radon gas 'a cancer menace' - U of Iowa study

["Franta, Jaroslav" <frantaj@aecl.ca>]

http://news.bbc.co.uk/hi/english/health/newsid_762000/762069.stm
Wednesday, 24 May, 2000, 22:51 GMT 23:51 UK 
Natural gas 'a cancer menace'
A major study of the effect of long-term exposure to radon gas in the home
has produced compelling evidence that it increases the risk of developing
lung cancer. 
A US research team say they have carried out the most sophisticated analysis
of exposure to the naturally-occurring gas ever attempted. 
They concluded that it presents a "significant environmental health risk". 
The findings are in line with 1998 investigation by the Imperial Cancer
Research Fund which found that 1,800 of the 37,000 a year deaths from lung
cancer in the UK are directly linked to radon. 
The four-year US study focused on 1,027 women - 413 had been newly diagnosed
with lung cancer, and the rest were healthy. 
All had lived in their homes for at least 20 years. 
The researchers found levels of radon in the basement of the women's homes
exceeded US Environmental Protection Agency (EPA) guidelines for 60% of the
subjects. 
Radon concentrations exceeding the EPA's action level of 4 picoCuries per
litre were also found in the living areas of 33% of the women with lung
cancer, and 28% of the healthy women. 
Even at the 4 pCi/L level, the researchers found that the risk of lung
cancer was 50% higher. 
'Signficant cause of cancer' 
Lead researcher Professor Charles Lynch, of the University of Iowa, said:
"What this indicates is that residential radon exposure is a significant
cause of lung cancer." 
Most previous studies have focused on only one or two radon measurements in
a home to determine exposure. 
The new study recorded data from at least four radon detection devices
placed in different areas of the home for at least one year. 
Professor Sarah Darby, of the Imperial Cancer Research Fund, said there was
no "incontrovertible evidence" that radon gas posed a cancer risk. 
However, she said the full impact would not be known until a the results of
23 studies world-wide had been fully analysed. The results of this analysis
are due out next year. 
Professor Darby told BBC News Online: "If my house had high levels of radon
gas I would have it reduced, particularly if I had children and I was a
smoker." 
Radon is an odourless, tasteless and colourless radioactive gas produced by
the breakdown of radium in soil, rock and water. 
Equipment is available that can suck away radon gas as it emerges from the
ground, so that it does not contaminate buildings. 
The results are published in the June 1 issue of the American Journal of
Epidemiology.

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