On the biological effects of high background radioactivity: studies on Tradescantia grown in radioactive monazite sand

Abstract Tradescantia , clone 02, plants were grown in garden soil and were exposed to low level external radiations ranging from 0·08 mR/hr to 1·3 mR/hr or were raised in radioactive monazite sand cultures. In the experiment on external exposure alone, one group of plants was irradiated from transplanting while another group was irradiated from flowering. The occurrence of somatic mutations in the staminal hairs was recorded from flowering, for a period of over sixty days. After the specified period of growth, the plants from the monazite cultures and control were sacrificed and assayed for the absorbed radionuclides, especially for the alpha emitters. The radionuclide content in the plant body did not show a direct relation with the amount of monazite in the cultures. It appears that the contribution from the absorbed radionuclides is much more important in the production of biological damage than external irradiation alone.