Thorium in Coldwater Creek

from the Riverfront Times by C.D. Stelzer, 1997

Three thousand people live within a one-mile radius of the airport site, according to DOE estimates. From the airport, Coldwater Creek flows northeast for 15 miles, touching the communities of Berkeley, Hazelwood, Florissant and Black Jack before discharging into the Missouri River. The city of St. Louis drinking-water intakes at Chain of Rocks, which supply water to hundreds of thousands of people, are five miles downstream from where the Missouri joins the Mississippi.

By any standard it is a densely populated watershed. DOE guidelines for thorium and radium concentrations mandate they not exceed 5 picocuries per gram averaged over the first 15 centimeters of soil and 15 picocuries per gram in subsequent soil layers of the same thickness. Analysis conducted for DOE in 1985 indicates that soil next to Coldwater Creek is contaminated with as much as 14,000 picocuries of thorium-230 per gram. The naturally occurring background level for the same radioactive isotope amounts to 0.2 picocuries per gram.

The corresponding guideline for acceptable DOE levels of uranium-238, which is also found at the airport site, is 50 picocuries per gram. In 1981, DOE initiated a two-year groundwater-monitoring program at the site and discovered uranium-238 at concentrations up to 2,230 picocuries per gram. Other evidence shows radioactive waste is spread across the site at levels thousands of times greater than considered acceptable.

A curie is the amount of radiation emitted from one gram of radium, equal to 37 billion decays per second. A picocurie equals a trillionth of a curie. Curies are used to measure the amount of material present; they don’t indicate the amount of radiation given off or its biological hazards.

Such DOE standards ignore potential health consequences, according to a 1991 congressional study. “The present regulatory-driven approach … places far more emphasis on characterizing the contamination than on investigating health impacts and may prove ill-suited to identifying public health concerns, evaluating contamination scenarios according to their potential for adverse health effects, or establishing health-based clean-up priorities,” the Office of Technology Assessment report states.


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