Seventeen-year follow-up study on chromosomal aberrations in five victims accidentally exposed to several Gy of 60Co gamma-rays.
On 25 June 1990, a radiation accident occurred in a (60)Co source radiation unit in Shanghai, due to violations in operation regulations. This accident resulted in the exposure of seven individuals to acute high-dose and dose-rate whole-body external irradiation. Conventional chromosomal aberration analysis, G-banding automatic karyotype analysis and/or fluorescent in situ hybridization (FISH) painting methods were used to analyze chromosomal aberrations in peripheral blood lymphocytes from five of the victims 24 h to 17 years after accidental exposure to 1.9-5.1 Gy of (60)Co gamma-rays. The frequency of unstable chromosomal aberrations (dicentrics and rings) remained at constant levels 1 month after exposure. Three months after exposure, the frequency was reduced by 20-40% in three victims, while no reduction was seen in the other two victims. Twelve years after exposure, the number of dicentrics and rings decreased by more than 90%, and did not reveal a dose-dependent relationship. However, even at 12-17 years after exposure, stable chromosome aberrations, dominated by translocations, remained at a high level in a dose-dependent manner. The frequency of stable chromosomal aberrations detected by FISH showed a similar dose-dependent relationship as that detected by karyotype analysis of G-banding chromosomes. The G-banding analysis also suggested that the pattern of chromosome breakpoints is random. The FISH data showed a decreasing tendency with time for chromosome translocation frequency in the peripheral lymphocytes, and the rate of reduction varied among different individuals. It is likely that the higher dose the victim received, the lesser the translocation frequency decreased with time. The G-banding data also showed that the rate of reduction of translocations is different among individuals. From 5 to 17 years after accidental irradiation, a very small reduction (approximately 10%) of translocation frequency was observed in victims C and D, while there was about a 35% reduction (the highest among the victims) for victim G who received the smallest dose (1.9 Gy). These observations can be used to validate the existence of chromosomal aberrations in peripheral blood lymphocytes as a biological dosimeter for radiation exposures.
Chen
Ying
Y
Department of Radiation Toxicology and Oncology, Beijing Institute of Radiation Medicine, 27 Taiping Road, 100850, Beijing, People's Republic of China. yingchen29@yahoo.com.cn
Jin
Cui-Zhen
CZ
Zhang
Xue-Qing
XQ
Ge
Shi-Li
SL
Zhang
Ze-Yun
ZY
Xu
Hui
H
Liu
Xiu-Lin
XL
Wu
De-Chang
DC
Zhou
Ping-Kun
PK
D000062:Accidents, Occupational; D000328:Adult; D002869:Chromosome Aberrations / Q000528:radiation effects*; D002871:Chromosome Banding; D003037:Cobalt Radioisotopes / Q000009:adverse effects; D015342:DNA Probes / Q000378:metabolism; D005500:Follow-Up Studies; D005720:Gamma Rays / Q000009:adverse effects; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D008297:Male; D008875:Middle Aged; D016273:Occupational Exposure; D011829:Radiation Dosage; D013997:Time Factors; D014178:Translocation, Genetic / Q000528:radiation effects
D003037:Cobalt Radioisotopes; D015342:DNA Probes