Solar radiation and human health

Abstract

The Sun has played a major role in the development of life on Earth. In Western culture, people are warned against Sun exposure because of its adverse effects: erythema, photoimmunosuppression, photoageing, photocarcinogenesis, cataracts and photokeratitis. However, Sun exposure is also beneficial, since moderate doses give beneficial physiological effects: vitamin D synthesis, reduction of blood pressure and mental health. Shortage of Sun exposure may be even more dangerous to human health than excessive exposure. Avoiding Sun exposure leads to vitamin D deficiency which is associated not only with rickets and osteomalacia, but also with increased risk of cardiovascular disease, multiple sclerosis, rheumatoid arthritis, diabetes, influenza, many types of cancer and adverse pregnancy outcomes. Solar radiation induces nitric oxide release in tissue and immediate pigment darkening which certainly play important roles, although these are still unknown. Action spectra relevant for health are described. We will also review what is known about spectral and intensity variations of terrestrial solar radiation as well as its penetration through the atmosphere and into human skin and tissue.

Solar Radiation Exposure and Outdoor Work: An Underestimated Occupational Risk

“…Upon acute irradiation, several cytokines are liberated, activated, or synthesized by keratinocytes. They belong to several categories and are responsible for local or systemic inflammatory reactions, such as vasodilatation, edema, and possibly hyperpyrexia [ 4 , 8 , 9 , 10 ]. The peak of UV absorption from DNA occurs at an about 260 nm wavelength; then, the absorption of UV-B rays with longer wavelengths rapidly decreases, and no absorption is detected for UV rays with wavelengths longer than 325 nm.…”

“…The 6-4 pyrimidine dimers are often identified UV-induced DNA alterations. Considering UV-A, DNA photo-damage is more indirect and consequent to oxidation, which induces alterations based on the UV absorption in specific chromophores called 8-hydroxydeoxyguanosine (8-OHdG) and on the formation of DNA-protein crosslinks [ 4 , 8 , 9 , 10 ].…”

“…The main skin reactions to solar ultraviolet radiation exposure are neo-melanogenesis and skin thickening, which are responsible for skin darkening (tanning), which can be interpreted as an adaptive defense mechanism. Long-term exposure induces the complex phenomenon of photo-ageing, related to different UV components, but mainly to chronic UV-A damage [ 8 , 9 , 10 ].…”

A Semiempirical Approach to the Determination of Daily Erythemal Doses

“…The knowledge of the incidence of UVR on the public is of crucial importance for health policies on the mitigation of hazards from inadequate solar radiation exposure (34). That knowledge includes forecasting and completion of solar UVR data, especially for tropical sites where the incidence is the highest (7,8,12,33).…”

Antifungal Drug Plasma Exposures: A Possible Contribution of Vitamin D-Related Gene Variants

“…The two analyzed drugs (sirolimus and tacrolimus) are metabolized by CYP3A4 and showed variations during the year according to VD levels; supporting this, the enzyme induction increases when VD levels are high, leading to reduced drug exposure [ 6 ]. Other factors could impact seasonality: for example, the nitric oxide is released in tissue after solar exposition, leading to a darker skin pigmentation [ 7 ].…”