Sunday, September 6, 2009

High-SPF Sunscreens: Are They Better?

WebMD discusses the pros and cons of high-SPF sunscreens.
By Salynn Boyles
Reviewed by Louise Chang, MD

If you’ve shopped for sunscreen lately, you have probably noticed the proliferation of products with ever-higher sun protection factor (SPF) ratings.

Just a few years ago, it was hard to find a sunscreen claiming an SPF higher than 45. These days, the shelves are lined with products from companies such as Banana Boat, Coppertone, and Aveeno touting SPF ratings of 70+, 80, and 90+.

Neutrogena recently introduced Ultra Sheer Dry-Touch Sunblock SPF 100+.

But is a 100+ or a 90+ sunscreen really that much better than one with an SPF of 15?

SPF 100: Twice as Good As SPF 50?

SPF refers to the ability of a sunscreen to block ultraviolet B (UVB) rays, which cause sunburns, but not UVA rays, which are more closely linked to deeper skin damage. Both UVA and UVB contribute to the risk of skin cancer.

It is a measure of the time it would take an individual to burn in the sun if they were not wearing sunscreen vs. the time it would take with sunscreen on.

“SPF is not a consumer-friendly number,” says Florida dermatologist and American Academy of Dermatology (AAD) spokesman James M. Spencer, MD. “It is logical for someone to think that an SPF of 30 is twice as good as an SPF of 15, and so on, but that is not how it works.”

According to Spencer, an SPF 15 product blocks about 94% of UVB rays, an SPF 30 product blocks 97% of UVB rays, and an SPF 45 product blocks about 98% of rays.

“After that, it just gets silly,” he says.
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