assessment of risk from doses recieved during a radiological accident

[JGinniver@AOL.COM]

Before I begin, I would like to point out that I'm aware of the concerns 

often cited on radsafe about the use of collective dose and the use of collective 

doses to provide a value for future risk.  However when attempting to justify 

the adoption or otherwise of measures to mitigate risk the UK regulators only 

seem to accept arguments based on risk of death (and if using ICRP recommended 

values of loss of quality of life).  This results in justifications which go 

something like, if no action is taken the collective dose will be something of 

the order A person Sv, and this will result in B deaths, alternatively if 

some action is taken to mitigate the effects of the accident (classed as 

intervention by the ICRP) then it will only result in a dose of X person Sv, and hence 

 Y deaths.  A comparison can then be made about whether the benefit of 

intervention outweighs the detriment from that intervention possible cost if it is 

put in place before and accident or dose if individuals have to physically 

intervene.



What I am interested in, is whether there are other ways of establishing 

whether some form of intervention is justified, particularly where acute exposure 

are considered.  The reason for this is that in circumstances of acute 

exposure it is clear that the absorbed dose is the appropriate unit to use.  However 

factors used to derive the absorbed dose in tissue from high LET radiation are 

not designed to be used for estimates of risk (those stochastic effects that 

may or may not occur).  There is guidance for quality factors (in ICRP 58) for 

the RBE of high LET radiations for deterministic effects following acute 

exposures.  However it is explicitly stated that these factors only apply to 

deterministic effects, and not stochastic effects.



It would appear, to me at least, that in order to satisfy the regulator, we 

can only calculate the collective dose in Sv and translate this into an overall 

risk from the exposure.  This doesn't seem to be a sensible or even 

justifiable approach.  



I would be grateful if anyone could provide thoughts on alternatives.  Links 

to publications/literature would be most helpful.



Regards,

       Julian