). If we had chosen the hospital employees only, the percentage of lifetime UV dose obtained before the age of 20 will increase from 25% to 27.6%, which must be considered the highest possible. Even then only teenagers but not children receive a significantly higher annual UV dose than adults. The US cumulative lifetime UV study did not include indoor tanning or vacation UV doses. But vacation UV doses were given as weighted average estimates, which were assumed to increase the annual UV dose for an American with 30% but not to change the percentage of the individual's lifetime UV dose (Godar et al., 2003Godar D.E. Urbach F. Gasparro F.P. van der Leun J.C. UV doses of young adults.Photochem Photobiol. 2003; 77: 453-457https://doi.org/10.1562/0031-8655(2003)077<0453:UDOYA>2.0.CO;2Crossref PubMed Scopus (0) Google Scholar). In Denmark, the ambient UV doses are only beyond the erythema threshold from April to September, thus differences between age groups can only be revealed if sun exposure during vacation was included since high UV doses mostly are received during vacations and weekends in the summer period. About one third of the annual UV dose was received in July when all children and teenagers and most adults had vacation and the UV dose was thus independent of age. A dosimeter study during a summer period but not including school holidays in UK showed higher UV doses among 9–10-y-olds than 14–15-y-olds (Diffey et al., 1996Diffey B.L. Gibson C.J. Haylock R. McKinlay A.F. Outdoor ultraviolet exposure of children and adolescents.Br J Dermatol. 1996; 134: 1030-1034https://doi.org/10.1046/j.1365-2133.1996.d01-896.xCrossref PubMed Google Scholar). If we constrict our data to school days in these age intervals we find a significant higher daily UV dose in children too (p=0.007), indicating that it is the UV doses received during school holidays that make the distinction in the annual UV dose between children and teenagers. Our data show that the variation in UV dose between individuals are very great and that outdoor activities, not age, discriminate between high and low UV dose, as also reported in other studies (Diffey et al., 1996Diffey B.L. Gibson C.J. Haylock R. McKinlay A.F. Outdoor ultraviolet exposure of children and adolescents.Br J Dermatol. 1996; 134: 1030-1034https://doi.org/10.1046/j.1365-2133.1996.d01-896.xCrossref PubMed Google Scholar;Thieden et al., 2001Thieden E. Ågren M.S. Wulf H.C. Solar UVR exposures of indoor workers in a Working and a Holiday Period assessed by personal dosimeters and sun exposure diaries.Photodermatol Photoimmunol Photomed. 2001; 17: 249-255https://doi.org/10.1034/j.1600-0781.2001.170601.xCrossref PubMed Scopus (48) Google Scholar,Thieden et al., 2004aThieden E. Philipsen P.A. Heydenreich J. Wulf H.C. UV radiation exposure related to age, sex, occupation, and sun behavior based on time-stamped personal dosimeter readings.Arch Dermatol. 2004; 140: 197-203https://doi.org/10.1001/archderm.140.2.197Crossref PubMed Scopus (157) Google Scholar). The differences in annual UV doses are more than anything else dependent on number of days with risk behavior. All children and teenagers and 94% of the adults had days with risk behavior. The increased percentage of lifetime UV dose in the teen years is highly connected to more days with risk behavior (Thieden et al., 2004aThieden E. Philipsen P.A. Heydenreich J. Wulf H.C. UV radiation exposure related to age, sex, occupation, and sun behavior based on time-stamped personal dosimeter readings.Arch Dermatol. 2004; 140: 197-203https://doi.org/10.1001/archderm.140.2.197Crossref PubMed Scopus (157) Google Scholar). As sun bed use was not significantly higher among teenagers than adults, this could not be the explanation. Gardening and golfing mainly performed by adults add significantly to the annual UV dose too, while shorter-lasting outdoor sports as ball plays and biking did not. This supports the findings that patients with basal cell carcinoma significantly more often are golfers than matched controls (p=0.04) (Lock-Andersen and Wulf, 1997Lock-Andersen J. Wulf H.C. Non-melanoma skin cancer: The Danish case–control study.Australas J Dermatol. 