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June 21, 2002
CDC Releases Hanford Thyroid Disease Study Final Report
Data Show Risks of Thyroid Disease About the Same Regardless of Radiation Dose from Hanford
Findings announced from the Hanford Thyroid Disease Study (HTDS) Final Report show that the risks of thyroid disease in study participants were about the same regardless of the radiation dose they received from radioactive iodine-131 from the Hanford Nuclear Weapons Production Facility in Washington State between 1944 and 1957. While thyroid disease was found, researchers determined that rates of the disease in the study participants were about the same as rates in other populations.
The Centers for Disease Control and Prevention (CDC) and the Fred Hutchinson Cancer Research Center released the findings of the 13-year study at a community meeting in Richland, Washington.
"We used the best scientific methods available, and we did not find an increased risk of thyroid disease in study participants from exposure to Hanford's iodine-131," said Paul Garbe, D.V.M, epidemiologist and CDC's scientific advisor for the study. "If there is an increased risk of thyroid disease, it is too small to observe."
The HTDS research team studied all types of thyroid diseases and examined how the rates varied in relation to participants' estimated radiation doses from Hanford's iodine-131.
"On the basis of a study population of 3,440 people, we found that people with higher doses of radiation had about the same amount of thyroid disease as people with lower doses," said Scott Davis, PhD, Fred Hutchinson's principal investigator for the HTDS. "We analyzed the data a number of ways, and the results were the same."
The research team also found that the rates of thyroid disease in the people who participated in the HTDS were generally consistent with the
rates of disease in other populations in the United States, based on a review of published scientific literature conducted after the release of
the HTDS Draft Report in 1999.
"Thyroid disease is fairly common in other populations across the country, especially among older people and women," Garbe said. "However, we understand the concern that people in the Hanford region have about thyroid disease, given their exposure to iodine-131, and we want to provide as much detail as possible about our findings and what they mean."
The HTDS focused on a group of people who were young children when they were exposed to iodine-131 from Hanford between 1944 and 1957.
Iodine-131 accounted for most of the radiation dose to the people exposed to Hanford's radiation. Scientists believe that young children receive
a higher dose to the thyroid gland than adolescents and adults for the same level of exposure and that the thyroid gland in young children may
be more sensitive to the effects of radiation.
Study participants had a wide range of possible doses to the thyroid gland, from very high to very low doses. This range enabled researchers
to compare groups of people who have similar characteristics (such as birth, diet and lifestyle) but different levels of exposure. This approach
of studying a single population comprising individuals with different levels of exposure has been used extensively in assessing the effects of
radiation exposure in human populations.
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This page last updated June 22, 2002
United States Department of Health and Human Services