Friday, March 15, 2013

"Study: Radiation for Breast Cancer Can Harm Hearts, But Risk is Small"

by Marilynn Marchione (AP) (2013, March 14) The Arizona Republic, p. A3:

[Excerpted] "Women treated with radiation for breast cancer are more likely to develop heart problems, even with lower doses used today, troubling new research suggests. The risk comes from any amount of radiation, starts five years after treatment and lasts for decades, doctors found...

radiation can hurt arteries, making them prone to harden and clog and cause a heart attack...." [end]

Majia here: To repeat: "the risk comes from any amount of radiation" and occurs because radiation hardens arteries. The risks from exposure to additional levels of ionizing radiation are not restricted to cancer.

Other research has confirmed that “low doses” of radiation pose risks unexpected by the dose-effect models, such as the ICRP. A study published in The Lancet in 2012 found that CT scans cause a small but significant increased risk for leukemia and brain cancer.[i] Two to three scans of the head for children under three tripled the risk for brain cancer as compared to the general population while five to ten scans tripled the risk for leukemia.

A study of adults found that “For every 10 mSv of low-dose ionizing radiation, there was a 3% increase in the risk of age- and sex-adjusted cancer over a mean follow-up period of five years (hazard ratio 1.003 per millisievert, 95% confidence interval 1.002–1.004).[ii]

Finally, recent research has documented that even background levels of radiation can cause cancer in sensitive populations, such as children. One study addressing background gamma radiation found a twelve percent increase in childhood leukemia for every millisievert of natural gamma-radiation does to bone marrow.[iii]This study demonstrates that low dose gamma radiation can produce genetic changes significant enough to cause leukemia.

Taken together these studies demonstrate that common forms of exposure to ionizing radiation can cause cancer and leukemia and that genetic damage can be transmitted across generations. Moreover, they demonstrate that children are particularly susceptible to detrimental effects. The studies are significant because they suggest that current estimates for dose-risks may under-estimate actual risks by not adequately assessing dose-effects on internal organs from internal emitters, such as radioisotopes like cesium and uranium.

For example, the 2006 BEIR report on the Health Risks from Exposure to Low Levels of Ionizing Radiation produced by the National Research Council of the National Academies introduces uncertainty in risk calculations based on internal exposure and on the effects of protracted low-dose exposure.[v] The report notes that ingested alpha particles are more effective than low LET radiation (e.g., gamma rays) in producing genomic instability and that “at low doses, the effectiveness per unit absorbed dose of standard X-rays may be about twice that of high-energy photons.[vi]

[i]           Mark S Pearce, Jane A Salotti, Mark P Little, Kieran McHugh, Choonsik Lee, Kwang Pyo Kim, Nicola L Howe, Cecile M Ronckers, Preetha Rajaraman,
Sir Alan W Craft, Louise Parker, Amy Berrington de González. Radiation exposure from CT scans in childhood and subsequent risk of eukaemia and brain tumours: a retrospective cohort study. The Lancet. June 7, 2012DOI:10.1016/S0140-6736(12)60815-0,

[ii]           Mark J. Eisenberg, Jonathan Afilalo, Patrick R. Lawler, Michal Abrahamowicz, Hugues Richard, and Louise Pilote. Cancer risk related to low-dose ionizing radiation from cardiac imaging in patients after acute myocardial infarction. Canadian Medial Association Journal 183.4 2011, 430-436.

[iii]          Natural gamma rays linked to childhood leukaemia. University of Oxford (2012, June 12)

[iv]          Lucy Forster, Peter Forster, Sabine Lutz-Bonengel Horst Willkomm, Bernd Brinkmann Natural radioactivity and human mitochondrial DNA mutations PNAS

[v]               Committee to Assess Health Risks from Exposure to Low Levels of Ionizing Radiation, National Research Council. Health Risks from Exposure to Low Levels of Ionizing Radiation:BEIR VII p. 276,

[vi]              Committee to Assess Health Risks from Exposure to Low Levels of Ionizing Radiation, National Research Council. Health Risks from Exposure to Low Levels of Ionizing Radiation:BEIR VII p. 70.

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