Prevalence Of Vibration-induced White Finger Research Articles

Exposure-response relation for vibration-induced white finger: effect of different methods for predicting prevalence.

A pooled analysis of vibration-induced white finger (VWF) in population groups of workers has been performed using the results of a published meta-analysis as source material (Nilsson T, Wahlström J, Burström L. Hand-arm vibration and the risk of vascular and neurological diseases a systematic review and meta-analysis. PLoS One. 2017:12(7):e0180795. https://doi.org/10.1371/journal.pone.0180795). The methods of data selection follow those described previously by Scholz et al. (in Scholz MF, Brammer AJ, Marburg S. Exposure-response relation for vibration-induced white finger: inferences from a published meta-analysis of population groups. Int Arch Occup Environ Health. 2023a:96(5):757-770. https://doi.org/10.1007/s00420-023-01965-w) to enable comparison with the results of the present work. The analyzed epidemiologic studies contain different prevalences of VWF observed after different durations of employment involving exposure to the vibration of power tools and machines. These prevalences are transformed to 10% prevalence by either linear or polynomial (i.e. "S"-shaped curvilinear) interpolation in order to compare with the exposure-response relation contained in the relevant international standard (ISO 5349-1:2001). An exposure-response relation is constructed using regression analysis for the time (in years) to reach 10% prevalence in a population group, when subjected to a daily vibration exposure calculated according to the procedures specified in the standard, A(8). Good fits to the data are obtained when polynomial and linear prevalence interpolation is used. The 95-percentile confidence intervals (CIs) of the exposure-response relation predicted by polynomial prevalence interpolation lie at somewhat larger lifetime exposures than those obtained by linear prevalence interpolation. Uncertainty in the precision of polynomial prevalence interpolation is mitigated by giving equal weight to linear interpolation when interpreting the results. When the 95-percentile CIs of the exposure-response models obtained by linear and polynomial prevalence interpolation are used to define the most probable exposure-response relation, the resulting common range of values includes the ISO exposure-response relation. It is proposed that an exposure-response relation for the onset of VWF derived from a regression analysis is specified in terms of the lower limit of its CI. Hence, when exposure measures are constructed according to the ISO standard and equal weight is given to the results of the 2 methods for interpolating prevalence described here, the ISO exposure-response relation would be considered to provide a conservative estimate for a 10% prevalence of VWF to develop in a population group, at least for A(8) > 4 m/s2. It thus remains the relation to use for assessing exposure to hand-transmitted vibration in the workplace. Additional research is needed to resolve inconsistencies in the ISO method for calculating daily exposures.

A Follow up Study on the Consequences of VWF Patients in Workers Using Chain Saws in Japanese National Forests

A Follow up Study on the Consequences of VWF Patients in Workers Using Chain Saws in Japanese National Forests: Makoto Futatsuka, et al. Department of Public Health, Kumamoto University School of Medicine—The authors carried out more than 20 yr of follow up studies of vibration‐induced white finger (VWF) from the time the use of chain saws ceased. A total of 496 workers who were affected by VWF during the period 1955‐82 were followed up to observe the consequences of VWF. These subjects were selected from a total of 1,586 chain saw operators who had used chain saws as a professional operator during some of the years from 1955 to 1982 in the national forests on Kyushu Island, Japan. In 1997 the authors had verified the current status and the course of VWF by direct interviews. A life table Product Limit method analysis of VWF prevalence was carried out to describe the consequences of VWF from the time the use of chain saws ceased. Out of the total number of subjects it was possible to follow 488 workers (98.4%) to ascertain their current states. Fourhundred and eighty‐one (98.6%) workers had retired and of these 124 (25.4%) had died. The rate of prevalence of VWF fell continuously after the use of chain saw ceased from 29.3% to a final value of 18.8% after more than 20 years' observation. It was observed that the percentage prevalence depended significantly on the severity: 87% for the subjects with stage 3, 53% for stage 2 and 17% for stage 1. The time course of the rate of recovery from moderate VWF differed from that of severe VWF. Peripheral neuropathies and sympathetic disturbances were predominantly observed in severe stage VWF cases in pathophysiological examinations.

Proposal for hand-arm vibration exposure limits adopted for Japanese workers operating hand-held vibration tools.

