Radiation Risks: "It's Complicated"

By Chris Mooney | April 7, 2011 8:56 am

In preparation for Monday’s Point of Inquiry–which is on nuclear power–I’ve been learning more about this issue. As a result, while I don’t agree with Helen Caldicott, I do feel George Monbiot is being a tad too strident, and probably should have used more hedging.

Basically, there’s a reason why death estimates for Chernobyl vary widely. I find the explanation here, from Lisbeth Gronlund of the Union of Concerned Scientists, really helpful. The trick is that although the risk diminishes greatly as the amount of exposure decreases, there’s assumed to be no absolutely safe dose of radiation. This creates a situation in which, with Chernobyl, you have vast populations exposed to a tiny but non-zero dose. If you then do the math you get a large number of cancers, some of which will be deadly–but it is not like you will ever be able to point to who the victims were.

This does not provide a justification for Caldicott’s nearly 1 million deaths–but Gronlund finds that “70,000 and 35,000 are reasonable estimates of the number of excess cancers and cancer deaths attributable to the accident.” Read more here.

CATEGORIZED UNDER: Nuclear Power

Comments (10)

  1. David Smith

    This is why dental x-rays are so dangerous. Using that same math, how many people die?

    The body has certain methods — known and unknown — for dealing with radiation damage. If one has healthy lifestyle habits, that tiny but non-zero dose loses force because the body cleans up the damage naturally. Of course, if you eat, drink, or use tobacco to excess, you will overwhelm your body’s defenses and one lousy extra bit of gamma radiation might hit just right.

    This also goes for worry. Worry also depresses your body’s natural defenses. Yep, the more you worry about radiation, the more likely you will die of radiation induced cancer. So, ironically, the Union for Concerned Scientists is worse for you than all the fallout from Japan that reaches you.
    .

  2. Chris Mooney

    I know…this approach bugs me….but it certainly explains the difference in the estimates.

  3. Gaythia

    The whole issue of ‘how safe is safe enough” is indeed, very complicated. The science of risk, and human assessment of, and reactions to risk, are best explored with experts in this field such as David Ropek and Andrew Maynard.

    Andrew Maynard also has a background in physics. Some of his posts on radiation are quite useful. I think that the graphic reproduced here: http://umrscblogs.org/2011/03/20/making-sense-of-radiation-dose-an-excellent-visualization-from-xkcd-com/ is a quite effective graphic representation of radiation doses from sources people are likely to encounter in daily life as well as extreme events.

    I don’t believe that the shallow simplistic comments of #1 above should go unchallenged. Especially not the backhanded attack on the UCS. Of course stress affects health. On the other hand, I do not believe that “Yep, the more you worry about radiation, the more likely you will die of radiation induced cancer” is a statement that can be supported by medical science. Some people do engage in multiple risky behaviors. Some don’t. Some people die young, some don’t. Use of dental, and other medical x-rays are a balance between one risk and another. This is an educated decision made using the best knowledge, and the best technology, available at the time. Statistical risk analysis can tell us something about the relative probable links between individual genetics, behavior, exposures and health, but are not definitive for any particular individual. Healthy lifestyle habits are obviously a great idea, but not a surefire guarantee.

    Ignorance is not bliss. Intelligent analysis based on data and the world around us can be made. That is the purpose of science.

  4. Mike H

    The linear threshold model for radiation exposure is a broad application of the precautionary principal and therefore a philosophical argument, not a scientific one.

  5. Nullius in Verba

    The assumption that there is no absolutely safe dose of radiation is just that – an assumption, and almost certainly a wrong one. (Because of the possibility of hormesis.) The problem is that at the tiny levels we’re talking about the risk is unmeasurable, so there’s no way to put a number on it. There is no evidence to support it. Safety people naturally pick conservative limits, so they assume no zero effect to be safe and to keep it simple.

    The problem is much the same as asking about the number of bacteria it is safe to eat. In theory, a single bacterium could evade the immune system long enough to multiply beyond control and overwhelm your defences. In practice, we consume a steady background level of bacteria, our immune systems easily keep them under control, and there is some evidence that a small number of bacteria are necessary to trigger our defence and self-repair mechanisms into action – harmful bacteria are actually necessary for our health.

    And even if you assumed these tiny risks were positive, they’re so small that they are exceeded by the background risk we take in all other activities. Have you ever used a sharp knife in the kitchen? Have you ever boiled water? Have you ever crossed the road? The risks are self-evidently non-zero. And vast populations are exposed to these risks as well.

    It is one of the standard statistical tricks of junk science to present tiny risks in the most alarming way possible, with no context by which you could understand what it means. The result is we get a totally distorted view of the world around us – worrying about some totally insignificant risks, while blithely ignorant and unconcerned about more serious ones. It leads us into irrational decisions, pulled this way and that by the passing fashions of the scare industry. Radiation is a classic of the genre. May be you should try asking for some (statistically justified) error bars on those Chernobyl numbers.

  6. mason

    See the article by Chris Busby at Counterpunch. Excerpts:
    “The health effects of the Chernobyl accident are massive and demonstrable. They have been studied by many research groups in Russia, Belarus and the Ukraine, in the USA, Greece, Germany, Sweden, Switzerland and Japan. The scientific peer reviewed literature is enormous. Hundreds of papers report the effects, increases in cancer and a range of other diseases. My colleague Alexey Yablokov of the Russian Academy of Sciences, published a review of these studies in the Annals of the New York Academy of Sciences (2009). Earlier in 2006 he and I collected together reviews of the Russian literature by a group of eminent radiation scientists and published these in the book Chernobyl, 20 Years After. The result: more than a million people have died between 1986 and 2004 as a direct result of Chernobyl.”

