IS A known health risk automatically also a genuine danger? While a risk - no matter how small - is always a risk, whether it is a danger depends on our perception of hazards.

People were rightly unhappy about the radiation brought to Ireland after the Chernobyl accident, and on average we all endure an exposure of 100 microsieverts of radiation a year because of it. The statistical risk associated with this suggests that four deaths will occur here over the next 65 years as a result of this exposure.

We immediately recognise Chernobyl as a danger to us but a return flight to New York will also expose us to 100 microsieverts of radiation, this in a matter of a few hours. Yet we don't view air travel as a danger unless we are phobic about flying.

We immediately recognise the waste of money associated with a 200-1 long shot bet that Margaret Thatcher could become the next Taoiseach, yet more than a million of us queue each week without question to put our pound down on a Lotto win, nothing short of a 5.2 million to one long shot for an outright win.

For Irish people most at risk from the Sellafield nuclear reprocessing plant in Cumbria, there is a 5.25 million to one chance of dying in any given year from its radiation, yet we perceive its danger as very real and immediate.

Dr Philip Walton, professor of applied physics at University College Galway was not impressed by the latest research from Bristol University that suggested a possible cancer risk associated with electric power.

He contrasts the four possible lifetime deaths caused by Chernobyl radiation with Ireland's actual 460 road deaths per year or the 1,500 lung cancer deaths here per year.

He argues that if there is a health risk associated with the electromagnetic fields produced by overhead power lines then it must be very small indeed to be so very difficult to find and quantify.

An increased risk of death of one in a million is caused by the following:

. two days spent in New York

. smoking 1.4 cigarettes

. spending one hour in a coal mine

. driving for 400 miles on US roads