Re: linear hypothesis

[Chris Davey <cdavey@med.phys.ualberta.ca>]

<snip>> 
> Unfortunately, as implied in my previous posting, proving or disproving the
> linear no threshold model at low doses is near to impossible. However, the
> linear model is well established at higher doses, and in the absence of
> credible contradictory evidence, I believe that extrapolation of this data
> to low doses is defendable AND scientific. 
> 
100 pain-killers will almost immediately kill anyone who takes them at one 
time.  If we assumed linear response, then 100 people taking one pain-killer 
each would result in one death.  Or 100 million people taking 1 millionth 
of a pain-killer each... same result - one death.

Where in society do we see any examples of linear models, where there is 
no threshold?

It just isn't reality in this neck of the universe.

So I believe that the linear response does not have any decent basis for 
being scientifically acceptable.

 > > The ICRP and NCRP have taken the
> >most conservative hypothesis possible consistent with using radiation
> >and radioactive material at all. There never has been public debate on
> >whether such an idea had, or currently has, merit. 

If we were to use the same conservative approach to all the uses of 
chemicals, etc., in this world, we would have to conclude that nothing is 
safe enough, that no use of anything manufactured by man is acceptable.
We have wasted millions, no, billions of dollars to save milliseconds of 
(postulated) lifetime, and that money could have been used to save years 
of actual lifetime, in progress against disease, etc.

> > > 
Debate on the model should be constrained to appropriately trained
> scientists with access to the best available data, not the general public.
> Perhaps I am naive but I consider the ICRP, NCRP, IRPA etc to fit that
> description.

Analysis must relate to the rest of reality, including all other hazards, 
and involve real use of the ALARA principle, esp. 'social and economic 
factors'.  Have they really done that?
 > > 
> All I want to do is
> >create reasonable debate. We have had the linear hypothesis forced down
> >our throats for more than 50 years. The time has come to question
> >whether the hypothesis is appropriate in this day and age recognizing
> >what has happened to public opinion about the danger of radiation and
> >the consequent gradual, programed demise of the nuclear option.
> 
> 
> What does public opinion have to do with testing a scientific hypothesis? It
> is OUR responsibility to educate the public and to communicate the merits
> and shortcomings of the model. If we allow the results of scientific
> endeavour to be influenced by public opinion we are merely politicians.

Reality!  If the public is sufficiently paranoid about radiation, then 
they'll use their democratic vote to 'do away with it'.
 > 
  <snip>

> Rather, more reasonable regulatory
> requirements (assuming current requirements are unreasonable) based on the
> model and socially acceptable risk should be implemented. Lets face it,
> based on the model, the risks associated with micro Sv doses are negligible
> and regulatory requirements should reflect this. I'm pleased to say that
> here in Queensland Australia, for the most part, they do.
> 
> 
> >Scientists
> >HAVE DICTATED results. They have DICTATED radiation protection standards
> >for more than 50 years. And the standards they dictated have been
> >corrupted in the public mind. Now, either the scientists should fix the
> >corruption or we need different standards. I don't see the scientists
> >fixing anything. All they do is make things more complex without ANY
> >measurable increase in safety. 
> 
> Scientists do not dictate anything. Scientists present hypotheses based on
> data. Advisory bodies make general recommendations based on those models and
> regulatory agencies dictate what thou shalt do based on those recommendations.
> 
People respond to what scientists have been saying.  No one else was 
knowledgeable enough to suggest regulatory limits.  So, in a way, 
scientists have dictated...

> If the standards have been corrupted in the public mind, this is not a
> failing of the model, rather it is a reflection of the general radiophobia
> exhibited by the public due to poor comunication between the scientists and
> the public or the "headlines" philosophy of the popular media. I strongly
> disaggree with the suggestion that new standards should be introduced
> because the public has a tainted view of the existing ones.

People see radiation as unique, because it is the only hazard that 
doesn't (according to the linear hyp) go away at low levels.  Therefore 
the standards HAVE caused the radiophobia.

>   <snip>
> 
>  Maybe the Techa
> >river data will tell us something. Maybe the Chernobyl data, if it is
> >any good, will tell us something. But, until we know radiation at such
> >levels over those time frames is, in fact, harmful, I think it is
> >unethical and immoral to frighten members of the public into thinking a
> >little radiation, no matter how small can and will hurt you.
> 
> 
> We do not seek to frighten the public. We seek to educate the public. If
> anyone is telling the public that a little radiation "can and WILL hurt you"
> that person is acting irresponsibly.

I don't think anyone would suggest that scientists generally would want 
to frighten anyone with conservative (too conservative) guidelines.  The 
point is that people have become frightened, and that this shows that the 
linear hyp is misleading, and does not do the job it was intended to do.

 > >  It is even
> >worse for knowledgable individuals to let that idea remain loose in the
> >world. If scientists, regulators and other knowledgable people would, in
> >a concerted manner, work to eliminate the corruption of the idea that a
> >little radiation MAY cause harm into a little radiation WILL cause harm,
> >I might be more charitable toward the hypothesis. At this point I don't
> >know what else to do except excise the hypothesis.
> 
> 
> How can you base your rejection of any hypothesis on the warped
> understanding of it which the public may or may not have? If your rejection
> was based on studies, data, or even your personal experience, I could
> understand that.  If someone showed me a series of credible studies which
> shot the linear model down in flames, I would drop it faster than a hot rock
.  
The point is that there is no basis for a linear hyp to low levels in any 
other area that I can think of  (if you think of one, just try dividing 
the hazard by a million, then considering if if is still a danger), so 
the onus is not on the one side to DISPROVE the linear hyp. 
but on the other side, to PROVE it!
 > 
> Please don't mistake me for one of the "good old boys" who is forever loyal
> to the linear model no matter what. (I'm much to young for that) I use and
> teach the model, including its shortfalls, because it is the current
> generally accepted hypothesis.

Isn't that a bit of a cop-out?
> 
> PS, its good to see a bit of full on debate on Radsafe!
> 
> Regards
>                        Alex Zapantis
>                        Radiation Safety Officer                               
>                        Queensland University of Technology          
>                        Health & Safety Section                             
>                        Locked Bag No.2
>                        Red Hill Qld 4059
>                        AUSTRALIA
> 
>                        Ph     : 61 7 864 3566
>                        fax     : 61 7 864 3993
>                        email  : a.zapantis@qut.edu.au 

Regards, and hope for a saner future,

Chris Davey	RSO	Cross Cancer Institute
			11560 University Avenue
			Edmonton, Alberta, Canada, T6G 1Z2
			Phone: (403) 492-7477, fax  (403) 492-8202
			email:  cdavey@med.phys.ualberta.ca