tions. In general, the evidence to date indicates that the more exposure 

 the human race as a whole receives, the more it will be damaged. The 

 questions of how much is too much, and what is a permissible dose, are 

 patently unanswerable in the light of present knowledge. The problem 

 is somewhat like that pertaining to the use of antibiotics — indiscriminate 

 use is indefensible, but where there is a choice between two evils one 

 is expected to choose the lesser. In most cases this is more a matter of 

 ethics than of science. 



^ 400 



^ / ^< / / / / / / / y ^' ^' 



STAGE IRRADIATED 



Figure 9-4. Graph Showing the Number of Chromosome Fragments In- 

 duced by 50 r of X Rays at Various Stages of Meiosis in Trillium erectiim. 

 (From Sparrow, A. H., 1951. "Radiation Sensitivity of Cells During Mitotic 

 and Meiotic Cycles with Emphasis on Possible Cytochemical Changes," Ann. 

 N. Y. Acad. Sci., 51, Fig. 2, p. 1513.) 



BIBLIOGRAPHY 



Altenberg, E., 1928. "The Limit of Radiation Frequency Effective in Pro- 

 ducing Mutations," Am. Naturalist, 62, 540-545. 



Blum, H. F.. 1959. "Environmental Radiation and Cancer," Science, 130, 

 1545-1547. 



Errera, M., 1959. "Effects of Radiations on Cells," /// "The Cell," J. Brachet 

 and A. E. Mirsky (Eds.), Vol. 1, Academic Press, New York, N.Y., 

 pp. 695-740. 



Kihlman, B. A., 1956. "Factors Affecting the Production of Chromosome 

 Aberrations by Chemicals." /. Biophys. Biochem. Cytol., 2, 543-555. 



200 / CHAPTER 9 



