Pollution from common pharmaceuticals, such as antibiotics or antihistamines, damages the ecosystem of streams, according to a study conducted in the United States about the effect of pharmaceutical waste on the ecosystem of three streams in various regions in Indiana, New York and Maryland.
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The study showed that pharmaceutical waste that cannot be removed by common water treatment methods is especially harmful to biofilms, the slippery coating containing bacteria, algae, fungi and organic matter on stream rocks.
“Pharmaceutical pollution is now detected in waters throughout the world,” said the study's lead author Dr. Emma Rosi-Marshall, a scientist at the Cary Institute of Ecosystem Studies. "Causes include aging infrastructure, sewage overflows, and agricultural runoff. Even when waste water makes it to sewage treatment facilities, they aren’t equipped to remove pharmaceuticals. As a result, our streams and rivers are exposed to a cocktail of synthetic compounds, from stimulants and antibiotics to analgesics and antihistamines.”
The study entitled “Effects of Novel Contaminants, Such as Pharmaceuticals, on Stream Ecosystems” – led by Rosi-Marshall, a stream ecosystem ecologist of the Cary Institute of Ecosystem Studies in New York – examined what happened when traces of six pharmaceuticals, which were found in sewage-treatment plants, came into contact with biofilms. Biofilms are essential to stream ecosystems because they serve as the base of the food chain and also affect water quality. The medications tested – antihistamines, caffeine, a heart disease medication, an anti-biotic and a diabetes drug – are all commonly prescribed and used throughout the U.S.
The researchers took 30-milliliter cups filled with agar and added one type of pharmaceutical. (The control cups contained no drug.) Then they covered the cups with a filter on which the biofilms could grow. A steady dose of the drug emerged from the cups into the streams for 18 days.
The study, whose findings were published earlier this month in the journal Ecological Applications, shows that exposure to the drugs significantly changed the biofilm. Algal growth dropped by up to 22 percent, and photosynthesis in one stream dropped by 99 percent. Exposure to some of the drugs also caused substantial changes in the makeup of the bacteria compared with the control group.
Once the medications appear in human waste, they make their way to sewage-treatment plants, which are not equipped to deal with them. Once the sewage has been purified, it is directed, with the pharmaceutical pollution intact, to rivers and streams. The researchers say that the combination of these drugs with other pollutants such as fertilizers and pesticides could have a significant effect on the environment. “We know that diphenhydramine [one of the drugs used in the study] is commonly found in the environment,” Rosi-Marshall said. “And its effect on biofilms could have repercussions for animals in stream food webs, like insects and fish.”
Israeli scientists and the Israel Water Authority have long been concerned about the presence of medications in streams, in part because Israel uses purified sewage for irrigation. In addition, a significant portion of the water that runs through several streams comes from sewage. While the studies conducted so far have found pharmaceutical remnants in purified sewage, the effect of these substances on the environment and the concentrations at which they become an environmental hazard are not yet known.
As part of efforts to clean up the Yarkon River in Tel Aviv, a system of green basins with stones and vegetation has been established to help absorb pharmaceutical remnants.