Rheological and immunological findings in dockers with vibration-induced white fingers

Summary The aim of the present study was to characterize theological and immunological features involved in the pathogenesis of vibration-induced white fingers (VWF). Plasma viscosity, at two shear rates (580 s^–1 and 1164 s^–1), levels of immunoglobulins (IgG, IgM, IgA), circulating immune complexes, rheumatoid factor, antinuclear antibodies, fibronectin, fibrinogen, hemoglobin and erythrocyte sedimentation rate were analysed in 30 male dockers with VWF and in 30 healthy male referents unexposed for hand-arm vibrations. Decreased plasma viscosity was observed among the men with VWF, although formal significance (P < 0.05) was only obtained at shear rate 580 s^–1. The decrease was mainly seen among smokers. In the study there were no significant differences between the VWF group and the referents with regard to immunoglobulin levels, autoantibodies and other plasma proteins. From the study it is concluded that workers with VWF may have a decreased plasma viscosity. The biological relevance of this observation is uncertain and deserves further study.     

Prevalence of vibration-induced white finger and assessment of vibration exposure among travertine workers in Italy

Summary Among 76 stonedrillers and stonecutters/chippers working in the Rapolano travertine quarries (Tuscany, Italy), 27 subjects (35.5%) were affected with vibration-induced white finger (VWF). The median latent period for VWF was ten years (range 0.1–26 years). A VWF prevalence of 8% was found among 60 comparable controls (P < 0.0001). Vibration measurements showed that the frequency-weighted accelerations for two rock-drills and two small chipping hammers ranged from 19.7 to 36.4 m/s². Weighted accelerations between 2.4 and 4.1 m/s². were measured on the handles of a vertical grinder and a hand cutter. Vibration data, daily exposure time and total duration of exposure period were used to calculate two indicators of vibration dose such as the four-hour, energy-equivalent, frequency-weighted acceleration (m/s²) and the vibration exposure level (dB). A significant association between the vibration exposure level and the severity of VWF stages was observed among the travertine operators. The dose-effect relationship proposed by ISO 5349 was not suitable for the data of the present study because it overestimates the risk due to hand-transmitted vibration in the travertine workers. Finally, the results of a cold test indicated that the rewarming time of fingertips to room temperature was more prolonged in the operators with VAT than in those without VWF and in the controls.     

Epidemiological survey of shipyard workers exposed to hand-arm vibration

Summary All 169 caulkers employed at a ship yard were examined to determine the prevalence of vibration syndrome due to pneumatic portable tools (chipping hammer and grinders).Vibration measurements and medical investigations were performed in the field between September 1977 and July 1978.Vibration spectra recorded on pneumatic tools were compared to ISO Draft Proposal No. 5369. The chipping hammer produced the highest acceleration levels and exceeded the maximum ISO limits even for a short exposure time (30 min per shift).The results of medical investigations pointed out that 78.7% of caulkers experienced paresthesia in their hands, 31.3% Raynaud's phenomenon (or VWF), 20.1% presented with radiological signs of osteoarthritis at wrist and shoulders, 10.0% with olecranon exostoses, and 31.3% with cysts of the carpal bones.To diagnose VWF the skin temperature of the hands were recorded in all 169 caulkers and 60 controls at the shipyard. The basal skin thermometric map (recorded in 16 positions per hand) demonstrated an average difference of 2–2.5°C between the two populations.The thermometric curve, monitored every 3 min for 40 min after a provocative cold-test (immersion of hands and wrists in melting ice for 2 min), well differentiated workers exposed and not exposed to vibrations.The authors emphasize that skin temperature (before and after the coldtest) are suitable for epidemiological purposes to compare the prevalence rates of VWF in control-experimental groups.The results of this study were presented at the International Symposium on Man Under Vibration, Suffering, and Protection, Udine (Italy), 3–6 April 1979     

Longitudinal study on factors related to the course of vibration-induced white finger

