Experts dispute Grand Canyon radiation threat

GRAND CANYON NATIONAL PARK, Ariz. – It’s no cause for alarm. That’s what some experts said about a Grand Canyon safety manager’s allegation that thousands of people may have been exposed to dangerous radiation for nearly two decades inside a National Park building.

At issue are three buckets of stones, believed to be uranium specimens, that were collected decades ago and stored from 2000 to 2018 in a museum collections building that was sometimes visited by tourists and students, as well as employees.

Elston “Swede” Stephenson, federal health and safety manager at the South Rim, recently fired off letters warning colleagues, members of Congress and media that untold numbers of people may have been endangered, yet National Park Service officials struck a “secrecy pact” and did not notify the public.

Stephenson based his assertion on radioactivity readings gathered by park officials, which appeared to be hundreds of times higher than thresholds set by the government for exposure.

The U.S. Occupational Safety and Health Administration and the Arizona Bureau of Radiation Control are investigating the matter with the Park Service, and have declined comment on Stephenson’s assertion. Instead, they say readings at the building – taken after the buckets’ contents were dumped into a defunct mine – show no danger.

As the controversy went viral this week, however, a number of experts declared that uranium ore is simply not a threat to humans, and questioned either the radiation readings taken by the Park Service or Stephenson’s interpretation of that data.

“It’s just a bucket of rocks,” declared Craig Little, a physicist who worked 25 years at the Oak Ridge National Laboratory and now serves as a consultant at uranium facilities. “I wouldn’t line my baby’s crib with it, but … ”

Little and Modi Wetzler, a chemistry professor at Clemson University who studies nuclear waste, said there are three types of radiation, and uranium ore emits only the least-dangerous rays, comprising gamma particles.

Wetzler said gamma rays are hazardous if inhaled or swallowed, but not externally dangerous because they can be absorbed and rendered harmless by a sheet of paper, a few inches of air, or a person’s outer layer of dead skin.

“The safety manager doesn’t know what he’s talking about,” Wetzler said.