Trial Information

Thyroid Abnormalities Associated With Protracted Childhood I-131 Exposure From Atmospheric Emissions From the Mayak Nuclear Plant in Russia

We plan to expand a completed pilot study that evaluated the prevalence of thyroid
abnormalities in relation to childhood exposure to atmospheric emissions of radioactive
iodines from the Mayak Nuclear Weapons Plant in Ozyorsk, Russia. The pilot study population
was composed of a defined cohort of approximately 900 Ozyorsk residents who were born
between January 1, 1952 and December 31, 1953. The exposed population was comprised of
persons who lived in Ozyorsk during the years of heavy atmospheric releases (1952-1953).
Members of the nonexposed group moved to Ozyorsk between 1967 and 1991, i.e. when there were
almost no radioactive releases. Results from the pilot study suggest an elevated prevalence
of thyroid nodules in the exposed population. Given the positive results from the pilot
study and the US Department of Energy's (DOE) decision to fund a dose reconstruction project
for the Ozyorsk population, we intend to expand the study to include an additional 350
people born and living in Ozyorsk between 1954 and 1955, i.e. exposed to moderate levels of
radiation .

Methods similar to those used in the pilot study will be used in the expanded study.
Members of the study population will be invited to participate in a special thyroid
screening protocol when they come for their annual routine medical examination at the
Ozyorsk automated dispensary system (ASDOC). The thyroid gland is clinically examined by
two ASDOC physicians specifically trained in thyroid palpation. Thyroid abnormalities will
be detected based on physical examinations, assessment of TSH levels, and ultrasound
imaging. Biochemical laboratory tests, including Free T(4), and anti-thyroperoxidase
antibodies will be assayed as necessary. Patients are sent to a consulting endocrinologist
if the palpation, ultrasound or laboratory findings suggest a thyroid disorder. Fine needle
aspiration (FNA) biopsy is performed when a tumor is suspected. Although the FNA is not be
done as part of the study research, but rather as part of the regular Ozyorsk medical
system, the results will be given to the study staff to help make diagnostic decisions.
Patients with complicated thyroid disease will be referred to an experienced consulting
thyroid specialist. Patients with diagnosed thyroid disease are treated within the regular
medical system in Ozyorsk.