The effect of cold, acceleration and frequency on the circulatory and sensory systems of the hand and the transmission of acceleration through the hand and arm

Approximately 1.4 million persons are affected by hand-arm vibration in the United States with prevalences of vibration syndrome ranging from 6 to 100% in persons exposed to vibration. The disease affects the peripheral vascular and neural systems and may be associated with musculo-skeletal damage, hearing loss, and carpal tunnel syndrome. The study determined the amount of vibrational acceleration transmitted from a known emission source through the upper limb by the use of accelerometers mounted to the skin at the 3rd metacarpophalangeal joint, the ulnar styloid process, the olecranon and the acromion of the right arm. Three levels of acceleration (4, 16, and 100 m/s$\sp2$), three levels of frequency (67, 163, and 1000 Hz), and three levels of ambient temperature (45, 57.5, and 70$\sp\circ$ F) along with two gender levels were used as independent variables. Input acceleration and input frequency were found to have a significant effect on the transmission of acceleration. Measurements at the metacarpophalangeal joint for 63 and 160 Hz found that the ratios of output to input acceleration were greater than 1.0 indicating that measurements taken only on the tool may underestimate the actual risk to the worker. Also investigated were the effects the independent variables had on blood flow, as measured by finger temperature, vibration sensation thresholds, and subjective ratings of discomfort, tingling and numbness. Ambient temperature had a significant effect upon the changes in finger temperature, vibration sensation threshold and ratings of tingling but not on ratings of numbness and discomfort. A significant but small correlation was found between the transmission of acceleration and vibration threshold sensation and ratings of tingling, numbness and discomfort. The results of the study indicate a need to reevaluate the current ISO and ANSI standards concerning hand-arm vibration exposure