CONTACT: DAVE PEDERSON
2130 Medical Laboratories
Iowa City IA 52242
(319) 335-8032; fax(319) 335-8034
Release: May 25, 2000
UI study: Residential radon exposure poses significant lung cancer risk
IOWA CITY, Iowa -- Long-term exposure to radon in the home is associated
with lung cancer risk and presents a significant environmental health hazard,
according to a study led by researchers at the University of Iowa College
of Public Health.
The Iowa Radon Lung Cancer Study, funded by the National Institute of Environmental
Health Sciences, included investigators from the UI, St. John's University
in Collegeville, Minn. and the University of Kansas. The results are published
in the June 1 issue of the American Journal of Epidemiology.
From 1993 to 1997, the researchers studied 1,027 Iowa women -- 413 who were
newly diagnosed with lung cancer and 614 "controls" -- ages 40 to
84 who had lived in their homes for the past 20 years or more. The women studied
in both groups included smokers as well as nonsmokers. Women were studied
because they typically have less occupational exposures to substances that
may cause lung cancer, and historically have spent more time in the home.
The researchers found that close to 60 percent of the basement radon concentrations
for both the lung cancer cases (study participants with lung cancer) and the
control group (participants without lung cancer) exceeded the U.S. Environmental
Protection Agency action level for radon of
4 picoCuries per liter (pCi/L). The researchers found that 33 percent of living
areas for the lung cancer cases, and 28 percent of the living areas for the
control group, exceeded the EPA's action level of 4 pCi/L.
Even at the EPA action level of 4 pCi/L, an approximate 50 percent excess
lung cancer risk was found among the women in the study after correcting for
the impact of smoking, according to Charles Lynch, UI professor of epidemiology
and the study's principal investigator.
"What this indicates is that residential radon exposure is a significant
cause of lung cancer," Lynch said.
At least four radon detection devices were placed in different areas in
each of the study subjects' homes for one year. The researchers linked these
multiple home radon measurements, as well as estimates on radon exposure outside
the subjects' homes, with the subjects' past mobility history -- where and
how much time they had spent outside or inside their homes or in the workplace,
for example. With this information, the researchers were able to determine
actual detailed exposure estimates for each study participant.
"This study incorporated the most sophisticated radon exposures analysis
ever performed in a residential epidemiologic study," said R. William
Field, Ph.D., UI research scientist in epidemiology and lead author of the
journal article. "Most previous studies have focused on only one or two
radon measurements in a home to determine a person's radon exposure. We linked
where the study participants spent their time over the past 20 years with
the radon concentrations gathered from inside and outside the home and came
up with a more accurate measurement of exposure."
Previous studies have shown that Iowa has the highest average radon concentrations
in the United States. Radon -- a naturally occurring odorless, tasteless and
colorless radioactive gas -- is produced by the breakdown of radium in soil,
rock and water. The high concentrations in Iowa and the upper Midwest are
due primarily to glacial deposits that occurred more than 10,000 years ago,
"Many homes and other buildings, such as schools and offices, have
high radon concentrations," Field said. "Our research provides direct
evidence that residential radon exposure is tied to an increased risk for
The best way to reduce overall exposure to radon is to test homes and take
steps to reduce elevated indoor radon concentrations. Information on radon
testing and mitigation is available toll-free from the National Safety Council
by calling (800) SOS-RADON or by visiting the EPA Web site at http://www.epa.gov/iaq/radon/.
Additional information about the study is available at the following Web site:
The American Journal of Epidemiology is the premier scientific journal devoted
to the publication of empirical research findings and methodologic developments
in the field of epidemiologic research.