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The Wikipedia article on this is littered with [citation needed] and a commenter on hacker news linked to it while stating:

Chernobyl cost several hundred thousand lives. Let's hope and pray Fukushima will not exact a similar cost.

However I read a recent article in the Guardian about a journalist that was seemingly desperately trying to figure out what research backs up such claims. In the link-bait titled article The unpalatable truth is that the anti-nuclear lobby has misled us all he states:

For the last 25 years anti-nuclear campaigners have been racking up the figures for deaths and diseases caused by the Chernobyl disaster, and parading deformed babies like a medieval circus. They now claim 985,000 people have been killed by Chernobyl, and that it will continue to slaughter people for generations to come. These claims are false.

The UN Scientific Committee on the Effects of Atomic Radiation (Unscear) is the equivalent of the Intergovernmental Panel on Climate Change. Like the IPCC, it calls on the world's leading scientists to assess thousands of papers and produce an overview. Here is what it says about the impacts of Chernobyl.

Of the workers who tried to contain the emergency at Chernobyl, 134 suffered acute radiation syndrome; 28 died soon afterwards. Nineteen others died later, but generally not from diseases associated with radiation. The remaining 87 have suffered other complications, including four cases of solid cancer and two of leukaemia.

In the rest of the population there have been 6,848 cases of thyroid cancer among young children – arising "almost entirely" from the Soviet Union's failure to prevent people from drinking milk contaminated with iodine 131. Otherwise "there has been no persuasive evidence of any other health effect in the general population that can be attributed to radiation exposure". People living in the countries affected today "need not live in fear of serious health consequences from the Chernobyl accident".

Is the probably widespread belief that Chernobyl disaster has caused hundreds of thousand, or even tens of thousand deaths true when examining the literature?

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@djerry - Okay even if that's true then we need to quantify it. 1 person per year is "taking lives years after the event", but hardly cause for alarm. –  Kit Sunde Apr 12 '11 at 9:40
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@djerry - Of course you can quantify it. It's surely more than 1 and less than 10 billion. We also know what death rate you can expect from not having had a nuclear meltdown, so we can discount those as being caused by Chernobyl. You can probably not quantify it, but researchers can probably narrow it down pretty well. It's not unknowable. –  Kit Sunde Apr 12 '11 at 10:58
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I'm not asking about every possible event that could happen, and wars can hardly be attributed to Chernobyl so that's a straw man. I'm asking about a very specific incident where we have a ton of research. I was also asking this question in the past-tense and wasn't wondering about future deaths (though I don't see why that would be impossible to predict). I also don't see why infertility has anything to do with death, unless you are claiming an unborn person is dead. That said it's perfectly possible to make predictions for the death count for 100 years, it's just a matter of probabilities. –  Kit Sunde Apr 12 '11 at 11:28
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Interestingly, low to moderate doses of radiation often increase life expectancy, see e.g. opinion.financialpost.com/2011/03/21/… ; It's noteworthy that Mary Currie, who coined the word radiation, who strapped uranium to her arms, and who kept radioactive isotopes around her home to the point where her cookbook is still today condemned to a lead container for its radioactivity, nevertheless lived to the age of 66 - 5 years past the life expectancy of 61 at the time of her death. –  Brian M. Hunt Apr 12 '11 at 13:58
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@Brian Marie Curie died due to the radiation she was exposed to in her experiments. She's not a good example if you want to argue that radioactivity has positive effects. –  Fabian Apr 12 '11 at 18:15

4 Answers 4

up vote 48 down vote accepted

From the World Health Organisation (2005)

The total number of deaths already attributable to Chernobyl or expected in the future over the lifetime of emergency workers and local residents in the most contaminated areas is estimated to be about 4000. This includes some 50 emergency workers who died of acute radiation syndrome and nine children who died of thyroid cancer, and an estimated total of 3940 deaths from radiation-induced cancer and leukemia among the 200 000 emergency workers from 1986-1987, 116 000 evacuees and 270 000 residents of the most contaminated areas (total about 600 000). These three major cohorts were subjected to higher doses of radiation amongst all the people exposed to Chernobyl radiation.

The estimated 4000 casualties may occur during the lifetime of about 600 000 people under consideration. As about quarter of them will eventually die from spontaneous cancer not caused by Chernobyl radiation, the radiation-induced increase of about 3% will be difficult to observe. However, in the most highly exposed cohorts of emergency and recovery operation workers, some increase in particular cancers (e.g., leukemia) has already been observed.