On the basis of data presented in our previous, reports, the current study was undertaken to estimate frequency-weighted hand-arm vibration exposure limits for various daily exposure times. The procedures for the present study were as follows. (1) The prevalence of vibration-induced white finger (VWF) as well as the vibration exposure were investigated in various groups of workers operating hand-held vibrating tools. The vibration magnitude of various tools was measured and the results were presented as the energy-equivalent frequency-weighted root-mean-square (m/s2 rms) acceleration. There was a statistically significant positive correlation between the prevalence of VWF and the measured vibration magnitude (R2 = 0.5, P < 0.05). Hence, it was concluded that in decisions concerning quantitative recommendations for vibration exposure, the prevalence of VWF should be considered. (2) By a careful selection of available publications which contain useful information on duration of vibration exposure of < or = 2 h/day and the occurrence of VWF, a significant correlation between the prevalence of VWF and the vibration magnitude could be observed. The regression equation was estimated as: y = -18.5 + 4.6 (x), R2 = 0.8. On the basis of this equation, it was speculated that the prevalence of VWF in workers using vibrating tools might be restricted to the prevalence of Raynaud's phenomenon in the Japanese general population if the 2-h daily vibration exposure is about 4.5 m/s2 rms. (3) Regarding this speculation, the equation provided in the documentation of ISO 5349 was used and modified as: [alpha h,w)eq,t = (alpha h,w)eq,2(2/t)1/2 (m/s2 rms)] and then the vibration limit values for daily exposure of 1 min to 8 h were calculated. (4) In order to achieve compatibility with standards of other countries, and to formulate an easy method for using the recommended values presented here, the daily exposure time of 8, 4, 2, 1 and 0.5 h were selected. The correspondence vibration magnitudes were in the range 22-9.0 m/s2 rms, and the lower limit (2.2 m/s2 rms) was assumed as the permissible vibration exposure limit for an 8-h working period. The proposed daily vibration limits were then compared with those recommended by other institutions.

Pathophysiology of Vibration‐Induced White Finger and Safety Levels for Hand‐Transmitted Vibration

Pathophysiology of Vibration‐Induced White Finger and Safety Levels for Hand‐ Transmitted Vibration: Ryoichi Inaba, et al. Department of Hygiene, Gifu University School of Medicine—This review addresses the pathogenic mechanism and vibration safety values of vibration‐ induced white finger (VWF). Sympathetic hyperactivity alone has long been postulated to account for VWF, but damage to vasoregulatory structures and functions in the finger skin now also seems to be involved. The physiological complexity of the response to cold is so great and the interaction between various vasoregulatory mechanisms so intricate that only a multifactorial etiology and pathogenesis is likely for VWF. These factors will be discussed in detail. Regarding vibration safety values, the prevalence of VWF and vibration magnitude (hand‐transmitted vibration levels (HTVLs)) in various groups of workers which reported in our previous studies were reviewed. The prevalence rates of VWF were compared to the prevalence rates of Raynaud's phenomenon (RP) in a large group of males and females without vibration exposure. It was observed that in subjects exposed to HTVLs of between 1.1 and 2.5 m/s2, the prevalence of VWF was 0.0‐4.8%. The prevalence of VWF in workers exposed to HTVLs of up to 5.1 m/s2 was 9.6% and significantly higher than the prevalence of RP in males in the general population (2.7%). A significant positive correlation between VWF and HTVLs values was obtained. By employing the results obtained on vibration magnitude and the prevalence of VWF, estimated vibration safety levels are discussed.

Dose-response relation for vascular disorders induced by vibration in the fingers of forestry workers.

To study the relation between the prevalence of vascular disorders (white finger) and vibration exposure in a group of 222 forestry workers, of whom 164 (73.9%) had work experience limited to antivibration (AV) chain saws only and 58 (26.1%) had operated both non-AV and AV chain saws. The chain saw operators and 195 control workers never exposed to hand transmitted vibration were interviewed with health and workplace assessment questionnaires. The diagnosis of vibration induced white finger (VWF) was made on the basis of subjective symptoms of finger blanching and the results of a cold test with plethysmographic measurement of systolic blood pressure of the finger. Vibration was measured on a representative sample of AV and non-AV chain saws. Daily vibration exposure was assessed as eight hour energy equivalent frequency weighted acceleration (A(8)). A lifetime vibration dose was estimated for each of the forestry workers. The overall prevalence of VWF among the forestry workers was 23.4%. The diagnosis of VWF was made in 13.4% of the forestry workers who handled only AV chain saws and in 51.7% of those who had also operated non-AV chain saws in the past. Raynaud's phenomenon was found in 2.6% of the controls. In the forestry workers, the risk for VWF showed positive increments with each increment of vibration dose, suggesting a monotonic dose-response relation. The responsiveness to cold in the digital arteries of the forestry workers was also found to increase with increasing vibration dose and severity of VWF. The estimated relation between VWF and vibration exposure showed that the expected prevalence of VWF increased almost linearly to either A(8) (with exposure duration unchanged) or the number of years of exposure (with equivalent acceleration unchanged). In this study of VWF among forestry workers, the estimated dose-response relation showed that if the magnitude of vibration acceleration is doubled, the total duration of exposure should be halved to produce an equivalent effect. On the basis of the assessment of vibration exposure, the estimated risk for VWF in the study population was found to be lower than that predicted by the international standard ISO 5349. These findings suggest a revision of the risk estimates for VWF currently provided by ISO 5349.

