The purpose of this paper is to establish the cytogenetic analyses of human peripheral blood samples caused by simulation of partial-body exposures. Either accidental or occupational partial-body exposure to ionizing radiation poses significant health hazards that are indicated by induction of chromosome aberrations (CA). The percentages of mixtures of blood samples irradiated in vitro with 2 Gy of gamma rays were 10, 25, 50, 75 and 100.0%. Lymphocytes were cultured for 48 hr, harvested with standard procedures and then first-division metaphase cells were analyzed. It showed that the frequencies of unstable CA depend on the proportion of the irradiated blood. All frequencies of the observed CA was lower than that of predicted or calculated from 100% exposed blood, except in one case, indicating a phenomenon of “dilution” of the un-irradiated into irradiated lymphocytes that may take place a bystander effects. Our data showed that the quantification of CA in human peripheral blood lymphocytes may be an important tool of dose assessment for partial-body exposure to ionizing radiation.

Key words: Biological dosimetry, Human peripheral lymphocyte, Partial-body irradiation, Unstable chromosome aberrations