Re: Linear Hypothesis IS the Cause of P

["John Moulder" <jmoulder@post.its.mcw.edu>]

> John Moulder wrote: 
> > This is not to imply that the applicability of LNT in the above 
> > is justified, only to point out that this thinking is not limited to 
> > ionizing radiation. 
>  
> You are absolutely correct currently.  However, the LNTH was thought up 
> by the ICRP and NCRP long before the Delaney amendment.  I wonder if 
> those who drafted the Delaney amendment knew about the LNTH for 
> radiation.  It would be interesting to know if they did and then used 
> the same philosophy.

For those not in the US, the Delaney Clause was contained was in the Federal 
Food Drug and Cosmetic Act of 1958. The Delaney Clause states that no additive 
will "be deemed safe if it is found to induce cancer when ingested by man or 
animal," and directs FDA not to approve such food additives. Its language has 
been interpreted to mean a "zero risk" standard for any cancer-causing food 
additive, including residues from pesticides found in processed foods.

While the Delaney clause, as it was implemented, appears to assume no 
threshold, it is not at all clear that the LNTH was part of the thinking in 
the 1950s.  I would argue that the Delaney Clause is an example of "no risk, 
however small, is acceptable" thinking, rather than an example of use of the 
LNTH.  In the contemporary stories about Delaney, I'm not aware of any 
explicit mention of ionizing radiation. 

In any case, the thinking behind Delaney dates from the early 1950's.  I 
believe that the first formal use of the LNTH hypothesis in radiation safety 
is in UNSCEAR 1958, although NCRP 1954 comes close to an LNTH argument.  In 
summary then, Delaney and the use of LNTH in radiation safety seem to be the 
result of parallel thinking.  I would argue that this supports the idea that 
LNTH derives from "no risk, however small, is acceptable" thinking, rather 
than the other way around.

BTW:  My collegue Bill Hendee has written a history of the orgin of LNTH in 
radiation safety, but I don't think it is yet published.  I will check.


John Moulder (jmoulder@its.mcw.edu)
Radiation Biology Group
Medical College of Wisconsin