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Objective The aim of this study was to compare the performance of alternative measures of cumulative lifetime vibration dose to predict the occurrence of low-back pain (LBP) outcomes in a cohort of 537 professional drivers investigated at baseline and over a two-year follow up period. Methods The exposure data obtained in the EU VIBRISKS project were used to calculate alternative measures of either acceleration- (external) or force- (internal) based lifetime vibration doses. Vibration was measured in representative samples of machines and vehicles used by the drivers. Internal lumbar forces were calculated by means of anatomy-, posture-, and anthropometry-based finite element models. The relations of LBP outcomes to alternative measures of lifetime vibration doses were assessed by the generalized estimating equations method. Results Metrics of cumulative vibration exposure constructed with either acceleration- or force-based methods were significantly associated with the occurrence of LBP outcomes. A measure of model fitting suggested that force-based doses were better predictors of LBP outcomes than acceleration-based doses. Models with force root-mean-square doses provided a better fit to LBP outcomes than those with force-peak doses. Conclusions Measures of internal lumbar forces were better predictors of LBP outcomes than measures of external vibration acceleration although the exposure metrics constructed with the acceleration-based method have the advantage of greater simplicity compared to the force-based method. The differences between the models with force-based doses suggest that the cumulative health effects on the lumbar spine might depend on the integrated resulting total force over the entire exposure time rather than primarily on the force peaks.

Purpose: In the 30 years since the Stockholm Workshop Scale (SWS) was published, the scientific literature on hand-arm vibration syndrome (HAVS) has grown and experience has been gained in its practical application. This research was undertaken to develop an up-to-date evidence-based classification for HAVS by seeking consensus between experts in the field. Methods: Seven occupational physicians who are clinically active and have had work published on HAVS in the last 10 years were asked to independently take part in a three-round iterative Delphi process. Consensus was taken when 5/7 (72%) agreed with a particular statement. Experts were asked to provide evidence from the literature or data from their own research to support their views. Results: Consensus was achieved for most of the questions that were used to develop an updated staging system for HAVS. The vascular and neurological components from the SWS are retained, but ambiguous descriptors and tests without adequately developed methodology such as tactile discrimination, or discriminating power such as grip strength, are not included in the new staging system. A blanching score taken from photographs of the hands during vasospastic episodes is recommended in place of self-recall and frequency of attacks to stage vascular HAVS. Methods with the best evidence base are described for assessing sensory perception and dexterity. Conclusions: A new classification has been developed with three stages for the clinical classification of vascular and neurological HAVS based on international consensus. We recommend it replaces the SWS for clinical and research purposes.

Recently, a supplementary methodology to improve the assessment of occupational exposures to hand-transmitted vibration (HTV) and a revision of the clinical staging of the hand-arm vibration syndrome (HAVS) have been proposed. The Technical Report ISO/TR 18570:2017 provides guidance on a supplementary method to that defined in ISO 5349-1:2001 for measuring and reporting HTV exposures; the method provides an improved assessment methodology for evaluating vascular hand-arm vibration risks (vibration induced white finger). On using a Delphi procedure, an international panel of experts has achieved consensus to develop an updated staging system for the vascular and neurological disorders of the HAVS, previously defined in the Stockholm Workshop Scale (1986); a new classification has been proposed with three stages for vibration related vascular and neurological effects. This paper provides details on the new international criteria for the assessment of vibration induced vascular risk and for the clinical staging of the vascular and neurological components of the HAVS.Recentemente sono state proposte metodologie supplementari per la valutazione dell’esposizione a vibrazioni trasmesse al sistema mano-braccio e revisioni della stadiazione clinica dei sintomi vascolari e neurosensitivi della sindrome da vibrazioni mano-braccio. In particolare, (i) nel Technical Report ISO/TR 18570:2017 viene proposto un metodo supplementare per la predizione del rischio vascolare (fenomeno di Raynaud secondario) da vibrazioni manobraccio, ad integrazione della metodologia definita nello standard ISO 5349-1:2001; (ii) le esperienze accumulate in campo clinico e di laboratorio da parte di un panel internazionale di clinici del lavoro, appartenenti a istituzioni europee e nord-americane e attivi nei settori accademici e assistenziali per la diagnostica della sindrome da vibrazioni mano-braccio, hanno suggerito l’opportunità di procedere ad una revisione della stadiazione dei sintomi vascolari e neurosensitivi da vibrazioni mano-braccio precedentemente classificati nelle scale dello Stockholm Workshop 1986. In questo lavoro vengono riportati i nuovi criteri internazionali per la valutazione del rischio vascolare da vibrazioni mano-braccio e la stadiazione clinica della sindrome da vibrazioni mano-braccio.

PURPOSE: To provide an updated epidemiological validation for a supplementary method for assessing the risk of vascular disorders from hand-transmitted vibration. METHODS: The occurrence of vibration-induced white finger (VWF) in the vibration-exposed workers of the Italian cohort of the EU VIBRISKS study was related to measures of daily vibration exposure expressed in terms of r.m.s. acceleration magnitude normalised to an 8-h day, frequency weighted according to either the frequency weighting Wh defined in international standard ISO 5349-1:2001 [Ah(8) in ms- 2] or the hand-arm vascular frequency weighting Wp proposed in the ISO technical report (TR) 18570:2017 [Ap(8) in ms- 2]. To estimate a threshold value for vascular hand-arm vibration risk, the Wp-weighted vibration exposure value Ep,d (in ms- 1.5) was calculated according to the ISO/TR document. The difference in the predictions of VWF between the exposure measures calculated with the frequency weightings Wh or Wp was investigated by means of logistic modelling. RESULTS: Measures of daily vibration exposure constructed with the frequency weighting Wp [Ap(8) and Ep,d], which gives more importance to intermediate- and high-frequency vibration, were better predictors of the occurrence of VWF in the vibration-exposed workers than the metric derived from the conventional ISO frequency weighting Wh [Ah(8)]. There was some epidemiological evidence for a threshold value of Ep,d for the onset of VWF in the vibration-exposed workers. CONCLUSIONS: Measures of daily vibration exposure evaluated with the vascular weighting Wp performed better for the predictions of VWF than those obtained with the frequency weighting Wh recommended in ISO 5349-1.

In this study, the daily exposure action values (EAV) and the daily exposure limit values (ELV) for hand-transmitted vibration (HTV) and whole-body vibration (WBV), established by the EU Directive 2002/44/EC and the Italian Decree 81/2008, and expressed in terms of 8-hr frequency weighted r.m.s. acceleration magnitude, are discussed upon consideration of the findings of experimental and epidemiological studies.There is some epidemiological support for the EAV A(8) of 2.5 ms-2 r.m.s. and the ELV A(8) of 5 ms-2 r.m.s. for HTV, at least for the vascular component (secondary Raynaud's phenomenon) of the hand-arm vibration syndrome.There is some experimental evidence for the EAV A(8) of 0.5 ms-2 r.m.s. for WBV, while there is neither biodynamic nor epidemiological validation for the ELV A(8) of 1.15 ms-2 r.m.s. for WBV, this latter lowered to 1 ms-2 r.m.s. in the Italian legislation.In questo studio vengono discussi i valori giornalieri di azione (VA) e i valori limite di esposizione giornaliera (VL) per le vibrazioni trasmesse al sistema mano-braccio e le vibrazioni trasmesse al corpo intero, stabiliti dalla Direttiva EU 2002/44/CE e recepiti dal D.Lgs. 81/2008, ed espressi in termini di valore efficace (r.m.s) dell’accelerazione ponderata in frequenza normalizzata a 8 ore di lavoro (A(8)). I dati della letteratura epidemiologica tendono a supportare il VA A(8) di 2.5 ms-2 r.m.s. e il VL A(8) di 5 ms-2 r.m.s. per le vibrazioni mano-braccio almeno per la componente vascolare (fenomeno di Raynaud secondario) della sindrome da vibrazioni mano-braccio. Vi è qualche evidenza sperimentale per il VA A(8) di 0.5 ms-2 r.m.s. per le vibrazioni al corpo intero, mentre non vi sono elementi di validazione biodinamica o epidemiologica per il VL A(8) di 1.15 ms-2 r.m.s., opportunamente abbassato a 1 ms-2 r.m.s. nella legislazione italiana.

