proceedings _ part ii _ collection of abstracts - 09-30-2015
TRANSCRIPT
1
Table of Contents
Presentations Page
Session I: Health Effects 2
Session II: Tests for and Diagnosis of Health Effects I 11
Session III: Vibration Measurement 26
Session IV: Vibration Reduction and Exposure Control 35
Poster Session 46
Session V: Characterization of Biodynamic Responses 53
Session VI: Computer Modeling and Analysis 66
Session VII: Combined Exposures and Health Effects 81
Session VIII: Risk Assessment and Epidemiology 90
Session IX: Tests for and Diagnosis of Health Effects II 101
Session X: Prevention, Intervention, and Training 108
Index of Authors 117
2
Session I: Health Effects
Chair: Anthony Brammer and Ren Dong
Presenter Title and authors Page
Tohr Nilsson Keynote 1: Hand-arm vibration and the risk of vascular
and neurological diseases - a systematic review and meta-
analysis
Tohr Nilsson, Jens Wahlström, Lage Burström
3
Qingsong Chen The characteristics of vibration-induced white finger
among workers polishing handheld pieces in southern
china
Qingsong Chen, Bin Xiao, Aichu Yang, Hansheng Lin,
Hua Yan, Li Lang, Maosheng Yan, Guiping Chen,
Fansong Zeng, Xuqing Cao
5
Jordan Zimmerman Effects of power tool vibration duration on peripheral
nerve endings
Jordan Zimmerman, James Bain, Magnus Persson, Danny
Riley
7
Manman Gong Effects of occupational hand-transmitted vibration on
cardiovascular system: a meta-analysis
Manman Gong, Xiangrong Xu, Zhiwei Yuan, Rugang
Wang, Sheng Wang, Lihua He
9
3
HAND-ARM VIBRATION AND THE RISK OF VASCULAR AND NEUROLOGICAL
DISEASES - A SYSTEMATIC REVIEW AND META-ANALYSIS
*Tohr Nilsson, Jens Wahlström, Lage Burström
Umeå University, Department of Public Health & Clinical Medicine, Occupational and
Environmental Medicine, SE-901 87, Umeå, Sweden
Introduction
Extensive and prolonged exposure to manual work involving the use of vibrating power
tools can lead to a number of pathological health effects primarily in the peripheral neurological,
vascular and musculoskeletal systems.1,2 The resulting symptom complex is now collectively
summarised and internationally acknowledged as the hand-arm-vibration syndrome or HAVS.
Knowledge of the relation between vibration exposure and the risk of injury is currently primarily
based on narrative summaries of separate scientific reports. Only for the vascular component
("white fingers") of HAVS, has a risk prediction modelling been presented in the annexe to ISO
5349.3 Neurosensory injury, carpal tunnel syndrome and musculoskeletal disorders all lack
separate risk prediction models regarding the hazard of vibration exposure. The following
systematic review of the scientific literature, with an accompanying statistical synthesis (meta-
analysis) attempts to specifically answer the question of how large is the possible risk of
developing an enhanced vasospasm ("Raynaud's phenomenon or" white finger ") or neurosensory
injury in relation to exposure to hand-transmitted vibration.
Methods
This systematic literature review with supporting statistical syntheses (meta-analyses) is
limited to hand-arm vibration exposure and vascular (“Raynaud’s phenomenon”) and nerve injury
(neurosensory disturbance). The review follows the "PRISMA statement" for reporting systematic
reviews and meta-analyses.4 The databases used for interrogation were PubMed and Science
Direct. The literature search covered publications from 1945 until September 31, 2014. The search
strategy used broad search criteria for both exposure and outcome. The eligibility criteria for
studies to be included in the final analysis were: Include measurements or estimates of vibration
exposure, Include the relevant health outcomes, Include only original data (not review), Aim to
study the risk of injury, Be published in English, and Study of health effects on humans. Two
independent reviewers performed the reviews following a pre set protocol for evaluation and
grading of methodological and scientific quality. Studies that reported a risk estimate (odds ratio)
for vascular or nerve injuries in relation to vibration exposure were eligible for the meta-analysis.
The statistical syntheses included random-effect meta-analysis with forest plots, meta-regression
and an analysis of possible influence from publication bias (funnel plots).
We found a total of 4325 abstracts, which all were read and whose validity and eligibility were
assessed according to the pre-established criteria. 293 articles were then examined in their entirety
to determine whether each article met all the inclusion criteria. From the 293 articles 241 were
excluded, which resulted in 52 articles that finally met the pre-established criteria for inclusion in
the systematic review.
4
Results and Discussion
For the outcome Raynaud's phenomenon 41 articles were included in the final analysis. Of
these, 11 were cohort studies, two case-control studies and 28 cross-sectional studies. Studies with
low risk of bias (high quality) were found in all study designs. The articles were published between
1978 and 2013. For the 22 studies that allowed statistical synthesis 18 studies showed a significant
excess risk. The overall risk of vibration exposure for Raynaud’s phenomenon was more than four-
fold compared with unexposed. For the studies with “low risk of bias” the equivalent weighted
risk was almost seven-fold. Meta-regression analysis indicates a dose-response relationship for
Raynaud's phenomenon related to vibration exposure level.
For the outcome neurosensory injury, 33 articles were included of which 7 articles are
unique to the neurosensory injury only. 21 of the articles included also Raynaud's phenomenon
and 2 articles carpal tunnel syndrome. Of the total of 33 articles, 3 were cohort studies, three case-
control studies and 27 cross-sectional studies. 18 studies allowed statistical synthesis. The overall
risk of vibration exposure for neurosensory injury was more than four-fold compared with unexposed. For
the studies with “low risk of bias” the equivalent weighted risk was almost eight-fold. The funnel-
plot analysis indicates that the result might possibly be influenced by publication bias.
This systematic literature review with narrative synthesis and statistical synthesis of the
results consolidates that workers who are exposed to HAV have an increased risk of vascular and
neurological diseases compared to non-exposed groups. Conditioned the assumptions presented
the neurosensory injuries precedes the vascular damage.
References
1. Lawson I, Burke F, McGeoch K, Nilsson T, Proud G. Hand-arm vibration syndrome. In:
Baxter P, Aw T, Cockcroft A, Durrington P, Harrington J, editors. Hunters Diseases of
Occupations. 10th ed. London: Hodder Arnold; 2010. p. 489 -512.
2. Pelmear P, Wasserman D. Hand-Arm vibration: a comprehensive guide for occupational
health professionals. Second ed. Beverly Farms, MA: OEM Press; 1998.
3. ISO 5349-1. Mechanical vibration - Measurement and evaluation of human exposure to hand-
transmitted vibration - Part 1: General guidelines. Draft International Standard. Genevé,
Schweiz: International Organization for Standardization2001 May 1999.
4. Liberati A, Altman DG, Tetzlaff J, Mulrow C, Gotzsche PC, Ioannidis JP, Clarke M,
Devereaux PJ, Kleijnen J, Moher D. The PRISMA statement for reporting systematic reviews
and meta-analyses of studies that evaluate health care interventions: explanation and
elaboration. Journal of clinical epidemiology. 2009 Oct;62(10):e1-34.
5
THE CHARACTERISTICS OF VIBRATION-INDUCED WHITE FINGER AMONG
WORKERS POLISHING HANDHELD PIECES IN SOUTHERN CHINA
*Qingsong Chen, Bin Xiao, Aichu Yang, Hansheng Lin, Hua Yan, Li Lang, Maosheng Yan,
Guiping Chen, Fansong Zeng, Xuqing Cao
Guangdong Province Hospital for Occupational Disease Prevention and Treatment; Guangdong
Provincial Key Laboratory of Occupational Disease Prevention and Treatment, Guangzhou,
Guangdong 510300, China
Correspondence author: [email protected]
Introduction
Hand-transmitted vibration exposure, an important physical occupational hazard, may lead to
hand-arm vibration syndrome (HAVS)1. A typical vascular component of HAVS is vibration-
induced white finger (VWF). It is most frequently reported from the regions or countries with cold
climate. Southern China belongs subtropical region and VWF was rarely reported from such a
region before. However, such an occupational disease was also observed in Southern China recent
years, mostly among workers polishing handheld pieces in some hardware manufacture industries.
This study was designed to investigate the exposure and the characteristics of VWF among these
workers.
Methods
A total of 1,224 polishing workers from golf equipment factories were included in this study.
Of them, 147 VWF cases and 1,077 non-VWF cases (control group) were included. A
questionnaire was conducted regarding general demographic data, habits and customs,
occupational history, health status, etc. This questionnaire inquired about the frequency and extent
of VWF using the Griffin scoring system2. The acceleration of hand-transmitted vibration was
detected by a human vibration detection analyzer (SVANTEK106, Poland)3, and then the
cumulative vibration exposure level (CVEL) was calculated. The Chi square test was used to
analyze the distribution of VWF between the left and right hands. Factors associated with the
occurrence of VWF were screened through building a logistic regression equation with stepwise
backward method.
Results and Discussions
The median of 8 h energy-equivalent frequency-weighted acceleration was 5.54 m/s2 in the
workers. The median (interquartile range) time of vibration-exposure was 80.0 (34.0, 130.0)
months and 29.4% of the workers’ vibration-exposure length were over 10 years. The median
(interquartile range) CVEL was 57.29×103 (25.06×103, 93.82×103). As a result, 12.01% of
polishing workers reported varying degrees of VWF symptoms. In the case group, 137 cases were
recorded in detail with VWF. The incidence of blanching attacks of the thumb, index finger, middle
finger, ring finger, little finger were 21.7%, 88.4%, 58.0%, 17.4%, 8.0% in the left hand,
respectively, and 21.7%, 83.3%, 56.5%, 18.8%, 6.5% in the right hand. There was no significant
difference in the VWF distribution between the left and right hands (P>0.05). According to the
Griffin scoring system, the numbers of 1V, 2Ve, 2Vl, 3V, 4V were 28(20.4%), 32(23.4%),
44(32.1%), 33(24.1%), and 0(0%), respectively. When age, time of vibration-exposure, and
smoking and drinking habit were included into the logistic regression equation, the time of
6
vibration-exposure was the most important factor the occurrence of VWF (OR 1.924, 95% CI
1.613-2.294, P<0.001); the average of the time of vibration exposure was 83.1±58.4 months in the
control group and 119.1±52.1 months in the case group (Z=8.60, P<0.001). With the increase of
time of exposure, the scores of HAVS became higher (Figure 1)
Figure 1: The dose-effect/response relationships
References
1. Heaver C, Goonetilleke KS, Ferguson H, Shiralkar S. Hand-arm vibration syndrome: a
common occupational hazard in industrialized countries. J Hand Surg Eur Vol 2011 2011-06-
01; 36(5):354-63.
2. International Organization for Standardization (2001) ISO5349-1. Mechanical vibration and
shock —Measurement and evaluation of human exposure to hand-transmitted vibration —Part
1: General requirements.
3. Griffin M. Handbook of Human Vibration. London: Academic Press, 1990; 1–988.
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7
EFFECTS OF POWER TOOL VIBRATION DURATION ON PERIPHERAL NERVE
ENDINGS
*Jordan Zimmerman+, James Bain++, Magnus Persson+++, Danny Riley++
+Marquette University Biomedical Engineering
++The Medical College of Wisconsin Cell Biology, Neurobiology & Anatomy
+++Atlas Copco Tools
Introduction
Loss of peripheral nerve endings is seen in the fingers of workers who regularly use percussive, impact power
tools.1 Nerve degeneration is believed to contribute to the finger-numbing phenomenon in Hand Arm Vibration
Syndrome (HAVS). A similar loss of nerve endings has been replicated in a laboratory setting with the rat tail model.2
This model simulates a variety of tools generating shockwaves, including the riveting hammer and bucking bar. HAVS
occurrence has been directly correlated with length of exposure, as 50% of riveters with 10 or more years of exposure
exhibit HAVS.3 Although we have previously observed peripheral nerve damage after a single 12 min bout of
vibration, 12 minutes of exposure is considered a heavy workday. A common workday consists of 1 min/day
cumulative use of riveting tools.3 The present study used the rat tail model to examine the effects of 1, 6, and 12 min
single bouts of vibration on peripheral nerve endings.
Methods
Twelve female, 8 week-old Sprague Dawley rats were used in this study. 1, 6, and 12 minute bouts of
vibration exposure were delivered using the rat-tail model (n=3/time point). The animal protocol was approved by the
MCW IACUC. The riveting hammer setup of the rat-tail model was conserved, but a piezoelectric sensor was used as
a means of data collection rather than a laser vibrometer.3 MacroFiberComposite M8503-P2 piezoelectric sensors are
able to produce a voltage when experiencing a load. A single sensor was taped to the dorsum of the rat tail, and later
taped to the surface of the riveting hammer platform, in absence of the rat tail. From these data, the transmissibility
was calculated for 10 dominant frequencies observed in the riveting hammer signal. The frequencies of interest ranged
from 36 Hz to 16.3 kHz. Therefore, a sampling frequency of 75 kHz was chosen to abide by the Nyquist rate. The
animals recovered for 3.5 days to permit nerve injury to equilibrate before euthanasia and tissue acquisition. Cross-
sections were cut from decalcified tail segments 11 and 12 from non-vibrated control and vibrated test animals.
Quantitation of lanceolate mechanosensory nerve endings was conducted on PGP9.5 antibody-immunostained
nerves.2,5
Results and Discussion
The number of nerve ending processes per
lanceolate receptor complex was similar in the sham and
1 min vibrated rats (Fig. 1). The number of nerve endings
was significantly reduced for 12 min vibration, indicating
vibration-induced injury (Figs. 1, 2). Increasing duration
of vibration is more damaging based on the progressive
reduction in nerve endings.
Fig 1: Plot of the average number of nerve ending
processes per lanceolate mechanoreceptor (mean ± sem).
8
Fig 2: The nerve ending processes of lanceolate mechanoreceptors
enwrap 3 hairs in the tail skin of a sham, non-vibrated rat (top panel).
The 12 min-vibrated rat exhibits a loss of integrity and reduced
number of nerve endings on 3 hairs (lower panel). Magnification bar
in top panel equals 63 µm.
Transmissibility was >1 for frequencies ≤ 3.9 kHz, whereas transmissibility was <1 for the 3 higher
frequencies (Table 1). Vibration magnitudes at 12.4 and 16.3 kHz were at least two orders of magnitude greater than
those at the other frequencies (Table 1). Larger transmissibility values (>1) may cause nerve damage to the tail through
properties of resonance, while lower transmissibility values (<1) may cause nerve damage via energy absorption,
presumably as high frequency shockwaves.
Table 1: The dominant frequencies and peak magnitudes are
listed for the vibration platform. Transmissibility at each
frequency represents the ratio of peak magnitude on the tail
divided by the magnitude on the vibration platform.
References
1. Takeuchi, T., Futatsuka, M., Imanishi, H., & Yamada, S. (1986). Pathological changes observed in the finger
biopsy of patients with vibration-induced white finger. Scandinavian Journal of Work, Environment and Health,
12(4), 280–283.
2. Raju, S. G., Rogness, O., Persson, M., Bain, J., & Riley, D. (2011). Vibration from a riveting hammer causes
severe nerve damage in the rat tail model. Muscle and Nerve, 44 (November), 795–804.
3. Dandanell, R., & Engstrom, K. (1986). Vibration from riveting tools in the frequency range 6 Hz - 10MHz and
Raynaud’s phenomenon. Scand J Work Environ Health 12, 338-342.
4. Xu XS, Riley DA, Persson M, Welcome DE, Krajnak K, Wu JZ, Govinda Raju SR and Dong RG. (2011)
Evaluation of anti-vibration effectiveness of glove materials using an animal model. Biomed Mater Eng 21:193-
211.
5. Li, L. and Ginty, DD. (2014) The structure and organization of lanceolate mechanosensory complexes at mouse
hair follicles. eLife 2014;3:e01901:1-24.
9
EFFECTS OF OCCUPATIONAL HAND-TRANSMITTED VIBRATION ON
CARDIOVASCULAR SYSTEM: A META-ANALYSIS
*Manman Gong, Xiangrong Xu, Zhiwei Yuan, Rugang Wang, Sheng Wang, Lihua He
Peking University Health Science Center, Beijing, China
Corresponding author: HE Li-hua ([email protected])
Introduction
Many workers in several industrial sectors, especially in manufacturing and construction, are
exposed to Hand-transmitted Vibration (HTV), also known as Hand-arm Vibration or Segmental Vibration.
