Keywords
radioactive iodine isotopes
thyroid gland
radiation risk
thyroid cancer
cohort study
Ukrainian- American Thyroid Project
How to Cite
Abstract
Abstract. As a result of the accident at the Chornobyl Nuclear Power Plant, a significant amount of radioactive substances was released into the environment. Radioactive iodine isotopes, mainly 131I, became the main dose-forming factor for the population, especially children and adolescents. To research the remote effects of irradiation at an early age within the framework of a classical prospective cohort study, with the participation of the State Institution «V.P. Komisarenko Institute of Endocrinology and Metabolism of the National Academy of Medical Scienses of Ukraine», in cooperation with National Cancer Institute of the United States two cohorts were created. The main UkrAm cohort (children and adolescents at the time of the accident) was formed in 1998-2000. The In Utero UkrAm cohort included individuals irradiated in utero (prenatally). It was first surveyed in 2002-2006. Both cohorts have been followed for over 25 and over 20 years, respectively. The epidemiological methods of cohort observation have varied over time, with periods of active screening alternating with periods of passive or combined observation of cohort members.
Objective: to describe the chronology of long-term (20-27 years) observation of the main and In Utero UkrAm cohorts, to characterize
various epidemiological procedures, to justify the need for further observation, and to determine the priority tasks of the study for the future.
Material and methods. During the observation period, the main cohort had four active screening examinations in the period from 1998 to 2008. The InUtero cohort, after the first examination (2002-2006), was observed passively in 2007-2008. Since 2009, the cohort observation has been synchronized. Passive screening is carried out through examinations at the IEM and cooperation (linkage of records) with the National Cancer Registry. The next active screening (fifth and second) was carried out in 2012-2015. Passive screening of cohorts was accompanied by a demographic questionnaire, which allowed updating contact details, certain medical information, and the vital status of cohort members.
Results. The recommendations of several expert groups are summarized: Agenda for Research on Chornobyl Health, IARC expert group, Expert Group on Thyroid Health Monitoring after Nuclear Accidents, and United Nations Scientific Committee on the Effects of Atomic Radiation experts on current results and priorities for prospective post-Chornobyl research. The need for further observation of the two UkrAm cohorts is substantiated and key areas of future research of the UkrAm Project are indicated. The need for further monitoring of two UkrAm cohorts is substantiated and key areas of future research of the UkrAm Project are indicated.
Conclusions: Based on long-term observations of the main and In Utero UkrAm cohorts (over 25 and over 20 years), fundamental results on the risk of thyroid cancer were obtained for individuals irradiated in childhood or prenatally. Continuing to observe these cohorts for a period of 40-60 years after the accident can fundamentally supplement the existing knowledge regarding the radiation risk of 131I exposure in the long term and improve radiation protection procedures for the most vulnerable population groups in the event of nuclear accidents.
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