Japan nuclear threat: The tsunami is the bigger tragedy

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understandinguncertainty.org was produced by the Winton programme for the public understanding of risk based in the Statistical Laboratory in the University of Cambridge. The aim was to help improve the way that uncertainty and risk are discussed in society, and show how probability and statistics can be both useful and entertaining.

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This article on the perception of the risks of radiation appeared on the BBC News website: here is the original version with more links and corrections.

The apocalyptic visions of destruction brought by the Japanese earthquake and subsequent tsunami have been largely replaced in the media by reports of the struggle to control radiation from the stricken Fukushima nuclear plant. This provides a gripping narrative – a brave team battling to contain the threat, warnings of catastrophe and claims of incompetence, British families desperate to protect their children and leave the area. But perhaps the media coverage tells us more about ourselves than it does about the threat of radiation.

Psychologists have spent years identifying the factors that lead to increased feelings of risk and vulnerability, and escaped radiation from nuclear plants ticks all the boxes. It is an invisible hazard, mysterious and not understood, associated with dread consequences such as cancer and birth defects. It feels unnatural: in contrast, few in the West Country seem concerned at the natural radiation they are exposed to from the earth in the form of radon, even though is estimated to lead to over 1000 cancer deaths a year in this country. But if radiation comes from an accident and has been imposed on us unwillingly, we feel we can’t control it or avoid it.

It is therefore not surprising that the psychological effects of man-made and unintended radiation exposure, or even its possibility, are strong. Many of the thousands of servicemen exposed to A-bomb tests suffered life-long disability similar to post-traumatic stress disorder, and any effects of Three Mile Island were psychological rather than due to the minimal radiation exposure.

It has been estimated that 17,000,000 were exposed to significant radiation after Chernobyl and nearly 2000 people have since developed thyroid cancer after consuming contaminated food and milk as children [see correction of this statement at end of article]. This is very serious, but nothing like the impact that had been expected and a UN report identified psychological problems as the major consequence. And the perception of the extreme risk of radiation exposure is somewhat contradicted by the experience of 87000 survivors of Hiroshima and Nagasaki who have been followed up for their whole lives. By 1992 over 40,000 had died, but it’s been estimated that only 690 of those deaths were due to the radiation. Again the psychological effects were major.

Radiation does, however, feel acceptable when used in benign circumstances such as medical imaging. You can pay £100 and get a whole-body CT scan as part of a medical check-up [this is incorrect - a whole-body scan will set you back say £798], but it can deliver you a dose equivalent to being 1½ miles from the centre of the Hiroshima explosion – because over 70,000,000 CT scans are carried out each year, the US National Cancer Institute has estimated that 29,000 americans will get cancer as a result of the CT scans they received in 2007 alone.

Given extreme public concerns, risk communication in a crisis is vital. The accepted wisdom is for governments to be open and honest, without denial or premature reassurance, to own up to risks and uncertainties, and to keep up a constant flow of consistent information while giving people clear instructions and something to do. The crucial element is to retain trust, which is best kept by allowing an independent authority to head the process. At the start of the MMR controversy in the UK a few years ago, when parents began to fear that there might be a link between a measles mumps and rubella vaccination and a rising incidence of autism, I served on eminent medical committees whose reassuring conclusions appeared to have no effect on anybody - maybe what was really needed was David Beckham, Tony Blair and a few other notables to publicly take their children to be vaccinated.

The low point in risk communication was perhaps reached when Minister John Gummer force-fed his daughter a burger to show that British beef was safe from BSE, and the Japanese authorities do not seem to be handling it much better. The electricity company appears to be as secretive as their reputation suggested and although the Japanese media are cooperative, individuals able to follow western sources are faced with a barrage of conflicting opinions. The EU Energy Commissioner may have his own reasons for making extraordinary statements about apocalypse and imminent catastrophe, and (at the time of writing) the UK Chief Scientific Advisor Sir John Beddington has had to revise his previously optimistic assessment to include the ‘worst case scenario’ of radiation reaching Tokyo, although at a level which could be protected against.

