A global study has found a number of rivers in Kenya with an array of antibiotic concentration that exceed safe levels by up to 300 times.
The study whose findings were unveiled at a conference on Monday, revealed that Bangladesh, Kenya, Ghana, Pakistan and Nigeria had the highest levels of antibiotic river pollution. And within Europe, one site in Austria had the highest concentration in the continent.
The scientists found one or more common antibiotics in two-thirds of 711 samples taken from rivers in 72 countries; they told a meeting of environmental toxicologists in Helsinki, Finland.
In dozens of locations, concentrations of the medicines used to fight off bacterial infection in people and livestock exceeded safety levels set by the Antimicrobial Resistance Industry Alliance, a grouping of more than 100 biotech and drug companies.
Ciprofloxacin, a frontline treatment for intestinal and urinary tract infections, surpassed the industry threshold at 51 of the sites tested.
At a location in Bangladesh, concentrations of another widely used antibiotic, metronidazole, were 300 times above the limit, the researchers said.
“The results are quite eye-opening and worrying, demonstrating the widespread contamination of river systems around the world with antibiotic compounds,” Alistair Boxall, a scientist at the York Environmental Sustainability Institute, University of York, said in a statement.
John Wilkinson, of environment and geography department at the university, who coordinated monitoring work for the study, said: "Our study helps fill this key knowledge gap with data being generated for countries that had never been monitored before."
The study portrays a true picture of what is happening in the country.
Early this year, a study conducted by the University of Eldoret and Ghent University, Belgium, revealed an array of anti-retroviral, antibiotics, hormones, and anti-depressants in water points in Nairobi and Kisumu.
The highest concentrations being antibiotics and ARVs used to treat HIV found in rivers, waste and groundwater.
The study, "Occurrence Patterns of Pharmaceutical Residues in Waste Water, Surface Water and Ground Water of Nairobi and Kisumu", Kenya, said the concentration in water bodies of prescription and over-the-counter medicines is worrying scientists.
Mr Kenneth K’oreje, one of the authors, said people get drinking water from different sources, including rivers and boreholes, which can be contaminated.
Those using such water are exposed to drugs. “There is a 70 per cent chance that the surface and even treated water may still have traces of the drugs.
“In fact, some ARVs have resistant products that may be isolated in water long after treatment is done,” he said.
Mr K’Oreje said due to exposure to antibiotics in the water, the bacteria become hardy and when someone ingests it, he or she runs the risk of getting the resistant strain.
These drugs, measured in quantities of parts per billion or trillion, include antibiotics such as metronidazole, sulfamethoxazole and trimethoprim.
Kisumu has higher concentrations of the antibiotic sulfadoxine, which is used in combination with Fansidar to treat malaria.
When people take drugs, their bodies absorb some of the compounds and the rest are excreted.
In the global study, researchers sent out 92 sampling kits to partners across the world, who were asked to take samples from locations along their local river system.
Samples were then frozen and couriered back to the University of York for testing.
Some of the world's most iconic rivers were sampled, including Chao Phraya, Danube, Mekong, Seine, Thames, Tiber and Tigris.
"The results are quite eye-opening and worrying, demonstrating the widespread contamination of river systems around the world with antibiotic compounds," said Boxall.
"Many scientists and policymakers now recognise the role of the natural environment in the antimicrobial resistance problem. Our data show that antibiotic contamination of rivers could be an important contributor.
"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."
The widespread presence of antibiotics not only impacts wildlife but likely contributes to the problem of antimicrobial resistance.
The World Health Organisation has warned that the world is running out of antibiotics that still work, and has called on industry and governments to urgently develop a new generation of drugs.
Discovered in the 1920s, antibiotics have saved tens of millions of lives from pneumonia, tuberculosis, meningitis and a host of deadly bacteria.
Overuse and misuse of the drugs are thought to be the main causes of antimicrobial resistance.
A 2016 report found that each year about 700,000 people die globally of resistant infections because available antimicrobial drugs have become ineffective.