Ionising radiation: perhaps we have little to fear except fear itself

Off the coast of North Devon in UK there is to be built the Atlantic Array, a 238 square kilometre wind farm. The number of turbines will be 278 and will vary in height from about 180m to about 220m. The estimated power rating is 1500MegaWatts (MW). However power is not what matters; what matters is energy which is measured domestically in kWh – a kilowatt running for one hour.

Because of varying winds, the Array will have a Capacity Factor of about 34%, so energy production will be about 1500*24*365*0.34MWh per annum, approximately 4500GWh. Because of variability of power output, from zero to 1500MW, backup generation will be required in the system. Two modern gas fired 750MW generators would be required. On average they would run for two thirds of the time.

Upstream from the Array on the West Somerset coast is Hinkley Point, the site of nuclear power stations. Hinkley A operated from 1965 to 2000. Hinkley B started producing electricity in 1976, is still operative but due to close in 2016. One of the new nuclear power stations that are to be built in UK with both Conservative and Labour support in parliament, is Hinkley C. It will be rated at 3260MW. Power output will decline somewhat over time so I will assume that on average it only runs at 2900MW (but constantly); so energy output per annum will be roughly 2900*24*365 MWh: roughly 25000GWh. So the wind farm will produce less than one fifth of the energy produced by Hinkley C.

There are three sorts of power stations: base load that provide the main energy used but are inflexible; fossil fuels and nuclear are the main examples. Secondly there are peak load stations that can be brought on line very quickly. Examples are hydro and gas turbines. Thirdly there are stations that produce energy at times beyond human control; examples are wind and solar. In the absence of large and efficient storage systems, energy that is produced at the whim of nature is far less useful than either base or peaking power. In terms of usefulness Hinkley C beats Atlantic Array hands down.

But, what about radiation risks, Chernobyl, Fukushima, Three Mile Island, Hiroshima and Nagasaki? The general question is: 'how dangerous is ionising radiation?' The sharpened question becomes 'is there is any level of radiation that is not dangerous?'

The most commonly held view of radiation risks is the long accepted Linear No Threshold (LNT) theory which states that risk increases proportionately to total dose received, that risk is never zero and hence that all extra radiation, no matter how small, is dangerous. 'Academic' papers on radiation risk have a strong predilection for managing to put a sort of line of best fit through the data points. Apart from LNT a combination called 'Linear Quadratic' is sometimes used.

The paper Effect of Recent Changes in Atomic Bomb Survivor Dosimetry on Cancer Mortality Risk Estimates by Preston et al of the Departments of Statistics and Epidemiology, Radiation Effects Research Foundation, Hiroshima, discusses the effects of the official changes to methods of assessing radiation doses experienced by survivors from the Hiroshima/Nagasaki bombs. Those effects are shown graphically as shown below.

Both show Excess Cases per 10,000 people against Dose received in Sieverts Sv. In the left hand graph the congestion of data points at low doses is noticeable. The right hand graph for 'low dose range' shows more detail. I would assert that it is not possible to put any reasonable line of any shape at all through the points at doses below about 0.1 Sv. The inevitable error bars in all of the measurements compounds that assertion. The smooth graph LQ (linear quadratic 0-2 Sv) shows a determination to make the data fit a model, a model that was adduced from a much wider Dose range. The DSO2 graph highlights the futility of looking for a simple (or complex) mathematical model.

However the data points shown do not support the No Threshold theory. It seems highly unlikely that any level below 0.1 Sv was harmful.

Since the war safety limits for radiation have been drastically lowered. The twin pillars are ALARA (As Low As Reasonably Achievable) and LNT (Linear no Threshold) mentioned earlier. They are interconnected because if there is a 'threshold' level of radiation below which there are no adverse effects, there is no need for radiation levels to be kept below that level: ALARA becomes an expensive futility.

Since nuclear power/radiation issues first became significant there have been major improvements in our understanding of the effects of radiation on humans. Examples are in the use of radiation for diagnostic purposes and in its use for cancer treatments. Long term examinations of the consequences of inadvertent 'experiments' have been done for Chernobyl, Hiroshima/Nagasaki and painters of luminous watch hands. These have provided high quality data and risk analyses.