In the last few decades, the damage to their cardiovascular system caused by HTV has raised concern from
scholars both at home and abroad. However, conclusions drawn from different researches vary a lot with
large errors because of limitations of time, region, population and other factors. To improve statistical power
so as to ensure the reliability, this essay has conducted Meta-analyses based on large amounts of domestic
and overseas research findings about the effects of HTV on workers’ cardiovascular system. This essay is
aimed to obtain a more convincing conclusion which will provide fundamental data for precaution and
diagnosing.
Methods
Chinese literature retrieval database included CNKI, WanFang Data, VIP, and Sinomed. English
literature retrieval database included PubMed, EMBASE, The Cochrane Library, which were made before
June 2013. The Chinese key searching terms were divided into two groups. The first one included 手传振
动,手臂振动,局部振动 and the second group included: 白指,雷诺现象,手臂振动病,局部振动病,手臂振
动综合征,高血压,血压升高,心率,心电图,心血管. The English searching terms also had two groups. The
first group included: hand-transmitted vibration, hand-arm vibration, segmental vibration, and the second
group had white finger, Raynaud's phenomenon, hand-arm vibration syndrome, hand-arm vibration disease,
finger dermal temperature, hypertension, blood pressure, heart rate, electrocardiogram, and cardiovascular
system. Terms in each group were combined by “or”, while each group was combined by “and”.
Study type were all the cross-sectional surveys and retrospective cohort studies, including both
Chinese and English literatures, which describing the effects of HTV on cardiovascular system of workers.
And exposure group involved workers who exposed to HTV. Control group was consisted of non-exposed
workers, which was comparable with exposure group in age, working years, gender and other aspects.
Besides, reviews, news, and other non-original research were supposed to be excluded as well as repetitive
reports, irrelevant reports, brief reports. We should also exclude animal and cell experiments, non-original
data, non-occupational exposure literatures and etc.
This essay adapted the quality evaluation criteria recommended by Agency for Healthcare Research
and Quality. The researchers were well trained and the criteria were unified. All the tasks were conducted
respectively by every two researchers in parallel.
Software NoteExpress2 was used to manage literatures from search results. The literature excerpts
table was established in Excel 2007. RevMan5.2 was used to conduct pooled analysis and fractional analysis
based on heterogeneity selection model. The significance level was set to 0.05.
Results
This essay included fifty-five literatures. The quality evaluation criteria recommended by AHRQ
includes eleven items, which are supposed to be marked with “Yes”, “No” or “Uncertain”. The more items
with the mark “Yes”, the higher are the quality of literatures. Evaluated 51 pieces of literatures included, it
turned out that the number of “Yes” of each literature was more than five, which means the quality was
10
good.
HTV could lead to hand-arm vibration syndrome (HAVS), which is a serious systemic disease
mainly with peripheral circulation disturbance. Individuals with HAVS typically showed vibration-induced
white finger as well as changes of blood pressure and ECG. Meta-analysis was carried out which based on
the prevalence data provided by all the research that has been done. Fixed effect model was adapted to
combine all the studies. The difference of prevalence of HAVS, VWF (Raynaud’s phenomenon of control
group) and hypertension between exposed group and control group was statistically significant (p<0.05).
The Meta-Analysis of effects of HTV on workers’ ECG showed that the difference of prevalence of sinus
arrhythmia, sinus bradycardia, conduction block, ST-T change was statistically significant (p<0.05), while
the difference of prevalence of premature beat and left ventricular hypertrophy had non statistical
significance (p≥0.05). According to the grouping analysis based on working years, the risk of suffering
from VWF increased with working years, but not obvious. And the prevalence rates were comparatively
higher in 3years~ group and 12years~ group. Also, the result indicated that no significant publication bias
was found in the Meta-Analysis and the significance to combined effects could be ignored.
Discussion
Population survey indicated long-term exposure to HTV would have an effect on cardiovascular
system with different symptoms. Before this essay, there have not been such studies that adapt Meta-
Analysis into the studies on effects of HTV on workers’ health. And we collect, select and evaluate all the
relevant studies to give comprehensive assessment about effects of occupational hand-transmitted vibration
on cardiovascular system.
Among all the indicators, the effect size of HAVS (RR=15.57) was the highest, while there was no
specific treatment currently. The patients would suffer from visible deformation joints and atrophy of hand
muscles, which would bring great pain and inconvenience to their daily work and life. Therefore, it is
indispensable to take effective measures to protect workers. The prevalence rates of VWF and hypertension
of exposed group were 2.86 and 2.92 times respectively as much as these of control group. When it came
to the effects of HTV on ECGs of workers, it was mainly shown that ST-T change, conduction block, sinus
bradycardia and sinus arrhythmia, while the difference of the prevalence rates of premature beat and left
ventricular hypertrophy had non statistical significance.
The prevalence of VWF was relevant to individual factors, vibration intensity, duration,
environment temperature and other factors. Exposed workers may have complex and various working
environment, change their occupations frequently, and use different kinds of vibration tools with different
intensity and duration which will affect the prevalence of VMF. Most of the current studies were carried
out among male workers. So grouping analysis cannot be conducted according to onset age or gender.
Compared with other occupational physical factors such as noise, the studies on effects of HTV
exposure on human body were quite few. So it is urgent to carry out comprehensive and in-depth studies.
In addition, the bias brought by cohort study cannot be completely avoided. However this essay collected
relevant literatures as far as possible through various methods and strived to control all kinds of bias. The
study results will provide fundamental data for precaution and diagnosis, as well as establishment of health
regulations.
11
Session II: Tests for and Diagnosis of Health Effects I
Chairs: Noriaki Harada and Xueyuan Xu
Presenter Title and authors Page
Anthony J. Brammer Neuronal origin of vibrotactile perception thresholds at
the fingertips
Anthony J. Brammer
12
Mahbub Hossain Vibration-induced peripheral neuropathy: involvement of
fingers and diagnostic performance of vibrotactile
perception measurement revisited
Mahbub Hossain, Tatsuya Ishitake, Youichi Kurozawa,
Tsunehiko Takahashi, Norikuni Toibana, Ryosuke Hase,
Yoshinao Kawano, Noriaki Harada
14
Lars Gerhardsson Test-retest reliability of neurophysiological tests of hand-
arm vibration syndrome in vibration exposed workers and
unexposed referents
Lars Gerhardsson, Lennart Gillstrom, Mats Hagberg
16
Ron House Infrared thermography for the diagnosis of vascular
abnormalites in the hands and feet in hand-arm vibration
syndrome
R House, L Holness, I Taraschuk
18
Sandy P. Shiralkar Sole photographic evidence can be deceiving as a proof
of diagnosis in the medicolegal compensation claim to
confirm hand-arm vibration syndrome
Siobhan C. McKay, Sandy P. Shiralkar
20
Ying Ye Finger rewarming time in healthy men and women:
effects of room temperature and gender
Ying Ye, Michael J Griffin
22
Qingsong Chen Finger skin temperature during cold water immersion test
for diagnosing hand-arm vibration syndrome in different
climates in china
Bin Xiao, Danying Zhang, Aichu Yang, Guiping Chen,
Li Lang, Hansheng Lin, Xuqing Cao, Guoyong Xu,
Qingsong Chen
24
12
NEURONAL ORIGIN OF VIBROTACTILE PERCEPTION THRESHOLDS
AT THE FINGERTIPS
*Anthony J. Brammer
Department of Medicine, University of Connecticut Health, Farmington, CT 06030, USA,
and Envir-O-Health Solutions, Ottawa, ON KIJ8W9, Canada
Introduction
Impaired tactile perception is a sensorineural symptom of the hand-arm vibration syndrome that is
associated with pathological neuronal deficits in the hands.1 Considerable progress has been made during
the last thirty years in understanding the neuronal responses mediating the sense of touch and their
relationships to vibrotactile perception.2-5 A combination of physiological and psychophysical studies on
humans has confirmed that tactile perception at the fingertips depends on activity in four populations of
specialized nerve endings. These are commonly described by their responses to skin indentation as: SAI -
slowly adapting type I, SAII - slowly adapting type II, FAI - fast adapting type I, and FAII - fast adapting
type II mechanoreceptors. The SAI mechanoreceptors are primarily responsible for resolving large scale
features of a surface, such as ridges or edges, while the FAI and FAII populations are primarily responsible
for resolving small scale features (e.g., surface texture), and detecting the movement of objects in contact
with the skin. SAII mechanoreceptors signal skin stretch, and their role in vibrotactile perception, if any,
remains unclear.
An early observation was the similarity between the vibrotactile perception thresholds (VPTs)
recorded when the fingertips were stimulated by sinusoidal vibration at selected frequencies and neuronal
activity in the most sensitive mechanoreceptor units at these frequencies.4,5 The purpose of this paper is to
extend the analysis of neuronal activity and VPTs to derive a numerical estimate for the onset of sustained
neuronal activity at the fingertips, and compare this to the results of a psychophysical study designed to
identify different channels of vibrotactile perception using apparatus compatible with ISO 13091-1.6,7
Methods The nerve fiber action potentials generated by single mechanoreceptor units at the fingertips of
alert human subjects in response to sinusoidal vibration have been reported by Johansson and co-workers.3
From these data, contours expressing the vibration acceleration at which the mean single-unit response was
one action potential per two stimulus cycles have been constructed as a function of frequency. An estimate
for the onset of sustained neuronal activity in different mechanoreceptor populations is then obtained by
adjusting the FAI and SAI single-unit contours by the mean population densities of these receptors relative
to that of the FAII receptors at the fingertips, using the results of Vallbo and Johannson.2 No adjustment is
made to the FAII single-unit contour.
In addition, a psychophysical experiment has been performed in which human subjects are
presented a pure-tone conditioning vibration stimulus at 31.5 Hz or 200 Hz, at 20 dB above the perception
threshold (i.e., 20 dB sensation level, SL), while VPTs are determined successively at 4 and 200 Hz, or at
4 and 31.5 Hz, during the 31.5 or 200 Hz conditioning stimulus, respectively. The apparatus complied with
method A of ISO 13091-1,6 and was conducted with the palm and fingers fully supported and facing
upwards, a 3 mm diameter, flat-ended circular stimulator, and a contact force of 0.04 N. Subjects gave their
informed consent to participate in the study, which had received ethics committee approval.
Results and Discussion
The estimate for the onset of sustained neuronal activity, which is taken here to correspond to the
onset of sensation at a given frequency, is shown in Figure 1.
13
Conditioning
Stimulus
Mean Threshold Shift
± Standard Deviation (dB)
Freq.
(Hz)
SL
(dB)
4 Hz 31.5 Hz 200 Hz
31.5
20 -1.6
±2.9
NA 1.4
±6.0
200
20 -0.8
±1.8
0.9
±2.5
NA
Table1: Mean threshold shift (± standard deviation)
Figure 1: Neuronal estimate for the onset of sensation in response to a 20 dB SL pure-tone conditioning
for different mechanoreceptor populations vibration stimulus (NA- not applicable)
The contours suggest that at stimulus frequencies from 3 to 5 Hz, the most sensitive
mechanoreceptor population will be the SAI receptors, which consequently appear most likely to mediate
the VPTs at these frequencies with suitably defined conditions of stimulation. Similarly, at the other
frequencies prescribed by ISO 13091-1, the FAIs may be expected to mediate the VPTs from 20 to 31.5
Hz, and the FAIIs from 100 to 160 Hz.
The results of the psychophysical experiment are shown in Table 1. The mean threshold shifts at 4
and 200 Hz, or 4 and 31.5 Hz, are found to be insignificantly different from zero for each conditioning
stimulus. Now Verrillo and Gescheider have shown a conditioning stimulus elevates the VPT equally at all
frequencies mediated by that psychophysical channel.7 Hence, the results of this experiment confirm that
VPTs at 4, 31.5 and 200 Hz when stimulated in the manner specified by ISO 13091-1 are mediated by
different mechanoreceptor populations, as would be expected from the neuronal estimates for the onset of
sensation in Figure 1. Confirmation of the existence of different psychophysical channels mediating VPTs
at these frequencies is also provided by masking,8 and temporary threshold shift,5 paradigms. Reference
again to Figure 1 reveals another property of mechanoreceptor populations that has been confirmed by
psychophysical studies,8 namely with more intense stimulation at a given frequency, a second (or third)
“threshold” mediated by a different receptor population can be obtained.
References 1. Takeuchi, T., Futatsuka, M., Imanishi, H., and Yamada, S. (1986). Pathological changes observed in the finger
biopsy of patients with vibration-induced white finger. Scand. J. Work Environ. Health, 12, 280-283. 2. Vallbo Å.B., and Johannson, R.S. (1984). Properties of cutaneous mechanoreceptors in the human hand related
to touch sensation. Human Neurobiol., 3, 3-14. 3. Johannson, R.S., Landström, U., and Lundström, R. (1982). Responses of mechanoreceptive afferent units in the
glabrous skin in the human hand to sinusoidal skin displacements. Brain Res., 244, 17-25. 4. Löfvenberg, J., and Johansson, R.S. (1984). Regional differences and interindividual variability in sensitivity to
vibration in the glabrous skin of the human hand. Brain Res., 301, 65-72. 5. Lundström, R., and Johannson, R.S. (1986). Acute impairment of the sensitivity of skin mechanoreceptive units
caused by vibration exposure of the hand. Ergonomics, 29, 687-698. 6. ISO 19091-1 (2001). Mechanical Vibration - Vibrotactile perception thresholds for the assessment of nerve
dysfunction - Part 1: Methods of measurement at the fingertips. International Organization for Standardization, Geneva.
7. Verrillo, R.T., and Gescheider, G.A. (1972). Effect of prior stimulation on vibrotactile thresholds. Sensory Processes, 1, 292-300.
8. Gescheider, G.A., Bolanowski, S.J., Pope, J.V., and Verrillo, R.T. (2002). A four-channel analysis of the tactile
sensitivity of the fingertip: Frequency selectivity, spatial summation, and temporal summation. Somatosensory
Motor Res., 19, 114-124.
14
VIBRATION-INDUCED PERIPHERAL NEUROPATHY: INVOLVEMENT OF
FINGERS AND DIAGNOSTIC PERFORMANCE OF VIBROTACTILE PERCEPTION
MEASUREMENT REVISITED
*Mahbub Hossain+, Tatsuya Ishitake++, Youichi Kurozawa+++, Tsunehiko Takahashi++++, Norikuni
Toibana+++++, Ryosuke Hase+, Yoshinao Kawano+, Noriaki Harada+
+Department of Hygiene, Yamaguchi University Graduate School of Medicine, Ube, Japan ++Department of Environmental Medicine, Kurume University School of Medicine, Kurume, Japan
+++Department of Social Medicine, Faculty of Medicine, Tottori University, Yonago, Japan ++++Kaetsu Hospital, Niigata, Japan
+++++Kensei-Ishii Clinic, Tokushima Japan
Introduction
Peripheral neuropathy in hand-arm vibration syndrome (HAVS) may involve multiple sites of the
upper extremity. Vascular and neurological components of HAVS appear to occur and progress
independently1; the apparent sparing of thumb in vascular component of HAVS may not be so in
neurological component of it. However, in published literature, there is a lack of studies that compared the
involvement of the thumb and other fingers affected by peripheral neuropathy among patients with HAVS.
Also, the diagnostic significance of such involvement of the thumb in HAVS is not clear. Therefore, the
purpose of this study was to investigate this issue and compare the diagnostic value of measurement of
vibrotactile perception threshold (VPT) at the thumb and other fingers in diagnosing peripheral neuropathy
in HAVS.
Methods
A total of 61 HAVS patients and 62 control subjects from eastern and western regions of Japan
underwent a personal interview and various tests on two different days. Vibrotactile perception threshold
(VPT) was measured at every fingertip of the test hand (worst-affected hand for the patients and dominant
hand for the controls) at three frequencies‒ 4 Hz, 31.5 Hz and 125 Hz, by a commercial vibrometer (HVLab
Tactile Vibrometer, University Southampton, UK), in accordance with the ISO 13091-12. VPT data from
36 patients and 37 control subjects could be included in the final analysis. The values of the VPT data were
transformed to dB (relative 10−6 ms−2). The group differences between two-related samples were analyzed
using Wilcoxon signed-ranks test with Bonferroni corrections for multiple comparisons when appropriate.
