William Taylor

Measurement of vibration of hand-held tools: weighted or unweighted?

The standards for hand-arm vibration have evolved from research studies in the late 1960s and were based on discomfort and tolerance levels. The lower frequencies were more intolerant and were weighted accordingly. The vascular and neurologic components of the hand-arm vibration syndrome may develop independently, and recent epidemiologic studies have shown both underestimation and overestimation in the incidence of Raynauds phenomenon from the International Standard Organization dose-response criteria with respect to different tools. The validity of the current International Standard Organization, British Standards Institute, American National Standards Institute, and The American Conference of Governmental Industrial Hygienists Threshold Limit Values is therefore questionable. The weighted and unweighted frequency spectra of various hand-held tools are presented in this paper. It is concluded that, until such time as more dose-effect data become available, unweighted measurements should be determined. Furthermore, the frequencies measured should be extended to 5 kHz.

Noise levels and hearing thresholds in the drop forging industry

A-weighted equivalent continuous noise levels for hammer and press operations in a drop-forging industry were determined using both tape recordings of the noise and personal noise dosimeters. The results indicated average A-weighted Leq values of 108 dB for hammer operators and 99 dB for press operators. Comparison of hearing level statistics for 716 hammer and press operators and 293 control subjects indicated the severe hazard to hearing of impact noise exposures. For mean exposure times of less than 10 years, hearing levels for the press (99 dB) and hammer (108 dB) operator age groups are nearly identical, and in the latter case are less than those predicted for exposure to equivalent continuous noise. For long-term exposures of 10 years or more, the results of this study indicate that hearing losses resulting from impact noise in the drop-forging industry are as great or greater than those resulting from continuous noise.

Biological effects of the hand–arm vibration syndrome: Historical perspective and current research

The objective of this paper is to highlight gaps of information regarding mechanisms of vascular, neurological, and musculo-skeletal damage caused by vibration. Also addressed is evidence that high noise level may act synergistically to the development of vibration syndrome of the hand and arm. Areas of research currently active in psychophysical and neurophysiological investigations to increase our understanding of tactile and spatial discrimination are discussed. Although the importance of sensory loss or fine touch is understood, there is neither a proven objective scientific test with which the syndrome can be diagnosed nor is there a scale of damage assessment. Determining the exact role of the central nervous system in assessing damage from vibration is difficult in view of nonspecific symptoms reported from eastern Europe and from Japan. To complicate matters still further, there is the possibility that repeated, rapid mechanical movements of the hand and arm associated with handling heavy tools produce carpal tunnel syndrome but that the injury is not directly attributed to vibration. Therefore, it follows that there could exist an element of carpal tunnel syndrome in many vibration syndrome cases.

Investigation of a population exposed to organomercurial seed dressings.

Urinary mercury and protein output rates, together with serum phosphoglucose isomerase activity, in 33 cereal seed dressers in East Scotland, employed seasonally, were compared with 33 age-matched controls. Increased mercury urinary concentrations, significant low-grade proteinuria, and inhibition of serum phosphoglucose isomerase were found. Blood mercury concentrations were significantly higher than normal controls. The enzymic activity of glutathione reductase in the sera of the seed dressers was within the normal range. There were no significant abnormalities in the electrocardiographic recordings in the seed dressers. The pathological and prognostic significance of these abnormalities is uncertain, but the results indicate the need for stricter protective measures.

Biological effects of vibration on the hand and arm: Historical perspective and current research

Raynauds phenomenon of occupational origin, or the vibration syndrome of hand and arm, was first recognized in North America by Dr. Alice Hamilton in the limestone quarries of Bedford, Indiana around 1890 to 1900. It is a tribute to the American pioneers in this area that the Acoustical Society of America now formally recognizes Biological Response to Vibration as a technical area. The objective of this paper is to highlight gaps of information regarding mechanisms of vascular, neurological, and musculo‐skeletal damage caused by vibration. Also addressed is evidence that high noise level may act synergistically to the development of vibration syndrome of the hand and arm. Areas of research currently active in psychophysical and neurophysiological investigations to increase our understanding of tactile and spatial discrimination are discussed. Although the importance of sensory loss or “fine touch” is understood there is neither a proven objective scientific test with which the syndrome can be diagnosed nor is there a scale of damage assessment. Determining the exact role of the central nervous system in assessing damage from vibration is difficult in view of nonspecific symptoms reported from Eastern Europe and from Japan. To complicate matters still further, there is the possibility that repeated, rapid mechanical movements of the hand and arm associated with handling heavy tools produce Carpal Tunnel Syndrome but that the injury is not directly attributed to vibration. Therefore, it follows that there could exist an element of Carpal Tunnel Syndrome in many vibration syndrome cases. Clearly, there is an area within the framework of the Acoustical Society of America for worldwide cooperative efforts to solve many fundamental problems concerned with the effect of vibration on a hand or arm.

Epidemiologic study of foundry and shipyard workers exposed to vibration from hand‐held pneumatic tools

A total of 451 workers in three foundries and one shipyard representing all workers using pneumatic chipping and grinding tools, together with a control population, were surveyed for the signs and symptoms of vibration syndrome. The results of a questionnaire and medical examination (to exclude all other causes of Raynauds Phenomenon) showed that hourly workers at the shipyard had a prevalence of vibration syndrome of 19% and a latency of 17 years while foundry hourly workers had a prevalence of 28% and a latency of 1 year. Incentive foundry chipper and grinder groups had prevalences that ranged from 40% to 67% while latencies ranged from 1.5 to 3 years. Vibration measurements proceeded simultaneous to the medical study, and showed acceleration levels on the pneumatic chipping hammer of 2400 g(rms) on the chisels and 30 g(rms) on the handles in the frequency range of 6.5–1000 Hz. Pneumatic grinders varied depending on maintenance conditions from 0.5 to 79 g(rms) over the same frequency range. Recommendat...