It was 28 years ago today that Reactor 4 at the Chernobyl nuclear plant in Ukraine ruptured and ignited, sending a massive plume of radiation across Europe. Jim Green assesses the scientific evidence for how many people died as a result of the catastrophe.
Uncertain risk does not equal zero risk
Nonetheless, there is uncertainty with the LNT model at low doses and dose rates. The BEIR report makes the important point that the true risks may be lower or higher than predicted by LNT.
This point needs emphasis and constant repetition because nuclear apologists routinely conflate uncertainty with zero risk. That conflation is never explained or justified – it is simply dishonest.
The UN Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) and the International Commission on Radiological Protection recommend against using collective dose figures and risk estimates to estimate total deaths.
The problem with that recommendation is that there is simply no other way to arrive at an estimate of the death toll from Chernobyl – or Fukushima, or routine emissions from the nuclear fuel cycle, or weapons tests, or background radiation, etc.
Indeed UNSCEAR itself co-authored a report which cites an estimate from an international expert group – based on collective dose figures and risk estimates – of around 4,000 long-term cancer deaths among the people who received the highest radiation doses from Chernobyl. 
And UNSCEAR doesn’t claim that low-level radiation exposure is harmless – its 2010 report states that
“the current balance of available evidence tends to favour a non-threshold response for the mutational component of radiation-associated cancer induction at low doses and low dose rates.”
The view that low-level radiation is harmless is restricted to a small number of scientists whose voice is greatly amplified by the nuclear industry – in much the same way as corporate greenhouse polluters and their politicians amplify the voices of climate science sceptics.
In Australia, for example, uranium mining and exploration companies such as Cameco, Toro Energy, Uranium One and Heathgate Resources have sponsored speaking tours by Canadian junk scientist Doug Boreham, who claims that low-level radiation exposure is beneficial to human health.
Medical doctors have registered opposition to this dangerous quackery and collusion. 
Fifty immediate deaths
About 50 people died in the immediate aftermath of the Chernobyl accident. Beyond that, studies generally don’t indicate a significant increase in cancer incidence in populations exposed to Chernobyl fallout.
Nor would anyone expect them to because of the data gaps and methodological problems mentioned above, and because the main part of the problem concerns the exposure of millions of people to low doses of radiation from Chernobyl fallout.
For a few fringe scientists and nuclear industry insiders and apologists, that’s the end of the matter – the statistical evidence is lacking and thus the death toll from Chernobyl was just 50.
If they were being honest, they would note an additional, unknown death toll from cancer and from other radiation-linked diseases including cardiovascular disease.
But for those of us who prefer mainstream science, we can still arrive at a scientifically defensible estimate of the Chernobyl death toll by using estimates of the total radiation exposure, and multiplying by an appropriate risk estimate.
The International Atomic Energy Agency estimates a total collective dose of 600,000 person-Sieverts over 50 years from Chernobyl fallout.  Applying the LNT risk estimate of 0.10 fatal cancers per Sievert gives an estimate of 60,000 deaths.
Sometimes a risk estimate of 0.05 is used to account for the possibility of decreased risks at low doses and/or dose rates (in other words, 0.05 is the risk estimate when applying a ‘dose and dose rate effectiveness factor’ or DDREF of two). That gives an estimate of 30,000 deaths.
9,000 to 93,000 deaths across Europe
A number of studies apply that basic method – based on collective radiation doses and risk estimates – and come up with estimates of the Chernobyl cancer death toll varying from 9,000 (in the most contaminated parts of the former Soviet Union) to 93,000 deaths (across Europe).
Greenpeace – 270,000 cancers
A 2006 report commissioned by Greenpeace estimates a cancer death toll of about 93,000.  According to Greenpeace:
Read more at Chernobyl – how many died?