The diagnostic performance of the test was evaluated with the receiver operating characteristic (ROC) curve
analysis and areas under the ROC curve (AUC) for each finger at each test frequency, and the following
were calculated: sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV),
positive likelihood ratio (LR+), and negative likelihood ratio (LR−). Statistical analysis was performed with
2 statistical softwares: Medcalc version 10.0.2 (MedCalc Software, Mariakerke, Belgium) and IBM SPSS
Statistics for Windows, version 22.0 (IBM Corp, Armonk, NY). Statistical significance was considered at
a two-sided P<0.05.
Results and Discussions
Compared to age-matched control subjects, as in all other fingers, VPT of the thumb was
significantly higher among the patients at all test frequencies (P<0.05 to 0.005; Wilcoxon signed-ranks
test); the differences were larger at 31.5 Hz and 125 Hz. Overall, the VPT at all fingers increased as the test
frequency increased. Across different test frequencies, at a specificity of 80%, the values obtained for the
15
thumb ranged between 50.0% to 83.3% for sensitivity, 72.0% to 81.1% for PV+, 62.5% to 83.3% for PV-,
2.6 to 4.4 for LR+, and 0.6 to 0.2 for LR- ; the values for the other fingers ranged between 41.7 to 88.9%,
68.2% to 82.9%, 58.8% to 88.2%, 2.2 to 5.0, and 0.1 to 0.7 for sensitivity, PV+, PV-, LR+, and LR-,
respectively (table 1). Under each test frequency, the value of AUC for the thumb did not significantly
differ from the corresponding values for other fingers. Compared with the corresponding values of AUC at
4 Hz, the values of AUC were significantly larger for all fingers at 31.5 Hz (P<0.05 to 0.005; Wilcoxon
signed-ranks test), and for middle, ring and little fingers at 125 Hz (P<0.05 to 0.005; Wilcoxon signed-
ranks test). The values of AUC did not significantly differ between 31.5 Hz and 125 Hz. In this study, the
observed values of sensitivity, specificity, PPV, NPV, LR+ and LR−, and AUC indicate the effectiveness of
mechanoreceptor-specific VPT measurement in all fingers including the thumb in the diagnosis of
peripheral neuropathy in HAVS. A number of previous studies investigated the diagnostic value of VPT
measurements at different fingers in distinguishing patients with neurological HAVS3-5; however, none of
those studies investigated the thumb for that purpose which makes any comparison of the current study
findings at the thumb with those of the other fingers difficult. However, the current findings are consistent
with those from the previous studies because a higher specificity was accompanied by a relatively lower
sensitivity for all of the investigated fingers. Overall, this matched case–control study demonstrated
comparable diagnostic performance of VPT measurement at the thumb and at other fingers by the ISO-
standardized test method, for detection of peripheral neuropathy in HAVS. However, clinical, diagnostic
and prognostic importance of thumb involvement in neurological HAVS needs to be clarified further.
Table 1 Diagnostic performance of VPT test with the corresponding cut-off value for different fingers at different
test-frequencies
At 80% Thumb Index Middle Ring Little
specificity 4 Hz 31.5 Hz 125 Hz 4 Hz 31.5 Hz 125 Hz 4 Hz 31.5 Hz 125 Hz 4 Hz 31.5 Hz 125 Hz 4 Hz 31.5 Hz 125 Hz
Sensitivity (%) 50.0 83.3 63.9 41.7 75.0 75.0 47.2 80.6 75.0 41.7 88.9 80.6 52.8 80.6 80.6
PV+ (%) 72.0 81.1 76.7 68.2 79.4 79.4 70.8 82.9 79.4 71.4 82.1 80.6 73.1 80.6 80.6
PV- (%) 62.5 83.3 69.8 58.8 76.9 76.9 61.2 81.6 76.9 59.6 88.2 81.1 63.8 81.1 81.1
LR+ 2.6 4.4 3.4 2.2 4.0 4.0 2.5 5.0 4.0 2.6 4.7 4.3 2.8 4.3 4.3
LR- 0.6 0.2 0.5 0.7 0.3 0.3 0.7 0.2 0.3 0.7 0.1 0.2 0.6 0.2 0.2
Cut-off (dB) >89.8 >107.5 >122.8 >90.1 >107.6 >119.1 >91.6 >108.9 >120.8 >92.0 >107.8 >124.2 >92.5 >110.9 >125.8
References
1. Pelmear, P.L. (2003). The clinical assessment of hand-arm vibration syndrome. Occupational Medicine-Oxford
53: 337-341.
2. ISO 13091-1. Mechanical vibration—vibrotactile perception thresholds for the assessment of nerve
dysfunction—Part 1: Methods of measurement at the fingertips. Geneva, Switzerland; International Organization
for Standardization, 2001.
3. Ekenvall, L., Gemne, G., and Tegner, R. (1989). Correspondence between neurological symptoms and outcome
of quantitative sensory testing in the hand-arm vibration syndrome. British Journal of Industrial Medicine 46:
570-574.
4. Virokannas, H. (1992) Vibration perception thresholds in workers exposed to vibration. Int Arch Occup Environ
Health 64: 377-382.
5. Wenemark, M., Lundström, R., Hagberg, M., and Nilsson, T. (1996) Vibrotactile perception thresholds as
determined by two different devices in a working population. Scand J Work Environ Health 22: 204-210.
16
TEST-RETEST RELIABILITY OF
NEUROPHYSIOLOGICAL TESTS OF HAND-ARM VIBRATION SYNDROME
IN VIBRATION EXPOSED WORKERS AND UNEXPOSED REFERENTS
*Lars Gerhardsson, Lennart Gillstrom, Mats Hagberg
Occupational and Environmental Medicine, University of Gothenburg
Box 414, SE-405 30 Gothenburg, Sweden
Company Health Service, Volvo Powertrain Corporation, SE-541 36 Skovde, Sweden
Introduction
Exposure to hand-held vibrating tools may cause hand-arm vibration syndrome (HAVS)
including vibration white fingers, sensorineural symptoms and musculoskeletal disturbances.1 A
dose-response relationship has been observed between the development of sensorineural
symptoms and the level of cumulative exposure to hand-arm vibration in metalworkers.2
Quantitative sensory testing (QST) can be used to measure the sensory nerve function
noninvasively.3 Several sensory modalities may be affected by vibration exposure, which
contribute to an alteration of touch, vibration, warmth, cold and pain perception. QST has been
found to be fairly reproducible over a period of days or weeks in normal subjects.3 The aim of the
investigation was to study the test-retest reliability of hand and muscle strength tests, and tests for
the determination of thermal and vibration perception thresholds, which are often used when
investigating signs of neuropathy in vibration exposed workers.
Methods
In this study, 47 vibration-exposed workers (36 males and 11 females) who had been
investigated by the department of Occupational and Environmental Medicine in Gothenburg were
compared with a randomized sample of 18 unexposed subjects from the general population of the
city of Gothenburg. The mean age in the vibration-exposed group was 50.4 ± 12.4 y (median
exposure time 16 y) compared to 37.6 ± 15.9 y in the reference group. All participants passed a
structured interview, answered several questionnaires and were subject to a physical examination
that included hand and finger muscle strength tests and determination of vibrotactile (VPT) and
thermal perception thresholds (TPT). The participants were asked to avoid vibration exposure
during the day of the measurements and to refrain from use of tobacco and coffee/tea for at least
one hour before the start of testing. Two weeks later, 23 workers and referents, selected in a
randomized manner, were called back for the same test-procedures for the evaluation of test-retest
reliability.
Results and Discussions
The test-retest reliability after a two week interval expressed as limits of agreement (LOA;
Bland-Altman), intra-class correlation coefficients (ICC) and Pearson correlation coefficients was
excellent for tests with the Baseline hand grip, Pinch-grip and 3-Chuck grip among the exposed
workers and referents (N=23: percentage of differences within LOA 91 – 100 %; ICC-values ≥
0.93; Pearson’s r ≥ 0.93). The test-retest reliability was also excellent (percentage of differences
within LOA 96-100 %) not only for the determination of vibration perception thresholds in digits
17
2 and 5 bilaterally but also for temperature perception thresholds in digits 2 and 5 bilaterally
(percentage of differences within LOA 91 – 96 %). For ICC and Pearson’s r, although the results
for vibration perception thresholds were good for digit 2 of the left hand and for digit 5 of both
hands (ICC≥0.84; r ≥0.85), the results were lower (ICC=0.59; r=0.59) for digit 2 of the right hand.
For the latter two indices the test-retest reliability for the determination of temperature thresholds
was lower and showed more varying results.
The main findings show excellent to very good test-retest reliabilities for tests of Baseline
hand grip, Pinch grip and 3-Chuck grip as well as for the determination of vibration perception
thresholds through vibrometry. Compared to the other tests, the test-retest reliability for the
determination of temperature perception thresholds was lower with a wider spread. For TPT
determinations, LOA gave considerably higher test-retest reliability than ICC and Pearson (r).
For the diagnosis of vibration-caused neuropathy, no individual test has shown a superior
sensitivity and specificity in the assessment of its severity. Thus, multiple tests and clinical
assessments (bed-side diagnostics, e.g. needle, tuning fork, 2-PD and monofilament tests) are
needed to accurately judge and grade the sensorineural component of HAVS.4 Whether it is
sufficient with one trial or if multiple testing should be recommended to group the results for a
greater reliability of the values obtained, still needs to be investigated.
Previous studies have indicated that the reproducibility of determination of thermal
thresholds may not be as good as the determination of vibration perception thresholds. This is
reflected in our study by lower test-retest reliability for ICC and Pearson’s r, although, the
percentage of differences within LOA still remained high. The determination of temperature
perception thresholds may thus be more susceptible to the methodology used, duration of testing
and time interval between tests.3
The determination of vibration or temperature perception thresholds is relatively
complicated and time-consuming. The person that administrates the test needs to be experienced
and able to see if the subject fully understands and cooperates with the instructions. For some
subjects, the results may somewhat improve after 2-3 trials; however, due to mainly economic
reasons and time constraints, there is often only one trial per subject.
The strong test-retest reliability (repeatability) for hand and muscle strength tests as well
as for the determination of VPTs makes these procedures useful for diagnostic purposes and
follow-up studies in vibration-exposed workers.
References
1. Gemne, G. (1997). Diagnostics of hand-arm system disorders in workers who use vibrating tools.
Occup. Environ. Med. 54(2): 90-95.
2. Sauni, R., Paakkonen, R., Virtema, P., Toppila, E. and Uitti, J. (2009). Dose-response relationship
between exposure to hand-arm vibration and health effects among metalworkers. Ann. Occup. Hyg.
53(1): 55-62.
3. Chong, P.S. and Cros, D.P. (2004). Technology literature review: quantitative sensory testing. Muscle
Nerve 29(5): 734-747.
4. Heaver, C., Goonetilleke, K.S., Ferguson, H. and Shiralkar, S. (2011). Hand-arm vibration syndrome:
a common occupational hazard in industrialized countries. J. Hand. Surg. (Eur Vol) 36E(5): 354-363.
18
INFRARED THERMOGRAPHY FOR THE DIAGNOSIS OF VASCULAR
ABNORMALITES IN THE HANDS AND FEET IN HAND-ARM VIBRATION
SYNDROME
*R House+, L Holness+, I Taraschuk++
+St. Michael’s Hospital, Toronto, Ontario, Canada ++Workplace Safety and Insurance Board, Toronto, Ontario, Canada
Introduction
The traditional tests used for the diagnosis of the vascular component of HAVS (a form of
secondary Raynaud’s phenomenon), including digital thermometry and plethysmography, have not been
found to perform well in terms of sensitivity and specificity.1 Thermography, using an infrared (IR) camera,
provides a thermal image allowing simultaneous measurement of any part of the area imaged and this has
the potential for the development of an improved diagnostic test for vascular HAVS. There is evidence to
suggest that workers who develop vascular HAVS in their hands may also develop similar problems in their
feet2 and these putative effects might also be investigated by thermography of the feet. This study
investigated IR thermography as a diagnostic test for the vascular component of HAVS in the hands using
the ISO recommended cold water test parameters (12◦ C and 5 minutes of immersion)3 to determine the best
finger location, time period of re-warming and cut-off point for a positive test to maximize test performance
in terms of sensitivity and specificity. A similar investigation of the feet was done to determine the presence
of temperature differences in workers with HAVS in comparison to controls and to assess the performance
of thermography as a diagnostic test in the feet.
Methods
HAVS cases were recruited at an occupational health clinic in a teaching hospital affiliated with
the University of Toronto. Controls, with no history of Raynaud’s phenomenon, were recruited principally
from hospital and university employees. A total of 39 HAVS cases and 46 controls participated in the study.
The participants had their right hand immersed in water of 12◦ C for 5 minutes followed by measurement
of finger temperature during a re-warming period of 15 minutes. The temperatures were measured on the
ventral surface of each finger at the midpoints of the fingertips, middle phalanges and proximal phalanges.
Initial evaluation of re-warming curves indicated similar re-warming of all the fingers but not the thumb.
Therefore the four finger temperatures were averaged at each of the three finger locations. The temperatures
were compared in the cases and controls at each minute of re-warming from 0 to 15 minutes and regression
modeling was used to compare the temperatures of cases and controls over the entire 15 minute re-warming
period. The temperature data were further evaluated using a Receiver Operating Characteristic (ROC)
analysis. At each finger location the time period of re-warming with the highest area under the curve (AUC)
was chosen for calculation of sensitivity and specificity at multiple cut-off points spanning the temperature
range of subjects. In the evaluation of feet effects, 33 of the 39 HAVS cases reported cold intolerance in
their feet and therefore these 33 cases were used for comparison with the controls. The right foot was
immersed in water of 12◦ C for 5 minutes, followed by measurement of toe tip temperature each minute
during a 15 minute re-warming period. The initial rewarming curves were similar for all 5 toes and therefore
the analysis was done for each toe and the average of all 5 toes. The analysis of the feet data was similar to
the analysis of the hand data.
19
Results and Discussions
The re-warming curves indicated greater differences between cases and controls for the hands than
the feet throughout the 15 minutes of re-warming. In the analysis of the hand data, the regression modeling
indicated statistically significant differences in temperature between cases and controls throughout the re-
warming period. The greatest AUC occurred at 7 minutes of re-warming at each finger location. However
at this re-warming time the overall test performance was not optimal, with sensitivities of slightly above
80% being associated with specificities below 50%, as summarized in Table 1.
Table 1. Summary of ROC Analysis for Various Finger Locations (Average Temperatures of Digits 2-5)
Location Re-warming Time
with Highest AUC
AUC
(p value)
Sensitivity/ Specificity at Various Cut-off Points for a
Positive Test at Each Location
Sensitivity Specificity
Finger Tips 7 minutes 0.715
(p=0.002)
43.6
66.7
82.1
80.4
60.9
45.7
Middle Phalanges 7 minutes 0.719
(p=0.001)
43.6
66.7
82.1
80.4
60.9
43.5
Proximal
Phalanges
7 minutes 0.708
(p=0.002)
46.2
66.7
82.1
80.4
67.4
41.3
In the feet data, the regression analysis did not show any statistically significant temperature
differences between cases and controls modeled over the entire 15 minutes. The re-warming curves did
indicate that the temperature differences increased as re-warming progressed and therefore the temperature
differences between cases and controls were explored in more detail for each toe and the average of all toes
at each time period of re-warming. None of the temperature differences was statistically significant (p<0.05)
until the 12th minute of re-warming. Statistically significant temperature differences between cases and
controls were seen for the 3rd and 5th toes at 12, 13, 14 and 15 minutes of re-warming and for the average
of all toes at 15 minutes of re-warming. In the AUC analysis the thermography of the feet performed more
poorly, in terms of sensitivity and specificity, than the thermography of the hands (results not shown).
In summary, the IR thermography of the hands did not perform well as a diagnostic test for the
vascular component of HAVS. In the feet, although the regression analysis did not show statistically
significant temperature differences between cases and controls modeled over the entire 15 minute re-
warming period, there were statistically differences towards the end of re-warming. These findings do
suggest subtle vascular feet effects in HAVS subjects consistent with previous research.2 Future research
on thermography should evaluate re-warming beyond 15 minutes because the temperature differences did
appear to be increasing, especially in the feet, as the re-warming progressed.
