Hand-arm vibration syndrome in Swedish car mechanics

A follow-up study of vibration-induced injuries in workers exposed to transient and high frequency vibrations

BACKGROUND

In a previous study from 2018, 38 wheel loader assembly workers were examined, showing high exposures to transient and high-frequency vibrations. After the investigation, preventive measures were immediately implemented to reduce the vibration exposure. In 2022, a follow-up study was carried out to examine the effect of these measures.

METHODS

The follow-up study included 35 (27 men and 8 women) of the original 38 workers. They were divided into two groups, 24 workers with ongoing vibration exposure and 11 workers, not vibration exposed since 2018. All participants completed a questionnaire and underwent a thorough examination, including several neurophysiological tests and a comprehensive assessment of musculoskeletal symptoms. The questionnaire responses and on-site vibration level measurements formed the basis for the individual vibration exposure assessment.

RESULTS

In 2018, clear differences were noted between the two groups regarding vibration perception thresholds (VPT), needle test, 2-PD (2-point discrimination), and monofilament test with deviating results in the unexposed group. The difference between the two groups was significantly smaller at the follow-up examination in 2022, where differences remained for VPT and monofilament tests, with deviating test results in the unexposed group. When comparing variable values between 2018 and 2022 within the exposed and unexposed groups, respectively, the unexposed group showed mostly unchanged values, while a deterioration was observed for VPT, needle test and temperature sensitivity test among the exposed workers during follow-up. The prevalence of VWF (Vibration white fingers) was around 30-40% and neuropathy around 75% among exposed workers during follow-up compared to about 60% and 85% respectively, in the unexposed group.

CONCLUSION

The overall categorization of white fingers and neuropathy, according to the Stockholm Workshop Scale, remained largely unchanged in both study groups from 2018 to 2022. The introduction of cost-effective and relatively simple preventive measures may have contributed to this result. Throughout the follow-up period, the number of exposed workers who developed musculoskeletal disorders and newly reported cases of vibration injuries at the factory decreased. Without this preventive program, increased vascular and nerve symptoms would most likely have occurred during follow-up due to continued vibration exposure.

Epidemiological study of multi-site WMSDs in the footwear industry in China

Objectives. This study aimed to identify the prevalence of multi-site work-related musculoskeletal disorders (WMSDs) in Chinese footwear industry workers from 2018 to 2020 and explore the possible influencing factors of WMSDs. Methods. 7106 subjects from 26 large shoe factories in China were investigated using the epidemiological cross-sectional survey method by using the Nordic musculoskeletal questionnaire (NMQ). Results. The total prevalence of WMSDs in the study subjects was 36.8% (2616/7106). Among them, the prevalence of multi-site WMSDs was 26.1% (1858/7106). The proportion of multi-site WMSDs involving two sites was the largest (31.38%). In addition, the results showed that the risk factors of multi-site WMSDs were gender, marital status, long current job experience, poor health, poor working posture, etc. Conclusions. The prevalence of WMSDs was high in the Chinese footwear industry. Based on the results, therefore, it seems necessary to improve work posture, work organization and workenvironment to prevent WMSDs.

Vibration Isolation Properties of Novel Spacer Fabric with Silicone Inlay

Spacer fabrics are good for impact force absorption and have the potential for vibration isolation. Inlay knitting of additional material to the spacer fabrics can give reinforcement to the structure. This study aims to investigate the vibration isolation properties of three-layer sandwich fabrics with silicone inlay. The effect of the presence of the inlay, inlay patterns and materials on the fabric geometry, vibration transmissibility and compression behaviour were evaluated. The results showed that the silicone inlay increases the unevenness of the fabric surface. The fabric using polyamide monofilament as the spacer yarn in the middle layer creates more internal resonance than that using polyester monofilament. Silicone hollow tubes inlay increases the magnitude of damping vibration isolation, whereas inlaid silicone foam tubes have the opposite effect. Spacer fabric with silicone hollow tubes inlaid by tuck stitches has not only high compression stiffness but also becomes dynamic, showing several resonance frequencies within the tested frequency range. The findings show the possibility of the silicone inlaid spacer fabric and provide a reference for developing vibration isolation materials with knitted structure and textiles materials.

Epidemiological study of work-related musculoskeletal disorders and related risk factors among automobile maintenance workers

BACKGROUND

The automotive industry is labor-intensive, and workers are involved in highly repetitive tasks, long hours, and medium to low workloads, resulting in work-related musculoskeletal disorders (WMSDs), which have become a major health concern for workers in this industry. China is a major automotive country with tens of thousands of auto repair workers, but their conditions of WMSDs have been poorly reported.

OBJECTIVE

This work aimed to analyze the current prevalence of WMSDs and their associated risk factors among automobile maintenance workers.

METHODS

A total of 539 respondents from 50 automotive repair and maintenance companies in China were selected to investigate the prevalence of WMSDs via the modified Nordic Musculoskeletal Disorders Questionnaire. Chi-square test and logistic regression models were applied to analyze their associated risk factors.

RESULTS

The total prevalence of WMSDs among 539 workers was 32.8%. The top three body parts for prevalence were the lower back (17.1%), neck (16.3%), and shoulders (14.5%). The highest prevalence of WMSDs was found in the neck (23.6%) and lower back (14.3%) for sheet metal workers and mechanics, respectively, whereas painters had the highest prevalence of WMSDs in the lower back and feet (both at 15.4%). Logistic regression analysis showed that females were at higher risk of WMSDs than males (OR 5.027, [95% CI] [1.278-19.772], p < 0.05). Workers subjected to uncomfortable positions were at increased risk of WMSDs (OR 1.79, [95% CI] [1.333-2.410], p < 0.01).

