Just days ahead of the Olympic Games the waterways of Rio de Janeiro are as filthy as ever, contaminated with raw human sewage teeming with dangerous viruses and bacteria, according to a 16-month-long study commissioned by The Associated Press.

Not only are some 1,400 athletes at risk of getting violently ill in water competitions, but the AP’s tests indicate that tourists also face potentially serious health risks on the golden beaches of Ipanema and Copacabana.

The AP’s survey of the aquatic Olympic and Paralympic venues has revealed consistent and dangerously high levels of viruses from the pollution, a major black eye on Rio’s Olympic project that has set off alarm bells among sailors, rowers and open-water swimmers.

The first results of the study published over a year ago showed viral levels at up to 1.7 million times what would be considered worrisome in the United States or Europe. At those concentrations, swimmers and athletes who ingest just three teaspoons of water are almost certain to be infected with viruses that can cause stomach and respiratory illnesses and more rarely heart and brain inflammation — although whether they actually fall ill depends on a series of factors including the strength of the individual’s immune system.

Since the AP released the initial results last July, athletes have been taking elaborate precautions to prevent illnesses that could potentially knock them out of the competition, including preventatively taking antibiotics, bleaching oars and donning plastic suits and gloves in a bid to limit contact with the water.