If you've made it to July without getting a painful sunburn, congratulations! Now you have to keep it that way, and it turns out your sunscreen might not help as much as you think. A new study, published in JAMA Dermatology, found that many popular sunscreens don't meet doctors' standards.
Researchers at Northwestern University's medical school looked at 65 of the most popular sunscreens on Amazon, judged by a rating of more than four stars and a high number of reviews. They evaluated each sunscreen based on the American Academy of Dermatology's guidelines: broad-spectrum protection that protects against UVA and UVB rays, an SPF (sun protection factor) of 30 or higher, and water resistance.
The results were scary for anyone who slathers on the stuff before a day at the beach: Around 40 percent of the sunscreens tested didn't meet the American Academy of Dermatology's guidelines, mostly because they weren't water or sweat resistant. That means if you take a dip in the water or get sweaty from the heat, your sunscreen may stop being effective. (Usually, a truly water-resistant sunscreen will stay effective for 40 or 80 minutes in the water.)
Adding insult to sunburn, the study found that people are paying way too much for sunscreen, too. The cheapest product studied cost 68 cents an ounce and the most expensive cost $24 an ounce, even though they offered basically the same levels of protection. People often pay more for a sunscreen because it smells nicer, feels nicer, or is compatible with their skin type, according to the reviewers on Amazon. "You don't want to wear a chalky, greasy, terrible-smelling product, even if your dermatologist recommends it, " lead author Dr. Steve Xu said in a statement. "This gave us insight into what consumers prefer, so it can guide our recommendations and be cost conscious."
The Personal Care Products Council, the trade group that represents many sunscreen manufactures, issued a statement that noted not all sunscreens have to be water resistant, especially if they're makeup or skin care products that happen to have SPF included. And the term "water resistant" may not mean much anyway, according to a Consumer Reports study from May. That report found that nearly half of "water-resistant" products didn't stand up to being dunked in water, and many others didn't provide the SPF promised on their labels.
There was one specific sunscreen that tested well with both Northwestern and Consumer Reports: No-Ad Sport Sunscreen Lotion SPF 50. Not only did it test well, but it's also affordable, at just 72 cents an ounce. So much for your expensive, comically tiny bottle of fancy sunscreen.
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