Sir, - In her article on radiation risks (Science Today, April 18th), Nuala Ahern MEP correctly writes that natural background doses are not without health impact. She also says that, unlike the risks from man-made releases, the risks from natural background radiation are not the result of social and political processes. This is not strictly correct. The largest and most variable dose and risk from background natural radiation comes from radon exposure in our dwellings.
While the radon gas, which is produced in rocks and soils, is "natural" in origin, the high levels that can be reached in dwellings are a direct result of the way we construct and use our dwellings.
In Ireland, as in most EU countries, the control of high radon levels in new dwellings is now part of our building regulations.
Ms Ahern quotes an estimate by the UK National Radiological Protection Board that natural background radiation results in about 6,000 to 7,000 cancer deaths a year in the UK. I will not comment on the quoted UK figures but on the basis of current scientific evidence it can be conservatively estimated that exposure to radon in Irish dwellings may be implicated in about 250 cancer deaths a year. While such estimates have large uncertainties and are almost impossible to verify, it is clear we are not dealing here with trivial risks. The interest of environmentally concerned politicians, such as Nuala Ahern, is therefore be most welcome. - Yours, etc.,
JAMES P. McLAUGHLIN,
Natural Radiation
Research Group,
Department of
Experimental Physics,
UCD,
Dublin 4.