Sunscreens are used to mitigate the adverse effects of sunlight on the skin but are primarily designed to prevent sunburn and damage caused by UVB. The recognized role of UVA in aging has increased, and also the possible role in causing melanoma, and this emphasizes the need to include UVA filters, however, validation is difficult. We have used a novel method to establish the efficacy of sunscreens, by measuring the production of free radicals induced by UVA (which is believed to contribute to aging UVA and changes related to malignant). Electronic resonance spectroscopy was used to detect free radicals directly in human Caucasian skin during irradiation with UV levels comparable to solar intensities. Using this system, the protection achieved by three high factor sunscreen (SPF 20 +) that offer protection from UVA were examined.
Each sunscreen behaved similarly: a recommended application levels (2 mg per cm2) the UV-induced free radicals were reduced by only 55% and about 45% to 0. 5 1. 5 mg per cm2 (0. 5 mg per cm2 was common usage). The factor of free radical protection calculated on the basis of these results was only 2 recommended level of application, which contrasts sharply with the FPS based on erythema (mainly UVB protection indicate) marked by manufacturers (20 +) . The disparity between these two FPS suggests that prolonged sunbathing (encouraged by the use of these creams) can disproportionately increase exposure to UVA and consequently the risk of sun damage induced by UVA. It is clearly established that the UV wavelengths of sunlight are carcinogenic and contribute to the formation of skin malignancies in the form of basal cell carcinoma and squamous and melanoma.