leroymoore

FACT SHEET: Risk from Plutonium in the Environment at Rocky Flats

In Environment, Plutonium, Public Health, Rocky Flats, Wildlife Refuge on January 16, 2011 at 8:31 am

Toxicity: “Plutonium is fiendishly toxic, even in small amounts” (Glenn Seaborg, who isolated and named plutonium in 1941, quoted in Jeremy Bernstein, Plutonium [2007], p. 105).

Long-term danger: Plutonium 239, the material of principal concern at Rocky Flats, has a half-life of 24,110 years. It remains dangerously radioactive for more than a quarter-of-a-million years. Tiny particles left in the environment pose an essentially permanent danger.

Lethal quality of internalized plutonium: The alpha radiation emitted by plutonium cannot penetrate skin like gamma radiation or x-rays. But tiny particles inhaled, ingested, or taken into the body through an open wound may lodge in the lungs or migrate to the liver or to the surface or marrow of bone. For as long as it resides in the body it continues to bombard surrounding tissue with radiation. The result may be cancer, genetic defects, harm to the immune system. The latent period for cancer is likely to be 20 to 30 years.

Plutonium particle in lung tissue: “The black star in the middle of this picture shows the tracks made by alpha rays emitted from a particle of plutonium-239 in the lung tissue of an ape. The alpha rays do not travel very far, but once inside the body, they can penetrate more than 10,000 cells within their range. This set of alpha tracks (magnified 500 times) occurred over a 48-hour period” (Robert Del Tredici, At Work in the Fields of the Bomb [1987], plate 39).

Dangerous in very small amounts: Plutonium particles of 10 or less microns can be inhaled. The average diameter of human hair is about 50 microns. Meteorologist W. Gale Biggs concluded that most airborne particles at Rocky Flats were probably smaller than 0.01 microns (“Emissions and Monitoring of Plutonium from Rocky Flats,” April 26, 2007).

More harmful than other forms of radiation: Internal alpha emitters like plutonium are much more harmful per unit dose than penetrating gamma or x-ray radiation. To account for the difference, the International Commission on Radiological Protection refers to the “relative biological effectiveness” (RBE) of alpha emitters. Looking at the potential harm to different organs and for different disease end-points, ICRP concludes that the average RBE for alpha emitters is 20. This means that, on average, internal alpha emitters are 20 times more harmful than penetrating radiation of the same dose. But because 20 is an average, for some body organs and certain cancers as well as for particular individuals the actual RBE can be higher, sometimes much higher. For example, the RBE for bone cancer ranges as high as 320. (On RBE for plutonium, see Helen A. Grogan et al, Assessing Risk of Exposure to Plutonium, Feb. 2000 [Risk Assessment Corporation], pp. 6.27-6.39)

Incautious approach used in setting Rocky Flats cleanup standards: Those who set the cleanup standards for Rocky Flats followed the ICRP in using 20 as the RBE for plutonium. This averaging approach disregards the harm that may result from plutonium exposure to certain organs of the body or to given individuals; it does not protect the most vulnerable members of the population. The Rocky Flats Cleanup Agreement allows 50 picocuries of plutonium per gram of soil to remain in surface soil after “cleanup,” much larger quantities of plutonium at levels below three feet. Doubling the plutonium RBE to 40 would reduce the 50 picocuries allowed in surface soil to 25; each RBE doubling would reduce by half the amount of plutonium allowed in the surface soil.

Potential harm to the human gene pool: A British research team concluded that the RBE for chromosomal damage from plutonium exposure is essentially “infinite,” because the extent of harm to the human gene pool is incalculable (M. A. Khadim et al, Nature, vol. 355, no. 20 [Feb. 1992], pp. 738-740). The resultant “genomic instability” may account for illnesses other than cancer, illnesses so elusive that epidemiology is “powerless” to detect any relationship between their incidence and exposure to radiation (Rob Edwards, New Scientist, vol. 11, Oct. 1997, pp. 37-40).

