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Iowa Radon Lung Cancer Study
Radsafers -Good afternoon!
In a message dated 06/08/2000 12:59:59 PM Central Daylight Time,
Holloway3@aol.com posted a general message to the Radsafe Listserv group
indicating he found comments on the Iowa Radon Lung Cancer Study by Mr.
Fumento. Mr. Holloway asked me to comment on Mr. Fumento's articles
concerning the Iowa Radon Lung Cancer Study. I spoke to Mr. Holloway over
the phone concerning Mr. Fumento's articles, but since he posted his question
to the entire listserv ,I feel obligated to respond publicly.
Dr. Holloway,
I would be happy to comment. The comments you refer to were posted by Mr.
Fumento. He has posted his opinion concerning the Iowa Radon Lung Cancer on
his personal web page (http://www.fumento.com/) . Mr. Milloy has also picked
up the editorial and it is posted at Mr. Milloy's site
(http://www.junkscience.com/). It is interesting that there is also a
letter posted at Mr. Milloy's site
(http://www.junkscience.com/news/radon-breast-cancer2.html) concerning a
radon and breast cancer study that I co-authored. I suppose Mr. Milloy and
Fumento think this unfunded study was a good study, because it did not report
an association. I assume that is why Mr. Milloy posted the ecologic study on
his website. The opinions of Mr. Fumento concerning the more recent
case-control epidemiologic study (examining the relationship between radon
exposure and lung cancer) known as the Iowa Radon Lung Cancer Study have also
been published in the Detroit News and National Post. If Radsafers find it
published elsewhere, please let me know.
Specific responses to political comments in the form of an Opinion/Editorial
written by Mr. Fumento, a Fellow from the Hudson Institute, follow. Mr.
Fumento's degrees are in political science and law. The authors of the Iowa
Radon Lung Cancer Study were disappointed by Mr. Fumento's unprofessional ad
hominem attacks against the Iowa Radon Lung Cancer Study Investigators.
Following the ad hominem attacks, Mr. Fumento offered a few criticisms
concerning the methodology and findings of the Iowa Radon Lung Cancer Study.
His article paints an inaccurate picture of the Iowa Radon Lung Cancer Study
findings for the following reasons (Mr. Fumento's criticisms are labeled 1-3,
our responses follow each criticism):
1. Study suffers from recall bias of retrospective mobility?
Recall bias is an improbable contributor to the observed significant
association between radon and lung cancer. Study subjects were indeed asked
to recall their time spent in different locations of their homes. Recall
bias is a problem only if lung cancer cases tend to overestimate their time
spent in locations with higher radon concentrations. However, it is not
reasonable to assume that the subjects know how radon levels vary throughout
their homes. In the absence of this knowledge, case and control subjects
cannot differentially report their time spent in locations with higher radon
concentrations. Consider, for example, the time spent in basements, where
home radon concentrations tend to be highest. There is no significant
difference in the mean times that Iowa cases and controls spent in the
basement. In short, there is no empirical evidence or reasonable argument to
support the claim that the study suffers from recall bias.
2. Arbitrary exclusion of deceased subjects?
Deceased lung cancer cases were not arbitrarily excluded from the analyses.
In fact, one need look no further than Mr. Fumento's own article to
understand the reason for this decision. Mr. Fumento correctly points out
what the investigators knew from the beginning of the study; namely, that
information obtained from relatives is generally less accurate than that
obtained directly from subjects. Deceased subjects were excluded to minimize
the biases and exposure misclassification that might be associated with the
second-hand information from relatives. We included all subjects in one
analysis and "live" subjects in another. The "all" analysis showed a
significant positive trend for categorical analysis, while the "live" subset
analyses were statistically significant for both the continuous and
categorical methods.
3. Statistical significance dependent on radon exposure categorization?
The method used to divide subjects into five exposure categories was decided
upon prior to analyzing any data. Furthermore, the categorical risk analyses
did not produce the only significant study findings. Statistical models were
used to test for a linear association between radon exposure and lung cancer
risk. A significant linear association was reported for the analysis of
continuous radon exposures among live subjects. The continuous exposures are
not affected by the method used to categorize exposure. In other words,
placing 15 percent or 20 percent of the subjects in the highest exposure
category will have no impact on the results from the continuous analyses
The analyses and categorical classification scheme were planned prior to
finalizing the data collection. The Iowa investigators previously published
several peer-reviewed papers to provide additional details addressing the
complex methodology used in the Iowa Radon Lung Cancer Study.
1. Field, R.W., Steck, D.J., Lynch, C.F., Brus, C.P., Neuberger, J.S.,
Kross, B.C., Residential Radon-222 Exposure and Lung Cancer: Exposure
Assessment Methodology. Journal of Exposure Analysis and Environmental
Epidemiology, 6(2): 181-195, 1996.
2. Field, R.W., Smith, B.J., Brus, C.P., Lynch, C.F., Neuberger, J.S. and
Steck, D.J. Retrospective Temporal and Spatial Mobility of Adult Iowa Women,
Risk Analysis: An International Journal, 18(5): 575-584, 1998.
3. Fisher, E.F., Field, R.W., Smith, B.J., Lynch, C.F., Steck, D.J., and
Neuberger, J.S. Spatial Variation of Residential Radon Concentrations: The
Iowa Radon Lung Cancer Study, Health Physics, 75(5): 506-513, 1998.
4. Field, R.W., Lynch, C.F., Steck, D.J. and Fisher, E.F. Dosimetry Quality
Assurance: The Iowa Residential Radon Lung Cancer Study, Radiation Protection
Dosimetry, 78(4): 295-303, 1998.
5. Steck, D.J., Field, R.W., and Lynch, C.F. Exposure to Atmospheric Radon
(222Rn) in Central North America, Environmental Health Perspectives,
107(2):123-127, 1999.
