RADON may not be as dangerous as has been feared, according to the
authors of a new study of lung cancer victims in Finland. But British experts on
the radioactive gas argue that such a conclusion is premature.
A decay product of uranium, radon can seep up out of rocks and become trapped
inside houses. Over a long period, residents could be exposed to potentially
lethal doses of gamma radiation. Basing their estimates on the high lung cancer
rates among uranium miners, researchers have calculated that up to 10 per cent
of all lung cancers in some countries could be caused by radon.
Although only one out of eight epidemiological surveys conducted worldwide
has found a statistically significant excess of lung cancer victims among people
living in areas with a high exposure to radon, the Finnish scientists have now
openly questioned the existence of a link between indoor radon exposure and the
Anssi Auvinen of the Finnish Centre for Radiation and Nuclear Safety in
Helsinki and his colleagues compared the homes of 1000 people with lung cancer
with those of more than 1000 people without cancer. Radon exposure did not seem
to increase cancer risk. “Indoor radon exposure does not appear to be an
important cause of lung cancer,” the researchers conclude, in the Journal of
the National Cancer Institute.
“There is no question that radon causes lung cancer,” says John Boice, who
recently retired as head of radiation epidemiology at the National Cancer
Institute in the US. “But there is great uncertainty about the effects of low
doses among large populations. This study increases the doubts about the real
risks from low doses in the home.”
Mike O’Riordan of the British government’s National Radiological Protection
Board says current risk estimates hinge on the assumption that there is no
threshold dose of radiation below which the body is safe and that risks among
miners receiving very high doses can be extrapolated to lower doses.
“The Finnish study is technically very good, but very small,” says O’Riordan.
“A few tens of cases would change the results completely. That is not enough for
them to draw the firm conclusions that they claim. Statistically, the results
may not demonstrate a risk from radon, but nor do they demonstrate that the old
estimates are wrong.” O’Riordan is still in the process of conducting a similar
study among residents of southwest England, where radon exposure is particularly