Friends of the Earth, Australia

Anti-Nuclear and Clean Energy Campaign

Last updated 21 October 2008.

Introduction
Linear no-threshold risk model
Committee on the Biological Effects of Ionising Radiation
Misinformation arising from methodological problems
References

Updates

Introduction

The weight of scientific opinion holds that there is no threshold below which ionising radiation poses no risk.

Radiation protection agencies establish dose limits for radiation exposure from nuclear facilities but there is no pretence (from radiation protection agencies, at least), that radiation doses below these levels are without risk.

Moreover, as scientific understanding of the effects of ionising radiation has advanced, permitted dose limits have been dramatically reduced. For workers, the permitted dose has decreased by no less than 2500%:
* 500 millisieverts (mSv) p.a. in 1934
* 150 mSv in 1950
* 50 mSv in 1956
* 20 mSv (averaged over five years) in 1991.

In Australia, the maximum permitted dose is 1 mSv for members of the public (in addition to background radiation which is typically of the order of 2 mSv p.a.)

Linear no-threshold risk model

Radiation protection agencies around the world, including the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA), all base regulations on the linear no-threshold model which assumes that there is no threshold below which radiation exposure is safe.

Notwithstanding growing scientific confidence in the linear no-threshold model, uncertainties will always persist. In circumstances where people are exposed to low-level radiation, epidemiological studies are unlikely to be able to demonstrate increased cancer rates because of the 'statistical noise' in the form of widespread cancer incidence from many causes, as well as other methodological difficulties.

A report from the Committee on the Biological Effects of Ionising Radiation (BEIR 2005) illustrates the difficulty. It estimated that one out of 100 people exposed to 100 mSv of radiation over a lifetime would probably develop cancer as a result of that exposure, but that 42 cancers can be expected in the same group from causes other than radiation exposure. A 2.4% (1/42) increase would not register as a statistically-significant increase. Radiation exposure from nuclear facilities is typically far less than 100 mSv which makes it far less likely that a statistically-significant effect will be demonstrated.

The methodological difficulties are addressed by Dr Sue Wareham (2007):

"Firstly, health effects such as cancer due to radiation exposure often take decades to develop. Secondly, cancers due to radiation exposure are indistinguishable from any other cancer. Thirdly, radioisotopes can travel great distances. Therefore epidemiological studies investigating the effects of a particular radiation exposure are necessarily very long, they may involve many countries if not continents, and they are extraordinarily complex.

"Add to this the fact that cancer is a common disease in any event, and the result is that a small percentage increase in cancer rates due to radiation exposure can readily be overlooked, even when the absolute number of cancers caused by radiation exposure may be very large.

"A further source of misleading research results is the mixing, inadvertently or knowingly, of data for populations exposed to quite different levels of radiation, for example after a nuclear accident. The results for heavily exposed populations may then be 'diluted' by results for much less exposed populations and the results overall will appear reassuringly low."

Numerous studies have demonstrated a statistically-significant increase in cancer incidence around nuclear plants, but they are generally dismissed by the nuclear industry, often on spurious, methodological grounds.

An important issue is the onus of proof -a difficult issue at the best of times, all the more so given the difficulty of demonstrating statistically-significant effects from low-level radiation exposure.

Committee on the Biological Effects of Ionising Radiation

Notwithstanding the methodological problems, there is growing scientific confidence in the linear no-threshold model. An important recent study was the 2005 report of the Committee on the Biological Effects of Ionising Radiation of the US National Academy of Sciences (BEIR 2005). The BEIR report comprehensively reviewed available data and supports the linear no-threshold risk model.

The BEIR Committee stated:

"The Committee judges that the balance of evidence from epidemiologic, animal and mechanistic studies tend to favor a simple proportionate relationship at low doses between radiation dose and cancer risk."

"... the risk of cancer proceeds in a linear fashion at lower doses without a threshold and ... the smallest dose has the potential to cause a small increase in risk to humans."

Richard Monson, Chair of the BEIR Committee and professor of epidemiology at the Harvard School of Public Health, said:

"The scientific research base shows that there is no threshold of exposure below which low levels of ionizing radiation can be demonstrated to be harmless or beneficial. The health risks - particularly the development of solid cancers in organs - rise proportionally with exposure. At low doses of radiation, the risk of inducing solid cancers is very small. As the overall lifetime exposure increases, so does the risk."

The 2005 BEIR report noted that uncertainty remains because of the unavoidable methodological difficulties:

"It should be noted however, that even with the increased sensitivity the combined analyses are compatible with a range of possibilities, from a reduction of risk at low doses to risks twice those upon which current radiation protection recommendations are based."

Misinformation arising from methodological problems

The difficulty of demonstrating health impacts from low-level radiation exposure is used by nuclear proponents as the basis for an endless stream of self-serving, disingenuous and scientifically-indefensible statements.

For example, ANSTO states:

"Radiation effects may appear following exposure to large amounts of radiation ... it would take a very large dose to kill sufficient numbers of your cells to cause your death ... typically several thousand times as large as the radiation dose you receive normally each year from the environment. Note also that to cause your death, you would need to be exposed more or less in one hit, not spread out over a year. (Compare with sunlight: spread out over a year it gives you a suntan, but in one day of sunbaking it could cause your death by sunstroke.)" (ANSTO, 'Ionising Radiation' pamphlet.)"

