Largely ignored until now, the first-ever comprehensive report on the health of 72 rivers around the world has revealed that two-thirds of them are heavily contaminated with antibiotics.
Of the samples collected from 711 sites, 65% were found to contain at least one of the 14 antibiotics they were screened against; no continent has been spared of antibiotic pollution (Antarctic waters weren’t a part of this study).
Traces of antibiotics were found in the waters of rivers including heavyweights such as the Thames, the Tigris, the Seine, the Tiber, and the Mekong.
Dangerous levels of contamination were most frequently found in Asia and Africa, according to the team of researchers from York University, UK, with sites in Bangladesh, Kenya, Ghana, Pakistan and Nigeria exceeding safe levels by the greatest degree.
To make it worse, this is contributing to the growing problem of antibiotic-resistant bacteria, infections from which could be the leading cause of death worldwide, by 2050. Not to mention the irreversible transformation of riverine ecology it has spurred.
Life-saving drugs are changing the genetic makeup of our rivers
With the discovery of the first antibiotic, penicillin in 1928, Alexander Fleming revolutionised allopathy and public health for centuries to come, with a chemical formula that saves millions of lives from harmful infections across the world today.
But as the consumption of antibiotics increases every year, so does the volume of biologically active molecules in them being excreted into the environment through fecal waste.
There they persist for a long time and assist the development of microbes that are resistant to modern antibiotics, says Alistair Boxall, co-lead author of the study and an environmental chemist at the University of York.
Their presence — even faint traces of antibiotics in rivers — can help speed the development of resistant strains along.
Antibiotic resistance could kill us sooner than climate change
Bacteria are naturally good at genetically mutating and quickly evolving in response to a threat; this is catalysed due to the presence of antibiotics in their habitat.
In other words, as bacteria in these waterbodies evolve in response, the drugs designed to destroy them become less effective in treating infections caused by the more resistant bacteria in future.
This poses a “catastrophic threat” to doctors’ ability to treat basic infections in the future, and as resistance to commonly used medicines increases, it would not only be hard to diagnose but downright impossible.
A 2016 report found that each year around 700,000 people worldwide die of infections that are resistant to the antibiotics we have today, while a UK-commissioned study in 2014 warned that by 2050, antimicrobial-resistant infections could be the leading cause of death worldwide.
Besides its impact on human health, antibiotic pollution has also been changing the way in which bacteria in rivers cycle nutrients like carbon or nitrogen. Thereby, it disrupts the delicate ecological balances in rivers and streams, changing the makeup of bacterial communities, according to a National Geographic report.
The first global look at rivers has been quite bleak
One way out of this Catch-22 situation is to limit the effluence of excess antibiotics into natural systems like the world’s rivers. The latest study will help chart the next course of action because, so far, there is very little idea of which antibiotics are flowing in the ecosystem, where and how.
In order to map the scope of the problem, the team set about collecting samples from rivers in all continents except Antarctica, and checked them for traces of 14 commonly used antibiotics.
The water was tested in the US and the results compiled and presented at the Society of Environmental Toxicology and Chemistry, Helsinki, on Monday.
Even countries that treat wastewater at state-of-the-art plants were not able to clear away all of the drugs from their rivers; the problem was naturally more acute in places without water treatment facilities as effluents are then able to enter streams and rivers more directly.
In Bangladesh, concentrations of metronidazole, a commonly prescribed treatment for skin and mouth infections, was 300 times higher than “safe” levels, while the Danube, Europe’s second-longest river, turned up seven different types of antibiotics. Lethal concentrations of Clarithromycin, used as a treatment for respiratory tract infections like bronchitis, was found.
Researchers found Trimethoprim — a drug primarily used to treat urinary tract infections — at 43% of the river sites tested, making it the most prevalent antibiotic found in the study.
Safe levels can range from 20,000 to 32,000 nanograms per liter (ng/l), depending on the antibiotic, according to new guidelines reported by CNN.
Indian rivers and other risks
In this regard, India which enjoys a reputation for housing many rivers, has also failed to clean two of its chief Himalayan and catastrophically polluted rivers, the Ganga and the Yamuna.
The Ganga, in particular, has been described by Victor Mallet as the “Superbug river” in his book River of Life, River of Death. Along with its tributary Yamuna, the rivers play host to bacterial genes that expose the water’s users to infectious diseases resistant to modern antibiotics, writes The Caravan.
The book discusses how the rivers are helping spread “blaNDM-1—a bacterial gene that codes for a protein called NDM-1, or New Delhi metallo-beta-lactamase, and whose presence can make the carrier highly resistant to antibiotics.”
Despite poll promises, Prime Minister Narendra Modi is nowhere close to his target of cleaning the sacred river by 2020, despite backing for the project of Rs 200 billion. India’s massive sanitation problem entails that the majority of sewage still flows into its waters untreated, and pollution counts remain many times above safe limits.
“In many ways it’s like the plastic pollution problem,” says Boxall. “The issue is we don’t think about where our waste goes, and that it has a life beyond us.”
Besides discharge of domestic waste, medicinal and industrial effluents into rivers, other threats to the world’s water systems are posed by modern phenomena like the globalisation of food trade, excessive harvesting of water for irrigation and industrial purposes, multi-purpose projects like the dams and diversions, among others.
Prarthana Mitra is a Staff Writer at Qrius.