Effects of Radiation on Living Organisms Early and Late Effects of Radiation of Different Project Title: Qualityand at Different Dose Rate 16, Technical Progress in FY 1973: (Cont'd.) RX-03-O1-(a) These results are reported in the 189 documents from the Biology Department. The theory group has continued to extend and refine the theory of dual radiation accion ( A. M. Kellerer and H. H. Rossi). These results are reported in the annual reports of the Radiological Research Laboratory, Columbia University. 17. Expected Results in FY 1974: The completion of all planned beam lines at RARAF will permit research to proceed more efficiently so that a larger number and greater variety of research projects can be undertaken. The international intercomparison of neutron dosimetry will consist of measurements made at RARAF by a‘dozen teams of scientists at various intervals during the year. Pending approval by the AEC of a recent proposal by the BNL Health Physics Division, supplementary equipment and staff will be acquired to establish at RARAF a neutron calibration facility to provide outside and Local users with standard, well-defined neutron fluences suitable for calibration and testing of radiation instruments and personnel monitoring devices. Radiological physics studies are in progress in preparation for two new radiobiclogy experiments. The first will utilize a molecular hydrogen beam to study the biological significance of energy depositions ‘at the nanometer level. The * ‘ second involves the use of a microbeam to irradiate single cells with one or a known number of charged particles. Radiobiology experiments will be continued involving neutron energy dependence dose rate dependence and OER for irradiations & Tradescantia inflorescences and Chinese hamster lung cells. The studies on the induction of mammary neoplasms in rats will also be continued. The Drosophila and Vicia faba experiments have been terminated and the data are being (Bond, Rossi) analyzed. Data will be forthcoming from the Sprague-Dawley rats exposed to neutron doses ranging from 0,125 through 8 rads so that preliminary conclusions can be reached in regard to RBE values for neutron rat mammary carcinogenesis. The August-Copenhagen hybrid rat has been reported to show Spra synergistic interaction of neutron radiation and exogenous fi administration. Lewis rats given either x radiation or DMBA nearing the end of their life span so that any differences between ley rats and Lewis rats can be documented in preparation for studies on possible hormonal differences in the two strains. Certain antioxidants, widely used in food and commerce, have been claimed to reduce the rat mammary neoplastic response to chemical carcinogens; some antioxidants will be studied in regard to their influence on chemical carcinogenesis and (See Continuation Sheet) b4192b4 RX-171