Estimation of exposure durations for vitamin D production and sunburn risk in Switzerland

• DOI: 10.1038/s41370-019-0137-2
• Publication Date: 2019-04-16T16:05:17Z
• Authors: A. Religi; C. Backes; A. Chatelan; J.-L. Bulliard; L. Vuilleumier; L. Moccozet; M. Bochud; D. Vernez
• Keywords: Adult; Male; 0301 basic medicine; Skin Neoplasms; Adolescent; Infant, Newborn; Infant; Sunburn; Middle Aged; 3. Good health; Young Adult; 03 medical and health sciences; Melanoma, Cutaneous Malignant; Child, Preschool; Dietary Supplements; Sunlight; Humans; Female; Seasons; Vitamin D; Child; Melanoma; Switzerland

Although overexposure to solar ultraviolet radiation (UVR) is responsible for cutaneous melanoma and epithelial skin cancer and can cause negative health effects such as sunburn, a "little and often" exposure regime is often suggested to produce naturally recommended vitamin D levels, being essential for skeletal health. This study aimed to quantify solar UV doses needed to trigger 1000 International Units (IU) vitamin D doses and, at the same time, producing sunburn in Switzerland. Solar UV erythema irradiance (in mW/m2) measured at four meteorological stations in Switzerland for the period 2005-2017 were used to evaluate effective solar UV radiation producing 1000 IU vitamin D doses in skin phototype II and III individuals. Daily solar UV exposure durations (in minutes) needed to produce vitamin D with limited sunburn risk were estimated while considering mean vitamin D food intake of the Swiss population and seasonal skin coverage. In summer and spring, with 22% of uncovered skin, 1000 IU vitamin D doses are synthesized in 10-15 min of sun exposure for adults. Exposure durations between erythema risk and 1000 IU vitamin D production vary between 9 and 46 min. In winter and autumn, the recommended vitamin D production without sunburn risks often unachievable, since up to 6.5 h of sun exposure might be necessary considering 8-10% of uncovered skin surface. The vitamin D food intake only represented 10% of the recommended vitamin D production and remained unchanged throughout the year. These findings might clarify why vitamin D deficiency is common in Switzerland. Moreover, exposure durations between recommended vitamin D and increased sunburn risk might only differ by few minutes. Without additional oral vitamin D supplementation, daily doses of vitamin D (1000 IU) are not reachable in autumn and winter months in Switzerland.