Background Regular exposure to hand-arm vibration can lead to hand-arm vibration (HAVS) and carpal tunnel (CTS) syndromes. EU Directive 2002/44/EC, which aims to improve surveillance and reduce exposure to vibration at work, defines exposure limits for hand-arm-vibration. The aim is to investigate whether the staged implementation of the directive since 2005 has been associated with a change in the incidence of HAVS or CTS in European countries. To model the range of potential outcomes of the intervention, we sought to define an exposure-risk relationship based on the best available prospective longitudinal data for exposed workers. Methods In a series of studies, which have been subject of previous publications, 1,2 forestry and stone workers were monitored at intervals of 1 to 5 years, on 1 to 4 occasions. Health status, annual hours of exposure and magnitude of vibration were recorded. In the present study, a novel analytical approach was applied to define a parametric survival function describing the incidence of HAVS as a function of various exposure metrics. Results Incidence of the vascular condition vibration-induced white finger was well described by a Weibull distribution with an increasing hazard rate. The resulting parametric equation reveals the role of duration of exposure and the vibration magnitude (m s-2) relative to a threshold magnitude. Conclusion The exposure-risk relationship, which differs in some respects from the exposure relationship described in current standards (e.g. ISO 5349-1, 2001), has a simple, mechanistically based form that can be easily applied to simulate the consequences of workplace interventions. References Bovenzi M. Int Arch Occup Environ Health 2008; 81 :401–408. doi:10.1007/s00420-007-0225-9 Bovenzi M. Int Arch Occup Environ Health 2010; 83 :259–272. doi:10.1007/s00420-009-0461-2

Objective The aim of this study was to investigate the performance of four frequency weightings for hand-transmitted vibration to predict the incidence of vibration-induced white finger (VWF). Methods In a longitudinal study of vibration-exposed forestry and stone workers (N=206), the incidence of VWF was related to measures of vibration exposure expressed in terms of 8-hour frequency-weighted energy-equivalent root-mean-square (rms) acceleration magnitude [A(8)] and years of follow-up. To calculate A(8), the rms acceleration magnitudes of vibration were weighted by means of four frequency weightings: (i) W(subscript h) (the frequency weighting specified in ISO 5349-1:2001); (ii) W(subscript h-bl) (the band-limiting component of W(subscript h)); (iii) W(subscript hf) (a frequency weighting based on finger vibration power absorption); and (iv) W(subscript hT) (a frequency weighting based on a Japanese study of VWF prevalence). The relations of VWF to alternative measures of vibration exposure were assessed by the generalized estimating equations (GEE) method to account for the within-subject dependency of the observations over time. Results Data analysis with a GEE logistic model and a measure of statistical fit suggested that calculating A(8) by weighting the tool rms accelerations with W(subscript h-bl) gave better predictions of the cumulative incidence of VWF than the other alternative measures of daily vibration exposure. Values of A(8) derived from the currently recommended ISO frequency weighting W(subscript h) produced poorer predictions of the incidence of VWF than those obtained with frequency weightings W(subscript hf) or W(subscript hT). Conclusions This prospective cohort study suggests that measures of daily vibration exposure which give relatively more weight to intermediate and high frequency vibration are more appropriate for assessing the probability of VWF.

The objective of this study was to investigate the relation between alternative measures of exposure to whole-body vibration (WBV) and low back pain (LBP) in professional drivers.The incidence of 12-month LBP, high pain intensity (numerical rating scale score5), and disability in the lower back (Roland and Morris disability scale scoreor=12) was investigated in a cohort of 537 drivers over a 2-year follow-up period. LBP outcomes, individual characteristics, and work-related risk factors were investigated by direct interview using a structured questionnaire. Daily vibration exposure was expressed in terms of either equivalent acceleration over an 8-h reference period [A(8), root-mean-square (r.m.s.) method] or vibration dose value [VDV, root-mean-quad (r.m.q.) method]. From the vibration magnitudes measured on vehicles and total exposure duration, seven alternative measures of cumulative vibration exposure were calculated for each driver, using expressions of the form Sigma a (i)(m)t(i), where a (i) is the frequency-weighted r.m.s. or r.m.q. acceleration magnitude on vehicle i(a(ws) or a (wq), respectively), t(i) is the lifetime exposure duration for vehicle i, and m = 0, 1, 2, or 4.In the drivers' cohort, the cumulative incidence of LBP outcomes were 36.3% for 12-month LBP, 24.6% for high pain intensity, and 19.2% for disability in the lower back. A transition model, which takes into account the temporal sequence of cause and effect and captures the longitudinal part of the relationship, showed that VDV performed better than A(8) for the prediction of LBP outcomes. After adjusting for potential confounders, test for trends suggested an increased risk for developing high pain intensity and disability over time (and, to a lesser extent, 12-month LBP) with the increases of cumulative vibration doses computed from lifetime exposure duration and r.m.q. vibration magnitude (i.e. Sigma[a (wqi)(m)t(i)]). Measures of exposure duration, either daily or lifetime, also provided good indications of risk for LBP outcomes over time. Physical work load, but not psychosocial environment, was significantly associated with the occurrence of LBP outcomes over time.Measures of vibration exposure derived from exposure duration (daily or lifetime) and r.m.q. acceleration magnitude (VDV, Sigma[a(wqi)(m)t(i)]) were better predictors of LBP outcomes over time than measures of vibration exposure including r.m.s. acceleration (A(8), summation operator[a(wsi)(m)t(i)]). Patterns of exposure-response relationship were more evident for the outcomes high pain intensity or disability in the lower back than for the binary response 12-month LBP.

Objectives To assess the usefulness of color charts for the diagnosis of finger whiteness in vibration-exposed workers. Methods A group of 146 forestry and stone workers exposed to hand-transmitted vibration (HTV) were examined twice over 1 year follow up period. The anamnestic diagnosis of finger whiteness was made on the basis of (a) a medical history alone, and (b) the administration color charts which showed changes in the skin color of fingers and hands. The cold response of digital arteries was assessed by measuring the change in finger systolic blood pressure (FSBP) after local cooling from 30 to 10C (FSBP%10). Results Assuming the administration of color charts as the gold standard, the sensitivity and specificity of the medical history alone to diagnose finger whiteness was 88.2 and 93.8%, respectively, at the initial cross-sectional study and 94.4 and 97.7% at the end of the follow-up. Random-intercept linear regression analysis of follow up data showed that after adjustment for several covariates, FSBP%10 was significantly associated with finger whiteness assessed by either medical history alone (P\0.005) or the color charts (P\0.001). However, a statistical measure of overall fit of regression models (Bayesian Information Criterion) suggested that the color chart method performed better than medical history alone for the prediction of the cold response of digital arteries. Conclusion The administration of color charts seems to reduce the proportion of false positive responses for finger whiteness in a population of vibration-exposed workers. The color chart method was a more significant predictor of digital arterial hyperresponsiveness to cold than medical history alone. These findings suggest that the use of color charts in clinical and epidemiological studies may be of help to assist in the diagnosis of finger whiteness in vibration-exposed workers.

Objectives To investigate the relation between manipulative dexterity and vibration exposure, ergonomic risk factors, and upper limb disorders in a group of workers exposed to hand-transmitted vibration (HTV). Methods Manipulative dexterity was investigated on 115 HTV workers (82 forestry workers and 33 stone workers) and 64 control men over 1-year follow-up period. The Purdue pegboard method was used to test manipulative dexterity which was scored for the dominant hand, nondominant hand, and both hands. Information about individual, work and health history was obtained by means of a standardised questionnaire. Vibration exposure was assessed in terms of tool vibration magnitudes, daily and total exposure duration, and cumulative vibration dose. Results On the cross-sectional investigation, Purdue pegboard scores were significantly lower in the HTV workers than in the controls (0.001 \ P \ 0.05). Over 1-year follow-up period, Purdue pegboard scores were found to be inversely related to age, smoking and use of vibratory tools (0.001 \ P \ 0.05). Moreover, deterioration of some measures of manipulative dexterity was significantly associated with sensorineural and vascular symptoms in the fingers of the HTV workers. Randomintercept linear regression analysis showed that Purdue pegboard scores decreased with the increase of vibration exposure. The reduction of assembly score (i.e. number of pins, collars, and washers assembled in a 60-s period) was significantly associated with the increase in vibration exposure and ergonomic stress (neck-upper arm posture, hand-intensive work, and total ergonomic score). Purdue pegboard scores tended to improve over the follow-up period in both the controls and the HTV workers, suggesting a possible learning effect over time. Conclusion The findings of this longitudinal study suggest an association between deterioration of manipulative dexterity and neurovascular symptoms in the fingers of HTV workers. There was evidence for a significant relation between loss of precise manipulation and exposures to hand-transmitted vibration and ergonomic risk factors.

Occupational exposures to vibration come in many guises, and they are very common at a population level. It follows that an important minority of working-aged patients seen by medical services will have been exposed to this hazard of employment. Vibration can cause human health effects, which may manifest in the patients that rheumatologists see. In this chapter, we identify the health effects of relevance to them, and review their epidemiology, pathophysiology, clinical presentation, differential diagnosis and vocational and clinical management. On either side of this, we describe the nature and assessment of the hazard, the scale and common patterns of exposure to vibration in the community and the legal basis for controlling health risks, and we comment on the role of health surveillance in detecting early adverse effects and what can be done to prevent the rheumatic effects of vibration at work.

OBJECTIVE: This cohort study aims to compare the performance of alternative frequency weightings of hand-transmitted vibration (HTV) for the assessment of the exposure–response relationships for neurosensory disorders and reduced work ability among HTV-exposed workers. METHODS: In a 3-year follow up study, the occurrence of neurosensory symptoms and reduced work ability, and the response to quantitative sensory testing (grip force, manipulative dexterity, touch sensation) were investigated in 249 HTV-exposed workers and 138 healthy controls. Among the HTV-exposed workers, the sensory outcomes were related to measures of daily vibration exposure expressed in terms of 8-hour energy-equivalent frequency-weighted acceleration magnitude [A(8)]. To calculate A(8), the acceleration magnitudes of vibration were weighted by means of four alternative frequency weightings of HTV. RESULTS: The occurrence of neurosensory symptoms, reduced work ability, and abnormalities of sensory tests was greater among the HTV-exposed workers than the controls. Among the HTV-exposed workers, the deterioration of neurosensory outcomes and the reduction of work ability increased on par with the measures of vibration exposure. Exposure–response models revealed that the four alternative frequency weightings of HTV provided the same predictions for the probability of finger numbness among the exposed workers (observed 36% versus predicted 32%). CONCLUSIONS: The findings of this study revealed significant dose–response relationships between measures of vibration exposure, sensory disorders, and reduced work ability among the HTV-exposed workers. There were no differences in the prediction of finger numbness between measures of vibration exposure calculated with alternative frequency weightings of HTV.

