Are the nation’s streams tainted with hard drugs? If they're near urban areas, the answer is likely yes based on a new study that found amphetamine polluting water sources in Baltimore, CNN reports.

Researchers who tested samples from six streams around the Maryland city found them tainted with "amphetamine concentrations are high enough to alter the base of the aquatic food web," per a press release.

The drugs got there after they were flushed down the toilet by users either purposefully or, er, naturally. Limited filtering systems at wastewater treatment plants or "leaks in the sewer" enable the release of the drugs into the environment, researcher Emma Rosi-Marshall tells CNN.

The victims? Any living presence in those streams from moss to water bugs—and the creatures that eat them like fish and birds. A 2014 study found that meds flushed into the environment could be causing a global wildlife crisis, reported the Guardian.

What's new about this study, explain the researchers, is that "few [others] have examined the ecological effects of illicit drugs"; they describe amphetamine, which is used to treat ADHD, as a "potentially illicit drug." In order to measure the impact of the drugs they detected, the researchers created an artificial stream and laced it with the same levels of drugs they found in nature.

Within weeks, insects showed signs of altered development and drugs suppressed the growth of biofilms, the organisms that coat rocks, the authors write in the journal Environmental Science and Technology.

The study underscores the importance of investing in "our aging underground water infrastructure," says Rosi-Marshall. (Microbes may be doing something wild in our sewage.)

This article originally appeared on Newser: Baltimore Streams Tainted by Amphetamines