RETROSPECTIVE ANALYSIS OF CANCER MORTALITY RATE IN THE POPULATION EXPOSED TO ACCIDENTS AT MAYAK PRODUCTION

Radioactive pollution of the territory of the Chelyabinsk district is significantly determined by accidents happened at the largest nuclear industry enterprise - Mayak Production Association related to the waste disposal of radioactive fluids into the Techa River due to the accident of 1957 and the spread of the dusty radioactive clay from the Karachay lake with the wind. We executed a selective retrospective epidemiologic study of the mortality rate in the population residing in five districts (Argayashsky, Kaslinsky, Krasnoarmeysky, Kunashaksky, Sosnovsky), and two cities - Kasli and Kyshtym (all of them are located in the Chelyabinsk region), exposed to atmospheric and liquid radioactive wastes. In the administrative districts, those were inhabited only in settlements located within the zone of the intensive radioactive pollution were studied. The source of information about the cases of death was the official death records provided by the Office of Vital Records of the Chelyabinsk region for the time period of 1947-1996. As a whole about 135 thousand death records were considered. The gain in the cancer mortality rate was noted for both males and females in cities of Kyshtym and Kasli. In 1950-60s the highest mortality rate indices were typical for the population of Kasli, and in 1960-70-s - for Kyshtym. A two-fold gain in the cancer mortality rate was noted in districts of Chelyabinsk region suffered from the accidents. Practically the permanent excess of estimated benchmarks was noted in Argayashsky and Kaslinski districts and during some periods in Krasnoarmeisky and Sosnovsky districts. In the city of Kasli, Kaslinsky, Argayashsky and Krasnoarmeisky districts the rise in the mortality rate was noted already from the beginning of 1950s and was twice or more as much. The increase in the cancer mortality rate among the population of both genders is sufficiently determined by the growth of age coefficients (in ages of 60-69 and 70 years and older). The coefficient of the cancer mortality rate decreases progressively to the distance from Mayak Production Association.