An investigation of the mutagenic potential of pulsed ultrasound.

The possible mutagenic effect of microsecond pulses of ultrasound was investigated using 3 MHz ultrasound at diagnostic dosages, and also under conditions of increased pulse repetition frequency and acoustic power output. The first part of the study involved 5 strains of Salmonella typhimurium bacteria in which mutagenicity and viability were assessed using the Ames test, while functional competence was evaluated from microscopic observations of motility. No changes were observed in survival, in the incidence of mutants, or in microbial motility following irradiation with ultrasound intensities of 4.5 W/cm2 at temperatures ranging from 37 degrees to 43 degrees C. In the second part of this study, the frequency of sister chromatid exchange (SCE) in Chinese hamster ovary (CHO) cells, treated with similar ultrasound dosages, remained unaltered when cells were irradiated at temperatures up to 41 degrees C. At 43 degrees C and above, cell division was arrested by hyperthermia, an effect unrelated to ultrasound.