SAN DIEGO – a finding that might interest consumers and prompt the Food and Drug Administration to continue to allow sunscreens to have labels listing sun protection factors greater than 50.*
“Our study results show pretty definitively that SPF 100 did significantly better than SPF 50 in a real world environment,” , said at the annual meeting of the American Academy of Dermatology.
Dr. Rigel cited data that he and his associates recently published from 199 adults skiing on a sunny March day in Colorado. Participants applied a blinded sunscreen rated at SPF 50 to one side of their face all day and an SPF 100 sunscreen to the other side all day, and the researchers then ran a blinded assessment of images taken of each side at the end of the day. The sunburn on the SPF 50 side exceeded the other side in 55% of skiers, the two sides matched in 40%, and in 5% the sunburn was worse on the SPF 100 side (J Am Acad Dermatol. 2017 Dec 29.).
“The SPF 50 side of the face was 11 times more likely to be sunburned than the SPF 100 side,” and for all the secondary endpoints and different ways of analyzing the data, the SPF 50 was not as effective as SPF 100, Dr. Rigel said in a. Erythema appeared on 41% of the SPF 50–treated sides of participants faces, compared with 14% of the sides treated with SPF 100 sunscreen.
The results followed-up on a report from Dr. Rigel and his associates from 8 years ago that ran a similar comparison of two sunscreen potencies, SPF 85 and SPF 50, in 56 skiers, with similar results showing greater sunburn protection from the higher SPF sunscreen (). In 2011, the FDA proposed a new for SPF labeling that would cap the maximum SPF potency possible of 50, which created a label 50+ to designate unspecified SPF above 50. According to Dr. Rigel, the FDA rejected his 2010 study as documentation of incremental benefit above SPF 50 because of several flaws the agency found with that study, including not tracking sunscreen use by weight. He specifically designed the new, 199-subject study to address that and the FDA’s other concerns.
He and his associates decided to do the study because the FDA said in the monograph that, if the concerns were met, “they would accept the study as definitive,” said Dr. Rigel, a dermatologist at New York University.
The greater protection from SPF 100 sunscreen probably occurs because it’s “more forgiving” when used with inadequate application, he suggested. Allowing labeling that specifies SPF levels greater than 50 would help consumers pick sunscreen formulations that give greater protection, and it would encourage manufacturers to market sunscreens with higher SPF levels.
Dr. Rigel has been a consultant to Castle Biosciences, DermTech, Ferndale, Myriad, Neutrogena, and Novascan and has received research support from Castle and Neutrogena.