Threshold

[Ruth Sponsler <jk5554@YAHOO.COM>]

The phrase "_below a certain threshold level_" should

be added to this statement:



"Why would we reduce unecessary radiation

exposure _below a certain threshold level_, unless we

assume LNT?"



Let's assume in a 'future world' on Planet Hardware

(at the Superstore on Planet Hardware, they sell lots

of thresholds for doors) that 0.5-14 R/year is

beneficial, and that 50 R/year is the "NOAEL" [no

observed adverse effect level].  Biological studies

have shown that benefits are less at 50R/y than at

7-14 R/year, but that there is no harm either.  Harm

is seen starting at 100R/y.  Planet Hardware has

instituted a limit of 25 R/year for x and gamma

because they want to maintain a bit of a 'margin of

safety.'



One would always reduce unnecessary exposure if it had

the potential to result in an annual or monthly dose

above the NOAEL.  So, if someone on Planet Hardware

had a monthly reading of 2.08R or more, then they

would have reached their limit for that month, because

2.08R x 12mos. = 25.  



The practical result of changing from LNT to a

threshold model is that monitoring would still be

needed for some things, like industrial radiography,

nuclear plant operations, radiology, but that levels

of interest would be more 'liberal.'



Example: Getting zapped with an almost instantaneous

70R while trying to inspect welds is a serious

_oopsie_, and would be regarded as so, even if LNT

were dropped.  



On the other hand, if LNT were dropped, an

end-of-month reading for a worker repairing pumps or

whatever of 650 mR (external) would be 'so what,' even

if 10R/y were the max, because 0.65R(12mos/y) = 7.8

R/y.



~Ruth 2







--- Gary Isenhower <garyi@BCM.TMC.EDU> wrote:

> 

> Thanks for saying that.  I was wondering how many

> would notice that

> break in rational thought.  Why would we reduce

> unecessary radiation

> exposure, unless we assume LNT?

> 

> Ted Rockwell wrote:

> > 

> > > I think

> > we all agree that if we can reduce unnecessary

> radiation exposure

> > at no cost, then we should do so.  This has

> nothing to do with LNT.

> > It is just common sense.

> > 

> > No, that has nothing to do with common sense. 

> It's just LNT.

> > 

> > Ted Rockwell





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