Lack of ultrasound effect on in vitro human lymphocyte sister chromatid exchange

The frequency of sister chromatid exchanges (SCEs) in human lymphocytes cultured in vitro was not affected by a 30 min exposure to a 2.25 MHz focused ultrasound beam (from a clinical diagnostic unit with a pulse repetition rate of 1000 Hz, a 1 mu sec burst duration, and a 2-200 W/cm2 maximum intensity). A 30 sec exposure to continuous wave 1 MHz 2 W/cm2 (SP) ultrasound from an experimental device lysed 10-15% of the lymphocytes; there was no increase in SCEs in the survivors relative to unexposed controls. Treatment of lymphocytes with 0.033 micrograms/ml mitomycin-C, a known SCE inducer, increased the frequency of SCEs about 4 times above control levels.