CONCLUSION

The prevalence of WMSDs is high among automotive maintenance workers, with the highest prevalence in the lower back (17.1%). Uncomfortable working postures and frequent repetitive movements with lower limbs and ankles at work may be important risk factors.

Hand-arm vibration syndrome among harvesting farmers: A cross-sectional study from Pakistan

BACKGROUND

Constant use of hand-held vibratory tools may cause health issues, including hand dysfunction, among farmers. Thus, exposure to these vibratory instruments may cause hand-arm vibration syndrome (HAVS).

OBJECTIVE

The study aimed to measure the prevalence of HAVS and evaluate neurological and vascular symptoms among farmers.

METHODS

This cross-sectional study included 20 villages in Pakistan and used a three-part questionnaire to collect data from farmers exposed to vibration while farming. The study included demographics, the Health Surveillance Questionnaire, and the Stockholm Workshop Classification Scale. SPSS version 22 was used for the data entry and statistical analysis.

RESULTS

433 (43%) participants had musculoskeletal discomfort and 568 (57%) had hand vibration. Raynaud phenomenon was evident in 430 (43%) participants, whereas carpal tunnel syndrome was found in 218 (22%). Tingling was reported by 255 participants (26%), and numbness was reported by 543 (54%). According to the grading of neurological symptoms, 461 (46%) participants were exposed to vibration but did not experience any symptoms, placing them in stage 0. 185 (18.5%) participants with HAVS with infrequent episodes affecting just the tips of one or more fingers were categorized in stage 01 based on grading of vascular symptoms.

CONCLUSION

HAVS are common among harvesting farmers, with the most noticeable vibrations occurring in the shoulder region. Similarly, most farmers had no vascular symptoms, and most were exposed to vibration but had no neurological symptoms.

Evaluation of the design and materials of anti-vibration gloves: Impact on hand dexterity and forearm muscle activity

Many anti-vibration gloves are available in the market but there are lacks of understanding of their effectiveness in facilitating various hand movements. This study addresses the knowledge gap through a wear trial with five types of anti-vibration gloves made of chloroprene rubber and spacer fabric. Surface electromyography of three forearm muscles of 16 male subjects was conducted during gripping, key pinching, woodblock transporting, screw inserting and screw driving tasks. The correlation between the compression properties of the gloves and hand performance was also evaluated. The results show that hand dexterity is inhibited and more muscle activity is needed to carry the woodblocks with the spacer fabric glove without special design features. A thicker glove can reduce the demand of the flexor digitorum superficialis muscle when using an impact driver. A thinner dorsal side and tailored padding can enhance hand dexterity. The findings can be used as a reference for designing anti-vibration gloves.

Assessing mechanical vibration-altered wall shear stress in digital arteries

The aim of this study is to implement and validate a method for assessing acute vibration-altered Wall Shear Stress (WSS) in the proper volar digital artery of the non-exposed left forefinger when subjecting the right hand to mechanical vibration. These changes of WSS may be involved in Vibration White Finger. Hence, an experimental device was set-up to link a vibration shaker and an ultra-high frequency ultrasound scanner. The Womersley-based WSS was computed by picking up the maximum velocity from pulse Wave Doppler measurements and extracting the artery diameter from B-mode images through an in-house image processing technique. The parameters of the former method were optimised on numerical ultrasound phantoms of cylindrical and lifelike arteries. These phantoms were computed with the FIELD II and FOCUS platforms which mimicked our true ultrasound device. The Womersley-based WSS were compared to full Fluid Structure Interaction (FSI) and rigid wall models built from resonance magnetic images of a volunteer-specific forefinger artery. Our FSI model took into account the artery's surrounding tissues. The diameter computing procedure led to a bias of 4%. The Womersley-based WSS resulted in misestimating the FSI model by roughly 10% to 20%. No difference was found between the rigid wall computational model and FSI simulations. Regarding the WSS measured on a group of 20 volunteers, the group-averaged basal value was 3 Pa, while the vibration-altered WSS was reduced to 1 Pa, possibly triggering intimal hyperplasia mechanisms and leading to the arterial stenoses encountered in patients suffering from vibration-induced Raynaud's syndrome.

Theoretical Analysis and Optimization of a Gloved Hand-Arm System

Studies have shown that isolators in the form of antivibration (AV) gloves effectively reduce the transmission of unwanted vibration from vibrating equipment to the human hand. However, as most of these studies are based on experimental or modeling techniques, the level of effectiveness and optimum glove properties for better performance remains unclear. To fill this gap, hand-arm system dynamics with and without gloves are studied analytically in this work. In this work, we use a lumped parameter model of the hand-arm system, with hand-tool interaction modeled as a linear spring-damper system. The resulting governing equations of motion are solved analytically using the method of harmonic balance. Parametric analysis is performed on the biomechanical model of the hand-arm system with and without a glove to identify key design parameters. It is observed that the effect of glove parameters on its performance is not repetitive and changes in the studied different frequency ranges. This observation further motivates us to optimize the glove parameters to minimize the overall transmissibility in different frequency ranges.

Arterial abnormalities in the hands of workers with vibration white fingers - a magnetic resonance angiography case series

Vibration white finger (VWF) is a complication from exposure to hand-arm vibrations. Poor knowledge of the pathophysiology of VWF means that making an accurate prognosis is difficult. Thus, a better understanding of VWF's pathophysiology is of importance.The purpose of this study was to investigate whether there were arterial abnormalities in the hands in patients with VWF and a positive Allen's test, using ultrasound and MRA imaging.This was a case series where arterial abnormalities in the hands were investigated in ten participants with VWF and using prolonged Allen's test (> 5 s). The participants had an average vibration exposure of 22 years and underwent Doppler ultrasound and Magnetic Resonance Angiography (MRA) to check for arterial abnormalities.The participants had VWF classified as 1-3 on the Stockholm workshop scale. Ultrasound and MRA identified vascular abnormalities in all participants, the predominant finding was missing or incomplete superficial arch. Also, stenosis was identified in four participants.This study reveals a high proportion of arterial stenosis and abnormalities in patients with VWF and a prolonged Allen's test.

