Twenty years later, the April 1986 Chernobyl accident
lives on in different ways — in fact and fiction.
Today, national and international experts from eight United Nations agencies including the IAEA are working to sift fact from fiction. They are teamed with Belarus, Russia, and Ukraine to evaluate, document and report the accident’s true scale. Known as the Chernobyl Forum, the group issued its comprehensive report in September 2005. It covers health and environmental consequences, and includes recommendations to channel assistance to where it is most needed.
Dr. Fred Mettler is a member of the Forum, and a Chernobyl veteran researcher — he served as the health team leader in an IAEA-led international project that first presented on-site assessments of Chernobyl’s effects in the early 1990s, and participated in the International Chernobyl Conference in 1996 that summed up what was scientifically known then. In this essay, he revisits Chernobyl’s health picture from personal and professional perspectives.
When I first visited the highly contaminated areas in the late 1980s as part of the International Chernobyl Project, our work was primarily conducted in highly contaminated small rural villages. I was profoundly impressed by the devotion and concern about children (something much deeper than I had ever seen in the Western world).
The villagers had a very limited view of their geographic surrounding and often only knew villages within 30 kilometer radius. Many families had lived in the same village for hundreds of years and had not seen foreigners since World War II. The radioactive fallout was rapidly followed by forced relocation of hundreds of thousands, the rapid breakup of the Soviet Union, the collapse of infrastructure, the arrival of technology and access to mass media. All this permanently and adversely changed the lives, values and culture of the people.
Over the last 20 years there have been a number of scientific reports and estimates of the Chernobyl consequences. Certainly, in the first days of the accident there were uncertainties and confusion, but within a few months the levels and types of contamination were well known. Hundreds of thousands of workers (liquidators) were brought in to contain the situation. People in highly contaminated areas were relocated. Non-Governmental Organizations (NGO’s) and various governments (particularly Japan and European) responded with scientific programs. The Soviet government instituted extremely large health and social welfare programs.
Evaluation of the health effects of the accident has been subject to many limitations. Not the least include lack of reliable baseline health data for many diseases, incomplete reporting, variable diagnostic criteria and lack of evaluation of a radiation dose-response effect. The health effects data has been further complicated by the breakup of the Soviet registries and lack of sharing of data among institutions. The non-radiation related high infant mortality, high use of tobacco and rapid decline in average lifespan throughout the former Soviet Union have also confounded data analysis. For example, the average lifespan of males in Russia as a whole has dropped from about 70 years of age to 58 in the last decade often due to alcoholism or suicide.
Distressingly variable and unsubstantiated claims in the media over the last two decades have caused confusion, doubt and a persisting problem for not only those directly affected but also the rest of the world. In contrast, the scientific community has been rather consistent in its assessment. This is not surprising since there exists over 100 years of literature on the health effects of radiation. The current assessment of the Chernobyl Forum is not much different from those prepared by previous scientific forums including the 1990 International Chernobyl Project and the 1996 IAEA/UN/WHO “One Decade After” Chernobyl conference.
The accident released vast quantities of short-lived radioactive iodine over thousands of square kilometers. The radioiodine was subsequently concentrated in the thyroid gland of many persons primarily as a result of the grass-cow-milk ingestion pathway. A large increase in thyroid cancer has occurred among those who were children and adolescents at the time of the accident. There were about 4,000 radiation-related thyroid cancer cases as of the year 2000 and more are likely to occur in the future. The long term survival rate for thyroid cancer is usually about 90-95%. No definite radiation related increase has been found among those who were adults at the time of the accident.
For over 100 years it has been known that there is an increased risk of many types of cancer after radiation exposure. Several types of leukemia may occur within two to three years of exposure and the risk may persist for 20-plus years. Most solid cancers do not occur within ten years of exposure but the risk may persist for three to four decades.
In spite of most predictions, no definite radiation-related increase in leukemia or in cancers (other than thyroid) has been demonstrated to date in the population living in the Chernobyl area although a small increase has been found in a limited study of Russian liquidators. The lack of a detectable increase in cancer deaths among the general population does not mean that no cancer deaths have occurred or that there is no radiation-related risk.
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