Time we learned to love radiation, say scientists

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For the past 60 years, the world has had only one response to radiation - fear. The atom bombs dropped on Japan followed by four decades of the cold war with the threat of nuclear obliteration have seen to that.

The idea of radiation as a killer is lodged firmly in the public mind. It takes only a train-load of nuclear waste - one travelling from France to Germany recently drew 3000 protesters - to spark another scare.

There is one thing everyone knows about radiation: avoid it at all costs.

But some scientists think we need to learn to love radiation, and evidence is accumulating to back their view. As Bob Bury, a consultant radiologist at Leeds Teaching Hospitals, says: "Stop worrying - radiation is good for you."

The former radiation protection spokesman for the Royal College of Radiologists, who has written a public information leaflet on radiation hazards, says his mission is to restore perspective to the radiation debate.

We know radiation destroys living things at high levels - on that there is scientific consensus. What about at low levels? Conventional thinking is that it is still damaging, but less so.

For 60 years, the official view has been that there is a linear relationship between the amount of radiation exposure and the damage done.

But some scientists question this view, and suggest radiation exposure actually follows a J-shaped curve, with small amounts conferring benefits up to a threshold beyond which it starts to be damaging.

One striking piece of evidence for this comes from radiologists themselves. They spend their professional lives exposed to radiation, in the form of x-rays and computed tomography (CT) scans, so you might expect them to have higher rates of cancer. But they don't. They have less cancer and they live longer than physicians in other specialities.

With modern safety measures, the actual dose received by radiologists is only slightly higher than for the general population. But that may be enough to give them an advantage.

So how could radiation have a beneficial effect? There is good scientific evidence that while high doses destroy cells, low-dose radiation stimulates the DNA to repair mechanisms that are essential to maintaining cells.

Low-dose radiation is also thought to lower the number of free radicals in the cell, substances which damage DNA. As well, radiation stimulates apoptosis - the process which causes damaged cells to self-destruct and die before they can become malignant and cause cancer.

The idea that small doses of radiation may be good for us is known as radiation hormesis. If proved, it would have major implications for policy.

"The radiation protection industry may be depriving radiation workers and the public of this protective effect by setting dose limits that are too low," says Bury.

Among the most prominent proponents of the theory was Professor John Cameron of the University of Florida, who died in 2005, the same year a paper summarising his views was published in the British Journal of Radiology.

He said billions of our cells were bombarded daily by natural background radiation, much of it from the radioactivity we carried naturally in our bodies, and yet despite this huge amount of radiation damage, cancer was a disease primarily of the elderly.

He suggested low-dose radiation might function as an "essential trace energy", similar to trace elements in the diet which, though toxic in large amounts, were essential to health.

Evidence for this comes from the cancer map of the United States.

The annual level of natural background radiation is more than three times higher in the Rocky Mountain states of Idaho, Colorado and New Mexico than in the low-lying Gulf Coast states of Louisiana, Mississippi and Alabama. Yet the cancer death rate is higher in the Gulf states.

So convinced was Cameron of the beneficial effects of low-level radiation that he argued there was now ethical justification for a clinical trial.

He proposed seeking volunteers over retirement age in the Gulf states, where background radiation was low, half of whom would be given a box containing a radioactive source to keep under their beds.

After 10 years, cancer rates in the "treated" group - those given the boxes - and "untreated" groups could be compared - and it was Cameron's expectation that cancer rates in those exposed to the radioactive boxes would be lower.

The idea is too radical ever to win ethical approval, but it stands as a challenge to conventional thinking.

Conventional thinking needs challenging because it is often driven by irrational fear. The public loathes the nuclear industry because of its links with the atom bomb, and fear persists despite the opportunities the industry offers for producing clean energy in the era of climate change.

Today, Britain's nuclear industry contributes about 0.2 per cent of the total annual population dose, while 50 per cent is delivered by medical x-rays and imaging (CT scans).

Glowing with health

A study of British radiologists in 2003 showed those who entered the profession between 1955 and 1970 had a 29 per cent lower risk of cancer (though this was not statistically significant) and a 32 per cent lower death rate from all causes (which was statistically significant) than other physicians.

A similar study in the United States compared workers servicing conventionally powered and nuclear-powered ships. Significantly lower death rates were found in the nuclear workers compared with the others.

The reason behind these figures may be that small doses of radiation are good for us. High doses destroy cells, but low-dose radiation stimulates the DNA to repair mechanisms that are essential to maintaining cells throughout the lifetime of the organism.

- Independent