Vibrotactile sensitivity testing for occupational and disease-induce peripheral neuropathies

The International Standard Organization (ISO) standard 13091-1 describes methods and procedures for performing the vibrotactile perception threshold (VPT) testing to diagnose changes in tactile sensory function associated with occupational exposures. However, the VPT test also has been used in the diagnosis of peripheral neuropathies associated with a number of disorders. This review examines the VPT test, variations in procedures that have been used, as well as disorders and diseases in which this test has been reliable for the detection of sensory changes. Mechanisms potentially underlying the changes in VPTs are also discussed along with procedural and subject/patient factors that may affect the interpretation of test results. Based upon the review of the literature, there are also suggestions for where additional research might improve the administration of this test, depending upon the subject/patient population and interpretation of data.

The hand-arm vibration syndrome associated with the grinding of handheld workpieces in a subtropical environment

OBJECTIVES

To study the characteristics and the factors influencing the occurrence of the Hand-Arm Vibration Syndrome (HAVS) for a population grinding handheld workpieces in a subtropical environment.

METHODS

A total of 803 workers grinding handheld workpieces formed the exposure group and 464 workers not exposed to hand-transmitted vibration (HTV) were recruited as the non-exposed group within the same factory in a subtropical climate area. The basic personal information and clinical symptoms reported were collected by trained physicians using a questionnaire and representative measurements were made of the HTV exposure levels and dose.

RESULTS

The average HTV exposure dose A(8) was measured as 5.3 ± 2.0 m/s2. The proportion of grinders reporting finger blanching was 15.4% while it was 27.5% for finger numbness. Among the non-exposed group, that proportion was 0% and 6.3% respectively. There was a positive association between the vibration exposure duration and the occurrence of finger blanching, finger numbness and finger coldness. Riding a motorcycle to work was also identified as a factor that could contribute to a higher prevalence of finger blanching among the exposed workers, the OR value was found to be 1.75 (1.12, 2.75).

CONCLUSIONS

Workers exposed to vibration in a subtropical area can also present evidence of finger blanching in addition to neurological symptoms. The reported rate of HAVS was positively associated with the exposure duration. And the levels of the duration of exposure relative to symptoms of vibration white finger in a subtropical temperate environment exposed to a high-frequency vibration might be deemphasized by the current ISO weighting. Motorcycle transportation to work was identified as a factor that could influence the development of the HAVS among the exposed population of grinders.

Factors associated with vascular and neurological complications of hand-arm vibration syndrome among tire shop workers in Kelantan, Malaysia

OBJECTIVE

Prolonged exposure to hand-arm vibration (HAV) at the workplace is associated with hand-arm vascular syndrome (HAVS). This study aimed to determine the prevalence and the factors associated with the vascular and neurological complications of HAVS among tire shop workers in Kelantan, Malaysia.

METHODS

A cross-sectional study involving 200 tire shop workers from two districts in Kelantan was conducted. Data were collected at the field using Malay Translated HAVS questionnaire, and hand-arm vibration was measured. Multiple logistic regression analysis was used to determine the associated factors.

RESULTS

The prevalence of vascular and neurological complications of HAVS among the tire shop workers was 12.5% (95% CI: 10.16, 14.84) and 37.0% (95% CI: 30.31, 43.69), respectively. From multiple logistic regression analysis, only A(8) of HAV exposure was significantly associated with the development of vascular complications and A(8) of HAV exposure, age. and body mass index were significantly associated with the development of neurological complications of HAVS.

CONCLUSION

This study has identified that HAVS is a significant problem among workers exposed to HAV in a warm environment. A(8) of HAV exposure is significantly associated with the development of both vascular and neurological complications. Therefore, there is a need for better control of vibration exposure in Malaysia.

Musculoskeletal complications of hand-arm vibration syndrome among tyre shop workers in Kelantan, Malaysia

Objectives. Exposure to hand-arm vibration (HAV) is associated with hand-arm vascular syndrome (HAVS), which is characterized by musculoskeletal complications. However, evidence on this matter has been inconclusive. Therefore, this study aimed to determine and compare the prevalence of musculoskeletal complications of HAVS between a high-exposure (≥5 m·s^-2) group and a low-moderate-exposure (<5 m·s^-2) group and to explore the factors associated with the musculoskeletal complications of HAVS among tyre shop workers in Kelantan, Malaysia. Methods. A cross-sectional study involving 200 tyre shop workers was carried out. HAV was measured by a vibration meter. The workers were divided into two exposure groups - according to their 8-h time-weighted average, A(8), of vibration exposure - and compared. Results. Almost half of the workers reported musculoskeletal complications of the upper limbs and neck. Only the lifetime vibration dose (LVD) was significantly associated with the development of musculoskeletal complications. Conclusion. The high-exposure group had a higher prevalence of musculoskeletal complications. Only the LVD was significantly associated with complications. However, all factors of the work system, such as ergonomics, handgrip force and posture, might contribute to the development of musculoskeletal complications of HAVS and should be included in assessments.

Vibration-induced injuries in workers exposed to transient and high frequency vibrations

Background

The risk of developing vibration white fingers and neurosensory symptoms increases with the duration and intensity of the exposure. The aim of this study was to investigate the risk of developing vibration white fingers (VWF), neurosensory symptoms and musculoskeletal disorders among workers exposed to transient and high frequency vibrations.

