Recent tests found hazardous levels of viruses and bacteria from sewage in Rio de Janeiro’s waters, where athletes will compete in swimming and boating events at the 2016 Olympics, according to an AP investigation published Thursday. The results underscore international concerns about health risks for nearly 1,400 Olympians using Rio’s polluted waters during the event as well as tourists visiting Brazil’s iconic beaches. Though Brazilian authorities have vowed to clean up its waterways, AP testing over five months did not find one venue with water quality fit for swimming and boating. Test results found high counts of active and infectious human adenoviruses, which may cause diarrhea, vomiting, respiratory issues, and other illnesses, according to the AP. Concentrations of the human adenoviruses were comparable to that seen in raw sewage.