Re: Housing versus Radon Issues Again

[John Goldsmith <gjohn@bgumail.bgu.ac.il>]

Dear Steve:
     You are right.  The original estimaates of miner's radon and lung 
cancer associations  of which Ted Radford was a leading investgaor did 
not take into account the additional cancer risks of silica exposures.
The reasons are simple; the carcinogenicity of silica had no yet been 
generally recognized. 
	This is not to say that radon may not be carcinognic, but that 
all of the carcinogeniciy among uranium miners may not be due to radon.
      Murray Finkelstein writing in Health Physics ,vol 69:396-399
in 1995 "Silicosis, Radon, and Lung Cancer Risk in Ontario Miners"
provides a reanalysis for the joint effect of silica and radon in a sample
of Ontario miners with silicosis.  While in a matched case-control study
cumulative radon exposure was associated with lung cancr risk ( increase 
in odds ratio of 0.4% per WLM,) When silicosis was added to the model, 
silicolsis was a highly significant factor for lung cancer (Odds Ratio 
6.99, with 95% Confidence interval of 1.91-25, and the risk factor for 
Radon was diminished (incrase in Odds Ratio -0.5% per WLM; 95% confidence 
limits -1.4% to 0.4%)  He writes " This finding suggests that additional 
study is warranted before concluding that radon risk factors derivd from 
mining populations do not need to be modified for application to the general 
population".  Samet et al. in a case-control study of New Mexico Uranium 
miners found no association between radiographic silicosis and lung 
cancer and concluded that silica exposure should not be regarded as a 
major uncertainty in extrapolating radon risks from miners to the 
genertal population."  (Samet et al. Health Physics 66:450-453, 1994)
 Silica could be less of an exposure problem in New Mexico than in 
Ontario.There are, of course arguments as to what model we 
should use for evaluating the joint effects of silica, radon and smoking.
We don't yet have the answer, but I doubt that the simple extrapolation 
of miner's lung cancer-radon association to the general population will 
continue to be widely accepted.
    John R. Goldsmith, M.D., M.P.H.  gjohn@BGUMAIL.BGU.AC.IL
On 
Wed, 26 Feb 1997 steve.meith@internet.nps.usace.army.mil wrote:

>      Dear subscribers:
>      
>      My understanding on the issue(s) is that the studies did not take into 
>      account exposure to silica, radioactive and non-radioactive 
>      respirable/inhalable dusts or other possible airborne chemicals       
>      generated by the mining activities.  
>      
>      I am hoping that at least one of you know if my impression is correct 
>      or would be so kind as to provide me with the name and address or 
>      someone who might be able to clarify this issue for me.  
>      
>      I am aware that quartz and cristobalite (common forms of crystalline 
>      silica) have recently been classified as known human carcinogens, and 
>      that crystalline silica is quite apt to be found in areas where 
>      uranium ore is located.  I also do not know exactly which methods were 
>      used for mining uranium at the time.  Is it possible that internal 
>      combustion diesel fueled equipment was used in the mines? 
>      
>      Please note that I am NOT trying to inflame anyone, or myself for that 
>      matter, I am merely seeking further understanding on the Rn vs housing 
>      issue and would greatly appreciate any enlightenment which you or your 
>      cohorts might provide.
>                 
>                                 Sincerely,
>                                 Stephen Meith
>      
>      
>      US Army Corps of Engineers
>      PO Box 3755
>      Seattle, WA 98124-3755
>      [V] (206) 764-3415/[F] (206) 764-6795
>      <stephen.j.meith@nps.usace.army.mil>
>      
>      
>