Taking Chernobyl first. The United Nations Scientific Committee on the Effects of Atomic radiation UNSCEAR publish periodic reports. In 2008 they produced UNSCEAR 2008. See volume 2 Annex D, Health effects. (www.unscear.org/unscear/en/chernobyl.htmlgives a summary; for Annex D go to bottom of Summary)

Quotations from Annex D are:

The observed health risks currently attributable to radiation exposure are as follows:

• 134 plant staff and emergency workers received high doses of radiation that resulted in acute radiation syndrome(ARS), many of whom also incurred skin injuries due to beta radiation;
• The high radiation doses proved fatal for 28 of these people;
• While 19 ARS survivors have died up to 2006, their deaths have been for various reasons, and usually not associated with radiation exposure;
• Skin injuries and radiation-induced cataracts are major impacts for the ARS survivors;
• Other than this group of emergency workers, several hundred thousand people were involved in recovery operations, but to date, apart from indications of an increase in the incidence of leukaemia and cataracts among those who received higher doses, there is no evidence of health effects that can be attributed to radiation exposure;
• The contamination of milk with I131, for which prompt countermeasures were lacking, resulted in large doses to the thyroids of members of the general public; this led to a substantial fraction of the more than 6000 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.

A general comment under the heading scientific limitations:

… there is reasonable evidence that acute radiation exposure of a large population with doses above 0.1 Sv increases cancer incidence and mortality. So far, neither the most informative study of the survivors of the atomic bombings nor any other studies of adults have provided conclusive evidence for increased incidence of carcinogenic effects at much smaller doses.

There is then an 'UNSCEAR statement';

The Committee has decided not to use models to project absolute numbers of effects in populations exposed to low radiation doses from the Chernobyl accident, because of unacceptable uncertainty in the predictions. It should be stressed that the approach outlined in no way contradicts the application of the LNT model for the purposes of radiation protection, where a cautious approach is conventionally and consciously applied.

In the context of what had gone before, the last sentence is rather peculiar. We will go along with LNT because it is a 'convention'? Since when did science have anything to do with conventionality?

Another remark in the document draws attention to the question as to whether cancers '…are due to the accident or background radiation'.

Variability in background (natural) radiation levels is another fact that may be seen as pointing to a serious questioning of the LNT model. A paper 'Very high background radiation areas of Ramsar, Iran: Preliminary Biological studies' is relevant.

Amongst other things the article gives interesting and relevant data showing wide variability in background radiation levels. Bearing in mind that 20mSv per year is the permitted level for radiation workers it is extraordinary that there is a small area of Ramsar where readings are 260mSv per year. The associated hot springs are used as health spas.

But the data for max and min figures for some countries is more important because variability ought to show up in mortality data – if LNT is correct. Examples give minimum and maximum levels in mGy per year are: India 0.18 to 9.64; Ireland 0.01 to 1.58; Germany 0.04 to 1.58; Norway 0.18 to 10.52. To my knowledge there is no evidence that demonstrates a significant variation in the incidence of radiation induced disease within any if those countries even though the variability is always much more than an order of magnitude. That appears significantly to weaken the LNT theory.

On 7/4/2011, soon after the Fukushima accident On Line Opinion put up an offering by Professor Wade Allison entitled 'we should stop running away from radiation'. He argued that modern knowledge, particularly of the way that the human body's cells repair themselves subsequent to radiation or oxidation attack, made the LNT model redundant and misleading, and that as a consequence 'safety levels' of radiation should be drastically raised. Allison is a nuclear and medical physicist at Oxford. He started out as a straight nuclear physicist and then altered direction to be involved in and expert at the applications of radiation to medicine – scanning and radiation therapy for example.

Allison published a book entitled Radiation and Reason sub titled 'the impact of Science on a culture of fear.' Partly perhaps because I previously knew nothing about radiobiology, I found it a most important book; mind changing. Allison is absolutely convinced about Climate change. Hence he sees the need to reduce fossil fuel emissions, and is convinced that by far the best way to do that is by using nuclear power.

Much of his thesis is that the body has multiple layers of protection against cell damage and that given some time to repair they will either repair themselves or die and be replaced by new cells. His background in the medical uses of radiation enables him to give examples of the doses given to patients. They are frequently monstrous – but given in separate doses to allow for repair. Radiation units are Sieverts and Grays, they are not really the same but for the purposes of this note I will follow UNSCEAR and assume that 1Sv equals 1Gy. Note that up to here all 'doses' except the two graphs have been in mSv and mGy, i.e each one thousandths of Sv and Gy. So Grays and Sieverts are big.

