This is a chemical that can kill bacteria. Companies have put it into toothpastes, soaps, hand sanitizers and other products to increase their germ-busting power. But triclosan washes down drains and into waterways. There, it can kill off good germs. Triclosan can also promote the development of bacteria that are resistant to triclosan and other germ-killers, including lifesaving antibiotics. That’s why, in 2016, the U.S. Food and Drug Administration banned triclosan — and some similar chemicals — from use in soaps. Soap alone should be enough to beat back the bad bacteria.
In a sentence
When triclosan ends up in streams, it can harm tiny water fleas that feed fish and other aquatic critters.