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Hanford's fallout: increased thyroid risks.

Hanford's fallout: Increased thyroid risks

Unbeknownst to the public, nuclear weapons production at the Hanford Nuclear Site in Washington emitted measurable quantities of radioactive isotopes into the air and water for decades. Now, a federally funded study estimates that up to 5 percent of the people who lived in a 10-county area surrounding the complex shortly after it opened in 1944 -- a time when Hanford's stack emissions went largely uncontrolled--may have received significant radiation doses. Most of this radiation arrived in milk from cows grazing on contaminated pastures, so small children probably received the highest exposures, the report's authors say.

Though preliminary, the dose estimates "are large enough to justify investigating the effects of radiation from Hanford on thyroid disease in the surrounding population," says John E. Till, a consultant based in Neeses, S.C. And indeed, the Centers for Disease Control plans to initiate such a study next year, says Till, who chairs a federally funded but independent panel of technical experts managing the Hanford Environmental Dose Reconstruction Project. The new report completes the first phase of that five-year project.

Until four years ago, the federal government "kept the lid on" data describing Hanford's radioactive emissions, says Jim Thomas, a staff researcher with the Hanford Education Action League, a citizen's group in Spokane, Wash. Responding to public pressure, the Energy Department publicly released some 19,000 pages of documents on Hanford operations to area libraries in February 1986. Those documents "showed that over the first 10 years of its operations, Hanford released more than 530,000 curies of iodine-131," Thomas says.

Dissolving reactor fuel in acid to extract plutonium caused the release of volatile iodine-131. And when Hanford first opened, any iodine that volatilized went right out the plant's smokestacks, because "there weren't filters on these stacks," says Angela Beers, a staffer for Till's panel. The new report attributes most offsite radiation exposures to short-lived iodine-131 emitted during the first few years of the facility's operations -- before pollution control's and process changes cut emissions dramatically.

Researchers at Battelle Pacific Northwest Laboratory in Richland, Wash., which operates the Hanford site, developed the new dose estimates by analyzing the likely dispersion of iodine-131 and other radioisotopes.

Between 1944 and 1947, milk contaminated with iodine-131 may have delivered doses exceeding 33 rem to the thyroids of as many as 13,500 area residents, the report states. Indeed, it says, some 4,000 people drinking milk from cows grazing downwind of Handford may have accumulated more than 100 rem, and a few may have received more than 2,500 rem.

During diagnostic procedures, endocrinologists have delivered iodine-131 doses of 50 to 100 rem to the thyroids of millions of patients, and "there is no evidence that that has ever caused any problems," observes David V. Becker, director of nuclear medicine at New York (City) Hospital-Cornell Medical Center. Cancers have been linked to higher doses, but such tumors tend to arise within 40 years of exposure. The message for people who lived near Hanford during the 1940s, Becker says, it that "if nothing has happened by now, it probably won't."

Over the next few years, Battelle researchers will refine their dose-reconstruction model. Their goal is a computer system that can generate individual dose estimates for residents based on where and when they lived in the area as well as their patterns of dairy-product consumption. Eventually, the system's designers also hope to tailor it to yield similar individualized chemical-exposure estimates for residents downwind of other polluting facilities.
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Title Annotation:Hanford Nuclear Site, Washington
Author:Raloff, Janet
Publication:Science News
Date:Jul 21, 1990
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