The study goes on to note that human exposure to oxybenzone “has not been associated with adverse health effects” and that sunscreen is an important tool to protect against sunburn and skin cancer. But the researchers said further study was needed to determine whether the chemical had any meaningful effect on the body.

Image Credit... Stuart Bradford

“What’s the meaning of it?” said Dr. Rigel, who has consulted for sunscreen makers. “Nobody’s seen any problems from years of these agents being used. To call it dangerous is misleading.”

A few animal studies have raised concerns that oxybenzone could disrupt endocrine functions. Several researchers say that this is a theoretical concern and that no such effect has been shown in humans.

Another study, published two years ago in Free Radical Biology and Medicine, raised troubling concerns about what happens when sunscreen is absorbed into the skin and reacts with the sun. The report suggested that under certain conditions, sunscreens with oxybenzone and other ultraviolet filters could lead to free-radical damage to the skin, a process that in theory could lead to skin cancer. The study used laboratory models of skin, so some researchers say it is not a reliable indicator of what happens in people.

But the authors noted that the damage occurred only when ultraviolet light reached sunscreen that had penetrated the skin. The solution, they say, is to keep applying sunscreen to block out the UV rays.

“It may seem counterintuitive, but by reapplying sunscreen we protect ourselves from the UV light reaching any of the UV-filters that may have penetrated to the skin,” said Kerry M. Hanson, the lead author of the report and a senior research scientist at the University of California, Riverside. “At this point, I don’t think there’s enough evidence to firmly claim that sunscreens containing oxybenzone are unsafe.”