Confusion about the impact has arisen owing to the fact that thousands of people in the affected areas have died of natural causes. Also, widespread expectations of ill health and a tendency to attribute all health problems to radiation exposure have led local residents to assume that Chernobyl related fatalities were much higher than they actually were.


'Several hundred thousand' may not have died, but

More than 350 000 people have been relocated away from the most severely contaminated areas, 116 000 of them immediately after the accident. Even when people were compensated for losses, given free houses and a choice of resettlement location, the experience was traumatic and left many with no employment and a belief that they have no place in society.

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“Even when people were compensated for losses” – it should be noted that most weren’t. –  Konrad Rudolph Apr 12 '11 at 12:03
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"... experience was traumatic and left many with no employment and a belief that they have no place in society" -- I feel that this argument is really dragged in. This was the last years of Soviet. And a lot of people felt that way. Especially those who had any personal problems so they could clearly see that the system doesn't care about them. –  Kostya Apr 12 '11 at 15:22
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How reliable is the WHO figure, though? Under WHO's agreement with IAEA, while IAEA has no formal say in what WHO does, there is mandatory cooperation. So how do we have confidence that their reports are unbiased? Are there completely independent studies? –  Gilles Apr 12 '11 at 17:49
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I would consider WHO reports rather objective, and have never heard evidence or credible suggestions that IAEA or other organizations would have tried to exert their influence. But since it is impossible to prove non-existence of something, what would make sense is to point to some actual credible suggestions there has been coercion; or, assume there is none. –  StaxMan Apr 12 '11 at 18:46
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Even if we'd assume that there was a IAEA-induced bias, in which direction would it be? The IAEA isn't exactly a fan of the RBMK design. –  MSalters Apr 14 '11 at 8:18

Taken from here:

http://www.who.int/mediacentre/news/releases/2005/pr38/en/index.html

As of mid-2005, however, fewer than 50 deaths had been directly attributed to radiation from the disaster, almost all being highly exposed rescue workers, many who died within months of the accident but others who died as late as 2004.

About 4000 cases of thyroid cancer, mainly in children and adolescents at the time of the accident, have resulted from the accident’s contamination and at least nine children died of thyroid cancer; however the survival rate among such cancer victims, judging from experience in Belarus, has been almost 99%.

Most emergency workers and people living in contaminated areas received relatively low whole body radiation doses, comparable to natural background levels. As a consequence, no evidence or likelihood of decreased fertility among the affected population has been found, nor has there been any evidence of increases in congenital malformations that can be attributed to radiation exposure.

“This was a very serious accident with major health consequences, especially for thousands of workers exposed in the early days who received very high radiation doses, and for the thousands more stricken with thyroid cancer. By and large, however, we have not found profound negative health impacts to the rest of the population in surrounding areas, nor have we found widespread contamination that would continue to pose a substantial threat to human health, within a few exceptional, restricted areas.”

Generally speaking it would seem that the consequences of a nuclear disaster are drastically overestimated and the science in no way backs up the hysteria in the media whenever anything nuclear is mentioned.

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The key here is “directly attributed”. This is a completely useless measure: the radioactive fallout caused by the Chernobyl disaster was extremely widespread and it’s very well established that elevated radiation levels correlate with elevated cancer incidence. It’s a pity that these cases cannot be traced directly but this doesn’t mean we can simply pretend that there is no connection. I’m not talking about local incidence here. We don’t know any overall number of the elevated cancer rate due to the disaster but that number is certainly not 0. –  Konrad Rudolph Apr 13 '11 at 14:46
    
