Uranium toxicity in question

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By The Staff

In the April 20, 2010 Monitor, the Sierra Club’s Mark Jones writes that renewed interest in uranium mining will benefit local economies but at a severe price.  He enumerates a list of the health effects, the tardiness of uranium tailings remediation, the modeling of exposure to residual uranium tailings as a predictor of diabetes and kidney disease, groundwater contamination and the burden to the taxpayer. He then turns to the coal companies to criticize mine safety. The first uranium boom was driven by the requirements for nuclear weapons — nuclear energy generation came later.   

We have no stock in uranium mining companies but we do actively support nuclear power generation as the most practical solution to the projected energy shortfall and we strongly disagree with the Sierra Club on the presentation of not-quite-accurate implications that sleight nuclear energy development. Hence, we attempt to provide some perspective on the health effects of uranium mining — there are no assertions, only facts that can be documented.  

Pooled data from a 1995 study on total cancer deaths from hard rock mining in the U.S., China, Czechoslovakia, Canada, Sweden, Australia and France, showed that 1.2 million person with years of underground exposure resulted in 2,701 cancer deaths of which 363 occurred in New Mexico, Arizona, Colorado and Utah. Investigators discovered that exposure to alpha particles from the decay daughters of radon-222 in poorly ventilated underground mine chambers caused the cancers. The cohort of deaths including a large number of Navajo men occurred in miners who spent significant time underground during the period before 1970. Beyond the 363 tragic deaths, most from radon-induced small cell carcinoma of the lung, there have been no demonstrable excess health effects despite intense epidemiological surveillance for uranium-induced disease. Radon abatement measures have eliminated the risk of significant new occupational or environmental radon exposures and with modern solution mining techniques, radon is not an issue.

The chemical toxicity of uranium is about the same as lead with similar tissue targets and evidence of injury or malignant disease from aboveground exposures to uranium tailings is not convincing. Studies of above ground workers and associated populations without a significant history of time underground, do not exhibit the hallmark cancer, the principal tragedy of the early boom. The reason is because the external radiation doses are small and high concentrations of radon-222 are not confined, as they are underground.  Radon-222 is a noble gas that escapes unless contained but the charged decay daughters attach to dust particles and “hitch hike” into the lungs. Without high concentrations of radon, fewer radon decay daughters become trapped in the lungs and excess cancers fail to develop.  It’s as simple as that.

 For 50 years, mill tailings cleanup has been a favorite topic whenever nuclear enterprise is taken to task. Tailings are the leftovers after the uranium has been extracted from crushed ore and although radioactive, largely because of residual radium-226, tailings have not caused the devastating health and environmental impacts some have predicted. With approximately 50 years of potential exposure, the tailings have been around long enough to cause excess cancers — they have not. Uncovered tailings exposures range from 15 to 30 mR/day (milliroentgens per day). A foot of soil covering reduces the exposure to about 3 mR/day and two feet of soil covering reduces the exposure to background. Groundwater contamination is site specific but catastrophic consequences to health, although alleged in hundreds of articles and reports, have not been demonstrated. The Church Rock holding pond breach with downstream Rio Puerco contamination is the prime example — tailings simply are not very radioactive, but gamma ray detection is incredibly sensitive.

The communities in the Grants mining district have been living with tailings and groundwater problems for 60 years — more than enough time for the appearance of maladies in excess of general population frequency. No recent clinical reports of such findings appear in medical literature. Although the hazard has changed with time, dire health assertions based on early experience remain the principal argument of uranium mining opponents — facts do not support the implications of the Sierra Club piece.