Methods

The study included 38 vibration exposed workers from a loader assembly plant in Sweden (30 males and 8 females). All participants answered questionnaires and had a structured interview about work and medical history. A following medical examination included the determination of vibration and temperature perception thresholds and musculoskeletal symptoms in the neck, shoulder, elbow and hands. The individual vibration exposure expressed as A (8)-values and vibration exposure in minutes per day, were obtained from questionnaires answered by the participants.

Results

The prevalence of VWF was 30% among the male workers and 50% among the females. The corresponding prevalence of neurosensory symptoms was 70% among the males and 88% among the females. Musculoskeletal findings were common among the male workers. Dominant symptoms/syndromes were tension neck syndrome, biceps tendinitis, carpal tunnel syndrome and ulnar entrapment in hand/wrist. A total of 32 diagnoses were observed among the male workers and four diagnoses among the female workers. Numbness in fingers and age had the strongest impact on perceived work ability.

Conclusions

ISO 5349-1 considerably underestimates the risks of VWF for this group of workers exposed to transient and high frequency vibrations. It is therefore important to develop a risk assessment standard also covering this frequency range.

Musculoskeletal Disorders and Associated Factors among Vehicle Repair Workers in Hawassa City, Southern Ethiopia

Background

Vehicle repair work is one of the highest risk professions for work-related musculoskeletal disorders. Globally, only a few published studies have examined the prevalence and determinants of work-related musculoskeletal disorders among vehicle repair workers. Related studies in Ethiopia are even fewer. This study aimed to determine the prevalence of self-reported work-related musculoskeletal disorders and associated factors among vehicle repair workers in Hawassa city, South Ethiopia, 2019.

Methods

An institution-based cross-sectional study was conducted among 344 vehicle repair workers in the Hawassa city. The Nordic Musculoskeletal Questionnaire-Extended (NMQ-E) was used to assess work-related musculoskeletal disorders on nine body regions. Descriptive statistics and multivariable analyses were used to characterize the data and identify factors associated with work-related musculoskeletal disorders.

Result

The twelve-month prevalence of work-related musculoskeletal disorders among this working group was 47.7% with 95% CI (42.7-53.2). Jobs continuously requiring repetitive motions (AOR: 4.29, 95% CI (1.78-10.2)), not having professional training (AOR: 2.04, 95% CI (1.09-3.81)), force exertion when using tools (AOR: 2.40, 95% CI (1.24-4.62)), job stress (AOR:4.54, 95% CI (2.44-8.46)), and regularly lifting, pushing, and pulling loads greater than 20 kg (AOR:4.85, 95% CI (2.65-8.87)) were identified as associated factors.

Conclusion

This study showed a 47.7% prevalence of work-related musculoskeletal disorders. Force exertion, repetitive tasks, manual handling of heavy loads, stress, and lack of training were the identified factors. Ergonomic awareness among workers should be increased through training. In addition, owners should investigate methods to reduce or eliminate risk factors leading to musculoskeletal disorders found among these workers. Automation of high-risk tasks should also be investigated.

Raynaud's phenomenon in the occupational context

OBJECTIVE

To review articles that evaluated the prevalence of Raynaud's phenomenon of occupational origin.

METHODS

The search for articles was carried out in the Medline (via PubMed), Embase, Web of Science, Scientific Electronic Library Online (SciELO), and Latin America and Caribbean Health Sciences Literature (Lilacs) databases.

RESULTS

64 articles were obtained from the electronic search; 18 articles met the eligibility criteria. All studies discussed the exposure to vibrations in the upper limbs. In 6 of them, the thermal issue was directly or indirectly addressed. No studies have addressed exposure to vinyl chloride.

CONCLUSIO

In general, a higher prevalence of Raynaud's phenomenon was found among vibratory tool operators compared to non-exposed workers, with an increase in the number of cases the higher the level of vibration and the time of exposure. Cold is a triggering and aggravating factor of the Raynaud phenomenon and seems to play an important role in the emergence of vascular manifestations of the hand-arm vibration syndrome.

Hand-arm Vibration Syndrome in Farmers and its Correlation with Degenerative Triangular Fibrocartilage Complex Injury

Context

Hand-arm vibration syndrome (HAVS) is an occupational disease that affects workers who are exposed to vibrations. Farmers are prone to various musculoskeletal and cumulative trauma disorders. These occur owing to overuse, degeneration, and excess physical efforts along with whole-body vibrations- owing to the use of farming equipment such as tractors and harvesters.

Aims

Aims of the study were to find out the prevalence of various symptoms of HAVS among farmers using tractors, harvesters, etc., and to find out the correlation of triangular fibrocartilage complex (TFCC) injury with HAVS.

Subjects and Methods

A prevalence study was conducted among farmers. Farmers were selected by random sampling method and were asked to fill-up a HAVS surveillance questionnaire. The handgrip strength was recorded with a hand dynamometer. Assessment of carpal tunnel syndrome was done, and correlation of HAVS with TFCC injury was assessed.

Results

Data from 100 farmers was obtained and analyzed. The musculoskeletal symptoms of HAVS, more specifically pain was prevalent (n = 65), followed by sensorineural symptoms (n = 70), and the vascular symptoms were less common (n = 43). HAVS accounts for a prevalence of 64% with 39% of farmers having TFCC injury along with HAVS (P value = <0.0001).

Conclusions

These findings reported in the study provide a better understanding of the impact and extent of HAVS in farmers. There is a significant prevalence of HAVS with mild symptoms of vascular component, mild to moderate symptoms of sensorineural component, and significant involvement of the musculoskeletal component. In addition, TFCC injury is correlated with HAVS.

