Consequences for health6 April 2006
The IAEA and WHO have produced a definitive account of the health effects of the Chernobyl accident 20 years after it occurred. It finds some effects directly linked to the radioactivity release, and many more the result of fear and uncertainty.
The International Atomic Energy Agency (IAEA) convened an expert working group of scientists to summarise the environmental effects of the Chernobyl accident, and the World Health Organization (WHO) convened an expert group to summarise the health effects and medical care programmes in the three most affected countries. The work was carried out for the Chernobyl Forum, an initiative of the IAEA, in cooperation with WHO, United Nations Development Programme (UNDP), Food and Agriculture Organization (FAO), United Nations Environment Programme (UNEP), United Nations Office for the Coordination of Humanitarian Affairs (UN-OCHA), United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), and the World Bank, as well as the governments of Belarus, Russia and Ukraine.
Three population categories were exposed:
- Emergency and recovery operation workers who worked at the plant after the accident.
- Inhabitants evacuated from contaminated areas.
- Inhabitants of contaminated areas who were not evacuated.
Some of the reactor staff and emergency workers received, on 26 April 1986, high doses of external gamma radiation (estimated at 2-20Gy), and as a result 28 of them died within the first four months from radiation and thermal burns, and another 19 died over the years up to 2004. In addition, two members of reactor staff died as a result of the explosion (one immediately, the other within a few hours).
The doses received by recovery workers who were employed for short periods during the four years following the accident ranged up to about 500mSv, with an average of about 100mSv, according to the state registries of Belarus, Russia and Ukraine.
Exposure levels of the evacuees from the Chernobyl accident area were also of concern. Doses, estimated some time after they occurred by careful evaluation of all available information, were 17mSv on average to Ukrainian evacuees, with doses to individuals ranging from 0.1 to 380mSv. The average dose to Belarusian evacuees was 31mSv, with the highest average dose in two villages being about 300mSv.
Ingestion of food contaminated with radioactive iodine resulted in significant doses to the thyroids of inhabitants of the contaminated areas varying according to age, level of ground contamination with I-131, and milk consumption rate. Drinking milk from cows that ate contaminated grass immediately after the accident was one of the main reasons why so many children subsequently developed thyroid cancer. Reported individual thyroid doses ranged up to about 50Gy, with average doses in contaminated areas being 0.03-0.3Gy. The doses to Pripyat residents were substantially reduced by timely distribution of stable iodine tablets.
The general public has been exposed during the past 20 years to external sources (Cs-137 on soil) and by the intake of radionuclides (mainly Cs-137) with food, water and air. The average effective doses for the general population of contaminated areas accumulated in 1986-2005 were estimated to be 10-20mSv in various regions. Some residents received a few hundred mSv, and others received lower doses.
The vast majority of the five million people in contaminated areas of Belarus, Russia and Ukraine currently receive an annual effective dose of less than 1mSv. About 100,000 residents of the more contaminated areas still receive more than 1mSv annually. Future reduction of exposure levels is expected to be slow (3-5% per year), but the great majority of dose from the accident has already been accumulated.
NUMBER OF DEATHS
Claims have been made that tens or even hundreds of thousands of persons have died as a result of the accident. These are exaggerated: the total number of people that could have died or could die in the future due to Chernobyl-originated exposure over the lifetime of emergency workers and residents of most contaminated areas is estimated to be around 4000. This includes 47 emergency workers who died of acute radiation syndrome (ARS) in 1986 and other causes in later years; nine children who died of thyroid cancer; and an estimated 3940 people that could die from cancer contracted as a result of radiation exposure (from the 200,000 emergency and recovery operation workers from 1986-1987, 116,000 evacuees, and 270,000 residents of most contaminated areas).
The number of deaths due to ARS during the first year following the accident is well documented. According to UNSCEAR (2000), ARS was originally diagnosed in 237 reactor and emergency workers but later confirmed with detailed clinical analysis in 134 persons. In many cases the ARS was complicated by extensive beta radiation skin burns and sepsis. Among these workers, 28 persons died in 1986 due to ARS, and 19 more died in 1987-2004 of various causes. Among the general population affected by the Chernobyl radioactive fallout, however, the radiation doses were quite low, and ARS and associated fatalities did not occur.