Hand-arm vibration syndrome and dose-response relation for vibration induced white finger among quarry drillers and stonecarvers. Italian Study Group on Physical Hazards in the Stone Industry.

To investigate the occurrence of disorders associated with the hand arm vibration syndrome in a large population of stone workers in Italy. The dose-response relation for vibration induced white finger (VWF) was also studied. The study population consisted of 570 quarry drillers and stonecarvers exposed to vibration and 258 control stone workers who performed only manual activity. Each subject was interviewed with health and workplace assessment questionnaires. Sensorineural and VWF disorders were staged according to the Stockholm workshop scales. Vibration was measured on a representative sample of percussive and rotary tools. The 8 h energy equivalent frequency weighted acceleration (A (8)) and lifetime vibration doses were calculated for each of the exposed stone workers. Sensorineural and musculoskeletal symptoms occurred more frequently in the workers exposed to vibration than in the controls, but trend statistics did not show a linear exposure-response relation for these disorders. The prevalence of VWF was found to be 30.2% in the entire group exposed to vibration. Raynaud's phenomenon was discovered in 4.3% of the controls. VWF was strongly associated with exposure to vibration and a monotonic dose-response relation was found. According to the exposure data of this study, the expected percentage of stone workers affected with VWF tends to increase roughly in proportion to the square root of A(8) (for a particular exposure period) or in proportion to the square root of the duration of exposure (for a constant magnitude of vibration). Even although limited to a specific work situation, the dose-response relation for VWF estimated in this study suggests a time dependency such that halving the years of exposure allows a doubling of the energy equivalent vibration. According to these findings, the vibration exposure levels currently under discussion within the European Community seem to represent reasonable exposure limits for the protection of workers against the harmful effects of hand transmitted vibration.

Prevalence of Raynaud's phenomenon in different groups of workers operating hand-held vibrating tools.

In eight groups of subjects operating various hand-held vibrating tools and aged from 30 to 59 years, the prevalence rates of vibration-induced white finger (VWF) and numbness, pain, or stiffness in the upper and lower extremities were investigated. Hand-transmitted vibration levels (HTVLs) were measured on the back of the hand, by means of unidirectional (x-axis) vibration dosimeters, and the frequency-weighted acceleration levels [(Lh,w)eq,t] were determined as the vibration levels. The prevalence rates of VWF and numbness of the hands in these subjects were compared to the prevalence rates of Raynaud's phenomenon (RP) and numbness of the hands in 1027 males and 1301 females not occupationally exposed to vibration (age range: 30-59 years). It was observed that in subjects exposed to HTVLs of between 1.1 and 2.5 m/s2, the prevalence of VWF was between 0.0% and 4.8%. The prevalence of VWF reached 9.6% in a group of workers exposed to HTVLs of 2.7-5.1 m/s2. The latter group showed a significant difference (P < 0.05) in the prevalence of VWF compared to the 2.7% prevalence of RP in male subjects of the general population. The prevalence of VWF in female subjects exposed to vibration (4.3%) was not significantly different from the prevalence of RP in females of the general population (3.4%). The prevalence rates of numbness of the hands were in the range of 6.5%-30.4% in the exposed groups and in the range of 13.4%-29.5% in the general population. Among the subjective symptoms, only VWF showed a significant positive correlation with HTVLs (R2 = 0.5, P < 0.05). It was concluded that in decisions concerning quantitative recommendations for vibration exposure, the prevalence of VWF should be employed. With a view to decreasing the risk of developing VWF, estimated vibration safety values for 4 h and 2 h daily exposures are discussed.

