Part of the anti-nuclear case is based on the false, official view that all exposure to radiation is harmful. Small quantities are good for youby Dick Taverne / August 22, 2004 / Leave a comment
Most of us assume that public policy is based on evidence. Alas, not so.
Why do green campaigners, with the notable exception of James Lovelock, reject nuclear power, which emits no greenhouse gases? Because they are frightened of accidents and of radiation emanating from nuclear power stations and nuclear waste. Their fears of radiation are not only widely shared, but they are nourished by official sources and have even become official policy. Present policies for radiation safety are based on the “linear no-threshold assumption,” which is endorsed by the International Commission on Radiological Protection. This is the assumption that even the smallest amount of radiation is harmful and may cause cancer and genetic disorders, and that the risk of harm increases proportionately with the dose. On this basis, we should aim to avoid any exposure at all. Accordingly, the standards for radiation protection set by the commission have become more exacting and the maximum exposure dose declared to be safe is continually lowered.
The standard measurement of radiation is set in terms of milliSieverts (mSv) per year. In the 1920s, the maximum dose regarded as safe was 700 mSv. By 1941, it was reduced to 70. By the 1990s, it became 20 for occupationally exposed people and 1 mSv for the general population. Some people believe that the maximum exposure dose should be lower still.
Unfortunately, far from safeguarding our health, current safety standards will almost certainly increase the incidence of cancer. The evidence shows that the effect of radiation on human health is not a linear one, but is a J-shaped curve. Exposure starts by being beneficial at low doses and only becomes harmful at higher doses. This effect is known as hormesis. A low dose of ionising radiation seems to stimulate DNA repair and the immune system, so providing a measure of protection against cancer. The benefit of low doses of radiation in treating cancer have been known for some time and are confirmed by a mass of evidence, particularly from Japan where it has been studied in detail as a result of Hiroshima and Nagasaki.
Many other examples of the hormesis effect are well known. A bit of sunshine does you good; too much may cause skin cancer. Small doses of aspirin have many beneficial effects; too much will kill you. It also appears to apply…