An official has revealed that tourists who visited the Grand Canyon National Park in the past years might have been exposed to potentially unsafe levels of radiation, CNN reported on Wednesday.

Elston Stephenson, the park's safety, health and wellness manager, said that the Grand Canyon park museum had a stored uranium ore that caused the elevated levels of radiation around the area. 

He sent an email to all park staff in early February detailing the presence of radiation and their potential exposure. Stephenson said he made the announcement after officials from the National Park Service (NPS) and the Department of the Interior (DOI) ignored his request last summer to warn workers and tourists about the situation. 

Stephenson said in the email that visitors and employees who went to the Museum Collections Building between 2000 and June 18, 2018, were exposed to uranium. “By law we are supposed to tell you,” he stated. 

However, the park official noted that the exposure would not cause any health issue or contamination. DOI backed the claim, saying that to date the museum already has below levels of concern for public health and safety. 

Following Stephenson’s public announcement, NPS also started investigating the situation, as well as the Occupational Safety and Health Administration (OSHA), which recently sent inspectors to check the museum.

“The museum collection facility is open and employee work routines have continued as normal,” said Emily Davis, spokeswoman for the Grand Canyon National Park. “We will share additional information about this matter as the investigation continues.”

Stephenson said that he first found the buckets of uranium ore in June 2018 next to a taxidermy exhibit at the Grand Canyon museum. He believed that the materials had been at the facility for nearly two decades. He said he tried to encourage NPS officials for months to inform employees and the public about the possible uranium exposure. 

OSHA said it found that park service workers brought the buckets back to the park facility after dumping the uranium ore in the nearby Lost Orphan uranium mine. DOI's Office of the Inspector General announced on Tuesday that it will also investigate the issue.