In a prospective cohort study of 537 male professional drivers, the occurrence of sciatic pain showed stronger associations with measures of internal lumbar load expressed in terms of daily compressive dose, S(ed) (MPa), and risk factor, R (non-dimensional), according to ISO/WD 2631-5 (2013), than with measures of daily vibration exposure calculated as either 8-h energy-equivalent frequency-weighted acceleration (ms(-2) r.m.s.) or vibration dose value (ms(-1.75)) according to the EU Directive on mechanical vibration (2002). Herniated lumbar disc, previous lumbar trauma and physical work load were also powerful predictors of the occurrence of sciatic pain over time. Psychosocial work environment was poorly associated with sciatic pain. The boundary values of risk factor (R) for low and high probabilities of adverse health effects on the lumbar spine, as proposed by international standard ISO/WD 2631-5 (2013), tend to underestimate the health risk in professional drivers.In a prospective cohort study of professional drivers, measures of internal spinal load were better predictors of the occurrence of sciatic pain than the measures of daily vibration exposure established by the EU Directive (2002). Herniated lumbar disc, lumbar trauma and physical work load were also associated with sciatic pain.

Introduction Epidemiological studies have provided strong evidence for an association between neck pain and awkward working postures [1]. There is also evidence for a causal relationship between highly repetitive work and neck and shoulder pain (NSP), and between neck disorders and forceful movements [1]. At present, epidemiological data are insufficient to provide support for a relationship of whole-body vibration (WBV) to NSP. Some studies have suggested that psychosocial factors at work and individual psychological distress may play a role in the development of NSP. The aims of this cohort study were to investigate the occurrence of NSP and the relation between NSP and individual- and work-related factors (WBV, physical load, psychosocial environment) in Italian professional drivers recruited in the EU VIBRISKS project [2]. Methods The study population included 537 male professional drivers of earth-moving machines, fork-lift trucks, and public utility vehicles. They were investigated over a two-year follow up period (2003-2006). Personal, occupational, and health histories were collected by means of the VIBRISKS questionnaire. NSP outcomes in the previous 12 months were treated as ordinal variables with four levels and assessed in terms of number of episodes (0, 1-5, 6-10, >10), duration (0, 1-6, 7-30, >30 days), and pain intensity (numerical rating scale (NRS) score: 0, 1-3, 4-5, 6-10). Cumulative WBV exposure was expressed as (awsi2ti) in m2s-4h, where awsi is the r.m.s. value of the vibration total value of the frequency-weighted accelerations measured on vehicle i driven for time ti in hours (hours/day  days/year  years). The following physical load factors were investigated: lifting (> 15 kg) with trunk bent or twisted, work with hands above shoulder level, driving with trunk bent or twisted. Psychosocial risk factors were expressed in terms of job decision, job support and job satisfaction. Psychological distress and psychosomatic symptoms were also investigated. The associations between NSP (ordinal) outcomes and individual- and work-related risk factors were expressed as proportional odds ratios estimated by random-intercept ordered logistic regression using time-lag models (i.e. NSP for subject i at time t (Yit) was related to predictor variable(s) k at time t – 1 (Xikt-1), i.e. the values of the predictors at one measurement earlier). Results At the initial survey, in the entire population of professional drivers the point prevalence of neck pain was 43.4%, and that of shoulder pain was 19.9%. The cumulative incidence rates for neck and shoulder pain over the follow-up period were 31.9 and 21.4%, respectively (Table 1). The incidence of high pain intensity (NRS score > 5) was 15.7% for the neck and 10.4% for the shoulder. At some points of the follow-up period there were cases of neck or shoulder pain who reported recovery from symptoms. As a result, the occurrence of persistent neck and shoulder pain in the study population (calculated over period prevalence) was 78.8 and 65.3%, respectively. After adjustment for potential confounders, cumulative WBV exposure was significantly associated with NSP outcomes (episodes, duration, intensity) over the follow-up period (Table 2). Frequent awkward postures while driving were significantly related to the frequency and severity of neck pain, while lifting with trunk bent or twisted > 45 min/day was associated with the duration of neck pain. Tasks involving prolonged exposures to lifting with awkward postures (>45 min/day) and work with hands above shoulder level (>1 h/day) were strongly associated with nearly all shoulder outcomes. Limited job decision and job dissatisfaction were significant predictors of episodes of neck pain over time, and low social support was related to pain intensity in the neck. Perceived psychosocial work factors were not significantly associated with shoulder outcomes even though there was some evidence for a positive trend. Psychological distress was strongly related to all NSP outcomes over the follow-up period. There were no significant interactions between work-related risk factors when appropriate product terms were included in multivariate data analysis. Conclusions The findings of this prospective cohort study tend to confirm that neck and shoulder outcomes are of multifactorial origin in a population of professional drivers. Cumulative WBV exposure, physical load factors and adverse psychosocial environment seem to contribute independently of each other to the development of neck and shoulder disorders in driving occupations. References [1] NIOSH. Musculoskeletal disorders and workplace factors – a critical review of epidemiologic evidence for work-related musculoskeletal disorders of the neck, upper extremity, and low back. DHHS (NIOSH) Publication No. 97-141. Cincinnati, OH, 1997. [2] VIBRISKS. Final Technical Report. (www.vibrisks.soton.ac.uk).

To investigate whether prior exposure to hand-transmitted vibration on the day of a cold provocation test affects the cold response of digital arteries.Each of ten healthy men attended two experimental sessions in which their right hands were exposed for 60 min to either contact force alone (5 N) or a combination of contact force (5 N) and 125-Hz vertical vibration with an acceleration magnitude of 64 m s(-2) r.m.s. (unweighted). Finger systolic blood pressure (FSBP) during local cooling to 10 degrees C was measured in the second right finger (exposed hand) and the second left finger (unexposed hand) before exposure and at 30 and 70 min after the end of both exposure conditions.Analysis of repeated measures of FSBP during local cooling by means of an autoregressive model revealed no significant difference in cold-induced vasoconstriction of the digital arteries between exposure to contact force alone and combined exposure to contact force and vibration. There were no significant changes in the cold response of digital arteries over time in either the right or the left hand after exposure of the right hand to either the contact force alone or the combined contact force and vibration.The results of this experimental study of the influence of prior vibration exposure on the cold test results suggest that in healthy men recent exposure to contact force and moderate levels of hand-transmitted vibration does not affect the response of finger circulation to cold provocation. These findings may be of practical importance for the definition of test conditions in the field, especially the length of time required between the last occupational exposure to tool vibration and the commencement of objective vascular testing.

Objectives: To investigate the prevalence of vascular, neurological and musculoskeletal disorders of the upper limb in a group of female workers performing either mechanical or hand sanding in the furniture industry (n=100) and in a control group of female office workers (n=100). A further aim was to study the possible adverse effects of exposure to a combination of vibration and ergonomic risk factors in female workers. Methods: All female workers underwent a medical interview and a complete physical investigation. The clinical diagnoses of Raynaud’s phenomenon and carpal tunnel syndrome (CTS) were made according to international consensus criteria. Hand-transmitted vibration from orbital sanders was measured according to International Organization for Standardization (ISO) recommendations. Daily vibration exposure was assessed in terms of 8-h energy-equivalent frequency-weighted acceleration [A(8)] according to the European Directive on physical agents. Ergonomic load on the upper limbs was estimated by means of strain index methodology. Results: There was no significant difference in the prevalence of Raynaud’s phenomenon between the furniture workers (4%) and the controls (8%). The prevalence of CTS, peripheral sensorineural disturbances (after exclusion of CTS cases) and upper-limb musculoskeletal complaints was significantly greater in the furniture workers than in the controls. CTS was clinically diagnosed in 19% of the furniture workers and 8% of the controls. A log-binomial regression analysis showed that the occurrence of soft-tissue disorders of the upper limb increased significantly with the increase of both daily vibration exposure and the strain index score. It was estimated that the risk for CTS increased by a factor of 1.30 (95% CI 1.11–1.53) for each unit of increase in A(8) (ms−2), and by 1.09 (95% CI 1.02–1.15) for each unit of increase in the strain index score. Conclusions: Even though the cross-sectional design of this epidemiological study does not allow aetiological considerations, our findings suggest a significant association between occupational use of vibratory tools and soft-tissue disorders in the upper limbs of female workers. Quantitative estimation of vibration exposure and ergonomic stress showed that these physical risk factors seem to contribute in a multiplicative way to the occurrence of chronic nerve and musculoskeletal disorders in female workers operating hand-held vibrating tools in the furniture industry.

