RODALE NEWS, EMMAUS, PA—As important as it is to protect our skin from the sun, this summer it's also becoming clear that some sunscreens may have negative effects of their own. Last week, Senator Chuck Schumer (D–N.Y.) called attention to the fact that the Food and Drug Administration isn't releasing evidence showing that the some sunscreen ingredients could be promoting skin cancer. Now, a new study published in the journal Chemical Research in Toxicology raises concerns that ingesting sunscreen nanoparticles—chemicals rendered into tiny particles so the sunscreen won't turning your skin a ghostly white—could be damaging to cells inside your body. But there's no need to forgo sunscreens out of safety concerns. First, don some stylish sun-protection clothing, which is the safest and most effective form of sunscreen, and then shop for safer sunblock.
THE DETAILS: The authors of this new study were trying to demonstrate what might happen if someone were to ingest nanoparticles orally, either in an occupational setting or by licking sunscreen off their lips or face. So they exposed mammal colon cells to various-sized particles of zinc oxide, a mineral used in sunscreens that physically blocks UV rays from skin rather than absorbing them and converting them to heat, as chemical sunscreen ingredients do. They found that nano-sized zinc oxide particles were twice as toxic to the cells as larger particles.
WHAT IT MEANS: If you were to ingest zinc oxide nanoparticles orally, there's a chance that they could cause damage to your colon and intestinal walls. "There have been some concerns about different nanomaterials, and zinc happens to be one that can be quite toxic if it comes into contact with cells," says the study's lead author Philip Moos, assistant professor in pharmacology and toxicology at the University of Utah. But exactly how much damage isn't really clear. On the one hand, he says, your stomach acid can break zinc oxide down into zinc particles, and your stomach and intestines have mechanisms that prevent the absorption of metals like zinc into the body. On the other hand, if you ingest large quantities, the zinc particles you consume may combine with the zinc already in your system, he says, and it might overload your body's ability to get rid of it.