"“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. “We have an aging demographic, and we have an increased reliance, in North America and Europe in particular, with the treatment of health concerns with pharmaceuticals.” This translates to more medicines making their way into the water system, and we need to determine how to deal with it, she says. “Long-term exposures [to pharmaceuticals] are quite a bit different than short term exposures, and we need to really start testing and figuring out if chronic exposures of low doses are relevant for the health of an individual or population of animals.”"