To compare the acute response of finger circulation to continuous and intermittent vibration having the same total duration of vibration exposure and the same energy-equivalent acceleration magnitude.Finger blood flow (FBF) was measured in the middle and little fingers of both hands of ten healthy men. Finger skin temperature (FST) was measured in the middle right finger. With a static load of 10 N, the middle finger of the right hand was exposed to 125 Hz at 44 m s(-2) root mean square (r.m.s.) in five conditions: (1). 30 min continuous exposure, (2). two periods of 15 min, separated by a 15 min period with no vibration, (3). four periods of 7.5 min, separated by 7.5 min periods with no vibration, (4). eight periods of 3.75 min, separated by 3.75 min periods with no vibration, (5). 16 periods of 1.88 min, separated by 1.88 min periods with no vibration. All five exposures correspond to an 8 h energy-equivalent frequency-weighted acceleration magnitude of 1.4 m s(-2) r.m.s. according to International Standard ISO 5349-1 (2001). Finger circulation was measured in all four digits before the application of vibration and at fixed intervals during vibration exposure and during a 45 min recovery period.The FST did not change during vibration exposure, whereas all vibration conditions produced significant reductions in FBF of the vibrated finger when compared with the pre-exposure FBF. During vibration exposure, the vibration caused a similar degree of vasoconstriction in the vibrated finger without evidence of cumulative effects during intermittent exposure. After the end of exposure to 30 min of continuous vibration there was a progressive decrease in the FBF, whereas there was no statistically significant reduction following exposure to intermittent vibration.For the vibration stimuli investigated (exposure durations varying from 1.88 min to 30 min, with rest periods varying from 1.88 min to 15 min), the reduction of FBF during exposure was the same for continuous and intermittent vibration. The after effect of vibration was greater following the continuous vibration exposure. Although some evidence from this study is consistent with the notion that intermittent vibration has a less severe effect than continuous vibration, this evidence is not yet conclusive.

The present study aimed to (1) employ the method for evaluation of vibration containing multiple shocks according to ISO/CD 2631-5:2014 (Model 1) and DIN SPEC 45697:2012 in a cohort of 537 professional drivers, (2) deliver the results for a re-analysis of epidemiological data obtained in the VIBRISKS study, (3) clarify the extent to which vibration acceleration and individual variables influence risk values, such as the daily compressive dose S(ed) and the risk factor R, and (4) compare the results with in vivo measurements and those obtained in previous studies with similar models. The risk factor R was influenced by the acceleration, lifetime exposure duration, sitting posture, age at the start of exposure and body mass/body mass index in order of decreasing effect. Age and annual and daily exposure duration had only a marginal effect. The daily compressive dose S(ed) and the risk factor R showed weak linear association with the daily vibration exposure A(8) and the vibration dose value VDV. The study revealed high shear forces in the lumbar spine.In a re-analysis of an epidemiological study of professional drivers, a software tool available with standards DIN SPEC 45697:2012 and ISO/CD 2631–5:2014 Model 1 was used to calculate the risk to the lumbar spine in terms of daily compressive dose S(ed) and risk factor R. The tool was found to be suitable for risk assessment in a large cohort.

Objectives This study investigated the effect of hand elevation on reductions in finger blood flow (FBF) induced by hand-transmitted vibration. Methods Fourteen males attended six sessions on six separate days, with a control sessions and a vibration session (125-Hz vibration at 44 ms 2 r.m.s.) with the right hand supported at each of three elevations: 20 cm below heart level (HL), at HL, and 20 cm above HL. Finger blood flow on the left and right hand was measured every 30 s during each 25-minute session comprised of five periods: (i) no force and no vibration (5 minutes), (ii) 2-N force and no vibration (5 minutes), (iii) 2-N force and vibration (5 minutes), (iv) 2-N force and no vibration (5 minutes), and (v) no force and no vibration (5 minutes). Results Without vibration, FBF decreased with increasing elevation of the hand. During vibration of the right hand, FBF reduced on both hands. With elevation of the right hand, the percentage reduction in FBF due to vibration (relative to FBF on the same finger at the same elevation before exposure to vibration) was similar on the middle and little fingers of both hands. After cessation of vibration, there was delayed return of FBF with all three hand heights. Conclusions Vibration of one hand reduces finger blood flow on both exposed and unexposed hands, with the reduction dependent on the elevation of the hand. The mechanisms responsible for vibration-induced reductions in FBF seem to reduce blood flow as a percentage of the blood flow without vibration. Tasks requiring the elevation of the hands will be associated with lower FBF, and the FBF will be reduced further if there is exposure to hand-transmitted vibration.

Purpose – To investigate the relationships between low back symptoms and alternative measures of external dose and internal spinal dose in professional drivers exposed to whole body vibration (WBV). Methods – The occurrence of low back symptoms were investigated in a cohort of 537 drivers over a two-year follow up period. Low back pain (LBP), individual characteristics, and work-related risk factors were investigated with a structured questionnaire. Exposure to WBV was evaluated by means of measures of external dose (daily vibration exposure in terms of either equivalent continuous acceleration over an eight-hour period (A(8)) or vibration dose value according to the EU Directive on mechanical vibration) and measures of internal lumbar load (daily compressive dose Sed and risk factor R according to ISO/CD 2631-5 2014). Results – In the drivers’ cohort, the cumulative incidence of 12-month low back outcomes was 16.8% for LBP, 9.3% for chronic LBP, and 21.8% for sciatic pain. The measures of internal spinal load were better predictors of the occurrence of low back symptoms than the measures of daily vibration exposure. A two-fold increase in the risk estimates for low back outcomes was found in the upper quartile of the R factor (0.41-0.72 units) compared to the lower one (0.07-0.19 units). Conclusions – In this prospective cohort study, measures of internal spinal dose performed better than measures of daily vibration exposure (external dose) for the prediction of low back outcomes in professional drivers. The ISO boundary values of the risk factor R for low and high probabilities of adverse health effects on the lumbar spine tend to underestimate the health risk in professional drivers.

OBJECTIVES—To investigate the acute effects of the frequency of hand transmitted vibration on finger circulation. A further aim was to investigate whether the frequency weighting assumed in current standards for hand transmitted vibration reflects the haemodynamic changes which occur in the fingers exposed to vibration with different frequencies but with the same frequency weighted acceleration magnitude. METHODS—Finger skin temperature (FST) and finger blood flow (FBF) were measured in the middle fingers of both hands of 10 healthy men. With a static load of 10 N, the right hand was exposed for 15 minutes to the following root mean square (rms) acceleration magnitudes and frequencies of vertical vibration: 5.5 m/s2 at 16 Hz; 11 m/s2 at 31.5 Hz; 22 m/s2 at 63 Hz; 44 m/s2 at 125 Hz; and 88 m/s2 at 250 Hz. These exposures to vibration produce the same frequency weighted acceleration magnitude (5.5 m/s2 rms) according to the frequency weighting included in the international standard ISO 5349. A control condition consisted of exposure to the static load only. Finger circulation was measured before application of the vibration and static load and at fixed intervals during exposure to vibration and a 45 minute recovery period. RESULTS—No significant changes in finger circulation were found with only the static load. The FST did not change significantly during or after acute exposure to vibration. In the vibrated right finger, exposures to vibration with frequencies of 31.5-250 Hz provoked a greater reduction in FBF than did vibration of 16 Hz or the static load only. In the non-vibrated left finger, the FBF measured with vibration at each frequency of 63-250 Hz was significantly lower than that measured with static load only. The reduction in FBF during exposure to vibration with any frequency was stronger in the vibrated finger than in the non-vibrated finger. In both fingers, there was a progressive decrease in FBF after the end of exposure to vibration with frequencies of 31.5-250 Hz. The higher the frequency of vibration, the stronger the decrease in FBF in both fingers during recovery. CONCLUSIONS—Acute exposures to vibration with equal frequency weighted magnitude reduce the FBF in both vibrated and non-vibrated fingers for frequencies between 31.5 and 250 Hz. The extent of digital vasoconstriction after exposure to vibration increases with increasing frequency. The frequency weighting given in current standards tends to overestimate the vasoconstriction associated with acute exposures to vibration frequencies around 16 Hz. Keywords: finger circulation; frequency weighted acceleration magnitude; vibration frequency

The aim of this study is to update the information on the epidemiologic evidence of the adverse health effects of whole-body vibration (WBV) on the spinal system by means of a review of the epidemiologic studies published between 1986 and 1997. In a systematic search, using several databases, of epidemiologic studies of low back pain (LBP) disorders and occupations with exposure to WBV, 45 articles were retrieved. The quality of each study was evaluated according to criteria concerning the assessment of vibration exposure, assessment of health effects, and methodology. The epidemiologic studies reaching an adequate score on each of the above-mentioned criteria were included in the final review. A meta-analysis was also conducted in order to combine the results of independent epidemiologic studies. After applying the selection criteria, 17 articles reporting the occurrence of LBP disorders in 22 WBV-exposed occupational groups reached a sufficient score. The study design was cross-sectional for 13 occupational groups, longitudinal for four groups and of case-control type for one group. Two studies included both cross-sectional and follow-up data on the occurrence of LBP disorders in four occupational groups. The main reasons for the exclusion of studies were insufficient quantitative information on WBV exposure and the lack of control groups. The findings of the selected studies and the results of the meta-analysis of both cross-sectional and cohort studies showed that occupational exposure to WBV is associated with an increased risk for LBP, sciatic pain, and degenerative changes in the spinal system, including lumbar intervertebral disc disorders. Owing to the cross-sectional design of the majority of the reviewed studies, this epidemiologic evidence is not sufficient to outline a clear exposure-response relationship between WBV exposure and LBP disorders. Comparing the epidemiologic studies included in this review with those conducted before 1986, it is concluded that research design and the quality of exposure and health effect data in the field of WBV have improved in the last decade.

