Sir, - I write in reply to Mr Jack Eising's letter (May 9th) regarding my recent "Science Today" column on the subject of the Chernobyl accident.
First of all, let me say plainly that I am not in favour of the nuclear industry. I am therefore neither consciously nor unconsciously sifting out evidence that will minimise the effects of the Chernobyl accident. I accept that this accident had terrible consequences in the former USSR, but what I am trying to tease out is what fraction of these consequences can be attributed to radiation. it is important to know this for reasons I will return to later.
Mr Eising wonders where I get my information regarding health effects of the radioactive fallout in the former USSR. My main sources of information are (a) The Ninth International Congress on Radiation Protection, Vienna, 1996 (which I attended); (b) the international conference "One Decade after Chernobyl", Vienna, April, 1996 (organised by the EU, international Atomic Energy Agency and WHO); (c) The WHO Report on The Health Effects of the Chernobyl Accident, (WHO, 1995); (d) various papers in scientific journals (too numerous to list).
Mr Eising questions my report of the estimate that radiation from the accident may cause an extra 5,000 fatal cancers in the former USSR over the next 70 years, and he contrasts this with reports of much larger numbers of deaths that have already occurred amongst the Chernobyl "liquidators".
But it is difficult to know what to make of the reports concerning the "liquidators". A statistical misunderstanding complicates this issue of the 600,000 people engaged in clean up operations ("liquidaturs"), it has been reported that 7,000 to 10,000 have died within four years. This sounds dramatic. However, in a population of 600,000 healthy people in western Europe, aged between 35 and 40 years, approximately 7,000 would die in any four year period. It is, therefore, inappropriate to invoke radiation alone to explain the Chernobyl figure. Of course radiation may have been involved in some of these deaths, but if so, probably only in a small minority.
As regards cancers, the scientific consensus is that, apart from thyroid cancer, there has been no statistically significant increase in rates of other cancers attributable to radiation in the former USSR. Increased rates of these other cancers may be detected in the future, although this would seem unlikely since no trend is apparent at this stage. The Chernobyl radiation will cause some excess non thyroid cancers over the next 50 years. But when such numbers are small it is impossible to detect them in the high background rate of spontaneous cancers (25 per cent of people get cancer from all causes).
it is important to accurately understand the risks attributable to radiation in order to choose appropriate protective measures in the event of radioactive fallout, e.g., what levels of radiation call for handing out iodine tablets, what levels call for evacuation of an area, etc? Such protection measures have negative effects in themselves, and should only be invoked when their benefits exceed their risks.
For example, evacuating people from their homes and areas is extremely stressful for them. This stress is very bad for health.
A serious accident in the UK nuclear industry could deposit radioactive fallout on Ireland. If this happens we will be very badly served if we have so oversensitised our Government to the dangers of radiation that they prescribe inappropriate precautions that would, in themselves, have more severe consequences than the radiation itself. - Yours, etc.,
University College, Cork.