Author: Elizabeth Anne Brown

Some of the sunscreen you slather on this summer will end up in lakes, streams or the ocean, even if you don’t go swimming. And a growing body of evidence suggests that ultraviolet filters, the active ingredients in sunscreens, can harm creatures that live in the water.Some products are marketed as “reef safe” or friendly to aquatic life. But has that been proved? We talked to a dermatologist, several ecologists and toxicologists, and a chemical engineer to find out the best way to protect your skin and the environment, too.Your sunscreen optionsThere are two kinds of UV filters in sunscreens on the market today.Mineral sunscreens create a physical barrier on your skin that reflects UV rays like a mirror, while chemical sunscreens are absorbed into the skin and convert the UV radiation into harmless heat. (Chemical sunscreens are also sometimes labeled “organic,” but that’s a chemistry term, not a claim of environmental friendliness.)Any sunscreen you apply will eventually end up in water. Researchers estimate that between 25 and 50 percent of sunscreen comes off during a dip. The rest goes down the drain when you shower or enters the wastewater system through the laundry when you wash your beach towels.Most standard treatment plants aren’t effective at removing trace levels of UV filters from wastewater, said Dunia Santiago, a chemical engineer at the University of Las Palmas de Gran Canaria in Spain who studies how treatment plants process contaminants. That means the chemicals are still in the water that flows out of the plant and into the world.And, since many UV filters don’t biodegrade well, levels can build up over time in the environment, floating around, settling into sediment and being eaten by animals, especially in shallow areas popular with swimmers.We are having trouble retrieving the article content.Please enable JavaScript in your browser settings.Thank you for your patience while we verify access. If you are in Reader mode please exit and log into your Times account, or subscribe for all of The Times.Thank you for your patience while we verify access.Already a subscriber? Log in.Want all of The Times? Subscribe.