Prevalence of hand-arm vibration syndrome among tyre shop workers in Kelantan, Malaysia

Background

Prolonged exposure to hand‐arm vibration is associated with a disorder of the vascular, neurological, and musculoskeletal systems of the upper limb known as hand‐arm vibration syndrome (HAVS). Currently, the evidence of HAVS in tropical environments is limited.

Objectives

To determine the prevalence and severity of HAVS among tyre shop workers in Kelantan, Malaysia.

Methods

A cross‐sectional study involving 200 tyre shop workers from two districts in Kelantan was performed. Part one data were collected at the field using questionnaire, and hand‐arm vibration was measured. Part two involved a set of hand clinical examinations. The workers were divided into high (≥5 m s^‐2) and low/moderate (<5 m s^‐2) exposure group according to their 8‐hr time weighted average [A(8)] of vibration exposure. The differences between the two exposure group were then compared.

Results

The prevalence of the vascular, neurological, and musculoskeletal symptoms was 12.5% (95% CI 10.16 to 14.84), 37.0% (95% CI 30.31 to 43.69), and 44.5% (95% CI 37.61 to 51.38) respectively. When divided according to their exposure statuses, there was a significant difference in the prevalence of HAVS for all three components of vascular, neurological, and musculoskeletal (22.68% vs 2.91%, 62.89% vs 12.62% and 50.52% and 38.83%) respectively. All the clinical examinations findings also significantly differed between the two groups with the high exposure group having a higher abnormal result.

Conclusion

Exposure to high A(8) of vibration exposure was associated with a higher prevalence of all three component of HAVS. There is a need for better control of vibration exposure in Malaysia.

Lifetime vibration dose correlates with severity of the neurological component of hand-arm vibration syndrome among tyre shop workers in Kelantan, Malaysia

Introduction. Cumulative lifetime exposure to vibration is believed to contribute to more severe complications of hand-arm vibration syndrome (HAVS). Objectives. To determine prevalence of the neurological component of HAVS and the correlation between lifetime vibration dose (LVD) and neurological severity of HAVS among tyre shop workers in Kelantan. Methods. The cross-sectional study involved 200 tyre shop workers from two districts in Kelantan. Part one data were collected in the field using a questionnaire and hand-arm vibration was measured. Part two involved a set of hand clinical examinations (Purdue pegboard, Semmes-Weinstein monofilament and two-point discrimination tests) carried out for neurological component severity staging. LVD for each worker was calculated from data gathered in part one. For workers who had neurological symptoms, staging according to Stockholm workshop scales was done according to part two data. The strength of correlation between LVD and neurological stages was then determined using Spearman correlation. Results. Prevalence of neurological component was 37%. Spearman correlation between LVD and the neurological stages showed a moderate positive correlation. Conclusion. Cumulative lifetime exposure to hand-transmitted vibration is likely to be related to neurological severity of HAVS and therefore must be considered when assessing workers' exposure to hand-arm vibration.

Vibration characteristics of golf club heads in their handheld grinding process and potential approaches for reducing the vibration exposure

To control vibration-induced white finger among workers performing the fine grinding of golf club heads, the aims of this study are to clarify the major vibration sources in the grinding process, to identify and understand the basic characteristics of the club head vibration, and to propose potential approaches for reducing the vibration exposure. The vibrations on two typical club heads and two belt grinding machines were measured at a workplace. A simulated test station was also constructed and used to help examine some influencing factors of the club head vibration. This study found that the club head vibration was the combination of the vibration transmitted from the grinding machines and that generated in the grinding process. As a result, any factor that affects the machine vibration, the grinding vibration, and/or the dynamic response of the club head can influence the vibration exposure of the fingers or hands holding the club head in the grinding process. The significant influencing factors identified in the study include testing subject, grinding machine, machine operation speed, drive wheel condition, club head model, mechanical constraints imposed on the club head during the grinding, and machine foot pad. These findings suggest that the vibration exposure can be controlled by reducing the grinding machine vibration, changing the workpiece dynamic properties, and mitigating the vibration transmission in its pathway. Many potential methods for the control are proposed and discussed.

RELEVANCE TO INDUSTRY

Vibrations on handheld workpieces can be effectively transmitted to the hands, especially the fingers. As a result, a major component of the hand-arm vibration syndrome - vibration-induced white finger - has been observed among some workers performing the grinding and/or polishing tasks of the handheld workpieces such as golf club heads. The results of this study can be used to develop more effective methods and technologies to control the vibration exposure of these workers. This may help effectively control this occupational disease.

Hand-arm vibration and the risk of vascular and neurological diseases-A systematic review and meta-analysis

Background

Increased occurrence of Raynaud’s phenomenon, neurosensory injury and carpal tunnel syndrome has been reported for more than 100 years in association with work with vibrating machines. The current risk prediction modelling (ISO-5349) for “Raynaud’s phenomenon” is based on a few studies published 70 to 40 years ago. There are no corresponding risk prediction models for neurosensory injury or carpal tunnel syndrome, nor any systematic reviews comprising a statistical synthesis (meta-analysis) of the evidence.

Objectives

Our aim was to provide a systematic review of the literature on the association between Raynaud’s phenomenon, neurosensory injuries and carpal tunnel syndrome and hand-arm vibration (HAV) exposure. Moreover the aim was to estimate the magnitude of such an association using meta-analysis.

Methods

This systematic review covers the scientific literature up to January 2016. The databases used for the literature search were PubMed and Science Direct. We found a total of 4,335 abstracts, which were read and whose validity was assessed according to pre-established criteria. 294 articles were examined in their entirety to determine whether each article met the inclusion criteria. The possible risk of bias was assessed for each article. 52 articles finally met the pre-established criteria for inclusion in the systematic review.

