249 Cell nucleus seeking OBT: a still neglected problem? 4. Some people point to the fact that most of the results obtained up to now for the early stages of pregnancy are related to the death of the preimplantation embryo and that this is not “much of a concern”, because this effect, if it occurs, will be undetectable in real life. Besides the rather questionable ethical position, it is also premature to conclude that embryonic death is the only effect to be expected. Almost all of the studies have only looked at this effect, because this is methodologically the easiest way to run the experiments. This does not mean that other effects (malformations, solid tumours, leukaemia) are not to be expected. And at least for malformations, a threshold dose could not be detected after X-ray exposure in 1-cell embryos of those mouse strains that react with malformations after exposure of this stage (Müller et al., 1994) 4 A final remark This overviewdoes not “prove” that cell nucleus seekingOBTs present an extraordinarily high hazard in the environment. But those compounds are clearly more dangerous than HTO or HT, and therefore one should be sure that the risk is acceptable or, even better, non-existent, before one releases high amounts of tritium into the environment. REFERENCES Balonov M.I., Muksinova K.N., Mushkacheva G.S. (1993) Tritium radiobiological effects in mammals: review of experiments of the last decade in Russia, Health Physics 65, 713-726. Bond V.P., Feinendegen L.E. (1966) Intranuclear 3H thymidine: Dosimetric, radiobiological and radiation protection aspects, Health Physics 12, 1007-1020. Clerici L., Carroll M.J., Merlini M., Vercellini L., Campagnari F. (1984) The toxicity of tritium: the effects of tritiated amino-acids on preimplanted mouse embryos, International Journal of Radiation Biology 45, 245-250. Diabate S., Strack S. (1993) Organically bound tritium, Health Physics 65, 698-712. Horner D., McLaren A. (1974) The effect of low concentrations of [3H]-thymidine on pre- and postimplantation mouse embryos, Biology of Reproduction11, 553-557. Kelly S.J., Rossant J. (1976) The effect of short-term labelling in [3H] thymidine on the viability of mouse blastomeres: alone and in combination with unlabelled blastomeres, Journal of Embryology and Experimental Morphology35, 95-106. Killen H.M., Carroll J. (1989) The effects of tritium on embryo development: the embryotoxic effects of [3H]tryptophan, International Journal of Radiation Biology56, 139-149. Matsuda Y., Yamada T., Tobari I. (1986) Chromosome aberrations induced by tritiated water or 60Co gamma-rays at early pronuclear stage in mouse eggs, Mutation Research160, 87-93. Müller W.-U., Heckeley N., Streffer C. (1996) Effects of cell cycle specific exposure to ³H-thymidine or ³H-arginine on development and cell proliferation of mouse embryos, Radiation and Environmental Biophysics 35, 267-271. Müller W.-U., Spindle A. (1986) Induction of sister chromatid exchange in preimplantation mouse embryos in vitro by 3H-thymidine or ultraviolet light in combination with caffeine, Teratogenesis, Carcinogenesis, and Mutagenesis 6, 107-114. 4. Quelques uns insistent sur le fait que la plupart des résultats obtenus jusqu’à présent pour les premiers stades de la grossesse ont un rapport avec la mort de l’embryon avant implantation et que ce n’est pas “d’un grand intérêt”, parce que cet effet, s’il a lieu, ne sera pas détectable dans la vie réelle. Mis à part la position éthique plutôt questionnable, il est aussi prématuré de conclure que la mort de l’embryon est le seul effet attendu. Presque toutes les études ont seulement examiné cet effet, parce que c’est sur le plan méthodologique la façon la plus simple de conduire l’expérience. Cela ne signifie pas que d’autres effets (malformations, tumeurs massives, leucémies) ne sont pas à être attendus. Et au moins pour les malformations, une dose seuil ne pouvait pas être détectée après une exposition aux rayons X d’embryons monocellulaires de ces lignées de souris, qui réagissent par des malformations après une exposition à ce stade (Müller et al., 1994). 4 Une remarque finale Cette revue ne “prouve” pas que les molécules marquées au tritium recherchées par le noyau de la cellule représentent un danger élevé extraordinaire dans l’environnement.Mais cesmolécules sont clairement plus dangereuses que HTO ou HT, et par conséquent on devrait être sûr que le risque est acceptable ou, encore mieux, inexistant, avant de libérer des niveaux élevés de tritium dans l’environnement. RÉFÉRENCES BIBLIOGRAPHIQUES Balonov M.I., Muksinova K.N., Mushkacheva G.S. (1993) Tritium radiobiological effects in mammals: review of experiments of the last decade in Russia, Health Physics 65, 713-726. Bond V.P., Feinendegen L.E. (1966) Intranuclear 3H thymidine: Dosimetric, radiobiological and radiation protection aspects, Health Physics 12, 1007-1020. Clerici L., Carroll M.J., Merlini M., Vercellini L., Campagnari F. (1984) The toxicity of tritium: the effects of tritiated amino-acids on preimplanted mouse embryos, International Journal of Radiation Biology 45, 245-250. Diabate S., Strack S. (1993) Organically bound tritium, Health Physics 65, 698-712. Horner D., McLaren A. (1974) The effect of low concentrations of [3H]-thymidine on pre- and postimplantation mouse embryos, Biology of Reproduction11, 553-557. Kelly S.J., Rossant J. (1976) The effect of short-term labelling in [3H] thymidine on the viability of mouse blastomeres: alone and in combination with unlabelled blastomeres, Journal of Embryology and Experimental Morphology35, 95-106. Killen H.M., Carroll J. (1989) The effects of tritium on embryo development: the embryotoxic effects of [3H]tryptophan, International Journal of Radiation Biology56, 139-149. Matsuda Y., Yamada T., Tobari I. (1986) Chromosome aberrations induced by tritiated water or 60Co gamma-rays at early pronuclear stage in mouse eggs, Mutation Research160, 87-93. Müller W.-U., Heckeley N., Streffer C. (1996) Effects of cell cycle specific exposure to ³H-thymidine or ³H-arginine on development and cell proliferation of mouse embryos, Radiation and Environmental Biophysics 35, 267-271. Müller W.-U., Spindle A. (1986) Induction of sister chromatid exchange in preimplantation mouse embryos in vitro by 3H-thymidine or ultraviolet light in combination with caffeine, Teratogenesis, Carcinogenesis, and Mutagenesis 6, 107-114.
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