 Follow-up surveys were conducted in 1982 and 1988 to investigate factors affecting the course of vibration-induced white finger (VWF). Subjects were 353 patients, aged 40 to 70 at the start of the 1982 survey, who were receiving treatment for hand-arm vibration syndrome. Between 1982 and 1988, the attacks of VWF decreased, while numbness and pain in the hand changed slightly. Finger skin temperature showed a tendency to increase, but recovery time in nail compression tests was unchanged. Vibration perception threshold and grasping power tended to become worse. Of the 177 patients with VWF in 1982, 55 (31%) had no VWF in 1988. The improvement in VWF depended on its severity assessed by the frequency of attacks, the extent of the affected finger phalanges and the Stockholm vascular (V) stage at the start of the 1982 survey. The improvement was observed in 46% of the 1V (mild) stage cases, against only 17% of the 3V (severe) stage cases. Patients in the 2V (moderate) and 3V stages had lower finger skin temperature than those without VWF (the 0V stage). Patients with milder VWF seemed more likely to improve. Continued use of vibratory tools was found to be an unfavourable factor for improvement of VWF. Age, smoking and drinking habits, and medical complications showed no significant effects on the course of VWF. Received: 26 February 1996/Accepted: 2 May 1996     

Cutaneous signs (Raynaud's phenomenon,sclerodactylia, and efladema of the hands) and hand-arm vibration exposure

Summary Dermatological tests and examinations of the hand(s) were carried out in vibration-exposed and un exposed males. The subjects were 179 chain-saw workers in private forestry companies and 205 local inhabitants who had never used vibrating tools. The prevalences of Raynaud's phenomenon (RP), sclerodactylia, and edema of the hands were estimated in both groups, and associations between these cutaneous signs and vibration exposure were evaluated. The prevalences of RP and edema in the exposed group were 9.5% and 1.7%, respectively, and in the unexposed group, 2.9% and 1.5%, respectively. Sclerodactylia was seen in 31.8% of the chain-saw workers but in only 6.4% of the unexposed individuals. In statistical analyses based on unconditional logistic regression models with adjustment for age, RP was associated with long-term ( 20 years) vibration exposure [odds ratio (OR) = 7.06; 95% confidence interval (CI) = 2.51–19.87]. Sclerodactylia was associated with both short- and long-term vibration exposure (OR = 6.54, Cl = 3.30-13.36; OR = 7.05; CI = 3.41-14.60, respectively). There were significant dose-response relationships between RP and duration of exposure and between sclerodactylia and duration of exposure. Results of function tests indicated a longer recovery time and a higher vibration threshold for the workers with RP. The presence of sclerodactylia, however, did not have any significant influence on function test results. It is possible to conclude that not only RP but also sclerodactylia could be induced by vibration exposure. However, most cases of sclerodactylia were not so serious as to involve disturbances of peripheral circulatory and nerve function.     

Risk assessment of vibration exposure and white fingers among platers

Summary The dose-response relationship between vibration exposure and vascular disorders in the hands was examined in platers. The study was based on a cross section of 89 platers and 61 office workers divided according to exposure to vibration into four groups. Vibration exposure was assessed by measuring the acceleration intensity on a sample of tools, together with both subjective rating and objective measurements of the exposure time. The frequency-weighted energy equivalent acceleration for 4 h was 4.6–4.7 m/s². The point prevalence of white fingers was 42% for the plater category currently exposed with an odds ratio of 85. The time laps before contraction of white fingers (latency time) was four years for the 10th percentile, and was shorter than predicted according to the ISO-5349 standard. The prevalence of white finger symptoms staged according to the Taylor-Pelmear scale was comparable to the prevalences according to the Stockholm Workshop Scale. Vibration exposure was the dominant source of white fingers and each year of vibration exposure increased the odds ratio for white fingers by 11%. Distal circulation in the hands was assessed by a timed Allen test. The odds ratio for a positive Allen test was higher for the workers exposed to vibration compared to the non-exposed workers. The use of the timed Allen test is suggested in the clinical examination for vibration white fingers. The observed high risk for contracting white fingers could be prevented by exposure level reduction and/or restriction of exposure duration.     

