Re: Alpha radiation as tests of LNT

[Dick King <king@reasoning.com>]

>> 
>> Date: Wed, 31 Jul 1996 13:55:12 -0400 (EDT)
>> From: Bernard L Cohen <blc+@pitt.edu>
>> Subject: Re: Alpha radiation as tests of LNT
>> 
>> 	The risk from radon is determined from data on miners who 
>> contracted lung cancer from high exposures in mines. LNT simply says that 
>> the risk of lower exposures is linearly related to the dose.Nothing else 
>> is involved.Presumably, if a single alpha particle can kill a cell, the 
>> number of cells killed is also linearly related to dose.

This doesn't follow at all.

It may be that a single alpha particle can kill a cell with a very low
probability because there is one tiny target that can be killed with a single
hit, but that there is a much bigger nonlinear target, such as the DNA, that
needs to take more than one hit before the repair can take place.


With low doses the main kill mechanism is the single hit mechanism, but damage
is very light.  High doses are nonlinear.



Note carefully that even if the number of cells killed is linear in the dose
that doesn't mean that health effects are proportional to dose.  If you kill
50kg of cells in one person the person dies.  If you kill 50mg of cells taken
at random in each of a million people probably almost nobody would notice.
Each person would lose one or two pixels of vision, perhaps, and a pixel of
skin sensation somewhere, etc. but cells die all the time.


-dk