Evaluation of the frequencies of chromosomal aberrations in a population exposed to prolonged low dose-rate 60Co gamma-irradiation.
OBJECTIVE
Chromosomal aberration analysis in peripheral blood lymphocytes was performed to evaluate late cytogenetic effects of long-term low dose-rate gamma-irradiation exposure among students and residents exposed in radiocontaminated buildings.


METHODS
Blood samples were taken from 1913 subjects (age 17.8+/-13.6, mean+/-SD) 5-8 years after their relocation from radioactive environments as well as from 176 non-exposed subjects (age 29.6+/-11.9) from the local community. Their lymphocytes were cultured for 48 h and metaphase spreads were prepared. A total of 208 900 metaphases were analysed for different types of chromosomal aberrations.


RESULTS
Relatively higher frequencies of translocations (2.1 x 10(-3)), rings (0.6 x 10(-3)) and dicentrics (0.6 x 10(-3)) were noted in the exposed population as compared with the nonexposed reference populations. Moreover, 356 (78.6%) of the 453 inversions were found on 14q11.2q32 in the exposed population. Among 392 well-demonstrated translocations, 167 (42.6%) and 175 (44.6%) occurred in chromosomes 7 and 14, respectively, while 139 (35.5%) occurred as t(7;14). In particular, the aberrations t(7;14)(p13;q11.2), t(7;14)(p15;q11.2) and t(7;14)(q36;q11.2) were the most prevalent, occurring with frequencies of 19 (13.7%), 20 (14.4%) and 27 (19.4%), respectively. In these, 3205 breakpoints were documented, with chromosomes 7, 9 and 14 shown to carry significantly higher frequencies of breakpoints than expected (chi(2)-test, p<0.0001). A further six hotspots were identified on 7p15 (57, 1.8%), 7q36 (42, 1.3%), 9q12 (244, 7.6%), 9q13 (86, 2.7%), 14q11.2 (509, 15.9%) and 14q32 (387, 12.1%) in the exposed population.


CONCLUSIONS
In comparison with the unexposed population, we observed increased frequencies of various chromosomal aberrations in this human population with previous exposure to prolonged low dose-rate gamma-radiation. Moreover, several hotspot breakpoints and inversions and translocations were observed on chromosomes 7 and 14.
Hsieh
Wanhua A
WA
Institute of Environmental Health Sciences & Institute of Public Health, National Yangming University Medical School, 155, Section 2, Linon Street, Taipei, Taiwan 112.
Ni
Chyiyao
C
Hwang
Jeng-Jong
JJ
Fang
Jye-Siung
JS
Lin
Shuan-Pei
SP
Lin
Yiping A
YA
Huang
T W
TW
Chang
Wushou P
WP
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D002869:Chromosome Aberrations; D003037:Cobalt Radioisotopes / Q000009:adverse effects*; D005260:Female; D005720:Gamma Rays / Q000009:adverse effects*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged
D003037:Cobalt Radioisotopes