Health concerns have emerged at the Paris Olympics after three German swimmers fell ill following their participation in open water races held in the Seine River. The athletes, who experienced symptoms such as vomiting and diarrhea, have since recovered, but their illnesses have reignited fears about the safety of swimming in the historically polluted river.

The German Olympic Sports Confederation confirmed that three of its athletes were affected, with two female swimmers treated as outpatients on Friday and another swimmer still under medical observation. Although the confederation did not officially identify the athletes, Leonie Beck, who finished ninth in the women’s 10-kilometer race, shared her experience on social media. Beck posted a photo on Instagram, revealing that she had vomited multiple times and sarcastically commented on the water quality in the Seine.

The Seine River, a landmark of Paris, was chosen as the venue for the Olympic open water swimming events after extensive efforts to clean up its notoriously polluted waters. Swimming in the river had been banned for over 100 years due to high levels of bacteria, prompting a major and expensive cleanup operation ahead of the Olympics. Despite these efforts, concerns about the river’s safety persisted, particularly after some water quality readings before the events showed levels of harmful bacteria that exceeded acceptable limits.

Paris organizers and World Aquatics, the governing body for open water swimming, released testing data indicating that the water quality on the day of the race was within safe limits. However, the illnesses among the German swimmers have raised questions about whether those standards were adequate to protect the athletes’ health.

The Paris organizing committee issued a statement expressing concern for the affected athletes but emphasized that there was no confirmed link between their illnesses and the water quality in the Seine. “Water quality on the day of the marathon was considered ‘very good’ or ‘excellent’ across all four testing points,” the statement said.

The illnesses reported by the German swimmers have added to the controversy surrounding the use of the Seine as a venue for Olympic events. Earlier in the games, several triathletes also fell ill after competing in the river, though no direct connection to the water was established.