Circulatory disturbances of the foot in vibration syndrome

Summary Circulatory disturbances of the foot in patients with vibration syndrome were studied by measuring the skin temperature of both index fingers and great toes through a 3-min immersion of the right foot in cold water at 10°C. Subjects included 11 patients with vibration-induced white finger (VWF) [VWF(+) group], 12 patients without VWF [VWF(–) group], and 20 healthy referents not exposed to vibration. Patients were all male chain saw operators who had scarcely been exposed to vibration of the foot. The prevalence of coldness felt in the upper and lower extremities was > 90% in the VWF(+) group, about 60% in the VWF(–) group, and < 10% in the referents. The extent of the coldness was greatest in the VWF (+) group. The skin temperature of both fingers and toes was lowest in the VWF(+) group, somewhat higher in the VWF(–) group, and highest in the referents both before and after immersion. These findings indicate that patients with vibration syndrome, especially those with VWF, have circulatory disturbances in the foot as well as in the hand. The disturbances in the foot may be related to long-term repeated vasoconstriction in the foot induced by hand-arm vibration through the sympathetic nervous system.     

Raynaud's phenomenon of fingers and toes of miners exposed to local and whole-body vibration and cold

Summary In a study of 27 underground miners exposed to hand or whole-body vibration, cold or other vasoconstrictive environmental factors, higher prevalences of Raynaud's phenomenon in both fingers and toes were found than in a control group not exposed to vibration. There were no Raynaud-like phenomena among miners not exposed to vibration. There was a positive correlation between the two locations. This may mean a general susceptibility of vasospasm, but it seems more probable that the disorders are caused by vibration exposure to fingers and toes.     

Significance of finger coldness in hand-arm vibration syndrome

Objectives To evaluate the relationship between subjective symptoms of coldness in fingers and peripheral circulation in patients with hand-arm vibration syndrome (HAVS). Methods Thirty-five male patients confirmed to have HAVS as an occupational disease took part in this study. Their mean age was 62 years (SD 5) and all were chain-saw operators exposed to vibration for an average of 25 years. Their annual health examination included the history of their daily habits (smoking, drinking, and therapeutic exercise), report of subjective symptoms such as coldness, numbness and tingling in the fingers, and a physical examination; laboratory tests consisted of skin temperature measurement, and pain and vibration perception under conditions of cold provocation. A frequently used method of cold provocation, immersion of the left hand up to the wrist in water of 10°C for 10 min, was used. Results Finger coldness was classified into 3 groups according to its severity: mild group (n=8), moderate group (n=17) and severe group (n=10). There was no significant difference in age or occupational background between the groups. A significant association was found between finger coldness and prevalence of Raynaud's pheno menon (p<001, χ²). The mean skin temperature was significantly lower with the severity of finger coldness (ANOVA, p<0.05). In the cold provocation test, there was no significant difference between skin temperature and coldness at 5 min and 10 min after immersion, though a difference was observed immediately after immersion. No significant difference was observed in the relationship between finger coldness and vibrotactile threshold before, during or after the cold provocation test. Conclusions The severity of coldness in the fingers is significantly related to skin temperature. The severity of finger coldness reflects the extent of peripheral circulatory vasoconstriction. Coldness in the fingers may be a good warning of potential problems in peripheral, circulatory function.     

Symptoms of contruction workers exposed to whole body vibration and local vibration

Summary To study the effects of construction machinery operation on subjective symptoms, a questionnaire survey was caried out among construction machinery operators by a self-reporting method. Subjects were 184 power shovel operators, 127 bulldozer operators, 44 forklift operators as operator groups, and 44 office workers as a control. Their ages were in a range of 30–49 years. The questionnaire contained 20 symptoms referring to fatigue, digestive problems, and upper or lower limbs or back problems. The prevalence rate and symptom characteristics were examined. The dominant symptoms of the operator groups were stiff shoulder, low back pain, and stomack symptoms. The prevalence rate of low back pain was significantly different between forklift operators and controls. No significant differences were found in the symptoms of upper limbs and fingers between operator groups and controls. The prevalence of Raynaud's phenomenon was 0.5%–2.3% in the operator groups and 2.3% in the control group.     

