Personal Ultraviolet Radiation Research Articles

Ultraviolet radiation thin film dosimetry: A review of properties and applications.

Spectroradiometry, radiometry, and dosimetry are employed for the measurement of ultraviolet radiation (UVR) irradiance and non-ionizing exposure. Different types of UVR dosimeter have been developed for measuring personal and environmental UVR exposures since film dosimetry was pioneered in the 1970s. An important type of dosimeter is the thin film variant, which contains materials that undergo changes in optical absorbance when exposed to UVR. These changes can be measured at a specific wavelength using a spectrophotometer. Thin film dosimeters allow UVR exposure measurements on humans at various body sites during daily activities, as well as on plants, animals, and any sites of interest when utilized in a field environment. This review examines the properties and applications of five types of thin film UVR dosimeter that have different dynamic exposure limits and spectral responses. Polysulphone, with a spectral response approximating the human erythema action spectrum, was one of the first materials employed in thin film form for the measurement of UVR exposures up to 1 day, and up to 6 days with an extended dynamic range filter. Polyphenylene oxide has been characterized and employed for personal UVR exposure measurements up to approximately four summer days and has also been used for long-term underwater UVR exposures. Phenothiazine and 8-methoxypsoralen have been reported as suitable for the measurement of longer wavelength UVA exposures. Finally, polyvinyl chloride with an extended dynamic exposure range of over 3 weeks has been shown to have predominantly a spectral response in the UVB and extending up to 340 nm.

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.Graphical abstract

Smart City and the digital measurement of solar ultraviolet radiation in Outdoor workers in the City of Lisbon

Abstract The growing incidence of skin cancer over the years has made it a significant public health problem. However, technology can be used to tackle the skin cancer which is highly preventable, mainly through reduced exposure to solar ultraviolet radiation (UVR). Digital services can be used to promote individual and collective protective measures and interventions. Specifically, there is an opportunity when the exposure is intermittent or continuous, and occurs in an occupational or leisure setting. We are using a digital platform to contribute to raising public and policy awareness on solar UVR-inflicted occupational skin cancers in the municipality of Lisbon. The digital platform is performing direct measurements of the solar UVR dose received by outdoor workers. Results will likely contribute to further understanding the risk estimates for keratinocyte cancer estimations in this population. The digital platform integrates a personal electronic dosimeter (GENESIS-UV system) to assess occupational solar UVR doses of gardeners, masons, and gravediggers of the municipality of Lisbon. Two hundred and ten outdoor workers were selected to wear the dosimeter for 1 month each, between April and October during their daily working hours. The digital platform that offers private access to information through dashboard visualization provided information for the outdoor workers and facilitate communication with the participants. Study data provides the outdoor workers with information on their personal solar UVR exposure during their working hours and an estimate of their risk of developing skin cancer. The results prospectively should flow into the design of adequate prevention campaigns for skin cancer in outdoor workers.

Ultraviolet sun exposure and sun protection behaviors in outdoor rock climbers

BackgroundOverexposure to sunlight and sunburn are the main preventable causes of skin cancer. Outdoor sports are associated with significant levels of sunlight exposure.AimsWe sought to quantify the sun radiation exposure received by outdoor rock climbers and assess their sun exposure habits, sun protection behaviors, attitudes, and knowledge regarding skin cancer.MethodsFrom April to June 2021, outdoor rock climbers contacted via email completed an online validated self-reported questionnaire on sun related habits, behaviors, attitudes and knowledge. As a pilot trial, ten participants wore a personal dosimeter during two outdoor climbing weekends in May and November 2021. Ambient ultraviolet radiation (UVR) was also recorded.ResultsA total of 217 outdoor rock climbers (103 women), mean age 36.8 ± 8.8 years (range 20–70 years) and median climbing practice per week of 8 h (IQR 7.5) were studied. Two in three (65.9%) participants reported at least one sunburn event during the previous rock climbing season. Of the survey respondents, 49.3% reported using sunscreen with SPF ≥ 15, 47% wore sunglasses, and 14.3% indicated they reapplied sunscreen every two hours. The median personal UVR dose measured during the two outdoor climbing weekends analyzed was 5.2 (IQR 1.8) and 8.8 (IQR 1.1) standard erythemal doses, respectively.ConclusionsThe high rates of sunburn, the elevated personal UVR measured and the clearly insufficient sun protection practices followed during rock climbing together with unsatisfactory attitudes towards tanning reveal the need to develop explicit sun protection campaigns and educational strategies to reduce the risk of skin cancer among the athletes studied.Graphical abstract

Digitally measuring solar ultraviolet radiation in outdoor workers: A study protocol for establishing the use of electronic personal dosimeters in Portugal.

The rising incidence of skin cancer over the years has made it a significant public and occupational health issue. However, skin cancer is highly preventable, mainly through reduced exposure to solar ultraviolet radiation (UVR), which can be achieved by a variety of individual and collective protective measures and interventions. The relative risk associated with different patterns of exposure to solar UVR differs for the subtypes of keratinocyte cancers (KC). Specifically, whether the exposure is intermittent or continuous, and occurs in an occupational or leisure/recreational setting. The main aim of the study using this protocol is to contribute to raising public and policy awareness on solar UVR-inflicted occupational skin cancers in Lisbon. This will be achieved by performing direct measurements of the solar UVR dose received by outdoor workers using a digital platform. Results will likely contribute to further understanding the risk estimates for keratinocyte cancer estimations in this population. A prospective observational study will be conducted in Lisbon, Portugal. Personal electronic dosimeters (GENESIS-UV system) integrated with a digital platform will be used to assess occupational solar UVR doses of gardeners, masons, and gravediggers of the municipality of Lisbon. Two hundred and ten outdoor workers will be selected to wear the dosimeter for 1 month each, between April and October during their daily working hours. A digital web-based platform that offers private access to information through dashboard visualization will provide information for the outdoor workers and facilitate communication with the participants. The expected results of the overall proposal comprise the occupational solar UVR doses, expressed in standard erythemal dose (SEDs) per day of outdoor work for 7 months. Study data will provide outdoor workers with information on their personal solar UVR exposure during their working hours and an estimate of their risk of developing skin cancer. It is expected that the occupational solar UVR doses of the outdoor workers in Portugal will be above the threshold of 1 to 1.33 SED/day, due to the latitude of Lisbon and the nature of the occupations. The results prospectively should flow into the design of adequate prevention campaigns for skin cancer in outdoor workers.

Occupational Sun Exposure Among Physical Education Teachers in Primary and Secondary Schools in Andalusia, Spain.

Chronic sun exposure and sunburns are the main preventable causes of skin cancer. Due to the nature of their work, physical education teachers are at high risk for occupational skin cancer. This descriptive, cross-sectional study analyzes primary and secondary physical education teachers in Andalusia, Spain. All participants were invited to monitor their ultraviolet (UV) radiation exposure using individual biologic dosimeters and record their photoprotection practices over 3 workdays. The teachers spent an average of 2.7h outdoors and the mean personal UV radiation exposure was 309.9J/m2 per day, a value three times higher than international recommendations. Based on the photoprotection diary, it was determined that classes held outdoors were not scheduled outside the hours with the highest UV index and that the percentage of participants who followed the photoprotective practices of remaining in the shade or wearing a hat during outdoor lessons were less than 20% and 60%, respectively. The results on sun exposure and photoprotection practices show a need for organizational and educational intervention strategies to mitigate sun exposure and increase compliance with photoprotection measures to reduce skin cancer risk among these workers and promote early diagnosis of the disease.

Personal ultraviolet radiation exposure can be determined through a simple modelling approach.

Linked Article: Soueid et al. Br J Dermatol 2022; 186:266–273.

Estimating personal solar ultraviolet radiation exposure through time spent outdoors, ambient levels and modelling approaches.

Evidence on validation of surrogates applied to evaluate the personal exposure levels of solar ultraviolet radiation (UVR) in epidemiological studies is scarce. To determine and compare the validity of three approaches, including (i) ambient UVR levels, (ii) time spent outdoors and (iii) a modelling approach integrating the aforementioned parameters, to estimate personal UVR exposure over a period of 6 months among indoor and outdoor workers and in different seasons (summer/winter). This validation study was part of the European Commission-funded ICEPURE project and was performed between July 2010 and January 2011 in a convenience sample of indoor and outdoor workers in Catalunya, Spain. We developed linear regression models to quantify the variation in the objectively measured personal UVR exposure that could be explained, separately, by the ambient UVR, time spent outdoors and modelled UVR levels. Our 39 participants - mostly male and with a median age of 35 years - presented a median daily objectively measured UVR of 0·37 standard erythemal doses. The UVR dose was statistically significantly higher in summer and for outdoor workers. The modelled personal UVR exposure and self-reported time spent outdoors could reasonably predict the variation in the objectively measured personal UVR levels (R2 range 0·75-0·79), whereas ambient UVR was a poor predictor (R2 = 0·21). No notable differences were found between seasons or occupation. Time outdoors and our modelling approach were reliable predictors and of value to be applied in epidemiological studies of the health effects of current exposure to UVR.

