International response to the Chernobyl accident

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The accident at the Chernobyl nuclear power plant in the former U.S.S.R was the the second major single exposure to radiation of a substantial population, the first being the radiation from the atomic bombs in Hiroshima and Nagasaki, Japan, in 1945. The accident had significant and wide-ranging health impacts that continue to be monitored and assessed. The accident also produced a significant international response whose effectiveness is the subject of debate. The Chernobyl accident also generated significant debate about the safety of nuclear power plants.


An accident on the scale of Chernobyl would be a challenge to most countries. However, the Union of Soviet Socialist Republics (USSR) felt able to deal with the consequences, at least up until 1989, when it sought assistance from the WHO and the IAEA to evaluate the consequences of the accident in environmental and health terms. In response, the IAEA created the International Chernobyl Project, which oversaw a visit to the affected areas and made a comprehensive report on radiological consequences and protective measures. The team seems then to have been disbanded. Public concern was widespread, and the questions posed by the public to IAEA expert panels at public meetings show the extent of this concern. Following the breakup of the USSR, the consequences became the responsibility of three newly independent states: Ukraine, Russian Federation, and Belarus, the poorest and most heavily affected. Other UN organizations then became more involved. In May of 1991, the WHO headquarters (WHO/HQ) set up the International Project on the Health Effects of the Chernobyl Accident (IPHECA) with > $20 million in funding, primarily from Japan. By that time, the European Regional Office of the WHO (WHO/EURO) had a strong program in place, following its initial response to the accident, to assist its member states other than the USSR in their responses to the accident. In October 1991, WHO/EURO opened an office in Rome with an assignment including the effects of ionizing radiation on health; this office quickly became involved with the affected countries. Over the following year or two, the UN Office for the Coordination of Humanitarian Affairs (OCHA) undertook fundraising and provided humanitarian assistance for the three now very economically disadvantaged countries, as did the UN Educational, Scientific and Cultural Organization (UNESCO) (in recognition of the psychosocial consequences), the European Commission (EC), the Red Cross, the Sasakawa Foundation from Japan, the United States, Netherlands, Germany, and several other countries, non-governmental organizations, and charities. Many of these organizations, the EC, United States, and Japan, among others, also supported research.

Quite early on, attempts were made by the United States, WHO/HQ, and OCHA to coordinate both the humanitarian and research initiatives. One problem was a lack of clarity over the leadership of the newly independent states: the Russian Federation regarded itself as senior to the others, the accident occurred in Ukraine, and Belarus was the most affected country. The United States and WHO/HQ each claimed to have made exclusive agreements with the affected states—IPHECA to the effect that it was to be an umbrella under which all research and humanitarian activities would be coordinated, and the United States to the effect that it had priority where the conduct of research was concerned. OCHA claimed that its mandate overrode other humanitarian-linked agreements. The result was a serious lack of coordination and a fair measure of chaos on both humanitarian and research fronts.

The realization that there was a real radiation-related increase in the rare childhood thyroid cancer (CTC) dominated the research. By 1995, excess relative risks for some areas of Belarus were of the order of 200. This meant that almost every case of CTC was related to the accident and to radiation exposure. Studies were carried out to understand the molecular basis of the carcinogenesis and to look for a marker for radiation etiology that would aid the resolution of claims for compensation from nuclear industry workers and atomic test veterans. The U.S. research was carried out with the knowledge that Congress had ordered a reassessment of the thyroid doses from iodine-131 (131I) from the Nevada atomic weapons test series. In 1992, when the increase in CTC in Belarus was first reported, that reassessment was complete, although not yet made public. It showed that earlier assessments had significantly underestimated the doses. Before Chernobyl, this information would not have caused great concern in the United States because of the belief that, despite its radioactivity, 131I was not carcinogenic. It happened that the same National Cancer Institute (NCI) division was responsible for both the national dosimetric reassessment and the post-Chernobyl research. The former was not published until after a newspaper leak in 1997; the latter was a well-designed, long-term cohort study of a population of children with assigned thyroid doses, which was not expected to yield results for several decades. Many epidemiologic studies (mainly ecologic) built a strong circumstantial case for a link between exposure to 131I and thyroid cancer, definitively established by a case–control study in 2005. What the research has not so far yielded is a marker for radiation etiology. Chernobyl-related cancers have so far been predominantly papillary cancers and initially showed a high incidence of RET gene rearrangements, also found in spontaneous cancers. Papillary carcinoma has been increasing in incidence over the last half-century. Although partly due to ascertainment, a contribution of radiation from atomic weapons testing, medical, and dental sources cannot be excluded.