Immunologic studies on the pathogenesis of Raynaud's phenomenon in vibration disease

Summary These examinations were designed to explain the role of immunologic reactivity in the pathogenesis of Raynaud's phenomenon due to vibration. Patients were divided into 3 groups: 81 with positive and 50 with negative Raynaud's phenomenon in vibration disease, and 37 with Raynaud's disease in patients not exposed to mechanical vibration. In the Raynaud's-positive group, increase of beta globulins, gamma globulins, and antiglobulin antibodies were found. The cold hemagglutinin reaction was detected more often in the Raynaud's-positive, than in the Raynaud's-negative group. IgG serum concentration in persons with prodromal symptoms and IgG immunoglobulins in the developed form of vibration disease was significantly increased. The role of the immunologic basis of Raynaud's phenomenon due to vibration was taken into consideration.     

A minireview of studies conducted in Japan using finger-skin temperature during cold-stress tests for the diagnosis of hand-arm vibration syndrome

For the diagnosis of the hand-arm vibration syndrome, cold-stress tests using different water temperatures and periods of hand immersion have been investigated in Europe, North America, and Japan. In recent years, peripheral circulation and sensory tests, including finger-skin temperature measurement involving immersion of one hand in cold water at 10 °C for 10 min, have been widely accepted in Japan. On the other hand, standardization of the vascular assessment method is under discussion at the International Organization of Standardization. We reviewed research findings from Japan concerning finger-skin temperature measurement during the cold-stress test, especially factors influencing the test results and the diagnostic significance. For establishment of the cold-stress test for epidemiology studies of the hand-arm vibration syndrome, standardization of the environmental factors influencing the test results and reporting of its sensitivity and specificity are needed. Received: 2 July 1998 / Accepted: 17 January 1999     

Preliminary evaluation of dose-effect relationships for vibration induced white finger in Japan

Summary Habitual use of many vibrating tools has been found to be connected with the appearance of various disorders affecting the blood vessels, nerves, bones, joints, muscles or connective tissues of the hand and forearm. The vibration exposures required to cause these diseases are not known exactly, either with respect to vibration intensity and the vibration frequency spectrum, or with respect to daily exposure time and total exposure period. The purpose of this study is to investigate available data on the physical conditions in Japan that have caused vibration induced white finger (VWF) and attempt to establish approximate relationships between vibration conditions and prevalence of VWF. The vibration conditions were evaluated using the method of vibration assessment recommended by the International Standardized Organization, which uses the weighted vibration level of the frequency weighted, dominant, single axis component of vibration directed into the hand. A clear correlation between level, prevalence of VWF and exposure period can be found. The results also suggest the relationship between the weighted levels and latent intervals. These dose-effect relationships enable the prediction of the average latent interval for a population group and the range of progression of the disorders—all from a measurement of the vibration entering the hands. In Japanese cases, 4, 8, and 15% of VWF prevalence correspond with 10, 20, and 40% of VWF prevalence in the Draft International Standard ISO/DIS 5349 (1982) within the weighted vibration level range of 2 to 50m · s^¨.     

Bone and joint disorders in the upper extremities of chipping and grinding operators

Summary X-ray examinations of the wrists, the elbows and the shoulders were carried out on 67 vibration-exposed foundry workers and on 46 comparable referents performing heavy manual work. Both groups had a mean age of 39.6 years. Musculoskeletal symptoms, such as arthralgias of the wrist and elbow joints, muscle pain and decreased muscular force, were found to be significantly increased in the chipping and grinding workers compared with the referents. After adjustment for age, the prevalence of cysts in the metacarpal and carpal bones was almost the same in the two groups, whereas radiological signs of osteoarthritis in the wrist joint were more frequent among the vibration-exposed workers (P < 0.025). The overall prevalence of radiographic abnormalities in the elbow joint was higher in the vibration group than in the reference group (P < 0.025). Olecranon spurs were observed in 50.7% of the exposed operators and in 28.2% of the referents (P < 0.025). No difference in the prevalence of radiological changes in the shoulder could be demonstrated between the populations studied. In both groups injuries of bones and joints were not associated with age. Among the chipping and grinding operators, a slight but not significant trend in the prevalence of skeletal abnormalities with increasing vibration exposure was observed. The results of this study indicate that the foundry workers using vibrating tools were affected with bone and joint disorders in the elbow and, to a lesser extent, in the wrist, which occurred more frequently than was observed in unexposed referents, who performed solely heavy manual activity. Among the vibration-exposed workers, no relationship between radiological changes in the upper limbs and symptoms of vibration white finger was found, pointing out that different pathogenic mechanisms are involved.     

