Streams Stressed by Pharmaceutical Pollution

Antihistamines Alter Sensitive and Essential Habitat

 

Pharmaceuticals commonly found in the environment are disrupting streams, with unknown impacts on aquatic life and water quality, according to a new ecological applications paper released by the Cary Institute of Ecosystem Studies in Millbrook, N.Y.

The paper, written with input from researchers at Indiana University and Loyola University Chicago, highlights the ecological cost of pharmaceutical waste and the need for more research into environmental impacts. Globally, lakes and rivers are polluted by an array of pharmaceutical and personal care products. Freshwater fish and the invertebrates they eat are increasingly bathed in a weak solution of caffeine, estrogen, antibiotics, and antihistamine drugs – but little is known about the levels at which these compounds become toxic or lethal, or what the effect on our drinking water may be.
 “Pharmaceutical pollution is now detected in waters throughout the world,” said lead author Dr. Emma Rosi-Marshall, a scientist at the institute. “Causes include aging infrastructure, sewage overflows, and agricultural runoff. Even when wastewater 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.”

With colleagues from IU and Loyola, Rosi-Marshall looked at how six common pharmaceuticals influenced similar-sized streams in New York, Maryland, and Indiana. Caffeine, the antibiotic ciprofloxacin, the antidiabetic metformin, two antihistamines used to treat heartburn (cimetidine and ranitidine), and one antihistamine used to treat allergies (diphenhydramine) were investigated, both alone and in combinations, using pharmaceutical-diffusing substrates.

“We focused on the response of biofilms – which most people know as the slippery coating on stream rocks – because they’re vital to stream health,” Rosi-Marshall said. “They might not look like much to the naked eye, but biofilms are complex communities composed of algae, fungi, and bacteria all living and working together. In streams, biofilms contribute to water quality by recycling nutrients and organic matter. They’re also a major food source for invertebrates that, in turn, feed larger animals like fish.”

Healthy streams are slippery streams, Rosi-Marshall said. And it turns out that antihistamines dry more than our noses. The most striking result of the study was diphenhydramine’s effects on algal production and microbial respiration. Exposure caused biofilms to experience up to a 99 percent decrease in photosynthesis, as well as significant drops in respiration. Diphenhydramine also caused a change in the bacterial species present in the biofilms, including an increase in a bacterial group known to degrade toxic compounds and a reduction in a group that digests compounds produced by plants and algae.

Results suggest that this antihistamine is disrupting the ecology of these sensitive biofilm communities. “We know that diphenhydramine 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. We need additional studies looking at the concentrations that cause ecosystem disruption, and how they react with other stressors, such as excess nutrients.”

The other pharmaceuticals investigated also had a measurable effect on biofilm respiration, both alone and in combinations. More work is needed to understand how drug mixtures, which most natural streams experience, impact freshwater systems, the report noted.

Society’s dependence on pharmaceuticals is not likely to wane. Nor is its need for clean, fresh water. This study adds another piece of evidence to the case calling for innovations in the way we manage wastewater, Rosi-Marshall said. Currently, only a fraction of the world’s wastewater is treated, and the infrastructure in many developed nations is aging, she said.

Rosi-Marshall received funding from the Wallace Genetic Foundation, Inc. and the Cornell-Douglas Foundation to help build an artificial stream facility on the Cary Institute's campus, to facilitate the research. She said few places exist without some level of these contaminants, so scientists need artificial streams to serve as control waters for research.

Contributors to the project included Dustin Kincaid and Heather Bechtold of the Cary Institute of Ecosystem Studies, Todd V. Royer from the School of Public and Environmental Affairs, Indiana University, and Miguel Rojas and John J. Kelly from the Department of Biology, Loyola University Chicago.

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