Dust settles: LANL analysis cites natural causes for radioactivity in the environment

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By Roger Snodgrass

Española – Los Alamos National Laboratory Wednesday answered a citizens monitoring study from 2007 with its own analysis of off-site radioactivity in the neighborhood of the lab.

While confirming the validity of measurements taken by Marco Kaltofen of Boston Chemical Data for the watchdog Government Accountability Project last year, LANL scientist Michael McNaughton drew different conclusions.

McNaughton thanked Kaltofen for raising interesting and important questions about sources of radiation in the local environment and inside homes and offices. But McNaughton interpreted the data as indicating a predominance of radiation from natural rather than emissions from the laboratory.

In fact, he reported, more than 99 percent of the radioactivity comes from natural, not man-made radioactive material.

“Almost all the radioactivity in indoor dust is naturally occurring,” he said in his conclusions and while there are some emissions migrating through water pathways, airborne contamination from the laboratory is not measurable more than one mile outside Los Alamos County.

There are also large variabilities throughout the region to the extent that it is impossible to derive a single number for background.

One question Kaltofen said he wanted to delve into deeper, when he revisited the area last month, was how to trace the radiation back to its source.

McNaughton’s study began with the assumption that there were three possible sources of radiation in the local environment – natural radioactivity, residual fallout from open-air nuclear testing in the 1960s and radioactivity from nuclear weapons operations at LANL.

Revisiting the Los Alamos Monitor’s office on DP Road, confirmed radioactivity reported in the GAP study, and actually revealed somewhat larger concentrations than GAP. The concentrations came from all three sources, including plutonium 239, ascribed to processing activities at an old facility at the end of DP Road. The radioactivity is mostly natural and in very small amounts.

The LANL investigation found overall that less than 1 percent of the dose near the laboratory comes from global fallout and much less than 1 percent comes from LANL.

By far the largest portion, 48 percent, of the natural radiation comes from radon, a radioactive gas given off by decaying uranium deposits in the soil, McNaughton said.

He attributed another 19 percent of radiation exposure in the LANL vicinity to terrestrial radiation from radioactive potassium, thorium and uranium in the earth itself, 13 percent to cosmic radiation, 10 percent to medical and dental exposures, mostly x-rays, and 8 percent to potassium in bananas, food and ash.

Man-made products, building materials and smoke detectors, he said, amounted to 2 percent of the radiation exposure and LANL’s total contribution added up to only one-tenth of that, about the same as the .2 percent of the radiation dose that can be chalked up to global nuclear fallout.

Downwind residents from the laboratory, including residents of the Embudo Valley and Picuris Pueblo were especially alarmed by elevated readings in their communities from the Gap study and follow-up measurements by the New Mexico Environment Department.

McNaughton said there were two lines of evidence against concerns that LANL emissions were finding their way to the communities across the valley. One was that air monitoring programs have detected no contamination beyond one-mile from the laboratory. The other has to do with the identification of specific radionuclides with global fallout rather than the radionuclides that could be more closely identified with the lab.

McNaughton’s report was presented to a meeting of the Citizen’s Radiation Monitoring Group at Northern New Mexico College in Española.

While one of his conclusions was that there were no health risks from the LANL emissions, Taos resident Jeanne Green criticized the lack of information about cancer clusters that might shed additional light on contaminants.

LANL officials said there were other agencies that conducted those studies.

They answered another complaint, that the lab was not adequately prepared for monitoring emissions from another emergency like the Cerro Grande Fire, by referring to the emergency officials who have been involved in those preparations.

Ken Lagattuta, a retired LANL physicist and member of the Northern New Mexico Citizens Advisory Board said, “People are worried about things that haven’t happened or things that have happened that weren’t reported right.”