The Hanford Thyroid Disease Study (HTDS) was an epidemiological study designed to determine whether thyroid disease is increased among persons exposed to atmospheric releases of radioactive iodine-131 from the Hanford Nuclear Site between 1944 and 1957. The study was mandated by an act of Congress in 1988 (Senate Bill 2889) that directed the Centers for Disease Control and Prevention (CDC) to conduct a study of thyroid disease among persons living in proximity to the Hanford site during the releases. An investigative team at the Fred Hutchinson Cancer Research Center was awarded a contract by the CDC in September, 1989, to carry out the study.
The study was conducted as a follow-up (cohort) study. A total of 5199 individuals were selected by birth records from1940 through 1946 in seven eastern Washington counties surrounding the Hanford site to form a cohort for follow-up. A total of 4875 (93.8%) were located and their identities confirmed; 4350 (83.7%) living, and 525 (10.1%) deceased. Of those living, 3448 agreed to participate in the study and were evaluated for the presence or history of thyroid disease in a HTDS clinic. At the clinic each person underwent a personal interview regarding their residence and medical history, provided a blood sample for a number of diagnostic tests for thyroid diseases, received a thyroid ultrasound examination, and underwent a physical examination of the thyroid by two thyroid doctors, each examining the study participants independently of the other. For those found to have a clinically detectable thyroid nodule, permission was sought to conduct a fine needle aspiration biopsy. Prior to the clinic visit, an attempt was made to interview the participant's mother or other close relative regarding aspects of the participant's childhood that could have influenced the radiation dose received from Hanford, especially the source and amount of the milk they drank. This information was used to estimate an individual radiation dose to the thyroid for each study participant. The primary analysis of the study included thyroid abnormalities detected by ultrasound, results of seven laboratory assays, hyperparathyroidism and the following eleven categories of thyroid disease: a) Thyroid Carcinoma; b) Benign Thyroid Nodule; c) Any Thyroid Nodule; d) Hypothyroidism; e) Autoimmune (Hashimoto's) Thyroiditis; f) Grave's Disease; g) Autoimmune Thyroid Disease; h) Hyperthyroidism; i) Multinodular Thyroid Gland; j) Simple Goiter; k) Other or Unspecified Thyroid Disease.
The final report of the Hanford Thyroid Disease Study was made available on June 21, 2002. A committee of the National Academy of Sciences (NAS) reviewed a draft of the final report as well as how the draft results were communicated. The draft report issued in January 1999 drew substantial criticism from the National Academy of Sciences (NAS) and other scientists. In December 1999, the NAS issued the following report: http://books.nap.edu/books/0309068835/html/1.php.
The final report of the Hanford Thyroid Disease Study found no increase in risk for thyroid disease among those receiving the highest dose estimates from Hanford's iodine-131. "If there is an increased risk of thyroid disease, it is too small to observe."
Study scientists stressed that "the findings do not prove that Hanford radiation had no effect on the health of the area population," nor that any individual's disease was in fact not caused or contributed to by exposure to Hanford emissions.
Your attorneys asked five scientists to review the final report and evaluate whether the conclusions are reliable and supported by the data. Click here to view a copy of the experts' report on HTDS (.pdf format - requires Adobe Acrobat).
