A new study revealss that most of the high concentrations of pharmaceuticals in wastewater don’t come from people flushing their meds willy-nilly down the toilet, as New Scientist reports. Rather, we are flushing meds through our bodies into the sewers. 

In a new study in Science of the Total Environment, scientists collected wastewater from the University of Vermont over 10 days while students were moving out at the end of the school year. The result didn’t show a massive spike in drug concentrations in the water, indicating that when students moved out, they weren’t dumping all their pills into the toilet.

The study did find that a large student population has a tangible effect on the local wastewater, though. As students left, the amount of caffeine and nicotine in the water decreased, but not significantly, while certain other meds showed an increase. As it turned out, student pee was actually diluting the wastewater of the older, permanent population in the area. After the students (and their pee supply) left, the water had higher concentrations of antidepressants, diabetes drugs, and ulcer medications. 

This research is about more than just student smoking habits. Birth control hormones in the water supply have been found to negatively affect wildlife, creating intersex fish and frogs. Treatment plants don’t remove all of these chemicals, and some end up back in our water supply in addition to polluting natural bodies of water. 

Despite the wastewater issue, the FDA actually recommends some medications be disposed by flushing to prevent them from being taken by children, pets, or anyone else—mainly powerful painkillers like oxycontin and percocet. Less dangerous meds can simply be trashed. While both can be turned over at DEA drug take-back events, the government is well aware that many people won’t wait around until their next safe disposal event.

Since the pharmaceuticals in our water supply and sewage don’t have much to do with human behavior that could be changed—unless you want everyone to go off their birth control or just stop peeing for the sake of the fish—the growing body of research on the topic shows an immediate need for better wastewater treatment.

[h/t New Scientist]

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