[ RadSafe ] Serious Question: Radon, Radon Progeny, Lung Cancer

[niton at mchsi.com]

Franz,

I agree, but I assume most people use radon as a generic for radon and its 
progeny.  

25 years ago, R. B. McPherson, Health Physics, Vol 39, 929-936, 1980.
wrote -

Radon gas, having a long half-life relative to the time a breath of air remains 
in the lungs (about 17 seconds using a plug flow model) tends to be exhaled 
without depositing a significant amount of radiation energy from daughter 
products to the lung.  To calculate the dose to the lung from inhaled radon by 
itself (radon is a noble gas), a methodology similar to that presented to 
Soldat et al. (So73) is used.  It is assumed that ALL the alpha energy emitted 
from the radon gas in the lung is absorbed in the lung tissue.  A lung volume 
of 4L is assumed to be contaminated to the same radon concetration as outside 
air.
 
Dose Factor = (1pCi/L/m^3)x(10^-3 m^3/L)x(4 L)x(2.22 dis/min-pCi)x(5.49 MeV/dis)
x(60 min/hr)x(8766 hr/yr)x(1.602 x 10^-8 g-rad/MeV)x(1/540g)x(1/8400 m^3/yr) = 
9.1 x 10^-11 rad/pci inhaled.
 
The inclusion of the contribution from the deposited daughter products would 
increase this dose by about a factor of 6% using the assumption that ALL the 
alpha energy emiited from the radon gas was adsorbed in the lung tissue.
 
 
    NCRP (1984) report section 4.3 on radon gas
 
It should be stressed that under usual exposure conditions , the alpha -
emitting short-lived daughters of radon , rather than the radon gas, are the 
recognized principal hazard.  However, it is of interest to derive an upper 
limit on exposure to radon gas alone in the absence of the daughters.  The MPC 
derived from ICRP (1959) under these conditions of 3000 pCi/L to produce a dose 
of 15 rem /year to the lung (Q=10).  Others (Cross et al. 1974) have calcualted 
values close to this (5000 pCi/L) assuming a 3.3 L lung volume and taking into 
account the small additional absorption of radon in the lung tissue.  Selecting 
a functional residual lung capacity of 3.5 L and an average tidal air volume of 
0.5 L, a recalcualted upper limit based upon whole lung dose from exposure to 
radon gas alone is about 4000 pCi/L.  ICRP (1981) derive a limit of 4000 pCi/L 
using Q =20.  Thus values range from about 3000 to 5000 pCi/L.  Radon 
concentrations are of practical importance , although perhaps only where miners 
must resort to respirators for the removal of airborne daughter products.  
 
Regards, Bill
 
 
 




> RADSAFErs,
> 
>  
> 
> My recent posting was not intended as a „funny“. I asked to differ in
> postings on „RADON“ radon and radon progeny apart. Further postings on
> RADSAFE did not at all make any distinction between radon and radon progeny.