[ RadSafe ] Natural gamma rays supposedly linked to childhood leukemia

[Scott, Bobby]

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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