Allison gives the following treatments for some cancers:

• Bladder 30 doses of 2 Grays each. Given 5 times a week. Total 60 Grays.
• Breast 16 doses of 2.7 Grays each. Given 5 times a week. Total 42.5 Grays.
• Armpit 15 doses of 2.7 Grays each. Given 5 times a week. Total 40 Grays.
• Lung 36 doses of 1.8 Grays each. Given over a period of 12 days. Total 54 Grays.
• Prostate 39 doses of 2 Grays each. Given 5 times a week. Total 78 Grays.

To put these total doses into perspective, UNSCEAR subdivides doses for Acute Radiation Syndrome referred to earlier as being 'Very Severe' 6.5 to 16 Grays. All but one of those people died within a few weeks; 'Severe' 4.2 to 6.4 Grays, about a third died. So, all of the above treatments deliver, in total, vastly bigger doses than those that rapidly killed people after Chernobyl. Of course the therapy is carefully focussed on the cancer. But it seems evident that any idea that radiation damage is cumulative (like lead poisoning) is wrong.

Radiation and Reason examines the Hiroshima/Nagasaki data. Comparison of two groups, one irradiated by the bomb(s) and one that was not, showed that the extra risk of leukaemia caused by radiation per 1000 people were: for doses < 5mSv between -0.1 and 0.5; for 5 to 100mSv -0.4 to 0.2; for 100 to 200mSv -0.7 to 0.6. Only when we reach 500 to 1000mSv is the extra risk/1000 positive, being 1.0 to 2.6. Once again the idea of Linear no Threshold fails.

I find Allison's arguments generally convincing because he produces a mechanism – the repairing of cells over time – which explains how and why huge doses can be given with safety without immediate death and why the LNT model fails.

The title of this article is, with apologies to FD Roosevelt, referring to the idea that fear itself is dangerous. A final quotation from UNSCEAR 2008:…the Chernobyl accident is known to have had major effects that are not related to the radiation dose. They include effects brought on by anxiety about the future and distress, and any resulting changes in diet, smoking habits, alcohol consumption and are essentially unrelated to any actual radiation exposure.

These people have been told that they are doomed. They have been frightened by the wildly exaggerated dangers of radiation. Fear rules their lives. And we are doing the same to people from around Fukushima. But illogical fear of low level radiation is much more widespread than that. Such fear is rampant in most 'western countries'; Australia being an extreme example.

George Monbiot, environmental writer for the left wing Guardian newspaper in UK, like Wade Allison, is a passionate believer in global warming caused by CO2emissions. He sees nuclear energy as the only practical way to reduce emissions. He, rightly in my opinion, stated last year 'there are no ideal solutions. Every energy technology carries cost….the impact of Fukushima on the planet as a whole is small'.

People generally, especially those who are convinced that CO2causes climate change need to consider a few facts:

• Even a 'doubting Thomas' such as myself recognise that there is some good science supporting the fear of climatic change caused by CO2, but there is no scientific evidence that low dose radiation is a risk.
• Japanese imports and hence use of coal and oil has roughly doubled since Fukushima.
• The 'peak oil' idea is dead because of the massive rise in shale oil and gas production.
• Irrational fear of low level radiation leaves us at the mercy of any nutter group that makes a 'dirty bomb' and 'pollutes' a city with miniscule levels of radioactive isotopes.
• That fear also makes nuclear energy much more expensive – to the benefit of fossil fuels.
• 'Alternative' energy production, especially in the absence of massive and efficient storage capacity is unlikely to meet societal needs.
• Global population continues to rise very rapidly.

So we need to make up our individual and collective minds: are you more frightened of (a) climate change/acidification or (b) low dose ionising radiation?

Long ago, because of a lack of scientific knowledge, people were frightened of many things that were not real. They prayed for deliverance:

From ghoolies and ghosties and long leggety beasties and things that go bump in the night, Good Lord deliver us.

The systematic exaggeration of the dangers of low dose radiation is having a similar effect on a vast number of people today. They are frightened.

Maybe a new prayer could be devised to protect from another non-existent threat, perhaps:

From gammas and alphas and betas that eat us and neutrons that pierce us, Good Windmills deliver us.