Environmental study details pharmaceutical drug contamination in Baltimore’s Gwynns Falls watershed

Much of the discussion around pollution in the Chesapeake Bay centers on loads of nitrogen and phosphorous — nutrients capable of breeding oxygen-sucking algae blooms — and on water clarity and bacteria levels. But for the past several years, a group of scientists has focused on a different contaminant with unique impacts on marine life: pharmaceutical drugs.

After people ingest medications, trace amounts remain in their waste, which head for wastewater treatment facilities that often do not remove them before releasing water into the environment, experts say.


In August, researchers from New York’s Cary Institute of Ecosystem Science, among others, released their study of chemicals in Baltimore’s Gwynns Falls watershed. After sampling six points along the river weekly for a year, the researchers found traces of 37 drugs, including antidepressants, antibiotics and painkillers. The New York-based researchers are part of the Baltimore Ecosystem Study, a long-term research project funded by the National Science Foundation that is based at University of Maryland, Baltimore County.

Most of the contamination, the researchers say, can be blamed on leaky pipes or stormwater runoff, since the watershed doesn’t have a plant that pumps out treated household water.


The result? Crawfish that act more boldly, quickly leaving sheltered areas and spending more time looking for food, after two weeks of exposure to antidepressants. Aquatic insects that emerge later than normal after exposure to amphetamines. Algae that photosynthesizes more quickly.

Scientists have determined those consequences can play out even when there are low concentrations of pharmaceuticals in the water, like those detected in the Gwynns Falls — as little as a nanogram per liter.

“It’s the equivalent of a pinch or a few inches of salt in an Olympic-sized swimming pool,” said Megan Fork, the lead researcher. “That sounds like it’s very small, but these are chemicals that are designed to affect a biological change at really low, dilute concentrations.”

And it’s important to remember, Fork said, the creatures exposed to doses of Advil, TYLENOL and the rest are small. And while some studies have illuminated the effects of particular pharmaceuticals on certain organisms, little is known about how an ever-changing cocktail of drugs impacts stream-dwellers, said Emma Rosi, another researcher on the study.

“There’s a changing composition of pharmaceuticals from week to week in these streams,” Rosi said. “We don’t know what that does to the organisms. We don’t know how that does or does not alter the ecosystems.”

For consumers, the lesson is fairly simple: don’t flush expired or unused pills down toilets or sinks. There are larger lessons for public officials, Fork said.

“There are next-generation technologies that can help remove some more of these pharmaceuticals and personal care products before that water gets returned to the environment,” Fork said. “So, we should be pushing for that kind of technology to be implemented, as well as kind of repairing and replacing the broken pipes.”

Baltimore County, where part of the Gwynns Falls watershed lies, is working to address pipe infrastructure. About 60% of water and sewer pipes are more than 50 years old, said Lauren Buckler, deputy director of county department of public works and transportation.


The jurisdiction has spent more than $1 billion on repairs under a consent decree it’s operated under for years that mandates fixes. That includes $58.8 million on projects in the Gwynns Falls and Dead Run sewer-sheds, she said.

“It’s a challenge that Baltimore County is addressing from an infrastructure perspective,” she said. “But it’s more than the infrastructure. It’s sustainability in general. And everybody making good decisions about what they put in the infrastructure.”

The county is also working to find leaks more quickly, Buckler said. Previously, it would prioritize repairs based on pipes’ age. Now, it can conduct camera studies, and factor in the materials of different pipes, to target possible problem areas, she said. The county also has a team that visits homes that haven’t been billed for water to look for signs of an infrastructure issue.

It would be helpful to know where the Gwynns Falls stands compared to similar watersheds, Buckler said.

“I don’t know what the comparison is to other — if they would have checked other sewer-sheds,” she said. “To just see that number on its own: how are we really doing?”

The findings warrant some concern for the environment, said Doug Myers, Maryland senior scientist at the Chesapeake Bay Foundation, but context is critical. There’s a reason other researchers have focused on nutrient pollution as part of efforts to clean the bay, he said.


“Right now, the fish can’t breathe,” he said. “So, should we be worried about them getting cancer in 30 years? Let’s prioritize getting the fish to be able to breathe.”

With a 2025 deadline for reducing nutrient loads in the bay, policymakers and advocates have focused on big-ticket improvements to wastewater treatment plants, like Baltimore’s Headworks Project, which is meant to halt sewage overflows into local waterways.

This story has been updated to reflect that the Baltimore Ecosystem Study is a long-term research project based at the University of Maryland, Baltimore County.