Vibration-induced white finger syndrome and carpal tunnel syndrome among Finnish metal workers

Objective  Officially 10–26 cases of vibration-induced white fingers (VWF) have been reported annually in Finland. It has been suggested that the numbers are underestimated. The purpose of the present study was to estimate the cumulative exposure to hand–arm vibration (HAV) and the prevalence of clinically diagnosed cases of VWF and carpal tunnel syndrome (CTS) in a population of Finnish metal workers and to determine the symptoms and clinical tests that would best predict the diagnosis. Methods  A questionnaire on vibration exposure at the workplace and symptoms of the upper extremities was sent to a sample (n = 530) of members of the local Metalworkers Union. Those who reported finger blanching, numbness or tingling of the fingers or symptoms of CTS were invited to take part in clinical examinations. Their cumulative lifelong exposure to HAV was evaluated. Those whose symptoms referred to VWF or CTS were given a cold provocation test with the measurement of finger systolic blood pressure and electroneuromyography of the upper arms. Results  Altogether 285 metal workers (54%) responded to the questionnaire, and 24 new cases of VWF (8.4%) and 12 cases of CTS (4.2%) were diagnosed. In the group of VWF patients, seven workers had both VWF and CTS. All of the workers diagnosed as having VWF also had numbness or tingling in their fingers. Consequently, questions concerning numbness and tingling, a two-point discrimination test, Phalen’s test, and Tinell’s test had a high predicting value for VWF. The exposure time of the VWF cases did not differ significantly from that of the study group as whole, but the cumulative exposure index was significantly higher. Conclusion  The results suggest that VWF is underdiagnosed in Finland. In screening for the health effects of HAV, sensorineural symptoms of hands should be carefully inquired about and examined in patients complaining of white fingers. More education on the recognition and evaluation of HAV exposure and its health effects is needed.     

Pathophysiology and classification of the vibration white finger

Skin, arteries and nerves of the upper extremities can be affected by vibration exposure. Recent advances in skin and vascular biology as well as new investigative methods, have shown that neurovascular symptoms may be due to different vascular and neurological disorders which should be differentiated if proper management is to be evaluated. Three types of vascular disorder can be observed in the vibration white finger: digital organic microangiopathy, a digital vasospastic phenomenon and arterial thrombosis in the upper extremities. An imbalance between endothelin-1 and calcitonin-gene-related peptide is probably responsible for the vasospastic phenomenon. Moreover, paresthesiae can be due to either a diffuse vibration neuropathy or a carpal tunnel syndrome. A precise diagnosis is then necessary to adapt the treatment to individual cases. A classification describing the type and severity of the vascular lesions is presented. Asymptomatic lesions are included for adequate epidemiological studies and risk assessment of vibrating tools. Monitoring of vibration exposed workers should include not only a questionnaire about symptoms, but also a clinical evaluation including diagnostic tests for the screening of early asymptomatic neurovascular injuries. Received: 17 September 1998 / Accepted: 24 July 1999     

Measuring method for vibration perception threshold of fingers and its application to vibration exposed workers

Summary A measuring method for the vibration perception threshold (VPT) of fingers has been developed. The VPTs of 118 and 149 professional forest workers were measured during a compulsory annual health examination in 1979 and 1983, respectively. Also the VPTs of eight pedestal grinders, who were suffering vibration-induced white finger (VWF), were measured in 1979 and 1983. The control group consisted of 20 research workers who had no vibration exposure in the past and no symptoms in their hands. The measuring system for VPT gave repeatable results. The frequency of the most sensitive VPT of vibration exposed workers alternated between 63 and 125 Hz instead of 125 Hz of subjects without vibration exposure. The VPT of the pedestal grinders and forest workers with decreased hand grip force and with vibration-induced white finger were significantly higher than those of the controls. The VPTs of the forest workers decreased slightly and that of the grinders increased from 1979 to 1983. In spite of long vibration exposure in the past and continuing lower level vibration exposure, the increased VPT of forest workers does not seem to be permanent.     