Harm from a single particle: Tom K. Hei and colleagues at Columbia University demonstrated that a single plutonium alpha particle induces mutations in mammal cells. Cells receiving very low doses were more likely to be damaged than destroyed. Replication of these damaged cells constitutes genetic harm, and more such harm per unit dose occurs at very low doses than would occur with higher dose exposures. “These data provide direct evidence that a single alpha particle traversing a nucleus will have a high probability of resulting in a mutation and highlight the need for radiation protection at low doses.” In a follow-up study, they found that “a single alpha particle can induce mutations and chromosome aberrations in [adjacent] cells that received no direct radiation exposure to their DNA” (Proceedings of the National Academy of Sciences, vol. 94 [Apr. 1997], pp. 3765-3770; and vol. 98 [4 Dec. 2001], pp. 14410-14415).

Current radiation standards inadequate: The Committee Examining Radiation Risks of Internal Emitters, consisting of British government and independent scientists, concluded in 2004 that cancer risk from very low-doses of plutonium may be ten or more times more dangerous than allowed for by existing exposure standards. Among other adverse effects, the cellular descendants of seemingly unharmed exposed cells can suffer delayed damage (http://www.cerrie.org/).

Excess cancers among Rocky Flats workers exposed to purportedly safe levels: In 1987 Gregg S. Wilkinson of DOE’s Los Alamos Lab published results of his study showing that some exposed Rocky Flats workers with internal plutonium deposits as low as 5% of DOE’s purportedly safe permissible lifetime body burden developed a variety of cancers in excess of what was normal for workers who had not been exposed (American Journal of Epidemiology, vol. 125, no. 2 [1987], pp. 231-250).

“Genetic uncertainty problem” for wildlife: Genetic specialist Diethard Tautz says that effects of radiation exposure on a given species of wildlife may not be readily apparent in individuals of that species until the passage of several generations. He calls this a “genetic uncertainty problem” (Trends in Genetics, vol. 16 [Nov. 2000], pp. 475-477). This finding suggests that wildlife at Rocky Flats could in the long-term be hurt by conditions at the site.

All the Rocky Flats site contaminated: Historically, while some areas at Rocky Flats were more heavily contaminated than others, plutonium particles released in fires, accidents, and routine operations were laid down across the whole of the site. This conclusion is supported by soil sampling done at predominantly upwind locations by F. Ward Whicker of Colorado State University and Harvey Nichols of the University of Colorado.

Extent of contamination unknown, cleanup inadequate: The government agencies responsible for cleanup of Rocky Flats never thoroughly “characterized” the Rocky Flats site to determine the full extent of contamination in the environment. They knowingly did not clean the site to the maximum extent possible. An unknown quantity of plutonium and other toxins remain in the environment.

Harmful form of plutonium left behind: Plutonium left in the Rocky Flats environment is in the form of very fine particles that can be inhaled or ingested. Buried plutonium can be brought to the surface most especially by the actions of burrowing animals that dig down to as much as 16 to 20 feet below the surface and are constantly moving soil and its contents. Plutonium particles brought to the surface can be picked up by wind and moved to other locations near and far. There is no guarantee that plutonium left in the Rocky Flats environment will remain safely in place or even on the site.

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  1. [...] Originally Posted by desertgem [/COLOR][/LEFT] http://www.nrc.gov/reading-rm/doc-co…plutonium.html Actually, being a strong alpha emitter, it does pose radioactivity danger, but the biological toxicity has been over stated. The worse seems to be by wound contamination, but its high water insolubility as an oxide and molecular weight makes it very difficult to be absorbed through ingestion. Not arguing that is is harmless, far from it, but being alpha emitter, shielding is rather easy compared to gamma or other radiation. breathing in particles poses a danger http://leroymoore.wordpress.com/2011…t-rocky-flats/ [...]

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