References
1. Mahbub MH, Harada N. (2011). Review of different quantification methods for the diagnosis of digital vascular
abnormalities in hand-arm vibration syndrome. J Occup Health 53(4):241-49.
2. House R, Jiang D, Thompson A, Eger T, Krajnak K, Sauve J, Schweigert M. (2011).Vasospasm in the feet in
workers assessed for HAVS. Occup Med (Lond) 61(2):115-120.
3. ISO 14835-1 (2005). Mechanical vibration and shock – Cold provocation tests for the assessment of peripheral
vascular function – Part 1: Measurement and evaluation of finger skin temperature. International Organization
for Standardization, ISO, Geneva, Switzerland.
20
SOLE PHOTOGRAPHIC EVIDENCE CAN BE DECEIVING
AS A PROOF OF DIAGNOSIS IN THE MEDICOLEGAL COMPENSATION CLAIM
TO CONFIRM HAND-ARM VIBRATION SYNDROME
Siobhan C. McKay, *Sandy P. Shiralkar
The Department of Vascular Surgery, The Dudley Group NHS Foundation Trust
Dudley DY1 2HQ, West Midlands, United Kingdom
Introduction
Hand Arm Vibration Syndrome (HAVS) is a significant cause of disability worldwide, with a
prevalence of 288,000 sufferers in the UK alone in 19981. In addition to being a disabling condition for
sufferers, it is a significant cause of litigation and compensation settlement for employers. The diagnosis of
HAVS is heavily dependent on self-reporting of symptoms2. Whilst sufferers must be compensated, there
is a growing concern from employers that false claims are being lodged for monetary gains. It has been
concluded that a presenting history of Raynaud's syndrome in workers seeking compensation for HAVS
may not be accurate since approximately half the cases (43%) are unable to provide objective photographic
evidence of Raynaud's phenomenon3. For the accurate diagnosis of vascular symptoms and to confirm
HAVS, most Defendants’ experts ask for and greatly rely upon a photographic evidence revealing classical
Raynaud’s syndrome of hands.
We conducted a survey of doctors who would potentially assess HAVS patients; to investigate the
possibility of inaccurate diagnosis of Raynaud’s and subsequently HAVS based on a digitally altered
photograph.
Methods
A photograph of a normal patient’s hands
was altered digitally using Photoshop (Adobe, USA)
to show sharp demarcation with white discoloration
of the right distal two phalanges of the index and
middle fingers (Figure 1). This digital alteration was
performed within a very short period of time without
much technical support. An online survey based on the
altered photograph was sent to 48 UK consultants from
various specialities who within their clinical practice
would potentially assess patients with HAVS. This
included ten Vascular surgeons; nine Plastic hand
surgeons, ten Orthopaedic hand surgeons; ten
Rheumatologists; and nine Occupational health
physicians. The survey consisted of three clinical
questions related to the photograph and three responder
demographic questions.
Figure 1: A 48 year old man presents to outpatient
clinic with complaints of fingers turning white
especially in cold weather. He has brought a
photograph of his hands.
Please provide your spot diagnosis of this condition.
21
Results and Discussion
The current survey response rate was 54% (26 of 48 surveyed). This included four Vascular
surgeons, six Orthopaedic hand surgeons, four Plastic hand surgeons, eight Rheumatologists and four
Occupational health physicians. The number of years of experience within their specialty ranged from six
to 30 years, with a median of 15 years.
In the question provided; a history of vibration exposure was avoided to eliminate the bias. The
photograph demonstrated unilateral blanching attack thus excluding primary Raynaud’s phenomenon.
All 100% experts’ spot diagnosis was Raynaud’s; out of which 81% of responders (21 of 26)
directly responded Raynaud’s as their main spot diagnosis. The rest five sub-diagnosis were - HAVS in
12% (3 of 26); Raynaud’s or HAVS in 4% (1 of 26); and embolism in 4% (1 of 26).
Table 1: What is your differential diagnosis which is causing this condition?
Raynaud’s – 21 (81%) HAVS – 3 (21%)
Raynaud’s or HAVS – 1 (4%)
Embolic – 1 (4%)
None 0
In this survey 100% of expert responders agreed to the diagnosis of Raynaud’s in their primary spot
diagnosis. A comprehensive differential diagnosis were proposed by all except one respondent which
included – Buerger’s disease; connective tissue disease e.g. scleroderma, lupus, rheumatoid; drug related
e.g. vasospasm secondary to beta-blockers; vasculitis; MS; para-neoplastic; cryoglbulinaemia; thoracic
outlet syndrome; hyperviscosity e.g. in polycythaemia or leukaemia; hyperfibrogenaemia; cold agglutinins;
porphyria; arterial thrombosis (subclavian/ radial) - thromboembolism; surgical implants etc.
HAVS is a diagnosis of exclusion, once primary Raynaud’s and other causes for secondary
Raynaud’s have been excluded. Raynaud's is a vascular manifestation of HAVS and is typically diagnosed
by a subjective history provided by employees/ Claimants. In this survey, none of the 26 experts indicated
any suspicion or doubt about the validity /authenticity of the photograph and all arrived at the diagnosis of
Raynaud’s syndrome.
This survey demonstrates that an easily altered photograph can convincingly appear to demonstrate
Raynaud’s; which is a vascular component of HAVS. Therefore in conclusion, just a photographic evidence
cannot be profoundly relied upon to agree/ confirm the diagnostic of HAVS.
References
1. Palmer, K.T., Coggon, D.N., Bendall, H.E., Kellingray, S.D., Pannett, B., Griffin, M.J., and Harward,
B.M. (1999). Hand-transmitted vibration: occupational exposures and their health effects in Great
Britain. Health and Safety Executive, United Kingdom.
2. Poole, K. (2009). A review of the literature published since 2004 with potential relevance in the
diagnosis of HAVS. Health and Safety Executive, United Kingdom.
3. Sami Youakim (2008). The validity of Raynaud's phenomenon symptoms in HAVS cases. Occup Med
(Lond) 58 (6):431-435.
22
FINGER REWARMING TIME IN HEALTHY MEN AND WOMEN: EFFECTS OF
ROOM TEMPERATURE AND GENDER
*Ying Ye and Michael J Griffin
Human Factors Research Unit, Institute of Sound and Vibration Research, University of
Southampton, Southampton SO17 1BJ, England
Introduction
Vibration-induced white finger (VWF) is the vascular component of the hand-arm
vibration syndrome (HAVS). International standard 14835:2005 defines two tests to assist the
diagnosis of VWF: the measurement of finger rewarming time and the measurement of finger
systolic blood pressures.1 It has been suggested that the diagnostic value of the finger rewarming
test depends on environmental conditions.2,3 This study investigated the effects of both room
temperature and gender on the finger rewarming test. It was hypothesised that with increased room
temperature finger rewarming time would decrease. Women were expected to have lower initial
finger skin temperatures (FSTs) and longer rewarming time than men.
Methods
Twelve men and twelve women with a mean
age of 24.3 years (SD: 3.1; range: 18-30) participated
in two sessions. Before the test started, subjects were
in one of two room temperatures (20 or 28°C) for at
least 30 minutes or until they had a constant FST
(<1ºC variation over 10 minutes). Finger rewarming
was measured by an experimenter experienced in
applying the test according to the recommended
procedure.1,4
An HVLab 8-channel temperature monitor
(University of Southampton) measured finger
temperatures (Fig. 1). Thermocouples were attached
to the palmar surfaces of the distal phalanges of the
thumb, index, ring, and little fingers, and the distal,
median, and proximal phalanges of the middle finger
of the right hand. The hand was covered by a thin loose waterproof glove. After a resting period
of 2 minutes, the right hand was immersed in stirred water at 15°C for 5 minutes. The hand was
then removed from the water with the help of the experimenter, the glove was removed, and the
hand remained motionless while rewarming over 40 minutes. The skin temperature was monitored
continuously during the settling period, the cooling period, and the rewarming period using a
computer and HVLab diagnostic software (version 8.5, University of Southampton).
Results and Discussion
Median finger skin temperatures on the distal phalanx of the right hand before, during, and
after cold provocation with room temperatures of 20 and 28°C are shown for males and females
in Fig. 2.
Fig. 1: Immersion of a gloved right hand in
stirred water at 15 °C.
23
During the 2-minute
resting period, FSTs were
higher in the higher room
temperature in both men and
women (p < 0.01). The FSTs
during this period were lower
in women than in men at both
room temperatures (p < 0.001).
During the 5-minute
cooling period, there was
greater reduction in FSTs with
the higher room temperature in
both men and women (p <
0.001). The reduction in FST
was greater in men than in
women (p < 0.05).
During the first 8
minutes of the recovery period,
the median FST increased at
3.2°C/min in men and 2.0°C/min in women with the 28°C room temperature, but at only 1.8°C in
men and 1.7°C/min in women with the 20°C room temperature. Subsequently, the median FSTs
show steady rewarming with the 28°C room temperature, but with the room temperature at 20°C
the rate of increase in median FST decreased to 0.1°C/min in men over a 3-minute period and in
women over an 7-minute period. Thereafter, the rate of increase in median FST remained at 1.0-
1.2°C/min until the median FST recovered to the initial temperature. The time for individual FSTs
to return to within 2°C of the initial finger temperature was shorter with the higher room
temperature in both men and women (p < 0.01), and shorter in men than in women at both room
temperatures (p < 0.001).
The results show that increased environmental temperature shortens rewarming time and
that men have shorter rewarming time than women. Variation in the rate of rewarming with a 20°C
room temperature suggests vasodilation during recovery is not mediated solely by gradual release
of arterial vasospasm but through a combination of processes.5
The study shows that room temperature affects the accuracy of the finger rewarming test,
and that a criterion for normal rewarming time developed for men will not apply to women.
References
1. International Organization for Standardization (2005) Mechanical vibration and shock – cold provocation tests
for the assessment of peripheral vascular function – Part 1: Measurement and evaluation of finger skin
temperature. International Standard, ISO 14835-1.
2. Bovenzi M (1987) Finger thermometry in the assessment of subjects with vibration-induced white finger. Scand
J Work Environ Health 13: 348-351.
3. Virokannas H and Rintamäki H (1991) Finger blood pressure and rewarming rate for screening and diagnosis of
Raynaud’s Phenomenon in workers exposed to vibration. Br J Ind Med 48: 480-484.
4. Lindsell C and Griffin MJ (1998) Standardised Diagnostic Methods for Assessing Components of the Hand–Arm
Vibration Syndrome, CRR 197/1998, Sudbury, Suffolk: HSE Books, 1–87.
5. Lindsell C and Griffin MJ (2001) Interpretation of the finger skin temperature response to cold provocation. Int
Arch Occup Environ Health 74:325–335.
Fig. 2: Median finger skin temperatures before, during, and after
immersion of the hand in stirred water at 15 °C.
0
5
10
15
20
25
30
35
40
0 5 10 15 20 25 30 35 40 45 50
Male: 28 C
Female: 28 C
Male: 20 C
Female: 20 C
Time (minutes)
Recovery periodF
ing
er
skin
tem
pera
ture
( C
)
Resti
ng
peri
od
Co
oli
ng
peri
od
24
FINGER SKIN TEMPERATURE DURING COLD WATER IMMERSION TEST
FOR DIAGNOSING HAND-ARM VIBRATION SYNDROME
IN DIFFERENT CLIMATES IN CHINA
Bin Xiao, Danying Zhang, Aichu Yang, Guiping Chen, Li Lang, Hansheng Lin,
Xuqing Cao, Guoyong Xu, *Qingsong Chen
Guangdong Province Hospital for Occupational Disease Prevention and Treatment; Guangdong
Provincial Key Laboratory of Occupational Disease Prevention and Treatment, Guangzhou,
Guangdong 510300, China
Correspondence to: [email protected]
Introduction
Finger skin temperature (FST) during immersion testing has been proposed as a useful
method for diagnosing hand-arm vibration syndrome (HAVS)1,2. FST is widely used in temperate
environments; however, few studies of the use of FST during immersion testing in subtropical
environments have been performed. This study aimed to assess the differences in FST values
during immersion testing (10°C, 10 min) in temperate versus subtropical environments in China
for the purposes of diagnosing HAVS.
Methods
Two groups of subjects were involved in this study: 100 workers from Guangdong province
(subtropical environment, group A) and 99 workers from Shandong province (temperate
environment, group B). Both groups were initially divided into three subgroups: HAVS, vibration-
exposed controls (VEC), and non-vibration-exposed controls (NVEC)1,3. Cold water immersion
testing was performed on all subjects during the winter, in which individuals immersed their hands
in 10°C water for 10 min after a 30-minute break. The FST of the ring finger of the dominant hand
was measured every 5 min by an infrared thermometer before and after testing. The FST at 0, 5,
10, and 30 min after testing (T0, T5, T10, and T30) and rewarming rate at 5 and 10 min after testing
(R5 and R10) were determined. An ANOVA was used to analyze differences between groups. The
sensitivity and specificity of statistically different results were analyzed between patients and
control subjects using ROC curves.
Results and Discussions
For group A, there were no statistically significant differences found for baseline temperature,
T0, T5, T10, R5, or R10 among the three subgroups. The only statistically significant difference
in this group was observed at T30 (Table 1). For group B, no statistically significant differences
were observed for baseline temperature, T0, R5, or R10 among the three subgroups. The T5, T10,
and T30 of the HAVS group were significantly lower than those of the other subgroups (Table 1).
In addition, the ROC areas (95%CI) of T5 and T10 in group B were 0.759(0.644, 0.874, P<0.01)
and 0.757(0.639, 0.875, P<0.01), respectively (Figure 1). This study demonstrated that the cold
water immersion test (10℃, 10 min) has excellent value in supporting the clinical diagnosis of
HAVS in temperate environments. In addition, T5 may also be a good indicator of diagnosis.
However, FST did not appear to be useful for diagnosing HAVS in a subtropical environment.
25
Table 1. Temperature differences before and after cold water immersion testing in different
groups.
Group A,
( n=100)
Group B
( n=99)
NVEC
(n=37)
VEC
( n=37)
HAVS
( n=26)
NVEC
( n=37)
VEC
( n=42)
HAVS
( n=20)
Pre, °C 27.6±4.4 28.5±4.3 27.9±4.6 27.6±4.4 28.8±4.2 26.2±4.5
T0, °C 12.0±1.5 11.3±1.5 11.8±1.6 11.7±1.2 11.9±1.1 11.2±1.2
T5, °C 16.3±3.2 15.1±1.5 15.0±3.8 16.2±3.4 17.4±3.5 14.0±2.1*#
T10, °C 19.8±5.0 18.6±3.2 18.6±6.1 19.9±5.9 21.6±5.3 16.4±3.6*#
T30, °C 24.0±5.0 27.3±4.7* 24.4±7.4 24.8±5.6 27.9±5.0 22.7±5.6#
R5, % 27.2±14.9 23.4±10.4 18.3±17.6 27.6±16.0 28.8±16.2 19.2±9.9
R10, % 48.8±23.8 43.4±17.1 39.5±28.1 49.5±27.4 50.9±28.8 35.7±20.7
* compared with NVEC, p<0.05；# compared with VEC, p<0.05
References
1. Laskar S, Harada N. Different conditions of cold water immersion test for diagnosing hand-arm
vibration syndrome. Environmental Health and Preventive Medicine, 2005, 10(6): 351-359.
2. National Occupational Health Standard in China(GBZ7-2014)(2014):Diagnostic Criteria of
Occupational Hand-Arm Vibration Disease.Ministry of Public Health,Beijing.
3. Poole K, Elms J, Mason H. Modification of the Stockholm vascular scale. Occupational Medicine,
2006, 56(6): 422-425.
Figure 1: The ROC curves of T5 and T10 for diagnosis HAVS in Group A and Group B
26
Session III: Vibration Measurement
Chairs: Tammy Eger and Enrico Marchetti
Presenter Title and authors Page
Ren G. Dong Hand-arm coordinate systems for measuring vibration
exposure, biodynamic responses, and hand forces
Ren G. Dong, Erik W. Sinsel, Daniel E. Welcome,
Christopher Warren, Xueyan S. Xu, Thomas W.
