Editor's note: This article is a reprint. It was originally published on January 10, 2017.
According to an edited survey by the National Center for Health Statistics, 48.6% of Americans used at least one prescription drug in the past 30 days. Nearly 24% used three or more during that time, and more than 12.8% used five or more.1
While taking large doses of medications, especially when unnecessary or inappropriately prescribed, can have negative effects on an individual’s health, another often overlooked consequence is the impact they have on our world’s waterways in the form of drug contamination.
When you take a drug, only a small portion of it is metabolized by your body. The rest is excreted in your urine or feces and ends up in wastewater (most water treatment plants are not equipped to remove drugs from the water supply).
Topical medications (creams or lotions) can also be problematic if the unabsorbed portion flows down the drain. There is also the problem of unused medications flowing down the toilet or drain (both in private homes and in healthcare facilities such as nursing homes).
Even during the manufacturing process for pharmaceuticals, levels of drug contamination can increase downstream from the factory (up to 1,000 times higher in some factories, according to a Harvard Health report).2
When these unnatural chemicals enter our waterways, they not only pose a risk to human drinking water supplies, they also harm marine life in surprising and shocking ways.
Loss of inhibition in juvenile salmon due to anti-anxiety medication
You might be surprised to learn that salmon get stressed, but it’s quite normal. Young salmon need to leave their freshwater nests and go to the ocean. This is a necessary migration, but if done too early or without proper care, it can be fatal.
According to Gustav Hellström, a salmon biologist at Umeå University in Sweden, stress in salmon is likely an adaptive response that helps them minimize unnecessary risk taking and remain alert.3
A study by Hellström and colleagues found that exposure to anxiolytics changed the behavior of salmon, causing them to move almost twice as fast as unexposed salmon.4
The salmon were given low doses of oxazepam, the most commonly prescribed anti-anxiety drug in Sweden.5), similar to the concentrations found in the effluent. According to the study:6
“Exposure to oxazepam is known to reduce anxiety in fish… and increase risk taking… Therefore, the enhanced locomotion seen in our study could be explained by a decrease in anxiety that could limit the intensity of risky activities such as locomotion.
Downstream migration behavior is critical to the salmon life cycle, and the timing and intensity of migration are adaptive as they affect fish survival and health. Any disruption to salmon migration behavior can have unforeseen and serious ecological consequences.”
Meanwhile, use of anti-anxiety medications is increasing worldwide, and some estimates suggest that levels of oxazepam in water near urban areas could more than double in the coming decades.7
Studies have shown that oxazepam persists in therapeutic form for decades after it has settled in freshwater lakes, and that past inflows and increased use have led to increased concentrations in lakes, but the consequences are entirely unknown.8
Psychiatric drugs alter the behavior of wild European bass
Studies around the world have shown the effects of pharmaceutical contamination even at diluted concentrations. In one study on European sea bass, diluted concentrations of oxazepam in water changed the behavior of the fish, causing increased activity, decreased sociability, and increased feeding rates.9
The fish stopped schooling, a type of behavior that fish use to gather together to avoid predators. The fish also took more risks, going out to explore on their own more often.
Concerns about oxazepam concentrations have previously been detected in the Pyris River, which flows through Uppsala, Sweden. “In sea bass caught in the Pyris River, the research team found oxazepam concentrations in muscle tissue that were up to six times higher than in the water,” Science magazine reported.10
The researchers also noted that similar effects are likely to occur in other fish exposed to the drug, because oxazepam binds to GABA receptors, a cell signaling mechanism found in many species.11
Antidepressants and Diabetes Drugs Found in Puget Sound Fish
Puget Sound, off the northwest coast of Washington state, is another body of water polluted by wastewater treatment plant runoff.
A study conducted by the National Oceanic and Atmospheric Administration's (NOAA) Fisheries Service's Northwest Fisheries Science Center found 81 chemicals in the water, including the antidepressant Prozac and the diabetes medication Metformin.12,13
The researchers then examined native fish living in the Sound—juvenile Chinook and Pacific salmon—and detected 42 chemicals in their tissues, some of which were present at levels high enough to affect growth, reproduction, and/or behavior.
It is not known whether eating fish contaminated with these drugs poses a risk to humans, but NOAA Fish Research Scientist and lead study author Dr. James Meador noted that there may be additional risks because the fish are exposed to a complex cocktail of chemicals.14
“There is also the problem that we don't know how these chemicals will behave in fish when found together in mixtures… These mixtures may result in reactions that occur at lower concentrations than the individual compounds.”
A separate study found that exposure to the drug metformin was linked to the development of intersex fish, a condition in which male fish show evidence of feminization.15
Previously, hormone-mimicking drugs, such as birth control pills, were blamed for the hermaphroditic fish found in the Susquehanna, Delaware and Ohio River basins in Pennsylvania.16 Metformin is not a hormone mimicking drug.
