Madam, - Although Tim O'Brien (March 27th) may well have reported accurately what he heard at the Louth County Council meeting with experts from British Nuclear Fuels Limited (BNFL), we believe that your readers will almost certainly have been misled by his report. They should be aware of the following:
Iodine tablets were issued not only for use in the aftermath of an accident at Sellafield but also in case of accidents at nuclear reactors elsewhere.
Some of these reactors are much closer to us and contain much larger inventories of radioactive iodine than did the Calder Hall reactors on the Sellafield site. The shutting down for good, a year ago, of those reactors does not mean that we no longer need protection - as would be provided by the tablets - against the possible contamination of our thyroid glands.
Iodine tablets are effective against all kinds of radioactive iodine, not just iodine-131 as was reported. This includes radioactive iodine-129 which is still present in the spent fuel at the Sellafield fuel reprocessing plant.
The likelihood of an adverse effect from taking a tablet at the time of an accident is tiny and is outweighed by the collective protective effect. This was the experience in Poland in the aftermath of the Chernobyl accident.
A simpler, safer and healthier solution, previously advanced by us in The Irish Times (29/10/01), by which a population at risk could be given a degree of protection against the effects of radioactive iodine uptake would be to increase dietary iodine intake. This course has the advantage of providing a degree of protection in advance of a nuclear accident and is not susceptible to the panic which would inevitably accompany a nuclear emergency.
A feature of the Chernobyl accident was the relative dietary iodine deficiency of the populations living around the reactor in Belarus, Ukraine and Russia, resulting in iodine-deficient thyroid glands taking up greater amounts of radioactive iodine. The most effective method of achieving iodine sufficiency recommended by the WHO is iodisation of table salt.
Consumption of table salt would not have to change, only minor alterations to the production of salt would have to be effected.
Unlike the practice in some other countries, iodisation of table salt in Ireland is not mandatory and recent figures suggest that only 2 per cent of salt sold in the Republic of Ireland is iodised. Increasing dietary iodine intake would have the added benefit of protecting against the potentially damaging effects of mild iodine deficiency in pregnant mothers and their babies, which can result in diminished IQ and learning capacity.
It is to be hoped that the Department of Health, by considering iodine prophylaxis, will build on the success of its earlier proactive response to a potential nuclear threat and not be swayed by the aforementioned report. - Yours, etc.,
PETER SMYTH Ph.D, Iodine Study Unit, Conway Institute of Biomolecular and Biomedical Research, UCD, Dublin 4;
FJ TURVEY, Radiation and Environmental Science Centre, DIT, Dublin 2.