United Kingdom (Continued) together with very pertinent analyses of the data, the problem of genetic disability and its relation to radiation effects. G/R.105 LEUKEMIA AND APLASTIC ANEMIA IN PATIENTS IRRADIATED FOR ANKYLOSING SPONDYLITIS The incidence of leukemia and of aplastic anemia was investigated in patients treated in Britain for ankylosing spondylitis by means of ionizing radiations during the years 1935-1954. Relationship between radiation dose and incidence of leukemia was evaluated. The answers suggest the adoption of working hypothesis that for low doses the incidence of leukemia bears a simple proportional relationship to the doseof radiation, and that there is no threshold dose for the induction of the disease. The dose to the whole bone marrow which would have doubled the expected incidence of leukemia may lie within 30 to 50 r for irradiation with X-rays. G/R.114 THE RELATIVE HAZARDS OF STRONTIUM-90 AND RADIUM-226 Methodsfor calculations of the doses received by soft tissue cavities in bone containing Sr™ and Ra?” are presented. Non-uniformity factors are given for the dose from Sr™. Calculation of the maximum permissible body burden for radium on the basis of a given maximum permissible dose-rate to bone gives a wide range of values, depending on the assumptions made. In the case of radio- strontium, the range of possible values is less. It is suggested that radium be no longer taken as the basis for the calculation of maximum permissible body burden of Sr*. G/R.115 SHORTENING OF LIFE BY CHRONIC IRRADIATION: THE EXPERIMENTAL FACTS A survey of all published experimental results relating to shortening of lifespan of mice due to chronic irradiation. The comparison of effects between gamma-rays of Co™ and fast neutrons is made; the R.B.E. factor used for fast neutrons was 13. A good agreement of experimental results has been found indicating that chronic irradiation both with gamma-rays and neutrons shortensthe life of mice in a reproducible manner. Nostatistically significant data were found below the weekly dose of 10 r. The possibility of extrapolation and the possible dose-effect relationship is discussed. G/R.126 RADIOSTRONTIUMIN SOIL, GRASS, MILK, AND BONEIN U. K. 1956 RESULTS Results of Sr® analysis of soil, grass, and animal bone for 12 stations in U. K. are given. Human bone specimens obtained in 1956 have also been measured. G/R.128 IONIZING RADIATION AND THE SOCIALLY HANDICAPPED Collects available data and calculations concerning the numbers in various classes of handicapped individuals in the U. K. and the relationships of these numbers to genetic factors, mutation rates, and radiation levels. G/R.132 THE DETERMINATION OF LONG-LIVED FALLOUT IN RAIN WATER A method is described for the determination of long-lived isotopes in samples of rain water. Some attention is paid to the development of the method, including details of the checks to ensure radiochemical purity of the final sources used for counting. THE WORLD-WIDE DEPOSITION OF LONG-LIVED FISSION PRODUCTS FROM NUCLEAR TEST EXPLOSIONS A network of 6 stations in the U.K. and 13 other parts of the world has been set up for rain water collection. Samples are analyzed for Sr®*, sr®°, Cs!37, and Ce’4, This report contains an account of the results obtained so far, and some discussion of the present and future levels of Sr® in U.K. soil. 196 a G/R.143