Many popular sunscreens do not adhere to the water-resistant AAD criteria.
Exposure to ultraviolet (UV) light is the most preventable risk factor for all skin cancer types. The American Academy of Dermatology (AAD) recommend that to be protected from the sun's harmful UV rays, a sunscreen that offers broad-spectrum protection against UVA and UVB rays - that is, SPF 30 or higher and water-resistant - should be used every day.
Consumer reviews on websites can sometimes give a good indication of the quality and reliability of a product. However, results from an article published online by JAMA Dermatology questions if sometimes consumer reviews can do more harm than good.
Shuai Xu, M.D., M.Sc., of Northwestern University Feinberg School of Medicine in Chicago, IL, and co-authors searched the keyword "sunscreens" on the U.S. retailer Amazon.com in December 2015.
The team selected the top 1 percentile of sunscreen products according to an average consumer review of four stars or greater. They also collected descriptive data including SPF strength, price, and active ingredients, in addition to the top five most helpful and critical comments for each product.
Of the 6,500 products that were categorized as "sunscreens," the top 65 were chosen for analysis.
The sunscreen products had a median price of $3.32 an ounce and a median SPF of 35, with 89 percent of sunscreens being SPF 30 or higher. Of the products, 92 percent claimed to be broad-spectrum, and 62 percent were labeled as water or sweat resistant. Creams were the most common sunscreen vehicle, followed by lotions and sprays.
Many products did not conform to water-resistance criteria
Water exposure reduces the effectiveness of a sunscreen when a person sweats or is immersed in water. Water-resistant sunscreen is effective for up to 40 minutes in water, and very water-resistant sunscreen is effective for up to 80 minutes in water.
A total of 40 percent of the highest rated sunscreens on Amazon.com did not adhere to AAD guidelines, mostly due to lack of water and sweat resistance.
Consumers identified positive and negative features of a sunscreen product most commonly by cosmetic elegance attributes, such as "absorbs well," "nice smell," "too thick," "greasy," rather than how effectively the sunscreen product performed.
According to the article:
"Dermatologists should balance the importance of cosmetic elegance, cost, and AAD guidelines for sun protection in making their recommendations to consumers."
Limitations of this study include the fact that the source data represent 9 percent of all sunscreen sales and that generalizability may be limited because of the lack of reviewer demographic information.
Most of the products analyzed claimed additional product features in addition to sun protection. The authors note that consumers should be advised that labels such as "safe for sensitive skin," "preservative free," or "noncomedogenic" are marketing mechanisms and are not performance standards, such as SPF, that are regulated by the Food and Drug Administration (FDA).
"Dermatologists should counsel patients that sunscreen products come with numerous marketing claims and varying cosmetic applicability, all of which must be balanced with adequate photoprotection," the study concludes.