America has a problem with drinking water pollution. It is not the pollution of old—massive amounts of industrial effluent pouring out of factories. It comes from far more sources, seeping into the water inconspicuously in small amounts, but adding up. And no one knows what its effects on us are.
The U.S. Environmental Protection Agency (EPA), which regulates drinking water, has identified 126 substances (and counting) that may be pervasive in U.S. drinking water supplies which it calls “contaminants of emerging concern” (CECs) or “emerging contaminants.”
The chemicals found in American drinking water include those used in industrial production, pharmaceutical ingredients, illicit drugs, and numerous substances of modern life with largely unknown health effects.
The EPA doesn’t know exactly how pervasive these contaminants are and it doesn’t know what human health impacts they have. For many of the substances, no safe level for human consumption has been set, because the effects haven’t been studied in depth.
The best broad sampling for CECs was done in 2001 by the U.S. Geological Survey (USGS). It tested for 124 contaminants in 25 groundwater and 49 surface-water sources across the country. It found at least one of the contaminants in 96 percent of the samples.
Right now, USGS is working with EPA to study tap water more extensively. Research hydrologist Dana Kolpin, chief of the USGS Toxic Program’s Contaminants of Emerging Concern Project, explained that most current studies are focused on assessing how much of these substances are in U.S. drinking water. Determining what effects they have on humans is still a few steps away.
We’ve seen that some definitely have impacts on wildlife, such as the fish that swim in our drinking water sources, but “we haven’t seen a smoking gun to say definitively that exposure to emerging contaminants in our drinking water … is causing a human health effect,” Kolpin said.
The USGS and EPA tapwater study drew its last samples earlier this month, and Kolpin said they might have a better idea in the next six months of how contaminated America’s tap water is.
Cynthia Lane, American Water Works Association’s director of engineering and technical services said, “The thing with emerging contaminants that we struggle with is really that’s present in any source, whether it’s a waste-water source, or a river source ... that’s ubiquitous through any source that we have.”
CECs often come from people’s homes.
For example, people take medications, and their bodies absorb part of the medication, but the rest passes into the toilet. The wastewater is treated, but CECs slip through—partly because wastewater treatment facilities haven’t been told to remove them and partly because different filtration techniques may be needed to do so. The wastewater containing CECs is then released into rivers or other bodies of water used as drinking water sources.
Airborne CECs may also settle into drinking water sources, or seep into them from other places.
They can permeate the environment surrounding landfills, and eventually enter some freshwater bodies this way. USGS studied the presence of emerging contaminants in landfill leachate and found the most frequently detected CECs were lidocaine (a local anesthetic, found in 91 percent of samples), cotinine (a nicotine breakdown product, 86 percent), carisoprodol (a muscle relaxant, 82 percent), bisphenol A (a component for plastics and thermal paper, 77 percent), carbamazepine (an anticonvulsant, 77 percent), and N,N-diethyltoluamide (DEET, insect repellent, 68 percent).
