CHROMOSOME TRANSLOCATIONS IN LYMPHOCYTES FROM INDIVIDUALS EXPOSED TO ~(137)Cs 7.5 YEARS AFTER THE ACCIDENT IN GOIANIA (BRAZIL)

摘要

A cytogenetic study was carrried out for 12 individuals 7.5 y after exposure to ~(137)Cs in Goiania (Brazil). The fre- quencies of translocations were determined by the fluorescence in situ hybridisation (FISH) method, using two cocktails of chromosome probes: #1, 6, 11 and #3, 4, 8, and ranges of 0.5 to 9.7 and zero to 4.2 translocations per 100 cells were found, respectively. The mean genomic translocation frequencies were 5.15 +- 1.11, 8.84 +- 1.63 and 22.58 translocations/100 cells for different levels of absorbed doses: <1.0, 1.5-2.0 and 4.6 Gy, respectively, indicating a 10-45 fold increase in relation to the normal frequency. For seven probands, the frequencies of dicentrics were 10 times higher than the control value. The present results are also relevant to a discussion of the reliability and limitations of the analysis of translocations (for a limited number of chromosomes) as a parameter for retrospective biological dosimetry, in cases of human exposure to ionising radiation.