Risk of thyroid cancer in Ukrainian cleanup workers following the Chornobyl accident

IntroductionThe Chernobyl accident resulted in a considerable release of radioactivity to the atmosphere, particularly of Iodine-131 (131I), with the greatest contamination occurring in Belarus, Ukraine, and western part of Russia.Material and MethodsIncrease in thyroid cancer and other thyroid diseases incidence in population exposed to Chernobyl fallout in these counties was the major health effect of the accident. Therefore, a lot of attention was paid to the thyroid doses, mainly, the 131I intake during two months after the accident. This paper reviews thyroid doses, both the individual for the subjects of radiation epidemiological studies and population-average doses. Exposure to 131I intake and other exposure pathways to population of affected regions and the Chernobyl cleanup workers (liquidators) are considered.ResultsIndividual thyroid doses due to 131I intake varied up to 42 Gy and depended on the age of the person, the region where a person was exposed, and their cow’s milk consumption habits. Population-average thyroid doses among children of youngest age reached up to 0.75 Gy in the most contaminated area, the Gomel Oblast, in Belarus. Intake of 131I was the main pathway of exposure to the thyroid gland; its mean contribution to the thyroid dose in affected regions was more than 90%. The mean thyroid dose from inhalation of 131I for early Chernobyl cleanup workers was estimated to be 0.18 Gy. Individual thyroid doses due to different exposure pathways varied among 1,137 cleanup workers included in the epidemiological studies up to 9 Gy. Uncertainties associated with dose estimates, in terms of mean geometric standard deviation of individual stochastic doses, varied in range from 1.6 for doses based on individual-radiation measurements to 2.6 for “modelled” doses.ConclusionThe 131I was the most radiologically important radionuclide that resulted in radiation exposure to the thyroid gland and cause an increase in the of rate of thyroid cancer and other thyroid diseases in population exposed after the Chernobyl accident.

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Cancers after Chornobyl: From Epidemiology to Molecular Quantification

Cancers ◽

10.3390/cancers11091291 ◽

2019 ◽

Vol 11 (9) ◽

pp. 1291 ◽

Cited By ~ 1

Author(s):

Dimitry Bazyka ◽

Natalya Gudzenko ◽

Iryna Dyagil ◽

Iryna Ilienko ◽

David Belyi ◽

...

Keyword(s):

Thyroid Cancer ◽

Incidence Rates ◽

Lymphocytic Leukemia ◽

Telomere Maintenance ◽

Histone H2ax ◽

Frequent Mutations ◽

Cleanup Workers ◽

Radiation Medicine ◽

Thyroid Cancer Incidence ◽

Torch Infections

An overview and new data are presented from cancer studies of the most exposed groups of the population after the Chornobyl accident, performed at the National Research Center for Radiation Medicine (NRCRM). Incidence rates of solid cancers were analyzed for the 1990–2016 period in cleanup workers, evacuees, and the general population from the contaminated areas. In male cleanup workers, the significant increase in rates was demonstrated for cancers in total, leukemia, lymphoma, and thyroid cancer, as well as breast cancer rates were increased in females. Significantly elevated thyroid cancer incidence was identified in the male cleanup workers cohort (150,813) in 1986–2012 with an overall standardized incidence ratio (SIR) of 3.35 (95% CI: 2.91–3.80). A slight decrease in incidence rates was registered starting at 25 years after exposure. In total, 32 of 57 deaths in a group of cleanup workers with confirmed acute radiation syndrome (ARS) or not confirmed ARS (ARS NC) were due to blood malignancies or cancer. Molecular studies in cohort members included gene expression and polymorphism, FISH, relative telomere length, immunophenotype, micronuclei test, histone H2AX, and TORCH infections. Analysis of chronic lymphocytic leukemia (CLL) cases from the cohort showed more frequent mutations in telomere maintenance pathway genes as compared with unexposed CLL patients.

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