The clinical grading of Raynaud's phenomenon and vibration-induced white finger: relationship between finger blanching and difficulties in using the upper limb

OBJECTIVES: To investigate the association between functional difficulties in using the upper limb and extent and frequency of finger blanching, and the merits of these markers in grading the severity of Raynaud's phenomenon (RP) and vibration-induced white finger (VWF). METHODS: A questionnaire was mailed to a randomly selected community sample of 22,194 working-aged adults. Information was collected on cold-induced finger blanching--including the extent and frequency of attacks in the past year, and on difficulty in using the upper limb in several everyday activities (e.g. doing up buttons, opening a tight screwtop jar, and pouring from a jug). Associations were examined by logistic regression with the resultant odds ratios converted into prevalence ratios (PRs) and 95% confidence intervals (95% CI). RESULTS: Among 12,907 respondents were 1,359 who reported finger blanching and provided details of its extent and frequency. Of these, 7.4% reported frequent attacks (50 or more over the year), and 12% reported extensive blanching (affecting nine or ten digits). After adjustment for potential confounders, subjects with finger blanching reported an excess of difficulties in using the limb. Thus, in men with blanching the PR for difficulty with buttons was 4.7 (95% CI 3.9-5.8), and that for pouring from a jug was 3.8 (3.0-4.9) in comparison with men who had never had blanching. Similar associations were found in women and in those men with exposure to hand-transmitted vibration. The risk of reporting difficulties increased markedly with frequency of blanching--up to four- or fivefold in those with 50 or more attacks in the past year compared with those who had none; but differences by extent were less marked, with PRs < or = 1.6 in those with nine to ten digits affected compared with one to two digits. CONCLUSIONS: RP and VWF are both associated with difficulties in using the upper limb in everyday tasks. Further investigation of potential reporting biases is warranted, but if the associations are causal, frequency of attacks influences impairment more than extent of disease. More account may need to be taken of frequency of blanching episodes in assessing and in compensating subjects with VWF.     

Measurement, evaluation, and assessment of peripheral neurological disorders caused by hand-transmitted vibration

Regular exposure to hand-transmitted vibration can result in symptoms and signs of peripheral vascular, neurological and other disorders collectively known as the hand-arm vibration syndrome. The measurement of the effects of hand-transmitted vibration involves converting the evidence of disorder (symptoms and signs) into information that can be stored. Evaluation requires the use of scales on which to indicate the severity of the various symptoms and signs. Assessment involves a judgement of severity relative to a criterion, usually for a specific purpose (e.g. to decide on removal from work or compensation). The measurement and evaluation of symptoms and signs is necessary when monitoring patient health and when performing epidemiological studies for research. The assessment of the severity of the hand-arm vibration syndrome is currently performed with staging systems, but the criteria are not clear and not related to defined methods for measuring or evaluating the symptoms and signs. Recognizing that similar symptoms can occur without injury from occupational exposures to hand-transmitted vibration, this paper attempts to define significant peripheral neurological symptoms caused by hand-transmitted vibration (i.e. 'unusual symptoms') and how these symptoms and related signs may be measured. Scales for evaluating the symptoms (e.g. their extent) and the related signs (e.g. their probability relative to the probability of the sign being present in persons not exposed to vibration) are defined. A method of relating unusual symptoms to both the signs of disorder and the pattern of vibration exposure is illustrated. Assessments of severity will vary according to the reasons for assessing the health effects of vibration, and will depend on local practice and convenience, but a way of combining evaluations of symptoms and signs is demonstrated in a staging system. Although inherently complex, the methods may assist the collection of data required to improve understanding of the effects of hand-transmitted vibration and also support a more complete reporting of the condition in those adversely affected by hand-transmitted vibration.     

Lessons from hand-arm vibration syndrome research

This paper addresses many of the salient issues and difficulties encountered in performing Hand-Arm Vibration Syndrome research since its discovery in the early 1900's by Alice Hamilton. The areas discussed and the resulting lessons learned include the medical, epidemiological, and control aspects of HAVS. The authors conclude with a plea to health professionals to be ever vigilant and responsive to the HAVS problem, or else it will continue unabated into the next century, an overall time span of nearly 100 years.