A new study has discovered nearly 70 pharmaceutical drugs in Australia’s river creatures, a worrying sign that the pills we take are not properly filtered out of wastewater before it reaches the environment.

“When we take a pharmaceutical, all of the drug is not always used within our system, so we do excrete some, by urine typically, that does end up in wastewater treatment facilities,” lead author of a new paper published in Nature Communications, Dr Erinn Richmond, said in a statement. “Or if you’re connected to septic, it ends up in a septic tank. And with aging infrastructure, the tanks aren’t necessarily perfect; there’s some leakage, and we believe that’s a pathway of exposure into the streams.”

Richmond and her team from Monash University looked at aquatic creepy-crawlies in six creeks in Melbourne, Australia. They tested insect larvae for 98 different pharmaceuticals, the most extensive sample ever tested. To see whether the drugs were traveling up the food chain, they also tested spiders that eat the insects.

Of the 98 drugs they were looking out for, the team noted the presence of 69 in the insect larvae. The medicines most commonly found ranged from painkillers and blood pressure drugs to antidepressants and Parkinson’s medication.  

And the drugs had indeed made their way up the food chain, with 66 identified in the spiders. Therefore, the chemicals likely end up in many other creatures throughout the ecosystem.

Animals likely to be affected include birds, bats, frogs, fish, and duck-billed platypuses. The researchers estimate that critters like platypuses could be ingesting about half the daily human dose of certain drugs like antidepressants. It’s not clear exactly how these medications, particularly when interacting with a cocktail of other drugs, might be affecting these animals, but as Richmond pointed out to New Scientist, it’s probably not good.   

“Certainly if we ourselves went to a doctor and said we were on 69 different drugs, they would probably be quite concerned,” she said.

Another member of the same research group, Jake Martin, has previously investigated how mosquito fish react to the active ingredient in Prozac, a common anti-anxiety drug. The males became more sexually aggressive when exposed to the drug, meaning that the females suffered as they were harassed more frequently. What’s more, the fish became less wary of predators, threatening their ability to survive.

This is just a snapshot of how human medications affect wildlife. While the tests used are the best available, they still don’t have the ability to detect the majority of the drugs we use. Therefore, it’s likely that the reality is worse than the findings of this latest study.

It’s clear that we need better methods for treating water to remove these chemicals before they reach natural bodies of water. Some sewage treatment plants are currently testing out ways to do this.