ENVIRONMENTAL HEALTH SCIENCES RESEARCH CENTER
A National Institute of Environmental Health Sciences Center of Excellence

Exposure to Residential Radon and Lung Cancer

Contacts:

To Order a Radon Test Kit:

Iowa AIR Coalition
501 13th Street NW
Cedar Rapids, Iowa 52405-3700
(319) 892-6000 or
(800) 206-7818

IA Department of Public Health

Richard L. Welke
Program Manager
Radon/IAQ Program
Bureau of Toxicology and Environmental Health
Iowa Department of Public Health
321 E. 12th Street
Des Moines, IA  50319-0075
TEL:  1-800-383-5992
rwelke@idph.state.ia.us

http://www.idph.state.ia.us/eh/radon.asp

Radon gas is an important environmental lung carcinogen with extensive exposure occurring in the rural Midwest.  A review conducted by The National Research Council on risks of radon exposure concluded that it was the second leading risk factor for lung cancer and may be responsible for up to 20,000 excess lung cancer deaths per year in the United States.  Three independent radon surveillance surveys have established that radon is an important residential exposure in Iowa.  A U.S. EPA survey of 25 states conducted during the winter of 1989 found that 71% of Iowa's homes exceeded the recommended health advisory level of 4 pCi/L making Iowa the state with the highest radon levels among all states tested.  The second survey, that included 2,100 short-term, first-time radon screening test levels, found 70% of Iowa residences to have radon levels greater than the 4 pCi/L level.  A third survey conducted by EHSRC investigator Burton Kross, tested 590 homes in rural Iowa and also found that 70% of the rural homes exceeded the 4 pCi/L radon advisory level, that the mean concentration was 10.1 pCi/L and that 11% of these homes exceeded 20 pCi/L.  The most recent EHSRC study of radon concentrations in Iowa and Minnesota found unusually high annual average radon concentrations.

Between 1990 and 1994, seven large-scale case-control studies of indoor radon and lung cancer reported mixed results of the effects of radon inhalation.  As a result, a debate ensued as to whether residential radon exposure posed a serious risk for lung cancer.  The lack of definitive results from these studies may have been due to several limitations including: 1) low mean radon levels and limited ranges of exposure, 2) misclassification of exposure from the use of contemporary radon measurements to estimate exposures in years past, 3) high mobility of subjects, 4) alterations in houses, and 5) measurements in only one or two areas of the home, ignoring other sources of exposure inside and outside the home. 

EHSRC investigators conducted a study of residential radon in Iowa which addressed each of these limitations.  The Iowa Radon Lung Cancer Study reported excess risk related to odds ratios two to six times higher than the combined summary excess odds from a recently published meta-analysis of eight previous studies.  The study obtained radon measurements from all levels of a home, in contrast to previous studies that obtained their measurements from basement or bedroom and living room areas.  More complete exposure assessment was shown to yield higher odds ratios and higher excess risks. 

In addition, EHSRC investigators measured radon (222Rn) concentrations in Iowa and Minnesota and found that unusually high annual average radon concentrations occur outdoors in portions of central North America.  In some areas, particularly western Iowa, outdoor concentrations exceed the national average indoor radon concentration.

Implications and Public Health Impact

These EHSRC investigators concluded that more thorough radon exposure assessments contribute to higher risk estimates for radon-associated lung cancer. Investigators have recently developed new retrospective radon detectors. Initial work compared the track rate densities produced by two different glass-based retrospective detectors used in the Iowa Radon Lung Cancer Study and the Missouri Radon Lung Cancer Study. Further work examined the contemporary monitoring capabilities of the glass-based retrospective radon detector to assess the contemporary radon equilibrium in the Iowa Radon Lung Cancer Study Homes.  These contributions from EHSRC investigators have clearly extended our understanding of the relationship between radon exposure and cancer risk.

Center Contribution

The EHSRC Pulmonary Biology Research Core brought these investigators together on this line of investigation.  Drs. Kross and Lynch were introduced through the EHSRC and Dr. Field was trained as a doctoral student within the EHSRC.  The Environmental Measurements Facility (later renamed the Exposure Assessment Facility) provided the equipment for several of the studies described in this highlight. Together, Drs. Kross and Field received an EHSRC pilot grant in 1991 for studies of radon.

Key Researchers and NIEHS Support

R. William Field, Research Scientist, Department of Epidemiology, P30ES005605, 1R01CA085942;
Charles F. Lynch, Professor, Preventive Medicine and Environmental Health, The University of Iowa, 5P30ES005605, 1R01ES005653

References

Field RW, Becker K. Does exposure to residential radon increase the risk of lung cancer? Radiation Protection Dosimetry, 95 (1): 75-78, 2001.

Field RW, Kross BC, Vust LJ.  Radon testing behavior in a sample of individuals with high home radon screening measurements.  Risk Anal. 1993 Aug;13(4):441-7.