By contrast, the number of deaths over the past 20 years that may have been attributable to the accident are estimates. In all the groups studied, both emergency workers and resident populations, mortality increase, compared to control groups, was statistically insignificant or very low. Estimates related to projected deaths in the future are even less certain, as they are subject to other major confounding factors, so the actual number of deaths caused by the accident is unlikely ever to be known with precision.
Direct radiation-epidemiological studies performed since 1986 have so far revealed no radiation-induced increase in the mortality of the general population (other than thyroid cancer in children) or non-cancer diseases above the spontaneous level.
Some radiation-induced increase in morbidity and mortality caused specifically by leukaemia, solid cancers and circulatory system diseases has been reported in Russian emergency and recovery operation workers. According to data from the Russian registry, about 5% of fatalities that occurred in 1991-1998 in the cohort under study of 61,000 Russian workers exposed to an average dose of 107mSv could be caused by radiation-induced diseases. The absolute number of deaths in this cohort attributable to radiation caused by solid cancers, circulatory system diseases and leukaemia was estimated to be about 230 cases.
Thyroid cancer in children
The thyroid gland is one of the organs most susceptible to cancer induction by radiation from I-131. A substantial increase in thyroid cancer among those exposed as children was recorded subsequent to the accident. In 1992-2000 in Belarus, Russia and Ukraine about 4000 cases of thyroid cancer were diagnosed among those who were children and adolescents (0-18 years) at the time of the accident.
For the 1152 thyroid cancer cases diagnosed among children in Belarus during 1986–2002 and treated, the survival rate was 98.8%. Eight patients died due to progression of the thyroid cancer, and six children died from other causes. One patient with thyroid cancer died in Russia. We can be reasonably certain that most of the thyroid cancer incidence can be attributed to radiation.
Leukaemia, solid cancers and circulatory diseases
Recently, a slight increase in the remote incidence of cardiovascular diseases attributable to radiation at higher doses has been observed in some study groups. Because of differing doses received, an increased risk of leukaemia associated with radiation exposure from Chernobyl may become evident for emergency and recovery operation workers, but would be quite unlikely for the general population.
The most recent studies suggest a twofold increase in the incidence of non-CLL leukaemia (non chronic lymphocytic leukaemia) between 1986 and 1996 in Russian emergency and recovery operation workers exposed to more than 150mGy (external dose). Since the risk of radiation induced leukaemia decreases several decades after exposure, its contribution to morbidity and mortality is likely to become less significant as time progresses.
There is no convincing evidence that the incidence of leukaemia has increased in children or adult residents of the exposed populations in Russia and Ukraine.
There appears to be some recent increase in Russian emergency and recovery operation workers’ morbidity and mortality caused by solid cancers and possibly circulatory system diseases.
It is well known from long-term epidemiological studies (such as the atomic bomb survivors) that elevated radiation-induced solid cancer morbidity is sustained for decades after exposure, following a latency period of about ten years. Medical care and annual examinations of highly exposed Chernobyl workers should continue.
Examinations of eyes of children and emergency and recovery operation workers clearly show that cataracts may develop in association with exposure to radiation from the Chernobyl accident. The data from studies of emergency and recovery workers suggests that exposures to doses down to about 250mGy may be cataractogenic.
Inherited or reproductive effects
Because of the relatively low dose levels to which the population of the Chernobyl-affected regions was exposed, there is no evidence nor any likelihood of observing decreased fertility in the general population. These doses are also unlikely to have any effect on the number of stillbirths, adverse pregnancy outcomes, delivery complications or the overall health of children. Birth rates may be lower in contaminated areas because of concern about having children, and this issue is obscured by the very high rate of medical abortions. No discernable increase in hereditary effects caused by radiation is expected based on the low risk coefficients estimated by UNSCEAR (2001) or in previous reports on Chernobyl health effects. Since 2000, there has been no new evidence provided to change this conclusion.
The modest but steady increase in reported congenital malformations in both contaminated and uncontaminated areas of Belarus since 1986 does not appear to be radiation related.
