The May 15 Post-Dispatch highlighted selected expert opinions that did not fairly present the risks and concerns about nuclear wastes in the Coldwater Creek watershed and the West Lake Landfill.
It was stated that the waste, thorium-230, a byproduct from purifying uranium, emits tiny amounts of gamma rays with most of the radiation coming from nonpenetrating alpha particles. What was omitted was that thorium preferentially attaches to soil particles, which can get inside the human body through inhalation. The alpha particles then produce ionizing radiation within the body that can have a latency effect of 20 years or more in causing cancer and other health problems. Thorium dust can occur any time this material is exposed to wind currents; it can be blown long distances. Alpha radiation sources are difficult both to locate and measure. Thorium alpha decay has a half life of more than 75,000 years.
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Gamma ray radiation exposure is dependent on the quantity of daughter products present from the radioactive decay of thorium, the distance a person is from the waste and the exposure time. Most scientific knowledge of health effects of gamma radiation is drawn from the study of Hiroshima bomb victims. “Safe†radiation limits were estimated using a dose rate factor to allow higher limits than a linear model, as it was assumed that a higher dose rate would cause more cancers than the same total dose received in lesser amounts over a longer period of time. A recent study of 300,000 radiation monitored workers (Leuraud et al., Lancet Haematology) found that risks do not depend on dose rate. This study supports equivalent cancer risk for long-term exposure to low dose rate radiation, and thereby calls into question clean-up criteria using only dose rate factors. The monitored workers have given a better measure of actual dosage and its relationship to cancers than the quoted report, which estimates radiation from environmental factors.
The radiation concern for Coldwater Creek arises from outdoor, open storage of nuclear waste next to the creek, allowing random waste distribution throughout the entire watershed from flooding and residential construction for 20-plus years. It is critical to expedite the investigation and remediation of all areas where floods have occurred or where it was known that the creek was rerouted. Also needed is the complete removal of the concentrated dumped Coldwater Creek wastes at West Lake Landfill. Health care for all injured by radioactive waste should be paid by the U.S. government.
John Rodden • Weldon Spring
