Wastewater treatment plants remove lots of harmful materials, but scientists have been finding trace amounts of pharmaceutical and illicit drugs in our drinking water that most common filtration systems don’t catch. These drugs wind up in the sewage system, both through human excretion and through people flushing unwanted drugs down the toilet. The drugs that have been detected include painkillers, birth control, anti-depressants, and antibiotics.

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Fish on Drugs

The issue first reached mainstream concern when researchers in the United States discovered male small-mouth bass with eggs in their testes. These intersex fish have been attributed to irregular estrogen levels in the river water from pharmaceuticals like birth control. Other studies have found that some minnows exposed to antidepressants experienced developmental delays, anti-social behavior and less interest in mating.

The more research that’s done, the more possibilities for complications arise. Some studies have found evidence of antibiotic resistance in the aquatic environment due to antibiotic exposure. Whether this will have a significant impact on the environment, or if it may contribute to human antibiotic resistance, is still inconclusive.

Other studies have found that some minnows exposed to antidepressants experienced developmental delays, anti-social behavior, and less interest in mating.

Dr. Chris Metcalfe, a professor at Trent University’s School of the Environment, has been researching the toxic effects of drugs and other contaminants in aquatic environments since the early 2000s. In his studies, he has found that antidepressants accumulate more within fish than other pharmaceuticals, and this may influence the behavior and mating habits of different fish. Metcalfe has also begun investigating the impacts of illicit drugs on aquatic organisms, an area of study where he says there isn’t as much research being done.

“We have been doing some work on the effects of antidepressants and illicit drugs on neurotransmitters in the brain. [These drugs] actually modulate neurotransmitters, things like dopamine and serotonin,” explains Metcalfe. “What this means to the actual fish is difficult to sort out at this point. What we do know is those levels in the brain are important as signals for spawning.”

What About Humans?

While there has been research on the impact of pharmaceuticals on aquatic ecosystems, little research has been done into the potential effect on humans. This lack of research is largely because detection levels were so low, most scientists believed they weren’t harmful. Still, there are some who believe chronic exposure could negatively impact humans and fear governments won’t act until it’s too late. Countries now face the decision whether to take preventative or responsive action.

Part of the reason few countries have installed new treatment plants is because funding these updates would be extremely costly. According to Metcalfe, the best way to reduce drug levels in drinking water is to employ tertiary treatment: a more thorough, three-step process of treating wastewater. Most treatment plants are only capable of secondary treatment.

Some tertiary plants have been popping up in North America, and especially in Europe. Still, many governments aren’t interested in investing millions of dollars to filter out pharmaceuticals that so far, show no adverse effects to humans – even if there is evidence these contaminants disrupt river ecosystems.

“The use of pharmaceuticals in Canada is increasing by ten to twelve percent every year. It doesn’t take a mathematical genius to figure out that in a decade, you’ve got over a hundred percent increase in drug use.” –Dr. Chris Metcalfe

In Canada, for example, the Sechelt Water Resource Centre in British Columbia was planning to experiment with technology called biochar, a charcoal filtration system believed to efficiently remove pharmaceuticals. The experiment wound up not being approved because Sechelt’s council felt it couldn’t justify investing tax payer dollars for an uncertain experiment on what is dominantly perceived as a low-risk issue. While the Sechelt centre is capable of tertiary treatment, the plant has drawn controversy for being much more expensive than was anticipated.

As for humans consuming affected fish, there hasn’t been much research into this either. Metcalfe emphasizes the trace amounts of drugs in fish tissue are extremely low and “probably negligible,” but little risk assessment on human consumption has been done.

While these contaminants are in extremely low concentrations, researchers are still analyzing for trends and finding that aquatic life has been affected.

“The use of pharmaceuticals in Canada is increasing by ten to twelve percent every year,” Metcalfe explains. “It doesn’t take a mathematical genius to figure out that in a decade, you’ve got over a hundred percent increase in drug use. Certainly, that indicates this is a problem that’s not going away any time soon.”

Indeed, a recent U.N. report indicated the United States and Canada currently lead the world in the highest per-capita opioid use.

Regular analysis can also offer valuable information on human activity. For example, Metcalfe recalls when the opioid OxyContin was banned in Ontario in 2012, and “almost immediately we started seeing fentanyl in the waste water and surface water.” He cites a lack of funding as the reason they haven’t gone back to check opioid levels since then, but explains “you can calculate from the wastewater what the use is in the community.”

Once again, Metcalfe points out these levels are extremely low, explaining “you would have to consume the water for probably your entire life to get the kind of dose you would get in a week of actually taking the drug.” However, he accepts “risk perception is important. As scientists, we tend to think in black and white, risk or no risk. But the public has a different perception, and the idea of contamination of their drinking water is not acceptable.”

Keeping Drugs Out of Your Water: Prevention

Besides living in areas with upgraded wastewater treatment plants, there are a few other initiatives individuals can take to decrease the amount of drugs in drinking water. If you are concerned about your own water source, consider having your water tested by an independent water testing service. Purchasing a water filter that can lessen your exposure to pharmaceuticals is another proactive step. Big Berkey Water Filters state that their black water filters will “filter out some, but not all pharmaceuticals.”

It’s also important to take advantage of local drug take-back programs to properly dispose of expired or unwanted pharmaceuticals and personal care products. Across Canada, pharmacies participate in this kind of drug-return program. The issue is more complicated with discarding illicit drugs, since a few city police departments accept illicit drugs without charging for possession.

However, there are still disagreements on how to throw away drugs across different countries. Health Canada advises Canadians not to flush any drugs down the toilet, encouraging people to return them to a pharmacy. Alternatively, the Food and Drug Administration in the United States recommends flushing certain drugs down the toilet, such as those that include fentanyl, morphine and oxycodone.

“We appear to have a kind of dichotomy of opinion,” says Metcalfe. “[The FDA] feels that getting rid of these drugs and not letting them fall into the wrong hands is preferable over concerns about potential environmental implications, whereas Health Canada has a more nuanced view that if these drugs can be taken back to the pharmacies to be safely disposed of, that’s the way to go.”
Metcalfe concurs with Health Canada’s recommendation.

The one thing everyone seems to agree on is that it will be very difficult to bring down the number of drugs people are ingesting today, both due to a pharmaceutical culture and an aging population that requires more and more medication.

“It’s difficult, because we know pharmaceuticals have a benefit for people,” acknowledges Metcalfe. “They make people feel better, they protect us against health effects – so balancing that need against impacts to the aquatic environment are difficult to reconcile.”

Unless more local governments fund tertiary plants or people begin returning their pharmaceuticals on a large scale, the level of drugs in our water is unlikely to go down any time soon. For now, individuals and law-makers may want to pay attention to research by environmental experts, so everyone can better understand how our drugs are influencing not only our own bodies, but also the aquatic environment around us.

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