Stress symptoms have been reported in exposed populations. Three studies found that exposed populations had anxiety levels twice as high as controls, and they were more likely to report multiple unexplained physical symptoms and subjective poor health. The context in which the Chernobyl accident occurred makes the findings difficult to interpret because of the complicated series of events unleashed by the accident, the multiple extreme stresses and culture-specific ways of expressing distress. In addition, individuals in the affected population were officially given the label ‘Chernobyl victims’.
Pripyat about five years after the accident. The ferris wheel in the background was part of a fair built in anticipation of May Day celebrations that never took place
The huge costs to the Soviet Union and then to Belarus, the Russian Federation and Ukraine, are impossible to calculate precisely. However, the magnitude of the impact is clear from a variety of government estimates from the 1990s, which put the cost of the accident, over two decades, at hundreds of billions of dollars.
The scale of the burden is clear from the wide range of costs incurred, both direct and indirect, including:
- Direct damage caused by the accident.
- Actions to seal off the reactor and mitigate the consequences in the exclusion zone.
- Resettlement of people and construction of new housing and infrastructure to accommodate them.
- Social protection and health care provided to the affected population.
- Research on environment, health and production of clean food.
- Radiation monitoring of the environment.
- Radioecological improvement of settlements and disposal of radioactive waste.
In Ukraine, 5-7% of government spending each year is still devoted to Chernobyl-related benefits and programmes. In Belarus, government spending on Chernobyl amounted to 22.3% of the national budget in 1991, declining gradually to 6.1% in 2002.
The lion’s share goes to social benefits for some 7 million ‘Chernobyl victims’. Governments face a difficult choice of either reneging on payments or restructuring benefits to target those groups most at risk to radiation hazards and to assist those confronted with poverty.
The agricultural sector was the area of the economy worst hit by the effects of the accident (see next article). However, it is crucial to note that the region also faced great economic turmoil in the 1990s owing to factors completely unrelated to radiation. The disruption of trade accompanying the collapse of the Soviet Union, the introduction of market mechanisms, prolonged recessionary trends, and Russia’s rouble crisis of 1998 all combined to undercut living standards, heighten unemployment and deepen poverty. The result is that the contaminated regions face a higher risk of poverty than elsewhere.
Since the Chernobyl accident, some 350,000 people have been relocated away from the most severely contaminated areas, 116,000 of them immediately after the accident. Although resettlement reduced the dose, it was for many a deeply traumatic experience. Paradoxically, people who remained in their villages (and those who were evacuated and then returned to their homes despite restrictions) have coped better.
Communities in the contaminated areas suffer from a highly distorted demographic structure. They have negative attitudes in self-assessments of health and a strong sense of lack of control over their own lives. The affected populations exhibit a widespread belief that exposed people are in some way condemned to a shorter life expectancy. Such fatalism is also linked to a loss of initiative and to dependency on assistance from the state. Anxiety over the effects of radiation on health shows no sign of diminishing. Indeed, it may even be spreading beyond the affected areas into a wide section of the population.
In this context, it is crucial to note that adult mortality has been rising alarmingly across the former Soviet Union for several decades. Life expectancy has declined precipitously, particularly for men, and in the Russian Federation stood at an average of 65 in 2003. The main causes of death in the Chernobyl-affected region are the same as those nationwide rather than any radiation-related illnesses.
The extensive system of Chernobyl-related benefits has created a dependency culture that is a major barrier to the region’s recovery. Rehabilitation began on a hugely ambitious scale, including construction of housing, schools, and hospitals, and roads, water and electricity supply and sewerage. Because of the risk that was believed to be involved in burning locally produced wood and peat, many villages were provided with access to gas supplies for heating and cooking. This involved laying down a total of 8980km of gas pipeline. Such a massive investment programme proved unsustainable. Funding for Chernobyl programmes has declined steadily over time, leaving many projects half completed.
Some 7 million people are now receiving (or at least entitled to) special allowances, pensions and healthcare privileges as a result of being categorised as in some way affected by Chernobyl. The benefits confer certain advantages and privileges even to those citizens who had been exposed to low levels of radiation or who continue to live in only mildly contaminated locations, where the level of radiation is similar to natural background levels in some other European countries.
