When the data were analyzed and tabulated, there must have been a number of stunned Johns Hopkins Ph.D.s wondering what had happened. They started out to show the adverse effects of gamma radiation and ended up showing that it enhanced healthfulness.
The first page of the "Summary of Findings" tells the story:
"The all cause mortality is highest for the NNW [Nones] group and lowest for the NW>0.5 [Highs] which certainly does not suggest that radiation causes a general risk of health. In fact, in the NW>0.5 group, the mortality is only 76 percent of that of the general population and is significantly lower than would be expected."
Following these statements are eight pages of possible explanations of what may have happened to give such unexpected results. One suggestion was to use the Lows as the comparison group instead of the Nones, but even this still has the higher exposed group with the lowest overall death rate... not what was expected. An attempt to explain away the unusual with the usual "healthy worker effect" was mentioned, though without much enthusiasm. But nothing in the report even got close to explaining the numbers printed in the report under "Actual Data."
Showing posts with label gamma radiation. Show all posts
Showing posts with label gamma radiation. Show all posts
Monday, March 21, 2016
Friday, February 19, 2016
Effects of Radiation on the Life Span of Mice
Surely if ionizing radiation has beneficial effects on growth rate and the immune system competence of mice, as evidenced by a decreased susceptibility to cancer, it ought to have a positive effect on life span. As several studies demonstrate, this is indeed the case.
A 1983 investigation by J.B. Storer [Storer, J.B., et al. Life shortening [sic] in Balb/C mice following brief protracted, and fractionated exposures to neutrons. Radiation Research, 96, 396, 1983] was cited by Luckey as an example of how hormesis effects are often overlooked by researchers who are expected a bio-negative response from radiation. [Radiation Hormesis, 1981, pp 46, 50.]
The authors ignored a peaking of longevity between 5 and 10 cGy, hopefully not in any attempt to be fraudulent or unethical, but probably because it would have appeared anomalous in terms of the LNT.
It is an earlier study [Sacher, G.A. and Grahn, G. Survival of mice under duration-of-life exposure to gamma rays. Journal of the National Cancer Institute, 32, 277, 1964] - which most certainly gave unintended results - that is of considerable interest to hormesis researchers. Life spans of mice - 90 in a control group, and 90 to 120 in four exposed groups - are plotted in Figure 10 on the basis of daily exposures to cobalt-60 gamma radiation. Exposures, which began 100 days after birth, were continued until the death of the specimen.
Caption for Figure 10 Life Span for Irradiated Mice Source: Sacher, G.A., and Grahn, G. Survival of mice under duration-of-life exposure to gamma rays. I. The dosage-survival relation and lethality function. Journal of the National Cancer Institute, 32, 277, 1964; also ANL Report 6971, 1964, p 94.
Anti-nuclear activists, "animal rightists," and "popular wisdom" would predict dire consequences for test animals subjected to such huge doses of radiation every day of their lives. But this study offers substantial evidence that mice receiving 1,000 times their normal background dose had the longest life spans. [It is my understanding that similar results were reported by a researcher named Searle in 1964, but I have not been able to obtain any more information.] You might recall that, in the earlier discussion of growth rate, the optimum was also 1,000 times normal background.
A 1983 investigation by J.B. Storer [Storer, J.B., et al. Life shortening [sic] in Balb/C mice following brief protracted, and fractionated exposures to neutrons. Radiation Research, 96, 396, 1983] was cited by Luckey as an example of how hormesis effects are often overlooked by researchers who are expected a bio-negative response from radiation. [Radiation Hormesis, 1981, pp 46, 50.]
The authors ignored a peaking of longevity between 5 and 10 cGy, hopefully not in any attempt to be fraudulent or unethical, but probably because it would have appeared anomalous in terms of the LNT.
It is an earlier study [Sacher, G.A. and Grahn, G. Survival of mice under duration-of-life exposure to gamma rays. Journal of the National Cancer Institute, 32, 277, 1964] - which most certainly gave unintended results - that is of considerable interest to hormesis researchers. Life spans of mice - 90 in a control group, and 90 to 120 in four exposed groups - are plotted in Figure 10 on the basis of daily exposures to cobalt-60 gamma radiation. Exposures, which began 100 days after birth, were continued until the death of the specimen.
Anti-nuclear activists, "animal rightists," and "popular wisdom" would predict dire consequences for test animals subjected to such huge doses of radiation every day of their lives. But this study offers substantial evidence that mice receiving 1,000 times their normal background dose had the longest life spans. [It is my understanding that similar results were reported by a researcher named Searle in 1964, but I have not been able to obtain any more information.] You might recall that, in the earlier discussion of growth rate, the optimum was also 1,000 times normal background.
Tuesday, February 16, 2016
Effects of Radiation on Cancer - Leukemia Mortality
Of the myriad varieties of cancer, leukemia is most often considered to be associated with exposure to ionizing radiation, so we'll look at it, first, in an experiment involving 1,000 young adult mice per group (about 12,000 mice in all), which were exposed to a single dose of gamma radiation from 20 to 600 cGy at the rate of 300 cGy (300 rad) per minute. (Ouch.) This experiment was directed by J.R. Maisin and reported in Radiation Research, 113, 300, 1988 (see Figure 7). To realize just how far apart the Linear No-Threshold Theory and the hormesis model are from one another, the LNT predicts a 60% increase in leukemia at an exposure of 200 cGy, while the actual data show a 35% decrease. One can argue all day the beauty of the LNT and how it is a terrific standard for regulatory control; but these data show that it just isn't true when compared to experiment.
