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Erinn Richmond is collecting aquatic invertebrates for pharmaceutical analysis at Brushy Creek, Churnside Park, Victoria, Australia. Credit: Keralee Browne.
Sixty-nine pharmaceutical compounds have been detected in water-course insects, some at concentrations that may threaten animals that feed on them, such as trout and platypus. When these insects become flying adults, they can transmit drugs to spiders, birds, bats and other browsers at the edge of the water. The results of an international team of researchers were published today in Nature Communications.
Pharmaceutical pollution is present in surface waters around the world. Drugs enter the environment because most wastewater treatment facilities are not equipped to dispose of them from wastewater. Septic tanks, aging pipes and sewer overflows contribute to the problem.
Emma Rosi, aquatic ecologist at the Cary Ecosystems Studies Institute and co-author of the paper, explains, "Life in the water courses is bathed in a mix of pharmaceuticals. Our study is the first to show that this chronic drug pollution can focus on aquatic insects and move up the food chains, exposing in some cases the main predators to therapeutically relevant doses. "
Monitor pharmaceuticals in water courses
The team analyzed six feeds to 98 pharmaceutical compounds in Melbourne, Australia – the most comprehensive screening to date. The measured pharmaceuticals included common drugs such as antibiotics, antidepressants, antihistamines, and NSAIDs. The study sites were selected according to a sewage contamination gradient comprising a site downstream of a sewage treatment plant and a site in a national park.
Starting with filtering insects, the pharmaceutical compounds found in the water of the water courses accumulate in the tissues of aquatic organisms. This means that animals that eat aquatic insects, such as platypus, receive a dose of pharmaceuticals with their meals. Credit: Denise Illing
Aquatic insects and riparian spiders were collected. Erinn Richmond, a freshwater ecologist at Monash University in Australia and lead author of the study, explains, "We focused on riparian spiders because they build their canvases over the water. water courses and feed on adult aquatic insects as they exit the water. "
Bugs on drugs
Tissue analyzes detected up to 69 different pharmaceutical compounds in aquatic insects and up to 66 compounds in riparian spiders. Drug concentrations were highest in invertebrates collected downstream of wastewater treatment facilities or in highly populated areas with potential leaks in septic tanks. On average, pharmaceutical concentrations at these sites were 10 to 100 times higher than at less contaminated sites.
Co-author Jerker Fick, a chemist at the University of Umeå in Sweden, analyzed the insect and spider samples. "The insect concentrations in insect tissues were several orders of magnitude higher than those measured in surface waters." We also found a variety of substances in spiders, indicating that these substances are passed from water to their predators, thus exposing other animals in the web food to the drug. "
"Pharmaceuticals were present in all the insects and spiders we tested, including those collected in Dandenong Range National Park," notes Richmond. "Even this seemingly pristine site has been contaminated, probably because people live in the park's drainage area and visit the park."
Spiders of the family Tetragnathidae, such as the one pictured here, are present in riparian environments around the world. They build their canvases over water courses and catch aquatic insects when they emerge from the water. Pharmaceutical products in insects spread to spiders and other organisms on Earth. Credit: Stephen Hamilton.
Top predators are at risk
In the watercourses studied, platypus and brown trout also feed on aquatic insects. By combining concentrations of pharmaceuticals found in insects from rivers with known dietary needs in platypus and trout, the team was able to estimate their exposure to the drug.
Rosi explains: "A platypus living in a creek receiving a treated sewage effluent could receive the equivalent of half a human dose of antidepressant recommended every day, simply by eating its normal diet of creek insects.This intake could have biological effects. "
Next steps
Phrygane, a worldwide aquatic insect, was among those tested in this study. According to Richmond, "Similar insects are found in fresh waters around the world, this problem is not specific to Australia, it is representative of what is likely happening wherever people take drugs. And it's probably an underestimate – we've only tested 98 pharmaceutical compounds – there are thousands in circulation. "
Rosi concludes: "The use of pharmaceuticals is increasing around the world.It is clear that the medicines we take enter the freshwater and are transferred into the food chain.We do not know the ecological consequences of the Exposure to this pollution What does it mean to be a platypus or trout with more than 60 medications in your tissues? Are there synergistic effects? Further research is needed on the extent of food web contamination and on the effects of these compounds on fish and wildlife. "
Explore further:
Constant and low-dose drip: pollution from pharmaceuticals and personal care has an impact on aquatic life
More information:
A diverse range of pharmaceuticals contaminates the food webs of rivers and riparian areas, Nature Communications (2018). DOI: 10.1038 / s41467-018-06822-w, https://www.nature.com/articles/s41467-018-06822-w
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