Localization of breakpoints in the karyotype of workers professionally exposed to benzene.

Cytogenetic analysis was carried out on peripheral blood lymphocytes of 33 workers professionally exposed to benzene for 10-26 years. In the examined group structural chromosome aberrations were found in 147 metaphases (4.7%). Statistical analysis has shown that the distribution of breakpoints was not random. Chromosomes 2, 4 and 9 are almost twice as susceptible to breaks, while chromosomes 1 and 2 are almost twice as susceptible to gaps, as would be expected based on a random distribution of damage among chromosomes.