Field RW, Kross BC, Weih LM, Vust LJ, Nicholson HF.  Factors associated with elevated 222Rn levels in Iowa.  Health Phys. 1993 Aug;65(2):178-84.

Field RW, Kross BC.  Field comparison of several commercially available radon detectors.
Am J Public Health. 1990 Aug;80(8):926-30.

Field RW, Kross BC. Iowa survey of waterborne 222Rn concentrations in private wells.  Health Phys. 1998 Feb;74(2):249-52.

Field RW, Kross BC. Iowa survey of waterborne Rn-222 concentrations in private wells.  Health Physics, 74 (2): 249-252, 1998.

Field RW, Lynch CF, Steck DJ, Fisher EL.  Dosimetry quality assurance:  Iowa residential radon lung cancer study. Radiation Protection Dosimetry, 78 (4): 295-303, 1998.

Field RW, Lynch CF, Steck DJ, Smith BJ, Brus CP, Neuberger JS, Woolson RF, Fisher EF, Platz CE, Robinson RA: Iowa radon lunch cancer study. Radiation Research 151:101-103, 1999.

Field RW, Lynch CF, Steck DJ. Re: Residential radon gas exposure and lung cancer:  The Iowa Radon Lung Cancer Study – The authors reply. American Journal of Epidemiology, 152 (9): 895-896, 2000.

Field RW, Smith BJ, Brus CP, Lynch CF, Neuberger JS, Steck DJ:  Retrospective temporal and spatial mobility of adult Iowa women.  Risk Analysis 18(5):575-584, 1998.

Field RW, Smith BJ, Lynch CF. Comment On the discrepancies between epidemiologic studies of lung cancer and residential radon and Cohen’s ecologic regression – Response. Health Physics, 76 (3): 318-319, 1999.

Field RW, Smith BJ, Lynch CF:  Cohen’s paradox.  Health Physics 77(3):328-329, 1999.

Field RW, Smith BJ, Lynch CF:  Ecologic bias revisited, a rejoinder to Cohen’s response to residential 222Rn exposure and lung cancer:  testing the linear no-threshold theory with ecologic data.  Health Physics 75(1):31-33, 1998.

Field RW, Smith BJ, Steck DJ, Lynch CF. Residential radon exposure and lung cancer:  Variation in risk estimates using alternative exposure scenarios. J Exposure Analysis and Environmental Epidemiology, 12 (3): 197-203, 2002.

Field RW, Steck DJ, Lynch CF, Brus CP, Neuberger JS, Kross BC:  Residential radon-222 exposure and lung cancer: radon-22 exposure assessment methodology.  Journal of Exposure Analysis and Environmental Epidemiology 6:181-195, 1996.

Field RW, Steck DJ, Parkhurst MA, Mahaffey JA, Alavanja MCR. Intercomparison of retrospective radon detectors. Environmental Health Perspectives, 107 (11): 905-910, 1999.

Field RW, Steck DJ, Smith BJ, Brus CP, Fisher EF, Neuberger JS, Lynch CF. The Iowa radon lung cancer study – phase I:  Residential radon gas exposure and lung cancer. Science of the Total Environment, 272 (1-3): 67-72, 2001.

Field RW, Steck DJ, Smith BJ, Brus CP, Fisher EL, Neuberger JS, Platz CE, Robinson RA, Woolson RF, Lynch CF. Residential radon gas exposure and lung cancer – The Iowa radon lung cancer study. American Journal of Epidemiology, 151 (11): 1091-1102, 2000.

Field RW. Iowa Radon Lung Cancer Study. Radiation Research, 151 (1): 101-103, 1999.

Fisher EL, Field RW, Smith BJ, Lynch CF, Steck DJ, Neuberger JS:  Spatial variation of residential radon concentrations:  the Iowa radon lung cancer study.  Health Physics 75(5):506-513, 1998.

Fisher EL, Fuortes LJ, Ledolter J, Steck DJ, Field RW. Temporal and spatial variation of waterborne point-of-use Rn-222 in three water distribution systems. Health Physics, 74 (2): 242-248, 1998.

Neuberger JS, Lynch CF, Kross BC, Field RW, Woolson RF.  Residential radon exposure and lung cancer: evidence of an urban factor in Iowa.  Health Physics 66(3):263-269, 1994.

Smith BJ, Field RW, Lynch CF:  Residential 222Rn and lung cancer:  testing the linear no-threshold theory with ecologic data. Health Physics 75(1):11-17, 1998.

Steck DJ, Field RW, Lynch CF:  Exposure to atmospheric radon (222Rn).  Environmental Health Perspectives 107:123-127, 1999.

  Environmental Health Sciences Research Center, The University of Iowa, University Research Park, #178 IREH, Iowa City, IA 52242

Tel: (319) 335-4756 / Fax: (319) 335-4225 / E-mail: nancy-wyland@uiowa.edu