    Busby cites “a study of cancer in Northern Sweden by Martin Tondel and his colleagues at Lynkoping University. Tondel examined cancer rates by radiation contamination level and showed that in the 10 years after the Chernobyl contamination of Sweden, there was an 11% increase in cancer for every 100kBq/sq metre of contamination. Since the official International Atomic Energy Agency (IAEA) figures for the Fukushima contamination are from 200 to 900kBq.sq metre out to 78km from the site, we can expect between 22% and 90% increases in cancer in people living in these places in the next 10 years. The other study I want to refer to is one I carried out myself. After Chernobyl, infant leukaemia was reported in 6 countries by 6 different groups, from Scotland, Greece, Wales, Germany, Belarus and the USA. The increases were only in children who had been in the womb at the time of the contamination: this specificity is rare in epidemiology. There is no other explanation than Chernobyl. The leukemias could not be blamed on some as-yet undiscovered virus and population mixing, which is the favourite explanation for the nuclear site child leukemia clusters. There is no population mixing in the womb. Yet the “doses” were very small, much lower than “natural background”. I published this unequivocal proof that the current risk model is wrong for internal exposures in two separate peer-reviewed journals in 2000 and 2009.”

    Busby discusses the International Commission on Radiological Protection (ICRP).
    “Why is the ICRP model unsafe? Because it is based on “absorbed dose”. This is average radiation energy in Joules divided by the mass of living tissue into which it is diluted. A milliSievert is one milliJoule of energy diluted into one kilogram of tissue. As such it would not distinguish between warming yourself in front of a fire and eating a red hot coal. It is the local distribution of energy that is the problem. The dose from a singly internal alpha particle track to a single cell is 500mSv! The dose to the whole body from the same alpha track is 5 x 10-11 mSv. That is 0.000000000005mSv. But it is the dose to the cell that causes the genetic damage and the ultimate cancer. The cancer yield per unit dose employed by ICRP is based entirely on external acute high dose radiation at Hiroshima, where the average dose to a cell was the same for all cells.”

    This is what Helen Caldicott described. A dose of radiation spread out over the whole body may be innocuous. But damage happens on the cellular level, where a small dose can kill a single cell or a cluster of cells and then damage the DNA of the surrounding cells. Years or decades later, a cancer may appear in a single or a few cells, but once it does, those few cells, using the many means cancer cells have to replicate at a rates far outstripping those of normal cells, can quickly grow into a dangerous tumor.

    It is apparent that, because of nuclear industry pressure and propaganda, few of the general public truly understand what’s at stake. Until Helen Caldicott called my attention to the risks of nuclear energy, I was ignorant of the above principle. I’m grateful to her for this.

  7. CNC

    Gronlund of the Union of Concerned Scientists numbers “70,000 and 35,000 are reasonable estimates of the number are just not supported by the science. The danger of ionizing radiation is way over rated. I assume his numbers are based of the Liner No Threshold (LNT) model which has no baseds in evidence below 100mSv just on conjecture. The evidence shows there are no health effect below 100mSv of exposure. There has been zero death so far from radiation and more than likley it will stay that way.

  8. http://www.xrayrisk.com has more info on radiation and cancer risk including an online calculator that lets you calculate radiation dose and estimate cancer risk from CT scans, x-rays and procedures. The site also allows users to log-in and track their imaging history.

  9. Dunc

    There is a huge difference between exposure to radiation and unprotected exposure to aerosolized or gaseous radioisotopes. This is why radiation workers wear protective clothing, and when appropriate, breathing apparatus. I’m perfectly happy to handle radioisotopes (in appropriate quantities and with appropriate safety precautions) but I don’t want to be inhaling or ingesting them at anything beyond background levels. (And even background levels can pose a risk in certain cases – radon exposure is a risk factor for lung cancer, even at low levels.) I’ve handled radioisotopes in the lab, but I washed my hands afterwards.

    The entire topic just pisses me off, because so many people refuse to distinguish between the risks of external exposure to ionising radiation, and the risks of environmental exposure to radioisotopes. The standard LNT model applies to the former, not the latter. AFAIK, we have no model for the latter.

    Yes, it’s complicated.

    NiV: there is a moral difference between risks you knowingly choose to take and can manage yourself, and risks imposed on you without your knowledge by other people.

  10. Well, sure, but you also get a few excess thousand deaths from radiation when you move from NYC to Denver, CO. And Chernobyl is a one-time accident. Plus, the “any amount of radiation is bad for you” hypothesis is at best a hypothesis.

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About Chris Mooney

Chris is a science and political journalist and commentator and the author of three books, including the New York Times bestselling The Republican War on Science--dubbed "a landmark in contemporary political reporting" by Salon.com and a "well-researched, closely argued and amply referenced indictment of the right wing's assault on science and scientists" by Scientific American--Storm World, and Unscientific America: How Scientific Illiteracy Threatens Our Future, co-authored by Sheril Kirshenbaum. They also write "The Intersection" blog together for Discover blogs. For a longer bio and contact information, see here.

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