Domestic radon, smoking and lung cancer
Figures presented in the paper, Darby et al “Radon in homes and risk
of lung cancer: collaborative analysis of individual data from 13 European
case–control studies” BMJ, Jan 2005; 330: 223, show that:
- In the absence of radon, the absolute risks to non-smokers and to
cigarette smokers would be 0.41% and 10.1% respectively by age 75. In
other words, there is a 0.41% risk of lung cancer which has nothing to do
with radon or tobacco smoke, and an additional 9.69% from smoking.
- The incremental risk to non-smokers from radon is about 0.06% per
100 Bq/m3 up to 800 Bq/m3.
- The incremental risk to smokers from radon is about 1.5% per 100
Bq/m3 up to 800 Bq/m3 (about 25 times greater than for non-smokers)
- Hence, at 100 Bq/m3 (which is about the mean value of radon
concentration in this study), the risk to non-smokers from radon is 0.06%
and the total risk to smokers from radon and smoking combined is 11.2%
(about 190 times greater).
I therefore suggest that it is not appropriate to talk simply of a
risk from radon in homes. The risk is from smoking, compounded by a
synergistic effect of radon for smokers. Without smoking, the effect seems
to be so small as to be insignificant.
The findings of Darby et al thus appear to demonstrate that it would
be unreasonable to advise non-smokers that they need to modify their homes
to protect themselves from exposure to domestic radon.
For smokers, the modification of their homes remains an option, of
course, but they should at least be told that a more effective (and
cheaper) way of avoiding the effect of radon is by not smoking.
Competing interests: No competing interests