Air crew members of international flights are exposed to ionizing radiations originated from the collision of cosmic particles with atoms of the atmosphere. The degree of exposure varies according to the altitude, latitude, and solar activity. The cytogenetical analysis showed a significant increase of dicentric chromosomes (14.5 ± 0.76 per 1,000 cells) in active air crew members as well as in retired air crew members (7.5 ± 0.59 per 1,000 cells) in relation to controls (0.5 ± 0.05 per 1,000 cells). In active members the frequency of ring chromosomes was also increased (2.0 ± 0.31 per 1,000 cells) but not found in retired crew members. These observations suggest a high degree of exposure to ionizing radiations of air crew personnel. Consequently, the cytogenetic follow-up of air crews chronically exposed to low radiation doses is an open field for further investigations.
