Researchers estimate presence of 14 antibiotics in rivers of 72 countries across six continents
An assessment of antibiotic pollution in rivers across the world shows that the concentration of antibiotics in some rivers is much higher than what is considered safe. According to the antimicrobial resistance (AMR) industry alliance standards, the safe level ranges from 20-32,000 nanogramme per litre, depending on the antibiotic.
However, in Bangladesh, the antibiotic metronidazole was found to 300 times the safe level — this was 170 times higher than what was estimated in London’s River Thames.
The researchers — who presented their findings at the two day annual meeting of the Society of Environmental Toxicology and Chemistry (SETAC) in Helsinki, which began on May 27 — estimated presence of 14 antibiotics in rivers of 72 countries across six continents.
A total of 711 sites were tested and antibiotics were found at 65 per cent of them. Trimethoprim, an antibiotic used to treat urinary tract infection, was found at 307 of the 711 sites tested. Ciproflaxacin most frequently exceeded safe levels, surpassing the safety threshold at 51 places.
The team found that safe limits were most frequently exceeded in Asia and Africa, but sites in Europe, North America and South America also had high level. Sites where antibiotics exceeded the safe levels were primarily in Bangladesh, Kenya, Ghana, Pakistan and Nigeria.
The study revealed that high-risk sites were typically adjacent to wastewater treatment systems and waste or sewage dumps. Some of the world's most iconic rivers were sampled, including the Chao Phraya, Danube, Mekong, Seine, Thames, Tiber and Tigris.
The research was led by the University of York. Partners across the world were asked to take samples from locations along their local river system. These samples were then frozen and couriered back to the University of York for testing.
According to John Wilkinson, from the Department of Environment and Geography, this is the first time that a study of this scale has been conducted. Earlier studies were from Europe, North America and China, and only a handful of antibiotics have been tested for. “Our study helps fill this key knowledge gap with data being generated for countries that had never been monitored before,” he said.
“Many scientists and policy makers 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," said Alistair Boxall, theme leader of the York Environmental Sustainability Institute.
“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 added.
The study comes in wake of a commitment taken by member states at the World Health Assembly on May 23, 2019. This resolution urges member states to strengthen infection prevention and control measures, including water sanitation and hygiene; enhance participation in global antimicrobial surveillance system; ensure prudent use of quality-assured antimicrobials; and support multisectoral annual self-assessment survey.
Antibiotic resistance is rampant in India too. A study released in March 2019 showed that a large number of bacteria in River Ganga are resistant to commonly used antibiotics.
The study was done by researchers from the Banaras Hindu University who found evidence of antibiotic resistant bacteria in the water and sediment samples collected from five river banks — Assi, Bhadaini, Harishchandra, Dr Rajendra Prasad and Rajghat in Varanasi. The researchers linked the findings to domestic waste — Varanasi region receives over 309.8 million liters of treated and untreated domestic waste daily.
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