Systemic absorption of sunscreen after topical application

Abstract

Sunscreens are widely used to avoid sunburn, photoageing, and skin cancer, and to minimise various photosensitivities and phototoxicities. However, sunscreen products are only routinely tested for their ability to delay the onset of erythema (sunburn) in skin exposed to ultraviolet (UV) radiation. Regulatory agencies differ in the requirements for the approval of sunscreening agents. In the USA, sunscreens are regarded as drugs 1 USA Food and Drug Administration.Sunscreen drug products for over the counter human use: tentative final monograph. Fed Reg. 1993; 58: 28194-28302 Google Scholar whereas in Europe they are termed cosmetics. It is often assumed that little or none of a topically applied substance is absorbed into the systemic circulation. We show that substantial amounts of an applied sunscreen, oxybenzone, are absorbed and subsequently excreted in human urine. Oxybenzone has low acute toxicity in animal studies 2 Cosmetic Ingredient Review.Final report on the safety of benzophenone-1, -3, -4, -5, -9, and -11. J Am Coll Toxicol. 1983; 2: 35-77 Google Scholar yet little is known about its chronic toxicity and disposition after topical application in people. Oxybenzone is a benzophenone derivative commonly used throughout the world to make sun-products with especially high sun protection factors (SPF). It belongs to a small group of UVA blocking agents that include methyl anthranilate and butylmethoxydibenzoyl-methane, which is the UVA sunscreen of choice in Europe.