RADIOACTIVELY CONTAMINATED TERRITORIES OF CHERNIHIVSKA OBLAST OF UKRAINE: THE RADIATION-ECOLOGICAL AND MEDICAL-DEMOGRAPHIC PAST AND PRESENT.

Objective: to determine the current radiationecological and medicaldemographic parameters of the territories of Chernihivska oblast of Ukraine, which were recognized as radioactively contaminated as a result of the Chornobyl Nuclear Power Plant accident, and to assess their changes in the postaccident period.

Objects and methods: The parameters of contamination of natural environments (soil, food products), both with number, structure, natural and migratory movement of population of radioactively contaminated territories of Chernihivska oblast of Ukraine (Kozeletskyi, Koriukivskyi, NovhorodSiverskyi, Ripkynskyi, Semenivskyi, Sosnytskyi, and Chernihivskyi districts) were the study objects.

Materials and methods: Data from the Chernihiv Regional Office of the State Statistics Service of Ukraine,Department of Ecology and Natural Resources of the Chernihiv Regional State Administration, and CentralEnvironmental Dosimetry Register of the State Institution «National Research Center for Radiation Medicine of the National Academy of Medical Sciences of Ukraine» were used. General scientific, mathematicalstatistical, graphic, cartographic, and softwaretechnological research methods are applied.

Results and conclusions: After the accident at the Chornobyl Nuclear Power Plant the largescale radioecological monitoring was conducted on the territory of Chernihivska oblast, where a significant improvement in the state of radioactively contaminated areas had been observed. The number of settlements where the soil contamination density with cesium isotopes exceeded the lower limit for the zone of guaranteed voluntary resettlement (185 kBq*m2) has decreased from 8 to 1. The average regional concentration of 137Cs in milk mostly did not exceed 50 Bq*l1. The average concentration of 137Cs in potatoes from private households over the entire observation period was 5-10 times lower than in milk. Analysis of medical and demographic data allowed concluding that the districts of Chernihivska oblast, which were most intensively contaminated after the Chornobyl accident, feature now some regional problems. There are trends towards population decline and birth rate decrease along with increase in mortality. The most intensive changes had occurred in Kozeletskyi and Ripkynskyi districts, where destructive processes in the age structure of population and a stable trend of increase of mortality rates were revealed. Research should be continued.