The biomedical effects of ultraviolet radiation and their mechanisms

Human and animal health effects of UVR are considered. At the cellular level UVR have been observed to cause changes in the cell division and/or differentiation, the loss of specialized functions, mutations, transformation and death. Most of these effects occur via mechanism that involves DNA damage and induction of pyrimidine dimers. The critical organs for UVR are skin, eye and immune system. In the skin UVR can induce erythema, tanning, vitamin D biosynthesis, keratosis, elastosis, pigment dystrophy and cancer. UVR has immunosuppressive effect, transferable with lymphoid cells, that is critical to the outgrowth of highly antigenic UV-induced tumors. UVR also suppress both contact hypersensitivity and delayed hypersensitivity responses to a variety of antigens. UVR exposure to the eye can induce photokeratoconjunctivitis and plays a significant, role in the etiology of cataracts, corneal and retinal degeneration, pterygium and uveal melanoma. Information about action spectra, biologically effective doses and mechanisms of effects mentioned is presented. Acceptable doses of UVR with regard to damage to skin and eye, recommended in some foreign countries are discusses.