1997; 38 (Abstract 2315): 161PubMed Google Scholar). In contrast to the US study, where females were estimated to get the lowest annual UV dose we found no differences in annual UV dose between men and women, but girls below 20 y got higher annual UV dose than boys (Godar et al., 2003Godar D.E. Urbach F. Gasparro F.P. van der Leun J.C. UV doses of young adults.Photochem Photobiol. 2003; 77: 453-457https://doi.org/10.1562/0031-8655(2003)077<0453:UDOYA>2.0.CO;2Crossref PubMed Scopus (0) Google Scholar). Besides females in all age groups, spent more days with risk behavior including sun-bed sessions (p<0.001) and thus received their UV in peaks with a great part of the body exposed while males had a more even exposure pattern (Danish National Board of Health, 2000Danish National Board of Health Telephonic Investigation of the Sun Habits of the Danes. ISBN 87-90951-33-6. 2000Google Scholar;Thieden et al., 2004aThieden E. Philipsen P.A. Heydenreich J. Wulf H.C. UV radiation exposure related to age, sex, occupation, and sun behavior based on time-stamped personal dosimeter readings.Arch Dermatol. 2004; 140: 197-203https://doi.org/10.1001/archderm.140.2.197Crossref PubMed Scopus (157) Google Scholar). That might contribute to the explanation why women have a higher incidence of melanoma (Danish National Board of Health, 1998Danish National Board of Health 1998http://www.sst.dk/publ/pub/1999/solvanerGoogle Scholar). Although individuals before the age of 20 do not get a higher percentage of lifetime UV dose than expected, especially teenagers had many UV peak days receiving up to the double daily SED than adults. Reduction of the cumulative lifetime UV dose among Danes and other populations in geographic areas without year-round high-intensity sunlight, is most effectively obtained by throughout life reducing the UV dose received in the 1–2 wk yearly with risk behavior. One hundred and sixty-four volunteers (69 male and 95 females) from the Copenhagen area took part in the study (median 112 d, range 32–137 d). The subjects, all with Scandinavian ancestors and without a history of skin disorders, comprised: 45 children from kindergarten and primary school (range 4–12 y), 35 teenagers from secondary and high school (range 13–19 y), 62 indoor workers from our hospital and 22 golfers from one golf club (range 21–67 y). There were no significant differences in skin type among the age groups (I: 9%, II: 27%, III: 46%, IV: 18%) or in sunscreen use between children and teenagers but teenagers applied sunscreen on more days than adults (p<0.02) and had more sunburn days than both children and adults (p<0.01). The study was performed over a period of five summer months in Denmark, latitude 56°N. The participants gave their written informed consent. The Scientific Ethical Committees for Copenhagen and Frederiksberg approved the study (KF11-007/99), which was conducted according to Declaration of Helsinki Principles. Solar UV radiation was measured with an UV-Biometer model 501 (Solar Light, Philadelphia, Pennsylvania) on the roof of a 7-floor building at our hospital. The spectral response was similar to the CIE (International Commission on Illumination) erythema action spectrum (McKinlay and Diffey, 1987McKinlay A.F. Diffey B.L. A reference action spectrum for ultraviolet induced erythema in human skin.CIE J. 1987; 6: 17-22Google Scholar). The measurements are expressed in SED, where 1 SED=100 J per m2 normalized to 298 nm (Wulf et al., 1996Wulf H.C. Lock-Andersen J. The Scandinavian Photodermatology Reseach Group Standard erythema dose.Skin Res Technol. 1996; 4: 192Google Scholar;Diffey et al., 1997Diffey B.L. Jansén C.T. Urbach F. Wulf H.C. Standard erythema dose. A review.CIE (International Commission on Illumination). 1997; 125: 1-5Google Scholar). The dosimeter comprises a sensor and a data logger. It is mounted in a housing together with a digital watch and serves as a wrist watch (Thieden et al., 2000Thieden E. Ågren M.S. Wulf H.C. The wrist is a reliable body site for personal dosimetry of ultraviolet radiation.Photodermatol Photoimmunol Photomed. 