Sun out, sunscreen on. Recent research in the Journal of the American Academy of Dermatology determined that sunscreens rated SPF 100+ were significantly more effective than SPF 50+, in spite of the U.S. Food and Drug Administration’s stance on the topic.
“In real-world settings, consumers apply sunscreens at densities lower than are used to clinically determine SPF, and the linear dependence of SPF to application density is well-established,” wrote the study’s authors.
The present research put sunscreen ratings to the test under “conditions of actual use.” Testing took place in Vail, Colorado, wherein subjects wore their normal quantities of both an SPF 100+ and SPF 50+ sunscreen simultaneously during a day of downhill skiing.
The study’s 199 participants (healthy men and women ≥ 18 years old) spent an average of 6.1 ± 1.3 hr in the sun. Dermatologists assessed erythema (superficial skin redness) of the treated areas separately on the day following exposure. These erythema scores were then compared to any sunburn between treatment areas to measure comparative efficacy.
Investigator-blinded evaluations found that:
- 55.3% of subjects were more sunburned on the SPF 50+ side than the SPF 100+ side, while only 5% were more sunburned on the SPF 100+ side; and
- 40.7% experienced increased erythema on the SPF 50+ side, compared with 13.6% on the SPF 100+ side.
The authors noted that a single-day exposure does not show the benefits of longer-term protection.