Four sunscreen active ingredients were absorbed systemically at plasma concentrations exceeding the FDA threshold for waiving additional safety studies

This FDA-conducted randomized clinical trial assigned 24 healthy volunteers to apply one of four commercially available sunscreen formulations (spray, lotion, or cream) under maximal use conditions (75% body surface area, four times daily). Blood samples showed that avobenzone, oxybenzone, octocrylene, and ecamsule all exceeded the FDA's 0.5 ng/mL threshold for systemic absorption after just one day of use. The study did not conclude that sunscreens are unsafe, but demonstrated that further safety studies are warranted. It was widely cited in debates about mineral vs. chemical sunscreen formulations.

U.S. Food and Drug Administration