Effects of Radiation on Pituitary Cancer Mortality

In 1979, R.L. Ullrich et al. compared the pituitary cancer mortality rate of 400 female mice exposed to single doses of 10, 25, 50 and 100 cGy. [Ullrich, R.L. et al. Influence of radiation on the development of neoplastic disease in mice. Radiation Research, 80, 135, 1979.]

The normal mortality from this cancer in the control mice was 6.6% - a value that was set as the 100% or control level on Figure 8.

Caption for Figure 8: Pituitary Cancer in Mice: Source: Ullrich, R.L. and Storer, J.B., Influence of radiation on the development of neoplastic disease in mice. Radiation Research, 80, 135, 1979. (For similar studies by Ullrich et al., see also Radiation Research, 68, 115, 1976, and several other case studies in this chapter.)

As shown, pituitary cancer mortality was decreased nearly 20% at an exposure of 25 cGy, which was similar to results for ovarian cancer (20% decrease), mammary cancer (46% decrease), and uterine cancer (13% decrease). Needless to say, these are not the kind (or even the direction) of results predicted by the LNT.

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.