High levels of antibiotics dangerously flooded hundreds of sites in rivers worldwide from the Thames to the Tigris, the largest global study on the subject evidenced the drugs in 2/3rd of test sites in 72 countries.
It is antibiotic pollution by which bacteria develops resistance to the life-saving drugs, making them ineffective for the use by humans. “A lot of the resistance genes we see in human pathogens originated from environmental bacteria,” said a microbial ecologist at the University of Exeter, Prof William Gaze who studies antimicrobial resistance, however, was not involved in the study.
According to the UN’s statement last month, the rise in antibiotic-resistant bacteria is a global health emergency which could kill 10 million people by 2050.
The drugs are reaching rivers and soil through human and animal waste and leaks from drug manufacturing facilities and wastewater treatment plants. “It’s quite scary and depressing. We could have large parts of the environment that have got antibiotics at levels high enough to affect resistance,” said Alistair Boxall, an environmental scientist at the University of York, who co-led the study.
As per the research presented on Monday at a conference in Helsinki, some of the famous rivers in the world, including the Thames, are contaminated with antibiotics classified as critically important for the treatment of serious infections. They were detected even at unsafe levels in many cases which indicate that resistance is much more likely to develop and spread.
Samples taken from Austria’s Danube contained seven antibiotics, including clarithromycin used for the treatment of respiratory tract infections (RTI) like pneumonia and bronchitis, at almost four times the level considered safe.
The Danube, the second-largest river in Europe, was the most polluted river in the continent. Out of the sites tested in Europe, eight percent were above safe limits.
The Thames is generally known as one of cleanest rivers in Europe, but along with some of its tributaries, found contaminated by a mixture of five antibiotics. The pollution was above safe levels on one site on the river and three of its tributaries. Ciprofloxacin used in the treatment of infections of the skin and urinary tract found highest at three times and more than safe levels.
The rivers contaminated with low levels of antibiotics are also a threat, Gaze said. “Even the low concentrations seen in Europe can drive the evolution of resistance and increase the likelihood that resistance genes transfer to human pathogens,” he says.
The researchers found antibiotics in 65% of 711 sites in 72 countries tested by them. The concentrations of antibiotics exceeded safe levels in 111 of the sites, including the worst cases that were more than 300 times over the safe limit.
Higher antibiotic concentrations were noticed in the rivers of lower-income countries, with locations in Africa and Asia performing worst. They reach their highest point in Bangladesh, where metronidazole that is used to treat vaginal infections found at 300 times and more the safe level. The residues were detected close to a wastewater treatment facility, which often lacks the technology of removing the drugs in lower-income countries.
The high antibiotic concentrations were also witnessed at a site in Kenya that resulted in up to 100 times the safe levels due to inappropriate disposal of sewage and waste dumped directly into rivers.
“Improving the safe management of health and hygiene services in low-income countries is critical in the fight against antimicrobial resistance,” said Helen Hamilton, health and hygiene analyst at the UK-based charity Water Aid.
Now the research team is planning to assess the antibiotic pollution’s environmental impacts on wildlife, including fish, invertebrates, and algae. They expect effects to be severe. No fish could survive in some Kenyan rivers as the drug levels found were so high that “there was a total population crash,” Boxall said.