EDITOR’S NOTE: This is the third in a series on radioactive material generated by natural gas production in the Barnett Shale.

 

From the cosmic rays that bombard Earth, to the X-ray in the dentist’s office, to the Brazil nuts in the party mix, people are exposed to varying levels of radioactivity every day.

A century after the radiation poisoning deaths of Marie Curie and Clarence Dally, one of Thomas Edison’s assistants, re­sear­chers are still examining how much exposure humans can tolerate, according to Dr. Evan Douple, a researcher with the Na­tional Academy of Sciences and a leader in many of its respected series of reports, Bio­logical Effects of Ionizing Radiation.

Scientists also are still identifying where that exposure can come from.

Until recently, researchers didn’t know that oil and gas mining could concentrate naturally occurring radioactive material, or NORM. Geologists accidentally discovered elevated readings of radioactivity while flying over an oil field in the late 1970s, according to James Otton, a geologist with the U.S. Geological Survey.

Experts have since learned that NORM accumulation is less common in natural gas fields than oil fields, but the Barnett Shale is different. Two decontamination companies have cleaned up 25 Barnett Shale sites of about 1,000 barrels of radioactive waste in the past two years. Two of the nearly 200 operators registered with the Texas Railroad Commission to work in the Barnett Shale have provided for cleanup of the hottest waste.

Since discovering the problem and identifying some of the worst contaminations in the 1980s and 1990s, the petroleum industry and the agencies that regulate it have struck an awkward balance because low levels of NORM pose little risk to the environment and human health.

But, from time to time, oil and gas mining can also concentrate NORM so intensely that it generates readings as high as low-level uranium mining.

Licensed decontamination specialists recommend that energy companies regularly survey their equipment for NORM.

Once in proximity of NORM, humans and other living beings can be affected two ways, Douple said.

“If there’s radium lying on the ground, it gives off gamma rays,” Douple said. “That gives a whole body dose.”

But unless the NORM was exceptionally hot, a person would have to stand next to it, unprotected, for a very long time to receive a harmful dose, according to Tom Gesell of the Health Physics Society.

However, people and other living beings can also inhale or ingest isotopes that migrate from the site, either through the air, soil or water.

At that point, a person’s exposure risk depends on which isotope is ingested, Douple said.  

“Some people think ingesting isn’t such a big deal” because of nuclear medicine, he said. “But in the poisoning of that Russian spy [Alexander Litvinenko], by picking an isotope with a long biological half-life, they delivered a high dose.”

Litvinenko was likely given polonium-210, but radon gas is another such isotope that stays in the body, Douple said. Radon is part of the decay chain of radium-226 and radium-228, the two most common isotopes in oil and gas NORM.

Once radon is inhaled, “all of that energy is deposited right there in the lung tissue,” Douple said.

Radon is the second leading cause of lung cancer, according to the American Cancer Society. The colorless, odorless radioactive gas can become concentrated in homes and buildings, especially when they are built over NORM-contaminated soils. It can also travel in pipelines with the natural gas.

If environmental standards for NORM are reasonably protective, the public is less at risk, Douple said. Industry workers can be exposed to more NORM than the public, but only when the workers know how much they have been exposed to.

Fellow National Academy of Sciences researcher, John Wiley, who has direct experience with measuring and disposing of NORM, said oil and gas industry workers “should wear radiation badges [simple monitoring devices] just like radiation workers always wear their badges.”

After trouble spots are identified, the material should be cleaned and disposed of properly, Wiley said.

“Basically, in any kind of waste business, you want to put it in a pile where you can watch it,” he said.

PEGGY HEINKEL-WOLFE can be reached at 940-566-6881. Her e-mail address is pheinkel-wolfe@dentonrc.com .