Protection against Ultraviolet Irradiation

Measured total column ozone has fallen between about 1970 and 1994. Ultraviolet irradiation increases at the surface of the earth due to ozone depletion should peak at about 15% in midlatitudes. The incidence of harmful health effects of UV radiation can be expected to rise, eventually, at midlatitudes. Public health action is still necessary to reduce sun exposure, increase protection against the sun, and develop clear policies on the action that should be taken on early detection and treatment of skin cancers (Armstrong, 1997). 

Various stimuli, including ultraviolet irradiation of melanocytes, cause increased synthesis of melanin with a resultant tanning0 and added protection against sunburn. 

The sample irradiated at — 196° C in the presence of air gave the same spectrum as that under vacuum. This sample, however, gave the spectrum characteristic of peroxy radicals at about — 68° C. An effect of oxygen on radical formation on irradiation with light of 300 nm was also reported (67). Protection against radiation damage in polymethylmethacrylate by ultraviolet light was also reported (98). 

The ability of lycopene to act as an antioxidant and scavenger of free radicals is frequently cited as the most likely mechanism that could account for the hypothesized beneficial effects on human health.Supporting this theory, protection against oxidative stress has been shown in parallel with a preferential destraction of lycopene relative to P-carotene in a study of human skin irradiated with ultraviolet (UV) light. Further, the ability of carotenoids to act as antioxidants has been hypothesized as the mechanism underlying the protection of the human retina from photooxidation, a process that over time can result in the pathologies of age-related macular degeneration (AMD) and cataracts. ... 

In 1924, the mystery of how sunlight could prevent rickets was partially solved. Dr. Harry Steenbock of the University of Wisconsin and Dr. A. Hess of Columbia University, working independently, showed that the antirachitic activity could be produced in foods and in animals by ultraviolet light. The process, known as the Steenbock Irradiation Process was patented by Steenbock, with the royalties assigned to the Wisconsin Alumni Research Foundation of the University of Wisconsin. Subsequent research disclosed that it was certain sterols in foods and animal tissues that acquired antirachitic activity upon being irradiated. Before irradiation, the sterols were not protective against rickets. 

Third-generation cationic emulsions were suggested as drug carriers for topical use in the skin. It was found that a-tocopherol-loaded cationic emulsion was able to prevent oxidative damage of cultured fibroblast cells [196], In addition, the same cationic formulation was able to protect rat skin against oxidative stress induced by ultraviolet (UV) irradiation significantly better than either the corresponding anionic emulsion or the cationic blank emulsion, as measured with a noninvasive... 

M.P. Lesser, W.R. Stochaj, D.W. Tapley, J.M. Shick (1990). Bleaching in coral reef anthozoans Effects of irradiance, ultraviolet radiation, and temperature on the activities of protective enzymes against active oxygen. Coral Reefs, 8, 225-232. 

Flavonoids, due to their ability to absorb ultraviolet (UV) radiation, can protect DNA (Deoxyribonucleic acid) from the damage caused by UV radiation. This effect is one of the physiological functions proposed for the flavonoids in plants [57], In studies performed with UV-B irradiated plasmids, both naringenin and rutin showed protecting activity against DNA damage, induced by UV radiation [58], Besides a direct protection,... 

With suitable protection of personnel against the effects of ultraviolet radiation, in a flask wrapped in black paper to protect it from light, a quantity of purified acrylic acid dissolved in two volumes of ethanol is sparged with oxygen-free nitrogen for 2 hr to eliminate oxygen. Benzoin (at a level of 13 mg per 1 gm of monomer) is added as a photosensitizer and rapidly dissolved. The solution is cooled at -78 C and irradiated at a distance of 10 cm with a Phillips SP-500 lamp, which is said to be nearly monochromatic at a wavelength of 360 nm. 

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