The accident at Chernobyl tested the capacities of the relevant international organizations, and their responses left much to be desired. Initially they were faced with the problem that, although many countries were exposed to radioactive fallout, it was regarded as an internal matter by the country in which it occurred. The next difficulty came with the breakup of that country, resulting in three separate countries containing heavily exposed populations. When outside assistance was eventually welcomed, there were many separate initiatives, and the level of coordination left a great deal to be desired.

The response of the WHO was hampered by internal disagreements. The $20 million used by WHO/HQ to fund the IPHECA program seems to have been largely spent on unproductive pilot projects and on providing training and laboratory and medical diagnostic equipment for the three countries. The largest had the least exposure. A separate initiative was taken by WHO/EURO, which set up the International Thyroid Project. The project suffered from inadequate funding but tried to achieve coordination of patient care and related research on consequences of iodine deficiency in the three affected countries. The WHO/HQ conference, held in November 1995 in Geneva, focused primarily on health issues. It was poorly prepared and attracted a significant number of dubious reports; the proceedings were not published in an accessible form. The lack of coordination between WHO/HQ and WHO/EURO, the political nature of some decisions of WHO/HQ, and the uncertainty over the division of its responsibility with the IAEA all contributed to its problems. In addition, other international organizations regarded the IPHECA program as such a failure that they were reluctant to collaborate with the WHO and would not accept its leadership as envisaged by the umbrella concept.

The IAEA was invited in 1989 to provide an assessment by international experts of the measures taken by the USSR. A team visited some of the affected areas in 1990, and a detailed report assessed the environmental contamination, radiation exposure, and health effects. Cases of thyroid cancer occurring in exposed children in both Belarus and Ukraine in 1990 were reported to the team but were apparently not followed up; the general tenor of the report suggests that they were largely discounted because of the belief that 131I had a low carcinogenic risk and that the latent period was too short. The report concluded that “there may be a statistically detectable increase in the incidence of thyroid carcinoma in the future.” The attitude of senior IAEA officials in the next few years was antagonistic toward reports of a radiation-related increase in thyroid carcinoma incidence. The mandate of the IAEA enjoins it to promote the peaceful use of nuclear technology, and this, together with its close links to the nuclear industry, would not make evidence of carcinogenic risks following a nuclear accident welcome news. The WHO seems to accept that the IAEA has the dominant role in the investigation of health effects of nuclear accidents, as clearly indicated in a recent report. This situation needs to be reassessed to avoid possible conflicts of interest.

The IAEA meeting in Vienna in 1996 provided a major opportunity for policy development for the coming years. The final statement by the conference president, Angela Merkel, then German Minister of the Environment, could have laid the foundations for a properly funded long-term study of all the potential health effects, but the statement, presumably prepared for her by IAEA officials, failed to provide any support or direction for this.

The EC was concerned about the consequences of Chernobyl, which took place in Europe and led to fallout across the European Union. It supported work on the incidence, scientific background and appropriate therapy of the thyroid cancers, and on the psychological consequences. The EC also provided extensive support for humanitarian aspects and to remedy the environmental consequences. It maintained close contact with the United States, but after one joint meeting with WHO/EURO in 1992, the EC very strongly discouraged any collaborative studies with the WHO for the next 5 years. Some collaboration was finally established after an independent group of scientists proposed creating a Chernobyl tumor bank to save unique material for future study. The EC provided core funding, and a collaborative project involving the three affected countries, the EC, United States (NCI), WHO/HQ, and Japan was created.

