It is often said that application methods used by consumers are often insufficient for ultraviolet protection based on the labelled sun protection factor (SPF). However, high-SPF sunscreens (sunscreens with SPF 70 and above) may offer more protection even when applied in insufficient amounts. Sunscreens with higher SPF also offer additional benefits when applied in adequate recommended amounts.

The sunscreens in use today are durable even after considerable physical activity and exposure to water, which is reflective of the fact that reapplication intervals may be extended as compared with current recommendations. A study was recently performed to gauge the durability of 2 sunscreens with different SPFs currently in use. In a randomized study including 24 participants, the durability of 2 sunscreens with different SPF protection, currently in use, over 8 hours under simulated real-life conditions was assessed. In the study, two current SPF-15 and 70 sunscreens were applied to test spots on each participant’s back.

The study resultsrevealed that participants in both dose study groups demonstrated only a 15-40% overall reduction in their SPF protection, 8 hours after the application. The study group receiving half the FDA test concentration of sunscreen achieved approximately half or led the labelled SPF. At 8 hours, the test sites receiving SPF 70 maintained an average SPF more than 64 (2 mg/cm2 application) and 26 (1 mg/cm2 application). The authors also suggested that the sunscreen with higher SPF sustained a skin cancer-protective level of SPF even after extended use.

References

1. Yang HO, Stanfield J, Cole C, Appa Y, Rigel D. J Am AcadDermatol. 2012; 67(6): 1220-7.
2. Ouyang H, Meyer K, Maitra P, daly S, Svoboda RM, Farberg AS, Rigel DS. J Drugs Dermatol. 2018; 17(1): 116-7.