Grand Canyon National Park.
For nearly 20 years, a trio of 5 gallon (19 liter) paint buckets sat near the taxidermy exhibit in the Grand Canyon National Park’s museum collections building. Those buckets, as it turns out, not holding paint they were actually loaded with uranium ore, a naturally occurring rock rich in uranium, that indicates a potentially hazardous radiation.
Elston “Swede” Stephenson, a health and wellness manager at the park’s South Rim, recently described uranium and the subsequent “cover-up” in a series of email blasts to the Congress, his colleague from the National Park Service employees and the employees of the Arizona Republic newspaper. [Soviets Hidden Nuclear Bunkers in the Polish Woods (Photos)]
Stephenson warned that thousands of workers, tourists and school classes who visit the exhibition between 2000 and 2018 were supposedly “exposed” to hazardous amounts of radiation, in particular for groups of children, who sat for the 30-minute presentations in the uranium in the environment. These children are exposed to about 1,400 times the safe dose of radiation permitted by Nuclear Regulatory Commission, Stephenson wrote. Scary stuff, if true.
However, a number of experts told the Science that Stephenson’s assessment may be unfounded.
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“As the time spent in the vicinity of the ore was too short, there is probably little to no reason for concern,” Bill Field, a professor of Occupational and Environmental Health at the University of Iowa, told Science in an e-mail.
Safe ore not safe?
Over time, uranium can break down in radioactive substances such as radium, and the release of harmful gases such as radon. Studies of uranium miners have shown that long-term exposure to uranium’s decay products can increase the chances of getting cancer — However, Field said: “The risks of a few buckets of uranium ore is quite different than a career in the uranium mining industry.”
According to F. Ward Whicker, a radioecology expert and emeritus professor at Colorado State University, uranium ore is primarily emits gamma particles — the least dangerous form of radiation.
“The amounts of the exposure to radiation from natural terrestrial sources and galactic cosmic rays to people everywhere is a lot higher than most realize,” Whicker told Science in an e-mail. “Life thrives in this constant radiation environment, because DNA repair mechanisms work efficiently and quickly in the cells — on the condition that the intensity of the exposure to radiation is within certain levels.”
The danger, if any, of the Grand Canyon ore buckets, depends on a long list of factors, Whicker said, including an individual away from the ore, the duration of the exposure, the quantity of the ore in the buckets, the amount of uranium in that ore, and the amount of shielding provided by the rocky parts of the ore itself and the packaging.
In this case, the plastic buckets of paint, provided a sufficiently powerful shield against the ore-radiation. Modi Wetzler, a professor of chemistry at Clemson University, a study of the nuclear waste, told The Arizona Republic that, while gamma radiation can be dangerous when inhaled, they are easily absorbed and made harmless by only a few inches of air, or even a person in the outer layer of dead skin.
The ore on the relative innocuousness is reflected in a report from the Parks Service, Stephenson referenced in his e-mails.
After a teenager with a Geiger counter accidentally discovered the ore buckets in the museum in March 2018, the national Parks Service will begin with a brief examination of the test radiation in and around the building. According to their report (which Stephenson noted to The Arizona Republic ), the direct contact with the ore resulted in radiation levels at about twice the safe annual dosage permitted by the Nuclear Regulatory Commission — however, the measurements are taken at only 5 ft (1.5 m) away from the bucket showed zero radiation.
The following steps
The uranium ore is now disposed of in a nearby uranium mine. Meanwhile, the Parks Service, the U. S. Occupational Safety and Health Administration and the Arizona Bureau of Radiation Control is now investigating the museum and grounds. According to Emily Davis, Grand Canyon National Park Public Affairs Officer, the radiation levels at the site are normal and safe.
“A recent study of the Grand Canyon National Park the collection of the museum facility and found radiation levels to background levels — the amount that is always present in the environment and under the level of care for the public health and safety,” Davis told NPR. “There is no current risk to the public or park employees. The collection of the museum facility is open and work continues as normal.”
The long-term effects caused by the ore’s 18-year stint in the museum remain to be identified. While it might be negligible, the ore probably did increase the radon in the building is somewhat Field, told Science.
“The basis must radon test carried out,” Field said. “In the long term, however, the potential exposure to radon from natural sources in the ground and the rocks under the facility would likely be the largest source of radiation exposure to the public and the employees.”
Stephenson did not immediately respond to Live Science’s request for comment.
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Originally published on Live Science.