Results

The results show that workers who are exposed to HAV have an increased risk of vascular and neurological diseases compared to non-vibration exposed groups. The crude estimate of the risk increase is approximately 4–5 fold. The estimated effect size (odds ratio) is 6.9 for the studies of Raynaud’s phenomenon when including only the studies judged to have a low risk of bias. The corresponding risk of neurosensory injury is 7.4 and the equivalent of carpal tunnel syndrome is 2.9.

Conclusion

At equal exposures, neurosensory injury occurs with a 3-time factor shorter latency than Raynaud’s phenomenon. Which is why preventive measures should address this vibration health hazard with greater attention.

Tool-specific performance of vibration-reducing gloves for attenuating fingers-transmitted vibration

BACKGROUND

Fingers-transmitted vibration can cause vibration-induced white finger. The effectiveness of vibration-reducing (VR) gloves for reducing hand transmitted vibration to the fingers has not been sufficiently examined.

OBJECTIVE

The objective of this study is to examine tool-specific performance of VR gloves for reducing finger-transmitted vibrations in three orthogonal directions (3D) from powered hand tools.

METHODS

A transfer function method was used to estimate the tool-specific effectiveness of four typical VR gloves. The transfer functions of the VR glove fingers in three directions were either measured in this study or during a previous study using a 3D laser vibrometer. More than seventy vibration spectra of various tools or machines were used in the estimations.

RESULTS

When assessed based on frequency-weighted acceleration, the gloves provided little vibration reduction. In some cases, the gloves amplified the vibration by more than 10%, especially the neoprene glove. However, the neoprene glove did the best when the assessment was based on unweighted acceleration. The neoprene glove was able to reduce the vibration by 10% or more of the unweighted vibration for 27 out of the 79 tools. If the dominant vibration of a tool handle or workpiece was in the shear direction relative to the fingers, as observed in the operation of needle scalers, hammer chisels, and bucking bars, the gloves did not reduce the vibration but increased it.

CONCLUSIONS

This study confirmed that the effectiveness for reducing vibration varied with the gloves and the vibration reduction of each glove depended on tool, vibration direction to the fingers, and finger location. VR gloves, including certified anti-vibration gloves do not provide much vibration reduction when judged based on frequency-weighted acceleration. However, some of the VR gloves can provide more than 10% reduction of the unweighted vibration for some tools or workpieces. Tools and gloves can be matched for better effectiveness for protecting the fingers.

The Efficacy of Anti-vibration Gloves

Anyone seeking to control the risks from vibration transmitted to the hands and arms may contemplate the use of anti-vibration gloves. To make an informed decision about any type of personal protective equipment, it is necessary to have performance data that allow the degree of protection to be estimated. The information provided with an anti-vibration glove may not be easy to understand without some background knowledge of how gloves are tested and does not provide any clear route for estimating likely protection. Some of the factors that influence the potential efficacy of an anti-vibration glove include how risks from hand-arm vibration exposure are assessed, how the standard test for a glove is carried out, the frequency range and direction of the vibration for which protection is sought, how much hand contact force or pressure is applied and the physical limitations due to glove material and construction. This paper reviews some of the background issues that are useful for potential purchasers of anti-vibration gloves. Ultimately, anti-vibration gloves cannot be relied on to provide sufficient and consistent protection to the wearer and before their use is contemplated all other available means of vibration control ought first to be implemented.

An examination of the vibration transmissibility of the hand-arm system in three orthogonal directions

The objective of this study is to enhance the understanding of the vibration transmission in the hand-arm system in three orthogonal directions (X, Y, and Z). For the first time, the transmitted vibrations distributed on the entire hand-arm system exposed in the three orthogonal directions via a 3-D vibration test system were measured using a 3-D laser vibrometer. Seven adult male subjects participated in the experiment. This study confirms that the vibration transmissibility generally decreased with the increase in distance from the hand and it varied with the vibration direction. Specifically, to the upper arm and shoulder, only moderate vibration transmission was measured in the test frequency range (16 to 500 Hz), and virtually no transmission was measured in the frequency range higher than 50 Hz. The resonance vibration on the forearm was primarily in the range of 16-30 Hz with the peak amplitude of approximately 1.5 times of the input vibration amplitude. The major resonance on the dorsal surfaces of the hand and wrist occurred at around 30-40 Hz and, in the Y direction, with peak amplitude of more than 2.5 times of the input amplitude. At higher than 50 Hz, vibration transmission was effectively limited to the hand and fingers. A major finger resonance was observed at around 100 Hz in the X and Y directions and around 200 Hz in the Z direction. In the fingers, the resonance magnitude in the Z direction was generally the lowest, and the resonance magnitude in the Y direction was generally the highest with the resonance amplitude of 3 times the input vibration, which was similar to the transmissibility at the wrist and hand dorsum. The implications of the results are discussed.

RELEVANCE TO INDUSTRY

Prolonged, intensive exposure to hand-transmitted vibration could result in hand-arm vibration syndrome. While the syndrome's precise mechanisms remain unclear, the characterization of the vibration transmissibility of the system in the three orthogonal dimensions performed in this study can help understand the syndrome and help develop improved frequency weightings for assessing the risk of the exposure for developing various components of the syndrome.

Anti-vibration gloves?

