RE: EPA, risk and dose

["Stokes, James" <StokesJ@TTNUS.COM>]

 I am going to qualify that I do NOT speak for the U.S. EPA, and the

following is my understanding of the policy position on dose vs risk.



We are a contractor that performs CERCLA risk assessment traing for the U.S.

EPA.  In our course material, which is approved by the U.S. EPA, presents it

this way.  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,

and therefore is not an absolute value.



I am not a risk assessor, and I would like anyone who is a risk assessor,

especially a CERCLA one, provide any clarification or further explaination

of what I have said.



jim Stokes RRPT



- -----Original Message-----

From: BLHamrick@AOL.COM

To: radsafe@list.vanderbilt.edu

Sent: 3/28/01 9:53 PM

Subject: EPA, risk and dose



I have a question - possibly a few.  Please don't laugh.  I have been

reading 

EPA's guidance on CERCLA evaluations at NRC licensed or decommissioned

sites. 

 I repeatedly run into statements by the EPA that they should not be 

evaluating potential dose, but rather potential risk, using their HEAST 

factors.  Here comes my question(s): 



If there is no dose, there is no risk, right?....So, how does one

estimate 

risk, with blinders on to dose?  I mean, an agency can ask to express a

limit 

in certain units, and if EPA likes risk over dose, then fine, but they

seem 

to imply you can't easily relate the two, and that where I have a

problem, 

because if you're not imparting energy to human tissue (delivering

dose), 

then there is no risk, so either there is a definable relationship

between 

the two, so that you can convert between dose and risk, or there is not,

in 

which case you can only speak about dose (which is measurable).

Otherwise 

where in the heck are the risk numbers coming from? 



Also, in a back of the envelop (literally) calculation comparing EPA's

"risk" 

factors to dose (heaven forbid), I find that their factor for inhalation

of 

C-14 would put their upper-bound of acceptability (i.e., an increased 

lifetime risk of cancer at 10E-4) at about 35 rem over an average

occupancy 

of 30 years (if you use the ALIs in 10 CFR 20 to convert intake to

dose), or 

about 1.2 rem per year...Is this, possibly, why they don't want to talk

dose? 



Just respectfully wondering. 



Barbara L. Hamrick 

BLHamrick@aol.com

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