Health risk assessment of noise, hand-arm vibration and cold in railway track maintenance

Health risk assessment of noise, vibration and cold was carried out in track maintenance workers in Finland. A health survey among 252 workers and noise and vibration measurements of tools used in track maintenance work was performed, and audiograms were examined from 117 workers. Hand-held tamping machines had caused most of the exposure to noise and vibration in the track maintenance work. The present results showed how important it is also to take into account preventive and contributory factors when health risks are assessed. The predicted risk of hearing damage was 24%, but the observed value in a clinical study was only 15%, obviously due to the effect of hearing protectors. The prevalence of vibration-induced white finger (14%) was predicted quite well with the ISO 5349 standard, but no method was available to assess the risk of nerve disorders. The results showed that there are many limitations in health risk assessment used, e.g. behaviour and protection facilities had a great influence on the risk of frostbite.

Vibration-induced white finger as a risk factor for hearing loss and postural instability.

Effect of vibration-induced white finger (VWF) on the hearing was examined in 289 Japanese forest workers. From 51 subjects suffering from VWF and 228 with no history of VWF, 37 pairs were formed, matched for age and hours of noise exposure. The cases with VWF had a significantly higher hearing threshold at 4 and 8 kHz than their matched controls. This result was corroborated by the follow-up study which showed significant deterioration of hearing at 2 and 4 kHz only in subjects with VWF during five-year follow-up period. The possible effects of VWF on the postural stability were investigated in 71 Finnish forest workers. Postural stability was evaluated by an average velocity of the body-sway (ASV) measured with a force platform technique. Neither age nor exposure duration to chain saw noise and vibration correlated with ASV. A significant positive correlation was found between ASV and hearing level at 4 kHz after allowing for the effects of the exposure. Multiple regression analysis of ASV on age, exposure hours, hearing level at 4 kHz and prevalence of VWF showed that the hearing level and VWF had significant and almost significant effects on ASV, respectively. Thus, the workers suffering from VWF developed greater hearing loss and the hearing loss correlated with ASV. VWF explained some variance of ASV in the regression analysis. VWF seemed to play some role in hearing deterioration and possibly in genesis of balance disorder.

Vibration syndrome among Finnish forest workers between 1972 and 1990.

A longitudinal study on vibration syndrome among professional forest workers was carried out in Finland from 1972 to 1990. In the course of the follow-up the weighted vibration acceleration of chain saws decreased from about 14 to 2 m/s2. The prevalence of vibration-induced white finger (VWF) decreased gradually from 40% to 5%. Numbness occurred mainly at night, and its prevalence decreased from 78% to 28%. During part of the follow-up period (1975-1990) the complaints of hand muscle weakness decreased from 19% to 9%. Disorders of the musculoskeletal system were considered to cause more disability than VWF. The decreased vibration acceleration and the lighter weight of chain saws were considered the main reasons for the decrease in the prevalence of vibration-induced symptoms.

Vibration Exposure, Vibration-Induced White Finger and Digital Arterial Tone in Chain Saw Operators

In a group of 65 Italian forestry operators using chain saws, the overall prevalence of vibration-induced white finger (VWF) was found to be 29.2%. The occurrence of VWF was higher in the chain sawyers who had operated non-antivibration (non-A/V) as well as A/V saws (46.4%) than in those with experience limited to A/V saws (16.2%). The latency time before VWF averaged 9.4 yr (SD 6.8). The mean value of the four-hour energy-equivalent frequency-weighted acceleration [(ah,w)eq(4)] was 7.2 m/s2 (SD 1.2). On the basis of the known VWF prevalence and of [(ah,w)eq(4)], a latent period before VWF of 7.1 yr was expected according to ISO 5349. The measurement of finger systolic pressure (FSP) at 15°C and 10°C by plethysmographic technique showed that the chain sawyers affected with VWF experienced a more intense digital vasospasm than a group of comparable controls and the chain sawyers without VWF. The sensitivity of the method to detect vibration-induced digital arterial hyper-responsiveness to cold was 84.2% and the specificity was 100%. The findings of this study showed a good agreement between the expected and observed latency times before VWF, even though the ISO dose-effect relationship seems to overestimate slightly the risk. The results of the cold test indicated that the measurement of FSP during local cooling is an accurate laboratory method to diagnose objectively Raynaud's phenomenon of occupational origin.