Erythemal ultraviolet radiation exposure of high school rowers in Aotearoa/New Zealand.

Athletes who compete in outdoor sports can receive potentially harmful levels of solar ultraviolet radiation (UVR). Rowing is a popular outdoor sport that takes place during the peak UVR season. Using electronic dosimeters attached to the shoulder strap of the rower's uniform, this study aimed to quantify the real-time solar UVR exposure experienced by high school rowers during competition. We measured personal UVR exposure (PE) during the time spent on the water in order to compete in a single rowing-race (race-time), when rowing administrators are responsible for athletes' wellbeing. Data collection took place in Aotearoa (New Zealand) at Lake Ruataniwha (44.28°S, 170.07°E), during two consecutive rowing seasons (December-February 2018-19 and 2019-20). Analysis of dosimeter data generated from 56 race-times over five regattas revealed a median personal UVR exposure (PE) of 1.15 standard erythemal dose (SED), where 1 SED is defined as an effective radiant exposure of 100 Jm-2. Mean race-time was 46min. Over two-thirds of race-times (69.6%) exceeded the Australian Radiation Protection and Nuclear Safety Agency recommendation of 1 SED being considered safe for most people in a day. An exposure of 1.5-3.0 SED produces perceptible erythema for people with light coloured skin and the lower parameter of 1.5 SED was exceeded in 14 (25.0%) of the race-times. By regatta, the median SED/h ranged from 0.96-2.40 and the median percentage of total concurrent ambient UVR ranged from 17 to 31%. Our results indicate that rowing is a high UVR sport and that races outside of peak UVR times also warrant the use of sun protection even when the UVI<3. Given that acute and cumulative UVR exposure are recognised risk factors in the development of ocular diseases and skin cancers later in life, risk management guidelines for competitive school rowing will be incomplete until a long-term approach to well-being is considered and comprehensive sun protection measures adopted.

Sun Exposure and Physical Activity: The Valuable Role of UV Wearables

Skin cancers are one of the most common types of cancer in the United States [1], and melanoma has steadily increased over the last 20 years. Solar ultraviolet radiation (UVR) is known as the main cause of damaging effects to the skin [1], [2], yet also the most preventable risk factor. Outdoor physical activity, an important health behavior, exposes the body to UVR and is thus ostensibly linked to increases the risk of sunburn, melanoma, and non-melanoma skin cancers [3], [4]. Simultaneously, new UVR sensors can play an essential role in ensuring users gain enough sunlight for Vitamin D synthesis for optimal health. However, accurately monitoring personal UVR exposure is historically complex and costly, and thus minimal research exists at the intersection of personal UVR exposure during physical activity.

Personal Solar Ultraviolet Radiation Exposure of Farmworkers: Seasonal and Anatomical Differences Suggest Prevention Measures Are Required.

Farmworkers are at risk of excess exposure to solar ultraviolet radiation (UVR) during their work activities, especially if they work in geographical areas with high ambient solar UVR levels such as in South Africa. Excess exposure to solar UVR may lead to several negative health effects such as certain cataracts and skin cancer. This study evaluated personal solar UVR exposure of a group of farmworkers to determine if they were at risk of health-related problems due to excess solar UVR exposure. Polysulphone film (PSF) badges were placed on the shoulder, arm, and top of the head of outdoor and indoor farmworkers on a macadamia nut and avocado farm in the Limpopo province for the duration of their daily work shift to evaluate their total daily solar UVR exposure. Sixteen days were assessed for each of the three, high solar UVR seasons, i.e. autumn, spring, and summer. During autumn, farmworkers' arms received the highest solar UVR exposures (geometric mean (GM) = 7.8 SED, where 1 standard erythemal dose (SED) = 100 J/m2, 95% CI 6.1-9.8 SED) while the highest exposures were on the top of the head during spring (GM = 11.6 SED, 95% CI 7.3-17.4 SED) and summer (GM = 13.9, 95% CI 10.4-17.9 SED). Statistically significant differences in solar UVR exposure were found between the body sites during spring and summer but not autumn. The relatively high daily solar UVR exposure levels of farmworkers suggest this occupational group is at risk of excess solar UVR exposure and preventive measures with awareness information to safeguard health is necessary for employers and employees.

