Sun Protection and Sunscreens (cont.)

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Are all sunscreens equally effective against UV radiation?

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No. Some sunscreens protect against only one type of ultraviolet radiation: ultraviolet-B (UVB). Others protect against both types of ultraviolet radiation that reach earth's atmosphere from the sun: ultraviolet-B and ultraviolet-A (UVA). UVB rays account for only 5% of the UV rays reaching the surface of the earth. UVB rays cause sunburn and contribute to aging of skin, skin cancers, and hyperpigmentation. The majority (about 95%) of UV rays that reach earth are UVA rays. While these are less potent than UVB rays, they are also thought to promote skin cancers and skin aging.

Sunscreens that protect against both UVA and UVB, and are thus classified as "broad spectrum," are recommended for everyone. There are new regulations in labeling of sunscreen products that allow consumers to better understand the degree of protection offered by a given product.

How do sunscreens work, and which sunscreen ingredients protect against both types of UV radiation?

Physical sunscreens containing zinc oxide or titanium dioxide protect against UVB and UVA. However, zinc oxide blocks more UV radiation than titanium dioxide and, therefore, is the preferred ingredient. Some chemical sunscreens can also block UVA rays. Octocrylene is a chemical known as a cinnamate that has both UVA- and UVB-absorbing properties, and the benzophenones (such as avobenzone) can also absorb both UVA and UVB rays. In July 2006, the U.S. FDA approved an over-the-counter (OTC) sunscreen preparation known as Anthelios SX that contains the UVA filter ecamsule. Ecamsule is a potent UVA-blocking compound that has been sold in sunscreen products in Canada and Europe since 1993.

Medically Reviewed by a Doctor on 5/23/2014

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