Re: Article: Lung cancer screening raises lung cancer risk

["Otto G. Raabe" <ograabe@UCDAVIS.EDU>]

At 01:05 PM 6/18/2004, Keith Welch wrote:

>Is this really right?  Are the bomb survivor statistics correct?  How does 

>the cancer risk in the atomic bomb cohort reconcile with the HPS position 

>paper on "radiation risk in perspective" which states that quantitative 

>risk estimates should not be used below 10 rem?  (coincidentally, it seems 

>that position paper is no longer on the HPS website.  Is it under revision?)



*****************************************************************88

The HPS website does have the position statement "RADIATION RISK IN 

PERSPECTIVE", which was last reaffirmed by the SPI committee in March 2001. 

That statement recommends against "quantitative estimation of health risks 

below an individual dose of 5 rem in one year" [50 mSv]. That agrees with 

threshold models of the RERF data that show that a model with a threshold 

of about 5 rem is as plausible as the standard LNT model used by RERF (see 

Hoel and Ping, Health Physics 75:241-250, 1998).



The most recent summary of the RERF data that was presented by Dale Preston 

at the IRPA 11 meeting in Madrid in May did not seem to show a 

statistically significant increase in cancer rates below 50 mSv, although 

RERF continues to believe that their fitted LNT model is correct down to 

the lowest dose group (which serves as the internal control group). RERF 

uses the lowest dose group of survivors as controls rather than using an 

independent control group. The lowest dose group may have reduced cancer 

rates if there are beneficial effects associated with small exposures as 

reported by Mitchel et al. (Radiation Research 159: 320-327, 2003). I have 

not seen any Standard Mortality Ratio values for the atomic bomb survivors, 

so I don't know for sure how they compare to the general population of 

Japanese citizens.



As for Brenner's statement about the atomic bomb survivors in the range 

of  5 to 100 mSv, I would like to know the journal article from which he 

got those data. Among 30,000 survivors one might expect about 6000 cases of 

cancer over the last 59 years since the 1945 atomic bomb exposures. An 

increase to 6077 (77 extra cases) is not a significant increase based on 

Poisson statistics. One standard deviation is the square root of 6,000 

which happens to equal 77. Can anyone explain this?



Otto





**********************************************

Prof. Otto G. Raabe, Ph.D., CHP

Center for Health & the Environment

(Street Address: Bldg. 3792, Old Davis Road)

University of California, Davis, CA 95616

E-Mail: ograabe@ucdavis.edu

Phone: (530) 752-7754   FAX: (530) 758-6140

***********************************************  



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