"“There’s been a fair amount of work done in both the U.S. and Canada as well as Europe that documents [pharmaceuticals] in wastewater and in water,” says Joanna Wilson, a biologist at McMaster University in Ontario, Canada. She studies how drugs in the water affect zebrafish, a tiny freshwater fish in the minnow family. More recent data shows that the same types of compounds are in drinking water. One study found several pharmaceuticals in treated tap water, including atenolol (a beta-blocker), carbamazepine (an anticonvulsant), gemfibrozil (an antilipidemic), meprobamate (an antianxiety medication), and phenytoin (an anticonvulsant). The concentrations of these compounds were very low, usually less than 10 nanograms per liter, which is parts per trillion. For reference, one part per trillion is equivalent to about one second in 64 years."