RE: HEAST risk estimates

["Efird, Carl R. (O7K) " <o7k@bechteljacobs.org>]

The risk calculated using the HEAST slope factors is the cancer
incidence over the lifetime of the exposed individual.  Your calculated
risk of 3.84 indicates that the individual is expected to have 3.84
cancers over their lifetime.  For large risk values ( greater that
0.01), the probability of incidence a cancer is calculated using the
one-hit risk equation: 1-exp(-risk).  For small risk values (less than
0.01), the probability of incidence a cancer is approximately equal to
the calculated risk.  When a calculated risk exceeds 1, the cancer
incidence may be unimportant compared to acute effects and the dose
should be calculated to put this in perspective.  

Carl Efird
Email: efirdcr@bechteljacobs.org

> -----Original Message-----
> From:	Anthony Barber [SMTP:a.barber@qut.edu.au]
> Sent:	Thursday, May 14, 1998 2:50 AM
> To:	Multiple recipients of list
> Subject:	HEAST risk estimates
> 
> Can anyone explain what the qualifier (denominator) is for the risk
> measure
> used in the HEAST radionuclide carcinogenicity table?
> 
> Example - risk of contracting cancer from ingestion of Ac89 is given
> as
> 1.42E-10 risk per pCi or 3.84 risks for 1GBq ingested.
> What is 3.84 risks? Is it 3.84%? or is it 3.84 cancers per million
> people
> exposed or maybe it is 3.84 cancers per person exposed? (ha, ha)
> 
> I have read all the documents at the HEAST web page with no joy.
> Although
> it is highly likely that I am simply displaying my ignorance or
> inablity to
> comprehend documents.
> 
> All explanations gratefully accepted.
> 
> Regards
> 
> 
> Anthony Barber
> RSO - Queensland University of Technology
> ph  61 7 3864 3566
> fax 61 7 3864 3993
> a.barber@qut.edu.au
> ******************************
> Why not?
> ******************************