The Death Toll from Chernobyl - how can there be such disagreement?

The Death Toll from Chernobyl

How can there be such disagreement?

Jim Green, December 2011.

Nuclear advocates frequently claim that the death toll from the April 1986 Chernobyl nuclear reactor disaster was 30-60 deaths. They also claim, as the Uranium Information Centre (2004) does, that "there is no scientific evidence of any significant radiation-related health effects to most people exposed" to fallout from Chernobyl.

Such claims are ill-informed and/or misleading. It is widely acknowledged that it is difficult for epidemiological studies to demonstrate statistically-significant increases in cancers or other pathologies caused by Chernobyl fallout for various reasons such as the relatively high incidence of the diseases, the latency period of cancers, and limited data on disease incidence. However, difficulties in measuring impacts is no justification for trivialising or ignoring them.

The Uranium Information Centre (2004) states that a "greater, though not statistically discernible" incidence of leukaemia and other cancers is expected as a result of Chernobyl fallout. There is little expectation, however, of statistically-significant results. Further, when statistically-significant results are obtained, explanations other than Chernobyl can easily be suggested. For example, it is widely accepted that Chernobyl fallout has caused about 1800 cases of thyroid cancer but it has also been suggested that the rapid increase in thyroid cancers may be in part an artefact of the screening process (Uranium Information Centre, 2004). Likewise, a study attributing over 800 cancers in Sweden to Chernobyl fallout has been disputed (Anon., 2004). Another example is a debate over increased rates of infant leukaemia in several countries (Low Level Radiation Campaign, n.d.).

Some of the difficulties were described by Elizabeth Cardis (1996) from the International Agency for Research on Cancer: "Although some increases in the frequency of cancer in exposed populations have been reported, these results are difficult to interpret, mainly because of differences in the intensity and method of follow-up between exposed populations and the general population with which they are compared. ... The total lifetime numbers of excess cancers will be greatest among the 'liquidators' (emergency and recovery workers) and among the residents of 'contaminated' territories, of the order of 2000 to 4600 among each group (the size of the exposed populations is 200,000 liquidators and 6,800,000 residents of 'contaminated' areas). These increases would be difficult to detect epidemiologically against an expected background number of 41,500 and 800,000 cases of cancer respectively among the two groups."

Given the limitations of epidemiological studies, the only way to arrive at an estimate of the total numbers of cancers caused by the radioactive fallout from Chernobyl is to estimate the total collective dose and to apply standard risk estimates. Thus the IAEA (1996) estimate of a collective dose of 600,000 person-Sieverts over 50 years from Chernobyl fallout can be multiplied by a standard risk estimate of 0.04 fatal cancers per person-Sievert to give a total estimate of 24,000 fatal cancers. (The recent study by the US National Research Council (2005) lends weight to the Linear No Threshold model upon which the risk estimate is based.)

UN reports in 2005-06 estimated up to 4000 eventual deaths among the higher-exposed Chernobyl populations (emergency workers from 1986-1987, evacuees and residents of the most contaminated areas) and an additional 5,000 deaths among populations exposed to lower doses in Belarus, the Russian Federation and Ukraine (Chernobyl Forum, 2005; WHO, 2006.)

The estimated death toll rises further when populations beyond those three countries are included. For example, a study by Cardis et al (2006) reported in the International Journal of Cancer estimates 16,000 deaths. Dr Elisabeth Cardis (2006b), head of the IARC Radiation Group, said: "By 2065 (i.e. in the eighty years following the accident), predictions based on these models indicate that about 16,000 cases of thyroid cancer and 25,000 cases of other cancers may be expected due to radiation from the accident and that about 16,000 deaths from these cancers may occur."

Other studies estimate a still higher death toll. UK radiation scientists Dr Ian Fairlie and Dr David Sumner (2006) estimate 30,000 to 60,000 deaths. A 2006 report commissioned by Greenpeace estimates a death toll of about 93,000. According to Greenpeace (2006): "Our report involved 52 respected scientists and includes information never before published in English. It challenges the UN International Atomic Energy Agency Chernobyl Forum report, which predicted 4,000 additional deaths attributable to the accident as a gross simplification of the real breadth of human suffering. The new data, based on Belarus national cancer statistics, predicts approximately 270,000 cancers and 93,000 fatal cancer cases caused by Chernobyl. The report also concludes that on the basis of demographic data, during the last 15 years, 60,000 people have additionally died in Russia because of the Chernobyl accident, and estimates of the total death toll for the Ukraine and Belarus could reach another 140,000."

While the Chernobyl death toll is subject to uncertainty, the broader social impacts are all too clear, including those resulting from the permanent relocation of about 220,000 people from Belarus, the Russian Federation, and the Ukraine. As the OECD's Nuclear Energy Agency notes, Chernobyl "had serious radiological, health and socio-economic consequences for the populations of Belarus, Ukraine and Russia, which still suffer from these consequences."


