Cytotoxic and Cytogenetic Effect of Low-Frequency Sound Impulses

Objective: High levels of infrasound can occur in workplaces wherever machines are operated that spread large vibrations. This is frequently combined with audible low-frequency sound. So far, the biological effects of infrasound have only been partially known. In the present study, cytotoxic and cytogenetic effects of infrasonic impulses on cells were investigated. Methods: Test cells were peripheral human lymphocytes, which were cultivated for 48 h before the start of the experiment. Panserin was used as basic medium. 10% fetal calf serum, L-glutamine, antibiotics and phytohemagglutinin were admixed to the medium. After PHA stimulation and subsequent cultivation, mostly T lymphocytes which had already passed through 2-3 cell cycles after 48 h at the start of the experiment proliferated during the first days. After the pre-cultivation, the infrasound exposure took place at a distance of 3, 6 and 12 m for the duration of 30, 120 and 300 sec. In addition, cultures without infrasonic impact were used as controls. Results: No indications of cytotoxic effects can be found after determination of the mitotic indices. Compared to the controls, there is a fourfold frequency of condensation errors at 30 and 120 seconds of sound exposure at a distance of 3 m. As a cytogenetic effect, a duplication of the rate of tetraploid metaphases (4n-metaphases) for 3 m can already be seen at 30 sec. At 120 sec, duplications of the 4n rates also show at a 6 and 12 m distance. The controls indicate no changes in the rate of tetraploidy. Conclusion: Despite significant mechanical impacts of the sound source, especially on the lymphocyte cultures at 3 m and 6 m distance, no cytotoxic effects could be detected according to the criteria of the mitotic index. A correlation between the infrasonic exposure and the rate of tetraploid metaphases is obvious.