Sept. 21, 2009
UI professor contributes to WHO's first comprehensive global initiative on radon
University of Iowa professor R. William Field, Ph.D., is part of an international team of scientists who contributed to a new World Health Organization (WHO) publication that calls on countries to either strengthen or establish programs to control the presence of radon in homes and other residential settings.
Field is presenting the keynote address launching the new WHO handbook at this year's International Radon Symposium Sept. 21, in St. Louis, Mo.
Radon is a radioactive gas that emanates from rocks and soils and tends to concentrate in enclosed spaces like underground mines or houses. The new "WHO Handbook on Indoor Radon: A Public Health Perspective" indicates that radon exposure is a major and growing public health threat in homes and recommends that countries adopt reference levels of the gas of 100 Bq/m3 (Becquerel per cubic meter).
If this level cannot be implemented under the prevailing country-specific conditions, WHO recommends that the reference level should not exceed 300 Bq/m3. The current U.S. Environmental Protection Agency action level is set at 148 Bq/m3.
"Radon is the second leading cause of lung cancer in the general population, after smoking. It is also the leading environmental cause of cancer mortality overall," said Field, professor of occupational and environmental health and epidemiology in the UI College of Public Health. Field served as an editor for the handbook, chaired the project's working group on radon measurements and was a member of several of the publication's other working groups.
Most radon-induced lung cancers occur from low- and medium-dose exposures in people's homes. The handbook notes that strengthened action by policymakers as well as construction and building professionals can substantially lower the health impact by preventing and reducing radon exposure.
The concentration of radon in a home depends on the amount of radon-producing uranium in the underlying rocks and soils, the routes available for its passage into the home and the rate of exchange between indoor and outdoor air. Radon gas enters houses through openings such as cracks at concrete floor-wall junctions, gaps in the floor, small pores in hollow-block walls and through sumps and drains. Consequently, radon levels are usually higher in basements, cellars or other structural areas in contact with soil.
While the lung cancer risks of high-dose radon, typically found among uranium miners, for example, have been known for many years, new studies in Europe, North America and China -- summarized in the new WHO handbook -- have confirmed that low- and medium-level exposures to radon in homes contribute substantially to the occurrence of lung cancers worldwide. Recent estimates of the country-specific proportion of such lung cancers attributable to radon range from 3 percent to 14 percent.
Lung cancer risk rises 16 percent per 100 Bq/m3 increase in radon exposure. Studies show that radon is the primary cause of lung cancer among people who have never smoked. However, the absolute numbers of radon-induced lung cancers are much larger in people who smoke, or who have smoked in the past, due to a strong combined effect of smoking and radon.
"Key actions needed to achieve radon concentrations at or below the recommended reference level include establishing and strengthening radon measurement and mitigation programs and developing building codes that require radon prevention measures in homes under construction," said Maria Neira, director of WHO's Public Health and Environment Department. "Countries are encouraged to use the handbook to initiate national radon programs or to promote their existing programs."
The International Radon Project (WHO-IRP), producers of the WHO handbook on indoor radon, has involved over 100 experts from more than 30 countries. The handbook is the first comprehensive international compilation of information and recommendations on radon and its public health effects. It includes the latest evidence on health risks, measurements, mitigation and prevention techniques and their cost effectiveness, as well as information on radon risk communication. Additionally, specific recommendations are presented for national radon programs.
For more information:
WHO Handbook on Indoor Radon: A Public Health Perspective:
U.S. Environmental Protection Agency radon information
NOTE TO EDITORS: This release includes information prepared by the World Health Organization.
STORY SOURCE: The University of Iowa College of Public Health Office of Communications and External Relations, 4257 Westlawn, Iowa City, Iowa 52242
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