Sir, Nuala Ahern (February 6th) is, of course, quite right that it would be most satisfactory if epidemiological research could easily elucidate the effects of radiation on human populations. Unfortunately, however, it isn't so simple.
In order to detect significant changes in effects such as cancer and leukemia, which are already present in the population, it is necessary to study a large group of people exposed to appreciable doses. The Japanese A bomb survivors are typical of such groups, and it is only alter decades of assiduous study of them that the risks of various forms of radiation induced cancer are now coming to be understood. Information about such risks is regularly published by the United Nations Scientific Committee on the Effects of Atomic Radiation, and is used extensively by scientists having responsibility in radiation protection.
The radiation doses received by any group in Ireland, together with the small sizes of the groups are simply loo low to be of any practical use in this regard. The smallest dose received by any section of the Japanese study group was 100,000 microsievert and many of them received doses much higher than this. Compare this with the annual dose of microsievert to an average consumer of fish on the Irish east coast the dose to a heavy consumer could be several microsievert.
As the Radiological Protection Institute of Ireland has emphasised, in several of its informative and excellently produced reports, such doses, though tiny, are of course nonetheless objectionable from an Irish point of view, since no benefit to Ireland results from operations such as Sellafield. The levels of contamination obviously need to be kept continually under review, but any idea of the Irish Sea becoming a dead sea is hyperbole, at least as far as radioactive contamination is concerned.
Everyone in Ireland receives about 3,000 microieverts a year invariably from all sources of radiation, natural and man made. Of this dose, slightly more than half, on average, has now been shown to come from radon. With doses of this magnitude, it is hardly surprising that much scientific effort has been put into the measurement of radon levels. In this regard. I would suggest that the RPII has its priorities absolutely right. Yours, etc., Knocksinna Crescent, Dublin 18.