Re: LNT theories

[Tom Mohaupt <tom.mohaupt@wright.edu>]

Stan,
Why do you say in your example that the pulmonary fibrosis is caused by
radon rather than by the dust particles?

Stan also raises an important issue regarding radon oncogenesis. Do certain
pulmonary diseases give a patient a predisposition for increasing the
incidence of lung cancer? I haven't read any studies where this concept was
investigated. I can easily see where pulmonary fibrosis or emphysema may
inhibit lung cancer because tissue destruction impairs any kind of tissue
(healthy or cancerous) from regenerating; however pneumonia, bronchitis, or
chest colds (perhaps even the forementioned diseases) may be statistically
associated with lung cancer. This concept is not without precedent. The
Oxford Study on Childhood Cancer observed an odds ratio of 2 for children
who suffered pneumonia within two years of developing cancer and 20 for
children with a history of mongolism (Stewart, 1973). Childhood cancer has
also been strongly associated with maternal illnesses (Gilman, 1989). I
would be very surprised if no association existed between pulmonary disease
and lung cancer.

Tom

References:
Gilman, E.A. et al., Childhood cancers and their association with pregnancy
drugs and illnesses, Paediatric and Perinatal Epidemiology, 3, 66-84, 1989

Stewart, A., An Epidemiologist Takes a Look a Radiation Risks, Dept. of
Health, Education, and Welfare (DHEW Publication no. 73-8024), Jan 1973

Stanley Fitch wrote:
> 
> Best regards to Dr. Cohen and Dr. Raabe.  More food for thought
> regarding the argument of LNT vs. negative slope for tissue damage
> relative to low dose.  Although the following comments are relatively
> obvious, I feel they are worth repeating.
> 
> For typical ambient radon concentrations, the mechanisms for cellular
> repair and regeneration are more than adequate.  This in spite of the
> fact that for the general population radon is the leading cause of
> cancer from radiological sources.  As mentioned by Dr. Raabe there are
> aggravating factors, most notably aerosols which can greatly compound
> the effectiveness of radon and its progeny.  Even so, this does not
> detract from the marvelous ability of tissue to repair itself via
> molecular kinetics.  However these kinetics are less successful in the
> scenario of chronic doses somewhat higher than those typical of ambient
> radon.
> 
> A few years ago in the uranium oxide milling industry, our greatest
> concern was to prevent the inhalation and ingestion of dusts to reduce
> the incidence of cancer.  However, medical research of cohorts from the
> industry has revealed a striking incidence of non-cancerous diseases.
> Most notably pulmonary fibrosis.  Under ideal conditions, inhaled
> particles of dust of relatively high activity from radon progeny
> sufficiently irradiate cellular locales to initiate scarring.  A leap
> past cancer directly to scarred tissue masses.  Arguments for either
> hormesis or LNT matter little in this situation where proper repair by
> molecular kinetics is incapable of succeeding.
> 
> Stan Fitch
> stanley_fitch@nmenv.state.nm.us
> 
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-- 
Thomas Mohaupt, M.S., CHP
University Radiation Safety Officer

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