Excerpts from the 2008 UNSCEAR report on Chernobyl
It is instructive to compare the analyses of the Chernobyl accident provided by competent scientific organizations with those popularized by the media.
Here are the main excerpts from the chapter on Chernobyl in the 2008 report of UNSCEAR.
The “United Nations Scientific Committee on the Effects of Atomic Radiation” (UNSCEAR) is composed of high-level experts representing the concerned countries.
This committee regularly publishes reports on exposure to natural and artificial radiation, taking into account the evolution of scientific knowledge and professional experience.
The complete English version of the report can be accessed at the bottom of the page.
Sections No. 73, 74, and 75, not directly related to the consequences of the accident, can be found in the English version.
70. The accident that occurred in 1986 at the Chernobyl nuclear power plant in the former Soviet Union was the most serious accident in the history of civil nuclear power.
Two workers died immediately, and 134 plant employees and emergency personnel suffered from acute radiation syndrome (ARS), which proved fatal for 28 of them.
Several hundred thousand workers were later involved in site recovery operations.
71. The accident caused the largest uncontrolled release of radioactive material into the environment ever recorded in civil nuclear history; large amounts of radioactive substances were emitted into the atmosphere for about 10 days.
The radioactive cloud produced by the accident spread across the entire Northern Hemisphere, depositing significant amounts of radioactive materials over vast areas of the former Soviet Union and other parts of Europe, contaminating land, water, and the biosphere, and causing severe social and economic disruption for many segments of the population in what are now Belarus, the Russian Federation, and Ukraine.
Two radionuclides—short-lived iodine-131 (half-life 8 days) and long-lived cesium-137 (half-life 30 years)—were of particular importance because of the radiation doses they delivered to the population.
However, the doses were very different for these two radionuclides: iodine-131 delivered thyroid doses up to several grays during the weeks following the accident, while cesium-137 caused whole-body doses up to a few hundred millisieverts over the following years.
72. Contamination of fresh milk by iodine-131 and the lack of rapid countermeasures resulted in high thyroid doses, particularly among children in the former Soviet Union.
In the long term, mainly due to radioactive cesium, the population was also exposed to radiation—external exposure from deposited material and internal exposure from contaminated food.
However, long-term radiation doses were relatively low (the average additional dose during 1986–2005 in the “contaminated areas” of Belarus, the Russian Federation, and Ukraine was 9 mSv—roughly equivalent to a CT scan) and are not expected to cause significant health effects in the general population.
Despite this, the severe disruptions caused by the accident had a major social impact, generating great distress among affected populations.
No. 73, 74 and 75 …
76. Although a considerable amount of new data has become available, the main conclusions regarding the scale and nature of the health consequences of the Chernobyl accident remain essentially the same as in the Committee’s earlier reports of 1988 and 2000.
These conclusions are as follows:
(a) A total of 134 plant employees and emergency workers received high doses of radiation that resulted in acute radiation syndrome (ARS). Many also suffered from beta radiation-induced skin lesions.
(b) High radiation doses were fatal for 28 of these individuals within the first months following the accident.
(c) Although 19 survivors of acute radiation syndrome had died by 2006, their deaths were due to various causes not usually associated with radiation exposure.
(d) Radiation-related skin injuries and cataracts were among the main after-effects observed in ARS survivors.
(e) Apart from the emergency workers, several hundred thousand people were involved in recovery operations. Aside from some indications of increased leukemia and cataract incidence among those receiving the highest doses, there is to date no consistent evidence of radiation-related health effects in this group.
(f) A significant increase in thyroid cancer incidence among individuals exposed as children or adolescents in 1986 was observed in Belarus, Ukraine, and the four most affected regions of the Russian Federation. Between 1991 and 2005, over 6,000 cases were reported, most likely due to the consumption in 1986 of milk contaminated with iodine-131. Although thyroid cancer incidence in this group continues to rise, only 15 fatal cases were recorded up to 2005.
(g) Among the general population, there has so far been no consistent evidence of other health effects attributable to radiation exposure.
77. Although model-based predictions of possible increases in “solid” cancer incidence in the general population have been published, doses for all population groups concerned are relatively small and comparable to those from natural background radiation.
The Committee decided not to use models to predict the absolute number of health effects among populations exposed to low doses because of the unacceptable uncertainties in such projections.
Nevertheless, the Committee considers it appropriate to continue monitoring.
78. Based on 20 years of studies, it is possible to confirm the conclusions of the Committee’s 2000 report.
Essentially, individuals exposed as children to radioactive iodine released during the Chernobyl accident, and workers involved in emergency and recovery operations who received high radiation doses, face an increased risk of radiation-induced effects.
Most inhabitants of the region, however, were exposed to low-level radiation comparable to, or at most a few times higher than, annual natural background levels and do not need to live in fear of serious health consequences.