Cohort study of vibration-induced white finger among Japanese forest workers over 30 years

A retrospective longitudinal study was undertaken to evaluate the changes in the prevalence of vibration-induced white finger (VWF) during the period from 1955 to 1988 among a population of Japanese state forestry workers. Since the late 1970s, technical improvements in the engine and the introduction of devices to dampen vibration have reduced the acceleration of chain saw handles from 20 ms−2 rms to less than 3 ms−2 rms. During the study period, the peak prevalence rate was 30.9% in 1973 and 17.2% in 1988. The peak prevalence rate was 54.8%, found in the exposure cohort beginning in 1959–1960 and the peak incidence rate was 5.65 per 100 person year in 1965–1966. Beginning with the 1969–1970 exposure cohort, both the prevalence and the incidence rate decreased significantly. During the study period, prevalence rates were approximately 10, 20, 30 and 35% after 4, 6, 10 and 12 years of exposure, respectively. The latent interval for the development of VWF was 6.2 ± 3.9 years on average, and the duration of VWF was 13.1 ± 7.5 years on average through the 1988 observation period. The 1950 cohort group had a long latent interval and a long prevalent period. On the other hand, the late 1960 cohort group had a short latent interval and a short prevalent period. Of 535 study subjects with VWF during the 20 observation years (prevalence rate: 41.0%), the recovery rate was 38.9% on average from the time of cessation of exposure.

振動障害患者の上下肢の冷え，しびれの自覚症状の解析

Coldness and numbness of the lower limbs in patients with vibration syndrome were studied in correlation with the frequency of attacks of vibration-induced white finger (VWF), coldness and numbness of the upper limbs, and awakening at night due to numbness of the arm. Subjects were 229 patients aged 50-69 years without disease other than vibration syndrome who had mainly operated chain saws. The present study showed that patients with more frequent VWF attacks had a higher prevalence and frequency of coldness in the fingers, awakening at night due to numbness of the arm, and coldness and numbness in the legs. Particularly patients having almost daily attacks of VWF had a high prevalence of these symptoms. Positive correlation was observed in prevalence and frequency between coldness of the fingers and that of the legs, and between coldness and numbness in the legs. The prevalence of VWF, numbness and coldness of the fingers, and coldness of the legs was higher the longer the total chain saw operating period. The present findings suggest that patients with severe circulatory disturbances in the upper limbs have severe circulatory disturbance in the lower limbs. Further studies on circulatory disturbances in the lower limbs are indicated, and their mechanism involved should be also pursued from the pathogenetic point of view.

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

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 less than 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 VWF than in those without VWF and in the controls.

Assessment of vibration levels associated with hand-held roadbreakers.

The hand-held roadbreaker plays a vital role in enabling the British gas distribution workforce to install gas supply pipework. Hence, any potential problem which could lead to a restriction of the use of this equipment would present pipework installation departments with serious operational problems. A test program was therefore set up to enable risks to operators to be quantified. The vibration levels measured exceeded proposed limits laid down in current guidelines for vibration exposure. If these limits were realistic, a high prevalence of vibration-induced white finger (VWF) would have been expected. However, a survey of the workforce using the roadbreakers indicated a VWF prevalence of 20 times less than that predicted by the guidelines. It was concluded that a possible explanation could be that the current frequency-weighting factors used in the guidelines are inappropriate for application to this type of equipment with dominant frequencies below 25 Hz. The application of the current weighting factors to the test data produced during the program led to high weighted acceleration values and unrealistic dose-response relationships. It is proposed that the application of the various guidelines to the use of this equipment be reconsidered.

Vibration syndrome among Finnish forest workers, a follow-up from 1972 to 1983.

A longitudinal survey on the prevalence of vibration syndrome among professional forest workers was conducted from 1972 (118 workers) to 1983 (206 workers). The prevalence of vibration-induced white finger (VWF) was 40% among the workers in 1972; it gradually declined to 5% in 1983. Three new workers developed VWF symptoms during the follow-up period. They had only used saws equipped with antivibration handles. The prevalence of VWF has decreased mainly due to the reduction of chain-saw vibration. The prevalence of paresthesias of the hands and arms declined from 78% in 1972 to 37% in 1976, and then increased to 51% in 1983. The recent increase was thought to be due to static muscle load and the ageing of the workers. No correlation was found between the severity of VWF and peripheral nerve symptoms. No significant changes in muscle fatigue occurred during the follow-up period; it was present in about 10-15% of the workers. The forest workers subjectively assessed musculoskeletal load and strain as being more harmful than the symptoms of vibration syndrome. The preventive measures aimed at reducing chain-saw vibration, implemented since 1970, have been beneficial and explain the decreased prevalence of VWF.