I disagree, if we cannot directly attribute a death to radiation then it is quite valid to discount it. I could make up all sorts of scenarios that could have caused a death but without evidence to directly attribute a death to a specific cause it is all conjecture and meaningless. –  Ardesco Apr 13 '11 at 15:52
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@Ardesco “then it is quite valid to discount it” – only if we don’t know from other sources that this will result in (completely) wrong information. And we do know that, from the fallout data from Hiroshima and Nagasaki. The connection between radioactive fallout and elevated cancer rates is uncontested, as are the (partially hugely) elevated radiation levels all over Europe after Chernobyl. The WHO summary is relying on the assumption that either of these statements is false. This is a huge claim and would need careful demonstration. –  Konrad Rudolph Apr 13 '11 at 19:48
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@Monkey Was that in reply to my comment? Because that’s not what I meant. I’m not talking about “directly attributed”, I’m claiming that we have strong evidence to suspect that Chernobyl has caused a lot of deaths, even though we cannot directly attribute them. –  Konrad Rudolph Apr 13 '11 at 19:49
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@MSalters “there is no medical evidence for or against a maximal safe dose” – I’m not talking about dose thresholds. I’m talking about the accepted dose-response relationship between radiation (dose equivalence) and cancer. And I unfortunately don’t have time to dig up sources (hence this is a comment rather than an answer) but most of this can be found in any text book on radiology. Furthermore, many DNA repair mechanisms are “heuristics” and can fail all the time, even with only low radiation exposure. Even a single CAT scan has the potential of causing cancer, albeit with low incidence. –  Konrad Rudolph Apr 14 '11 at 8:41

Okay, now let's try another take with more numbers. I found a nice page with many references (NB: I haven't personally checked them all, but I've seen the Chernobyl Forum report and it lines up). Relevant quotes of the specific death numbers:

Apart from the initial 31 deaths (two from the explosions, one reportedly from coronary thrombosis (heart attack), and 28 firemen and plant personnel from acute radiation syndrome), the number of deaths resulting from the accident is unclear and a subject of considerable controversy. According to the 2006 report of the UN Chernobyl Forum's 'Health' Expert Group: "The actual number of deaths caused by this accident is unlikely ever to be precisely known."
On the number of deaths due to acute radiation syndrome (ARS), the Expert Group report states: "Among the 134 emergency workers involved in the immediate mitigation of the Chernobyl accident, severely exposed workers and fireman during the first days, 28 persons died in 1986 due to ARS, and 19 more persons died in 1987-2004 from different causes. Among the general population affected by the Chernobyl radioactive fallout, the much lower exposures meant that ARS cases did not occur.
[...]
Regarding the emergency workers with doses lower than those causing ARS symptoms, the Expert Group report referred to studies carried out on 61,000 emergency Russian workers where a total of 4995 deaths from this group were recorded during 1991-1998. "The number of deaths in Russian emergency workers attributable to radiation caused by solid neoplasms and circulatory system diseases can be estimated to be about 116 and 100 cases respectively." Furthermore, "the number of leukaemia cases attributable to radiation in this cohort can be estimated to be about 30." Thus, 4.6% of the number of deaths in this group are attributable to radiation-induced diseases. (The estimated average external dose for this group was 107 mSv.)
[...]
The picture is even more unclear for the populations of the areas affected by the Chernobyl fallout. However, the report does link the accident to an increase in thyroid cancer in children: "During 1992-2000, in Belarus, Russia and Ukraine, about 4000 cases of thyroid cancer were diagnosed in children and adolescents (0–18 years), of which about 3000 occurred in the age group of 0–14 years. For 1152 thyroid cancer patient cases diagnosed among Chernobyl children in Belarus during 1986-2002, the survival rate is 98.8%. Eight patients died due to progression of their thyroid cancer and six children died from other causes. One patient with thyroid cancer died in Russia."
[...]
"The predicted lifetime excess cancer and leukaemia deaths for 200,000 liquidators, 135,000 evacuees from the 30 km zone, 270,000 residents of the SCZs ['strict control zones'] were 2200 for liquidators, 160 for evacuees, and 1600 among residents of the SCZs. This total, about 4000 deaths projected over the lifetimes of the some 600,000 persons most affected by the accident, is a small proportion of the total cancer deaths from all causes that can be expected to occur in this population. It must be stressed that this estimate is bounded by large uncertainties."
Beyond this, "for the further population of more than 6,000,000 persons in other contaminated areas, the projected number of deaths was about 5000. This latter estimate is particularly uncertain, as it is based on an average dose of just 7 mSv, which differs very little from natural background radiation levels."

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Nuclear power is a controversial topic and everyone is biased, especially IAEA, but even WHO. The author of the book that claims that 985,000 people have been killed by Chernobyl is also biased. I too am biased. However, I have no association with the nuclear industry and I don't personally know anyone that died because of the Chernobyl disaster.

That being said, I feel like all the answers up until this point has been very one-sided. The number 985,000 is based on a scientific study and I found it peculiar that no one addressed the study presented in this book. In order to be able to criticize a number you need to know what it's based on, right?