This study investigated the relation between vibration exposure, the prevalence of white fingers, and the cold response of digital arterial vessels in workers using vibrating tools.The change in finger systolic blood pressure (FSBP) at 15 and 10 degrees C as the percentage of the pressure at 30 degrees C (FSBP%) was measured in 455 healthy referents and 822 workers exposed to hand-transmitted vibration. Exposure to hand-transmitted vibration was assessed in terms of 8-hour energy-equivalent frequency-weighted acceleration [A(8)] and total operating time with vibrating tools.The prevalence of white fingers was 1.1% for the referents and ranged from 9.0% to 51.6% for the vibration-exposed groups. The estimated mean value of A(8) ranged between 1.6 (referents) and 8.3 (quarry drillers) m/s2. After adjustment for age, smoking, and drinking habits, the FSBP% was significantly lower in the vibration-exposed groups than in the reference group. Groupwise, the FSBP%(10 degrees) was inversely related to the prevalence of white fingers, the estimated A(8), and total operating time. With FSBP%(10 degrees)70% or60% as the lower normal limit, the sensitivity of the cold test varied from 86% to 100%, with a specificity of 90% to 94%, and a positive predictive value of 68% to 74%.FSBP measurement during cold provocation is a useful laboratory test for white fingers. A quantitative relationship between cold-induced digital arterial hyperresponsiveness and occupational exposure to hand-transmitted vibration was suggested.

This paper provides an overview of the exposure-response relationship for the vascular component of the hand-arm vibration syndrome, called vibration-induced white finger (VWF). Over the past two decades, several epidemiological studies have shown a poor agreement between the risk for VWF observed in various occupational groups and that predicted by models included in annexes to International Standard ISO 5349 (ISO 5349:1986, ISO 5349-1:2001). Either overestimation or underestimation of the occurrence of VWF have been reported by investigators. It has been argued that the current ISO frequency-weighting curve for hand-transmitted vibration, which assumes that vibration-induced adverse health effects are inversely related to the frequency of vibration between 16 and 1250 Hz, may be unsuitable for the assessment of VWF. To investigate this issue, a prospective cohort study was carried out to explore the performance of four alternative frequency weightings for hand-transmitted vibration to predict the incidence of VWF in groups of forestry and stone workers. The findings of this study suggested that measures of vibration exposure which give relatively more weight to intermediate and high frequency vibration produced better predictions of the incidence of VWF than that obtained with the frequency weighting currently recommended in International Standard ISO 5349-1:2001.

Objectives This study investigated whether reductions in finger blood flow (FBF) during and after vibration are similarly dependent on the magnitude and duration of vibration. Methods FBF on the left and right hand was measured every minute during, and for 1 hour following, exposure of the right hand to one of three magnitudes of 125-Hz sinusoidal vibration (0, 22, or 88 ms 2 r.m.s.) for one of two durations (7.5 or 15 minutes). Each session comprised five periods: (i) no force and no vibration (5 minutes), (ii) 2-N force and no vibration (5 minutes), (iii) 2-N force and vibration (7.5 or 15 minutes), (iv) 2-N force and no vibration (5 minutes), and (v) no force and no vibration (60 minutes). Results Both magnitudes and durations of vibration reduced FBF in the exposed and unexposed hands, both during and after vibration. With increased magnitude of vibration, there was increased vasoconstriction in all fingers during and after exposure, and longer recovery times after vibration exposure. With increased duration of vibration, there were no changes in vascular responses during exposure but increased vasoconstriction after exposure and prolonged recovery times. With the higher vibration magnitude, the reduction in FBF during exposure was correlated with the time taken to recover after exposure. Conclusions Subjects with greater reduction in blood flow during vibration exposure also have stronger and longer vasoconstriction during subsequent recovery. The correlation between vascular changes during and after vibration exposure suggests similar mechanisms control FBF during and after vibration exposure.

Objectives Finger blood flow is reduced by hand-transmitted vibration but there has been little study of the peripheral vascular response to repetitive mechanical shocks. This study investigated how reductions in finger blood flow depend on shock repetition rate and the peak and rms magnitude of acceleration. Methods Subjects attended seven sessions: six with repetitive mechanical shocks and a control session with no shocks. Each session comprised five successive 5-min periods: (1) no force and no vibration, (2) force and no vibration, (3) force and vibration, (4) force and no vibration and (5) no force and no vibration. During the second– fourth periods, the palm of the right hand applied 2-N force to a vibrator. During the third period, a 125-Hz mechanical shock was applied with one of four repetition rates (1.3, 5.3, 21 or 83.3/s) and one of three acceleration magnitudes (2.5, 5 or 10 ms-2 rms, unweighted). Finger blood flow was measured every 30 s in the middle and little fingers of the right (exposed) hand and the left (unexposed) hand. Results Different repetition rates (1.3–83.3 s-1) and different peak magnitudes (10–88 ms-2 peak) but the same rms acceleration (10 ms-2 rms) caused similar decreases in blood flow in fingers on exposed and unexposed hands. Shocks with a 83.3 s-1 repetition rate, peak magnitude of 10 ms-2 and rms acceleration of 10 ms-2 provoked greater reduction in finger blood flow than shocks with the same peak magnitude but lower repetition rate (21 or 5.3 s-1) and lower rms acceleration (5 or 2.5 ms-2). Conclusions For shocks similar to those based on 125-Hz oscillations with repetition rates between 1.3 and 83.3 s-1, acute reductions in finger blood flow can be predicted from the rms acceleration.

OBJECTIVES--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. METHODS--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. RESULTS--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). CONCLUSION--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.

In a six year follow up study of the handarm vibration syndrome, 62 stoneworkers operating hand held vibrating tools in 10 travertine quarries and mills were first investigated in 1985 and then in 1991. The frequency weighted acceleration of vibration from the rock drills and stone hammers used by the travertine workers exceeded 20 m/s2, indicating a hazardous work activity according to the proposal of the EC directive for physical agents. A clinical examination and a cold provocation test were repeated with the same procedures as those adopted at the time of the first survey. The stoneworkers were divided into groups according to current work state: active stoneworkers who continued to use powered tools during the follow up (n = 21, median exposure time 22 years), and ex-stoneworkers with retirement vibration free intervals of three years (n = 22, median exposure time 27.5 years) and of six years (n = 19, median exposure time 20 years). In the group of active stoneworkers, a 38% onset a new cases of vibration-induced white finger (VWF) was found during the follow up (p < 0.01). Among the retired stoneworkers affected with VWF (n = 24), one recovered from VWF, one showed improvement, 20 remained stationary, and two deteriorated. The ex-stoneworkers experienced no significant change in sensorineural disturbances and a decrease in musculoskeletal symptoms of the upper limbs. At the cold provocation test, the currently active stoneworkers with VWF showed, on a group basis, a delayed finger rewarming time between the two examinations (p = 0.002). An abnormal response to cold provocation persisted in the fingers of the ex-stoneworkers with VWF, even in those reporting subjective improvement. These findings indicate a tendency towards the irreversibility of sensorineural and VWF symptoms in a group of ex-stoneworkers with prolonged exposure to high vibration levels in the past. The increased occurrence of VWF in the active stone workers after a few extra years of vibrating tool usage argues for an urgent implementation of preventive measures in the stone industry.

To investigate prospectively the relation between vibration-induced sensory dysfunction and measures of daily exposure to hand-transmitted vibration (HTV). Thermal perception thresholds for warmth and cold (TPT in °C) and vibrotactile perception thresholds (VPT in dB) at 31.5 and 125 Hz were measured at the fingertips of digit II (for the median nerve) and digit V (for the ulnar nerve) of both hands in 27 male controls and 29 naval engine workers exposed to HTV. In the HTV workers, peripheral sensory function was investigated over a follow-up period of 1–3 years. Vibration exposure was expressed in terms of equivalent frequency-weighted acceleration [A h(eq,T) in ms−2 rms], duration of exposure (T in hours), and frequency-weighted acceleration normalised to a period of 8 h [A(8) in ms−2 rms]. At baseline, the HTV workers showed significantly higher TPT for warmth and lower TPT for cold than the controls, while no differences in the VPTs at both frequencies were observed between the two groups. After adjustment for several confounders, data analysis with the generalised estimating equations method and a transition model showed that the changes over time in the TPTs of the HTV workers were significantly related to all measures of daily vibration exposure [A h(eq,T), T, A(8)]. No significant associations were observed for VPTs at either 31.5 or 125 Hz. The findings of this longitudinal study suggest a significant exposure–response relationship between thermal sensory impairment over time and measures of vibration exposure. The measurement of TPT may be a useful testing method to assess vibration-induced neuropathy at an early stage.