For exposure to hand-transmitted vibration (HTV), personal protective equipment is sold in the form of anti-vibration (AV) gloves, but it remains unclear how much these gloves actually reduce vibration exposure or prevent the development of hand-arm vibration syndrome in the workplace. This commentary describes some of the issues that surround the classification of AV gloves, the assessment of their effectiveness and their applicability in the workplace. The available information shows that AV gloves are unreliable as devices for controlling HTV exposures. Other means of vibration control, such as using alternative production techniques, low-vibration machinery, routine preventative maintenance regimes, and controlling exposure durations are far more likely to deliver effective vibration reductions and should be implemented. Furthermore, AV gloves may introduce some adverse effects such as increasing grip force and reducing manual dexterity. Therefore, one should balance the benefits of AV gloves and their potential adverse effects if their use is considered.

Hand-arm vibration syndrome: clinical characteristics, conventional electrophysiology and quantitative sensory testing

OBJECTIVE

Workers exposed to vibrating tools may develop hand-arm vibration syndrome (HAVS). We assessed the somatosensory phenotype using quantitative sensory testing (QST) in comparison to electrophysiology to characterize (1) the most sensitive QST parameter for detecting sensory loss, (2) the correlation of QST and electrophysiology, and (3) the frequency of a carpal tunnel syndrome (CTS) in HAVS.

METHODS

QST, cold provocation tests, fine motor skills, and median nerve neurography were used. QST included thermal and mechanical detection and pain thresholds.

RESULTS

Thirty-two patients were examined (54 ± 11 years, 91% men) at the more affected hand compared to 16 matched controls. Vibration detection threshold was the most sensitive parameter to detect sensory loss that was more pronounced in the sensitivity range of Pacinian (150 Hz, x12) than Meissner's corpuscles (20 Hz, x3). QST (84% abnormal) was more sensitive to detect neural dysfunction than conventional electrophysiology (37% abnormal). Motor (34%) and sensory neurography (25%) were abnormal in HAVS. CTS frequency was not increased (9.4%).

CONCLUSION

Findings are consistent with a mechanically-induced, distally pronounced motor and sensory neuropathy independent of CTS.

SIGNIFICANCE

HAVS involves a neuropathy predominantly affecting large fibers with a sensory damage related to resonance frequencies of vibrating tools.

Evaluation of protective gloves and working techniques for reducing hand-arm vibration exposure in the workplace

OBJECTIVES

Operation of handheld power tools results in exposure to hand-arm vibrations, which over time lead to numerous health complications. The objective of this study was to evaluate protective equipment and working techniques for the reduction of vibration exposure.

METHODS

Vibration transmissions were recorded during different work techniques: with one- and two-handed grip, while wearing protective gloves (standard, air and anti-vibration gloves) and while holding a foam-covered tool handle. The effect was examined by analyzing the reduction of transmitted vibrations at the wrist. The vibration transmission was recorded with a portable device using a triaxial accelerometer.

RESULTS

The results suggest large and significant reductions of vibration with appropriate safety equipment. Reductions of 85.6% were achieved when anti-vibration gloves were used.

CONCLUSIONS

Our results indicated that transmitted vibrations were affected by several factors and could be measured and significantly reduced.

A proposed theory on biodynamic frequency weighting for hand-transmitted vibration exposure

The objective of this study is to propose a theory on the biodynamic frequency weighting for studying hand-transmitted vibration exposures and vibration-induced effects. We hypothesize that the development of a vibration effect is the result of two consecutive but synergistic processes: biodynamic responses to input vibration and biological responses to the biomechanical stimuli resulting from the biodynamic responses. Hence, we further hypothesize that the frequency-dependency (W) of the effect generally includes two components: a biodynamic frequency weighting (W1) and a biological frequency weighting (W2), or W=W1• W2. These hypotheses are consistent with the stress and strain analysis theory and methods widely used in structural dynamics and biomechanics. The factorization may make it easier to study the complex frequency-dependency using different approaches: the biodynamic frequency weighting depends on the passive physical response of the system to vibration, and it can thus be determined by examining the biodynamic response of the system using various engineering methods; on the other hand, the biological frequency weighting depends on the biological mechanisms of the effects, and it can be investigated by studying the psychophysical, physiological, and pathological responses. To help test these hypotheses, this study reviewed and further developed methods to derive the finger biodynamic frequency weighting. As a result, preliminary finger biodynamic frequency weightings are proposed. The implications of the proposed theory and the preliminary biodynamic frequency weightings are also discussed.

Epidemiological evidence for new frequency weightings of hand-transmitted vibration

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.

Hand pain other than carpal tunnel syndrome (CTS): the role of occupational factors

Some occupational factors have been implicated in the development of disorders manifested as hand pain. The associations seem to be well documented in processes such as hand-arm vibration syndrome (HAVS) or writer's cramp. There are contradictory data in the literature about the relationships of trigger finger, De Quervain's tenosynovitis (DQT) and tenosynovitis of the wrist with occupational factors. In this article, we review current knowledge about clinical manifestations, case definition, implicated occupational factors, diagnosis and treatment of the most relevant hand pain disorders that have been associated with occupational factors, excluding carpal tunnel syndrome (CTS).

Can we explain the exposure variability found in hand-arm vibrations when using angle grinders? A round robin laboratory study

OBJECTIVES

To quantify variance components of hand-arm vibration exposure from data collected in a laboratory study of four different angle grinders.

METHODS

Four different angle grinders were sent to seven laboratories for grinding tests by three operators at each laboratory. Vibration in both the throttle and support handles was measured. For one grinder, the experimental set-up was repeated and two measurements were collected for that specific grinder.

RESULTS

At least one-third of the estimated variability is attributable to the wheel and less than one-third to the operator. In repeated experiments, between-occasion, operator and wheel factors explained 4, 29 and 17% of the total variability, respectively.

