Re: Radon Health Hazard, Myth or Reality?

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

Dr. Scribner:
     We start any appraisal with two widely accepted facts.
       I. Radon exposures are a large fraction of background radiation
from natural sources, and the exposures may vary with local geology,
housing, and possibly local meteorology.
       II.  Radon exposures occur occupationally to miners, and there
have been several convincing epidemiological studies relating dose to
probability of lung cancer.
     It follows that your question needs refinement concerning what kind
of health hazard and to whom.  I assume that you refer to the general
public, rather than to occupationally exposed miners and to risk of lung
cancer.
     The premise of community health hazard is partly based on
quantitative extrapolation of miner's occupational exposure to those
of the general population.  Recently some doubt as to the suitability of
direct extrapolation has arisen because of the demonstration of the
carcinogenic risk of silica exposure, a frequent co-exposure for miners.
In other words some of the excess cancer risks in underground miners is
associated with silica exposures and some to radon, and some to a
combination. (Assuming we are speaking of populations with equivalent
smoking exposure, since smoking is by far the most potent cause of lung
cancer.)     
      A number of general population studies of risk from
contemporary measurements of radon have been done, and meta-analyses 
are consistent with a small association with lung cancer.  The one
anomalous report is that of Dr. Bernard Cohen of the University of 
Pittsburgh, who by lumping together data from different types of studies,
finds a significant negative relationship of radon and lung cancer by 
County in the U.S.  Part of the problem is that the analysis depends on
the lung cancer data for the totality of the county residents and the
measurements are from a (usually) self-selected subset of households.
The self-selection favors the more suburban dwelling units, while lung
cancer is strongly associated with population desnity.
     Professor Cohen has made some of his data available, and I have
recently examined a subset obtained by EPA.  Briefly, the data for
counties in eight states with high radon levels in the EPA subset, show no
significant associations between log radon and lung cancer for males or 
for females.  (Lung cancer rates are age adjusted.)
     Health risks to the general population from background levels of 
radon are no myth, but except for the rare,unusually high residential 
exposures, the risks are small and difficult to detect.  
               John Goldsmith, M.D, M.P.H.  Professor of Epidemiology,
                gjohn@bgumail.bgu.ac.il  Ben Gurion University,
                  Beer Sheva Israel