Biological effects and health risk of solar UV radiation exposure

Even if an exposure to artificial UV sources is possible in various occupational activities, solar radiation is certainly the source of UV exposure involving the larger number of workers. UV exposure is related to adverse, but also to beneficial effects: a moderate degree of UV exposure is necessary for the production of Vitamin D, essential for bone metabolism.  On the other hand, an excessive exposure can induce various acute and chronic adverse effects.  Acute overexposures, not rare in an occupational setting, can induce effects to the eye, as acute photokeratitis or acute solar retinopathy, to the skin as sunburn, and to immune system, as activation of some latent virus infections.   Chronic excessive eye UV exposure can induce pterigium or climatic droplet, but the main adverse chronic effect is cataract: some millions of people worldwide are currently blind as a result of UV exposure. Some data support a possible role of UV also in macular degeneration, but data are less conclusive. Chronic skin exposure is related to solar keratoses. Another well known effect of chronic UV sunlight exposure is cancer: epidemiological evidence supports an association of prolonged and unprotected sunlight exposure with squamous cell and basal cell carcinoma (SCC and BCC), and cutaneous malignant melanoma, while evidence is less conclusive for ocular melanoma and lip cancer. IARC has recently included UV radiation (UVA, UVB and UVC and solar radiation) in Group 1 (carcinogenic to humans).   A further cause of concern is the current increase of solar UV exposure, related to stratospheric ozone layer depletion: as an example, it is estimated that each 1% decrease in stratospheric ozone would result in an increase of 0.5% in the number of cataract related to solar UV.