“High” Tide: Aquatic organisms may be in for a bad trip

By Celeste Barnes-Crouse

Source: Wikimedia Commons

Did you know that the pharmaceuticals you take can end up in your pee? And once that’s flushed down the toilet, they can build up in aquatic environments. At the 2018 Ocean Sciences Meeting, researchers Tawnya Peterson, Brittany Cummings and Joseph Needoba discussed how freshwater and coastal marine environments near urban centers can retain dissolved drugs, and how this has the potential to biologically affect the organisms in these ecosystems.

Medications enter freshwater and marine ecosystems as chemical constituents of our urine following our doses, or directly flushed down municipal toilets (yes, the FDA recommends flushing certain medications down your toilet to dispose of them). Our wastewater treatment systems aren’t designed to filter these out before releasing the water into the environment. Fluoxetine antidepressants (such as Prozac), ibuprofen painkillers (such as Advil), and metformin to treat Type II diabetes (such as Glucophage) are among the compounds that scientists are paying attention to. There is evidence suggesting that the concentrations of these medications could harm organisms, including some crab, fish and shellfish species.

Source: Rzymski, Drewek & Klimaszyk (2017)

One study showed that fluoxetine can alter the normal behaviors of shore crabs. Rather than staying hidden, the shore crabs became more active during the day and more aggressive in the presence of their predators. They got into more conflicts, which caused them to lose limbs in fights or die. In the wild, their predators would be more successful because the crabs’ natural fear and defensive strategies were subdued.

The findings from another study suggested that metformin may be an endocrine disruptor in fish, causing reduced reproductive success. In fathead minnows, cases of intersex fish increased when exposed to metformin (where male reproductive tissues have characteristics of feminization). Smaller male fish were also reported, with lower fecundity in mated pairs. If smaller fish pass along their genes in reproduction, eventually the average body size of fish in the population could suffer. If females are affected, their smaller body size means they can carry fewer eggs or eggs of smaller size, which are less likely to survive.

Mussels, oysters, and other shellfish are at risk of contamination from pharmaceuticals in the water due to their filter-feeding strategies. Fluoxetine and antibiotics may accumulate in the mussels’ body tissues and affect feeding, reproduction, and reduce their growth. In a series of study sites from the southern Oregon coast to central Washington coast, antibiotics and antifungals were found in Pacific oysters. This risk of bioaccumulation is important to monitor because these pharmaceutical contaminants could cycle back to us when we eat these species.

Source: Rosalyn Davis

Though it may seem like tides, currents or waves may dilute these contaminants quickly, due to varying conditions in freshwater areas and along the coast this is not always the case. It’s important that we challenge these assumptions in order to improve how we interact with and steward our environments properly. While there’s not much we can do about the way our bodies process medications into our pee, we do have options when it comes to disposing of leftover medications. Call and ask if you can return any leftover or unwanted pharmaceuticals to your doctor or pharmacist, or find a drop box where you can leave them (for example, here is a list of drop box locations in Seattle, or where to find them in King County). Don’t rush to flush! Our fishy friends will thank you.