Application density for aerosol sunscreen is higher than that of lotion in practical use, according to a cross-sectional study.
“Based on our results, spray sunscreen may provide higher but still inadequate levels of UV protection than other sunscreen vehicles but with a considerable amount of waste,” Lindsey Broussard, MD, of the department of dermatology at the University of Colorado Anschutz Medical Campus, told Healio Dermatology. “Although the American Academy of Dermatology released application guidelines on aerosol sunscreen, the lack of consumer safety concerns reported by the FDA regarding aerosol sunscreens may affect the confidence by which dermatologists recommend this mode of delivery and may result in inadequate application by patients.”
Fifty-nine participants from the 2018 Colorado Cancer Coalition meeting completed self-administered questionnaires and were instructed to apply 30 SPF spray sunscreen “as they normally would” to an absorbent pad on their forearm while indoors. Participants’ elbow and forearm radius and forearm length were measured to determine forearm surface area, whereas the amount of sunscreen applied was determined by the weight difference of the pad before and after application. Area density of sunscreen was equal to the amount of sunscreen used on the surface area of the volunteer’s forearm.
The average sunscreen application density was 1.43 mg/cm2 with a median of 1.19 mg/cm2 (standard deviation, 1.64) — slightly higher than sunscreen lotion in practical use, which in a previous study (Novick R, et al. Photodermatol Photoimmunol Photomed. 2015;doi:10.1111/phpp.12171) had a mean application density of 1.1 mg/cm2 and median density of 0.39 mg/cm2 to 1 mg/cm2. Additionally, 56% (standard deviation, 1.64) of the spray sunscreen was lost to the environment, despite the absence of outdoor factors like wind.
“Sunscreen users should be aware that the average consumer does not apply an adequate sunscreen thickness to benefit from the SPF reported on a sunscreen bottle,” Broussard said. “Application density for aerosol sunscreen is relatively high on the arm, suggesting further research on full body self-application of aerosol sunscreen would benefit both providers and consumers.” – by Eamon Dreisbach
Disclosures: The authors report no relevant financial disclosures.