CONCLUSIONS

Since measured vibrations in the support and throttle handles are significantly differed, measurements should be taken at both locations. Factors influencing vibration variability include the presence/absence of an auto balance unit, wheel and operator, but other factors remain to be elucidated.

How a health and safety management training program may improve the working environment in small- and medium-sized companies

OBJECTIVE

The objective of this controlled intervention study was to investigate the effects of a 2-year training program in health and safety (H&S) management for managers at small- and medium-sized companies.

METHODS

A total of 113 managers of motor vehicle repair garages participated in the training and another 113 garage managers served as a comparison group. The effects were measured using questionnaires sent before and after the intervention to the managers and blue-collar workers at the garages.

RESULTS

The intervention group managers reported significantly greater improvement of their H&S management system than the managers in the comparison group. The results also indicate that the management training positively affected how the workers regarded their supportive working environment.

CONCLUSION

H&S management training may positively affect measures at both garage and individual levels.

Hand-arm vibration syndrome (HAVS) and musculoskeletal symptoms in the neck and the upper limbs in professional drivers of terrain vehicles--a cross sectional study

This study compares the prevalence of symptoms of Hand-arm vibration syndrome (HAVS) and musculoskeletal symptoms in the neck and the upper limbs, between professional drivers of terrain vehicles and a referent group. 769 male professional drivers of forest machines, snowmobiles, snowgroomers and reindeer herders and 296 randomly selected male referents completed a questionnaire about symptoms of HAVS and musculoskeletal symptoms in the neck and the upper limbs. They also gave information about their lifetime exposure duration driving terrain vehicles and their nicotine use. Prevalence odds ratios (POR) were determined and adjusted for age and nicotine use. Results show that there is a relation between exposure to driving terrain vehicles and some of the symptoms of HAVS (POR: 1.2-6.1). Increased odds of musculoskeletal symptoms in neck, shoulders and wrists were also found (POR 1.2-6.4), and it seemed to be related to the cumulative exposure time.

Self-reported asthma was biased in relation to disease severity while reported year of asthma onset was accurate

BACKGROUND AND OBJECTIVES

The aims of the study were to assess the accuracy of self-reported asthma and notified year of asthma onset.

METHODS

The study was performed on a sample of 365 subjects, 18-60 years old, with clinically diagnosed onset of asthma between 1983 and 1986. All subjects were investigated 10 years later, in 1996, with a respiratory questionnaire about the items of asthma and year of onset. The material was analyzed with logistic regression models.

RESULTS

Of the 289 subjects who returned the questionnaire, asthma was reconfirmed in 251 subjects. In a logistic regression model, asthma severity was significantly associated with confirmation of asthma. The median difference between the "true" year of onset and the reported year 10 years later, the recall period was zero, with a 10th to 90th interpercentile range of -2 to 6 years. The recall period was not associated with asthma severity, bronchial hyperresponsiveness, smoking, atopy, or sex.

CONCLUSION

Self-reported asthma is biased in relation to disease severity, meaning that subjects with mild disease were less prone to report their asthma. Reported year of asthma onset among adults seems to be rather accurate, with no obvious dependent misclassifications.

Effects of temperature on vibration-induced damage in nerves and arteries

Vasospastic episodes in hand-arm vibration syndrome are more prevalent among power-tool workers in cold climates. To test whether cold enhances vibration-induced damage in arteries and nerves, tails of Sprague-Dawley rats were vibrated at room temperature (RT) or with tail cooling (<15 degrees C). Cold vibration resulted in a colder tail than either treatment alone. Vibration at both temperatures reduced arterial lumen size. RT vibration generated more vacuoles in arteries than cold vibration. Vibration and cold induced nitration of tyrosine residues in arteries, suggesting free-radical production. Vibration and cold generated similar percentages of myelinated axons with disrupted myelin. Cold with and without vibration caused intraneural edema and dilation of arterioles and venules with blood stasis, whereas vibration alone did not. The similarities, differences, and interactive effects of cold and vibration on nerve and artery damage indicate that temperature is involved mechanistically in the pathophysiology of hand-arm vibration syndrome.

Acute vibration increases alpha2C-adrenergic smooth muscle constriction and alters thermosensitivity of cutaneous arteries

The vascular symptoms of hand-arm vibration syndrome, including cold-induced vasospasm, are in part mediated by increased sensitivity of cutaneous arteries to sympathetic stimulation. The goal of the present study was to use a rat tail model to analyze the effects of vibration on vascular function and alpha-adrenoceptor (AR) responsiveness. Rats were exposed to a single period of vibration (4 h, 125 Hz, constant acceleration 49 m/s2 root mean square). The physical or biodynamic response of the tail demonstrated increased transmissibility or resonance at this frequency, similar to that observed during vibration of human fingers. Morphological analysis demonstrated that vibration did not appear to cause structural injury to vascular cells. In vitro analysis of vascular function demonstrated that constriction to the alpha1-AR agonist phenylephrine was similar in vibrated and control arteries. In contrast, constriction to the alpha2-AR agonist UK14304 was increased in vibrated compared with control arteries, both in endothelium-containing or endothelium-denuded arteries. The alpha2C-AR antagonist MK912 (3 x 10(-10) M) inhibited constriction to UK14304 in vibrated but not control arteries, reversing the vibration-induced increase in alpha2-AR activity. Moderate cooling (to 28 degrees C) increased constriction to the alpha2-AR agonist in control and vibrated arteries, but the magnitude of the amplification was less in vibrated compared with control arteries. Endothelium-dependent relaxation to acetylcholine was similar in control and vibrated arteries. Based on these results, we conclude that a single exposure to vibration caused a persistent increase in alpha2C-AR-mediated vasoconstriction, which may contribute to the pathogenesis of vibration-induced vascular disease.