From 1991, UNESCO operated a very effective psychosocial rehabilitation program opening nine rehabilitation centers for adults and children, especially in areas where relocated people were housed. In particular these centers acted to promulgate reliable information about the risks entailed in living in contaminated areas.

In 2001, the United Nations Development Programme (UNDP) mounted a needs assessment mission, which identified exposed populations relocated or continuing to live in contaminated regions that “continue to face disproportionate suffering in terms of health, social conditions, and economic opportunity." The report described the most vulnerable groups as facing a “progressive downward spiral of living conditions induced by the consequences of the accident” and outlined a 10-year strategy for tackling and reversing this spiral. A key element of that strategy for recovery was to be a body called the International Chernobyl Research Board (ICRB), with a broad assignment including making recommendations for research. As noted above, the theoretical basis for understanding the effects of radiation on health have been in a state of flux since the early 1990s; the earlier concepts are still adhered to because they underpin the present radiation protection framework. Chernobyl has proved fertile ground for views that dissent from those of the establishment, with claims of much greater health impact based on observations or unsubstantiated risk coefficients; mistrust of many of the major international bodies has led to the perverse equation that dismissal by the establishment necessarily testifies to correctness. The ICRB was therefore envisaged as broader and more inclusive than established bodies such as the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR, the International Committee for Radiation Protection (ICRP), and the IAEA, and as a forum where all views could be debated in a rational way and mistrust lessened. Rather than creating an ICRB, the Chernobyl Forum, lacking the broader representation originally envisaged, was instigated on the initiative of the IAEA to evaluate the health and environmental consequences of the accident. The health section, led by the WHO/HQ, reported recently; this highly technical document builds on an earlier review. The report was launched as a landmark digest report, with a press release from WHO/HQ headed, “Chernobyl: The True Scale of the Accident”. It states, “A total of up to 4000 people could eventually die of radiation exposure from … Chernobyl.” The emphasis is on reassurance, but it is notable that the headline estimate of deaths is less than half the number that can be derived from the body of the report. Neither is it safe to assume that the very low death rate from thyroid cancer to date will apply to future cases, let alone assume that no further deaths from cancer will occur in the present cases. There is no previous experience of an accident such as this, and the long-term risks cannot be predicted with any certainty either in the heavily exposed areas or in the much wider areas with low-level exposures. Certainly there is a clear indication that there is a risk for low dose and low dose rate exposure, but there are also large uncertainties regarding its magnitude. The least that could have been expected from bodies such as the WHO and IAEA would have been support for long-term studies of such a unique event. Without these studies, society will not be able to assess the future risks associated with nuclear accidents, judge what precautions need to be taken, or plan the proper provision for health care.

What Can We Learn from the Chernobyl Experience?

Chernobyl was the first major accident to a civil nuclear power plant that released huge amounts of radioactive isotopes into the environment. It came as no surprise that there was worldwide public concern, even where doses to the public were tiny (although because of the large population involved, the collective dose was higher than in the immediately affected areas). There have been many smaller incidents involving accidental public exposure to radiation, most notably the Three Mile Island accident (Pennsylvania), arguably as severe as Chernobyl but with secondary containment (not present in the Chernobyl reactor), which largely prevented release of radioactivity to the environment. This public concern results to some degree from a lack of understanding of the effects of ionizing radiation, and it might be assumed that the international scientific community would be well equipped to allay at least some of these fears. Although this was attempted, initially with the International Chernobyl Project and later with three conferences around the 10th anniversary, it had not succeeded in 2001 when the UN needs assessment mission visited the affected regions 15 years after the accident.

