CANCER PREVENTION BY RADIATION
Radiation, Science, and Health, Inc., P. O. Box 843, Needham, MA 02194, has been compiling data on the health effects of low-level radiation under the guidance of its Board of Directors, which includes many prominent researchers in this field. Included in their February 1997 draft compilation are Figures 1 and 2.
Figure 1 is from Bogen, K. T., "A Cytodynamic Two Stage Model That Predicts Radon Hormesis (Decreased, then Increased Lung-Cancer Risk vs. Exposure),'' Lawrence Livermore National Laboratory, University of California, Preprint UCRL-TC-123219, and is based upon the data of B. L. Cohen, "Test of the linear-no threshold theory of radiation carcinogenesis for inhaled radon decay products,'' Health Physics 68, p 157-174. Figure 2 is from Kendall, G. M., et al., "Mortality and occupational exposure to radiation; first analysis of the National Registry for Radiation Workers,'' British Medical Journal 304, p 220 (1992).
The line labeled "BEIR IV'' in Figure 1 corresponds to the discredited no-threshold linear hypothesis, while the line labeled "CD2'' conforms to the experimental data which shows the hormesis discovered by Cohen. Up to a level of about 6 pCi/L, residential radon is seen to lower the risk of lung cancer. Cohen does not provide data above the levels shown, so this theoretical curve is drawn to conform to the expected deleterious effects of radon at higher levels - estimated here to be above 10 pCi/L.
Cohen's comprehensive work, which we have discussed in several earlier issues of Access to Energy, shows quite clearly that inhalation of radon at the levels found in many American homes has a protective effect against lung cancer. Only when the air concentration of radon exceeds the levels shown is there an opposite effect.
Figure 2 summarizes studies of leukemia incidence in 95,000 workers in British nuclear weapons plants between 1955 and 1988. Both the total cancer mortality and the leukemia mortality decreased inversely with increase in radiation exposure. The higher the amount of radiation to which the workers were exposed, the lower the cancer rate. Optimum for protection by radiation from death due to all cancers was at a lifetime dose of at least 20 cSv, while the lifetime optimum for protection from death by leukemia was between 10 and 30 cSv.
In these 95,000 nuclear workers, those who received sufficient doses of radiation had much less cancer than those who were exposed to less radiation. Of course, had the radiation level risen too high, this effect would have disappeared, and, at sufficiently high radiation levels, cancer incidence would have been increased.
Radiation, Science, and Health, Inc., has compiled a substantial number of such studies, which all lead to the same conclusion that low-level radiation decreases cancer, lengthens life, and enhances health.
The most sensible use of low-level radioactive waste is as a concrete and insulation additive in residential homes - especially in areas where there is insufficient natural radiation for optimum health.