Vibration exposure and vibration-induced white finger due to Chain Saw operation

A longitudinal study was undertaken to evaluate changes in the prevalence of vibration-induced white finger (VWF) during the period 1956 to 1980 among a population of Japanese state forestry workers. The vibration levels in the measurements occasionally exceeded the 30-minute line proposed by the Draft International Standard ISO/DIS 5349 in one-third octave bands mainly centered on 160 Hz, with 500 Hz in vertical, 400 Hz in sideways, and 250 Hz in back-and-forth sawing operations. The peak prevalence rate was 62.6%, found in the cohort beginning in 1958-1959. Beginning with the 1968-1969 cohort, the prevalence decreased significantly. During the study period, prevalence rates were approximately 10%, 15%, 20%, 25%, 30%, 35%, and 40% after 2, 3, 4, 5, 7, 9, and 12 years of exposure, respectively. The incidence rate increased gradually after 1960 and the peak value was reached in 1966. The peak value of the incidence rate by duration of exposure was about the same (8% to 10%) in the 1958, 1962, and 1966 cohorts; however, in later groups, the incidence rate decreased in the earlier stages of the exposure periods. The latent interval for the development of VWF was 6.4 +/- 3.7 years (6,000 to 7,000 hours) on average, with a 90% range of one to 14 years (700 to 16,000 hours). Of 452 study subjects with VWF (prevalence rate, 33.5%), 13.5% recovered within the exposure periods, 12.2% recovered within one year after the cessation of exposure, and 74.3% still had VWF more than two years after exposure had ended.(ABSTRACT TRUNCATED AT 250 WORDS)

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

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 X s-2.

Effect of the air hammer on the hands of stonecutters. The limestone quarries of Bedford, Indiana, revisited.

In the limestone quarries of Indiana, USA, pneumatic percussive hammers replaced the mallet and hammer around 1900. By 1917 the air hammer was being used exclusively for periods of eight to ten hours a shift. In 1918 Alice Hamilton investigated an unusual "disease" in these stonecutters of Bedford, Indiana, who complained of "attacks of numbness and blanching of the fingers coming on suddenly under the influence of cold and then disappearing." The prevalence of vibration induced white finger (VWF) found in this population of 38 stonecutters was 89%, with decreased light touch, pain, and temperature appreciation in advanced cases. In 1978 a VWF research team revisited these limestone quarries. During the 60 year interval the stonecutting industry had contracted from 4000 workers in 40 quarries in 1918 to 3-400 in 10 quarries in 1978, with only 50 employees remaining in the Bedford area. In a population of 30 stonecutters the prevalence of VWF in 1978 was 80%, with similar sensory loss in light touch, pain, and temperature appreciation. Between 1918 and 1978 no change had taken place in the design of the air hammers used for stonecutting. Vibration levels of 4859 metres/s2 on the chisel, and 2010 metres/s2 on the barrel were measured over a frequency range 6.3 to 1000 Hz. The fundamental frequency was 75 Hz. These measured vibration levels are outside the ISO/DIS/5349 (1979) recommended limits for human exposure to vibration transmitted to the hand. The VWF data presented in this paper, and those originally reported by Hamilton in 1918, call for an immediate redesign of stonecutting pneumatic hammers in order to remove one cause of Raynaud's phenomenon of occupational origin.

Prevalence of vibration-induced white finger in fluorspar mines in Weardale.

A combined epidemiological and clinical study of vibration-induced white finger (VWF) was carried out involving 115 men in four fluorspar mines. The overall prevalence of VWF was found to be 50% among 42 vibration-exposed subjects, while that of constitutional white finger (CWF) was 5-6% in all men studied. The VWF latent interval was 1-19 years with a mean of 5-6 years. An association was observed between the exposure time and VWF stages which included 18 men in Stage 0, three in the intermediate Stage of 0T/0N, five in Stage 2 and 16 in Stage 3; no men were seen at Stage 1. Among those with VWF in Stage 3, the index, middle and ring fingers were affected in both hands and the little fingers and thumbs were last to be involved. Clinically, on general examination, apart from vibration-induced white finger, the men in the 'vibration' group were not as healthy as those in the 'control' group. The circumference of the index fingers was not significantly different for the different groups. Neurological tests showed that the ridge test and, to a lesser extent, the two-point discrimination and the light touch tests, could be regarded as useful for the diagnosis of VWF.