I did some digging and actually found the book freely available as pdf:

Chernobyl: Consequences of the Catastrophe for People and the Environment

It's 349 pages, so I didn't read all of it and I certainly don't have time to make a full review. I found this Wikipedia article about the book where they present the following quotes from reviews of the book:

"The introduction addresses the issue of why assessments of health effects from Chernobyl are so disparate. The authors disparage the approach favoured by the majority of the epidemiology community, which seeks a correlation of health effects with levels of contamination or dose. They believe this approach is ‘impossible’ due to lack of measurements in the first few days, lack of information on ‘hot spots’ and lack of information on all of the isotopes involved."

"They consider that the USSR authorities distorted links between health effects and radiation exposure and they prefer therefore to rely on what they consider are independent investigations of comparative health measures in various territories that they consider are identical in terms of ethnic, social and economic characteristics and differ only in the exposure to radiation."

George Monibot comments on that review:

A devastating review in the journal Radiation Protection Dosimetry points out that the book achieves this figure by the remarkable method of assuming that all increased deaths from a wide range of diseases – including many which have no known association with radiation – were caused by the Chernobyl accident. There is no basis for this assumption, not least because screening in many countries improved dramatically after the disaster and, since 1986, there have been massive changes in the former eastern bloc. The study makes no attempt to correlate exposure to radiation with the incidence of disease.

However, his comment is disputed:

The fact of deliberately choosing control groups which they judge not to have been exposed for the purpose of comparison appears to contradict Monbiot's assertion that Yablokov simply assumed all increased deaths were caused by the Chernobyl accident. The review states that excess deaths recorded in the unexposed areas cited in the book were not alleged by Yablokov to be caused by the Chernobyl accident.

Another Wikipedia article stated that:

Between 1986 and 1992, it is thought between 600,000 and one million people participated in works around Chernobyl and their health was endangered due to radiation. Because of the dissolution of the USSR in the 1990s, evaluations about liquidators' health are difficult, since they come from various countries (mostly Ukraine, Belarus and Russia, but also other former Soviet republics). Furthermore, the government of Russia has never been keen on giving the true figures for the disaster, or even on making serious estimates. However, according to a study by Belarusian physicians, rate of cancers among this population is about four times greater than the rest of the population. All the figures quoted by various agencies are controversial

I included the last quote just to point out that things like increased cancer rates in these areas are likely due to the Chernobyl disaster. However, it's hard to prove that a particular individual got cancer because of Chernobyl and not due to other causes.

I think the main difference between WHO's report and Yablokov's is that WHO only counts deaths that is proven to be directly caused by Chernobyl, while Yablokov includes deaths that are statistically likely to have been caused by Chernobyl.

My conclusion is that 985,000 is plausible, but so is 4000 and there is no way of knowing the actual number. I understand that it's in IAEA's best interest to have the public believe that nuclear power is safe and thus only include deaths confirmed to have been caused by radiation from Chernobyl. Likewise I understand that Yablokov has the opposite agenda and thus includes deaths that can't be directly linked to Chernobyl.

In the end I think it's all about the criteria for attributing deaths to the Chernobyl disaster. If you die from cancer two years before you otherwise would have because of Chernobyl, is your death to be attributed to Chernobyl?

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The problem is that Wikipedia is a totally inadequate source in this regard. Case in point: another Wikipedia site claims that cancer incidence is not higher in the liquidators than in the general population. I still appreciate your posting because the discussion so far has been very one-sided and doesn’t, to my knowledge, reflect the breadth of the scientific dispute, with almost all answers exclusively relying on the conservative estimates. –  Konrad Rudolph Apr 13 '11 at 15:24
    
@Konrad, I agree that Wikipedia is an inadequate source, but I'm not an expert in this field and I didn't have the time to search for proper sources. I just felt like the discussion was too one-sided and that something had to be done about that. –  Erik B Apr 13 '11 at 15:35
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I'm having a bit of a problem following the argument here. Is the source that claims 985.000 deaths agreeing with the "between 600,000 and one million people participated [...] and their health was endangered due to radiation"? Because that means that the mortality in that group was somewhere between 98.5% and 163% ! –  MSalters Apr 14 '11 at 8:30
    
@MSalters Those numbers are unrelated. "between 600,000 and one million people" refers to the liquidators, while 985,000 refers to everyone around the globe that Yablokov et al. think died because of Chernobyl. –  Erik B Apr 15 '11 at 7:54

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