Sir, - Dr Crowley (October 3rd) accuses Professor Walton of playing down the health effects of the Chernobyl accident. As Professor Walton intimated, an enormous amount of scientific effort has been put into studies of the health effects of the appalling Chernobyl accident. A recent review by John D. Boice of the International Epidemiology Institute, appearing in the Journal of Radiological Protection, cites studies by authorities such as the United Nations Scientific Committee on the Effects of Atomic Radiation, the Organisation for Economic Co-operation and Development, the International Atomic Energy Agency, the European Commission, the World Health Organisation and the US National Council on Radiation Protection. In addition, many studies have been made by national groups as well as by individual scientists.
From all this body of work, the effects that can be positively attributed to the Chernobyl accident are the deaths and injuries of firemen and clean-up workers who received lethal radiation exposures shortly after the event; a significant increase in the incidence (but not the mortality) of childhood thyroid cancer in nearby populations; and psychological effects, presumably induced by the stress following the accident (for example, clean up workers who came from Estonia showed a 50 per cent rise in suicide rate).
It needs to be emphasised that an increase in leukaemia has not been demonstrated as yet in this group; however, previous experience from detailed studies of other irradiated groups indicates that any increase in leukaemia would have been expected by now, more than 10 years since the accident. It follows that a low incidence of leukaemia at this stage makes it unlikely that an increase in other cancers could be detected.
Suggestions have been made that increased incidences of other conditions found in the Belarus region (for example, developmental effects or infections) were caused by exposures resulting from the Chernobyl accident. No such effects have been substantiated by any sound epidemiological survey yet undertaken. It may well be that these conditions, normally indigenous to that region, have been discovered during the close examination that has been made in the area since the accident. Before then, the health records there were less than ideal.
It is not "playing down" the effects to point out the actual state of current scientific knowledge about them. Indeed, it is incumbent on those who know something about the situation to explain it. The results of that frightful event are bad enough without having to be exaggerated. - Yours, etc.,
Foxrock, Dublin 18,