Not using LNT to calculate risk does not mean there is no risk.

[John Cameron <jrcamero@facstaff.wisc.edu>]

Dear Colleagues, The last HPS NEWS had an editorial by Andy Karam 

discussing the use of LNT to calculate risk at low doses. He points 

out that both HPS and ICRP discourage the use of LNT to calculate 

risk from low doses.  That is not the same as saying there is no 

risk. As far as I know neither HPS nor ICRP have stated there is no 

risk at low doses. If the public believes there is a risk (which they 

do), it makes little difference to them what the calculated risk is. 

They are still afraid of it. The fact that they can't calculate the 

risk might make it seem riskier than quoting a small risk.

	I  sent Andy Karam a copy of my draft letter to HPS News 

commenting on his editorial, requesting his comments. My draft letter 

points out that neither the HPS nor the ICRP have stated that there 

is no risk from low doses.  My letter emphasizes that the evidence is 

very strong that low to moderate doses are beneficial. For example, 

one could use the data from the nuclear shipyard worker study (NSWS) 

to estimate the reduced risk from cancer for a given increase of 

dose. Perhaps more interesting is the estimated increase in longevity 

from an increase in dose based on NSWS. The nuclear shipyard workers 

with the highest cumulative doses (>5 mSv) had nearly three years 

increase in longevity compared to unexposed shipyard workers. 

(Matanoski 1991)

	The 100 year study of British radiologists shows that not 

even the earliest radiologists (1897-1920) had no decrease in 

longevity compared to other male MDs in England, even though they had 

75% greater cancer mortality.  (Berrington et al 2001, Cameron 2002)

	For looking at risks from radiation it seems more reasonable 

to consider the change in longevity rather than cancer incidence. 

British radiologists who entered the field between 1955-1979 had 29% 

less cancer (NS) and 36% lower deaths from non-cancer. Their death 

rate from all causes was 32%, over three years increase in longevity.

	I doubt if you will find anyone on this list server who will 

defend LNT. We must continue to point out the contradictory evidence 

to LNT.

	Best wishes, John Cameron

If you want to know the references ask me by e-mail.



JJ Cohen wrote:

>Unless I've missed something, I do not recall anyone on this list 

>presenting logical reasons in support the continuing application of 

>LNT in our radiation laws, regulation, policies, etc. Even the HPS 

>policy statement attempts to dissuade use of LNT to estimate low 

>dose effects. I have to wonder why LNT based policies (ALARA, 

>Collective dose, etc.) persist. I am sure we are all familiar with 

>assessments indicating massive expenditure of resources pursuant to 

>LNT with little or no resulting public benefit. Can anyone please 

>offer any scientifically based arguments to justify why the 

>public might be better off for our continuing use of LNT?

>

-- 

John R. Cameron (jrcamero@wisc.edu)

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