The morbidity with leukoses and other hemoblastoses in 6 south-west districts of Bryansk oblast (territory of observation), the remaining 21 districts (territory of comparison) and Bryansk was compared. In the post-accidental period a positive trend of morbidity in the oblast as to acute leukoses and non-Hodgkin' diseases was determined. The relative risk of morbidity on the territory of observation does not deviate from 1,0 and exceeds 1,0 in Bryansk. The morbidity indices of acute leukoses and non-Hodgkin' diseases among children are the most high for Bryansk 3,79 and 1,90, respectively; for the territory of comparison 3,31 and 1,42; for the territory of observation 3,41 and 1,28. In 1986 on the territory of observation the excess of morbidity with acute leukoses (7 cases), with morbidity index of 11,95 (95% confidence interval within the limits of 5-25) was registered. The relative risk amounted to 6,13, p=0,07. In two children a diagnosis was determined before the Chernobyl accident, two children were taken ill in June, two in July and one in August. During the following 7 years the relative risk for all analyzing forms did not exceed 1,0. The Puasson probability of stochastic aggregation over 1 year (7 cases of acute leukoses) comprises 0,001. A special feature of this event was an unusual distribution of sick children on age 6 from 7 are boys. A descriptive epidemiological analysis gives no way of judging the nature of event, at the same time it is beyond reason to associate it with radiation effect. Analysis of morbidity is insufficient for determination of causal relationship between risk of arising acute leukoses and radiation effect due to the ChNPP accident.

Beginning from 1986, at Hematological Research Centre (HRC) epidemiological monitoring has been performed on hemoblastoses in Bryansky district, which suffered from the Chernobyl accident more than any other area of Russia. The collection of personal information is organized about each case of disease from all possible sources, diagnosis verification, computer control, storage and analysis of materials. A specialized Register of Blood diseases is created, including demographical and ecological files. Retrospective period of monitoring 1979-1985, afteraccident period-from 1986. In the register 2832 cases were accumulated of hemoblastoses up to 1993. Regions are selected for monitoring with high levels of contamination by 137Cs (15 Ci/sq.km and more), and area for comparison--the other 21 regions of the district. The comparison did not reveal substantial differences. Further epidemiological analysis must be performed. Taking into account dose loads, special studies are initiated.