Today, researchers at the FDA revealed the results of a small clinical trial designed to test how four of the most common sun-filtering molecules on the market behave after they’ve been sprayed on and rubbed in. The results, published in the journal JAMA, show that contrary to what sunscreen manufacturers have been saying, UV-blocking chemicals do seep into circulation. Now, don’t panic and toss your tubes. There’s no evidence yet that they’re doing anything harmful inside the body. But the revelation will have serious impacts on sunscreen manufacturers going forward, and may change what options you’ll find on drugstore shelves before the year is out.
“Everyone had always thought that because these are intended to work on the surface of the skin that they wouldn’t be absorbed, but they are,” says Theresa Michele, director of the FDA’s division of nonprescription drug products, and coauthor on the FDA-funded study. Her team found that it took only a few hours after the application of sunscreen for the photoprotective chemicals to infiltrate the bloodstream and shoot up to concentrations above the FDA’s toxicology threshold that triggers further safety testing.
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The fact that these sun-filtering molecules do penetrate into the circulation system does not on its own mean that such ingredients are unsafe. “There might be nothing, and that would be great,” says Kanade Shinkai, a dermatologist at UC San Francisco and editor in chief of JAMA Dermatology. “But the problem is that we just don’t know.” The bottom line, she says, is that although the evidence is irrefutable that the sun causes skin cancer, scientists know a lot less about sunscreen chemicals’ relative risks and benefits.
There's more at the link.
This is particularly worrying to me, in that I can see the long-term effects of sun on my forearms and other areas of skin. Exposed to the burning African sun for years as I was, it took its toll; and it would have taken a greater one if it wasn't for large quantities of sunscreen, liberally applied. Now I wonder whether the sunscreen might not have posed more of a danger than the sun!
This will bear watching.