--- Dan Minette <[EMAIL PROTECTED]> wrote: <snippage> > > The point is that radiation has been around much > longer than humans. It is > a natural part of our environment. In order to > remain healthy we must > ingest potassium, which is radioactive.
This abstract claims that low-dose radiation enhances health: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10453435&dopt=Abstract [If you click on _Related Articles_ at the upper right, other articles on 'ionizing radiation hormesis' are retrieved, including this one which states: "...Accordingly, evolutionary and ecological considerations suggest two components of hormesis in relation to ionizing radiation: background radiation hormesis based upon the background exposure to which all organisms on earth are subjected; and stress-derived radiation hormesis. Exposure under stress-derived radiation hormesis is considerably larger than under background radiation hormesis, so significant deleterious effects from non-catastrophic radiation normally may be impossible to detect..."] http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10715607&dopt=Abstract *Hormesis is "any physiological effect that occurs at low doses and which cannot be anticipated by extrapolating from toxic effects noted at high doses." > The changes in background radiation from human > activity is far smaller than > the natural variation in background radiation. > Since we do not see a > correlation between this natural variation and > genetic damage, health > risks, etc., we can set a fairly low limit to the > risks from low level radiation. A PubMed search yields a 1999 Chinese study that finds a significant increase in esophageal cancer, but no other kinds, in an area of high background radiation: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11715418&dopt=Abstract (A later revision reports no difference; a problem with many studies in this category - including the Chinese ones - is using *estimates* instead of actual measurements -- but clearly accuracy would be difficult to achieve on a population scale...) A 1987 Indian study reports "...Where the radiation level is greater, cancer risk is invariably less. The annual cancer incidence rate (per 100,000 population) seems to decrease by 0.03/microSv increase in the external background radiation dose from a hypothetical incidence level of 79 per 100,000 corresponding to "zero environmental radiation"." http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=3570803&dopt=Abstract [Problem: "seems" and "hypothetical"] > In addition, we can set a > correspondingly lower limit to the > damage done by the very small increase in background > radiation due to human activities. But local excesses in workers, miners and inhabitants where contamination of water/soil has occurred is real. Here is a file about the possible effects of radiation from flying (of concern to frequent flyers and flight crew, as well as pregnant women during a solar particle event), with tables for various flights, from the Jan 2000 _Nuclear News_: http://www.ans.org/pubs/magazines/nn/pdfs/2000-1-3.pdf This 2002 article found an increase in melanoma in Swedish airline pilots and other skin cancers in military pilots: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11817615&dopt=Abstract > Now, there are acute instances of very high > exposures; and those can cause > damage. Being near a nuclear bomb when it goes off > can kill you in many > ways. Radiation damage is one of the least likely > (unless you count being > burnt by the flash as radiation damage), but it does > exist. However, it no > more reasonable to use the danger posed by nuclear > weapons as an argument > against nuclear power than it is to use the dangers > of napalm to argue against oil as an energy source. It's the *waste* that's the problem. It has to be kept from the environment and future human activity for thousands of years. {I looked for a more precise figure on several US gov't sites, but couldn't find it. Here is the NRC's site on high-level waste - I didn't include the Sierra Club's, which gave as a half-life for depleted uranium 4.5 billion years...) http://www.nrc.gov/waste/hlw-disposal.html Ah - from the Nuclear Energy Agency's (France) site: "...it takes about 10,000 years for the radioactivity of such wastes to decay to the level which would have been generated by the original ore from which the nuclear fuel was produced, should this ore never have been mined..." http://www.nea.fr/html/brief/brief-03.html So even if we cut that in half, high-level waste needs to be stored for **5,000 years**. And the "tailings pile [from mining the uranium] must have a cover designed to control radiological hazards for a minimum of 200 years and for 1,000 years to the greatest extent reasonably achievable." http://www.em.doe.gov/idb97/chap5.html About Yucca Mountain: http://www.nei.org/index.asp?catnum=2&catid=197 Couple of problems I have with this "proof:" -dismissal of fast-track leaks -assuming that rainfall will be stable for the next years (if global warming continues, that may well be invalid) -assumption of stability in a seismically active area -assuming what they build will remain intact for 5K years -assuming that humans will be able to keep track of this site for 5K years (heck, we can't even keep track of stuff like asbestos - here in Denver they built a community on the former Lowery AFB site; now they've found both asbestos and chemical agent bomlets (similar to the equally "surprise!" ones at the Rocky Mountain Weapon Arsenal) in this 'ideal community') More