McDowell, John Z. Wu
27
Uwe Kaulbars Determining the measurement uncertainty of workplace
measurements conforming to GUM
Uwe Kaulbars
29
David Rempel Comparison of handle vibration for hammer drills using a
new test bench system
David Rempel, Alan Barr, Andrea Antonucci
31
Krishna Dewangan Evaluations of low-cost resistive sensors for
measurements of hand forces on vibrating handles
Subhash Rakheja, Pierre Marcotte, Krishna Dewangan,
M. Kalra
33
27
HAND-ARM COORDINATE SYSTEMS FOR MEASURING VIBRATION EXPOSURE,
BIODYNAMIC RESPONSES, AND HAND FORCES
*Ren G. Dong, Erik W. Sinsel, Daniel E. Welcome, Christopher Warren,
Xueyan S. Xu, Thomas W. McDowell, John Z. Wu
Engineering and Control Technology Branch, Health Effects Laboratory Division,
National Institute for Occupational Safety & Health, Morgantown, WV, USA
Introduction
Two types of hand coordinate systems for measuring vibration exposures and biodynamic
responses have been standardized in ISO 8727 (1997)1 and ISO 5349-1 (2001)2. They are termed as
basicentric (BC) and biodynamic (BD) coordinate systems, respectively. They are different from those
actually used in tool testing standards and biodynamic measurements, which casts doubt on their suitability
and usefulness. The objectives of this study were to identify the major sources of the problems and to help
define or identify better coordinate systems.
Methods
This study systematically reviewed and clarified the principles and definitions of the BC and BD
coordinate systems. Several typical hand and arm coordinate systems (Figure 1) were evaluated. The typical
working postures of the hand and arm during the operation of more than 15 types of powered hand tools,
together with conventional postures used in hand-arm vibration laboratory experiments, were considered in
the review and evaluation. The relationships (γ and β angles) among BD coordinate systems shown in
Figure 1(b) were also measured. 20 subjects participated in the experiment. The results were used to
enhance the evaluation and to estimate the principal grip force in these BD systems.
Figure 1: Various hand and arm coordinate systems
(a) Basicentric coordinate systems: the ISO system (h-BC)
illustrated in the figure of the standards1,2; the ISO
system (ISO-BC) interpreted from the written
definition in ISO 87271; the BC system recommended
in ISO 28927 (BC)3; and BS EN system (EN)4.
(b) Biodynamic coordinate systems: the standard
BD system (h-BD)1,2; the forearm-based BD
system (Forearm); the thenar region-based BD
system (Thenar)5; and the metacarpal joint
head-based BD system (MJH)6.
28
Results and Discussion
This study confirms that it is reasonable to define two types of coordinate systems for studying
hand-transmitted vibration, as accelerometers remain the most convenient and effective technology for
measuring vibration exposures and biodynamic responses. While the basicentric coordinate system is
primarily defined for guiding the installation of the accelerometer on a handle to measure vibration
exposures, the biodynamic coordinate system is defined primarily for describing, measuring, and analyzing
hand and arm postures and biodynamic responses. The standard BC system is neither clearly defined nor
correctly illustrated in the current standards1,2; as a result, it is interpreted differently in some other standards
and in reported studies. For example, the ISO-BC system we interpreted from the written definition included
in ISO 8727 is different from the standard illustration, as shown in Figure 1(a). The tool-specific BC system
(BC system) recommended in ISO 28927 (2009-2012)3 is consistent with the written definition except for
the swapping of the x and z axes. Furthermore, the zBC axis on a non-right-angle tool handle should not be
required to be fully aligned with the functional or action direction of the tool, as the alignment of the yBC
axis with the handle axis cannot make the zBC axis fully in line with the action direction of such a tool. The
BS EN system4 is also reasonable if its xEN axis refers to the dominant vibration direction.
Multiple BD coordinate systems are actually required to describe the postures of the hand and arms
and to measure the biodynamic responses and hand forces. It is neither necessary nor convenient to define
the BD system based on the bony anatomy principle adopted in ISO 87271 or ISO 5349-12, as such a
principle is actually not suitable to the study of hand-arm vibration exposures or biodynamic responses.
Although the standardized hand BD system (h-BD system in Figure 1(b)) is claimed to be precisely defined
based on the bony anatomy principle, this system is not convenient, and it does not have any unique
biological basis or biodynamic foundation. For these reasons, its usefulness is very limited. In contrast, the
thenar region-based BD system initiated from our previous study is much more meaningful, convenient,
and implementable5. The forearm-based coordinate system is also a useful BD system. The MJH system
was used to measure grip force6. It can also be used in the study of vibration, but it is not a convenient
system and it varies with handle size. The relationships among the BD systems identified in this study
suggest that the principal direction of grip force is approximately correlated with the index fingertip location
on cylindrical handles. When the principal grip force is of concern, the index fingertip-based coordinate
system should be considered to perform the measurement.
References
1. ISO 8727. Mechanical vibration and shock - Human exposure-Biodynamic coordinate systems. International
Organization for Standardization, Geneva, Switzerland, 1997.
2. ISO 5349-1: Mechanical vibration - Measurement and evaluation of human exposure to hand-transmitted
vibration - Part 1: General requirements. International Organization for Standardization, Geneva, Switzerland,
2001.
3. ISO 28927 (from Part 1 to Part 12): Hand-held portable power tools -- Test methods for evaluation of vibration
emission. International Organization for Standardization, Geneva, Switzerland, 2009-2012.
4. BS EN 60745-1. Hand-held motor-operated electric tools. Safety. General requirements. British Standards
Institution, 2009.
5. Dong R.G., Welcome D.E., Warren C., Dong C.L., McDowell T.W., Wu J.Z., A novel theory: ellipse of grip
force. Proceedings of the 1st American Conference on Human Vibration, Morgantown, WV, June 2006.
6. Edgren, C.S., Radwin, R.G., Irwin, C.B., 2004. Grip force vectors for varying handle diameters and hand sizes.
Human Factors 46 (2): 244-251.
29
DETERMINING THE MEASUREMENT UNCERTAINTY OF WORKPLACE
MEASUREMENTS CONFORMING TO GUM
Uwe Kaulbars
IFA – Institute for Occupational Safety and Health of the German Statutory
Accident Insurance – (IFA, formerly BGIA), Alte Heerstrasse 111, 53757 Sankt Augustin
Introduction
For an assessment of the reliability of measurement results, it is essential that
measurements are correctly performed and that the measurement uncertainty is known. To obtain
information on the quality of the measurement results from different laboratories, knowledge of
the measurement uncertainty is required even in the case of standardised and "error-free"
measurements. This becomes increasingly important when measured data are supplied to databases
from different sources. More precise calculations of the measurement uncertainty are also required
for the validation of hazard analyses and for vibration reduction forecasts and programmes.
A uniform guide for different measurement quantities has been available for 20 years in
the shape of the Guide to the Expression of Uncertainty in Measurement (GUM)1. Since it has not
so far been applied to the field of human vibration exposure owing to the unacceptably high
complexity of the task, DIN SPEC 45660-22 has been produced in Germany.
This technical report contains examples of the measurement uncertainty of vibration
exposure calculated from activity-related measurements to ISO 5349-23. The guide values of the
measurement uncertainty contributions used are based among other things on an inter-laboratory
test organised by IFA. The goal of the test was to determine the measurement uncertainty for
standardised measurements.
Methods
To ensure the same conditions for the duration of the
inter-laboratory test, a fictitious workplace was set up for three
tasks to be performed by two experienced workers. The tasks
consisted of cutting square tubes with a pneumatic angle grinder,
drilling dowel holes with an electric rotary hammer and cutting
contours in glulam worktops with an electric jig saw (see Fig.
1).
Seven laboratories accredited to ISO/IEC 170254 took
part in the inter-laboratory test. Each laboratory carried out its measurements independently on a
separate day. To ensure uniformity, new tools and materials were used on each day of measurement
and the proceedings were monitored by an independent observer. To compare the series of
measurements, additional control tasks were carried out with a calibrator for three fixed
frequencies and amplitudes.
Results and Discussions
Each laboratory evaluated its own data and conducted a risk assessment. All the data were
evaluated by the neutral Institute for Proficiency Tests (IfEP) in conformity with ISO/IEC 170435,
ISO 135286 and ISO 5725-27.
Fig. 1: Measurement tasks
30
The calculation model for measurement uncertainty to DIN SPEC 45660-22 is based on the
main uncertainty contributions presented in Table 1. The laboratory standard deviation 𝑢𝑀 is
obtained with the following equation:
𝑢𝑀 = √ 𝑢𝑀𝑒𝑎𝑠𝑢𝑟𝑖𝑛𝑔 𝑖𝑛𝑠𝑡𝑟𝑢𝑚𝑒𝑛𝑡2 + 𝑢𝐶𝑜𝑢𝑝𝑙𝑖𝑛𝑔
2 + 𝑢𝑆𝑒𝑛𝑠𝑜𝑟 𝑝𝑜𝑠𝑖𝑡𝑖𝑜𝑛2
To validate the
calculation model conforming
to DIN SPEC 45660, the
measurement uncertainties of
the respective overall vibration
values are calculated in
accordance with EUROLAB
TR 1/20068 and compared. The
results from the two models
were largely identical, although
the EUROLAB model tended to
show higher values. In addition,
the trueness and precision of all
measurement results were
determined and the reprodu-
cibility, repeatability and
laboratory standard uncertainty
were calculated.
Table 1: Orientation values of the measurement uncertainty contributions DIN
SPEC 45660
The inaccuracy data of all the measuring instruments are based on the supplements to measuring
instrumentation standard ISO 80419.
References
1. ENV 13005 Guide to the expression of uncertainty in measurement GUM
2. DIN SPEC 45660-2 Guide for dealing with uncertainty in acoustics and vibration – Part 2: Uncertainty of
vibration quantities
3. ISO 5349-2(2001) Mechanical vibration - Measurement and evaluation of human exposure to hand-transmitted
vibration - Part 1: General requirements, Part 2: Practical guidance for measurement at the workplace
4. ISO/IEC 17025(2005) General requirements for the competence of testing and calibration laboratories
5. ISO/IEC 17043(2010) Conformity assessment - General requirements for proficiency testing
6. ISO 13528(2005) Statistical methods for use in proficiency testing by interlaboratory comparisons
7. ISO 5725-2(1994) Accuracy (trueness and precision) of measurement methods and results - Part 2: Basic method
for the determination of repeatability and reproducibility of a standard measurement method
8. EUROLAB Technical Reports 1/2006, Guide to the Evaluation of Measurement Uncertainty for Quantitative Test
Results
9. ISO 8041 Human response to vibration - Measuring instrumentation, Amendment (2015)
Acknowledgements
Our thanks go to the Institute for Proficiency Tests (IfEP), Marl, Germany, and to the participating laboratories: German
Social Accident Insurance Institution for the woodworking and metalworking industries, German Social Accident
Insurance Institution for the raw materials and chemical industry, Ingenierbüro Gillmeister, Brandenburg's Land
laboratory, Müller BBM GmbH, SLG Prüf- und Zertifizierungs GmbH.
31
EVALUATION OF HANDLE VIBRATION FOR HAMMER DRILLS
USING A NEW TEST BENCH SYSTEM
*David Rempel, Alan Barr, Andrea Antonucci
Ergonomics Graduate Training Program, Department of Bioengineering,
University of California, Berkeley, CA, USA
Introduction
Drilling holes into concrete is a common task in commercial construction required for placing anchor bolts
that support pipes, conduit, ducts or machinery or for setting rebar (e.g., dowel and rod drilling) for structural retrofits,
seismic upgrades or extending roads and tarmacs. The typical handle vibration levels for this work are 8-16 m/s² for
hammer drills and 14-20 m/s² for pneumatic rock drills (Griffin 2006).
Test bench methods have been developed for evaluating silica dust from cement cutting tools (Akbar-
Khanzadeh 2010) but not for handle vibration using concrete drills and there are no international standards for such
test bench systems. Instead, international standards call for handle vibration to be measured in controlled settings
while workers use the drill (ISO 28927- 6&10). There is a concern that a test bench may constrain the system in ways
that will alter handle vibration as compared to vibration experienced by workers. The purpose of this project was to
develop and evaluate an automated test bench system in order to evaluate drill handle vibration under different
conditions of concrete drilling.
Methods
A test bench system was designed and built with the following features: (1) automatically controls an active
drill and advances it into concrete under force control, (2) automatically advances concrete blocks between holes, (3)
accommodates a wide variety of drill types, and (4) continuously records handle vibration. The drill is firmly coupled
to a saddle that is moved horizontally by a linear actuator under force control (e.g., feed force (FA) = weight on bit
(WOB)) managed by a custom LabView program on a PC. The drill is secured to the saddle with ring clamps at the
drill handle; between the clamps and the drill a 1 cm thick rubber/foam is inserted with stiffness properties similar to
palmar skin. The activated drill drills into a concrete block to a specified depth (up to 250 mm) at a constant feed force
(adjustable range: 50 and 500 N) and is automatically withdrawn. After each hole is drilled the concrete block is
advanced so that the next hole can be drilled. The drill saddle is coupled to a single axis load cell with a stiff spring
aligned to the drilling axis (Figure 1). The load cell is moved by the linear actuator on a lathe bed. Non-reinforced
concrete blocks (3.5 x 12 x 12”) are made with quality is consistent with reinforced structural concrete (slump 80 mm;
EN 206-1:2000).
A tri-axial accelerometer (Larson Davis HVM100) was attached to the drill handle using hose clamps and
the signal was sampled at 1Hz and stored to a computer. The accelerometer and load cell were calibrated prior to use
(PCB Piezotronics shaker 394C06). Tool handle vibration acceleration magnitude was measured and interpreted
according to ISO standards (ISO 28927-6&10).
Figure 1. Mechanical model of system with linear actuator (left), stiff spring (k1, c1), load cell and drill saddle
(m1), drill mount (mass), rubber interface (k2, m2, c2), and drill (a).
32
Validation of the test bench system was assessed by comparing test bench results to those from 4 experienced
construction workers drilling 5 holes per test condition, following ISO methods. Subjects signed a written consent
form and the study was approved by the University Committee on Human Research. Subjects drilled vertically into
concrete block to measure thrust force while subjects stood on an electronic force plate (Sampling rate 25Hz; Acculab
Digital Scale, Bradford, MA). The workers were instructed to apply thrust force similar to their usual drilling. Handle
vibration measurements were similar to measurement on the test bench system.
Four test conditions were evaluated on the test bench: two electric hammer drills (TE40 and TE7, Hilti), each
with a 3/8 and 3/4" concrete bit. For each condition, 5 holes were drilled to 125 mm (ISO 28927-10) with a target
linear force of 90N. Two test conditions were evaluated by the human studies: the same two electric hammer drills
with the 3/8” bit. Human testing was not done with the 3/4” bit. Productivity was measured as drilling time to
complete drilling depth.
Results and Discussion
Summary measures of findings (mean (SD)) are presented in the Table below.
Drill Bit Holes
Linear Force
(N)
Drilling
Time (s)
Mean Peak
Vibration (m/s²)
Mean Mean
Vibration (m/s²)
TEST BENCH
TE40 3/4" 21 90.2 (3.8) 32.7 (1.4) 17.0 (2.0) 7.2 (0.5)
TE7 3/4" 16 89.7 (1.8) 78.8 (4.0) 29.1 (1.6) 9.0 (0.3)
TE40 3/8" 11 73.3 (4.3) 13.5 (0.6) 16.2 (2.1) 7.1 (1.1)
TE7 3/8" 22 88.5 (9.5) 15.2 (1.1) 31.1 (0.6) 9.5 (0.2)
HUMAN TESTING (N=4)
TE40 3/8" 5 74.6 (4.1) 24.4 (1.6) 7.9 (1.0)
TE7 3/8" 5 81.6 (23.0) 31.5 (5.3) 10.1 (1.0)
Linear force for the test bench was close to target values of 90N with low variance for the ¾” bit. The 3/8”
bit was undersized for the TE40 leading to difficulty maintaining constant feed force. The self-selected linear force
by workers was somewhat less than the force used for the test bench. As expected, the coefficient of variance (CV)
for linear force for the workers was higher (0.05 to 0.28) than the test bench (0.02 and 0.11).
Mean vibration levels were similar between the test bench and the human testing. Mean peak vibration levels
were similar for the small drill but not the large drill.
The test bench system included foam rubber damping at the coupling to the drill handle designed to be similar
to the palm coupling. In addition, a stiff spring isolated the drill from the linear actuator, mimicking the role of the
forearm and upper arm. It appears that the masses of the saddle and load cell provided a response that was similar to
the human system (Dong 2010). Future validation studies should involve larger bits (e.g., 5/8” and 3/4”) that are more
appropriate for the drills tested.