Objectives: To investigate prospectively the relation between vibration-induced white finger (VWF) and measures of cumulative (lifetime) exposure to hand-transmitted vibration (HTV). Methods: Two hundred and forty-nine HTV workers and 138 control men of the same companies participated in a 3-year follow-up study. The diagnosis of VWF (Raynaud’s phenomenon in the controls) was based on the medical history, the administration of colour charts and the results of a cold test. Tool vibration magnitudes were expressed as root-mean-square (r.m.s.) acceleration, frequency-weighted according to international standard ISO 5349-1 and also unweighted over the frequency range 6.3–1250 Hz. From the vibration magnitudes and exposure durations, alternative measures of cumulative vibration dose were calculated for each HTV worker, according to the expression: dose = Σ a i m t i , where a i is the acceleration magnitude on tool i , t i is the lifetime exposure duration (hours) for tool i , and m = 0, 1, 2 or 4. Results: The incidence of VWF varied from 5 to 6% in the HTV workers versus 0 to 1.5% for Raynaud’s phenomenon in the controls. After adjusting for potential confounders, measures of cumulative vibration dose derived from total operating hours and high powers of unweighted acceleration (ie, , with m >1) gave better predictions of the occurrence of VWF than dose measures calculated from frequency-weighted acceleration (ie, ). These findings were observed in the entire sample of HTV workers, in those with no VWF at the initial investigation, and in those with normal cold test results at baseline. Conclusions: This prospective cohort study suggests that measures of cumulative vibration doses constructed from unweighted r.m.s. acceleration perform better for the prediction of VWF than dose measures calculated according to the recommendations of current standards. These findings should contribute to the improvement of the ISO frequency weighting for evaluating the severity of hand-transmitted vibration.

The aim of this study was to investigate the relation between low back pain (LBP) outcomes and measures of daily exposure to whole-body vibration (WBV) in professional drivers. In a study population of 202 male drivers, who were not affected with LBP at the initial survey, LBP in terms of duration, intensity, and disability was investigated over a two-year follow-up period. Vibration measurements were made on representative samples of machines and vehicles. The following measures of daily WBV exposure were obtained: (i) 8-h energy-equivalent frequency-weighted acceleration (highest axis), A(8)(max) in ms(-2) r.m.s.; (ii) A(8)(sum) (root-sum-of-squares) in ms(-2) r.m.s.; (iii) Vibration Dose Value (highest axis), VDV(max) in ms(-1.75); (iv) VDV(sum) (root-sum-of-quads) in ms(-1.75). The cumulative incidence of LBP over the follow-up period was 38.6%. The incidence of high pain intensity and severe disability was 16.8 and 14.4%, respectively. After adjustment for several confounders, VDV(max) or VDV(sum) gave better predictions of LBP outcomes over time than A(8)(max) or A(8)(sum), respectively. Poor predictions were obtained with A(8)(max), which is the currently preferred measure of daily WBV exposure in European countries. In multivariate data analysis, physical work load was a significant predictor of LBP outcomes over the follow-up period. Perceived psychosocial work environment was not associated with LBP.

To investigate prospectively the relation between vibration-induced vascular disorders and measures of daily exposure to hand-transmitted vibration (HTV).Two hundred and forty-nine HTV workers and 138 control men of the same companies participated in a 3-year follow-up study. The diagnosis of vibration induced white finger (VWF) in the HTV workers and that of Raynaud's phenomenon in the controls was based on the medical history, the administration of color charts and the results of a cold test with measurement of finger systolic blood pressures. Vibration magnitudes from the tools were measured as r.m.s acceleration, frequency weighted according to international standard ISO 5349-1, and also unweighted over the frequency range 6.3-1,250 Hz. Daily vibration exposure was expressed in terms of daily exposure duration and frequency-weighted or unweighted r.m.s. acceleration normalized to a reference period of 8 h (Aw(8) or Auw(8), respectively).The incidence of VWF varied from 5 to 6% in the HTV workers versus 0-1.5% for Raynaud's phenomenon in the controls. After adjusting for potential confounders, Auw(8) gave better predictions of the incidence of VWF and the cold response of the digital arteries over time than Aw(8) or daily exposure duration. These findings were observed in the entire sample of HTV workers, in those with no VWF at the initial investigation, and in those with normal cold test results at baseline.The findings of this longitudinal study suggest that a measure of daily vibration exposure calculated from unweighted r.m.s. acceleration over the frequency range 6.3-1,250 Hz performs better for the prediction of vascular disorders in users of vibratory tools than a measure derived from r.m.s. acceleration frequency weighted according to ISO 5349-1. This study provides epidemiological evidence that more weight should be given to intermediate and high-frequency vibration for evaluating the severity of hand-transmitted vibration.

An epidemiologic and clinical study of neck and upper limb musculoskeletal disorders was carried out on 65 vibration-exposed forestry operators using chain-saws and 31 comparable control subjects (maintenance workers) performing manual activity and not exposed to vibration. Upper limb function was evaluated by measuring finger and wrist circumference size, maximal hand grip strength and range of motion manoeuvres in both the controls and the exposed workers. Vibration from two chain-saws was measured, and vibration exposure for each forestry worker was assessed in terms of 4 h energy-equivalent frequency-weighted acceleration according to ISO 5349. Job analysis indicated a slight excess risk of upper extremity cumulative trauma disorders (CTDs) in the forestry operators compared with the control workers. After adjustment for age and body constitution, significantly higher prevalence rates of persistent upper limb pain, muscle-tendon syndromes and carpal tunnel syndrome were observed among the forestry workers than among the controls. In the forestry operators, the occurrence of upper limb musculoskeletal disorders increased with increasing vibration exposure. Upper limb function was found to be impaired in the forestry workers compared with the controls. Vibration exposure was significantly related to increased finger circumference size, diminished muscle force and reduced joint function. Even though it is difficult to establish the relative importance of vibration and ergonomic factors in the aetiology of CTDs, nevertheless the results of this study indicate that musculoskeletal impairment to the upper limbs was more severe in the forestry operators than in the controls who did solely manual work. This finding and the observed dose-effect relationships suggest that vibration stress is an important contributor to the development of musculoskeletal disorders in workers using hand-held vibrating tools.

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.

Two experiments were carried out to investigate the cardiovascular responses of vibration-exposed workers to autonomic stimulation. In the first experiment blood pressures, heart rate and systolic time intervals (STI) were measured during a cold test in 63 vibration-exposed foundry workers and 41 controls. STI, such as total electromechanical systole (QS2I) and left ventricular ejection time index (LVETI), were found to be shorter in the vibration-exposed workers with and without vibration white finger (VWF) than in the controls, both at rest and during cold provocation and recovery (p less than 0.001). A significant inverse relationship between urinary excretion of free catecholamines and the duration of STI was observed under resting conditions (0.001 less than p less than 0.03). In the second experiment, the above mentioned cardiovascular parameters were measured in 11 grinding operators with VWF and 11 controls during a hand grip test, an arithmetic test and an orthostatic test. Finger systolic pressures (FSP) during local cooling to 30, 15 and 10 degrees C were also measured. QS2I and LVETI were more abbreviated in the VWF subjects than in the controls at rest and during both the circulatory stress tests and the recovery periods (0.001 less than p less than 0.05). The reduction in FSP by local cooling from 30 degrees C to 15 and 10 degrees C was greater in the VWF workers than in the controls (p less than 0.001). Significant correlations were observed between the reduction in FSP at 15 and 10 degrees C and the duration of STI during circulatory stress activities (p less than 0.01). A multiple regression analysis pointed out that vibration exposure was the major determinant of STI during circulatory stress, while the importance of age and smoking and drinking habits in predicting STI was negligible. The findings of these studies suggest that the level of cardiac sympathetic activity is increased in VWF workers in comparison with controls. These experimental results are consistent with those of other investigators, indicating that excessive sympathetic reflex activity plays an important role in the pathogenesis of VWF.

To investigate the occurrence of vibration-induced white finger (VWF) and the cold response of digital arteries in a group of forestry workers, most of whom had used anti-vibration (AV) chain saws solely.One hundred and twenty-eight forestry workers underwent initially a medical examination and a standardized cold test with measurement of the change in finger systolic blood pressure after finger cooling from 30 to 10 degrees C (FSBP%(10 degrees )). They were re-examined two or three times over the calendar period 1990-1999. Seventy-one forestry workers were active over the entire follow up period, while 57 retired after 1-8 years from the initial investigation.The initial prevalence and the cumulative incidence of VWF over the follow up period were 26.6 and 11.7%, respectively. In the retired workers, the new cases of VWF occurred before their retirement, that is when they were still active. There were no significant changes in FSBP%(10 degrees ) in the active forestry workers over the follow up period. A significant increased in FSBP%(10 degrees ) (i.e. improvement) was observed in the retired workers at the end of the follow up. FSBP%(10 degrees ) at the cross-sectional investigation was significantly lower in the forestry workers who developed VWF during the follow up than in those who never experienced finger blanching over the study period.The findings of this follow up study suggest that forestry workers with work experience limited to AV chain saws are still at risk of developing VWF. Cessation of vibration exposure in the retired workers was associated with a beneficial effect on the cold response of digital arteries. Cold-induced digital arterial hyperresponsiveness at the initial investigation was a predictive factor for the onset of VWF over time.

