The Follow-up Study of Chromosomal aberrations in Chernobyl Clean-up Workers

A cytogenetic study was carried out on 359 clean-up workers who worked at the Chernobyl station in 1986-1989. The investigation was performed 6-12 years after irradiation. Chromosome type damages, i.e. double fragments, dicentrics and rings were significantly increased in the cleanup workers compared to the control. Chromatid exchanges were found only in the clean-up workers. A temporal change of radiation makers was also investigated based on the data of 243 persons who worked at Chernobyl in 1986. The temporal variation of dicentric frequency shows an inexplicable tendency towards the increase of dicentrics rate for the period of 8-12 years after irradiation. The association between the frequency of different types of chromosomal aberrations and such variables as smoking habits, coffee, tea, alcohol consumption, etc. was also analysed using a stepwise multiple regression analysis. A statistically significant association was only observed between smoking and chromatid exchanges. This type of aberrations was significantly higher in the smoking subgroup than in the non-smoking subgroup of the clean-up workers. The fact of an increased level of unstable chromosomal aberrations in a remote period after irradiation allows us to suppose that other pathways of genomic burden may exist in addition to straight radiation action at the time of irradiation. Introduction Chromosome damage induced in human lymphocytes is often considered a sensitive indicator of radiation exposure [1-3]. An increased level of structural chromosomal aberrations in the clean-up workers soon after the Chernobyl accident has been reported [4,5]. It is known that the frequency of radiation markers (dicentric and ring chromosomes) decreases in time [6,7]. So, it is expected that the frequency of chromosomal aberrations (CA) in the clean-up workers, who suffered from low doses of radiation, would become as low as the control level some years after the accident. However, increased rate of chromosomal aberrations in the clean-up workers was demonstrated 4-6 years after the Chernobyl accident [8-11]. A follow-up study of Chernobyl clean-up workers has been carried out at All-Russian Centre of Emergency and Radiation Medicine Emercom of Russia (ARCERM) since 1992 in order to assess the consequences of low doses of ionising radiation on their health. Cytogenetical investigation was carried out simultaneously with clinical examination. The goal of this paper is to present the results of the follow-up study of cytogenetical damage in the peripheral blood lymphocytes from the clean-up workers in a remote period (6-12 years) after the Chernobyl accident. Materials and methods A cytogenetic study was carried out on 359 clean-up workers who worked at the Chernobyl station in 1986-1989. The investigation was performed 6-12 years after irradiation. 281 persons had official dose of irradiation, estimated by dosimetric service at Chernobyl. Most of them received up to 25 cGy, but 30 persons received from 25.1 cGy to 100 cGy. Thus, the mean dose of irradiation for clean-up workers who