medical angles: Data on fetal exposure to X-rays: it is generally agreed that cumulative < 5 rads is "safe" for the fetus WRT major birth defects like microcephaly, although there is a slight increase in risk of leukemia with as little as 1 rad: http://www.aafp.org/afp/990401ap/1813.html "...Exposure to as little as 1 or 2 rad has also been associated with a slight increase in childhood malignancies, especially leukemia. For example, the background rate of leukemia in children is about 3.6 per 10,000. Exposure to one or two rad increases this rate to 5 per 10,000. While these doses do fall within the range of that supplied by some radiographic studies, the absolute increase of risk (about one in 10,000) is very small..." However, there seems to be damage to DNA with a very low dose equivalent to ~ 20 chest X-rays; there is an exposure threshold of 'pretty good cell repair' but below this level DNA damage takes much longer to repair: "...researchers noted that the damage from low radiation levels lingered days to weeks longer than damage induced by more powerful levels..." http://www.abc.net.au/science/news/stories/s820717.htm [Caveats re: this 2003 study: while good, it used cell cultures -- I suspect our skin provides some additional protection, as it has evolved to deal with background radiation. But this would make me even more cautious with pregnancy and diagnostic X-rays, WRT the 1999 AFP article above. --DH] Ionizing radiation (X- and gamma rays), including that from diagnostic procedures (vs. bomb-fallout or *XRT for cancer therapy, which have long had known carcinogenesis), has been proposed by the International Agency for Research on Cancer (IARC) to be included on the Eleventh Report on Carcinogens: http://ntp-server.niehs.nih.gov/htdocs/Liason/RoC11NewNomsFR.html I'll have to read more from this guy before I make up my mind about his veracity, but his credentials are pretty darn good, and he states, "By any reasonable standard of biomedical proof, the evidence from human epidemiology and the physical evidence from track-analysis combine to demonstrate that cellular repair processes, for nuclear DNA and chromosome injuries, are unable to deliver a safe (risk-free) dose of low-LET radiation --- including x-rays and gamma-rays." (Part 4 of this site) http://www.ratical.com/radiation/CNR/XHP/NTP.html WRT workers at Oak Ridge Nat'l. Lab: "...These findings suggest increases in cancer mortality associated with low-level external exposure to ionizing radiation and potentially greater sensitivity to the carcinogenic effects of ionizing radiation with older ages at exposure." http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10417363&dopt=Abstract A synergystic effect of tobacco smoking and radiation exposure was noted in several of the sites above, and others as well (I didn't cite b/c that doesn't seem to be in dispute). It appears that the jury is still out on very-low dose exposure; this is the most recent summary I could find on hormesis (out in June 2003): "The ongoing debate over the possible beneficial effects of ionising radiation on health, hormesis, is reviewed from different perspectives. Radiation hormesis has not been strictly defined in the scientific literature. It can be understood as a decrease in the risk of cancer due to low-dose irradiation, but other positive health effects may also be encompassed by the concept. The overwhelming majority of the currently available epidemiological data on populations exposed to ionising radiation support the assumption that there is a linear non-threshold dose-response relationship. However, epidemiological data fail to demonstrate detrimental effects of ionising radiation at absorbed doses smaller than 100-200 mSv. Risk estimates for these levels are therefore based on extrapolations from higher doses. Arguments for hormesis are derived only from a number of epidemiological studies, but also from studies in radiation biology. Radiobiological evidence for hormesis is based on radio-adaptive response; this has been convincingly demonstrated in vitro, but some questions remain as to how it affects humans. Furthermore, there is an ecologically based argument for hormesis in that, given the evolutionary prerequisite of best fitness, it follows that humans are best adapted to background levels of ionising radiation and other carcinogenic agents in our environment. A few animal studies have also addressed the hormesis theory, some of which have supported it while others have not. To complete the picture, the results of new radiobiological research indicate the need for a paradigm shift concerning the mechanisms of cancer induction. Such research is a step towards a better understanding of how ionising radiation affects the living cell and the organism, and thus towards a more reliable judgement on how to interpret the present radiobiological evidence for hormesis." http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12719923&dopt=Abstract [Aside re: radon exposure: it certainly causes lung cancer in uranium miners, but at least one study found no increase in inhabitants of a high-radon area of Japan] http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11135223&dopt=Abstract http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1544865&dopt=Abstract Debbi who is quitting now because her brain hurts Brazil Nuts Are Worse Than Bananas! Maru http://www.physics.isu.edu/radinf/natural.htm (food table just past halfway-down) __________________________________ Do you Yahoo!? Yahoo! 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