New studies have found direct evidence of a lung cancer risk from the presence of colorless, odorless radon gas in many homes, a United Nations committee said in a report released Tuesday. Officials on the U.N. Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) said the finding provided the first quantifiable evidence of the risk in homes from radon, long seen as a potential health risk.

The World Health Organization (WHO) and other agencies were revising recommendations on maximum levels of radon in homes and workplaces based on the 20 studies involving tens of thousands of lung cancer patients in North America, Europe and China.

(Up to now) radon has been a typical health risk no one wants to accept or take note of, Wolfgang Weiss, UNSCEAR's vice chairman, told a news conference.

He said the report was significant because previous estimates of radon risks to the public were extrapolated from studies of uranium miners exposed to high levels of the gas.

In the meantime we've done 20 studies in homes where concentrations are very low, and there we can see a risk, it is small, but it is certainly there, said Weiss.

You can avoid smoking by just taking personal decisions, he said, referring to the leading cause of lung cancer.

(But) radon is everywhere. So (you need to) develop strategies to avoid the influx of radon into houses ... It's very simple to seal basements, for example with plastic foil.

Radon is a hard-to-detect radioactive, noble gas that comes from natural decay of uranium. It can accumulate in buildings, seeping in from the ground through cracks in cellars, and may also be emitted by spring waters and hot springs.

Weiss said UNSCEAR's findings had caused a rethink at the WHO and other health policy agencies. There will be consequences in regulation through the lowering of recommended levels of radon in workplaces and homes.

Some developed countries like Switzerland and Germany have conducted surveys or drawn up maps identifying radon-prone and low-radon regions, but many others provide no such information.

The report said radon concentrations in indoor air were lowest in the Middle East and highest in some European nations, where uranium is highly present underground.

UNSCEAR was set up in 1955 and reports to the U.N. General Assembly. Its research helped bring about the 1963 treaty that banned atmospheric testing of nuclear weapons, and underpins global standards on radiation protection.

China Cancer