The test bench methods differ from the ISO standard in several ways. The ISO standard calls for drilling
downward, but when drilling downward with an electric hammer drill, the bit will bind in a 250 mm depth hole because
there is no air flushing of the dust. So drilling on the test bench was done horizontally to prevent bit binding. In
addition, the ISO standard calls for subjects do the drilling. This may lead to handle grip force and force on tip that
are similar to work. However, this approach is also associated with increased variance in measures while the robotic
system minimizes variance. The problem of robotic system not matching real world grip and feed force can be
addressed by having the robotic system perform testing under different feed force and grip force levels. This approach
may provide greater insights into drill design and vibration and may influence instructions to end-users. A test bench
system for concrete drilling can provide information that compliments data from human compliance testing.
References
1. Dong R, Rakheja S, McDowell T, Welcome D, Wu J. Estimation of the Biodynamic Responses Distributed at
Fingers and Palm Based on the Total Response of the Hand-Arm System. Int J Ind Ergon 2010; 40(4): 425-436.
2. ISO 28927-10 (2011): Hand-held portable power tools – test method for evaluation of vibration emission – Part
10: Percussive drills, hammers and breakers. Geneva: International Organization for Standardization, Geneva.
33
EVALUATIONS OF LOW-COST RESISTIVE SENSORS FOR MEASUREMENTS OF
HAND FORCES ON VIBRATING HANDLES
Subhash Rakheja+, Pierre Marcotte++, *Krishna Dewangan+++, M. Kalra+
+Concave Research Centre, Concordia University, Montreal, QC, Canada ++IRSST, Montreal, QC, Canada
+++North Eastern Regional Institute of Science & Technology, Nirjuli, India
Introduction
The hand-handle coupling force, often considered as the summation of the grip and push
forces, permits the flow of vibration energy from the tool into the palm of the hand and arm. The
coupling force thus directly affects the nature of hand transmitted vibration (HTV) and hand-arm
biodynamics. Although the significance of coupling force with regard to quantifying the hand-arm
vibration (HAV) exposure has been widely recognized, the measurements of hand forces on
vibrating tools have met only limited success due to lack of a reliable measurement system and
definite relations between the static coupling force and HTV. Lemerle et al. [1] explored a
capacitive pressure sensing matrix to measure push and grip forces on power tools. The
measurement system, however, is not considered well-suited for field applications due to its very
high cost, while its validity for measuring dynamic forces in frequency ranges of power tools has
not been demonstrated. In this study, low-cost resistive sensors (FlexiForce) are evaluated for
measuring hand forces on a percussion tool handle under stationary and vibration conditions. The
feasibility of the sensor is also evaluated for measuring biodynamic responses of the hand-arm
system.
Methods
The experiments were initially conducted to assess applicability of
low-cost resistive sensors (FlexiForce) for measurements of hand forces on
a chipping hammer positioned in an energy dissipater and hand-arm
biodynamic responses using 3 and 6 subjects, respectively. Two sensors
were applied on the top and bottom surfaces of the primary tool handle for
measurements of palm and finger forces (Fig. 1), which were used to
estimate hand grip and push forces, as described in [2]. Each subject stood
on a force plate nearly upright and gripped the tool handle in a power grip
manner. The static sensitivity of each sensor was evaluated for each subject
over the 150 N force range through calibrations. The validity of the
measurements was evaluated, while subjects grasped the stationary tool
handle with 5 different combinations of grip and push forces.
Measurements were repeated while the subject operated the tool. The force plate and finger-side
sensor signals were displayed to the subject to apply controlled forces, while the palm sensor signal
was hidden from the subject. The correlations between the push force estimated from FlexiForce
sensors and force plate output, and between palm sensor force and the coupling force were
evaluated under both stationary and vibrating conditions.
In the second experiment, two FlexiForce sensors were applied symmetrically about the
center line of a 38 mm diameter instrumented handle along the forearm-axis for measuring the
Palm sensor
Finger sensor
Fig.1: FlexiForce sensors
applied to tool handle
34
hand-arm biodynamic response. The palm and finger-side forces were acquired under different
combinations of hand grip and push forces, and two levels of broadband random vibration in the
4–1000 Hz range (frequency-weighted rms acceleration: 1.5 and 3 m/s2). The force signal from
the instrumented handle was analyzed to obtain the reference biodynamic responses in terms of
driving-point mechanical impedance (DPMI). The palm and finger FlexiForce sensors signals
were analyzed to compute the palm- and fingers-side DPMI responses. Each measurement was
repeated twice. The data were acquired for a duration of 20 s during each measurement. A
frequency correction function, derived from the frequency response of the sensors, was applied to
compensate for limited bandwidth of the sensors, as described in [3]. The validity of the FlexiForce
sensors for measuring biodynamic response was assessed through comparisons with the reference
DPMI responses under different vibration and hand forces considered.
Results and Discussions
Figure 2(a) illustrates correlations of push force estimated from FlexiForce sensors with
those obtained from the force plate for the 3 subjects operating the power tool (r2: 0.82–0.95).
Very good correlations were also obtained between the palm sensor measurements and the
coupling force (r2: 0.93–0.98). The ratio of push force obtained from FlexiForce sensors to force
plate signal ranged from 0.94–1.08 for the three subjects, while that of the palm force to the
coupling force ranged from 0.96–1.05. The results further showed good repeatability of sensors
applied to the tool handle. Figures 2(b) and 2(c) compare the corrected and uncorrected palm and
finger DPMI magnitudes obtained from FlexiForce sensors with the reference responses from the
instrumented handle under 3 m/s2 excitation (grip/push forces: 30/50 N). The results show that
corrected responses from the sensors agree well with the reference values. The uncorrected
responses of the sensors, however, resulted in substantially lower DPMI magnitudes, although
these show good trends. This was attributed to the limited frequency response of the sensors.
Fig. 2: Correlations of push force data obtained from FlexiForce sensors and force plate for each
subject grasping the vibrating tool handle (a); and comparisons of corrected and uncorrected
palm (b) and finger (c) impedance responses with the reference responses
References
1. Lemerle P, Klinger A, Cristalli A, Geuder M, 2008. Application of pressure mapping techniques to measure push
and gripping forces with precision. Ergonomics 51(2), 168–191.
2. Marcotte P, Adewusi S, Rakheja S, 2011. Development of a low-cost System to Evaluate Coupling Forces on
Real Power Tool Handles. Canadian Acoustics 39(2), 36–37.
3. Dewangan KN, Rakheja S, Marcotte P, Shahmir A, Patra SK, 2013. Comparisons of apparent mass responses of
human subjects seated on rigid and elastic seats under vertical vibration. Ergonomics 56, 1806–1822.
(a) (b) (c)
Ph
ase
35
Session IV: Vibration Reduction and Exposure Control
Chairs: David Rempel and Uwe Kaulbars
Presenter Title and authors Page
Tammy Eger Evaluation of personal protective equipment as a control
strategy to reduce foot-transmitted vibration
Heather Byrnell, James P. Dickey, Alison Godwin and
Tammy Eger
36
Eckardt Johanning Tools of the trade– maintenance of way tools ergonomic
and vibration risk assessment
Eckardt Johanning, Paul Landsbergis, Rick Inclima
38
Marco Tarabini Reduction of the vibration transmitted to the hand by the
chisel of pneumatic chipping hammers
Diego Scaccabarozzi, Bortolino Saggin and Marco
Tarabini
40
Hans Lindell Hand-held impact machines with nonlinearly-tuned
vibration absorber
Hans Lindell, Viktor Berbyuk, Snævar Leó Grétarsson,
Mattias Josefsson
42
Ren G. Dong The effect of a mechanical arm tool support system on
workplace grinder vibrations
Thomas W. McDowell, Daniel E. Welcome, Christopher
Warren, Xueyan S. Xu, and Ren G. Dong
44
36
EVALUATION OF PERSONAL PROTECTIVE EQUIPMENT AS A CONTROL
STRATEGY TO REDUCE FOOT-TRANSMITTED VIBRATION
Heather Byrnell+, James P. Dickey++, Alison Godwin+ and *Tammy Eger+
+Centre for Research in Occupational Health Safety, Laurentian University, Sudbury, ON, Canada
++School of Kinesiology, Western University, London, ON, Canada
Introduction
Occupational exposure to foot-transmitted vibration (FTV) occurs when a worker is
exposed to vibration that travels through the feet. In underground mining, exposure typically
occurs when standing on vibrating surfaces associated with the operation of locomotives, jumbo
drills, bolters, or raise platforms. Recent medical evidence confirms workers exposed to FTV can
develop cold induced blanching of the toes and permanent disruption of blood circulation and
innervation to the toes and feet leading to an occupational disease termed vibration induced white-
feet1. As part of a vibration management program some companies have started to use “anti-
vibration” mats and insoles in an effort to reduce harmful vibration levels. However, there are no
controlled studies that show the effectiveness of personal protective equipment (PPE) such as mats,
boots, or insole for vibration reduction. The primary objective of this study is to evaluate the
effectiveness of combinations of mat/workboot/insole for attenuation of FTV.
Methods
Three mats (M0=no mat; M1=mat 1; M2=mat 2), three boot (B1=boot 1; B2=boot 2; B3=
boot 3), and four insole conditions (I0=no insole; I1=insole 1; I2=insole 2: I3=insole3) were
randomly tested in combination at dominant FTV exposure frequencies associated with operating
a locomotive (3 Hz, Ax= 0.48, Ay=0.57, Az=0.84 m/s2), jumbo drill and bolter (30 Hz, Ax= 5.9,
Ay=7.18, Az=2.66 m/s2), and drilling off a raise platform (40 Hz, Ax= 2.0, Ay=3.22,
Az=5.59 m/s2)2. A vibration simulator (R-3000; Mikrolar, NH, USA) was used to generate the
vibration exposure profiles. The vibration attenuation of the mat/boot/insole combinations were
determined by comparing the vibration below the heel and toe to the platform vibration (ADXL326
ultra-miniature tri-axial accelerometers attached to the underside of the foot at the heel and first
metatarsal, and to the platform). A baseline transmissibility measurement, with each participant
standing on the platform (B0M0I0=no boot, no mat, no insole) was also recorded at the beginning
and end of each experimental session. Ten healthy males participated in the experiment with a
mean age, height and mass of 30 +/-9 yrs, 1.8 +/-0.7m 85 +/-10kg, respectively. Each PPE
combination was evaluated using a 10 second vibration exposure period.
Results and Discussion
Preliminary findings suggest that most of the PPE combinations were effective at
controlling FTV entering the first metatarsal and heel at 3 Hz, and the heel at 30 Hz
(transmissibilities were below 1); however the PPE was not effective for limiting FTV entering
the first metatarsal at 30 Hz (Figure 1) or 40 Hz (data not presented due to space limitations). The
increased transmissibility at the heel and first metatarsal at 30 Hz (compared to 3Hz) may be due
to the low mass and unconstrained nature of the toes, which results in greater acceleration at the
37
toe than the heel. Furthermore the boots evaluated in this study all had a slight rocker that resulted
in the toe of the boot being raised above the platform surface. This shape may influence the weight
distribution between the baseline standing conditions and the PPE conditions. If the design of the
boot resulted in “un-weighting” at the first metatarsal then it could have contributed to the larger
transmissibility values recorded at the toe than the heel (Figure 1).
Future research will evaluate the best combination of PPE determined for 3 Hz, 30 Hz,
and 40 Hz in a field trial during operation of a locomotive, jumbo drill & bolter, and raise
platform respectively. If field trials are successful, the research team will partner with the mining
industry to disseminate information on the best combination of mat, boot, and insole products to
help reduce FTV exposures for mining workers.
References
1. Thompson, A., House, R., Krajnak, K., and Eger, T. (2010) Vibration-white foot: a case report. Occupational
Medicine 60: 572-574
2. Eger, T., Thompson, A., Leduc, M., Krajnak, K., Goggins, K., Godwin, A., and House, R. (2014) Vibration
induced white-feet: Overview and field study of vibration exposure and reported symptoms in workers. WORK:
A Journal of Prevention, Assessment & Rehabilitation 47(1): 101-110.
Figure 1: Measured FTV transmissibility from the platform through the PPE combinations to the underside of
heel (blue) and toe (red) at 3Hz dominant FTV exposure (top) and 30Hz FTV exposure (bottom) for 36
combinations of PPE and baseline (no PPE) at the beginning (B0M0I-Pre) and end of the trials (B0M0I0-post).
Note: The thick black line reflects a transmissibility value of 1 to help illustrate PPE combinations that resulted
in an attenuation of FTV (transmissibility values below 1).
38
TOOLS OF THE TRADE– MAINTENANCE OF WAY TOOLS ERGONOMIC AND
VIBRATION RISK ASSESSMENT
*Eckardt Johanning+, Paul Landsbergis++, Rick Inclima+++
+Columbia University, New York, USA ++SUNY Downstate School of Public Health, Brooklyn, NY, USA
+++Brotherhood of Maintenance of Way Employees Division of the International
Brotherhood of Teamsters, Washington, DC, USA
Introduction
There is a paucity of information regarding the occupational health and ergonomic risk of hand
tools contributing to hand-arm vibration (HAV) exposure among maintenance-of-way workers (MoW) in
the rail industry. MoW workers are building and maintaining tracks, bridges, buildings and other rail
structures used by the railroads in the USA. Track construction and repair involves unique and specialized
tools, machinery and vehicles in order to move rail and ties, pull or drive spikes, distribute ballast in order
to line, and surface and gauge railroad track. We have previously reported about typical MoW vehicles and
whole-body vibration measurements in road- and off-road vehicles.1 Anecdotal reports suggest that
musculoskeletal disorders of the upper extremities are common health complaints among the more than
35,000 MoW employees. As part of a larger study in cooperation with the union of the MoW workers
(BMWED) a pilot study with a needs assessment and review of typical hand tools used in the industry was
performed. Much of the newer equipment used by MoW workers are powered by gasoline or diesel engines,
electricity, air or hydraulics, nevertheless the work tasks are typically very physical and demanding,
involving known ergonomic risk factors, vibration and climate challenges. 2,3 Prolonged and intense
occupational whole-body vibration (WBV) as well as HAV have long been recognized as important
mechanical stressors contributing to early and accelerated degenerative joint diseases, neck and back pain,
prolapsed discs or injuries to the hand. 4 5 The goal of this investigation is to develop a trade-specific
research priority list of tools that merit further investigation, including detailed HAV measurements
according to international guidelines.
Methods
A literature review was performed utilizing Medline and other online resources with the search
terms: vibration, HAV, maintenance of way, track worker, and railroad. In addition, data was collected
through expert interviews and explorations with senior MoW workers and union health and safety
specialists about the tools that may cause HAV exposure and its typical application and uses in the trade.
Based on this information a preliminary priority list was developed to focus field investigations and HAV
measurements according to international guidelines.
Results and Discussion
A Medline search for MoW tools and related health problems resulted in zero returns. Expert
interviews of workers and listings in trade publications described the following typical tools in the trade.
Hand tools without energized power source: Lining bar, anchor wrenches, ballast forks, claw bars, spike
maul (hammer), sledge hammer, track wrenches, rail fork (rail turner), tie tongs, rail tongs, and track jack. Hand tools with hydraulic, pneumatic , or gas/diesel powered: Tamping guns, spiking guns, rock and rail
drills, wrenches, grinders, impact tools, horizontal surface grinders, spike pullers and drivers, tampers and
rail saws, and gauging adzer.
