Increased sister chromatid exchanges in Chinese hamster ovary cells exposed to high intensity pulsed ultrasound.

This study comprised two repeat experiments in which Chinese hamster ovary (CHO) cells were exposed to nominal peak intensity Im = 2500 W/cm2, 2.5 MHz, pulsed ultrasound. Cells contained in a 0.53 cm diameter chamber in 0.48 cm thick Plexiglas were exposed to 10 microseconds pulses at 200 Hz prf in 9 sites for 3 min per site for a total duration of 27 min. The -3 dB focal beamwidth was 0.115 cm at an axial distance of 4.8 cm. Analysis of the pooled data from each series of experiments showed a statistically significant increase in the mean frequency of sister chromatid exchanges (SCE) in exposed compared to control cells. The results show a high degree of variability in the controls and insonated samples, which suggests that large numbers of insonations may be required in studies with SCE to reduce the high probability of missing an effect. The results of this series of experiments provide the first confirmation of an increase in SCEs following exposure to pulsed ultrasound.