The frequency and spectrum of cytogenetic anomalies in employees of Siberian Group of Chemical Enterprises

: The results of the study of frequency and spectrum of cytogenetic anomalies in 657 healthy employees of the main facilities of the Siberian Group of Chemical Enterprises exposed to external, internal and combined irradiation are presented. No dependence between age and chromosome aberrations frequency was revealed. Chronic external exposure appeared to be the main factor of induction of chromosome aberrations. The frequency of aberrant cells, chromosome type aberrations, paired fragments and rings was statistically significantly higher in employees exposed to external irradiation as compared to persons exposed to combined irradiation. A nonlinear dependence the dose of irradiation and frequency of chromosome aberrations was revealed. A statistically significant decrease of prevalence of aberrant cells, aberration of chromatid and chromosome type was established in employees exposed to irradiation at a dose range of > 0-10 mSv compared to the control group. This agrees with the phenomenon of radiation hormesis. A significant increase of the frequency of chromosome aberrations was not observed at doses below > 40 mSv. In employees exposed to irradiation at a dose range > 40-100 mSv, a statistically significant increase of frequencies of aberrant metaphases, aberrations of chromatid and chromosome types was established. Same was found for dicentrics at dose range of >100-200 mSv. This supports a well known linear threshold model. Dose-effect curve has a plateau at doses ranged from 100 to 500 mSv.