Caption for Figure 7: Leukemia Mortality in Mice: Source: Maisin, J.R., Wambersie, A., Gerber, G.B., Mattelin, G., Lambert-Collier, M., and Guelette, J., Life shortening and disease incidence in C57BL mice after single and fractionated gamma and high energy neutron exposure. Radiation Research, 113, 300, 1988.
Caption for Figure 7: Leukemia Mortality in Mice: Source: Maisin, J.R., Wambersie, A., Gerber, G.B., Mattelin, G., Lambert-Collier, M., and Guelette, J., Life shortening and disease incidence in C57BL mice after single and fractionated gamma and high energy neutron exposure. Radiation Research, 113, 300, 1988.
Sunday, February 14, 2016
Who's the Leader of the Gang...
Irradiation of the pregnant animals - and the foetuses in utero caused an astonishing decrease of the mortality rate of the infected baby mice. [Mayr and Paulas, Unexpected effects of a whole body irradiation on the mortality rate of baby mice after an experimental infection with the vesicular stomatitis virus (VSV), Zentralbl. Veterinaermed, 36, 577, 1989.]
As a rule, I don't think much of animal experiments. No, I'm not a member of People for the Ethical Treatment of Animals (PETA); in fact, I think many test animals (that would have never existed were it not for testing requirements) have it a whole lot better than their cousins who live in the wild. Can you th ink of anything worse than being a mouse that is in the process of being swallowed whole by a snake? And besides not having to be constantly on the lookout for snakes, cats, and hawks, some of these test critters have a pretty active social life - especially those involved in reproductive studies.
My problem with much of the animal testing is similar to the problem I have with the LNT - it is based on extrapolation with no consideration of a possible (and likely) threshold. For example, cancer researchers will load up some rat - which has been bred for a propensity to have tumors - with the human equivalent of two boxcars per day of an artificial sweetener, and then declare the substance to be a human carcinogen when a few tumors appear. No consideration is given to the possibility that there is a threshold, above which the rat's resistance is overwhelmed, but below which there is no effect.
Fortunately, mouse experiments related to disproving the LNT and demonstrating hormesis are not in this category. A single datum point on the accompanying graphs is often the average of hundreds of mouse lifetimes, and the curves subsequently drawn lie within the range of these experimental data so that no extrapolation is necessary. Besides most of the tested mice should be happy campers, since ionizing radiation in the hormesis range generally promotes health and longevity.
This chapter will look into the effects of low-level (and a few not so low-level) X-rays and gamma radiation on the mice. Most of it is related to cancer, sinc, as we are aware, this disease is commonly associated with radiation and is, in fact, the major detrimental effect of exposure. Other topics include growth rate, life span, radio-resistance (which all parents of teenagers should have), and one inexplicable effect of radiation received by the parents of the test mice.
In the following studies, exposures (rads/Gy) and doses (rems/Sv) are equal, since only gamma and X-ray radiation are involved.
As a rule, I don't think much of animal experiments. No, I'm not a member of People for the Ethical Treatment of Animals (PETA); in fact, I think many test animals (that would have never existed were it not for testing requirements) have it a whole lot better than their cousins who live in the wild. Can you th ink of anything worse than being a mouse that is in the process of being swallowed whole by a snake? And besides not having to be constantly on the lookout for snakes, cats, and hawks, some of these test critters have a pretty active social life - especially those involved in reproductive studies.
My problem with much of the animal testing is similar to the problem I have with the LNT - it is based on extrapolation with no consideration of a possible (and likely) threshold. For example, cancer researchers will load up some rat - which has been bred for a propensity to have tumors - with the human equivalent of two boxcars per day of an artificial sweetener, and then declare the substance to be a human carcinogen when a few tumors appear. No consideration is given to the possibility that there is a threshold, above which the rat's resistance is overwhelmed, but below which there is no effect.
Fortunately, mouse experiments related to disproving the LNT and demonstrating hormesis are not in this category. A single datum point on the accompanying graphs is often the average of hundreds of mouse lifetimes, and the curves subsequently drawn lie within the range of these experimental data so that no extrapolation is necessary. Besides most of the tested mice should be happy campers, since ionizing radiation in the hormesis range generally promotes health and longevity.
This chapter will look into the effects of low-level (and a few not so low-level) X-rays and gamma radiation on the mice. Most of it is related to cancer, sinc, as we are aware, this disease is commonly associated with radiation and is, in fact, the major detrimental effect of exposure. Other topics include growth rate, life span, radio-resistance (which all parents of teenagers should have), and one inexplicable effect of radiation received by the parents of the test mice.
In the following studies, exposures (rads/Gy) and doses (rems/Sv) are equal, since only gamma and X-ray radiation are involved.
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