Thursday, May 14, 2009

Ionizing Radiation and Childhood Leukemia

by Abel Russ

(of the George Perkins Marsh Institute, Worcester, Massachusetts
The author declares he has no competing financial interests.)

I read with interest the recent review by Belson et al. (2007) on childhood leukemia, particularly the sections dealing with radiation exposure. Like the authors, I believe that ionizing radiation is strongly associated with childhood acute leukemia. I would like to point out that several critical pieces of information were overlooked; these support stronger and more meaningful conclusions.
Although atomic bomb survivors offer the clearest evidence of leukemia risk after childhood exposures to ionizing radiation, studies of children exposed to fallout in other contexts should not be downplayed. Belson et al. (2007) stated that “radiation exposure secondary to the Chernobyl accident has not been shown to increase the risk of leukemia in children who were exposed after birth …,” but they failed to mention the case–control study of Noshchenko et al. (2002), which found significant increases in childhood and acute leukemias in association with estimated childhood exposures. Children living downwind of the Nevada Test Site have also shown a significant increase in leukemia related to estimated fallout exposure (Stevens et al. 1990).

In utero exposure to ionizing radiation has been a known causal factor for childhood cancer for > 50 years. Although Belson et al. (2007) stated that the lack of evidence for a childhood leukemia risk among atomic bomb survivors constitutes the “most notable reason for doubt of a true association,” they overlooked the reviews of Wakeford and Little (2002, 2003); these authors demonstrated that the highly uncertain atomic bomb survivor data are statistically compatible with the robust set of data found in the Oxford Survey of Childhood Cancers and related X-ray exposure cohorts. There is no valid reason to doubt this association at present.

Read the rest of this article, and see footnotes and credits, here:

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