As stated above, the lack of scientific consensus is at least in part due to the state of flux concerning the understanding of the ways in which radiation affects health, and it is understandable that bodies such as the ICRP are reluctant to change radiation protection standards. The IAEA is bound by a mandate to follow the ICRP dogma. The WHO should be freer to express alternative views. It is regrettable that the WHO played only a minor role in the International Chernobyl Project, which failed to recognize the importance of the CTCs reported to them.

The WHO and IAEA have both made major contributions, but their failures had a number of implications. The delay in the acceptance of the increase in CTC delayed assistance to the affected countries. The 1995/1996 conferences were to a degree mismanaged and missed a major opportunity to create a framework for the future. The major problems with IPHECA contributed greatly to the lack of international coordination and also meant that the International Thyroid Project was never adequately supported. Perhaps the biggest failure resulted from the widespread belief that the IAEA, and in its wake the WHO, wished to disbelieve or minimize the health consequences of Chernobyl, leaving the suspicion that health detriment was being covered up.

With globalization comes the increasing likelihood that accidents, including nuclear accidents, will occur, with impacts crossing national boundaries or presenting challenges beyond the capacity of individual states. Natural disasters such as hurricanes and earthquakes remind us of the high level of coordination and commitment required to respond effectively to such events. One can hardly celebrate the success of the international community in responding to the Chernobyl accident 20 years after the event.

Declining resources of gas and oil, the recognition of global climate change induced by burning of fossil fuels, and the threat of deliberate cessation of energy supply are forcing many countries to rethink the role of nuclear power in energy supply. As a salutary example of nuclear technology failure, the Chernobyl accident should give pause for thought. Clearly, rational decisions on future energy policy need to be made in light of the risks that alternative strategies incur. It is important to recognize that the accident happened in a reactor lacking secondary containment and that adequate precautions to protect public health were not always taken after the accident.

Action is needed to ensure adequate understanding of the health problems following Chernobyl; this requires creating and funding a structure to allow studies to continue for the lifetime of those exposed to the accident. The creation of the Atomic Bomb Commission (now renamed the Radiation Effects Research Foundation) was critical to understanding the health consequences of atomic bomb exposure. A similar organization could still provide an appropriate framework for Chernobyl studies. The rivalry and lack of coordination between many organizations, UN agencies, countries and others that followed Chernobyl must be avoided in future international-scale accidents. The UN should initiate an independent review of the response to Chernobyl, including the actions and assignments of the UN agencies involved. It should also advise on the organization necessary for future accidents. The Radiation Effects Research Foundation provides a model of international cooperation with independent scientists involved. Chernobyl is undoubtedly a more complicated situation, but the principles of cooperation rather than rivalry and independence remain essential.

We do not believe that the Chernobyl accident should necessarily be regarded as an insurmountable obstacle to future nuclear power development, although any new reactors must have secondary containment. We have stressed the uncertainties involved in predicting the long-term consequences of Chernobyl and believe this approach to be far preferable to either downplaying or exaggerating the risks. We do believe that the responses of the major international organizations to the Chernobyl accident were inadequate and show the need for a review by the United Nations of their assignments and coordination and for the development of a new strategy for dealing with future disasters. Above all, we believe that it would be a dereliction of duty by the world community if it did not ensure continuing study of the consequences of a tragic accident that we hope will never recur.

Editor's Note

This article is derived largely from Keith Baverstock and Dillwyn Williams, The Chernobyl Accident 20 Years On: An Assessment of the Health Consequences and the International Response, Environmental Health Perspectives, 114(9):1312:1317 (September 2006) doi:10.1289/ehp.9113. Topic editors and authors for the Encyclopedia of Earth have edited its content or added new information. That article is used here under the terms of its Creative Commons Attribution License. The use of information from the original article should not be construed as support for or endorsement by its author for any new information added by EoE personnel, or for any editing of the original content.

Further Reading



(2008). International response to the Chernobyl accident. Retrieved from


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