Canadian triathlete did not vomit because of the Seine's water quality

Canadian triathlete Tyler Mislawchuk gained social media fame after a video surfaced of him vomiting during the running portion of the triathlon on July 31, 2024. Posts quickly blamed the Seine's water quality (archived here and here), which is notorious for its high pollution levels. Despite €1.4 billion allocated for river cleanup before the Olympics and the city's mayor swimming in the Seine to prove its safety, doubts about the water's condition persist.

However, Mislawchuk himself cited swallowing a lot of water and the heat as the cause. The temperature in Paris was 32°C during the race.

Closer look

Several triathletes dropped out of the mixed relay due to illness after swimming in the Seine during the Olympic triathlons. The source of illness has not yet been confirmed for many of these athletes. 

Belgium's Claire Michel stated on her Instagram that her illness was caused by a virus, not E. coli, which is often linked to poor water quality.

Switzerland's Adrien Briffod developed a "gastrointestinal infection," and Swiss Triathlon stated it's unclear if it was related to the Seine's water.

Norwegian triathlete Vetle Bergsvik Thorn also fell ill after competing, leading to Norwegian Triathlon Federation's Arild Tveiten speculating it might be the river or food poisoning. "We're thinking what everyone is thinking: that it's probably the river. But we don't know," Tveiten told Norwegian broadcaster NRK. "The doctor is leaning toward the possibility of food poisoning. That's what the symptoms suggest."

Canadian Tyler Mislawchuk told Triathlon Magazine, "I vomited 10 times after the race… it got hot in the last laps." He added, "I'm just a kid from Winnipeg, well, specifically Oak Bluff, where it's –50 in the winter, and I'm here at the Summer Olympics."

Later, he commented for CBC, "I happened to swallow a lot of water during the race. Nothing to do with the quality. My stomach was just extremely full."

Neither the media nor the athlete's team reported any health deterioration post-race.

Nausea and vomiting are common gastrointestinal symptoms in endurance athletes and are physiological reactions to strenuous exercise. Between 50 and 80 percent of ultra-endurance runners experience nausea, vomiting, and/or diarrhea.

French authorities do not blame the Seine. "For the moment, there is no direct link between the Seine and any illness," said Pierre Rabadan, Paris deputy mayor in charge of the Olympics.

The Summer Olympics are increasingly challenging due to heat; temperatures of 35°C are forecast in Paris at the time of writing. The 2021 Tokyo Olympics, the "hottest in history," regularly saw temperatures above 34°C. Then, Norwegian triathlete Kristian Blummenfelt was taken away in a wheelchair after he won his gold and then vomited and collapsed.

The verdict

Canadian athlete Tyler Mislawchuk attributed his sickness to excessive heat and the amount of water he swallowed, not its quality. No health deterioration was reported post-race. Nausea and vomiting are common in endurance sports. Thus, the claim has been marked as misleading.