Bioeffects and safety of low frequency ultrasound

Bioeffects and safety of US have long been a concern and have been thoroughly investigated for high frequency US used in medical procedures. With increasing applications of low frequency ultrasound (LFUS, 20-100 kHz), it has become imperative to expand safety considerations to cover this frequency range. The authors have investigated the biological effects of LFUS on human blood, suspended cultured cells and the auditory system of guinea pigs to establish safe limits of exposure, which, according to current results, are consistent with the established limits at both ends of the frequency range, namely audible sound and high frequency diagnostic/therapeutic medical US.