Anon., November 20, 2004, "Study Suggests Chernobyl Affected Sweden", Associated Press,

Cardis, Elizabeth, April 1996, "Estimated Long Term Health Effects of the Chernobyl Accident", Proceedings of international conference, One Decade After Chernobyl – Summing up the consequences of the accident, Vienna, April 1996, sponsored by EU, IAEA & WHO.

Cardis E, Krewski D, Boniol et al, Estimates of the Cancer Burden in Europe from Radioactive Fallout from the Chernobyl, International Journal of Cancer, Volume 119, Issue 6, pp.1224-1235, Published Online: 20 Apr 2006,

Cardis, Elizabeth, 2006b, media release,

Chernobyl Forum, 2005, Chernobyl’s Legacy, second revised version,

Fairlie and Sumner, 2006, The Other Report on Chernobyl, commissioned by European Greens, <

Greenpeace, 2006, Chernobyl death toll grossly underestimated,

International Atomic Energy Agency, 1996, "Long-term Committed Doses from Man-made Sources," IAEA Bulletin, Vol.38, No.1. Click here to download PDF

Low Level Radiation Campaign, n.d., "Shooting the Miners' Canary", <>.

National Research Council (of the US National Academy of Sciences), 2005, "Health Risks from Exposure to Low Levels of Ionizing Radiation (BEIR VII – Phase 2)", written by the NRC's Board on Radiation Research Effects,

Organisation for Economic Cooperation and Development, 1998, "Uranium 1997: Resources, Production and Demand", Paris: OECD.

Uranium Information Centre, 2004, "Chernobyl Accident", Nuclear Issues Briefing Paper 22,

World Health Organization, 2006,


How many more lives will Chernobyl claim?

Rob Edwards

New Scientist magazine

06 April 2006, page 11, Issue 2546


THE cloud of radiation spewed out by the world's worst nuclear accident at Chernobyl 20 years ago could kill up to 60,000 people - 15 times as many as officially estimated. So say scientists who are accusing two UN organisations, the International Atomic Energy Agency (IAEA) and the World Health Organization (WHO), of downplaying the impact of the accident.

Chernobyl reactor number 4 in Ukraine was ripped apart by an explosion on 26 April 1986, and burned for 10 days. It disgorged a massive amount of radioactivity - up to 14 exabecquerels (14 × 1018 becquerels) - over Europe and the rest of the world.

Last September, the IAEA and the WHO released a report which claimed to reveal "the true scale of the accident". Its headline conclusion that radiation from the accident would kill a total of 4000 people was widely reported (New Scientist, 10 September 2005, p 14), but that figure is now being challenged. In a report this week for the Green group in the European Parliament, Ian Fairlie and David Sumner, two independent radiation scientists from the UK, say that the death toll from cancers caused by Chernobyl will in fact lie somewhere between 30,000 and 60,000.

They accuse the IAEA/WHO report of ignoring its own prediction of an extra 5000 cancer deaths in the less contaminated parts of Ukraine, Belarus and Russia, and of failing to take account of many thousands more deaths in other countries, where more than half of Chernobyl's fallout ended up. "It is poor scientific practice to issue figures which only reflect part of the real situation," Fairlie says.

Zhanat Carr, a radiation scientist with the WHO in Geneva, says the 5000 deaths were omitted because the report was a "political communication tool". "Scientifically, it may not be the best approach," she admitted to New Scientist. She also accepts that the WHO estimates did not include predicted cancers outside Ukraine, Belarus and Russia. The health impact in other countries will be "negligible", she says, adding that there is no epidemiological research showing otherwise. The WHO "has no reasons to deliberately mislead anyone", she insists. "WHO's position is independent, free from political issues, and based on scientific evidence of the highest quality." The IAEA refused to comment.

Fairlie and Sumner's accusations are backed by other experts. The IAEA/WHO report "misrepresents reality by significantly underestimating the number of cancer deaths", says Timothy Mousseau of the University of South Carolina in Columbia. A paper co-authored by Mousseau and published this week in Trends in Ecology and Evolution (DOI: 10.1016/j.tree.2006.01.008) points to studies suggesting that fallout from Chernobyl has already caused germline mutations in animals and plants.

Elizabeth Cardis, a radiation specialist from the WHO's International Agency for Research on Cancer in Lyon, France, says that 30,000 to 60,000 cancer deaths is "the right order of magnitude". She is due to publish a study later this month that will estimate the number of excess cancers attributable to Chernobyl amongst 570 million Europeans. Though they will be difficult to detect, as they will only form a tiny proportion of the millions of cancer deaths from all causes, this doesn't mean that they should be ignored, Cardis says. "They are real people who suffer from the accident."