A view into the Grand Canyon from the South Rim 10 July 2003 in Arizona. (Credit: ROBYN BECK/AFP/Getty Images)

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Grand Canyon National Park officials say they are investigating whether anyone was exposed to radiation at unsafe levels while samples of uranium ore sat in plastic buckets in a park research building.

National Park Service spokeswoman Vanessa Lacayo says the three 5-gallon buckets have been removed from the building that houses the park’s archives and artifacts. About 550 people tour the collections every year, mostly by appointment.

Lacayo said Tuesday the agency is working with Arizona health and workplace safety officials on the investigation.

The Arizona Republic cited the Grand Canyon’s safety director in saying the park did not warn workers or the public of the potential harm that existed for years.

Uranium can be harmful depending on the amount, how people interact with it and the exposure time.

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