Irish Olympic swimmer Daniel Wiffen said he was “rushed to [the] hospital” after competing in the Seine River during the 2024 Summer Olympics in Paris.

“Yesterday I rushed to hospital as I was very unwell with a bug that I am being treated for, and am feeling better now,” Wiffen wrote Sunday on Twitter, sharing he would not be at the Olympics closing ceremony where he was scheduled to be a flag bearer.

Thanks everyone who reached out, I’m incredibly disappointed to miss out on the opportunity to be flag bearer last night.

Yesterday I rushed to hospital as I was very unwell with a bug that I am being treated for, and am feeling better now. I hope everyone enjoys the evening…

— Daniel Wiffen (@WiffenDaniel) August 12, 2024

The 23-year-old Olympian swam in the polluted river during the men’s 10-kilometer event Friday. Wiffen came in 18th place in his first time swimming in an open-water event. Wiffen won gold in the men’s 800-meter freestyle and bronze in the 1500-meter freestyle, which takes place indoors.

“It’s probably one of the worst things I’ve ever done,” Wiffen told RTE after the event. “But, yeah, I’m happy I did it.”

Leading up to the Olympics, many raised concerns about the river’s history. Swimming in the Seine was prohibited for over a century due to its pollution, according to NBC News. Paris put forth a $1.5 billion effort to clean up the river in time for the Olympics. Officials continuously maintained that the water was safe despite concerns.

The water was rigorously tested for samples of E. coli, which, if the levels were high, would put those swimming in the river at risk for gastrointestinal illnesses, NBC reported.

Paris Mayor Anne Hidalgo swam in the river July 17 in an attempt to show the water was clean enough for the swimming competitions, according to The Associated Press (AP).

Hidalgo called out the spreading of “fake news” about the water’s quality on Aug. 6.

“There is absolutely no athlete who has been sick because they swam in the Seine River,” Hidalgo said. “The Seine River is de-polluted, and we are very proud and happy about that.”

Following her swim, she called the river “exquisite,” the AP reported. “The water is very, very good. A little cool, but not so bad,” she said.

Paris mayor swims in Seine to ease water quality concerns before Olympics #Paris2024 pic.twitter.com/ZJ9tvVEddm

— CGTN (@CGTNOfficial) July 18, 2024

“There is no doubt that the quality of water today is not up to par,” Paris region official Marc Guillaume, who joined the mayor’s swim, said in a press conference on June 21. Guillaume added he was “confident” the Olympic events would occur in the Seine.

Multiple athletes complained about the quality of the water after their events and expressed concerns about getting sick. Tyler Mislawchuk, an Olympics competitor, puked 10 times after competing in the Seine. (RELATED: Seine It Ain’t So: France May Pooh-Pooh Iconic Event For Disgusting Reason)

“The swim in the Seine was disgusting,” triathlete Rachel Klamer told RTL News.

“While swimming under the bridge, I felt and saw things that we shouldn’t think about too much,” Belgium’s Jolien Vermeylen told Metro after the triathlon. “The Seine has been dirty for a hundred years, so they can’t say that the safety of the athletes is a priority. That’s bullshit!”