Sister chromatid exchanges (SCE) and structural chromosome aberrations were analyzed in peripheral blood lymphocytes of 100 individuals, and correlated to age and sex. No correlation was found between the frequency of SCE and age, but older individuals had significantly more structural aberrations than younger. Females had significantly more SCE as well as structural chromosome aberrations than males. The positive correlations of SCE and structural aberrations to age and sex were also significant when these factors, as well as smoking habits, were taken into consideration in an analysis of covariance.

Cytogenetic effects of ciprofloxacin (500 to 2,000 mg daily) and ofloxacin (200 mg daily) were studied in lymphocytes from 31 patients treated for 1 to 10 weeks. Blood samples for cytogenetic analysis were taken before the start of treatment from all patients, after 1 week from 25 patients, and after 2, 4, 6, and 10 weeks from six patients. No chromosome-damaging effect could be demonstrated in any treatment group. The mean aberration yields for each cytogenetic parameter studied and the total number of aberrations were all normal at each sampling occasion.Ciprofloxacin, norfloxacin, and ofloxacin are new quinolone derivatives which are structurally related to nalidixic acid but far more bactericidal; they are active against a wide range of gram-positive and gram-negative bacteria. The new 4-quinolones bind to DNA (9) Blood samples for cytogenetic analysis were taken before the start of treatment from all patients, after 1 week of treatment from the first group, and after 2, 4, 6, and 10 weeks of treatment from the second group.The blood samples were cultured for 48 h at 37°C in 10 ml of McCoy 5A medium with 20% fetal calf serum according to a standard method. Chromosome preparations were stained with Giemsa stain. One hundred metaphases from each individual and sampling occasion were analyzed on coded slides by two investigators, and the aberrations were recorded according to the ISCN nomenclature system (7). When difficulty arose in the classification of an aberration, a second opinion was sought. Such cells were never rejected, and agreement between the two observers was required

Twenty‐eight individuals occupationally exposed to ethylene oxide have been compared with 20 controls regarding cytogenetic effects in peripheral blood lymphocytes and in bone marrow cells. The exposure levels of ethylene oxide were estimated and none of the individuals had, during the last 2.5 years, been exposed to workroom air concentrations exceeding 1 ppm. The exposed persons showed significantly increased levels of chromosome aberrations in lymphocytes (about 50% increase of mean) and of micronuclei in erythroblasts and polychromatic erythrocytes (about 100% and 300% increase of mean, respectively) when compared with controls. However, sister chromatid exchanges and micronuclei in lymphocytes did not show any significant effect of exposure. A significant effect of smoking on micronuclei in erythroblasts and lymphocytes was found. There were several statistically significant, positive correlation coefficients among the different cytogenetic parameters.

Sister chromatid exchanges (SCE) and structural chromosome aberrations were analyzed in peripheral blood lymphocytes and correlated to smoking habits of 91 individuals. There was no difference between smokers and nonsmokers, neither as regards the frequency of SCE, nor for the frequency of structural chromosome aberrations in the total material. In a subgroup exposed to epoxy resins, though, a significantly elevated number of SCE among the smokers was noted. Conversely, smoking did not have any effect as regards SCE among individuals exposed to ethylene oxide-the exposure group with the highest level of SCE. Thus, although there may be an association between smoking habits and the SCE rate in certain populations, this is apparently not a general phenomenon.

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