However, researchers believe it may be an “unconventional endocrine disruptor,” and is thought to be one of the most common pharmaceuticals found in wastewater (not only because it is so commonly used, but also because it is extracted from the body unchanged and not metabolized).17
Prozac Makes Fighting Fish More Gentle
Antidepressants are another group of drugs that are all too common in water supplies. Researchers at the University of New England in Maine tested the antidepressant Prozac on fighting fish using two concentrations, one similar to that found in waterways and one higher.18
After exposure to the drug, the fish became less bold. They were less likely to explore their surroundings, stayed in one place more, and were more hesitant to approach other fish. They also showed more erratic behavior, and the behavioral effects increased with drug dose.
Prozac exposure caused behavioral changes one day and one week after exposure. Even after the fish were allowed to swim in clean water for a week, the behavioral effects of Prozac exposure were still present in the fish. If these changes occurred in the wild, they could have significant implications for the fish’s chances of survival.
How many drugs are in fish dishes?
A report by the UK-based environmental charity CHEM Trust further highlighted the problem of pharmaceutical contamination contaminating marine life.19
They found that 613 pharmaceuticals were found in environments worldwide, but this is likely a gross underestimate, as there are no analytical detection methods for most drugs currently in use.
Despite this, rivers around the world have been found to be contaminated with pharmaceutical pollution. The report also found:20
- 23 drugs detected in Swedish sea bass, including antidepressants, tranquilizers, antibiotics, painkillers and anticancer drugs
- Ethinylestradiol, a drug used in birth control pills, detected in Baltic salmon
- Although some drugs have been shown to be harmful to animals at levels found in the environment, little wildlife monitoring for such effects has been done.
Gwynne Lyons, CHEM Trust policy director and report author, said:21
“Most people would be surprised to learn that they excrete between 30% and 90% of the medications they take. With so many drugs now being found in our rivers, action is needed on all fronts to protect our wildlife and drinking water.
The long-term effects of many highly potent drugs in our environment can be devastating. The current situation is mind-boggling, with fish contaminated with birth control pills, antidepressants (e.g. Prozac), tranquilizers, antibiotics, painkillers, anticancer drugs, and god knows what else.”
Reducing the pharmaceutical footprint
One of the most basic ways to reduce drug contamination at the individual level is to use medications only when absolutely necessary. Taking care of your health can help a lot in this regard. When taking medications, do not flush unused medications down the toilet or pour them into the drain.
Instead, many areas offer drug take-back programs where you can dispose of your medications at a designated location in your area (sometimes at your local law enforcement agency or pharmacy). If these programs are not available in your area, you can dispose of your medications in the trash.
It is recommended that you take the tablets out of the package, crush them and seal them in a plastic bag with water and sawdust, cat litter or coffee grounds (this is to prevent animals or children from eating the contents).22
On a larger scale, environmental groups have called on drug companies to produce “green” drugs that are easily broken down in the environment when released. There is also an urgent need to stop unnecessary use of drugs in food animals.
Which fish are safe to eat?
Although it is not known what effect consuming seafood contaminated with pharmaceuticals has on human health, it is always wise to seek out pure and uncontaminated food sources. Unfortunately, most seafood no longer falls into this category.
The safest and healthiest omega-3 fats in terms of contamination are wild-caught Alaskan salmon and sockeye salmon. Neither is allowed to be farmed, so they are always caught in the wild. The risk of sockeye accumulating large amounts of toxins is reduced by its short life cycle of about three years.
Also, bioaccumulation of toxins is reduced because you are not eating other fish that are already contaminated. Two names to look for on labels are “Alaskan salmon” (or wild Alaskan salmon) and “sockeye salmon.”
Canned salmon labeled “Alaska salmon” is also a good choice and provides a cheaper alternative to salmon fillets. The general rule of thumb is that the closer a fish is to the bottom of the food chain, the less contaminated it is. So other safe choices include smaller fish such as sardines, anchovies, and herring.
No matter what type of fish you’re considering, look for varieties that are Marine Stewardship Council (MSC) certified. This certification ensures that every component of the manufacturing process, from how the raw materials are harvested to how the product is made, has been scrutinized by the MSC and independently audited to ensure they meet sustainable standards.
Finally, before adding wild fish to your diet, there is one thing to be careful about: portion control. While it may be tempting to eat a lot of fatty fish to increase your omega-3 intake, this can actually be a recipe for disaster, as omega-3s are also polyunsaturated fatty acids (PUFAs). Consuming too much can cause metabolic damage when PUFAs are broken down into advanced lipid oxidation end products (ALEs).
