Purpose: To estimate the translocation-induction rate under chronic exposur
e conditions by measuring chromosome aberration frequencies in lymphocytes
from Mayak nuclear workers using fluorescence in situ hybridization (FISH).
Materials and methods: Lymphocytes were examined from 27 nuclear workers at
the Mayak Production Association and two control individuals using FISH wi
th probes for chromosomes 1, 2 and 4. Official doses derived from worker fi
lm-badge records varied from 0 to 8.50 Gy.
Results: The mean (+/- SD) genome-equivalent translocation frequency (F-G)
was 2.30 (+/-0.75)% in the zero-dose group (n=7), and Poisson regression an
alysis provided the best-fit equation of F-G(%)=2.96 (+/-0.39) +0.69 (+/-0.
14)D+0.12(+/-0.05)A, where D is the film-badge-derived dose (Gy), and A is
age centred at 67 years. The induction rate would increase to nearly 1% Gy(
-1) if the radiation dose to bone marrow, one of the major organs for lymph
ocytes and where their precursor cells reside, is considered.
Conclusion: The estimated induction rate in vivo appeared substantially sma
ller than linear coefficients estimated from various in vitro studies.