[ RadSafe ] BEIR VII

[ROBBARISH at aol.com]

Dear Colleagues:
 
Before too many of you go overboard about the new BEIR report, I suggest  
that you look at Chapter 12 and, more specifically, do some math with respect to  
the data in tables 12-6 and 12-7. For many years the assumed cancer mortality 
 derived from the LNT model at low-dose rates has been expressed as 4 per 
100,000  individuals exposed to a total of 1 mSv "excess radiation" over their 
lifetime.  This came from applying a dose-dose-rate-effectiveness factor (DDREF) 
 of approximately 1.5 to cancer mortality estimates based on high-dose  
instantaneous exposures. 
 
So 4 per 100,000 per 1 mSv is a number that has been in use for  at least 15 
years to represent excess cancer mortality. Since the "normal"  incidence of 
fatal cancer in our society is 23,000 out of 100,000 individuals  that "excess" 
of 4 is pretty inconsequential. Even if one assumes a dose of 1  mSv over a 
100 year lifetime, the risk becomes 4 in 1,000 with an projected 234  fatal 
cancers instead of 230 expected with no exposure above "normal."
 
If you look at the data in the two tables, one for solid cancer and the  
other for leukemia, and concentrate on the mortality section you can  see the 
values for a 1 mSv exposure per year throughout a persons entire  life. Using the 
"preferred estimates" from the committee, the values of 337 (290  + 47) for 
males and 498 (460 + 38) for females average to just about the same 4  per 
100,000 for a one-hundred year lifetime.
 
Looking at the "adult exposure" rows in these tables, ages 18 to 65, and  
dividing by 10 to get 1 mSv per year as a comparison, the numbers are 170 (141+  
29) for males and 239 (217 + 22) for females which averages to 2.05 over 47  
years, or about the same 4 per 100,000 for 100 years.
 
So despite the hoopla which is being created, the numbers are the same LNT  
values that have been around for at least a decade. This can be confirmed by  
looking at Table 12-8 which shows the comparison with the earlier BEIR V report 
 from 1990. There the numbers are for "excess deaths" for a population of 
100,000  of all ages and both sexes exposed to 100 mSv. The BEIR V number 
adjusted for  DDREF is 460 solid tumors + 95 leukemias = 555 fatalities. The BEIR VII 
numbers  are 510 solid tumors + 61 leukemias = 571 fatalities. Which, of 
course, are  essentially the same values given the large 95% confidence intervals 
on all  of these numbers.
 
So why are we getting upset? Nothing has changed in 15 years. The only  
reason I can think of is that those who are opposed to the use of LNT have not  had 
their objections to that model confirmed in the new report. Also, the press  
seems to love reporting this as something new when, in fact its the same old  
stuff.
 
Regards.
 
Rob Barish, Ph.D. CHP