Let's face it: In the western world, people expect their drinking water to be safe, which is why the 2016 lead-contamination water crisis in Flint, Michigan, elicited such widespread public and political outrage. (And rightly so.) But often overlooked is the reality that in addition to the possible presence of toxic metals, there are likely pharmaceuticals in our water supply. In fact, 47 different pharmaceutical drugs were detected in source water samples that feed into drinking water treatment plants, and 37 different drugs were found in the water after it was treated at 25 drinking water treatment plants across the US, according to a February report.
On National Prescription Drug Take-Back Day, the Drug Enforcement Administration encourages all pharmaceutical users to check the National Take-Back Initiative website for instructions on how to return your pills rather than let them get into our water supply. (At other times of the year, you may be able to find a community pharmacy in your area that disposes of medications through Dispose My Meds.) Thing is, while many people are guilty of flushing their pills down the toilet, most drugs get into the water via excretions from our bodies.
"Your body doesn't look at pharmaceuticals as something you're taking to help you; it looks at them as foreign chemicals and many of them are not completely degraded in the body," explains Edward Furlong, a research chemist with the US Geological Survey in Denver who has conducted extensive research on this issue. What's more, prescription drugs can enter our waterways and drinking water supplies through manufacturing waste, animal excretion, runoff from animal feeding operations, or leaching from municipal landfills, according to a 2010 report from the Natural Resources Defense Council (NRDC).
Here's the real shocker: The presence of pharmaceuticals is not regulated in our drinking water supply. "People may find it hard to believe, but this country still doesn't require our drinking water systems to remove prescription drugs and many other contaminants from our tap water," says Erik Olson, director of NRDC's Health program. "In the same way that many of our roads and bridges are falling apart, our drinking water systems are aging, and most use outdated treatment technologies that don't remove a wide variety of today's contaminants, ranging from pharmaceuticals to many industrial chemicals and pesticides. We're not optimistic that the new EPA [under the current administration] will do much about this."
These pharmaceutical agents include analgesic, antibiotic, anticoagulant, antidepressant, antihistamine, and antihypertensive drugs, hormones (from oral contraceptives and hormone-therapy), and muscle relaxants, among others. Lithium (used to treat bipolar disorder), carbamazepine (an analgesic/anticonvulsant), metoprolol (an antihypertensive), and buproprion (an antidepressant) were the most frequently detected drugs in the water samples after treatment.
Because these drugs are present in trace amounts in the drinking water supply, there isn't an imminent danger to human health. But experts are concerned about the long-term effects from repeated exposure because "they have the potential to bio- accumulate and be toxic to humans," according to a scientific review by researchers at Anglia Ruskin University in Cambridge, UK. A bigger concern is the possibility that some of the drugs that are in drinking water could interact with medications people are taking intentionally, says Ted Schettler, science director of the Science & Environmental Health Network. Theoretically, this could compromise the effectiveness of the prescribed drug or lead to adverse symptoms stemming from the interaction—but this hasn't been well studied.
There's also a concern about antibiotic residues in the water supply: Because antibiotic traces end up in the water or sludge that's being put onto the soil where crops are grown, resistant bacteria can develop, Schettler notes, and this could contribute to the growing problem of antibiotic resistance. "I don't think any of us know how big a deal this is," Schettler says.
Certain types of filtration systems are better at removing pharmaceuticals than others are. Many wastewater treatment plants use filtration systems that involve activated sludge: At the plant, water is mixed with microbially active solids that break down the pharmaceutical chemicals, Furlong explains. "But if our bodies don't completely break down a particular pharmaceutical drug, it may not be broken down well by the activated sludge, either," which means it can linger in the treated water supply. A better system is activated carbon treatment, which improves the removal of pharmaceuticals from the water supply, but this isn't widely used, Furlong says.
Drinking bottled water isn't necessarily the solution, because depending on how it is sourced and treated, bottled water may contain these pharmaceuticals, too. After all, "a lot of bottled water comes out of a tap somewhere," Schettler says. "If it's treated with reverse osmosis, it's likely to be cleaner."
At home, if the filter on your tap or fridge contains active carbon, it may help remove some of these drugs from your tap water. An even better system is the combination of reverse osmosis and carbon-based filtration, which removes more contaminants from tap water.
To prevent this problem from getting worse, it's crucial to get in the habit of disposing of unused medications properly, experts say. Don't flush them down the toilet; instead, mix them with coffee grounds, put them in a sealed plastic bag, and place it in the trash. Or participate in today's Take Back program.
UPDATE 4/18/17: A previous version of this piece stated that drinking water treatment plants use filtration systems that involve activated sludge. It's since been corrected to say that wastewater treatment plants do so.