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View Diary: Radiation, Cancer, and the Linear No-Threshold Model (143 comments)

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  •  3 days ago it was 12cpm (2+ / 0-)
    Recommended by:
    raoul78, LookingUp

    10 to 20 is normal. Without Radon though.....

    FDR 9-23-33, "If we cannot do this one way, we will do it another way. But do it we will.

    by Roger Fox on Thu Mar 17, 2011 at 05:58:30 PM PDT

    [ Parent ]

    •  Well, there are places where (5+ / 0-)

      natural radioactivity is VERY high, and the people who live there are just fine.

      So, when the levels get to be 100x or so above background, then we can start running around with our hair on fire, so to speak

      •  Yeah, this is the intertubes, so (4+ / 0-)
        Recommended by:
        Wee Mama, OtherDoug, LookingUp, Ice Blue

        here are the links, first from Wikipedia:

        The highest levels of natural background radiation recorded in the world is from areas around Ramsar, particularly at Talesh-Mahalleh which is a very high background radiation area (VHBRA) having an effective dose equivalent several times in excess of ICRP-recommended radiation dose limits for radiation workers and up to 200 times greater than normal background level

        then a more detailed account of the impact on health:

        •  Oops, missing link! (0+ / 0-)

          And it was the one I was interested in.  Could you post a follow up comment with the link?  Thanks!

          •  sorry, don't know what happened . . . (3+ / 0-)
            Recommended by:
            OtherDoug, raoul78, Ice Blue
          •  OTOH, this (1+ / 0-)
            Recommended by:
            OtherDoug

            link seems to imply that all of the existing studies on this topic aren't that good . . . .  (I don't have access to any of the complete papers right now)

            In any event, the fact that they aren't conclusive probably tells one that there is no "smoking gun" that proves the linear dose model (for example, if background levels are a hundred times higher in  one area yet cancer is statistically the same - or it requires very sophisticated analysis that has not yet been done to note a difference - clearly the effect is not "linear" since a hundred fold increase in cancer would surely be instantly notable!)

            •  A doubling of cancer risk (5+ / 0-)

              would likely not occur due to radiation - if 100 mSv increases your risk by 0.5%, 1 Sv then would be 1% and 10 Sv would only be a 10% increase - but you'd die of acute radiation sickness much sooner than you could develop cancer from a 10 Sv dose.  

              There simply isn't enough statistical power and population groups to look at these low dose numbers, so the LNT model predicts these effects for doses below what we can statistically detect.

              These high dose areas, like in Iran, should see statistical increases in cancer risk, but even then, since the population is relatively low, and cancer risk is already quite high, the signal-to-noise ratio puts the increase below the detection limit.  

              •  The Kerala, India "high" radiation region (3+ / 0-)
                Recommended by:
                raoul78, OtherDoug, Ice Blue

                seems to have been subject to a bit more rigorous study:

                abstract from PUBMED

                The coastal belt of Karunagappally, Kerala, India, is known for high background radiation (HBR) from thorium-containing monazite sand. In coastal panchayats, median outdoor radiation levels are more than 4 mGy y-1 and, in certain locations on the coast, it is as high as 70 mGy y-1. Although HBR has been repeatedly shown to increase the frequency of chromosome aberrations in the circulating lymphocytes of exposed persons, its carcinogenic effect is still unproven. A cohort of all 385,103 residents in Karunagappally was established in the 1990's to evaluate health effects of HBR. Based on radiation level measurements, a radiation subcohort consisting of 173,067 residents was chosen. Cancer incidence in this subcohort aged 30-84 y (N = 69,958) was analyzed. Cumulative radiation dose for each individual was estimated based on outdoor and indoor dosimetry of each household, taking into account sex- and age-specific house occupancy factors. Following 69,958 residents for 10.5 years on average, 736,586 person-years of observation were accumulated and 1,379 cancer cases including 30 cases of leukemia were identified by the end of 2005. Poisson regression analysis of cohort data, stratified by sex, attained age, follow-up interval, socio-demographic factors and bidi smoking, showed no excess cancer risk from exposure to terrestrial gamma radiation. The excess relative risk of cancer excluding leukemia was estimated to be -0.13 Gy-1 (95% CI: -0.58, 0.46).
        •  Thats partially why I wrote this diary (5+ / 0-)

          Natural radiation varies tremendously, and numbers such as 200 times greater than normal don't convey much real information.  

          In Ramsar Iran for example, maximum reported doses average over a year come to around 30 microsieverts/hour, levels that are 100s of times higher than normal background in Japan.  

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