Wednesday, November 21, 2012

More Evidence Low Level Radiation Not Safe


Majia here: Below please see a series of articles documenting health effects from "low" and "moderate" levels of exposure to ionizing radiation. 

Hat tip: Thanks Craig for the links!


Systematic Review and Meta-Analysis of Circula­tory Disease from Exposure to Low-Level Ionizing Radia­tion and Estimates of Potential Popula­tion Mortality Risks by Mark P. Little et al, http://ehp.niehs.nih.gov/2012/11/1204982/
[excerpted from abstract] Background: Although high doses of ionizing radia­tion have long been linked to circula­tory ­disease, evidence for an associa­tion at lower exposures remains controversial. However, recent analy­ses suggest excess relative risks at occupa­tional exposure levels.


Objectives: We performed a systematic review and meta-analy­sis to summarize informa­tion on circula­tory disease risks associated with moderate- and low-level whole-body ionizing radia­tion exposures.


Conclusions: Our review supports an associa­tion between circula­tory disease mortality and low and moderate doses of ionizing radia­tion. Our analy­sis was limited by heterogeneity among studies (particularly for noncardiac end points), the possibility of uncontrolled confounding in some occupa­tional groups by lifestyle factors, and higher dose groups (> 0.5 Sv) generally driving the observed trends. If confirmed, our findings suggest that overall radia­tion-related mortality is about twice that currently estimated based on estimates for cancer end points alone (which range from 4.2% to 5.6%/Sv for these popula­tions).
 [end excerpt]

Chernobyl Cleanup Workers Had Significantly Increased Risk of Leukemia Findings May Help Estimate Cancer Risk from Low-Dose Exposures like CT Scans By Jason Bardi on November 8, 2012 http://www.ucsf.edu/news/2012/11/13087/chernobyl-cleanup-workers-had-significantly-increased-risk-leukemia
[Excerpted] A 20-year study following 110,645 workers who helped clean up after the 1986 Chernobyl nuclear power plant accident in the former Soviet territory of Ukraine shows that the workers share a significant increased risk of developing leukemia. The results may help scientists better define cancer risk associated with low doses of radiation from medical diagnostic radiation procedures such as computed tomography scans...

In the journal Environmental Health Perspectives this week, an international team led by scientists at the University of California, San Francisco (UCSF) and the Chernobyl Research Unit at the Radiation Epidemiology Branch of the National Cancer Institute describes the increased risks of leukemia among these workers between 1986 and 2006. The risk included a greater-than-expected number of cases of chronic lymphocytic leukemia, which many experts did not consider to be associated with radiation exposure in the past. 
The new work is the largest and longest study to date involving Chernobyl cleanup workers who worked at or near the nuclear complex in the aftermath of the accident...

SEE ALSO
Even Low-Level Radioactivity Is Damaging, Scientists Conclude. Science Daily. November 13, 2012 http://www.sciencedaily.com/releases/2012/11/121113134224.htm
[Excerpted] The organisms studied included plants and animals, but had a large preponderance of human subjects. Each study examined one or more possible effects of radiation, such as DNA damage measured in the lab, prevalence of a disease such as Down's Syndrome, or the sex ratio produced in offspring. For each effect, a statistical algorithm was used to generate a single value, the effect size, which could be compared across all the studies.

The scientists reported significant negative effects in a range of categories, including immunology, physiology, mutation and disease occurrence. The frequency of negative effects was beyond that of random chance.

"There's been a sentiment in the community that because we don't see obvious effects in some of these places, or that what we see tends to be small and localized, that maybe there aren't any negative effects from low levels of radiation," said Mousseau. "But when you do the meta-analysis, you do see significant negative effects."

"It also provides evidence that there is no threshold below which there are no effects of radiation," he added. "A theory that has been batted around a lot over the last couple of decades is the idea that is there a threshold of exposure below which there are no negative consequences.
These data provide fairly strong evidence that there is no threshold -- radiation effects are measurable as far down as you can go, given the statistical power you have at hand." Mousseau hopes their results, which are consistent with the "linear-no-threshold" model for radiation effects, will better inform the debate about exposure risks. " 

FOR DISCUSSION SEE WASHINGTON'S BLOG HERE

ADDITIONALLY: 

Excess Lupus Cases Found Near Uranium Plant By Nancy Walsh, Staff Writer, MedPage Today Published: November 16, 2012 Reviewed by Zalman S. Agus http://www.medpagetoday.com/MeetingCoverage/ACR/35987
[Excerpted] Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal. In this study, a significant association was found between exposure to high levels of uranium and systemic lupus erythematosus, but not rheumatoid arthritis. People living in an area contaminated by a uranium processing plant had up to a 5-fold risk of developing systemic lupus erythematosus, researchers found.

The exact mechanism that links uranium radiation to lupus is unknown, Lu said, but animal studies have shown that uranium can mimic effects of estrogen, and estrogen is being studied as a factor in the development of lupus."There appears to be a relationship between living near a uranium processing plant and development of lupus. Certainly more research is going to be necessary to understand this relationship," she said. She told MedPage Today that other factors, such as the chemicals used in the processing of the uranium at the plant, could also be at work.[end quote]

SEE PREVIOUS POSTS

Majia's Blog: BURDENING THE SPECIES WITH GENETIC ...May 23, 2012



Jul 02, 2012
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Feb 22, 2012
Spontaneous mutant frequency in the male germline increases with age, thereby increasing the risk of siring offspring with genetic disorders. In the present study we investigated the effect of age on ionizing radiation-induced ...
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Their position conflicted with the “threshold” theory still promoted by the AEC that held that ionizing radiation did not cause harmful somatic or genetic effects below a specific threshold. The critics charged that Goffman and ...

 

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