39
Table 1: Trade specific maintenance-of-way tools with known vibration exposure
No Tool Manufacturer Use Power
Hand use /
coupling
Vibration
data
available*
Exposure
risk
estimates*
1 Jack hammers Various Generic air bi-manual Yes Yes
2 Rock Drills Various Generic air bi-manual Yes Yes
3
Concrete
vibrator Various Generic air bi-manual Yes Yes
4 Hammer Drill Hilti Generic electric Dominant Yes Yes
5 Nail gun Hilti Generic electric Dominant Yes Yes
6
Reciprocating
saw Hilti Generic electric Dominant Yes Yes
7 Rivet buster Various MoW air Dominant unknown Unknown
8 Scabbler Various MoW air bi-manual unknown Unknown
9 Air hammer Various Generic electric Dominant Yes Yes
10 Impact wrench Various Generic air Dominant Yes Yes
11 Nut splitter Matweld MoW Bi-manual Yes Yes
12 Tamping gun Matweld MoW gas bi-manual Unknown Unknown
13 Profile grinder Various MoW gas bi-manual Unknown Unknown
14 Spike puller Matweld MoW Air bi-manual Unknown Unknown
15 Spiker guns Stanley MoW Hydraulic bi-manual Unknown Unknown
19 Spike driver Matweld Hydraulic bi-manual Unknown Unknown
16 Saws
Stanley
Geismar MoW
hydraulic
/ gas bi-manual Unknown Unknown
17 Impact tool Geismar MoW hydraulic bi-manual Unknown Unknown
18 Stone grinder Matweld MoW hydraulic bi-manual Unknown Unknown
19 Tamper Matweld MoW hydraulic Bi-manual Unknown Unknown
20 Rail drill Matweld MoW hydraulic bi-manual unknown Unknown * (http://www.portaleagentifisici.it/fo_hav_index.php?lg=EN) (https://las-bb.brandenburg.de/karla/recherche_outdoor.asp)
This pilot study showed that little to no information exists about possible ergonomic risks and HAV
exposure of hand tools that are typical and unique in the railroad Maintenance of Way trade. This
indicates a need for further research to aid in the prevention of musculoskeletal and HAV disorders
among track workers. We are seeking input from conference participants to refine this research protocol.
Literature
1. Johanning E. Vibration and shock exposure of maintenance-of-way vehicles in the railroad industry.
ApplErgon 2011;42:555-62.
2. Force JAT. Job Analysis Summary: Physical Demands and Environmental Conditions for the Job of
Section Laborer/Trackman. West Lafayette, Indiana1977 10 October 1977.
3. Barondess (Chair) JAeaP. Musculoskeletal Disorders and the Workplace. Low Back and Upper
Extremeties. Washington, D.C.: National Academy Press; 2001.
4. Bovenzi M. Health risks from occupational exposures to mechanical vibration. MedLav 2006;97:535-
41.
5. Pelmear PL, Leong D. Review of occupational standards and guidelines for hand-arm (segmental)
vibration syndrome (HAVS). Appl Occup Environ Hyg 2000;15:291-302.
40
REDUCTION OF THE VIBRATION TRANSMITTED TO THE HAND BY THE
CHISEL OF PNEUMATIC CHIPPING HAMMERS
Diego Scaccabarozzi, Bortolino Saggin and *Marco Tarabini
Politecnico di Milano, Department of Mechanical Engineering
Via Previati 1/C, 23900 Lecco, Italy
Introduction
Hand-arm vibration syndrome is caused by prolonged exposure to hand-arm vibration
(HAV)1. Hand-held power tools and hand-guided mechanical equipment are primary causes of
HAV, as testified by wide scientific community attention aimed to reduce vibration
transmissibility between the hand and the source of vibration2-5. Suspensions are generally added
in the tool design phase or adapt to existing devices with specifically-designed elements. One
common assumption of these approaches is that the vibration source can be modelled as ideal
vibration generation whose velocity is measured during actual working condition, i.e. without
considering the effect of the hand-arm impedance. Moreover, a dominant axis is generally studied
without considering in the suspension design possible axes interaction. Finally, the operator
variability is not accounted in the design phase, and the impedances defined in ISO 10068 are
commonly used. A more accurate approach was proposed in ref. [6] where a model was developed
accounting for the real characteristics of the vibration source and for the operator variability. The
model validity was demonstrated by designing an optimized suspension for a pneumatic chipping
hammer that allowed reducing the vibration level of 50%; this allowed exploiting the full working
time of 8 h without exceeding the daily limit exposure.
In this work, the optimization method developed in ref. [6] has been used to investigate the
design feasibility of a suspension system for the chisel of chipping pneumatic hammers. The need
of a suspension is well understood if one considers that the operators, while performing craftwork,
directly guide the chisel with one hand. The vibration levels are reduced only by the usage of
gloves for hand protection and by a “loose grip” allowing for the axial motion of the chisel. The
request is therefore to conceive a system that firmly grasped by the operator allows him to
accurately drive the chisel without reducing the tool effectiveness and at the same time reducing
the hand transmitted vibration.
Method
The model shown in Figure 1, based on the mobility approach, is the reference scheme for
the optimization process. The vibration source is modelled as ideal vibration generator with its
impedance Mg, represented mostly by the tool mass. The vibration velocity vg can be obtained
measuring the velocity at the hand-arm interface vh and the hand-arm operator impedance Mh.
The suspension system connects the generator to the hand-arm through impedances that are
represented by three terms, i.e. suspension mass Ms, stiffness Mk and damping Mc. Being the
generator characteristics known or measured, the velocity at the hand-arm interface can be
minimized with an optimal design of the suspension parameters. Thus, the suspension design is a
non-linear constrained optimization problem that can account for some specific technological
limitations and functional constraints for each studied case. In this work, design constraints are
summarized by the total suspension mass of 0.6 kg, by the radial static deflection of 10 mm under
a 40 N holding force and free sliding along the axial direction.
41
Results and Discussion
Experimental activity has been performed to measure the vibration levels on the chisel (Table 1).
Equivalent acceleration levels have been computed according to ISO 5349. Results evidenced an
equivalent vibration level ahw (about 13 m/s2)
well above the limit of 5 m/s2, therefore
confirming the need of a suspension system for
the operator hand. Two solutions have been
envisaged. In the first case, the chisel
suspension is axially linked to the hammer body
and the chisel can axially slide. The axial
suspension, in this case, has no stiffness but
only friction and the actual suspension is only
radial. In the second configuration, that is more
similar to the current handling mode (and so
preferred by the operators) the chisel suspension
is mounted on the chisel itself and an axial
stiffness is needed to keep its place. The two
optimal solutions share the radial parameters
while for the first the axial parameters are
nominally zero. Table 1 Measured vibration levels on the chisel
Table 2 shows the optimal scenario for the second
configuration. The adoption of the computed parameters
allows achieving an RMS acceleration level that is about
the half of the original value, with considerable
extension of the working time up to about 8 h per day.
Table 2 Suspension parameters deriving from the optimization
Mass [kg] Axial stiffness
[N/mm]
Radial stiffness
[N/mm]
Axial damping
coefficient
Radial damping
coefficient
ahw
[m/s2]
0.6 4 2 0.3 0.2 5.74
References
1. M.J. Griffin, Handbook of Human Vibration, Academic Press, 1996.
2. E.M. De Souza, T.N. Moore, Field performance evaluation of a rock drill handle design, Mining Engineering 45
(1993) 1402–1405.
3. K. Prajapati, P. Hes, Reduction of hand–arm transmitted vibration on pneumatic jackleg rock drills, CIM
Bulletin 94 (2001) 56–59.
4. R. Oddo, T. Loyau, P.E. Boileau, Y. Champoux, Design of a suspended handle to attenuate rock drill hand–arm
vibration: model development and validation, Journal of Sound and Vibration 275 (2004) 623–640.
5. B. Sam, K. Kathirvel, Development and evaluation of vibration isolators for reducing hand transmitted vibration
of walking and riding type power tillers, Biosystems Engineering 103 (2009) 427–437.
6. B. Saggin, D. Scaccabarozzi, M. Tarabini, Optimized design of suspension systems for hand–arm transmitted
vibration reduction, Journal of Sound and Vibration 331, (2012) 2671–2684.
Direction according to
ISO 10068
RMS acceleration
[m/s2]
yh 4.88
xh 6.81
zh 10.04
equivalent vibration generator
Mg
vg
suspension
operator
Mh
Mk
Mm
Mc
vh
Ms
vs
Figure 1 Proposed model for optimal suspension design
42
HAND-HELD IMPACT MACHINES WITH NONLINEARLY-TUNED VIBRATION
ABSORBER
*Hans Lindell, Viktor Berbyuk, Snævar Leó Grétarsson, Mattias Josefsson
*Swerea IVF, Box 104, 431 22, Mölndal, Sweden
Chalmers University of Technology, 412 96, Göteborg, Sweden
E-mails: [email protected], [email protected], [email protected], [email protected]
Introduction
Vibration exposure from hand-held impact machines (HHIM) such as rock drills, rammers and breakers with
a reciprocating action is a major cause for injuries to the workers in the industry. In order to improve the work
environment in the stone industry, a project was started with the objectives to redesign the tools to achieve low
vibration as well as improved ergonomics, dust removal and reduced noise while maintaining productivity1. Redesign
of current hand-held pneumatic impact machines can reduce the vibration level and thereby reduce injuries to workers.
Hand-arm vibration injury, often called Hand Arm Vibration Syndrome (HAVS) is one of the most common reasons
for work related injuries among this group of workers in the industry.
Although pneumatic impact machines have been used since the early 20th century little has been changed in
their fundamental design to date. Despite their being robust and efficient, vibration, noise, dust and poor ergonomics
cause a large number of injuries to the operators. Previous work has been done to reduce vibrations from these
machines of which some have been patented2,3. One approach is to use traditional linear tuned vibration absorbers
(TVA) invented in 1909 by Frahm and described by Den Hartog4. Although this technology is to a large extent limited
in practical use on this application due to it is only effective in a narrow frequency range. At higher frequencies the
TVA will instead increase the vibration and at lower frequencies will the effect rapidly decrease.
However, by introducing nonlinear spring characteristic of the absorber mass the effective frequency range
can be greatly increased and thereby can the technology be effectively implemented to this kind of machines5. As a
result a new generation of impact machines is developed by approaching the redesign from a user perspective, and
starting adhering to strict conditions of low vibration, noise and dust as well as sound ergonomics. The objective of
this study has therefore been to develop a user friendly low vibration impact machine using nonlinear tuned vibration
absorber together with integrated vibration isolation. A HHIM with a nonlinear tuned vibration absorber combined
with vibration isolation has shown to significantly reduce the vibration on the operator from 20 m/s2haw to a level close
to 2.5 m/s2haw.
Methods
The machine consists of a piston moving inside a cylinder hitting the working tool driven by compressed air.
The cylinder is in turn attached to a housing via vibration isolators. The operator handles are attached to the top of the
housing. An engineering model (E-model) of the HHIM in question is shown in Figure 1. The Nonlinear Tuned
Vibration Absorber (NTVA) comprises a mass which is moving along the machine restricted by a nonlinear stiffness.
The nonlinearity is in the simplest execution realized by introducing a gap between two springs and prestress in the
springs. From the E-model a mathematical model (M-model) is developed by setting up the equations of motion which
in turn is transformed to a computational model (C-model) realized in MATLAB code.
The vibration reduction of the HHIM was accomplished by using two combined approaches: 1) a NTVA was
designed that creates a counter force to the reaction forces on the cylinder of the piston and is effective in a broad
frequency range, and 2) vibration isolation between the impact mechanisms and the housing that the handles are
attached to. The isolation is applied in the axial, radial and rotational direction in order to further reduce the vibrations
that still remain from the piston and those from the chisel hitting the stone. Care has been taken not to compromise
the ability to accurately control the machine.
Results and Discussions
The C-model of the machine in question was verified both in a test rig and on a HHIM prototype and shows
sufficient correlation. The C-model has been used to simulate the machine vibration dynamics for different operational
scenarios. Sensitivity analysis of the vibration dynamics has been done with respect to system structural parameters.
It was found that vibration dynamics is strongly sensitive to variation of the values of gap, stiffness and spring’s
43
prestress of the NTVA, and is subject to optimization. The optimization problem has been stated and solved
numerically. Figure 2 shows the vibration reduction effect for different scenarios. Line A is the vibration from a
traditional machine with m, M and MH fixed. Line B is from a machine with vibration isolation between M and MH.
Line C is a traditional TVA and finally Line D is the vibration from an optimized NTVA. Due to variations in machine
load, spread in production etc which leads to variations in operating frequency is the expected operating range between
23 and 33 Hz.
What can be found is that the average vibration reduction from the original machine in the operating range
is estimated to be 95% for the NTVA plus vibration isolation (Line D), 50% for only vibration isolation (Line B).
Finally the linear TVA plus vibration isolation is about 60% which is just slightly more than with only the vibration
isolation but with very high frequency dependence.
Figure 2 E-model of HHIM with NTVA Figure 2 Vibration at machine handle from C-model
The project has built several prototype machines which have been field tested with good results and a small
scale production is planned. In addition to the low vibration also other improvements have been measured and
observed: feed force from the operator is more than halved, weight of the machine is halved, sound power is reduced
by >10 dBA, increased efficiency, longer tool life, improved dust extraction and finally greatly improved ergonomics
with adjustable handle length. The conclusion is that the concept with NTVA and potentially with a vibration isolation
can greatly reduce vibration exposure from machines with reciprocating vibrations in a very cost efficient manner.
References
1. Lindell H. (2011) Redesign of hand-held impact machines to reduce hand-arm vibration, Twelfth International
Conference on Hand-Arm Vibration, Ottawa, Canada, June 13 – 17, 80 – 81.
2. Moessnang F. US Patent US7712548B2
3. Henriksson S. Ostensson O. US Patent US20080073095A1
4. Den Hartog, J. P. (1985) Mechanical Vibrations, New York, Dower Publication, Inc
5. Lindell H. Patent WO 2014/095936 A1
Acknowledgements: This project was funded by AFA Insurance, AP Sten, Benders and Emmaboda Granit. A
special thanks to Bert Andersson, TM Verkstad for manufacturing prototypes.
0
0,2
0,4
0,6
0,8
1
1,2
1,4
1,6
10 15 20 25 30 35 40
Dis
pla
cem
en
t [m
m r
ms]
Piston frequency [Hz]
Vibration at handle
A: No vib. isol. B: Fixed counter mass C: Linear TVA D: Nonlinear TVA
Expected operating range
m
c1
c2
k1
k2
a
az(t)
zM(t)
mp
kh/2ch/2 kh/2
ch/2
z
Fc(t)
P
M
kHcH
MH
zH(t)
kMcM
44
THE EFFECT OF A MECHANICAL ARM TOOL SUPPORT SYSTEM ON
WORKPLACE GRINDER VIBRATIONS
Thomas W. McDowell, Daniel E. Welcome, Christopher Warren,
Xueyan S. Xu, *Ren G. Dong
Engineering and Control Technology Branch, Health Effects Laboratory Division,
National Institute for Occupational Safety & Health, Morgantown, WV, USA
Introduction
Repetitive powered hand tool operations requiring high forces have been associated with
workplace musculoskeletal disorders, especially in the lower back and upper limbs.(1, 2) In efforts
to alleviate some of the stressors associated with such tool operations, and to increase productivity,
the US Department of Defense has been evaluating the use of counter-balanced mechanical arms
to support tools such as sanders, grinders, and large drills during overhead and other stressful
operations at large US Navy shipyards and US Air Force aircraft maintenance facilities. However,
the use of this intervention can significantly increase the daily time on task, which in turn increases
the time that tool operators are exposed to other potentially harmful agents such as respirable dust,
noise, and hand-transmitted vibration (HTV). The effect of the mechanical arms on tool vibration
emissions is unknown. To begin to address this knowledge gap, the purpose of this study was to
assess tool handle vibrations of pneumatic grinders as they were operated during typical shipyard
grinding tasks with and without the support of a mechanical arm system.
Methods
Four new pneumatic grinders were used in the evaluations (Table 1). Each grinder/wheel
combination weighed about 6 kg. The mechanical arm used to support the grinders was an
Equipois® zeroG4 arm mounted on a mobile Equipois UMS Quad Stand (see Fig. 1). This arm is
designed to support loads up to about 19 kg. At a large US Navy shipyard, four grinder operators
used the tools to complete surface grinding tasks on mild steel. One workstation involved vertical
grinding with the steel surface at about shoulder height, while the second work task involved
horizontal grinding (pictured in Fig. 1).
Frequency-weighted and unweighted tri-axial
acceleration data were collected at both tool handles
in accordance with ISO 5349-1 (2001)(3) as each
operator completed five consecutive 10-second data
collection trials with each tool/support
condition/workstation combination (5×4×2×2 = 80
trials per operator). Grinding wheels were discarded
and replaced with brand new ones after each 5-trial
data collection period.
