What You Don't Know About Sunscreen - And You Should

By CODY FENWICK (Patch Staff)

WILMINGTON, MA - As the summer season approaches, people will be spending more time out in the sun. And for those who listen to the warnings dermatologists have been stressing for years, this means one thing: They'll be lathering themselves in gallons and gallons of sunscreen.

Sunscreen, though, isn't what it used to be — nor is the advice on how to use it.

“I recommend an SPF of around 30, as long as you’re reapplying it every hour, hour-and-a-half when you’re outdoors,” Lauren Ploch, a dermatologist from the Georgia Dermatology and Skin Cancer Center, said.

This is pretty standard advice, echoing the American Academy of Dermatology's recommendations. SPF, which stands for “Sun Protection Factor,” measures how protective sunscreen is against ultraviolet B (UV-B) light, which is the segment of the sun’s rays that causes sunburns. The higher the number, the more the protection.

But more important than the SPF number are the words "broad spectrum."

While a sunscreen without those words will protect against sunburn, unless that sunscreen also includes "broad spectrum protection," it'll do nothing to protect against ultraviolet A (UV-A) light, which has a much longer wavelength and penetrates deeper into the skin. It can also cause skin cancer.

“What you want to look for is ‘broad spectrum,’” Ploch said. Sunscreen with broad spectrum protection blocks both UV-A and UV-B light, which means you’ll reduce your risk of sunburn as well as skin cancer.

(Sunglasses, too, should be labelled as providing UV-A and UV-B protection as well.)

In 2012, the Food and Drug Administration changed its rules to reflect the importance of UV-A protection. Now, any sunscreen that is SPF 15 or above, and carries the label "broad spectrum," has to provide protection both from both UV-A and UV-B light. Any sunscreen SPF 14 or below, or that isn't labelled "broad spectrum," is primarily only useful for protection from UV-B light and against sunburns.

"SPF does not currently correlate with UV-A protection," Ploch said. "Other countries have started providing measurements for UV-A protection on their products, so the U.S. may follow suit over time."

SPF numbers currently reflect a simple metric. Supposedly, if you could stay in the sun for 10 minutes without getting a sunburn, a sunscreen with an SPF of 15 would increases the length of time you can stay out in the sun by 15 – so you should be able to stay in the sun for 150 minutes without getting burned.

Yet this is misleading, because dermatologists recommend reapplying sunscreen at least every 2 hours, if not more frequently. So even if a sunscreen with SPF 50 could theoretically protect you for up to 500 minutes, you should still be reapplying after 120 minutes.

This doesn't mean there's no difference between SPF 15 and SPF 50. SPF 50 should prevent more UV light from affecting your skin.

The FDA also suggests that any measurement above SPF 50 is unlikely to be meaningful.

Sunscreen manufacturers are no longer allowed to claim their products are "waterproof," because none truly is. They can claim that their sunscreens are water resistant for either 40 minutes or 80 minutes, after which point the sunscreen should be reapplied.

Yet there's good reason to be suspicious of some of these claims as well. A new study published by Consumer Reports found that nearly half of all sunscreens didn't live up to their SPF label when after users went in the water, even though they claimed to be water resistant.

This is the fourth year in a row that Consumer Reports has found a similar results, and it has sent its findings along to the FDA for review.

The editors of the study recommend choosing a sunscreen with an SPF of 40 or higher, so even if it turns out to be less protective than the label suggests, it will most likely be above the recommended minimum of SPF 30.

Physical blockers vs. chemical blockers

Even when limiting your options to those sunscreens with SPF 30 and above with broad spectrum protection, there are many types to choose from. So what kind specifically should you use?

There are two basic kinds of sunscreens: physical blockers and chemical blockers. While physical blockers use minerals to deflect the UV rays away from the skin, chemical blockers absorb and filter the the light to prevent its damaging effects.

Preferences between the two types will vary. Some people like the longer-lasting and less artificial physical blockers; others choose chemical blockers because they feel less greasy and are easier to apply.

“The best sunscreen is the one that you’ll actually put on your skin,” Melissa Piliang, a dermatologist with Cleveland Clinic, said. “If it feels gloppy and goopy and gives you a white film on your skin, you’re not going to like putting it on very much.”

“I prefer physical blockers: those are zinc oxide and titanium dioxide,”Ploch said. “They don’t get as absorbed into the skin as easily, they do stay on the surface and they tend to be thicker and whiter, but they provide better protection.“

However, both forms have potential drawbacks. Consumer Reports found the majority – 74 percent – of the physical blockers they tested failed to match their labelled SPF.

On the other hand, some researchers have raised worries about oxybenzone, a common ingredient in chemical blockers. Though no studies have linked it to harms in human health, it is believed to be a potential hormone disruptor, and it's not clear what long-term effects it might have.

The FDA has also raised worries about spray-on sunscreen, primarily because the risks associated with inhaling the mist are unknown.

Despite all these considerations, dermatologists still believe it's better to use sunscreen than risk overexposure to the sun.

And even with meticulous use of sunscreen, experts recommend limiting time in the sun. You may still be getting a tan even while wearing sunscreen, and that means the ultraviolet light is affecting your skin.

“Any ultraviolet-induced tan, whether it’s from the sun or from a tanning bed, is a sign that you’ve had sun damage to your skin," Piliang said.

Photo Credit: Charlotte via Flickr (edited)