Sunday, August 8, 2010

New Scientist on the over-hyped dangers of radiation

The nuclear bombs dropped on the Japanese cities of Hiroshima and Nagasaki in August 1945 provide us with the data we need. About 66 per cent of the original inhabitants of the two cities survived to 1950, since when their individual health records have been extensively studied.

By 2000, 7.9 per cent of them had died of cancer, compared with 7.5 per cent expected from rates found in similar Japanese cities over the same period (Radiation Research, vol 162, p 377). This shows that the extra risk caused by radiation is very small compared with the background cancer risk, and less than the 0.6 per cent chance of an American citizen dying in a road traffic accident in 50 years.

Not surprisingly, those who received higher doses developed more cancers. But those subjected to doses less than 0.1 sievert showed no significant increase in solid cancers or leukaemias. Nor did they suffer an increase in the incidence of deformities, heart disease or pregnancy abnormalities. So there is a practical threshold of 0.1 sievert for any measurable effect due to a single acute dose.

Given what we now know, from radiotherapy to the legacy of the attacks on Hiroshima and Nagasaki, it is clear that radiation safety limits are far too conservative. Evidently, our bodies have learned through evolution to repair or eliminate damaged cells, with a low failure rate. I suggest the upper limit might be reset at a lifetime total of 5 sieverts, at no more than 0.1 sievert per month. That would be a fraction of a radiotherapy dose, spread over a lifetime.

Full article here.

Posted via email from Garth's posterous

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