Effect of tritium on embryo and fetuses in rodents

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In carcinogenesis study of HTO in mice, 3.6m Gy/day induced life-shortening, but no evidence was observed on the incidence of tumor development, hormetic sign, life shortening under the more lower HTO concentrations. By a combined treatment of HTO and MNU in female SD rats, there were no increase of mammary tumors in HTO treated group, but significant increase of tumor development was observed by HTO.To identify the relative biological effectiveness of HTO,stem cell assay of intestinal crypt was done and 60 m Ci/mouse HTO did not kill the BCF_1 mice, which is rather high value compare to the previous report. Tritium gas did not influence too much to the newborn babies, but it gave twice as much as of damage to the latter half of fetuses compared to the former half of fetuses. In embryonic fetuses, the damage caused by HTO seemed to be unique, but its characterisric are under investigation by Hamster's embryo. Influence on the brain development is just started in this group, and its main observation is to analyze eye-opening, running and changes of neuropeptides. By the dose of 5 c Gy of HTO,it induces synony-mous signs to the dose of 20 cGy of gamma ray. By pre-treatment of 5 cGy of HTO,leukemiccells in vitro exposed to various doses of gamma-ray showed decreased mutation brequency. In human leukemic cell lines, Fish technique was introduced to identify the definite markers caused by gamma-rays. By this method, 14 day of myeloid cells or 40 days of lymphoid cells were identified of respective new markers.Ingeno mice receiving lac Z genes are under development and establishment and introduction to our experiment should open new avenue.