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April 26, 1996
CHERNOBYL AND THE WORLD'S RESPONSIBILTYFriday, April 26, 1996, was the tenth anniversary of the terrible explosion at the Chernobyl nuclear power plant in the Northern Ukraine. The blast sent 50 tons of radioactive dust into an area of nearly 140,000 square miles - covering parts of the Ukraine, Belarus and Russia - and spread 200 times more radioactivity than the Atom bombs dropped on Hiroshima and Nagasaki combined.
It is estimated that as many as 4.9 million people have been exposed to significant doses of radiation. Thyroid cancer is appearing in large numbers of children who were under 18 at the time of the explosion, and instances of leukemia, cardiac problems and reproductive disorders are being tracked by scientists.
Dr. Elaine Gallin is Deputy Director of the Office of International Health Studies at the U.S. Department of Energy. Dr. Gallin's office sponsors and manages health studies investigating the effects of the Chernobyl accident. The Office staff combined to answer your questions about the aftermath of the Chernobyl explosion.
A question from Trynne Miller of Pomona, CA:I've heard that the patterns of illness in people in the affected areas around Chernobyl are markedly different than those that appeared in the survivors of Hiroshima and Nagasaki. Is this true and why?
The Office of International Health Studies responds:
Since the Chernobyl accident, health effects on the exposed populations have been the focus of numerous epidemiological studies. It is now clear that the accident has resulted in a large increase in the incidence of childhood thyroid cancer and also has produced negative psychological effects. Data on other health effects that are directly the result of the accident have been either negative or inconclusive.
These results differ from the data on the A-bomb survivors from Hiroshima and Nagasaki (the most complete data that the world has on the health effects of exposure to ionizing radiation). The level of radiation-induced thyroid cancer was lower and the latency period was longer in the A-bomb survivors than in the Chernobyl populations that have been studied. Furthermore, a significant increase in leukemia was evident in the Japanese survivors during the first ten years after the detonation of the A-bombs. In contrast, three major international studies examining the incidence of leukemia in exposed populations following the Chernobyl accident have reported no detectable increase in leukemia at this time.
The much higher rates of childhood thyroid cancer in populations exposed because of the Chernobyl accident compared to the A-bomb survivors can be explained by the fact that the Chernobyl accident released large quantities of radioactive iodine which was internalized, while the detonation of the A bombs resulted in a short burst of external neutron and gamma irradiation. Ingested and inhaled radioiodine are preferentially incorporated into the thyroid gland and can result in high levels of exposure to the thyroid gland compared to the rest of the body.
The reason for the lack of increase in the incidence of leukemia in the exposed populations ten years after the Chernobyl accident is less clear. One possible explanation may be the fact that the Chernobyl population have experienced chronic radiation exposure in contrast to the A-bomb survivors who experienced an acute high dose rate radiation exposure. Another possible explanation may be the difficulty in detecting small changes in the number of leukemia cases. Leukemia is a rare disease. The number of leukemia-induced radiation deaths predicted following Chernobyl (predicted from models derived from the A-bomb survivors) would be quite small, estimated to be on the order of 200 in 3.7 million residents of contaminated areas.
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A question from Sean Wargo of Boston, MA:
A recent op-ed article in the Washington Post suggested that up to thirty million people are drinking water from contaminated rivers. What are the potential long-term affects of this?
The Office of International Health Studies responds:
Human exposure through the drinking-water was mainly a concern during the initial fallout phase of the accident, but could become a problem in the future if the contamination is washed out from the catchment areas and reaches drinking water supplies.
In the initial year after the Chernobyl accident, environmental measurements of radioactive contaminant levels were taken from several of the rivers and reservoirs in the areas surrounding Chernobyl. The Nuclear Energy Agency determined radioactive contaminant levels the during the initial year after the accident were 10kBq/L in the river Pripyat, 5kBq/L in the Uzh river and 4kBq/L in the Dnieper. Calculations of doses to the public from drinking water from rivers and reservoirs at these levels of contamination were determined not to be a public health concern. The doses from drinking water intake received by the public the initial year after the Chernobyl Accident were found to be under the Environmental Protection Agencies (EPA) recommended yearly allowable dose for a member of the public of 100mRem. The dose to the public has continued to decrease as the levels decrease due to the natural decay of the radioactive contaminants.
Nevertheless, the consensus view is that monitoring will need to be continued to ensure that future washout from the catchment area which contains a large quantity of stored radioactive waste will not contaminate the drinking water.
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A question from Chad Ford of Fargo, ND:
What does it mean that the main health problem following Chernobyl is Thyroid disease in children. How many are stricken, what are the life expectancies of these people, what are the affects of this cancer, can they live active lives? Is this a treatable kind of cancer?
The Office of International Health Studies responds:
Childhood thyroid cancer is normally a very rare disease that occurs at a rate of about one to a few cases per million children a year. The treatment for this cancer consists of a surgical removal of thyroid gland and a life long, daily replacement, with thyroid hormone. In such cases the life expectancy of the affected children as adults is greater than 95% with no impairment in the quality of life.
Previous studies of populations medically or accidentally exposed to irradiation concluded that exposure of thyroid gland produces appreciable risk of thyroid cancer. The increase in the incidence of childhood thyroid cancer was therefore one of the anticipated outcomes of the Chernobyl accident. What was not anticipated was the very early increase in the childhood thyroid cancer cases, within 3 to 4 years instead of anticipated 5 to 10, and the magnitude of this increase that greatly exceeds the anticipated. For example, in Belarus from 40 to 120 cases of childhood thyroid cancer were anticipated to occur in first 10 years after the accident. Instead over 400 cases were observed. Similarly, in Ukraine a very substantial increase in these cancer have been reported, with a total of about 500 cases.
In terms of the mortality from childhood thyroid cancer associated with the Chernobyl accident, only 3 deaths were reported. The low mortality is probably due to the early detection thanks to a very intensive surveillance of the thyroid gland in the children in the contaminated Chernobyl regions. It is expected that the treatment of the affected children with the thyroid hormones should not reduce their life expectancy. The proper medical monitoring of such children should also allow for their leading productive and active lives, as in the case of the childhood thyroid cancer cases in the Western countries.
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A question from Amy Shuster of Washington, DC:
The news from that part of the world is rarely good on the economic or any other front. Can whatever's left of the medical system over there do enough to help the huge numbers of people who've been bombarded with radioactivity? What is the United States doing to help, or the west for that matter? Can we do any more to help or is it simply to large a problem to expect to be able achieve any positive results.
The Office of International Health Studies responds:
This question has been answered in two parts:
1) the adequacy of the medical system in the countries of the Former Soviet Union in taking care of the populations; and
2) the involvement of the Western countries in helping to assure adequate medical care to those exposed.
In response to the first question, there is an established infrastructure of hospitals and dispensaries in the countries of the Former Soviet Union staffed with dedicated physicians. However, because of the economic difficulties, which were exacerbated by greatly increased numbers of individuals in need of treatment for actual or perceived, stress-induced problems, it has become very difficult for the local physicians to provide adequate care. In addition, the general is that medical equipment and training have not been up to par with western medicine and requirements for diagnosis and treatment.
Regarding the second question, the scientists and physicians from the United States, Japan, and western European countries are working together with the local hospitals and dispensaries to advise and help in diagnosis and medical care, and to provide equipment and supplies necessary to treat the local patients. This experience benefits not only the local communities but also the international scientific and medical community, through developing a better understanding of effective care and treatment for the populations experiencing effects of extensive radioactive pollution. Lessons learned in the first ten years following the disaster indicate that the clinical dimensions of the problem may be less serious than originally expected. Instead, one of the major problems appears to be socio-economical and stress-associated. Furthermore, the magnitude of these problems is such that it is important that the whole international community works together to mitigate them.
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A question from George Felcyn, Anchorage, AK:
I've seen maps of how the radiation spread that have it going far into the Arctic, Scandinavia and all over Europe. What health problems have been seen outside the former Soviet Union? Was Alaska affected at all?
The Office of International Health Studies responds:
The doses of radiation to the populations in various countries of the northern hemisphere caused by the accident have been assessed by a United Nations committee (UNSCEAR). This committee estimated individual doses outside the former Soviet Union, e.g., the highest national average first year dose was 0.8 millisieverts. To put this number in perspective, the global annual average radiation dose from natural background is 2.4 millisieverts, with considerable geographic variation. No health problems have been observed thus far from this small increase in radiation over natural background levels. Where appropriate, local populations in Nordic countries have been advised concerning excessive consumption of foods that may still contain radionuclides of health concern, such as radiocesium. With regard to Alaska, there are ongoing programs related to the safety of local food resources in Alaska, although there is no major contamination of the marine ecosystem. Almost all radiocesium contamination in Alaska originated from global nuclear weapons testing in the 1960's and with diminished atmospheric nuclear weapons testing this contamination continues to decline.
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A question from Joseph McDonald of Burlington, VT:
At some point the nations of the former Soviet Union have to take responsibility for their own actions. These nations will have no motivation to improve their systems and infrastructure if the West keeps bailing them out of their difficulties.
The West should help provide medicine and healthcare for the unfortunate people affected by the disaster. But funds for the cleanup? By providing monetary aid, aren't we in the West discouraging these nations from being more responsible and more accountable for their actions?
The Office of International Health Studies responds:
Both the U.S. and other nations have worked hard to form close ties with the affected countries to provide scientific expertise and assistance in resolving problems that are of relevance to the entire world. In these endeavors our intent is to learn as much as we can from this terrible disaster, and use this information to help prevent any future disasters, and if they occur to resolve them effectively.
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Additional Comments:
Jack Warren-historian, University of Virginia
Charlottesville, Virginiarelative health risks
The potential for more nuclear accidents like that a Chernobyl obviously represents an enormous, long-lasting health risk for millions of people all over the world. Yet doesn't the environmental degradation associated with other industrial activities (e.g., electrical generation from fossil fuels), particularly in countries (like the former Soviet Union, where industrial production has been carried on with little regard to environmental impact) represent a more pervasive international health threat?
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