The study involved 72 countries and 711 sampling locations. The report said that at a section of the river in Austria, the Danube contained seven different types of antibiotics, including clarithromycin for pneumonia and bronchitis. The concentration of chemicals was four times higher than the safe thresholds, it added.

“It’s quite scary and depressing,” Alistair Boxall, an environmental scientist at the University of York and the studyʼs co-author, told British newspaper The Guardian. “We could have large parts of the environment that have got antibiotics at levels high enough to affect resistance.”

The contamination level of the Danube is surprising for researchers, as only 8% of the examined rivers exceeded safe antibiotics levels in Europe. For the most part, antibiotics input derives from inadequate wastewater treatment near rivers, the study says.