6. Field, R.W. , Lynch, C.F., Steck, D.J., Smith, B.J., Brus, C.P.,
Neuberger, J.S., Woolson, R.F., Fisher, E.F. Platz, C.E., Robinson, R.A.
Iowa Radon Lung Cancer Study, Radiation Research, 151:101-103, 1999.
7. Field, R.W. , Steck, D.J., Smith, B.J., Brus, C.P., Neuberger, J.S.,
Fisher, E.F. Platz, C.E., Robinson, R.A, Woolson, R.F., and Lynch, C.F.
Residential Radon Gas Exposure and Lung Cancer: The Iowa Radon Lung Cancer
Study, American Journal of Epidemiology, 151(11): 1091-1102, 2000.
The method of ascertainment for retrospective mobility histories performed
for the Iowa Radon Lung Cancer Study was peer reviewed by both the journals,
Risk Analysis: An International Journal and American Journal of Epidemiology.
Mr. Fumento's allegations of "trickery" cannot be supported by the written
records of our study. We cannot respond quantitatively to Mr. Fumento about
the outcome of an analysis where 20% of the study subjects were placed in
each category, because we a priori selected uniform exposure categories
rather than quintiles of exposure. We did not engage in multiple analyses
after the fact by varying exposure categories in order to select a particular
result. Rather, we selected an a priori analyses and then we calculated the
results. Those significantly positive results appear in the paper and are
based on sound, defensible scientific procedures. In summary, the three
purported problems with The Iowa Radon Lung Cancer Study's analyses can
hardly be called "tricks," and they certainly do not explain the significant
study findings.
*The specific response to Mr. Fumento's criticisms (above) was written by R.
William Field, M.S., Ph.D., Brian J Smith, M.S., Daniel J. Steck, Ph.D. and
Charles F. Lynch, M.D., Ph.D.
We have received many positive comments concerning the Iowa Radon Lung Cancer
Study Methodology by Scientist. A few quotes follow:
"The Iowa Radon Lung Cancer Study, conducted by Drs. R. William Field,
Charles F. Lynch and colleagues represents by far the most substantial study
of residential radon health effects accomplished to date. By rigorous
analysis of radon exposures for women with lung cancer and matched controls,
this study has shown a clear association between lung cancer and radon
exposures in homes.
A major advantage of this study was the high radon levels found in Iowa
homes, which showed about a 50% increase in lung cancer risk at the EPA
action level of 4 pCi/L. The Iowa lung Cancer Study is a major milestone for
confirming lung cancer incidence due to radon exposures as predicted by the
National Academy of Sciences BEIR VI report. The researchers should be
highly commended for this definitive study showing substantial lung cancer
risks due to radon exposures in homes."
Raymond Johnson, Certified Health Physicist
President, Health Physics Society
---------------------------------------
Dear Bill,
"I wanted to commend you and the other investigators on the Iowa Radon Lung
Cancer Study. I believe the methods you used to reduce the inherent random
error associated with ascertaining long-term residential radon exposure are
critical to validly assessing the lung cancer risk from this source. As you
correctly point out the random error in estimating radon exposure has the
potential to substantially underestimate the slope of the dose-response
curve. Your estimates of risk are similar to my own in our study of lung
cancer among Missouri women, where we used historic estimates of radon
exposure from cumulative measures of radon progeny in glass.
I believe that most studies published to date have been ineffective in
reducing measurement error and their dose-response results have suffered from
a bias toward the null. I look forward to the discussion your results will
generate and urge you to complete the analysis of you radon progeny in glass
measurements data. Along with your current manuscript, that data should help
clarify the true nature of the dose-response curve between residential radon
and lung cancer risk. Again congratulations on a job well done."
Sincerely,
Michael Alavanja, Dr.P.H.
Senior Investigator,
Division of Cancer Epidemiology and Genetics
National Cancer Institute
Rockville, M.D. 20892
---------------------------------------
"The Iowa Study is a significant addition to our already strong understanding
of indoor radon and lung cancer. Its particular importance lies in the
careful methodologic work done by the investigators on some nagging
scientific issues--particularly the estimation of lifetime exposure to radon."
Dr. Jon Samet
Professor and Chairman
Department of Epidemiology
School of Hygiene and Public Health
Johns Hopkins University
Suite 604l
615 N. Wolfe Street
Baltimore, Maryland
In addition, the U.S. EPA recently released this critique of the Iowa Radon
Lung Cancer Study:
-------------------------------------------
U.S. ENVIRONMENTAL PROTECTION AGENCY VIEW OF THE STUDY
The Iowa study is exceptionally well designed and well executed. It adds
to the body of knowledge which designates residential radon as the second
leading cause of lung cancer. It supports EPA's position and the National
Academy of Sciences' Institute of Medicine's 1999 report that radon exposure
in homes is a public health problem. It confirms EPA's, the Center for
Disease Control's, and the Surgeon General's positions that all homes should
be tested for radon, and all homes testing over 4 pCi/L should be fixed. In
terms of scientific advancements, the study breaks new ground in estimating
total individual radon exposure.
---------------------------------------------------------------
We plan to have additional information about the Iowa Radon Lung Cancer Study
posted at the website (http://www.cheec.uiowa.edu/misc/radon.html) in a few
days.
Please email me directly at mailto:bill-field@uiowa.edu if you have any
questions about the Iowa Radon Lung Cancer Study.
Regards, Bill Field
R. William Field, M.S., Ph.D.
College of Public Health
Department of Epidemiology
Department of Occupational and Environmental Health
University of Iowa
Iowa City, Iowa
319-335-4413 (phone)
319-335-4748 (fax)
bill-field@uiowa.edu (email)
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