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Much of the world’s human population has some sort of pharmaceutical running through their veins, and as it turns out, so does the planet’s streams and rivers. According to a report published in Ecological Applications by the Cary Institute of Ecosystem Studies, drugs and other chemicals have found their way into the freshwater supply and are affecting the health of the ecosystem. The study looked at six common compounds and how they altered the aquatic organisms that create the slippery “biofilm” that covers rocks. Scientists found a dramatic decrease in algal photosynthesis and respiration as well as a change in the bacterial community.

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Lead author Dr. Emma Rosi-Marshall and her colleagues from Indiana University and Loyola University in Chicago took samples of biofilm from streams in Maryland, New York and Indiana. Testing for compounds including allergy meducation, caffeine, heartburn drugs, and antibiotics, they charted the effects the chemicals had on the communities of fungi, algae, and bacteria vital for the cycling of nutrients and acting as the basis of the food chain. They found antihistamines decrease the rate of photosynthesis by an incredible 99 percent in algae and also caused significant drops in respiration. The drug diphendhyramine in particular changed the types of bacteria present in the biofilm, increasing a group known to degrade toxic compounds and decreasing bacteria that digests the products of algae and bacteria.

Pharmaceutical pollution is now detected in waters throughout the world. 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.” Said Dr. Rosi-Marshall.

The results of the study suggest that diphenhydramine is commonly found in the environment and is disturbing the food web. Other pharmaceuticals that were investigated both alone and in combination with one another also were shown to create changes in photosynthesis and respiration. While more work needs to be done to understand how different levels and concentrations of the chemicals impact the ecosystem, the study brings to light the dependence humans have on drugs and how that relationship has influenced the water supply for all organisms. New innovations in waste treatment will have to take into account the presence of these pharmaceuticals in order to provide safe sources of fresh water in the future.

+ Cary Institute of Ecosystem Studies


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