Review on Occupational Personal Solar UV Exposure Measurements

During leisure time, people can decide if they want to expose themselves to solar ultraviolet (UV) radiation and to what extent. While working, people do not have this choice. Outdoor workers are exposed to solar UV radiation (UVR) on a daily basis. This may pose a certain health risk, which can be estimated when the personal solar UVR exposure (PE) is known. During past decades, a variety of studies were conducted to measure PE of outdoor workers and our knowledge of the PE of outdoor workers has increased remarkably. As shown by this review, studies clearly indicate that PE of most outdoor workers exceeds the internationally proposed threshold limit value, which is comparable to 1.0 to 1.3 standard erythema dose (SED), respectively, to 1.1 to 1.5 UV Index received over one hour. Besides working in a high UVR environ, monotonic workflow (limited movement, nearly static posture) is a risk factor. In such cases, PE can be higher than ambient UVR. In this review, we provide also a list of milestones, depicting the progress and the most important findings in this field during the past 45 years. However, in many respects our knowledge is still rudimentary, for several reasons. Different measuring positions have been used so that measured PE is not comparable. Few studies were designed to enable the extension of measured PE to other locations or dates. Although the importance of a proper calibration of the measuring devices in respect to the changing solar spectrum was pointed out from the beginning, this is often not performed, which leads to high uncertainties in the presented PE levels. At the end of our review, we provide some key points, which can be used to evaluate the quality of a study respectively to support the design of future studies.

Solar Ultraviolet Radiation and Vitamin D Deficiency on Epstein-Barr Virus Reactivation: Observational and Genetic Evidence From a Nasopharyngeal Carcinoma-Endemic Population.

BackgroundWe investigated the relationship of Epstein-Barr virus viral capsid antigen (EBV VCA-IgA) serostatus with ambient and personal ultraviolet radiation (UVR) and vitamin D exposure.MethodsUsing data from a multicenter case-control study, we included 1026 controls subjects in 2014–2017 in Hong Kong, China. Odds ratios (ORs) and 95% confidence intervals (CIs) of the association between UVR exposure and EBV VCA-IgA (seropositivity vs seronegativity) were calculated using unconditional logistic regression models adjusted for potential confounders.ResultsWe observed a large increase in seropositivity of EBV VCA-IgA in association with duration of sunlight exposures at both 10 years before recruitment and age 19–30 years (adjusted OR = 3.59, 95% CI = 1.46–8.77; and adjusted OR = 2.44, 95% CI = 1.04–5.73 for ≥8 vs <2 hours/day; P for trend = .005 and .048, respectively). However, no association of EBV VCA-IgA serostatus with other indicators of UVR exposure was found. In addition, both circulating 25-hydroxyvitamin D (25OHD) and genetic predicted 25OHD were not associated with EBV VCA-IgA serostatus.ConclusionsOur results suggest that personal UVR exposure may be associated with higher risk of EBV reactivation, but we did not find clear evidence of vitamin D exposure (observational or genetic), a molecular mediator of UVR exposure. Further prospective studies in other populations are needed to confirm this finding and to explore the underlying biological mechanisms. Information on photosensitizing agents, and serological markers of EBV, and biomarkers related to systemic immunity and inflammation should be collected and are also highly relevant in future studies.

Personal ultraviolet radiation dosimetry and its relationship with environmental data: A longitudinal pilot study in Croatian construction workers

