Sun Protection and Sunscreens

  • Medical Author:
    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

  • Medical Editor: William C. Shiel Jr., MD, FACP, FACR
    William C. Shiel Jr., MD, FACP, FACR

    William C. Shiel Jr., MD, FACP, FACR

    Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

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Are all sunscreens equally effective against UV radiation?

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. Because in the U.S., sunscreens are regulated by the FDA as are drugs, it is typically more difficult to gain approval for newer sunscreen products than in countries where sunscreens are legally cosmetics products.

Medically Reviewed by a Doctor on 6/12/2015

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