Traces of amphetamines alter stream ecology, study shows
When sewage leaks, Baltimore’s waterways are not just fouled by the waste. They also become contaminated with residues of pharmaceuticals, personal care products and even illicit drugs, researchers say.
Traces of amphetamines from prescription drugs and methamphetamine make algae produce less oxygen, speed the growth of midge flies and change the mix of bacteria on stream bottoms, according to scientists who have been gathering data from the Gwynns Falls for nearly two decades.
While drugs have long been detected in urban waterways, the researchers have shown for the first time that the chemicals can cause reactions up the food chain.
“We have not done this kind of research before,” said EmmaRosi-Marshall, an aquatic ecologist at the Cary Institute of Ecosystem Studies in New York and co-director of the Baltimore Ecosystem Study. “We didn’t know this was the case.”
Scientists say that while they do not yet understand how the cocktail of chemicals carried in human waste affects streams in combination, they can infer that the drug residues are having an ecological impact.
Over the past 18 years, researchers have been studying the Gwynns Falls through the Baltimore Ecosystem Study. The National Science Foundation-funded project has produced similar research papers explaining the effects of antibiotics, antibacterial soaps and antihistamines on aquatic ecosystems.
In this case, researchers built eight artificial streams in a lab at the Cary Institute. Half served as control subjects, and the others were exposed to amphetamines at concentrations similar to those found in the Gwynns Falls. The researchers found a clear difference from the presence of amphetamines, a type of stimulant. The results were published this month in the journal Environmental Science & Technology.
In the layer of single-cell algae and bacteria that makes stream beds so slick — known as biofilm — they found the drugs’ presence stunted photosynthesis and changed the mix of organisms present. The biofilm is a key food source for insects that sustain fish, spiders, birds and bats. The amphetamines also affected the insects’ growth.