ObjectiveThis pilot study aimed to estimate annual occupational ultraviolet radiation (UVR) exposures based on 5 consecutive months of dosimetry measurements in Croatian construction workers and assess its relationship with the environmental data collected during the same period. MethodsFour male construction industry workers from the vicinity of Zagreb (lat. 45.8° N, alt. 128 m) participated in the study. The study was a part of the GENESIS-UV project, attempting to collect long-term dosimetry data for outdoor occupations across Europe. Workers wore personal dosimeters (model X2012–10, Gigahertz, Tuerkenfeld, Germany) on the left upper arm during working hours in the period from June to October 2017. Median exposure assessment period was 57 working days. ResultsEstimates of annual occupational UVR exposure ranged from 76 SED to 976 SED per worker, reflecting large differences in patterns of workers' exposure. Daily UVR doses received by the workers were comparable to the values of other studies at similar latitudes, reaching up to 12 SED in summer months. Measurements of workers with high exposure values (estimated >600 SED/year) showed moderate to high associations with environmental UVR and insolation data (Spearman's correlation coefficient ranging from 0.57 to 0.73). ConclusionsThe results confirmed high occupational exposure of tested Croatian construction workers to solar UVR. However, more data are needed to explain the between-worker variability and develop prediction models with respect to specific work tasks. The use of environmental UVR for predicting long-term exposure should be considered, especially for high exposure tasks.

Clinical Trial Data Management in Environmental Health Tailored for an African Setting.

Clinical trial data management tools are widely available—some free to access and others relatively expensive, particularly for low- and middle-income countries. Such tools also do not always permit adaptation for local conditions nor include options to capture environmental and meteorological data. In the context of climate change and pressing environmental health threats, more studies that aim to assess the impacts of environmental change on public health are being carried out. Here, using freely available software, we tailor-made a clinical trial data management tool that managed all aspects of an intervention-based clinical trial to assess the impact of personal solar ultraviolet radiation exposure on vaccine effectiveness. Data captured and associated procedures included patient data, scheduling, reporting, analysis and data management. Moreover, patient enrolment, recruitment, follow-up and decision-making in response to patient data were managed. Given the multidisciplinary study approach, the tool also managed all environmental and meteorological data for the rural African study site. Application of the tool ensured efficient communication between rural sites, a relatively high overall participant response rate (87%) and minimal loss to follow-up. This study suggests that it is possible to tailor-make a clinical trial data management tool for environmental and public health studies.

Method for Measurements of Terrestrial Ultraviolet Radiation on Inclined Surfaces in Personal Dosimetry Field Studies.

Understanding personal ultraviolet radiation (UVR) exposure is essential for the evaluation of the health risks and benefits; however, personal dosimetry could be challenging in large-scale or/and long-term population studies. Alternatively, personal exposure could be simulated using three-dimensional models and lifestyle surveys together with data on a body position with respect to the sun. These models require a real-time input on local environmental UVR. The main challenge in using this method is retrieval of the diffuse irradiance as it requires an often-expensive tracking of solar position. In this study, a hypothesis that UVR measured on a vertical plane in the north direction can be used in the UK as a proxy for diffuse radiation was tested against direct measurements and compared with models based on solar tracker data in Chilton, UK, (51.57°N) in June-July 2018. The statistical analysis over 17 days under all weather conditions showed that for 45° and 90° tilted surfaces the proposed method performed as well as the best of the models based on solar tracker data. A proposed system could offer a portable and low-cost alternative to measurements of diffuse radiation by solar tracking radiometers for spatial distribution of terrestrial erythema effective UVR in population field studies.

Solar Ultraviolet Radiation Exposure among Outdoor Workers in Three Canadian Provinces.

Solar ultraviolet radiation (UVR) exposure places outdoor workers at risk of skin cancer and exposure is difficult to control. In response, the Sun Safety at Work Canada (SSAWC) project was undertaken (2014-2016). The purpose of this substudy was to characterize the UVR exposure levels of outdoor workers in the SSAWC project. Thirteen workplaces in the provinces of British Columbia, Ontario, and Nova Scotia participated in an exposure monitoring campaign (late summer/early fall 2016). Study participants were workers from power utilities and municipalities. Participants wore a UVR measurement badge (light-sensitive polysulfone plastic) on their wrist, shoulder, or hardhat. Badge calibration and absorbance measurements were performed in the AusSun Research Lab. Personal UVR doses are presented as standard erythemal doses (SED) and compared with the internationally recommended exposure limit (1.3 SED), as well as to the total available UVR by date. Generalized linear models were used to examine determinants of solar UVR for personal UVR dose (for both SED and percent of ambient UVR). Models considered badge placement, date, province, industry, main job task, and the hours spent outdoors. Mean personal UVR dose of participating workers was 6.1 SED (nearly 5× the recommended limit). Just 14% of workers experienced 'acceptable' levels of solar radiation; 10% were exposed at >10 times the limit. In univariate analyses, workers in Ontario had the highest levels (mean 7.3 SED), but even in the lowest exposed province (British Columbia), the mean personal UVR dose was 4.5 SED. Utility workers had double the exposure of municipal workers (10.4 and 5.5 SED, respectively). In the determinants of exposure models, the differences by province were muted, but utility line workers and those in general maintenance had higher predicted exposures. Those who wore their badge on their hardhat also had higher values of SED in the fully adjusted determinants models. Solar ultraviolet overexposure among outdoor workers is a concern, even in a country like Canada with relatively low ambient UVR. Implementation of sun safety programs should be supported in an effort to reduce exposure in this vulnerable group of workers.