Even under this ‘worst case’ the direct health consequences of the nuclear accident will be very small compared with the thousands already killed by the earthquake and tsunami, let alone the continued suffering of the survivors. Maybe we should wait and see what happens before we decide what lessons to learn, although The Daily Mail Science editor Michael Hanlon has already boldly claimed that ‘What has happened in Japan should in fact be seen as a massive endorsement of nuclear power’, given the unprecedented forces that confronted them. Others will use exactly the same information to reach the directly opposite conclusion.

Yesterday I asked an audience of 800 sixth-formers their opinion and, although they were pleased they weren’t in Tokyo, the majority still thought nuclear was a sensible option for future energy. Maybe the generation who know nothing of the Cold War are growing up with a different perspective on radiation.

Correction (March 18th)

I'm very grateful for being told about an advance copy of an updated report on the effects of Chernobyl. This reports an increase in the number of thyroid cancers compared to the earlier source I used in the article, and concludes that contaminated milk

"led to a substantial fraction of the more than 6,000 thyroid cancers observed to date among people who were children or adolescents at the time of the accident (by 2005, 15 cases had proved fatal). To date, there has been no persuasive evidence of any other health effect in the general population that can be attributed to radiation exposure."
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Nice graphic comparing radiation doses at http://xkcd.com/radiation/

It is a common fallacy for scientists and public officials to make risk comparisons without taking into account the balancing benefits, which is what ordinary people subconsciously try to do. The choice between two apparently equal risks, having a CT scan and living 1.5 miles from Hiroshima, is not unidimensional - the CT scan might save my life, whereas living next to an explosion gains me nothing - so they are not equal or comparable. This is why having radon in the earth (which is "home") seems less worrying than a visiting nuclear warship in port (a risk without benefit). I myself have never ceased to be amazed when I see some ardent nuclear protesters blissfully lighting up their cigarettes. But I understand how they think.

David [you may remember me as the SRA from Land Economy, attending CRASSH meetings and asking for advice about finding another job. Well, I write following accepting a post at AUT in NZ...and I love it! But back to risk perception] The standard reference in the field is Slovic, "Perception of risk", Science 17 April 1987: Vol. 236 no. 4799 pp. 280-285 DOI: 10.1126/science.3563507 which discusses these ideas in a very sensible way. By far the best part of the paper is his Figure 1 showing his scattergraph of dread. Best wishes, Robin

I'm not persuaded by risk assessments relating to unproven technologies. I'm even less convinced that such technologies are where we really must focus our efforts. The 19th and 20th Centuries were characterised by instances of technological collateral damage. From the effects of coal soot to those of DDT and ozone-destroying CFCs, the combination of globally distributed processes like road-building and those of very sophisticated science like nuclear reactors have raised pervasive questions about human quality of life, and about species diversity. The C19/20 experience is powerful evidence that technologists did not and probably could not have designed away all of the significant side effects of their inventions. One is left with very powerful anecdotal evidence that there will continue to be unforeseen side effects. Further to that are questions about whether we need most of this stuff in the first instance. For example, problems of starvation are reported as being more to do with distribution and politics than production. We don't need more food. We need more fairness. And this is an area where both science and technology have yet to come up with solutions. As the saying goes, science helps us live healthier, more productive lives, but does not help us address our seeming inability to rein in our desire for more gadgets, more wealth, more people; nor does it address the disparities created by people among people. So what I'd be interested in seeing from studies of risk is less about the predicted effects of current technologies, and more about the chance of having a coherent and stable moral system develop as a direct result of scientific activity. Is it greater than the chance of dying in a nuclear accident? Or much, much less?

This was quite a while ago and yes I agree. Tsunami is bigger threat after using nuclear. But then both of them arent good effect and no one wishes this to happen to anyone. So the best thing for the government to do is do not allow nuclear to be introduced in their country if its not for a good purpose.