July 14, 2006 – A panel of Canadian experts from federal and provincial health departments recommends that Ottawa tighten exposure criteria to radon, a radioactive gas that increases the risk of lung cancer.
The authors of a report1 prepared for the Federal-Provincial-Territorial Radiation Protection Committee estimate that acceptable radioactivity emissions from radon should be reduced by 75%. Currently, the accepted radon standard in Canada is 800 becquerels (Bq – unit of radioactive activity equal to one decay per second of any radioactive body) per cubic meter of air.
According to the committee, these emissions should be reduced below 200 Bq, as in Great Britain, Sweden and Norway. Experts point out that the levels of radon radioactivity considered acceptable in Canada are among the highest in the world, even higher than in some developing countries.
Increased risk of lung cancer
Radon is a colorless, odorless radioactive gas that occurs naturally in the environment. It comes from the natural decay of uranium in soils and rocks. In the open air, the amount of radon gas is very low and poses no health risk.
However, in some confined spaces, such as the basements of homes and buildings, this substance can accumulate, reach relatively high levels and threaten human health.
Alpha particles from the breakdown of radon are then trapped in the lungs and can cause tissue damage in the respiratory system and even lung cancer.2.3. Nationally, experts estimate that lung cancer attributable to radon represents 10% of all lung cancers1.
Results of a recent study reveal that exposure to radon may also increase the risk of leukemia in children4.
In your house?
Radon can enter a home through dirt floors, cracks in concrete walls and floors, sumps, joints, basement drains, the base of boilers and poles if these pass through the floor. This gas easily passes through concrete block walls. If it is present in well water, it can also be released into the air in the house.
Homeowners who wish to have the radon concentrations in their home measured must call on the services of specialized contractors. Currently, very few private companies offer radon testing services to the public.
Decreasing the acceptable level and carrying out a public awareness campaign, as experts recommend, will increase the demand for assessment services. The authors of the report urge Canadian authorities to provide technical advice and support to any entity, public or private, that wishes to provide radon testing services.
They also recommend creating maps illustrating the potential presence of radon in various regions of the country in order to know which areas should be assessed first.
Experts raised the possibility that the state could put in place programs to help owners meet the assessment costs and, if necessary, mitigation measures to be put in place. The technique of active soil depressurization is almost always the most effective mitigation measure when aiming for large reductions in concentrations (80% and more). Installing such a system in a residence costs $ 800 to $ 3,000.
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Risks of lung cancer for a person exposed to radon1 |
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|
|
Smoking |
Non-smoker |
|
Lifetime exposure to radon at 800 Bq / m³ |
30 % |
5% |
|
Lifetime exposure to radon at 200 Bq / m³ |
17% |
2% |
|
No exposure to radon |
12% |
1% |
Pierre Lefrançois – PasseportSanté.net
According to The Globe and Mail and the Canadian Press.
1. Health Canda, Report on the Development of a New Canadian Radon Guideline Prepared by the Radon Working Group, 2006. [Consulté le 28 juin 2006]. www.hc-sc.gc.ca
2. Darby S, Hill D, et al. Residential radon and lung cancer – detailed results of a collaborative analysis of individual data on 7148 persons with lung cancer and 14,208 persons without lung cancer from 13 epidemiologic studies in Europe, Scand J Work Environ Health, 2006; 32 Suppl 1: 1-83.
3. Field RW, Krewski D, et al. An overview of the North American residential radon and lung cancer case-control studies.J Toxicol Environ Health A. 2006 Apr; 69 (7): 599-631.
4. Evrard AS, Hemon D, Billon S, et al. Childhood leukemia incidence and exposure to indoor radon, terrestrial and cosmic gamma radiation, Health Phys, 2006 Jun; 90 (6): 569-79.
