A chara - I am a bit puzzled as to why most radiation experts rely on data for low radiation doses obtained by extrapolation of those from high doses (Profs Walton, Mitchell and McAuley, May 31st). For instance, experts tell us that we are exposed to an average of 2.5 millisieverts (mls) of natural background radiation a year, about 1.0 mls of which is due to radon. By extrapolating from the high death rates from the radon at high levels in uranium mines (which is not disputed), the experts then find that about 200 deaths per year should result from radon in Irish homes.
However, it is observed that occurrence rates of malignancies are no greater than average in populations of certain regions of India and Brazil where radiation backgrounds are more than five times the average. Nature has evolved repair mechanisms for damage to tissues caused by non-radiation injuries and as life has evolved throughout in a background of ionising radiation it would be surprising if it had not devised mechanisms to cope with it.
Be that as it may, the evidence does indicate that data based on extrapolations are unreliable and that low levels of radiation if not beneficial, are at least harmless. Then why should one worry about radon in houses? The radon in unventilated underground uranium mines is of course, several thousand times that in Irish homes and consequently the death rates from lung cancer in miners was much higher prior to ventilation.
Whatever about the unreliability of extrapolation, it is about time that Nuala Aherne and other anti-Sellafield alarmists acknowledged that millions owe their lives or a better quality of life to radiation from materials produced in nuclear reactors and processing plants.
Hundreds of millions in Asia and elsewhere have benefited from the increase in yields of rice and cereals after mutation by irradiation, not to mention the countless applications of radiation and radioactive isotopes in other fields. Deirtear gur mairg a bhíonn rómhaoiteach as an mhaith ach is dá mhairg ná hadmhaíonn í. - Is mise,
SEÁN Ó CINNÉIDE,
Bóthar na Trá,
Gaillimh.