"Hand–arm vibration syndrome (HAVS) is an occupational disorder caused by years of exposure to hand-transmitted vibration from powered tools. Patients with late-stage HAVS have peripheral neuropathy with loss of nerve fibers. To protect workers from developing HAVS, ISO 5349 (2001) sets vibration exposure limits based on vibration ‘frequency weighting' which progressively reduces injury potential at 16 Hz and higher. A rat-tail vibration model was used to characterize the early changes in tail-nerves exposed to 30, 120 and 800 Hz vibrations continuously for 4 h at 49 m/s2 rms and to determine whether nerve damage is less at higher frequency. All three frequencies caused similar nerve edema, dilation of arterioles and percentages of disrupted myelinated axons. Eight hundred Hz alone caused edema of the endothelial and smooth muscle cells of nerve arterioles. These findings demonstrate that early vibration injury of nerves occurs at both low and high frequencies."

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