Just about a month ago, I wrote about sharks in the Caribbean turning up with human substances in their systems, cocaine included. Now it turns out scientists aren’t just observing the problem anymore. They’re recreating it on purpose.

In 2022, researchers from the Swedish University of Agricultural Sciences, led by environmental toxicologist Jack Brand, implanted young Atlantic salmon with slow-release doses of cocaine and its primary metabolite, benzoylecgonine. The goal was to measure how real-world drug pollution is altering ocean animals.

In the study, the dosed salmon swam faster and traveled farther than their sober fishy brethren. Fish exposed to benzoylecgonine were the most altered, eventually covering up to 90 percent more distance and swimming significantly farther into Sweden’s Lake Vättern. Cocaine itself had similar, if slightly less dramatic, effects.

The fish didn’t die faster, which sounds alright on the surface, but it’s ultimately not a metric that matters much in this case. Behavior is.

Scientists Put Cocaine in Salmon to See What Our Waste Is Doing to Nature

Evolution has specifically fine-tuned fish to survive and thrive in their very specific environment. If you change how they move, even a little bit, you change everything about them. What they eat, how they eat, what eats them, and how populations of fish disperse themselves among their natural habitats.

Increased activity because it’s on a cocaine bender might mean it uses more energy, which, when it crashes, exposes it to predators. When it suddenly gets a burst of cocaine rage that it uses to swim deeper out into the lake than it’s ever been before, it’s occupying a new ecosystem that it can potentially disrupt.

All this has the team of researchers worried that all of the stimulants we are pumping into our oceans via urine might be “invisible agents of global change,” Dr. Brand told the New York Times.

Human waste is the problem here, and it doesn’t get neatly deposited into a toilet and then quarantined from the rest of society as it’s whisked away to a waste treatment plant to be rendered inert. Wastewater systems process tens of billions of gallons of wastewater daily, and most aren’t equipped to filter out complex chemicals, including pharmaceuticals and illicit drugs. Studies have already found everything from antidepressants to painkillers in wild salmon. Cocaine is just the funny, attention-grabbing headline.

Human mood stabilizers and destabilizers are pouring into ecosystems in measurable amounts, and their effects are becoming evident in lab tests. We’re only just beginning to see what effects the chemicals we pee out will have on nature.