Skin cancer expert gives the 411 on sunscreen

CINCINNATI—Putting on the sunscreen has, or should if it isn’t already, become part of our daily regimen, especially during the summer months when the sun shines more often.

However, with so many types of sunscreen on the market today, it’s hard to know the differences in how they work and the application strategy you should use.

For Melanoma Awareness Month, Adam Ingraffea, MD, a clinical assistant professor and associate program director in the University of Cincinnati’s Department of Dermatology and a UC Cancer Institute and UC Health dermatologist, answers questions about sunscreen, its components and what kind of sunscreen could fit your needs.

What is SPF, and what level of SPF should you look for in a sunscreen?
“SPF, which stands for sun protection factor, is a way to measure a sunscreen’s ability to block UV-B radiation. For example if it takes 20 minutes for your unprotected skin to start turning red, using an SPF 15 sunscreen prevents reddening for 15 times longer—about five hours. The higher the number, the more UV-B radiation it is able to block. Although no sunscreen is able to block all UV-B radiation, an SPF-50 sunscreen can block up to 98 percent of incoming UV-B. However, relying only on the SPF number is not enough to prevent UV damage. In the first place, sunscreens only provide their maximum protection for about two hours; after that, they start to break down and lose effectiveness. Secondly, SPF only measures protection from UV-B radiation. We know that UV-A radiation also causes damage to the cells of the skin. This damage can build up without the skin ever turning red.”

How do you select a sunscreen? Do the wipes, sprays, gels, sticks, powders and oils now available work in the same way as traditional sunscreen? Is there a time when one is better than another?
“Pick a sunscreen that is broad spectrum, provides protection against UV-A and UV-B radiation, has an SPF of 30 or higher and is comfortable and convenient to use. Having a high-quality, high-SPF sunscreen that costs $20 for a bottle is not helpful if it is messy and uncomfortable and never gets used. There are many different ingredients approved for use in sunscreens. Many of the popular sunscreens combine chemical with physical blockers to provide broad spectrum protection. The keys to successful sunscreen use are to use enough—one ounce per application—use it often and reapply it frequently, every two hours when exposed to intense UV light.”

Is there a difference between “waterproof” and “water-resistant”?
“Under new rules introduced by the FDA last year, sunscreens can no longer claim to be waterproof. Sunscreens are now labeled as having either 40- or 80-minute water resistance. This change was made to emphasize to the public that sunscreens have only limited ability to resist water and need to be reapplied more frequently when users are in the water. Bottom line is that there is no such thing as waterproof sunscreen,”

What is the difference between sunscreen and sunblock?
“Sunscreen uses chemicals to absorb ultraviolet light before it hits the skin, while sunblock uses minerals to reflect the light away from the skin. Some of the popular sunscreens sold contain a mixture of chemical and physical blockers. In general, sunblock has a thicker consistency and is more difficult to apply than sunscreen. When using either a sunscreen or a sunblock, it is important that they be applied at least 30 minutes before sun exposure to allow full protection.”

When should you use a sunscreen, and how often should you apply/reapply?
“Sunscreen use is recommended on a daily basis for everyone over the age of 6 months. Even if you work inside, you are still being exposed to UV-A radiation through car windows, windows in your office and the time you spend outside. UV-A radiation causes damage to the DNA of skin cells and degrades collagen in the skin, causing signs of premature aging. If a person works outside or is involved in an outdoor activity, it is especially important to apply sunscreen 30 minutes before the event and then re-apply every two hours.

“No matter what, it’s always important to use an SPF-30 or higher sunscreen, especially when you’re going to be out in the sun for long periods of time, and bring a hat, sunglasses or other protective clothing along as well,” he says, adding that one should never use indoor tanning booths. “Skin cancer is by far the most common of all cancers, but by being cautious, one can reduce his or her chance of developing it.”

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