Systemic absorption of sunscreen after topical application.
Lancet. 1997 Sep 20;350(9081):863-4. PMID: 9310609
A group of nine healthy human volunteers, age 29+/-1.8 years applied commercially available SPF-15+ sunscreen product containing oxybenzone (6 % w/v), octyl methoxycinnamate (7.5% w/v), octyl salicylate (5% w/v), and octocrylene (7% w/v) to the entire surface of their forearms. Estimates were that 13.0 g of sunscreen product was applied to a surface area of 1051 cm2. The unoccluded formulation remained for 12 hr and was then removed with soap and water. The volunteers collected urine just before application and for 48 hr after application. Based on oxybenzone and oxybenzone metabolites recovered in urine, the authors estimated that between 1 and 2% of the applied sunscreen was absorbed over a 10-hour period. Whether the other sunscreen ingredients were also present in the urine was not addressed. Abstract Source: Toxnet.