The following Q&A illustrates a variation in which ANSTO wants to have its yellowcake and eat it too, claiming that low-level radiation is both hazardous and safe at one and the same time:

Question. You state that radiation levels from low-level waste are "minimal and safe", implying that there is no risk from low-level radiation. Is that ANSTO's view? If so, how does ANSTO reconcile that view with the weight of contrary scientific opinion, e.g. as expressed clearly in the 2005 BEIR report?

ANSTO: The statement made was that radiation levels from low-level waste are minimal and safe. That does not imply there is no risk, it implies the risk is minimal and below the level that would be of any safety concern. Radiation levels are set by regulatory bodies based on recommendations from ICRP, to which groups such as BEIR contribute, to ensure that both workers and the public can be assured of a safe environment. (ANSTO Chief of Operations, 20/6/07).

The industry-funded Uranium Information Centre (UIC-1) ignores predicted deaths from low-level radiation to claim that nuclear power is far safer than alternative energy sources including hydro. Yet the United Nations Scientific Committee on the Effects of Atomic Radiation (1994) estimated the collective effective dose to the world population over a 50-year period of operation of nuclear power reactors and associated nuclear facilities to be two million person-Sieverts. Applying the standard risk estimate to that level of radiation exposure gives an alarming total of 80,000 fatal cancers. Of course, applying risk estimates (with their uncertainties) to dose estimates (with their margin of error) is less than precise. But the nuclear industry's solution - to pretend that its emissions have no impact whatsoever - is dishonest.

Likewise, the UIC ignores cancer deaths from routine nuclear fuel cycle emissions to state that: "The risks from any conceivable nuclear plant (advanced reactor type) in Australia would be even less than those from other Western plants operating worldwide since the 1960s, which have not caused any loss of life in almost 12,000 reactor years of operation." (UIC-2)

Likewise, the UIC states: "Low levels of radiation comparable to those received naturally in some places (up to 50 mSv/yr) are not harmful." (UIC-3)

And to give one further example, the UIC states: "According to authoritative UN figures, the Chernobyl death toll is 56 (31 workers at the time, more since and 9 from thyroid cancer)." (UIC-3) In fact, a 2005 UN report estimates the total death toll at about 9,000, with a large majority of the fatalities arising from exposure to low levels of radiation, and there are credible scientific studies estimating a far greater death toll. Using a standard risk estimate from the International Commission on Radiological Protection (0.04 cancer deaths per person-Sievert of low-dose exposure to ionising radiation) and the International Atomic Energy Agency's (1996) estimate of total exposure (600,000 person-Sieverts) gives an estimated 24,000 cancer deaths from Chernobyl.

References

BEIR 2005 - National Research Council (of the US National Academy of Sciences), 2005, “Health Risks from Exposure to Low Levels of Ionizing Radiation (BEIR VII - Phase 2)”, written by the NRC’s Board on Radiation Research Effects, <www.nap.edu/books/030909156X/html>, <www.nap.edu/catalog/6230.html>)

International Atomic Energy Agency, 1996, "Long-term Committed Doses from Man-made Sources," IAEA Bulletin, Vol.38, No.1.

United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), 1994, "Ionising Radiation: Sources and Biological Effects", New York: UNSCEAR.

UIC-1 <www.uic.com.au/nip14.htm>

UIC-2 <www.uic.com.au/nip44.htm>

UIC-3 <www.uic.com.au/nip43.htm>

Wareham, Sue, 2007, EnergyScience Coalition Briefing Paper #20, <www.energyscience.org.au>.

Updates

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Snippet from

Reasonable Doubt  April 24th, 2008
Publication Date:
04/24/2008
Source Link: New Scientist
<www.rachel.org/en/node/6958>

Studies in the 1980s revealed increased incidences of childhood leukaemia near nuclear installations at Windscale (now Sellafield), Burghfield and Dounreay in the UK. Later studies near German nuclear facilities found a similar effect. The official response was that the radiation doses from the nearby plants were too low to explain the increased leukaemia. The Committee on Medical Aspects of Radiation in the Environment, which is responsible for advising the UK government, finally concluded that the explanation remained unknown but was not likely to be radiation.

There the issue rested, until a recent flurry of epidemiological studies appeared. Last year, researchers at the Medical University of South Carolina in Charleston carried out a meta-analysis of 17 research papers covering 136 nuclear sites in the UK, Canada, France, the US, Germany, Japan and Spain. The incidence of leukaemia in children under 9 living close to the sites showed an increase of 14 to 21 per cent, while death rates from the disease were raised by 5 to 24 per cent, depending on their proximity to the nuclear facilities (European Journal of Cancer Care, vol 16, p 355).

This was followed by a German study which found 14 cases of leukaemia compared to an expected four cases between 1990 and 2005 in children living within 5 kilometres of the Krummel nuclear plant near Hamburg, making it the largest leukaemia cluster near a nuclear power plant anywhere in the world (Environmental Health Perspectives, vol 115, p 941).

This was upstaged by the yet more surprising KiKK studies (a German acronym for Childhood Cancer in the Vicinity of Nuclear Power Plants), whose results were published this year in the International Journal of Cancer (vol 122, p 721) and the European Journal of Cancer (vol 44, p 275). These found higher incidences of cancers and a stronger association with nuclear installations than all previous reports. The main findings were a 60 per cent increase in solid cancers and a 117 per cent increase in leukaemia among young children living near all 16 large German nuclear facilities between 1980 and 2003. The most striking finding was that those who developed cancer lived closer to nuclear power plants than randomly selected controls. Children living within 5 kilometres of the plants were more than twice as likely to contract cancer as those living further away, a finding that has been accepted by the German government.