The suit got us thinking: Are we really clear on what sunscreens can and can't do? Maybe not. So we took some of the biggest claims and ran them by experts. You might want to take what they say -- along with the sunscreens they use -- to the beach with you this summer.
Myth No. 1: Sunscreen is all you need to stay safe.
Reality: "Sunscreen is only one part of the sun-protection picture," explains Francesca Fusco, M.D., an assistant clinical professor of dermatology at Mount Sinai Medical Center in New York. "Just slathering it on and doing nothing else isn't going to cut it because, even with sunscreen, there's still up to a 50 percent risk that you'll burn."
You also need to seek shade between 10 a.m. and 4 p.m. when sunlight is strongest; cover up with clothing, a broad-brimmed hat, and UV-blocking sunglasses; do regular skin self-exams; and get a professional skin evaluation annually. (Health.com: How to spot skin cancer )
Myth No. 2: SPF measures levels of protection against both UVB and UVA rays.
Reality: The SPF (sun protection factor) measures only the level of protection against UVB rays. But several of the 16 active ingredients approved by the Food and Drug Administration for use in sunscreens also block or absorb UVA rays, says Warwick L. Morison, M.D., professor of dermatology at Johns Hopkins Medical School and chairman of the Skin Cancer Foundation's Photobiology Committee.
Ingredients include: avobenzone (Parsol 1789), octocrylene, titanium dioxide, and zinc oxide, as well as the recently approved Mexoryl SX. Make sure one of these is in your sunscreen, or look for products labeled "broad spectrum," which means they protect against UVB and UVA rays. (Health.com: Remedies for skin-care problems )
Myth No. 3: Some sunscreens can protect all day.
Reality: "Regardless of the SPF or what the label says, sunscreens must be reapplied every two hours," Fusco says. "The active ingredients in most products begin to break down when exposed to the sun." Only physical blockers such as zinc oxide stay potent after two hours, but not all sunscreens are made with these ingredients.
Myth No. 4: Some sunscreens are waterproof.
Reality: The FDA does not recognize the term "waterproof," so don't count on sunscreen to last through hours of swimming. The agency does recognize "water/sweat/perspiration resistant" (which means a product offers SPF protection after 40 minutes of exposure to water) and "very water/sweat/perspiration resistant" (which means it still protects after 80 minutes).
To be safe, reapply sunscreen after swimming or sweating. (Health.com: UV-protective clothing )
Myth No. 5: A sunscreen can provide "total sunblock."
Reality: "No sunscreen blocks 100 percent of UV rays," Fusco says. An SPF 15 protects against 93 percent of UV rays, SPF 30 protects against 97 percent, and SPF 50 wards off 98 percent. You should slather two tablespoons on your body a half-hour before going outside, so the sunscreen has time to absorb into your skin.