To investigate prospectively the relation between vibration-induced white finger (VWF), exposure to hand-trasmitted vibration (HTV) and the cold response of digital arteries in users of vibrating tools. Two-hundred and sixteen HTV workers and 133 control men of the same companies underwent initially a medical examination and a standardised cold test with measurement of the change in finger systolic blood pressure (FSBP) after finger cooling from 30 to 10°C. They were re-examined 1 year later. Tool vibration magnitudes were expressed as frequency-weighted and unweighted r.m.s. accelerations. From the vibration magnitudes and exposure durations, alternative measures of cumulative vibration dose were calculated for each HTV worker, according to the expression: $$ \text{dose} = \sum a_i^m t_i$$ , where a i is the acceleration magnitude on tool i, t i is the lifetime exposure duration for tool i, and m = 0, 1, 2 or 4. Among the HTV workers, the initial prevalence and the 1-year incidence of VWF were 18.1 and 1.7%, respectively. At the first examination, the HTV workers with moderate or severe score for VWF showed a significantly increased cold reaction in the fingers when compared with the controls and the HTV workers with no vascular symptoms. At the follow-up, the controls, the asymptomatic HTV workers, and the prevalent cases of VWF did not show significant changes in the cold response of digital arteries. A deterioration of cold-induced digital vasoconstriction was found in the incident cases of VWF. In the HTV workers, vibration doses with high powers of acceleration (i.e., $$ \text{dose} = \sum a_i^m t_i$$ with m > 1) were major predictors of the vasoconstrictor response to cold at the follow-up examination. The measurement of FSBP after local cooling may be a helpful objective test to monitor prospectively the change in vibration-induced vascular symptoms. The findings of this longitudinal study suggest a dose–effect relationship between cold-induced digital arterial hyperresponsiveness over time and measures of cumulative vibration exposure. In the controls, the cold response of the digital arteries was stable over 1-year follow-up period.

Many millions of workers are exposed to hand‐transmitted vibration from powered tools and are at risk of developing disorders in the fingers, hands, or arms.1,2,3,4 One consequence of prolonged regular exposure to hand‐transmitted vibration is impaired circulation in the fingers, often evident during or following exposure to cold. The symptoms may be first noticed as abnormally cold fingers, but disorder is often diagnosed from reports of attacks of blanching on the distal, middle, or proximal phalanges. The condition is named “vibration‐induced white finger” from the characteristic attacks of blanching that are assumed to be caused by vibration damage, although the attacks are most often provoked by cold.4 The mechanisms involved in this heightened sensitivity to cold are not known, and so there is uncertainty as to the range of symptoms and signs that characterise the disorder. Although it is clear that hand‐transmitted vibration causes vibration‐induced white finger, there is limited evidence as to the characteristics of vibration that are responsible for the injury. To obtain a number indicating the severity of an exposure to vibration (that is, evaluate the vibration), it is necessary to make assumptions as to the importance of the vibration magnitude, the vibration frequency, the vibration direction, the daily exposure duration, and life‐time exposure duration. Various standards have made such assumptions so as to define uniform methods for evaluating the vibration on powered tools. Having defined a measure of vibration severity, it is possible to assess the acceptability of the vibration, in terms of the probability or severity of disorder. In International Standard 5349‐1 (2001), the evaluation is performed using the root‐mean‐square value of the vibration acceleration after it has been frequency‐weighted (using a weighting called Wh), assuming all directions of vibration to be equally important and all locations of contact with the hand to be equally likely to lead to problems.5 The assessment of vibration severity uses the 8‐hour energy equivalent daily exposure (called A(8)) to predict the years of exposure before 10% of persons are likely to develop the first signs of finger blanching. The frequency weighting inherent in current standards and directives did not evolve from epidemiological studies of the conditions causing vibration‐induced white finger, or from experimental studies of the effects of different frequencies of vibration on relevant physiological responses.6,7 The frequency weighting was largely based on a study of how the discomfort produced by hand‐transmitted vibration depends on the frequency of vibration.8 Some recent epidemiological studies suggest that the frequency weighting may not be optimum and that, at least for the vibration on some groups of common tools, the onset of finger blanching may be predicted with greater accuracy without using frequency weighting Wh.9 The frequency weighting has a large effect on the relative importance of vibration on different tools and, consequently, on the risks of injury and the responsibilities of employers. Improved understanding of the importance of vibration frequency therefore has considerable importance. Contact with the vibration on a tool involves the application of force to the fingers. There are tasks that involve the application of a force without exposure to vibration which do not result in the characteristic symptoms of vibration‐induced white finger, so force alone cannot explain the disorder. However, force may be expected to have some direct mechanical effect on circulation within the fingers. Furthermore, force may alter the transmission of vibration into the fingers and hand: increased force will tend to stiffen the tissues, which will change resonance frequencies and tend to increase the transmission of vibration from the area of contact with vibration. Occupational exposures to hand‐transmitted vibration result in symptoms of vibration‐induced white finger after many months, usually years, of regular exposure to vibration. Laboratory studies have found reductions in blood flow during and following exposure of a finger to vibration. The effects are not restricted to the vibrated finger but are also observed in other fingers, including those on a hand not exposed to vibration. Previous experimental studies by the current authors have explored the effects of the magnitude, frequency, and duration of vibration on finger blood flow using controlled contact areas and controlled contact force.10,11,12 The effects of variations in contact force on finger blood flow have not previously been investigated. This study was designed to investigate whether the force applied by a finger affected finger blood flow and whether the effects of force interacted with the acute effects of vibration. Specifically, it was hypothesised that finger blood flow would be affected by the application of force and that the effects of vibration frequency would be dependent on the force applied to the finger.

Objectives: To evaluate process and outcome of a multifaceted occupational health intervention programme on whole-body vibration (WBV) in forklift truck drivers. Methods: An experimental pretest/post-test control group study design. The authors trained occupational health services (OHS) in the experimental group in the use of the programme. OHS in the control group were asked to deliver care as usual. In total, 15 OHS, 32 OHS professionals, 26 companies, and 260 forklift drivers were involved. Post-test measurements were carried out one year after the start of the programme. Results: Baseline data before the start of the programme showed no difference between experimental and control group. Results of the outcome evaluation indicate a slight, although not statistically significant, reduction of WBV exposure in the experimental group (p = 0.06). Process evaluation revealed a positive influence on company policy toward WBV, attitude and intended behaviour of forklift drivers, and a trend towards an increase in knowledge of OHS professionals and company managers. The number of observed control measures with a major impact (levelling of surface and reduction of speed) was rather low. In those cases where control measures had been taken, there was a significant reduction in WBV exposure. This limited effect of the programme might be caused by the short period of follow up and the dropout of participants. The feasibility and the usefulness of the programme within the OHS setting were rated good by the participants. Conclusions: This programme to decrease WBV exposure was partially effective. Significant effects on intermediate objectives were observed. More research on the effectiveness of intervention in the field of WBV is needed.

Aims: To follow up vibration induced white finger (VWF) in a selected group of 73 vibration exposed workers who claimed unsuccessfully for VWF compensation at a first examination. Methods: The VWF claimants were sent to our unit by the National Insurance Institute. The basic compensatory criteria included a positive history of VWF and abnormal cold response of the digital arteries. Following the first unsuccessful examination, over a mean time period of 4.1 (range 1–11) years the National Insurance Institute requested a second examination for all 73 claimants and a third examination for 29. During the follow up period, all subjects continued to work with vibratory tools. Results: There were 14 new cases who reported white finger during the follow up period. In the new VWF cases, finger blanching attacks became visible after about 3.5 years since the first examination. All incident cases of anamnestic VWF showed an abnormal cold response in the digital arteries and obtained compensation according to the basic compensatory criteria. In the entire sample of VWF claimants, there was a discrepancy between positive history of VWF symptoms at medical interview (55%) and abnormal cold provocation outcomes (19%). Digital arterial hyperresponsiveness to cold was associated with both VWF symptoms and the duration of vibration exposure since the first examination. Over the follow up period, a significant increase in the vasoconstrictor response to cold was observed in the vibration exposed workers with no symptoms of finger whiteness. Abnormal cold response was not associated with either age or smoking habit. Conclusions: Cold test measuring finger systolic blood pressure may be considered a useful laboratory method to confirm objectively VWF symptoms and to disclose abnormal cold induced vasoconstrictor response in vibration exposed workers with a negative history of VWF. Medical interview outcomes should be interpreted with caution in medicolegal situations involving VWF claimants.

Objectives: A case–control study was conducted in Verona, Italy, to assess the relationship between occupation, occupational exposures and systemic sclerosis (SSc). Methods: Fifty-five cases (46 female and nine male) and 171 controls were recruited. Interviews provided work histories, including job titles, industry and likelihood of occupational exposure to silica, hand– arm vibration, organic solvents, and other chemicals. Odds ratios (ORs) and 95% confidence intervals (95% CI) were estimated. Results: Female teachers (OR 3.4, 95% CI 1.2–10.1) and textile workers (OR 2.1, 95% CI 1.0–4.6) were at an increased risk of SSc. Compared with those never exposed, age-adjusted and gender-adjusted ORs were 2.3 (95% CI 1.0–5.4) among subjects exposed to organic solvents, 2.5 (95% CI 0.8–8.0) for exposure to selected chemicals, 1.7 (95% CI 0.4–7.6) for exposure to silica, and 1.5 (95% CI 0.5–4.8) for usage of vibrating tools. When data analysis was stratified according to gender, only men showed a significant increase in risk for exposure to solvents and selected chemicals. Conclusions: The findings of this study tend to support the role of organic solvents and certain chemicals in SSc causation. The association with teaching and working in the textile industry suggests that other exposures are involved in the aetiology of SSc among women. However, because of the small number of subjects, particularly in stratified analyses, chance cannot be ruled out as an explanation of some findings of this study.

