[ RadSafe ] Natural gamma rays supposedly linked to childhood leukemia

[radbloom at comcast.net]

Bobby, 



  

Thank you so much for your insight into both the model and its unsupported implications.  

  

Cindy 


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




From: "Bobby Scott" < BScott @ lrri .org> 
To: radsafe @health.phys. iit . edu 
Cc: "Dan McCarn " < hotgreenchile @ gmail .com>, "Mike Brennan ( DOH )" <Mike.Brennan@ DOH .WA.GOV>, "Andy Howard" < howard @phys. iit . edu >, "John E. Dixon (CDC/ ONDIEH / NCEH )" <gyf7@ cdc .gov> 
Sent: Thursday, June 28, 2012 5:20:37 PM 
Subject: [ RadSafe ] Natural gamma rays supposedly linked to childhood        leukemia 

  

Hi All, 

  

I have taken a look at the new paper by G. M. Kendall et al . in the 
Leukemia Journal claiming a link between natural background gamma rays 
and childhood leukemia. The paper is titled "A record-based case-control 
study of natural background radiation and the incidence of childhood 
leukaemia [leukemia] and other cancers in Great Britain during 
1980-2006." Because of the additional radiation-phobia-related 
casualties in Japan that could be promoted by this article, I thought it 
to be important to take a close look at the modeling approach used by 
the researchers.  Of special interest was the mathematical form used for 
relative risk (RR) evaluation and what values of RR would be expected 
based on the RR function used when radiation doses are significantly 
greater than those from natural background.  The authors used an 
exponential form for relative risk , i.e., RR = exp(alpha*dose) for the 
natural background radiation effect. The authors claim that their 
calculated 12% excess relative risk (ERR) of childhood leukemia per mGy 
of cumulative red-bone-marrow dose from natural-background-related gamma 
rays supports the extrapolation of high-dose-rate risk models (e.g., 
based on A-bomb survivors) to low-rate exposure.  A 12% excess relative 
risk per mGy after low-dose, low-rate exposure implies a value of 0.12 
per mGy for the parameter alpha.  With this value, RR for childhood 
leukemia at 100 mGy (similar to the annual dose from natural background 
radiation for the Kerala coast, India) would be calculated to be RR = 
exp(12) = 162,755. For a 200 mGy (20 rad) dose (similar to the annual 
dose from natural background radiation in Ramsar , Iran), RR would be 
calculated to be 26,489,122,130. As I think others may agree, such a 
derived dose-response function for leukemia RR for children raises 
serious questions about the validity of the results of the study of 
Kendall et al . 

  

Best wishes, 

Bobby 

B. R. Scott 

Lovelace Respiratory Research Institute 

2425 Ridgecrest Drive SE 

Albuquerque, NM 87108, USA 

  




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