Steam rises from garbage and a polluted river.
Steam rises from garbage at the Odaw River in Ghana. Credit: Richard Marchant

In a photograph, steam rises from a pile of garbage that sits by a river. The river is the Odaw, in Ghana, near the country’s capital city of Accra, and in the photo the Odaw’s water is black.

“They refer to it as a dead river.”

“They refer to it as a dead river,” said Alistair Boxall, who is an environmental chemist at the University of York in the United Kingdom.

The person who took the photo is ecologist Robert Marchant, also of the University of York. Marchant was at the river to take a sample of the water as part of a global campaign, led by Boxall, to study concentrations of pharmaceuticals in the world’s rivers. Boxall, along with his colleague John Wilkinson, coordinated an international team that sampled rivers like the Odaw.

“We wanted to try and get a better understanding of what the levels of pharmaceuticals, including antibiotics, were around the globe,” Boxall said.

Boxall and Wilkinson sent their collaborators a box that contained sample vials, syringes, filters, and freezer packs. The collaborators sampled 711 river locations in 72 countries and then sent their samples back to Wilkinson and Boxall for analysis.

What Wilkinson and Boxall found is that 470 of those sites contained antibiotics, which come from sources including human excrement and drug manufacturing activity. Many of these antibiotics occur at concentrations above what the Antimicrobial Resistance (AMR) Industry Alliance—a group of private sector companies that aims to address the threat of antibiotic-resistant bacteria—says is safe. Here “safe” refers to those levels above which the alliance says bacteria can start to develop antibiotic resistance. According to Boxall, those levels can range anywhere from 20 to 32,000 nanograms per liter of water, depending on the antibiotic.

Doctors use antibiotics to treat a raft of bacteria-caused ailments, from tuberculosis to staph infections. Some bacteria can become antibiotic resistant when exposed to the drugs, which can make treatment next to impossible for doctors. In the United States alone, according to the Centers for Disease Control and Prevention, 23,000 people die each year from antibiotic-resistant bacterial infections.

The Kirtonkhola River in the city of Barishal, Bangladesh, was one of the sites where samples were collected for the Global Monitoring of Pharmaceuticals Project. Credit: Tapos Kormoker

At Ghana’s Odaw River, concentrations of antibiotics like metronidazole, used to treat things like skin and mouth infections, exceeded safe levels by a factor of 68. The Odaw, though, is not the worst-off river. More than 110 of the 711 sampled sites have concentrations that exceed safe levels by factors of up to 300. Rivers in Bangladesh, where concentrations hover around 40,000 nanograms per liter, are among the worst of that group.

“People are using these rivers to clean in, clean their clothes in. They’re sourcing their water from those sites,” said Boxall, who presented results from the campaign earlier this month at the Canadian Chemistry Conference and Exhibition in Quebec City. This means that people who use the rivers stand a greater chance of exposing themselves to the resistant bacteria.

The campaign helps address the threat that such bacteria pose by revealing what the prevalence of pharmaceuticals is in rivers around the world—something that should help prioritize which drugs merit the most attention when it comes to cleanup efforts.

Acquiring such data, however, would not have been possible without the global, standardized campaign conducted by Boxall and Wilkinson, according to environmental engineer Viviane Yargeau of McGill University in Canada, who was not involved in the study. “You know that you’re comparing apples and apples,” she said.

—Lucas Joel, Freelance Journalist


Joel, L. (2019), Antibiotics are flooding Earth’s rivers, Eos, 100, Published on 05 July 2019.

Text © 2019. The authors. CC BY-NC-ND 3.0
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