CHROMOSOME ABERRATIONS AND OTHER EFFECTS PRODUCED BY SR-90 - Y-90 IN CHINESE HAMSTERS

Chinese hamsters were injected with 0, 0·2, 0·5, 1·0, 2·0, 3·0 and 5·0 μCi of 90Sr-90Y/g body-weight and sacrificed at 2, 14, 28, 56, 113 and 224 days after injection to assess the biological damage. The 3·0 and 5·0 μCi injections produced deaths by 10 days after injection, whereas with 1·0 and 2·0 μCi, most early deaths occurred at 120 to 180 days and 40 to 80 days, respectively. In all cases, death appeared to be related to total accumulated radiation dose and cellular depletion of the bone-marrow. Changes in bone-marrow cells at each time-point included an increase in number of chromosome breaks/cell as a function of dose accumulated at the time of death, and a response of the bone-marrow mitotic index which reflected an increase above control levels with a low total dose and a decrease as the dose passed a critical point. The number of chromatid plus isochromatid deletions increased with increased injected activity and dose-rate, and the relative frequency of chromosome exchanges increased with time. Examples of cellular cloning were noted. © 1969 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted.