Before we start, I would like to restate that there is no scientific evidence whatsoever that health risks can be measured by total radiation dose alone. It is a complicated subject since it depends on the type of radiation emitted, whether it is internal or external to the body, what the chemical element is – Iodine, Uranium etc. Also, since diseases such as cancer depend on a number of risk factors, the risk of will also depend on what other risk factors there are.
Because of the exact details, a model is used. However, this is known to be seriously flawed.
….. There are important concerns with respect to the heterogeneity of dose delivery within tissues and cells from short-range charged particle emissions, the extent to which current models adequately represent such interactions with biological targets, and the specification of target cells at risk. Indeed, the actual concepts of absorbed dose become questionable, and sometimes meaningless, when considering interactions at the cellular and molecular levels.
Committee Examining Radiation Risk of Internal Emitter Majority Report Chapter 2.1 paragraph 11
This leads to many contradicting results. Some of this is because the studies are flawed, but often because the underlying dose-risk model is inadequate.
Natural Background Radiation
I have often seen it argued that since we have been living with natural background radiation (about 2mSv per year) that have adapted to this and it poses no risk. Rather like we have lived with malaria or that sparrows have lived with sparrowhawks, and therefore they pose no risk.
This idea is totally unsupported by any scientific evidence. It is strange that many pro-nuclear people become complete waftey hippies claiming that because something is ‘natural’ it is fine. In fact, naturally occurring radon
“is the second leading cause of lung cancer in the United States and is associated with 15,000 to 22,000 lung cancer deaths each year.”
Radon and Cancer: Questions and Answers – National Cancer Institute (USA), National Cancer Institute
About 20% of childhood leukaemia in Great Britain has been attributes to background radiation1. The theoretical estimates show that 16 % of lung cancer deaths among Canadians are attributable to indoor radon exposure2.
As ‘Safe’ As Naturally Occurring Uranium
Sometimes you will here or see statements such as ‘after X years it will decay until the radiation levels are the same as natural uranium’. What this invariably refers to is that the radiation levels are the same as refined uranium metal.
However, Uranium metal does not occur naturally. In fact, a good uranium source for mining is usually less than 0.2% Uranium. There are a couple of exceptions in Canada which are 25%. However, the ore is blended with other rock to decrease the risk to workers.
Uranium ore deposits are also in the form of solid rock. The health risks to this cannot be compared with ore which has been crushed. Even worse, it is often chemically treated to make it more soluble.
Thirdly, these rocks tend to be underground and not on the surface.
So if they really want such things as depleted uranium or mining waste to be as ‘safe as naturally occurring Uranium’ it should be mixed with other rock (1 part Uranium to 500 parts rock), turned into a stable rock like substance and then buried deep underground.
1 The proportion of childhood leukaemia incidence in Great Britain that may be caused by natural background ionizing radiation.
Wakeford R, Kendall GM, Little MP (http://www.ncbi.nlm.nih.gov/pubmed/19151785).
2 Canadian population risk of radon induced lung cancer: a re-assessment based on the recent cross-Canada radon survey J. Chen*,D. Moir an dJ. Whyte (http://rpd.oxfordjournals.org/content/152/1-3/9.full)
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