The concentration of antibiotics found in some of the world‘s rivers has exceeded levels considered to be safe by up to 300 times, and could contribute to the emerging global health crisis caused by antimicrobial resistance, a new study has found.
The study led by the University of York in the U.K. examined the concentrations of 14 commonly used antibiotics in rivers in 72 countries on six continents and detected antibiotics at 65 per cent of the sites monitored.
Researchers compared the data with levels established by the Antimicrobial Resistance Industry Alliance, which outlines the “safe range” as anywhere from 20,000 to 32,000 nanograms per litre (ng/l) of water depending on the antibiotic.
What researchers found
The study found metronidazole, which is used to treat bacterial infections such as skin and mouth infections, exceeded safe levels by the largest margin. At one site in Bangladesh, metronidazole was found in concentrations 300 times greater than the safe level.
According to the study, in the River Thames and one of its tributaries in London, researchers detected a maximum total antibiotic concentration of 233 ng/l — well within the safe range.
However, in Bangladesh, the study found the concentration was 170 times higher.
Researchers also detected trimethoprim — a drug primarily used to treat urinary tract infections — at 307 of the 711 sites, making it the most prevalent antibiotic found during the study.
The study found ciprofloxacin, used to treat a number of bacterial infections, was the antibiotic found most frequently exceeding safe levels, surpassing the safety threshold at 51 of the monitored sites.
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Researchers found that antibiotics exceeded safe levels by the greatest degree at sites in Bangladesh, Kenya, Ghana, Pakistan and Nigeria. However sites in Europe, North America and South America also recorded levels of concern.
The study also revealed that high-risk sites were most often found adjacent to wastewater treatment systems or waste or sewage dumps and in some areas of political turmoil.
How Canada measures up
According to Dr. John Wilkinson, from the University of York’s department of environment and Geography, while 15 per cent of the sites studied in North America exceeded the safe range, none of those sites were in Canada.
Wilkinson, who co-ordinated the study’s monitoring work, told Global News researchers collected samples in Toronto, Calgary and Ottawa, and did detect antibiotics at each of the sites, however, they did not exceed the ‘safe’ threshold.
This, Wilkinson says, is largely due to Canada’s effective wastewater treatment infrastructure.
Water contamination and the effect on humans
A December 2017 report from UN Environment found when antimicrobial compounds from households, hospitals, pharmaceutical facilities and agricultural run-off released into the environment came into direct contact with natural bacteria it resulted in bacterial evolution and the emergence of more drug-resistant strains.
“Once consumed, most antibiotic drugs are excreted un-metabolized along with resistant bacteria – up to 80 per cent of consumed antibiotics,” the report reads.
With human antibiotic use having increased 36 per cent in the 21st century, and the use of livestock antibiotics predicted to increase by 67 per cent by 2030, the problem is a growing one, the report says.
According to the report, up to 75 per cent of antibiotics used in aquaculture may be lost into the surrounding environment.
Additionally, the report says wastewater treatment facilities are unable to remove all antibiotics and resistant bacteria, and in some cases, could become hotspots for antimicrobial resistance.
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The University of York study found concentrations of antibiotics high enough that bacteria or pathogens exposed to the medication could become resistant.
“So say for example a person is bathing in a river comes in contact with some of these bacteria which then results an in infection, then that person taking this drug, say ciprofloxacin for example, may find that the bacteria is resistant to the effects and is unable to fight off the infection,” Wilkinson explains.
“So we could get a scenario, where we have a certain number of deaths due to treatable diseases at this point in time,” he said.
And, according to Wilkinson, it takes only a minuscule amount of an antibiotics in water for bacteria to develop resistance.
“To put it into perspective one nanogram in a litre of water is the same as putting four grains of table salt in an Olympic sized swimming pool,” he said. “So it’s incredibly small concentrations but they are still significant in terms of these bacteria being able to select resistance to these drugs.”
Antimicrobial resistance could have ‘disastrous impact’ within a generation
Last month, the Interagency Coordination Group on Antimicrobial Resistance (IACG) presented a report to the secretary-general of the United Nations calling antimicrobial resistance a “global crisis” that “threatens a century of progress in health” and achievement of the world’s Sustainable Development Goals.
The IACG report found “alarming levels” of resistance had been reported in countries of all income levels around the world, resulting in common diseases becoming untreatable and lifesaving medical procedures “riskier to perform.”
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According to the report, drug-resistant diseases cause at least 700,000 deaths globally per year, including 230,000 deaths from multidrug-resistant tuberculosis.
“There is no time to wait,” the report reads. “Unless the world acts urgently, antimicrobial resistance will have disastrous impact within a generation.”
According to the UN Environment report, in order to solve the problem, governments and organizations will need to tackle the use and disposal of antibiotic pharmaceuticals, as well as the release of antimicrobial drugs, relevant contaminants and resistant bacteria into the environment.
A ‘mammoth challenge’
Alistair Boxall, theme leader of the York Environmental Sustainability Institute, says the study’s results are “worrying” and that cleaning the contaminated rivers could be extremely difficult.
“Solving the problem is going to be a mammoth challenge and will need investment in infrastructure for waste and wastewater treatment, tighter regulation and the cleaning up of already contaminated sites,” he said in a statement.
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Wilkinson says while it is a complicated issue, there are things individuals can do to help.
“I think most people don’t know that in most countries of the world, you can bring unused medicine back to your pharmacist who will dispose of them properly instead of throwing them in the rubbish which will end up in the landfill and potentially in rivers or even flushing them down the drain which is a direct route to the rivers,” he said.
The findings of the University of York study were presented at the annual meeting of the Society of Environmental Toxicology and Chemistry in Helsinki on May 27 and 28.