Review of the Handbook of Radon, as published in New Scientist magazine, 16 January 1993. Please note that some of the logic used in this review is incorrect!

A story of diminishing returns. Simon Wolff.

DOES radon, a naturally occurring radioactive gas, cause cancer and how much should we spend minimising the risk? These are two of the questions posed by Stephen Wozniak in his handbook on radon risks and their possible mitigation. Until recently; Wozniak was chief of the Building Research Establishment's radon research section but now he is reappraising the risks associated with radon.

What concerns him is that dealing with the small levels of radon in 20 million buildings in Britain costs 40 million per life saved, perhaps preventing 250 of 500 (theoretical) radon-related deaths, when government agencies are so under-funded, and tens of thousands of elderly die of hypothermia each winter.

Money, Wozniak speculates, would be more efficiently spent dealing with the 2000 homes with the highest levels of radon, at a cost of 12000 for each life so saved (in theory), or perhaps treating 80 000 of the worst-affected homes at a cost of 70 000 per life.

The Handbook of Radon aims to tackle these issues while advising homeowners, as well as architects, about practical ways of dealing with high levels of radon. Wozniak argues for cost-benefit analyses in dealing with environmental health problems but such analyses are always vexed. How much is a life worth? How do we calculate how many lives may be lost in relation to environmental health problems?

The Department of Transport, for example, estimates a life to be worth 1 million and includes a sum of 'value of life saved" in its dubious cost-benefit equations applied to the building of motorways. Nobody in their right mind believes that motorways save lives, yet these magic numbers go into the equation-2S per cent of the benefit side of motorway projects costing 10 'million per mile. By contrast, thousands die as a result of hypothermia and episodes of air pollution annually without a penny being spent in prevention.

Life is clearly priceless, but the value allotted to safeguarding its continuation is related to separate political exigencies. This, I feel, has bearing on Wozniak's complaint. The prevention of a radon-related death is becoming very expensive as more and more is spent on diminishing the effects of radon. Who benefits politically from this market in theoretical death? Perhaps it is the nuclear power industry; keen to minimise concern about industrial radiation or the building trade, which is eager to screw a little more profit out of a gullible and tremulous home-buying public. Or could it possibly be the huge lobby of road transport interests interested in distracting attention from the 10 to 15 per cent of lung cancers that cannot be attributed to smoking?

Of course, nobody has ever been shown to have died as a result of radon in homes. The National Radiological Protection Board's estimate of 2500 deaths annually is based on enthusiastic extrapolation from the mortality seen in much-criticised studies of uranium miners in, for example, North America and Sweden. And, when examining the risk of lung cancer around Britain in relation to domestic radon, you find that the higher the level of radon, the lower the rate of lung cancer Cornwall, with the highest average level of domestic radon in Britain, has about the lowest rate of lung cancer. This is not what you would expect if radon was such a potent lung cancer risk.

There are good reasons for this, of course. Domestic radon comes from the ground dose to and beneath our homes. Although we know that local geology largely determines the domestic level of radon, an important determinant of radon concentration is whether you live in a large detached house (high catchment area so high level of radon), a more modest terraced cottage (lower radon) or in a one-room flat on the top floor of a tower block (tiny radon). In other words, the bigger your home, the more radon you have. But the bigger your home, the richer you are. And the richer you are, the less likely you are to die of lung cancer. You are less likely to smoke, to have a poor diet or live in the polluted inner city.

So the level of domestic radon is a surrogate for wealth. This will (in my view) make it impossible to determine radon risk through epidemiology. There are simply too many other factors which need to be taken into account. By way of contrast, the association between bird-keeping and lung cancer appears strong and robust even when smoking is accounted for. Yet we have no National Ornithological Protection Board nor campaigns to stamp out pigeon-fancying. There is simply nothing in it politically or financially for anybody else.

Wozniak is right to suggest that "billion dollar bandwagons seem not to be fitted with brakes". He has provided a cheap, comprehensive and comprehensible account of the details and complexities of environmental radon. It deserves a wide readership.

Simon Wolff is a lecturer in toxicology at University College London.

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