2000; 16: 57-61https://doi.org/10.1034/j.1600-0781.2000.d01-4.xCrossref PubMed Scopus (83) Google Scholar). A Silicon Carbide Photodiode (JECF1-IDE; Laser Components, Olching, Germany), was chosen as sensor only sensitive in the range 200–400 nm. The sensor has a built in diffuser and has cosine response. The spectral response is similar to the CIE erythema action spectrum (McKinlay and Diffey, 1987McKinlay A.F. Diffey B.L. A reference action spectrum for ultraviolet induced erythema in human skin.CIE J. 1987; 6: 17-22Google Scholar). The data logger controls the sensor which was set to measure every eighth second and to store the average of the last 75 measurements every 10 min together with the time. Measurement range of the dosimeter is 0.1 SED per h to 23 SED per h. The UV dosimeter is battery driven and can run for 145 d without maintenance and data can be transferred to a personal computer. The subjects were instructed to replace their normal wristwatch with the UV dosimeter and wear it continuously at least between 07:00 and 19:00 h, during sun-bed use, and to place it on a towel with the sensor upwards during swimming (Thieden et al., 2004aThieden E. Philipsen P.A. Heydenreich J. Wulf H.C. UV radiation exposure related to age, sex, occupation, and sun behavior based on time-stamped personal dosimeter readings.Arch Dermatol. 2004; 140: 197-203https://doi.org/10.1001/archderm.140.2.197Crossref PubMed Scopus (157) Google Scholar, Thieden et al., 2004bThieden E. Philipsen P.A. Sandby-Møller J. Wulf H.C. Sunburn related to UV radiation exposure, age, sex, occupation, and sun-bed use based on time- stamped personal dosimeter readings.Arch Dermatol. 2004Google Scholar). The participants (or the parents of 18 children <10 y) were provided with a sun exposure diary where they daily crossed "Yes" or "No" to the following questions: (1) Did you wear the SunSaver today? (2) Are you off work/school or on holiday today? (3) Are you abroad today? If yes write country code. (4) Did you sunbathe today? (Sitting or lying in the sun (or sun bed)) with upper body or shoulders exposed to get a tan. (5) Have you exposed your shoulders or upper body outdoors today? (6) Have you been at the beach or at the Sea today? In the following we considered "Yes" to question 4 or 5, as "risk behavior", since a great part of the body is sun exposed. Hours spent gardening and with outdoor sports were reported in a questionnaire. The analyses of the monthly distribution of UV radiation doses were based on 16,668 d hereof 5607 d among children and 2331 d among teenagers with both UV dosimeter measurements and diary information. In all other calculations, each of the 164 subjects weighted equally independent of number of participation days. To make the individual doses comparable, the annual UV dose for each subject was calculated on the basis of UV doses actually received to the wrist in median 112 d in the summer-half-year and estimated percentage of ambient UV measurements in the rest of the year, the exact calculations is described earlier (Thieden et al, 2004). We used non-parametric statistics since most of the data were not normally distributed. The results are therefore given as median (95% range). Mann–Whitney U-test was used to compare unpaired continuous data between groups and Spearman's rank correlation was used to investigate interactions between two continuous measurements. In each case a p-value of less than 0.05 was considered significant. We used SPSS for Windows, version 11.5 (SPSS, Chicago, Illinois) for data analysis. This study was funded by the European Community Environment and Climate 1994–1998 Work Programme Contract no. ENV4-CT97-0556. We thank the participants and contact persons, the staff of the Department of Dermatology D92 especially Trine Ravn Brinck for help with data collection and RemRem Gentofte, Denmark, for providing wrist watchstraps.
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