Plastic pollution in our oceans, lakes, and rivers has gained vast media attention over recent months, and rightly so: approximately 8.8 million tons of plastic are released into the oceans each year.

fate flush pharmaceuticals seas blog illinois science council

Peanut the red-eared slider turtle has become a victim of plastic pollution. (c) Missouri Department of Conservation. Read more about him here.

We have all seen the terrible images of turtles with straws stuck up their noses or plastic beer can holders wrapped around their bodies (right) Its images like these that make it easy to understand why the public is demanding immediate action against plastic pollution.

But it’s not just plastic that is beginning to drastically impact on our seas. A less visual yet just as concerning threat is upon us: pharmaceuticals. 41% of the world’s population lives along the coastline, and the scientific community is starting to become concerned about peoples’ release of pharmaceuticals into their waterways. Like plastic, pharmaceutical pollution is a man-made problem caused by individuals and businesses who do not dispose of their pharmaceuticals properly. Many people flush their pharmaceuticals down the toilet, where they reach sewage treatments plants, stay intact, and escape into our rivers and eventually seas. Furthermore, many of the drugs we take daily, such as birth control and antidepressants, aren’t fully broken down inside our bodies, and they get flushed, too, in our urine. But pharmaceutical pollution doesn’t just happen in our bathrooms. Medicines that people thrown away end up at landfills, where they can leach through the soil and enter our rivers directly.

Even the smallest amount of medicinal waste can greatly damage marine life. Its effects can be seen at concentrations as low as one nanogram per liter (the equivalent of 10 grains of sugar in an Olympic sized swimming pool!). Professor Alex Ford at the University of Portsmouth found that 10-100ng/L of Fluoxetine (more commonly known as the antidepressant ‘Prozac’) can significantly affect the swimming habits of a tiny crustacean called an amphipod. Alex and his colleagues found that seretonin controls whether the organism prefers swimming to light or dark places, and by subjecting these creatures to tiny amounts of this antidepressant, which increases serotonin levels in the brain, the amphipods were five times more likely to move towards the light.

fate flush pharmaceuticals seas illinois science council blog

The amphipod Echinogammarus marinus, which is commonly used in ecotoxicology lab experiments. (c) Malcolm Storey at

Why does this matter? Well, in the wild, if these organisms are more attracted to well-lit open water, they are more likely to be eaten by predators. If this happens, their population numbers might tumble. Most of these studies, however, have only been carried out in the laboratory, and so, it is important that scientists begin to measure the effects of these pharmaceuticals in the wild directly. This way, we can gain a better understanding of the impact of pharmaceuticals on the overall food chain.

Other scientists have found that pharmaceuticals in their water can reduce a young cuttlefish’s ability to camouflage itself and increase its tendency to dig in the sand, which makes it more visible to predators, just like the Amphipods.

One of the most shocking effects of pharmaceuticals in the ocean has nothing to do with serotonin. Rather, the hormones found in birth control pills have given rise to transgender or ‘intersex’ organisms. Intersexuality is a scenario when an animal displays both male and female characteristics simultaneously, either externally or internally, within the reproductive organs.

Professor Charles Tyler at the University of Exeter showed that, across fifty test sites, twenty percent of male freshwater fish, such as the common roach, displayed feminine characteristics. This may not sound like a big deal, but in reality, it can make it more difficult for this species to find mating partners and can lead it to extinction. Furthermore, Swedish scientists found that fish have more estrogen receptors than humans, and consequently, they are more vulnerable to estrogen in the water. They found that estrogen was causing a change in the fish’s genetic balance and that individual fish who’ve been subjected to estradiol are having a harder time capturing food.

It is plain to see that the effects of pharmaceuticals in our seas and rivers are widespread and are producing varying side effects. The EPA does not regulate many of these low-concentration contaminants, which is why further research into their effects on marine life is vital.

We can begin to play our part by disposing of pharmaceuticals responsibly. If you have any medicines that you don’t need any more, please return them to your doctor or local drug store, as they will be able to dispose of them safely. We don’t want to make so much progress with plastic, only to have it be replaced by another, equally significant tragedy.


  • Ellis Moloney

    Ellis Moloney is a master's student in applied aquatic biology at the University of Portsmouth in the United Kingdom. Ellis writes his own blog, The Science Rationale (, and you can find him on Twitter @Ellis_Moloney.

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Total Solar Eclipse on April 8, 2024

Total Solar Eclipse on April 8, 2024

On April 8th, 2024, a total solar eclipse will sweep across North America, from Mexico to the Maine-Canadian border. For those who experienced the spectacular solar eclipse of 2017, this one will be similar, crossing the United States from west to east and passing through or near several major metropolitan areas. And while its path is quite different this time, Carbondale, Illinois, a reasonable destination for Chicago-area residents, will once again be on the line of totality.    

Just a little background on eclipses:  Lunar and solar eclipses are not uncommon – they each occur about twice a year when the moon is crossing the ecliptic, the path of the sun in the sky.

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