Protects against skin cancer, though. #tradeoffs?

New research shows hazardous chemical compounds can form as a result of the breakdown of avobenzone, a component of many sunscreen products, when it interacts with chlorinated water and UV rays. Something to keep in mind the next time you are poolside.

Avobenzone is the most popular UV filter in the world and has been approved by the US Food and Drug Administration since 1988. The ability of avobenzone to absorb ultraviolet light in a wide range of wave lengths means it is an ingredient in lipsticks, creams and other cosmetics, as well as sunscreens. Avobenzone itself is safe, but chemists from the Lomonosov Moscow State University used chromato-mass spectrometry to determine that when avobenzone mixes with chlorinated water (like that found in most swimming pools) and sunlight it can form various organic compounds, some of which belong to the toxic chemical class of phenols and acetyl benzenes.

“On the basis of the experiments, one could make a conclusion that a generally safe compound transforms in the water and forms more dangerous products,” said Albert Lebedev, PhD, and one of the study’s lead authors. “In spite of the fact that there are no precise toxicological profiles for the most established products, it’s known that acetyl benzenes and phenols, especially chorinated ones, are quite toxic.”

At the same time, sunscreen has been proven to prevent skin cancer, so the decision not to slather up this summer isn’t so clear cut. Perhaps the safest course is to use sunscreen whenever there’s no chance the kids will jump in a pool. And when you are poolside, ditch the waterproof sunscreen and simply limit kids’ time in the water so they don’t burn.

The scientists are now studying the transformation of avobenzone under conditions of chlorination and bromination of fresh and sea water to see if the number of chemicals avobenzone breaks down into is even more varied.

The study was published in the journal, Chemosphere.