Elsevier

Clinical Oncology

Volume 23, Issue 4, May 2011, Pages 251-260
Clinical Oncology

Overview
The Chernobyl Accident — An Epidemiological Perspective

https://doi.org/10.1016/j.clon.2011.01.510Get rights and content

Abstract

Twenty-five years have passed since radioactive releases from the Chernobyl nuclear accident led to the exposure of millions of people in Europe. Studies of affected populations have provided important new data on the links between radiation and cancer—particularly the risk of thyroid tumours from exposure to iodine isotopes—that are important not only for a fuller scientific understanding of radiation effects, but also for radiation protection. It is now well documented that children and adolescents exposed to radioiodines from Chernobyl fallout have a sizeable dose-related increase in thyroid cancer, with the risk greatest in those youngest at exposure and with a suggestion that deficiency in stable iodine may increase the risk. Data on thyroid cancer risks to other age groups are somewhat less definitive. In addition, there have been reported increases in incidence and mortality from non-thyroid cancers and non-cancer end points. Although some studies are difficult to interpret because of methodological limitations, recent investigations of Chernobyl clean-up workers (‘liquidators’) have provided evidence of increased risks of leukaemia and other haematological malignancies and of cataracts, and suggestions of an increase in the risk of cardiovascular diseases, following low doses and low dose rates of radiation. Further careful follow-up of these populations, including the establishment and long-term support of life-span study cohorts, could provide additional important information for the quantification of radiation risks and the protection of persons exposed to low doses of radiation.

Section snippets

Statement of Search Strategies Used and Sources of Information

This overview is based on a detailed review of international peer-reviewed literature published since the 2006 Chernobyl Forum Review [1], found using PubMed, Medline and ISI, as well as key papers published before that, and publications in press based on international collaborations in which the authors participated.

Radiation and thyroid cancer before the Chernobyl accident

Thyroid cancer, a rare malignancy of the endocrine system, was first linked to external radiation exposure in a 1969 study of atomic bomb survivors [3]. Although the incidence peaked 25 years after the bombings [4] and has declined over time, thyroid cancer risk continues to be significantly elevated in this cohort 60 years later [5]. Both the studies of atomic bomb survivors and of patients receiving external radiation therapy for a range of malignant and benign conditions show a linear

Non-cancer Effects

A number of non-cancer end points have been reported in populations exposed to radiation from the Chernobyl accident. These are reviewed in [1]. Few studies are available in which individual dose estimates have been reconstructed and hence interpretation of the results is complex. Of particular note are studies of cardiovascular diseases and of cataracts among liquidators, which may have important implications for radiation protection.

Thyroid Cancer

Unquestionably, the most significant scientific lesson learned from Chernobyl is that exposure to internal radiation in childhood and adolescence causes an increase in papillary thyroid cancer. The suggestion from early descriptive studies has been confirmed in analytical studies with estimated doses and data on confounding and modifying variables. Although there are some differences, the magnitude of the excess thyroid cancer risks and the findings for effect modification by age at exposure

Conclusions

Twenty-five years have passed since the Chernobyl accident led to the exposure of millions of people in Europe. Studies of populations exposed have provided significant new information on radiation risks, particularly in relation to thyroid tumours following exposure to iodine isotopes. Recent studies among Chernobyl liquidators have also provided evidence of increases in the risk of leukaemia and other haematological malignancies and of cataracts, and suggestions of increases in the risk of

Acknowledgements

This research was supported in part by the Intramural Research Program of the US National Cancer Institute, NIH, DHHS. The authors wish to acknowledge all the people in Europe—in particular in the most-affected states of Belarus, Russia and Ukraine—as well as in Japan and North America who have worked tirelessly in the last 25 years to evaluate the health impact of the Chernobyl accident and to draw lessons from this catastrophe to improve the health of the affected populations, to better

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