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Japanese researchers have identified a cause-and-effect link between radiation from atomic bomb blasts and adult-onset thyroid cancer.
The new findings have reopened an old wound involving the controversy over atomic bomb tests in Nevada during the late ‘50s and early ‘60s.
Scientists from the Radiation Research Foundation in Hiroshima have been doing follow up studies on 120,000 atomic bomb survivors. Most survivors were very young when the bombs went off. From 1958 to 1998, researchers have identified about 470 thyroid cancers. If you put the raw numbers into a statistical yardstick, the excess cases triggered by radiation itself may be considered significant.
Adult-onset thyroid cancer takes a long time to form, so the Japanese are documenting the evolution over a 40-year period. Victims appear to have experienced a not-too-frequent adult mutation called chromosomal rearrangement, or RET/PTC.
Dr. Joseph Lyon of the University of Utah Public Health and Preventive Medicine said, "It looks to me now that it doesn't matter how you get it. If you're getting some form of radiation into that gland, it's causing damage, increasing the risk of cancer."
Dr. Lyon coordinated early research here, looking for a link among southern Utah residents exposed to fallout from open-air atomic bomb testing in Nevada. While victims in Hiroshima and Nagasaki were exposed to high-energy gamma, residents in southern Utah were exposed to radioiodine that was ingested in the food chain.
A meaningful statistical link to thyroid cancer itself was never proven to the satisfaction of government agencies funding the study. But Lyon says thyroid neoplasms, which are possible precursors to cancer, were identified in large numbers.
"[There was a] seven-fold increase, and it was dose dependent. Essentially as dose went up, thyroid neoplasms went right up. No question about it, it met all the requirements for statistically significant, if we put it in those terms," Lyon said.
Lyon believes the U.S. government simply did not want to know, so it cut off the money. Some of his colleagues don't agree.
In any case, Lyon's research group has submitted grant requests asking to continue long-term studies on residents in Russia exposed to radiation during the 1986 Chernobyl incident.
E-mail: eyeates@ksl.com
