Are the health dangers from nuclear radiation exagerated?
17 Mar, 2010 02:04 pm
The debate about the risks to human health of exposure to nuclear radiation has been rekindled. Two new books, one British and the other American, have contributed to this.
Both books challenge the conventional wisdom about the risks to human health of exposure to radiation and their conclusions have important consequences for the two most serious global problems facing us today – minimizing climate change and preventing the further spread of nuclear weapons.
The books are topical because we are on the threshold of a nuclear renaissance, in which many more nuclear-power reactors will be operated for electricity generation, exposing populations to greater amounts of nuclear radiation, and because President Barack Obama is arguing for the global abolition of nuclear weapons.
Atomic Obsession argues that “the toxic fear associated with radiation from nuclear weapons distorts the balance of international relations and senselessly makes enemies of friends”. Muellar argues that nuclear weapons are extremely hard to fabricate and deploy and that their destructive power are much exaggerated as are the dangers of radioactive fallout.
The damage done by the nuclear weapons dropped on
The risk of the use of nuclear weapons, even in unstable regions such as the
Radiation and Reason claims that the health risks of ionising radiation are exaggerated to such an extent that people have become irrationally fearful of radiation. This public fear, Allison says, is preventing governments from fully exploiting the use of nuclear-power reactors for the generation of electricity.
Safety levels set for nuclear energy grossly overstate the risks, he goes on, making nuclear electricity unnecessarily expensive. Because nuclear generation emits less carbon dioxide than fossil-fuelled power plants, he goes on, this weakens it as a weapon against global climate change.
Although Allison accepts the risks of high levels of exposure to ionising radiation, he argues that low levels of exposure can be tolerated by the human body and that the body can protect itself from radiation damage. In his words: “The ability to repair damage and replace cells, we discovered in the last 50 years doesn’t cause damage except under extreme circumstances”.
Mainstream scientists believe that ionising radiation can damage the body’s cells by breaking one or both strands of the DNA in them, possibly causing them to have a higher probability to become cancerous, unless the body can repair the damage or the cell is killed. Radiation is very effective at breaking both strands of DNA, the type of damage that is most difficult for the repair processes to cope with properly (3).
But what is the actual risk of damage to health from exposure to ionising radiation - for example, how many cancer deaths will occur in a group of people exposed to a certain amount of radiation? We have very little data from which to estimate this risk for low doses of ionising radiation and, consequently, we have to extrapolate from evidence at higher doses.
Risk estimates rely mainly on data from the survivors of the atomic bombings of
The points on the graph plotting the risk of a certain heath effect, like cancer, against the amount of radiation (dose) received are subject to large statistical errors. The radiation doses received by survivors were, of course, not measured when they were received. Estimates of the doses made by researchers after the war are crude, to say the least.
The graph of risk versus radiation dose consists, therefore, of a few widely scattered points, each with large error bars. Should the extrapolation from high doses (most points on the graph are for relatively high doses) to low doses be done linearly in a straight line through the zero point (the Linear No Threshold ‘LNT’ model), or sub-linearly (where low levels of radiation are relatively less harmful than for the LNT model), or supra-linearly (where low levels of radiation are relatively more harmful than for the LNT model)?
There is no general agreement about which method is likely to be the correct one; in fact, the points on the graph are so widely spaced and with such large errors that it is possible to extrapolate to low doses linearly, sub-linearly or supra-linearly – you can take your pick. Estimates of, for example, cancer risk from exposure to radiation are, therefore, very unreliable and uncertain.
Nevertheless, the general scientific consensus is for a linear extrapolation through the zero point (i.e., the LNT model) implying that all exposure to radiation, even at very low levels, carries a risk of causing damage (4). But Allison disputes the LNT model, arguing that there is a threshold dose below which the body can repair all damage done to its DNA and which is, therefore, a safe dose.
He argues that if the regulations set by the authorities, aimed at preventing people receiving low doses of radiation, are revised to take into account a threshold dose, nuclear power would be significantly less expensive. For example, nuclear-power reactors could be provided with less thick and cheaper shielding to protect workers and radioactive waste could be disposed of less expensively if workers could handle waste containers for longer times.
Discovery of previously unknown effects
Recent research has indicated two strange effects of radiation exposure. One causes damage to cells temporally remote from the cells hit by the radiation, called radiation-induced genomic instability effects (5). The other causes damage to cells spatially remote from the cells hit by the radiation, called bystander effects (6).
These effects are likely to modify the usual explanation of radiation damage, i.e., single and double breaks on the cells’ DNA. Because of them, many scientists question the validity of the risk factors currently used by the agencies regulating nuclear activities, such as the UK Health Protection Agency.
The health hazards of exposure to nuclear radiation are an emotive issue. This is hardly surprising. Ionising radiation is associated with dread diseases – among them cancers, leukemia, and genetic mutations that damage offspring.
The legacy of, for example, the 1986 nuclear reactor accident at
The danger of nuclear radiation was also highlighted by the murder of the former Russian intelligence agent Alexander Litvinenko by radioactive poisoning. This demonstrated the frighteningly high toxicity of some radioactive materials.
On 1 November 2006, Litvinenko ingested polonium-210, probably by drinking a cup of tea at a meeting at a
According to official estimates of risk, the inhalation of mere 0.06 micrograms of polonium-210 will cause a fatal cancer. And the ingestion of 0.3 micrograms of polonium-210 will cause a fatal cancer. These are minute amounts (8).
People living near nuclear-power stations are understandably concerned about the results of an authoritative recent German study, which shows that there is a large increase in leukemia risks in infants living near German reactors (9). This conclusion is supported by many other studies into increased levels of child leukemia close to nuclear power stations around the world.
Public interest in the health effects of exposure to the radiation associated with nuclear power will clearly increase as we move into a nuclear renaissance. The fact that there is no scientific consensus about the health effects of nuclear radiation enhances public concern. It is very clear that much more research should be done on the issue, and done as a matter of some urgency.
1. Wade Allison, Radiation and Reason; The Impact of Science on a Culture of Fear, Printed and distributed by
York Publishing Services, 23 October 2009, ISBN:0-9562756-1-3.
2. John Mueller, Atomic Obsession; Nuclear Alarmism from
3. UNSCEAR Report: Genetic and Somatic Effects of Ionizing Radiation. Report of the United Nations Scientific Committee on the Effects of Atomic Radiation, United
4. BEIR VII: Health Risks from Exposure to Low Levels of Ionizing Radiation, Biologic Effects of Ionizing Radiation (BEIR) reports: GEIR VII.
5. E. G. Wright, Radiation-induced genomic instability: manifestations and mechanisms, International Journal of Low Radiation 2004, Vol. 1, No.2, pp. 231 - 241.
6. Radiation bystander effects.
7. Alexey V. Yablokov,
An excellent review of studies of the deaths attributed to radioactivity released by the
8. John Harrison, Rich Leggett, David Lloyd, Alan Phipps and Bobby Scott, Polonium-210 as a poison, Journal of Radiological Protection, Volume 27, Number 1, March 2007. www.iop.org/journals/jrp
9. Rudi H. Nussbaum, Childhood Leukemia and Cancers Near German Nuclear Reactors: Significance, Context, and Ramifications of Recent Studies, International Journal of Occupational and Environmental Health, Vol. 15, No. 3 (2009).