Living in an area with a high level of radon gas increases the risk of a lung cancer diagnosis, new research has found.
Exposure to the naturally occurring gas is thought to be the second most important cause of lung cancer worldwide after smoking.
The Economic and Social Research Institute (ESRI) published a new study entitled High Radon Areas and Lung Cancer Prevalence in Ireland, commissioned by the Environmental Protection Agency (EPA).
It links data for more than 5,000 individuals aged over 50 from the Irish Longitudinal Study on Ageing (Tilda) with data on radon exposure risk provided by the EPA.
The researchers found living in an area with a high level of radon exposure increases the risk of lung cancer diagnosis.
This was the case even after accounting for other risk factors that could influence an individual’s likelihood of a lung cancer diagnosis, such as smoking history, age and gender.
Seep into houses
Radon can seep into houses from beneath the ground or from particular building materials.
Ireland has relatively high indoor radon concentrations, estimated to be the eighth highest level among OECD countries.
A radon “risk map” published by the EPA divides Ireland into five zones with increasing levels of risk, from places where less than 1 per cent of houses are expected to have more indoor radon than a set reference level, to others where more than 20 per cent of houses are expected be above this level.
The researchers used statistical methods to see how the odds of a lung cancer diagnosis varied among areas with higher or lower radon risk, controlling for an individual’s smoking history, age, gender, level of education and the population density in their locality.
The researchers found those living in areas where 10-20 per cent of households were above the national reference level for radon exposure (of 200 Bq/m3) were “about three times more likely to report a lung cancer diagnosis than those who live in areas with fewer than 1 per cent of households above the national reference level”.
“However, we do not find increased odds of cancer in the zone where radon risk is highest [more than 20 per cent] of households above the reference level.”
In common with previous research, they found smoking was the greatest risk factor for lung cancer and that risk rose with age.
Radon exposure
The researchers said the results were consistent with the view that radon exposures pose a risk to many Irish households.
A question remained as to why living in the zone with the highest radon risk did not seem to confer higher odds of lung cancer, they added.
“This could indicate that campaigns by public authorities to get households to protect their dwellings in areas with the most radon have had some success.”