Antibiotics in World Rivers Exceed Safe Levels

By Gina Wynn

In a first-ever study of rivers in 72 countries across six continents, researchers found that concentrations of antibiotics exceeded safe levels by up to 300 times in some areas.

The research, which looked for 14 commonly used antibiotics in global waterways, was led by the University of York in the U.K. John Wilkinson, PhD, from the Department of Environment and Geography, coordinated the efforts that found significant amounts of antibiotics in 65 percent of the sites monitored.

“Safe” levels of the pollutant in rivers as determined by the AMR Industry Alliance range from 20 to 32,000ng/L depending on the antibiotic.

Offending Antibiotics

An antibiotic used to treat bacterial infections, Metronidazole, surpassed safe levels by the highest margin (300 times) in one river in Bangladesh. This was 170 times higher than the total antibiotic concentration of 233ng/L in the River Thames and a tributary in London.

Trimethoprim for treating urinary tract infections was detected at the most sites: 307 of 711 tested. Another drug to fight bacterial infections, Ciproflaxacin, exceeded safe levels most often, showing up in 51 locations.

Problematic Sites

The University of York study showed that antibiotic contamination is a global problem with Asia and Africa leading the way. Tests in these countries resulted in the highest levels: Bangladesh, Kenya, Ghana, Pakistan, and Nigeria.

They also found high contamination levels in Europe, North America, and South America, however. Austria was the biggest European offender. And the most problematic sites were usually next to wastewater treatment systems or sewage dumps and in areas of political unrest like the Israeli/Palestinian border.

"Until now, the majority of environmental monitoring work for antibiotics has been done in Europe, North America, and China. Often on only a handful of antibiotics,” said Wilkinson. "Our study helps fill this key knowledge gap with data being generated for countries that had never been monitored before."

Logistical Challenge

To gather information for the study, Wilkinson’s team flew 92 sampling kits to partners around the world who took water samples from their local river systems, including the Chao Phraya, Danube, Mekong, Seine, Thames, Tiber, and Tigris. They froze the samples and sent them back to the University of York for analysis.

According to Wilkinson, no other studies of antibiotics in the environment have been done on this scale.

Antimicrobial Resistance

"The results are quite eye opening and worrying, demonstrating the widespread contamination of river systems around the world with antibiotic compounds,” said Alistair Boxall, PhD, Theme Leader of the York Environmental Sustainability Institute.

"Many scientists and policy makers now recognize the role of the natural environment in the antimicrobial resistance problem. Our data show[s] that antibiotic contamination of rivers could be an important contributor."

Boxall added that solving the problem is going to be a mammoth challenge. He believes it will take global investment in infrastructure for waste and wastewater treatment, tighter regulations, and the cleanup of already contaminated sites.