Influence of Air Temperature on the UV Exposure of Different Body Sites Due to Clothing of Young Women During Daily Errands.

Clothing is one of the main influencing factors for personal ultraviolet radiation (UVR) exposure. Despite that, little attention was put on this topic till now. In this study, the clothing habits of young females have been investigated in dependence of meteorological conditions. Observations were made from spring to autumn during daylight in the urban region of Vienna, Austria. For this, a scheme dividing the body into six different sections was developed as well as a coding scale that corresponds to the different garments and indicates the body sites that are exposed. It was found that air temperature is the dominating factor for exposure. With increasing temperature, the first area of the body to be exposed to solar UVR is, aside from face and hands, the décolleté, followed by nape, ankles, instep and forearms. Observations further indicate that the frequency of people's being outdoors decreases significantly at temperatures higher than 30°C. This paper provides detailed frequency distributions of uncovered body sites in dependence of temperature. These can be used together with measurements of temperature and UVR to calculate the relative exposure at any time and at many locations, and could help to explain the body distribution of UVR caused skin alterations.

Personal ultraviolet Radiation exposure in a cohort of Chinese mother and child pairs: the Chinese families and children study

BackgroundFew studies in China have examined personal ultraviolet radiation (UVR) exposure using polysulfone dosimetry.MethodsIn this study, 93 mother and adolescent child pairs (N = 186) from two locations in China, one rural (higher latitude) and one urban (lower latitude), completed 3 days of personal UVR dosimetry and a sun/clothing diary, as part of a larger pilot study.ResultsThe average daily ambient UVR in each location as measured by dosimetry was 20.24 Minimal Erythemal Doses (MED) in the rural location and 20.53 MED in the urban location. Rural mothers had more average daily time outdoors than urban mothers (5.5 h, compared with 1.5 h, in urban mothers) and a much higher daily average personal UVR exposure (4.50 MED, compared with 0.78 MED in urban mothers). Amongst adolescents, rural males had the highest average daily personal UVR exposure, followed by rural females, urban females and urban males (average 2.16, 1.05, 0.81, and 0.48 MED, respectively).ConclusionsAlthough based on small numbers, our findings show the importance of geographic location, age, work/school responsibilities, and sex of the adolescents in determining personal UVR exposure in China. These results suggest that latitude of residence may not be a good proxy for personal UVR exposure in all circumstances.

Reproductive factors, exogenous hormone use and incidence of melanoma among women in the United States

BackgroundAlthough the photosensitising effects of oestrogens may increase the impact of ultraviolet radiation (UVR) on melanoma risk, few prospective studies have comprehensively assessed the association between oestrogen-related factors and melanoma.MethodsWe examined the associations between reproductive factors, exogenous oestrogen use and first primary invasive melanoma among 167 503 non-Hispanic white, postmenopausal women in the NIH-AARP Diet and Health Study. Satellite-based ambient UVR estimates were linked to geocoded residential locations of participants at study baseline.ResultsIncreased risk of melanoma was associated with early age at menarche (≤10 vs ≥15 years: HR = 1.25, 95% CI: 0.92, 1.71; P for trend = 0.04) and late age at menopause (≥50 vs <45 years: HR = 1.34, 95% CI: 1.13, 1.59; P for trend = 0.001). The relationship between ambient UVR and melanoma risk was highest among women with age at menarche ≤10 years (HR per UVR quartile increase = 1.29; 95% CI: 1.05, 1.58; P-interaction = 0.02). Melanoma risk was not associated with parity, age at first birth, use of oral contraceptives or use of menopausal hormone therapy.ConclusionsOur findings suggest that increased melanoma risk is associated with early age at menarche and late age at menopause. Effect modification findings support the hypothesis that endogenous oestrogen exposure in childhood increases photocarcinogenicity. Future studies should include information on personal UVR exposure and sun sensitivity.