Modern radiation cytogenetics had accepted long ago a postulate that DNA molecules as the essential biological substrate represent the most important target of the ionising radiation. The effects of the radiation include possible development of highly delicate lesions of the genetic material which may be manifested as structural chromosomal aberrations. The study represents the results of years - long cytogenetic studies of chromosomal aberrations in individuals occupationally exposed to ionising irradiation (684 subjects). The subjects were classified into different groups according to the type of their jobs. During the period 1995-1996. the incidence of chromosomal aberrations was increased among nuclear medicine professionals ranging from 19,1-10,9%. Significant increase of chromosomal aberration incidence was evidenced during the period 1997-1998. among radiologists and X-ray technicians, ranging from 23.52% to 19.64%. Dicentric type of chromosomal aberrations, ring - shaped chromosomes and acentric fragments were detected. Occupational exposure is particularly delicate issue due to the chronic exposure to small doses of ionising irradiation and consequential cumulative irradiation effect necessitating the insight into the biological response of the organism to the given conditions of exposure. Adequate education of the staff and appropriate protection against irradiation, which is at the same time best prevention both for early disorders and late consequences of the ionising irradiation.
