We analyzed data from the first National Health and Nutrition Examination Survey Epidemiologic Follow-up Study to test the hypothesis that vitamin D from sunlight exposure, diet, and supplements reduces the risk of breast cancer. We identified 190 women with incident breast cancer from a cohort of 5009 white women who completed the dermatological examination and 24-h dietary recall conducted fr...

Aim of this study was to monitor the solar ultraviolet-B intensity and to compare the phototoxic effect of different intensity of natural and artificial ultraviolet-B on human red blood cells in presence of compounds as riboflavin and chloroquine. Photohemolysis of erythrocytes was studied under natural solar radiation and artificial ultraviolet-B radiation of 312 nm. Monitoring of solar ultrav...

The major source of vitamin D in humans is ultraviolet B (UVB) radiation in sunshine. It has been estimated that vitamin D production in skin provides between 80-100% of the body’s vitamin D requirements [2], and that food sources play a lesser role. Vitamin D is produced when UVB radiation reaches 7-dehydrocholestol in the skin, and there are a number of personal and environmental factors that...

Background: Astronauts will be exposed to both chronic space radiation and acute high doses of energetic radiation of solar particle events in long-term deep space missions. The application of radioprotectors in space missions has basic limitations such as their very short time window as well as their acute toxicity and considerable side effects. The aim of the present study was to investigate ...

When absorbed, a photon of a given energy has the same chemical and biological effect whether it comes from the sun or from an artificial, man-made source like a sun bed. If the spectrum and intensity of a sun bed are the same as those of the sun, the biological effects will be exactly the same. The main difference between radiation from sun and sun beds is that sun beds emit less visible light...

The sun is the most important source of visible and ultraviolet (UV) radiation. Even though the distance from the sun to the Earth is large – about 150×10 km – the fluence rate of solar radiation on Earth, the solar constant, is about 1 360 W/m 2 . Approximately 40% of this radiation is reflected back into space. The remaining 60% is the driving force of all life on Earth. A number of pigments ...

The research objective was to gather and collate data that will enable dermatologists to quantify exposure to solar radiation so that they can give accurate advice to patients using heliotherapy, thereby minimising harm from sun exposure. Other patients can also be advised regarding ultraviolet index (UVI) and sun safety. The concept of minimal erythema dose per hour (MED/h) may be useful in fu...

Humans obtain vitamin D from conversion of 7-dehydrocholesterol in the skin by ultraviolet B (UVB) radiation or from dietary sources. As the radiation level is insufficient in winter, vitamin D deficiency is common at higher latitudes. We assessed whether vernal solar UVB radiation at latitudes 61°N and 67°N in Finland has an impact on serum 25-hydroxyvitamin D [S-25(OH)D] concentrations. Twent...

Introduction Many epidemiologic studies indicate that cancer mortality rate tends to increase at higher latitudes. One proposed hypothesis explaining this geographical gradient is that vitamin D, which is produced after exposure to solar radiation, has anti-carcinogenic effects. However, the association between solar radiation and cancer risk is not fully explained. The Hypothesis A number of r...