Sylvia Lee, PhD, is a scientist at the Cary Institute of Ecosystem Studies in Milbrook, New York. She has access to an unusual—yet essential—set of laboratory equipment: a whole greenhouse filled with white fiberglass bathtubs. There’s no mistaking these vessels with those you’d find in the average bathroom, however. While these bathtubs are about the same length, they’re shallower, narrower, and have a raised racetrack-like interior that water circulates around. And none of the lab members spend time inside them.

Instead, researchers fill them with rocks and organisms obtained from local streams in upstate New York. And in place of bubble bath, they add to the water D-amphetamine, the same active substance found in several ADHD and narcolepsy medications. The water in the tubs is mixed with enough amphetamines to make the organisms think they’re sitting downstream from one of Baltimore’s water treatment plants. The goal of this lab is to find out what the US’ heavily medicated population might be doing to its surroundings.

The United States of America is a highly medicated country: almost seven in 10 Americans take prescription drugs. That translates to 4.4 billion prescriptions and nearly $310 billion spent on medication in 2015. Painkillers, cholesterol-lowering medications, and antidepressants top the list of drugs most commonly prescribed by doctors.

Needless to say, the work of biologists like Lee may prove to be crucial.

Where drugs go after we’re done with them

Americans aren’t just putting these drugs into their bodies; they’re also putting more drugs into the environment. A growing body of research suggests all types of drugs, from illegal drugs to antibiotics to hormones, enter the environment through sewage and cesspool systems across the country. And while pharmaceutical drugs—when used as prescribed—are capable of curing disease and alleviating symptoms in people, they can wreak havoc on nature.

There, they persist for long periods without breaking down. Hormones in medications like birth control cause changes such as intersex development in fish and amphibians. Antidepressants have been found in the brain tissue of fish downstream from wastewater treatment plants. Research on the presence of illegal drugs in water bodies has revealed some interesting trends: drug concentrations are highest on weekends and skyrocket after social events, such as music festivals, where large quantities of drugs are often consumed.

Amphetamines, a class of both legal and illegal stimulant drugs, also appear to have an effect on aquatic ecosystems, according to new research. For people with Attention Deficit Hyperactivity Disorder (ADHD), amphetamines can mean the difference between extreme distraction and intense focus. For people seeking an illicit high, amphetamines like meth and amphetamine-related drugs like ecstasy result in an overwhelmingly euphoric—often dangerous—high.

In 2012, 16 million people were prescribed legal amphetamines in the United States, and about 1.2 million people took illicit methamphetamine. Hundreds of thousands took prescription amphetamines illegally or in an addictive manner.

In June 2013 and June 2014, Lee (whose research focuses on how human activities affect urban streams) led an international group of scientists in collecting water samples at six stream sites in Baltimore, Maryland. They found 14 different drugs, including amphetamines and methamphetamines, in varying concentrations at all six test sites.

According to Lee, “We detected higher amphetamine concentrations than those found previously [by researchers in Spain] in surface waters,” which had previously held the record for the highest concentration of amphetamines in surface waters ever recorded. “We expected the concentration of amphetamine in Baltimore streams to be higher because there is untreated sewage entering these streams. However, it is notable that even low concentrations of amphetamine and other pollutants may change stream ecosystems.”……more here