You may have found yourself staring helplessly at the klingonese on sunscreen products’ labels not knowing what to do. “SPF,” “UV-A,” “UV-B”, “broad spectrum” feel like rocket science to many people.
But things are not as complicated as they may seem. Experts at the Skin Cancer Foundation agreed to lend us a hand on that and explain the mysterious sunblock labels.
The Sun protection factor (SPF) is an indicator of how protective the sunscreen is against UV-B rays, which have been often tied to sunburns and skin cancer incidence. Before releasing a new product on the market, companies test their products on paid volunteers.
At least 10 participants agree to have a UV lamp directed at their skin for researchers to learn how long it takes for their skin to turn red. Next, experts apply a layer of sunscreen on volunteers’ skin and repeat the experiment. If it takes 15 times longer for the skin to turn red again, the new sunscreen will be labeled with a SPF rating of 15. If it takes 30 times longer, the SPF is 30 etc.
Experts also explained what “broad spectrum protection” means. The term indicates that the product protects the skin not only against UV-B rays but also against UV-A ones. UV-A rays have been also linked skin cancer and premature wrinkles.
The broad spectrum protection doesn’t require volunteers. Instead, technicians apply the new sunscreen on a piece of special material and repeat the experiment with the UV lamp. If the product absorbs UV-A rays efficiently, it will be labeled as “broad spectrum.”
Another thing you should be looking for when buying new sunblock is “water resistance.” It is crucial for a sun protective product to have water resistance if you plan to go into the water.
Experts test out the water resistance of a new product in laboratory as well. Human volunteers are asked to apply the sunscreen on their skin and enter a hot tub for a determined time. Next, experts measure if the sunscreen didn’t wash off or lost its efficacy.
Separately, the Skin Cancer Foundation performs additional tests on new sunscreen products. The foundation’s experts are interested in allergic reactions before and after sunlight exposure. If a product doesn’t cause such reactions to at least 20 volunteers within 24 hours it will get the group’s seal of recommendation.
Image Source: Flickr