[ RadSafe ] Natural gamma rays supposedly linked tochildhood leukemia

[Scott, Bobby]

Socio-economic status was also considered. Cumulative radiation equivalent dose to bone marrow was used as an independent variable. Cumulative radiation equivalent dose (or absorbed dose) as an independent variable can be problematic for studies of possible effects of exposure of children to natural background radiation since any stochastic biological effect (e.g., cancer) that evolves over time after birth would be expected to correlate with time living as a child, irrespective of the actual cause of the biological effect (e.g., something other than radiation). The cumulative radiation dose from natural radiation increases as the time living increases. Thus, case-control-study findings such as indicated by Kendall et al. may simply be reflecting a correlation between cumulative radiation dose and time living as a child.
 
Bobby
B.R. Scott


________________________________

From: Ludwig E. Feinendegen [mailto:feinendegen at gmx.net]
Sent: Fri 6/29/2012 2:55 AM
To: 'The International Radiation Protection (Health Physics) Mailing List'
Subject: Re: [ RadSafe ] Natural gamma rays supposedly linked tochildhood leukemia



Thank you, Bobby.  You have led the authors ad absurdum!  I believe, that
the paper would not have been accepted for print if it would not serve the
radiation phobia universe. Does Kendall's paper also suffer from a lack of
paying attention to confounding factors that may differ regionally?  Was the
background radiation level the only variable in their regional analyses?
Unfortunately, I have not been able to get the full paper.  Best, Ludwig


-----Ursprüngliche Nachricht-----
Von: radsafe-bounces at health.phys.iit.edu
[mailto:radsafe-bounces at health.phys.iit.edu] Im Auftrag von Scott, Bobby
Gesendet: Donnerstag, 28. Juni 2012 23:21
An: radsafe at health.phys.iit.edu
Cc: Dan McCarn; Brennan, Mike (DOH); Andy Howard; Dixon, John E.
(CDC/ONDIEH/NCEH)
Betreff: [ 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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