By the late 1990s, Belarusian and Russian legislation provided more than 70, and Ukrainian legislation more than 50, different privileges and benefits for Chernobyl victims. The system also guaranteed allowances, some of which were paid in cash, while others took the form of, for example, free meals for schoolchildren and free holidays (up to half a million per year in Ukraine and Belarus).
The number of people claiming Chernobyl-related benefits soared over time, rather than declined. As the economic crisis of the 1990s deepened, registration as a victim of Chernobyl became for many the only means of access to an income and to vital aspects of health provision, including medicines. Corruption played a role. Targeting resources to those whose health has actually suffered from the catastrophe should be a high priority.
Current scientific knowledge suggests that a small but important minority, numbering between 100,000-200,000, is caught in a downward spiral of isolation, poor health and poverty, and needs substantial material assistance to rebuild their lives. This group includes those who continue to live in severely contaminated areas and who are unable to support themselves adequately, unemployed resettlers and those whose health is most directly threatened. Resources should be focused on resolving their needs.
A second group, numbering several hundreds of thousands of individuals, consists of those whose lives have been directly and significantly affected by the consequences of the accident but who are already in a position to support themselves. This group includes resettlers who have found employment and many of the former cleanup workers. The priority here should be to help these people to normalise their lives as quickly and as far as is possible.
A third group consists of a much larger number of people, totalling several million in the three countries, whose lives have been influenced by the accident primarily in that they have been labelled as, or perceive themselves as, actual or potential victims of Chernobyl. Here the main need is for full, truthful and accurate information on the effects of the accident based on dependable and internationally recognised research, coupled with access to good quality mainstream provision in healthcare and social services, and to employment.
The Chernobyl Forum report, Chernobyl’s Legacy: Health, Environmental and Socio-Economic Impacts, is available from the IAEA, Wagramer Strasse 5, P.O. Box 100, A-1400 Vienna, AustriaRelated ArticlesConsequences for agriculture
|Spread of radionuclides|
The cloud from the burning reactor at Chernobyl spread radioactive materials, especially iodine and caesium radionuclides, over much of Europe. Iodine-131 was most significant in contributing to thyroid doses, but has a short half life (eight days) and largely
|A plan of action|
At the Chernobyl Forum meeting in April 2005, forum participants from Belarus, the Russian Federation and Ukraine requested the forum to develop recommendations for the governments of these three countries on special healthcare programmes and environmental remediation. The document was prepared by the forum secretariat, based on the recommendations presented in the forum’s technical reports.
Medical care and annual examinations of the workers who recovered from acute radiation syndrome (ARS) and other highly exposed emergency workers should continue. This should include periodic examination for cardiovascular disease. Current follow-up programmes for those persons with whole body exposures of less than 1Gy should be reconsidered as they are unlikely to be cost effective or beneficial to patients.
• Populations known to be particularly sensitive subgroups that are at much higher risk than the general population should be considered for screening.
Long-term monitoring of radionuclides (especially, Cs-137 and Sr-90) in various environmental compartments is required:
• To assess current and predict future levels of human exposure and contamination.
As current human exposure levels caused by the Chernobyl fallout are generally well known and they change slowly, large-scale monitoring of foodstuffs, whole-body counting of individuals, and provision of dosimeters to members of the general population are no longer necessary.
ECONOMIC AND SOCIAL POLICY
Current scientific knowledge about the impact of the disaster suggests that five general principles should underlie any approach to tackling the consequences of the accident:
• A holistic view of the needs of the individuals and communities concerned and, increasingly, of the needs of society as a whole.
Studies have confirmed that efforts to disseminate information to the population have fallen short of their aims. Accurate information on living in conditions of low-dose radiation is available, yet it is either not reaching some people, or people are unable to digest it or act upon it. Any new information strategy should embrace a comprehensive approach to promoting healthy lifestyles, and not simply focus on radiation hazards.
• Streamline and refocus government programmes to provide support to those who have been directly affected by the accident.