Aims: To investigate alternative relations between cumulative exposures to hand-transmitted vibration (taking account of vibration magnitude, lifetime exposure duration, and frequency of vibration) and the development of white finger (Raynaud's phenomenon). Methods: Three previous studies have been combined to provide a group of 1557 users of powered vibratory tools in seven occupational subgroups: stone grinders, stone carvers, quarry drillers, dockyard caulkers, dockyard boilermakers, dockyard painters, and forest workers. The estimated total operating duration in hours was thus obtained for each subject, for each tool, and for all tools combined. From the vibration magnitudes and exposure durations, seven alternative measurements of cumulative exposure were calculated for each subject, using expressions of the form: dose = ∑amiti, where ai is the acceleration magnitude on tool i, ti is the lifetime exposure duration for tool i, and m = 0, 1, 2, or 4. Results: For all seven alternative dose measures, an increase in dose was associated with a significant increase in the occurrence of vibration-induced white finger, after adjustment for age and smoking. However, dose measures with high powers of acceleration (m > 1) faired less well than measures in which the weighted or unweighted acceleration, and lifetime exposure duration, were given equal weight (m = 1). Dose determined solely by the lifetime exposure duration (without consideration of the vibration magnitude) gave better predictions than measures with m greater than unity. All measures of dose calculated from the unweighted acceleration gave better predictions than the equivalent dose measures using acceleration frequency-weighted according to current standards. Conclusions: Since the total duration of exposure does not discriminate between exposures accumulated over the day and those accumulated over years, a linear relation between vibration magnitude and exposure duration seems appropriate for predicting the occurrence of vibration-induced white finger. Poorer predictions were obtained when the currently recommended frequency weighting was employed than when accelerations at all frequencies were given equal weight. Findings suggest that improvements are possible to both the frequency weighting and the time dependency used to predict the development of vibration-induced white finger in current standards.

OBJECTIVES—To investigate the acute response of finger circulation to vibration with different combinations of magnitude and duration but with the same "energy equivalent" acceleration magnitude according to current standards for hand transmitted vibration. METHODS—Finger skin temperature (FST) and finger blood flow (FBF) were measured in the middle fingers of both hands of 10 healthy men who had not used hand held vibrating tools regularly. With a static load of 10 N, the right hand was exposed to 125 Hz vibration with the following unweighted root mean square (rms) acceleration magnitudes and durations of exposure: 44 m/s2 for 30 minutes; 62 m/s2 for 15 minutes; 88 m/s2 for 7.5 minutes; 125 m/s2 for 3.75 minutes; and 176 m/s2 for 1.88 minutes. These vibration exposures produce the same 8 hour energy equivalent frequency weighted acceleration magnitude (~1.4 m/s2 rms) according to international standard ISO 5349 (1986). Finger circulation was measured in both the right (vibrated) and the left (non-vibrated) middle fingers before application of the vibration, and at fixed intervals during exposure to vibration and during a 45 minute recovery period. RESULTS—The FST did not change during exposure to vibration, whereas vibration with any combination of acceleration magnitude and duration produced significant percentage reductions in the FBF of the vibrated finger compared with the FBF before exposure (from −40.1% (95% confidence interval (95% CI) −24.3% to −57.2%) to −61.4% (95% CI −45.0% to −77.8%). The reduction in FBF during vibration was stronger in the vibrated finger than in the non-vibrated finger. Across the five experimental conditions, the various vibration stimuli caused a similar degree of vasoconstriction in the vibrated finger during exposure to vibration. There was a progressive decrease in the FBF of both fingers after the end of exposure to vibration with acceleration magnitudes of 44 m/s2 for 30 minutes and 62 m/s2 for 15 minutes. Significant vasoconstrictor after effects were not found in either finger after exposure to any of the other vibration stimuli with greater acceleration magnitudes for shorter durations. CONCLUSIONS—For the range of vibration magnitudes investigated (44 to 176 m/s2 rms unweighted; 5.5 to 22 m/s2 rms when frequency weighted according to ISO 5349), the vasoconstriction during exposure to 125 Hz vibration was independent of vibration magnitude. The after effect of vibration was different for stimuli with the same energy equivalent acceleration, with greater effects after longer durations of exposure. The energy equivalent acceleration therefore failed to predict the acute effects of vibration both during and after exposure to vibration. Both central and local vasoregulatory mechanisms are likely to be involved in the response of finger circulation to acute exposures to 125 Hz vibration. Keywords: finger circulation; energy equivalent acceleration magnitude; vibration frequency; magnitude; and duration

Objectives: To compare the accuracy of several finger systolic blood pressure indices (FSBPIs) for the diagnosis of cold-induced Raynaud's phenomenon in vibration-exposed worker groups with different prevalences of vibration-induced white finger (VWF). Methods: The finger systolic blood pressure (FSBP) in a test finger at 10 °C as a percentage of the pressure at 30 °C, corrected for the change in systolic blood pressure in a reference finger [FSBPI(A)] or the arm [FSBPI(B)], was measured in 455 healthy controls and 874 workers exposed to hand-transmitted vibration (HTV). The following FSBPIs were also calculated: FSBPI(C), as the ratio between FSBP in the test finger at 10 °C and FSBP in the same finger at 30 °C; and FSBPI(D), as the ratio of FSBP to arm systolic blood pressure during finger cooling to 10 °C. The finding of zero systolic blood pressure, FSBP(0), in the cooled finger was taken as an objective sign of Raynaud's attack with complete closure of the digital arteries. Results: On a group basis, all FSBPIs could discriminate between the controls and the HTV workers. In the vibration-exposed worker population, the FSBPIs were significantly lower in the subjects affected with VWF than in those without vasospastic symptoms. The lower normal limits of FSBPIs were derived from the results of the cold test in the controls and were found to vary from 50% to 60%. The FSBPI(A) showed the best sensitivity for the detection of cold-induced digital arterial hyperresponsiveness in both the total sample of HTV workers (sensitivity 87%) and most of the vibration-exposed groups with different prevalence of VWF (sensitivity from 79% to 100%). The results of the receiver operating characteristic analysis suggested a higher diagnostic accuracy of FSBPI(A) when compared with the global performance of the other FSBPIs. In the whole sample of HTV workers, the predictive value of a positive cold test varied from 73% [FSBPI(D)] to 89% [FSBP(0)] and that of a negative test ranged between 89% [FSBP(0)] and 97% [FSBPI(A)]. Conclusions: The findings of this investigation and clinical experience suggest that a discriminating threshold of FSBPI(A)

Objectives: To investigate neural conduction in the upper limbs of symptomatic forestry workers with and without exposure to hand-transmitted vibration. A further aim was to assess the possible relationships between vibration exposure, nerve conduction and finger circulation in the forestry workers who used chain saws. Methods: A detailed neurophysiological investigation was performed on the upper extremities of 20 chain saw workers, 20 forestry operators with heavy manual work but without vibration exposure, and 20 healthy male controls. All subjects were screened to exclude polyneuropathy. Measurements of sensory and motor nerve conduction (velocity and amplitude) were obtained bilaterally from the median, ulnar and radial nerves. To assess peripheral vascular function, the forestry workers underwent a cold test with plethysmographic measurement of finger systolic blood pressure (FSBP). In the chain saw operators, vibration exposure was evaluated according to the International Standard ISO 5349. Indices of daily vibration exposure and lifetime cumulative vibration dose were estimated for each chain saw operator. Results: Sensory nerve conduction in several segments of the median and radial nerves was significantly reduced in the chain saw operators compared with that in the workers doing heavy manual work and the controls. The neurophysiological pattern more frequently observed in the chain saw operators was a multifocal nerve conduction impairment to several neural segments with predominant involvement of sensory rather than motor fibres. Sensory nerve conduction velocities in the hands of the chain saw operators were inversely related to both daily and lifetime cumulative vibration exposures. In the vibration-exposed forestry workers, neither were sensori-motor complaints associated with vascular symptoms (finger whiteness) nor were electrophysiological data related to cold-induced changes in FSBP. Conclusions: Exposure to hand-transmitted vibration, in addition to ergonomic stress factors, can contribute to peripheral nerve disorders occurring in forestry workers who operate chain saws. The findings of this study suggest the existence of an exposure-effect relationship for vibration-induced neuropathy. Different underlying mechanisms are likely to be involved in the pathogenesis of the neurological and vascular components of the hand-arm vibration syndrome.

Objectives Changes in finger circulation were studied during and after acute exposure to increasing magnitudes of hand-transmitted vibration. Methods Finger skin temperature (FST) and finger blood flow (FBF) were measured in the middle fingers of both hands of 10 healthy men. The right hand was exposed for 15 minutes to 125-Hz vibration with acceleration magnitudes of either 5.5, 22, 44, or 62 m/s2 root-mean-square. The measures of finger circulation were taken before the vibration, at fixed intervals during exposure, and during a 45-minute recovery period. Results The FST did not change during vibration exposure, whereas vibration of any magnitude provoked significant reductions in the FBF of the vibrated finger when compared with the preexposure FBF and the contralateral (nonvibrated finger) FBF. Vasoconstrictor aftereffects (ie, during recovery) were observed in both fingers after the end of exposure to vibration magnitudes greater than 22 m/s2 root-mean-square. The higher the vibration magnitude, the stronger the reduction of FBF in either finger during both vibration exposure and the recovery period. This effect was stronger in the vibrated finger than in the nonvibrated finger during both periods. Conclusion Acute exposure to 125-Hz vibration can reduce FBF in both the vibrated and the nonvibrated finger, and the degree of digital vasoconstriction is related to the magnitude of the vibration. The pattern of the hemodynamic changes during and after vibration exposure suggests that complex vasomotor mechanisms are involved in the response of digital vessels to acute vibration.