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New Testing Method May More Accurately Show Effective Sunscreens

Posted: January 21, 2009

Looking directly at the expression of the p53 gene may be a more accurate way of testing how well a sunscreen protects against UV damage, according to a recent study. Currently the sunscreen industry uses an SPF (Sun Protection Factor) value to communicate the efficacy of a product to consumers. However, SPF is a measure of the protection against UVB-induced erythema (skin-reddening) and says nothing about protecting against UVA rays, or the actual UV-induced DNA damage. Now a recent report published in the latest edition of the International Journal of Dermatology suggests an in vivo test using p53 expression as a way of judging sunscreen efficacy.

Guardian of the genome

The expression of the p53 protein, which study author Dr. Marko Lens describes as the ‘guardian of the genome’ as it plays a role in DNA repair and apoptosis, is higher in cells that have undergone some kind of external stress.

In epidermis not exposed to UV light p53, levels should be almost undetectable. Similarly, if the skin is well protected against UV radiation, levels of the protein should be very low, explained Lens. “Thus, p53 could be used as a sensitivity endpoint to evaluate efficacy of the sunscreen in protection of the skin against UV-induced DNA damage,” he said.

The study used 19 volunteers with fair skin (type II according to the Fitzpatrick scale), 5 male and 14 female. Two previously unexposed areas on the skin of the volunteers were treated with an SPF 15 sunscreen and two were left untreated.