In his book "Radiation and Reason" Wade Allison explains, in simple terms and without using fancy maths, how radiation affects life. Wade is a Professor of Physics at the University of Oxford with 40 years experience of teaching these things. You can examine the evidence and make up your own mind by buying and reading the book:

Download ($10 in own currency) Kindle edition here Purchase, or ePub edition here Purchase.

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Learn more about radiation, download free sample chapters, further details, post-Fukushima updates, etc.

(Here is an 2006 video "Myths lies and downright stupidity" by Stossel with the same message.)

Below are examples of questions that the book answers in simple straightforward terms as part of a coherent scientific story.

What is radiation?

Radiation is just energy on the move. It is generally quite harmless unless exceptionally intense. This is just as true of nuclear radiation as it is for music and sunshine, forms of radiation that we enjoy.

What kinds of radiation can cause cancer?

There are two kinds of radiation. Non-ionising radiation (as in radio waves, MRI and radiant heat) cannot break DNA bonds and cause cancer, although at extreme levels it can kill cells by cooking, as in a microwave oven. Ionising radiation can disrupt DNA bonds and cause cancer, but nature has evolved many overlapping levels of protection so that this very rarely occurs.

Should you worry about radiation from mobile phones?

No, not at all. Such radiation cannot break DNA bonds. If it was very intense, you would get hot and eventually cook - but you would feel that in plenty of time. When you warm your feet in front of the fire at home, you are enjoying much more intense radiation than you get from a mobile phone.

Does an MRI scan cause cancer?

No. An MRI scan uses radio waves, quite different to the ionising radiation used in a CT scan or simple Xray.

How safe is a CT scan?

A typical CT scan involves a radiation dose 20 times lower than the smallest dose that caused cancer at Hiroshima. This is because of the amazing protection mechanisms provided by the biology of life.

Can you feel nuclear radiation?

Not consciously, but the cells of the human body detect radiation by themselves. They repair any damage and communicate with one another establishing their defences. Nature is marvellous indeed. It can also be detected with a modern cheap meter the size of a credit card - at least, it would be cheap if mass produced. A domestic smoke detector uses a radiation detector - as cheap as finding burnt toast!

Is it safe to have several radiation scans?

Yes. You would need to have many within a few days of one another before you incurred a significant risk.

How safe is an isotope scan? How safe is nuclear medicine?

An isotope scan, like a CT scan, involves a dose of ionising radiation at a level about 20 times lower than the minimum level for which any cancer due to radiation was found at Hiroshima. So that is quite safe. This procedure is sometimes called nuclear medicine, because the patient receives an injection of an isotope of fluorine or technetium.

Who can you trust to tell you about radiation?

We need radiation and its technology for medical health and for other civil applications, especially if we are to reduce the threat of global warming. So being too cautious is no way to live. Trust your doctor and radiologist, although they may not know much about power stations. Radiation from these is far, far lower than your radiologist may advise for your health - and for which you may be thankful. Read the book “Radiation and Reason” to learn more.

Why are people frightened of nuclear radiation?

Ah, well, that is a matter of more than half a century of political and social history! During the Cold War everyone was frightened, not just of the explosion of a nuclear weapon, but of the effect of the radiation and the residual radioactivity. Now that we know more biology and have adequate data, we need no longer be so over-awed by messages of “WMD” or “45 minutes”. International politics is a dirty business but that has always been so.

What is a realistically safe level of risk?

A whole-of-life mortal risk of 1 in a 1000 corresponds to a loss of two weeks of life expectancy, on average. That is less than the chance of death from a road traffic accident and, given in a good cause like saving the environment for your children and grandchildren, that seems a sensible bet. Choose your own number, but be realistic. One in a million is only 20 minutes of life - the environment is worth much more than that!

What is nuclear energy?

Energy locked into the centre of the atom. It can only escape in three ways, all of which are rare:

Does nuclear radiation make things radioactive?

