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RE: TRAB and back to Re: Lung cancer mortality from radon versus ....



Michael,



Dr. Field's reply sounds like the same thing I had stated previously.



Try putting 15% of the subjects in the upper exposure group and then you 

break the remainder up evenly, what WLM categories do you get?



They found statistical significance when all subjects were included and when 

the subset analysis only included lung cancer patients that were alive at 

time of interview.  No one who died was excluded.



I congratulate Dr. Field and the other investigators on the study for their 

landmark study and excellent detailed retrospective assessment of radon 

exposure.  I see Dr. Field worked as a health physicist and a co-author was 

Dr. Steck a nuclear physicist (and both members of the HPS since the early 

1980s), unlike the miner studies it looks like they incorporated much of 

their past health physics experience into that study including publishing an 

entire paper just on QA for the study.



I would also urge Dr. Cohen to follow the well thought out suggestions by 

Dr. Field for improving his ecologic analyses.



Respectfully, Don Smith



_________________________________________________________________

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I logged back onto Radsafe merely to offer a suggestion to Dr. Cohen concerning how he could improve his ecologic analyses.  But then, Michael Ford asked in his last post on this subject if I would like to step in on this different debate.

Posting on these subjects is like getting drug in quick sand surrounded by alligators.  But, because I have been asked to comment I will.  Not commenting gives the impression the characterizations from Mr. Ford are correct.

As I told Michael before, after their letter to then Gov. Bush was published in the Billett, I received a half dozen emails from that local Health Physics Chapter asking me to respond to what they perceived as the misrepresentations of the Iowa Radon Lung Cancer Study in the letter.  I was sent a copy of the Billet and agreed that the Texas Radiation Boards (TRAB) letter (which was published in the Billet) did not present the facts clearly.  I contacted members of the TRAB and was told Mr. Ford drafted the letter, but it was approved by the whole TRAB.  I later found out that many of the erroneous statements in the letter were influenced by postings on Radsafe about the Iowa Study.  I spoke to Mr. Ford and indicated I did not think that Radsafe was a scientific forum and a good place to determine the validity of a study.  It was obvious the TRAB was not going to issue a correction to their letter so I was left with writing a letter-to-the-editor of the Billet, which was graciously published.  To this date, I have not heard any official response from the TRAB concerning the letter.  I have attached the letter below (I think it was the last draft), which I sent to the Billet.

I would be happy to discuss any of the issues by direct email.  Posting on Radsafe appear to have a life on their own somewhat like the numerous lives of a cat.

Iowa Radon Lung Cancer Study


Dear Editor,

The October 12, 2000 edition of the Billet contained a copy of a July 28, 2000 letter written to the Honorable George W. Bush and signed by Dr. Dale E. Klein on behalf of the Texas Radiation Advisory Board (TRAB).   In the letter, the TRAB recommended that the State of Texas challenge the EPA’s proposed rules in the Safe Drinking Water Act regarding waterborne radon.  As part of the justification for their position, the TRAB made misleading allegations about the Iowa Radon Lung Cancer Study.  The Iowa Radon Lung Cancer Study (1) was a large-scale case-control epidemiology study that found a statistically significant association between prolonged residential radon exposure and lung cancer. The study was performed in Iowa and the participants were women throughout Iowa who lived in their current home for at least 20 years. The study was funded by the National Institute of Environmental Health Sciences.

The TRAB letter contains three erroneous allegations. The first false allegation was that the Iowa Radon Lung Cancer Study was only able to establish statistical significance by omitting cases that died during the study period.  In fact, the study did NOT omit cases that died during the study period. Analyses were performed on all cases as well as on the subset of cases that were alive at time of interview. In addition, contrary to the statement above, the trend in risk (odds ratio) with increasing cumulative radon exposure was statistically significant for the categorical analyses for all the subjects.  The trend analyses for the subset were also statistically significant.

        The second false allegation was that the study was only able to establish statistical significance by carving up the data into non uniform intervals. In fact, the method used to divide subjects into five exposure categories was decided upon prior to analyzing any data. This included the decision to place 15% of the subjects in the highest exposure category so that there would be an adequate sample size for analysis. The cumulative radon Working Level Month (WLM) exposure categories were evenly spaced intervals.
 
        The third false allegation was that the study was only able to establish statistical significance by poorly correcting for disparities in smoking histories between cases and controls. In fact, the study controlled for smoking at the level of the individual. Detailed individual smoking histories were obtained for all cases and controls. The cases’ smoking histories do not need to match the smoking histories of the controls since the effect of smoking can be adjusted for using standard statistical methods. Moreover, misclassification of smoking status would bias a study’s findings toward no association in the majority of cases. In order to get a radon dose response relationship attributable to poor recall of smoking, the misclassification of smoking would have to correlate with radon exposure. In other words, individuals would have to independently know their radon concentrations in their home and increasingly under report their smoking habits as the residential radon concentrations increase. Since most people in a study were unaware of the radon concentrations in their home at time of interview, that is a very unlikely scenario. Other papers supporting the methodologies used in the Iowa Study are listed below (2-8). 


R. William Field, Ph.D.
College of Public Health
N222 Oakdale Hall
University of Iowa
Iowa City, Iowa 52245
mailto: bill-field@uiowa.edu



1.      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.

2.      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.

3.      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.

4.      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.

5.      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.

6.      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.

7.      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.

8.      Field, R.W. , Steck,  D.J., Smith, B.J., Brus, C.P., Neuberger, J.S., Fisher, E.F., and Lynch, C.F. The Iowa Radon Lung Cancer Study Phase I: Residential Radon Gas Exposure and Lung Cancer, The Science of the Total Environment, 272: 367-72, 2001.





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