Re: Low-level Rn exposure and lung cancer

["Howard Long" <hflong@pacbell.net>]

Is dose rate range for administration of LDR partly defined by this?

I hope HPs with added certification will soon be administering it.



Could the more easily given (in medical office), quicker LDR actually be

better with radon than longer exposure, as for gamma, favored by Luan from

Taipei experience?



The U or J shaped curve in B Cohen's lung cancer mortality in counties vs

their average home radon levels, explains why in Iowa (highest radon, !%

outlier), cases of lung cancer have higher home radon  than controls (at

>0.4 piCi/l), while on the other, left, side of the U, less than USA av of

c 1.3,  the lung cancer mortality is higher in counties with less radon.



Are biologic defenses stimulated best by a medium dose rate, as well as a

medium total dose (from 1.0 to 4.0 pCi/l) ? See Pollycove's presntations.



Howard Long



----- Original Message ----- 

From: "Steven Dapra" <sjd@swcp.com>

To: <radsafe@list.vanderbilt.edu>

Sent: Wednesday, March 31, 2004 7:34 PM

Subject: Low-level Rn exposure and lung cancer





> March 31

>

> One of the fundamental rules of toxicology (if not <the> fundamental rule)

> is that "the dose makes the poison."  It seems that this is generally true

> of exposure to radiation as well.

>

> While doing some library research on radon and lung cancer I found that

> this rule might not apply for radon exposure and lung cancer.  According

to

> Lubin (1994), " . . . the exposure-response relation declined with

> increasing exposure rate or decreasing exposure duration, implying that

for

> equal total exposure, a higher risk for lung cancer is experienced by

those

> who accumulate exposure at a lower exposure rate and over a longer period

> of time."  (This is quoted from p. 324, col. 2 of an "Invited Commentary"

> wherein Lubin analyzed and discussed approximately 20 papers studying lung

> cancer and radon exposure.  He also drew on other germane research

findings.)

>

> In another paper (Darby et al. 1998) we read (p. 405, col. 1):  " . . .

> greater risks are associated with exposures occurring at a low exposure

> rate and spread over a long duration than for exposures occurring at a

high

> exposure rate with short duration [citations omitted]."

>

> Why does it seem - at least for radon exposure - that lower exposure

> levels lead to a higher risk of cancer?  Does this phenomenon show up for

> exposure to any other type of radiation exposure?  Please note that I do

> not want to instigate a debate about LNT.  I only would like to know why

> this anomaly shows up in the case of radon exposure.  You may reply via

> RADSAFE or via private e-mail, whichever is more convenient.

>

> Steven Dapra

> sjd@swcp.com

>

> REFERENCES

>

> Darby, S. et al.  Risk of lung cancer associated with residential radon

> exposure in south-west England:  a case-control study.  British Journal of

> Cancer.  78(3):394-408; 1998.

>

> Lubin, J. H.  Invited Commentary:  Lung Cancer and Exposure to Residential

> Radon.  American Journal of Epidemiology.  140(4):323-332; 1994.

>

>

>

>

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