No, not in practice. Only neutron radiation can make materials radioactive, and this is only found inside a working reactor – and neutrons decay away in 20 minutes.

What levels of radiation are safe, given what we know today?

Low doses (<100mSv) and doses given at low rates (<100mSv per month) with a lifetime limit of perhaps 5000mSv. These numbers are conservative. In the future, as more is learnt, they may be relaxed further, that is get larger.

Does radiation damage to your body build up over your lifetime?

We cannot say that it does not - but the effect is very low, as we know from data on people who have been irradiated. Furthermore there is evidence to show that low continuous exposures to radiation exercise the natural protection mechanisms that protect against cancers. This is confirmed with animal experiments - but no doubt there is more to be learnt. It is clear that in old age the immune system fails to protect so effectively against cancers.

Why is radiation not dangerous at low doses?

Biology is very clever. Through evolution it has learnt to repair and clean up after a low dose of radiation, using the same mechanisms that protect against chemical damage to cells. This is known from laboratory studies.

Why have the dangers of ionising radiation been so exaggerated in the past?

For five reasons, none of which apply in the same way today:

Is it safe to live in a high radon area?

Yes. This has been confirmed in a number of large scale studies. The only significant risk, apparently, is to heavy smokers.

Is it safe to live near a nuclear power station?

Yes, especially if the station is of a recent design, unlike Chernobyl. Buying such property would be a smart move because the price would be low - but not in the future, perhaps.

Is there a problem with high level nuclear waste?

No, except in so far as people are afraid of it. Nuclear waste is nasty but there is very little of it. Kept cooled and secure for some years, it may then be reprocessed to save the unused fuel. After that its long-term activity falls and it becomes rather harmless in a few hundred years (unlike much chemical waste). Reasonably secure burial, deep and dry, should suffice.

For how long should high-level nuclear waste be stored

If the waste is reprocessed, the valuable and long-lived components are extracted and can be re-used. The residue has a half-life of 30 years and its activity drops by a million in 600 years, so that it becomes more or less harmless.

What can we do with all the low level nuclear waste?

The classification of much "low level nuclear waste" is the result of an excessively cautious attitude to low levels of radiation. This paranoia is expensive and bad for the environment. Most such waste should be handled along with other industrial waste, buried or dumped at sea - the Earth's crust and the oceans are slightly radioactive anyway.

What would be the effect of a dirty bomb on a major city

Public panic would be more significant than anything else - and this would be unwarranted. Any radioactivity released would not go far and would not cause a major disaster.

What would happen if terrorists got hold of a bomb

They would use it to threaten and blackmail. What should we do? Call their bluff! It is unlikely that they could put the expertise together to use such a bomb. They would realise that chemical or biological weapons were more effective for their evil purposes. Most importantly, public opinion should be properly informed beforehand so that there is no panic.

How about some readable books on radiation?

Most traditional books on radiation are written to calm historical worries about the safety of radiation by taking an extremely cautious view. Three that do not are

How radioactive is your body, naturally?

The activity is about 7500 becquerel for the whole body, that is about 100 becquerel per kg (or litre). This comes about equally from Potassium-40, a relic left over from before the formation of the Earth some 6 billion years ago, and Carbon-14, the radioactive form present in all living things and used for dating. This internal radiation is about 0.25 mSv per year, 10% of the average annual radiation dose that the body receives. The rest comes from radioactivity in rocks, radon in the atmosphere, radiation from space and medical doses.

What would happen if you actually drank a litre of the radioactive water that TEPCO released into the sea on 4 April 2011 EVERY DAY for 3 months?

You would get the same radiation dose as from two wholebody CT scans. So no problem

How much "contaminated" food (as defined by the Japanese Regulations of April 2012) would you have to eat to get the same dose as from one CT scan?

About five tonnes in about 4 months. But that would be quite impossible! Such food is very safe indeed. This Regulation is not fit for purpose.