Study of genetic effects in somatic cells of children living on the contaminated territories in Belarus

The general conclusion of our study is the seriousness of discovered genetic disturbances in the examined children in Bragin town and other settlements in the Bragin district of the Gomel region. The results of seven-year monitoring of children with use of in vivo micronucleus analysis of lymphocytes have shown that the highest level of mutation was found in the children born before the Chernobyl catastrophe. Consequently, the principle of radiation protection according to the level of average annual radiation dose is not acceptable to protect the children in the Bragin district because it does not take into account the total radiation dose since 1986 which conditions the radiation consequences for children health. The analysis of the results of 1988-1994 indicates that, under the chronic action of ionizing radiation, complicated interactions between mutation pressure and selective process against cells with genetic injuries have been taking place in lymphocyte populations of the children in the Bragin district. Substantial differences between the examined children and the control were found in the level of mutations registered n peripheral blood lymphocytes both in vivo and ex vivo. The micronuclei level in lymphocyte populations in vivo did not decrease during 1988-1994. On the contrary , it increased approximately one order, whereas one mitotic division ex vivo in cell culture indicated substantial changes in different trends. The cells with gene mutations capable to continue their life activity, apparently, undergo the selection in minus-trend to some extent but, probably, also contribute to the plus-trend selection both in vivo and ex vivo. As a result, in the last years we observe in ex vivo examination the high level of gene mutations against the background of relatively low level of chromosomal injuries. (J.P.N.)