In the months leading up to the Paris Games, one of the biggest questions was not just which athletes would compete, but whether the River Seine would be safe enough to welcome them in some of the swimming events.
As the Games progressed, speculation only intensified. Ahead of the men’s and women’s individual triathlons on July 31, the swimming portions of the training sessions were canceled due to concerns about water quality, and when the events finally took place on July 31, the athletes were…less than thrilled by the conditions. Then, news broke over the weekend that several competitors fell ill after swimming in the Seine.
On August 4, Belgium even pulled out of the mixed relay event scheduled for the following day after 35-year-old Claire Michel contracted what the Belgian publication By default reported was a E. coli infection. While it’s unclear whether her illness is related to any of the other cases (and whether any of them were caused by swimming in dirty water), the development highlights the safety concerns that athletes and public health experts have been expressing since it was announced that some Olympic events would be held on Paris’ iconic canal.
“Swimming has been banned in that river for about a hundred years because it is notoriously dirty,” Bill Sullivan, PhDa microbiologist and professor at Indiana University School of Medicine, tells SELF. “There’s a lot of sewage that seeps into the river. And there’s a lot of erosion that occurs with the soil washing potential animal feces into the water as well.” Combined, these two factors can cause a lot of nasty things, like E. colithe parasites Cryptosporidium It is Giardia, and a number of other insects, according to Dr. Sullivan.
And while you might think the risk goes down after a downpour—fresh water is good, right?!—the opposite is true, according to Dr. Sullivan. Heavy rain is a really big risk factor, he says, especially in older cities like Paris that have more antiquated sewage systems, because the resulting flooding washes all the waste from the land into the river. With that in mind, it’s worth noting that it rained in the days leading up to the triathlons, even during the opening ceremony.
However, the athletes were able to swim the Seine after last-minute test results were deemed “compliant” by World Triathlon, the sport’s governing body, according to NBC. Then the mixed relay event scheduled for August 5 went ahead as planned when officials — including representatives from World Triathlon and the International Olympic Committee — met over the weekend to review the latest water quality tests, which showed that bacteria counts were within required limits, as Associated press reported.
But even a stellar test result isn’t a conclusive guarantee of swimming safety: The tests actually only target certain species of fecal bacteria, effectively using E. coli as a proxy for other insects, Dr. Sullivan says. In most circumstances, that’s “probably OK, but it’s not a 100 percent guarantee that the water is free of some of these other pathogens as well.” Overall, he says, the whole swimming situation makes him “very nervous.”