The Environmental Test Lab II

The unfortunate Japanese cities of Hiroshima and Nagasaki provide us with a test lab without peer. Thousands of citizens of all ages were exposed to different amounts of radiation in a very short period of time. From their locations at the time of the blast, their exposures could be determined with relative accuracy. Moreover, they were expected to carry and update their health records. As has been shown, the exposed survivors had unexpectedly longer and healthier lifetimes than did their unexposed cohorts.

But there is now a laboratory for low-level radiation absorbed over a period of twenty years. From 1982 to 1984, about 180 apartment buildings housing 10,000 Taiwanese tenants were built with cobalt-60-contaminated steel (half-life of 5.3 years). Since, as we all know, radiation causes cancer, these unfortunates must be dying like flies.

Well, not exactly. The assessed cancer rate of occupants of the apartments is 3.5 deaths per 100,000 person-years. The average death rate of the general population over the same twenty-year period is 116 persons per 100,000 person-years - resulting in a 97% reduction of fatal cancer.

Have you heard about this story on Headline News? No? Well, maybe no one is interested in reducing his risk of cancer by ninety-seven percent. But just in case you are, you may want to take a look at a paper entitled, "Is Chronic Radiation an Effective Prophylaxis Against Cancer?" [Chen, W.L., Luan, Y.C., et al., "Is Chronic Radiation an Effective Prophylaxis Against Cancer?" Journal of American Physicians and Surgeons, Vol. 9, No. 1, Spring 2004. Taiwanese officials have resisted providing information needed for a first rate epidemiological report, apparently embarrassed that their LNT predictions didn't pan out.]

Effects of Radiation on Cancer in Mice - Lung Cancer Mortality

There are three studies that address the effects of ionizing radiation on lung cancer mortality in mice. The most recent of these was a 1997 experiment by Y. Hosoi and K. Sakamoto [Suppression of spontaneous and artificial tumors by low dose total body irradiation in mice. In Low Doses of Ionizing Radiation: Biological Effects and Regulatory Control, Atomic Energy Agency, TECDOC-976, Vienna, 1997] in which mice were injected with artificial metastases (a fancy medical term for cancer cells) and then irradiated with gamma rays up to 100 cGy (100,000 mrad). Data showed the lowest cancer rate in a range between 15 and 40 cGy, with the minimum being 41% of controls at 15 cGy.

The Hosoi-Sakamoto study demonstrated another tenet of the hormesis theory, however, which most other experimenters have neglected to investigate - namely that hormesis is a property of the organism and not its individual cells. When tumor cells that had been irradiated with 10 to 50 cGy gamma rays in vitro were injected in the mice, there was no difference from the controls - indicating that the suppression affects the mouse, not tumor cells. Unfortunately, the study involved only 200 - 250 mice (perhaps they are scarce in Japan?) and lacks the statistical significance I would like to see for compelling evidence.

Both of the lung cancer experiments were performed by Ullich et al., whom we have seen laboring earlier with mouse pituitaries; and both experiments involved several thousand mice. His 1977 investigation [Ullrich, R.L., et al. Neutron carcinogenesis. Dose and dose-rate effects in BALB.C mice. Radiation Research, 72, 487, 1977], which showed a minimum lung cancer mortality in the area of 100 cSv, was repeated in 1979 [Ullrich, R.L., et al. Influence of irradiation on the development of neoplastic disease in mice. Radiation Research, 80, 135, 1979]. This time, instead of only two data points, six were examined from 10 to 300 cSv. As shown in Figure 9, the minimum appeared around 25 cSv in the 1979 data but was still significantly lower than controls even at the 100 cSv level.

At the risk of sounding repetitive, it is evident that the LNT is completely inadequate to explain this phenomenon, while the hormesis theory predicts just such an occurrence.

Caption for Figure 9 Lung Cancer Mortality in Mice Source: Ullrich, R.L., Jernigan, M.C., and Storer, J.B. Neutron carcinogenesis. Dose and dose-rate effects in BALB/C Mice, Radiation Research, 72, 487, 1977. Also Ullrich, R.L., and Storer, J.B. Influence of irradiation on the development of neoplastic disease in mice. I. Reticular tissue tumors. II. Solid tumor. III. Dose-rate effects. Radiation Research, 80, 135, 1979.