Telomeric associations in cigarette smokers exposed to low levels of X-rays

Telomeric association (TA), i.e. fusion of chromosomes by their telomeres, predisposes a cell to genetic instability. Because of this we investigated the effect of X-rays exposure and cigarette smoking on the frequency of TA in peripheral blood lymphocytes of exposed individuals, in order to determi ne if TA can be a chromosomal marker in populations exposed to these carcin ogens and if there is an synergistic effect between both agents. We found t hat the exposed groups show a greater percentage of TA when compared with t he control group (P < 0.001). However, although the percentage of metaphase s with TA in the group with combined exposure (12.6%) was greater than in t he others exposed groups (P < 0.05), this value was less than the sum of th e two individual effects (15.1%). Our results suggest that probably there i s not an additive or synergistic effect between X-rays and smoking, and tha t TA may be a useful cytogenetic marker for evaluating populations exposed to mutagens. (C) 2001 published by Elsevier Science B.V.