Re: EPA, risk and dose

[BLHamrick@AOL.COM]

In a message dated 03/29/2001 6:13:52 AM Pacific Standard Time,

StokesJ@ttnus.com writes:







> Over the decades, BEIR has altered the risk associated with a

> given level of dose.  Therefore the risk associated with a given dose is 

not

> a constant.  Therefore a decision made based on a given dose now,  may

> change later, based on the same dose, as the risk associated with that 

dose

> changes.  Therefore dose correlates to risk only at a given point in time,

>







I understand this to a point, and the point at which I say "huh?" is if EPA

is not assigning the "risk" from the dose, how in the world is it assigning

it?  I mean the inhalation and ingestion HEAST factors are in units of risk

per pCi (of intake), so EPA's saying that they can assign a "risk" to an

intake of a pCi of a radionuclide, and while the risk from the dose the

intake delivers may change, the inherent risk from the intake will not? 

 This

makes no sense to me.



I mean, if a BEIR committee comes out one year and says, "the risk from 25

millirem is a 5E-4 increased risk of cancer over a lifetime," then the next

year says, "the risk from 50 millirem is a 5E-4 increased risk of cancer 

over

a lifetime," then this affects the risk from the intake.  E.g., in the first

case, the risk from an intake of 1 microcurie of Cs-137 is 5E-4, and the 

next

year the risk from an intake of 2 microcuries of Cs-137 is 5E-4.  EPA hasn't

avoided anything from trying to cut dose out of the process because the

intake and dose are intimately related.  Sure, the models will change, as 

our

information and knowledge-base grows, but then both the dose assignment and

risk will change.  You can't avoid the fact that the risk arises from the

dose delivered to the exposed person.  Am I making sense here?



Barbara L. Hamrick

BLHamrick@aol.com



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