Sunbathers' application of sunscreen is probably inadequate to obtain the sun protection factor assigned to the preparation.
The sun protection factor (SPF) is a ratio that estimates the protective efficacy of a sunscreen against sunburn. The generally accepted methods used to determine the SPF of a sunscreen require that the formulation be applied in a thickness of 1.5 mg/cm2 (Deutsches Institut für Normung) or 2 mg/cm2 (US Food and Drug Administration). The applied thickness of a sunscreen is important for the degree of photoprotection. Forty-two volunteers on a beach applied their own sunscreen all over the body. The amount of the applied sunscreen was on average 0.5 mg/cm2. This indicates that the labelled SPF is probably considerably higher than the obtained degree of protection against sunburn.
Bech-Thomsen
N
N
Department of Dermatology, Rigshospitalet, Copenhagen University Hospital, Denmark.
Wulf
H C
HC
D000293:Adolescent; D000328:Adult; D002648:Child; D005260:Female; D006370:Heliotherapy; D006801:Humans; D008297:Male; D013471:Sunburn / Q000517:prevention & control*; D013473:Sunscreening Agents / Q000008:administration & dosage*
D013473:Sunscreening Agents