Hundreds of sites in rivers around the world from the Thames to the Tigris are awash with dangerously high levels of antibiotics, the largest global study on the subject has found. Antibiotic pollution is one of the key routes by which bacteria are able develop resistance to the life-saving medicines, rendering them ineffective for human use. “A lot of the resistance genes we see in human pathogens originated from environmental bacteria,” said Prof William Gaze, a microbial ecologist at the U...