Sister chromatid exchange frequency in human lymphocytes after long duration exposure to pulsed ultrasound.

The aim of this study is to determine whether sister chromatid exchange (SCE) frequency increases in human lymphocytes that are exposed to pulsed ultrasound conditions within the range typically employed in ultrasound Doppler measurements of fetal blood flow. Whole blood diluted with culture medium was exposed in vitro to 3.1 MHz pulsed ultrasound at spatial peak pulse average (SPPA) intensities from 15 to 135 W/cm2. Insonation for 5 min did not significantly alter the base level frequency of SCEs compared to that observed in sham-insonated controls. To avoid missing an effect, due to differing sensitivities of the division stages within the mitotic cycle, insonation was also applied for 24 hr to include one complete cell division cycle. No change in SCE was observed after this extended insonation at SPPA intensity of 33 W/cm2.