Tool Make Model Wheel Type
A Ingersoll-Rand 88V60S106 6" flared cup
B Atlas Copco GTG40 S060-927 9" disk
C Ingersoll-Rand 99V60P109 9" disk
D Honsa HTVG 36 6" flared cup
Fig. 1. Tool handle vibrations are recorded as an
operator performs the horizontal grinding task
with Tool B supported by the mechanical arm.
The left handle was used as the arm system
attachment point for each tool.
Table 1. Descriptions of the grinders used in the
evaluations along with the grinding wheel types.
45
Results and Conclusions
The average measured acceleration was
slightly higher at the left tool handle than the right
handle for all four grinders. Acceleration averages
for the vertical and horizontal grinding tasks were
not statistically different.
Each grinder’s average one-third octave band
frequency spectra measured at the left tool handle
while the operators performed the horizontal
grinding task are shown in Fig. 2. Frequency-
weighted and unweighted acceleration averages for
both grinding tasks under both support conditions
are presented in Table 2. As indicated in the figure
and table, the use of the Equipois mechanical arm
support did not substantially affect the grinder
handle vibrations. In most cases, the average
acceleration was reduced somewhat with the use of
the mechanical arm system, but in general, the
vibration was not effectively attenuated by this
intervention. These results indicate that while the
use of the mechanical arm can reduce some of the stressors associated with the operations of heavy
powered hand tools, the increased time on task afforded by the system would likely increase daily
time-weighted HTV exposures. This apparent trade-off needs further examination.
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, NIOSH Publication 97-
141. Cincinnati, OH: U.S. Department of Health and Human Services, National Institute for Occupational Safety
and Health; 1997.
2. Chourasia AO, Sesto ME, Block WF, Radwin RG. Prolonged mechanical and physiological changes in the upper
extremity following short-term simulated power hand tool use. Ergonomics. 2009;52(1):15-24.
3. ISO 5349-1: Mechanical Vibration -- Measurement and Evaluation of Human Exposure to Hand-Transmitted
Vibration -- Part 1: General Requirements. Geneva: International Organization for Standardization, 2001.
0.10
1.00
10.00
100.00
1 10 100 1000 10000
Un
we
igh
ted
Acc
ele
rati
on
(m
/s2)
Frequency (Hz)
A
B
C
D
Tool
Condition: UnsupportedTask: Horizontal grinding
0.10
1.00
10.00
100.00
1 10 100 1000 10000
Un
we
igh
ted
Acc
ele
rati
on
(m
/s2)
Frequency (Hz)
A
B
C
D
Tool
Condition: SupportedTask: Horizontal grinding
Fig. 2. The average one-third octave-band frequency spectra for each of the four tools used in the
horizontal grinding task in the (a) unsupported condition and (b) the supported condition.
Table 2. The unweighted and frequency-
weighted acceleration averages for the left
handle of each grinder in both support
conditions for each workstation.
(a) (b)
Workstation 1 (vertical grinding)
Unweighted Weighted Unweighted Weighted
Tool (m/s2) (m/s
2) (m/s
2) (m/s
2)
A 130.9 5.1 122.3 4.5
B 134.9 5.6 190.0 5.7
C 106.9 3.0 87.1 3.2
D 91.1 8.0 61.5 4.7
Workstation 2 (horizontal grinding)
Unweighted Weighted Unweighted Weighted
Tool (m/s2) (m/s
2) (m/s
2) (m/s
2)
A 153.6 6.6 91.7 4.6
B 148.7 6.5 142.5 4.6
C 111.8 2.6 108.7 2.8
D 92.8 8.2 59.3 4.4
Unsupported Supported
Unsupported Supported
46
Poster Session
Chairs: Qingsong Chen and Ren G. Dong
Presenter Title and authors Page
Qingsong Chen A preliminary investigation on the factors influencing the
vibration of a handheld workpiece during its fine
polishing process
Hansheng Lin, Guiping Chen, Shichuan Tang, Bin Xiao,
Guoyong Xu, Maosheng Yan, Hua Yan, Qingsong Chen
47
Qingsong Chen Plasma biomarkers of peripheral vascular damage in
workers exposed to hand-transmitted vibration - a case-
control study
Qingsong Chen, Fansong Zeng, Li Lang, Shichuan Tang,
Bin Xiao, Aichu Yang, Hansheng Lin, Hanlin Huang
49
Qingsong Chen Serum proteomic analysis among workers with hand-arm
vibration syndrome
Maosheng Yan, Danying Zhang, Fansong Zeng, Bin
Xiao, Li Lang, Hongling Li, Guiping Chen, Qingsong
Chen
51
47
A PRELIMINARY INVESTION ON THE FACTORS INFLUENCING THE VIBRATION
OF A HANDHELD WORKPIECE DURING ITS FINE POLISHING PROCESS
Hansheng Lin+, Guiping Chen+, Shichuan Tang++, Bin Xiao+, Guoyong Xu+,
Maosheng Yan+, Hua Yan+, *Qingsong Chen+ +Guangdong Province Hospital for Occupational Disease Prevention and Treatment, Guangdong
Provincial Key Laboratory of Occupational Disease Prevention and Treatment, Guangzhou,
Guangdong 510300, China; ++Key Laboratory of Occupational Health and Safety, Beijing Municipal Institute of Labor
Protection, Beijing, China Correspondence author: [email protected]
Introduction
Fine grinding or polishing of handheld workpieces can be found in labor-intensive hardware
manufacturers for making sport equipment, tools, etc. The grinding or polishing processes are characterized
by prolonged and intensive exposure to fingers-transmitted or hand-transmitted vibration. Such vibration
exposure has resulted in a significant prevalence (> 15%) of vibration-induced disorders among workers
performing the grinding and polishing tasks1. Preliminary observations suggest that the rotational speed of
the grinding or polishing machine, its seat cushion, and the type of grinding or polishing wheel are among
the major factors that influence the vibration exposure of the workers during the operations. However, their
exact effects have not been sufficiently identified and understood. This study aimed to further verify and
understand these influencing factors by examining a typical polishing operation and to explore methods for
improving the operation conditions in order to reduce the vibration exposure among the workers.
Method
A fine polishing process of golf club head was simulated in this study, which is shown in Figure 1.
A single-head polishing machine was used in the simulation. To avoid the effect of any human subject on
the vibration of the golf club head, a pneumatic device was specially designed, built, and used to push the
golf club head to the polishing wheel with a constant push force (9.8 N) to simulate the polishing process.
An acceleration measuring probe of a portable human vibration analyzer (SV106) was inserted into the golf
club head. The head was then attached to the pneumatic pushing device and pushed against the polishing
wheel in the experiment. To examine the effect of the rotation speed of the polishing machine on the
workpiece vibration, three rotation speeds (1200 r/min, 1800 r/min, 2400 r/min) were tested on the original
setup of the polishing machine used in the gold equipment manufacturer. To examine the effect of the seat
cushion of the polishing machine on the vibration, two types of seat cushions (ordinary plastic mat and
high-elastic rubber mat, Figure 2) were installed at the bottom of the grinding machine and used in the test
under the same grinder speed (2400 r/min). Two types of polishing wheels (certified polishing wheel,
uncertified polishing wheel, Figure 3) were also tested under the same speed (2400 r/min) to examine the
effect of the polishing wheel. The vibration analyzer directly measures the frequency-weighted acceleration
defined in ISO 5349-1 (2001)2. An ANOVA was performed to determine the significance of the effects.
Independent sample t-tests were also performed to examine the significance of the vibration differences.
Results and Discussions
For the ordinary plastic mats at the three speed levels (1200 r/min, 1800 r/min, and 2400 r/min), the
weighted accelerations ( X S ) were 0.86±0.04 m/s2, 1.12 ±0.04 m/s2, and 1.84 ± 0.05 m/s2, respectively,
and they were significantly different (p <0.05). The data indicates that increasing the rotational speed
substantially increased the weighted acceleration. This is likely because the polishing wheel is not fully
balanced and the inertial vibrating force of the unbalanced mass theoretically increases approximately with
the square of the rotation speed. At 2400 r/min, the acceleration with the high elastic rubber (1.35±0.05
m/s2) was significantly lower than that with the ordinary plastic mats (1.84±0.05m/s2; p <0.05). This
suggests that the suspension of the polishing machine is likely to play a certain role in the vibration response
of the system. With the ordinary plastic mats at 2400 r/min, the vibration acceleration with an uncertified
48
polishing wheel (2.37±0.07 m/s2) was significantly higher than that of certified polishing wheel (1.84±0.05
m/s2; p<0.05). This suggests that it is better to avoid using the uncertified polishing wheel in the operation.
These findings indicate that the vibration exposure of the workers in such a polishing process can be reduced
by improving the design and maintenance of the polishing machine and the use of a better polishing wheel.
References
1. Qingsong Chen, Bin Xiao, Aichu Yang, Hansheng Lin, Hua Yan, Li Lang, Maosheng Yan, Guiping
Chen, Fansong Zeng, Xuqing Cao. The characteristics of vibration-induced white finger in workers
polishing handheld pieces in the southern subtropics of china. Proceedings of the 13th International
Conference on Hand-Arm Vibration, Beijing, China, October 2015.
2. International Organization for Standardization (2001) ISO5349-1. Mechanical vibration and shock —
Measurement and evaluation of human exposure to hand-transmitted vibration —Part 1: General
requirements.
Figure 2: Ordinary plastic mat (left) and high elastic
rubber mat (right)
Figure 3: Certified polishing wheel (left) and
uncertified polishing wheel (right)
49
PLASMA BIOMARKERS OF PERIPHERAL VASCULAR DAMAGE IN WORKERS
EXPOSED TO HAND-TRANSMITTED VIBRATION - A CASE-CONTROL STUDY
*Qingsong Chen+, Fansong Zeng+, Li Lang+, Shichuan Tang++, Bin Xiao+,
Aichu Yang+, Hansheng Lin+, Hanlin Huang+
+Guangdong Province Hospital for Occupational Disease Prevention and Treatment
Guangdong Provincial Key Laboratory of Occupational Disease Prevention and Treatment,
Guangzhou, Guangdong 510300, China ++Key Laboratory of Occupational Health and Safety, Beijing Municipal Institute of Labor
Protection, Beijing, China
Correspondence to: [email protected]
Introduction
A lack of sensitive, specific, and objective indicators exist for diagnosing and staging peripheral
vascular damage related to hand-arm vibration syndrome (HAVS). Results of previous studies
demonstrated that serotonin (5-HT), endothelin-1 (ET-1), soluble intercellular adhesion
molecule-1 (sICAM-1), and transforming growth factor beta 1 (TGF-β1) played significant roles
in the pathogenesis of vascular disease. The current study investigates whether these factors
could be applied in the diagnosis of peripheral vascular damage due to HAVS.
Methods
In our study, 43 male workers with vibration-induced white finger (VWF) and 44male workers
without VWF who were exposed to hand-transmitted vibration from thesame metal work factory
were selected as cases and controls, respectively. Plasma 5-HT, ET-1, TGF-β1, and sICAM-1 levels
were determined by enzyme-linked immunosorbent assay in these groups. Differences were also
assessed according to whether workers were exposed to high vs low vibration.
Results and Discussions
5-HT, ET-1, and TGF-β1 levels between VWF and No-VWF groups were significantly different
(p<0.05, p<0.001, and p<0.01, respectively), even after accounting forage, and smoking and
drinking statuses (p<0.05, p<0.001, and p<0.05, respectively). According to ROC analysis and
diagnostic tests, plasma ET-1 and TGF-β1were determined to be apposite parameters for predicting
VWF and vascular injury (cut-off value: 47.55 pg/mL, AUC: 0.760 [0.649–0.871], p<0.001; cut-
off value: 1.75 ng/mL AUC: 0.691 [0.573–0.808], p<0.01, respectively). In contrast with workers
exposed to low vibration, the average plasma 5-HT, ET-1, sICAM-1, and TGF-β1 levels were
elevated in those exposed to high vibration. These differences were statistically significant
(p<0.05), with the exception of sICAM-1. So, Plasma ET-1 and TGF-β1 seem to be sufficient
indicators in the diagnosis of peripheral vessel damage due to HAVS.
50
Figure 1: ROC analysis of variables
References
1. Grześk G, Szadujkis-Szadurska K, Matusiak G, Malinowski B, Gajdus M, Wiciński M,
Szadujkis-Szadurski L. Influence of celecoxib on the vasodilating properties of human
mesenteric arteries constricted with endothelin-1. Biomed Rep, 2014. 2(3): 412-418.
2. Yammine L, Kang DH, Baun MM, Meininger JC. Endothelin-1 and psychosocial risk factors
for cardiovascular disease: a systematic review. Psychosomatic medicine, 2014. 76(2):109-
121.
3. Lev PR, Salim JP, Marta RF, Osorio MJ, Goette NP, Molinas FC. Platelets possess functional
TGF-beta receptors and Smad2 protein. Platelets, 2007. 18(1): p. 35-42.
4. Liu Y, Tian H, Yan X, Fan F, Wang W, Han J. Serotonin inhibits apoptosis of pulmonary artery
smooth muscle cells through 5-HT2A receptors involved in the pulmonary artery remodeling
of pulmonary artery hypertension. Exp Lung Res, 2013. 39(2): 70-79.
5. Kennedy G, Khan F, McLaren M, Belch JJ. Endothelial activation and response in patients
with hand arm vibration syndrome. Eur J Clin Invest, 1999. 29(7): 577-581.
51
SERUM PROTEOMIC ANALYSIS IN WORKERS WITH
HAND-ARM VIBRATION SYNDROME
Maosheng Yan, Danying Zhang, Fansong Zeng,
Bin Xiao, Li Lang, Hongling Li, Guiping Chen, *Qingsong Chen
Guangdong Province Hospital for Occupational Disease Prevention and Treatment;
Guangdong Provincial Key Laboratory of Occupational Disease Prevention and Treatment,
Guangzhou, Guangdong 510300, China *Correspondence to: [email protected]
Introduction
Hand-Arm Vibration Syndrome (HAVS), a secondary form of Raynaud’s disease, is induced
by hand-transmitted vibration amongst industrial workers1. To date, the pathogenesis of this
disease is still not completely understood; however, dysregulation of autonomic and intravascular
alterations (such as platelet activation, oxidative stress, and leukocyte hyper-activation) have been
observed2.It was previously demonstrated that the serum levels of several proteins were
significantly different in patients with HAVS3. The aim of this work was to evaluate protein
expression changes in the serum of HAVS patients.
Methods
We used quantitative iTRAQ LC-MS/MS analysis to identify proteins that were differentially
expressed in the serum of a non-vibration-exposed control group (NVEC), a vibration-exposed
group(VEC), and a HAVS patient group (HAVS). The latter group was subdivided into two disease
severity groups (mild and severe). Eight serum samples were pooled for determination in every
group. A multivariate logistic regression analysis was used to identify predictive biomarkers.
Results
In total, compared with the NVEC group, 74 differentially expressed proteins were identified
in the VEC and HAVS groups (Fig1 a). Of these, 40 proteins were under expressed and 34 were
over expressed in the VEC and HAVS groups. Compared with the VEC group, 80 differentially
expressed proteins were identified in the HAVS group (Fig1 b). In addition, 80 differentially
expressed proteins were identified between the VEC and HAVS groups (Fig1 b). Of these, 55
proteins were under expressed and 25 were over expressed in the HAVS group. A bioinformatics
analysis of the differentially expressed proteins demonstrated that they participated in various
biological processes, and focal adhesion pathways was one of the major Kyoto Encyclopedia of
Genes and Genomes (KEGG) pathways(Fig 2).
Discussion
Taken together, using a proteomic approach, our findings suggest that, compared with those
not exposed, differential protein expression occurs in the serum of workers exposed to vibrations.
The expression of numerous proteins varies by disease severity and these differentially expressed
proteins are potential serum biomarkers for HAVS. Finally, focal adhesion was one of the major
pathways identified in the pathogenesis of the HAVS4.
52
References
1. Bovenzi M. Exposure-response relationship in the hand-arm vibration syndrome: an overview of current
epidemiology research. Int Arch Occup Environ Health. 1998, 71(8):509-519.
2. Herrick AL. Pathogenesis of Raynaud's phenomenon. Rheumatology (Oxford). 2005, 44(5):587-596.
3. Kohout J, Topolcan O, Bejckova H. The serum level of endothelin in patients with hand-arm vibration
syndrome. Cent Eur J Public Health. 1995, 3 Suppl:43-44.
4. Ho YY, Lagares D, Tager AM, Kapoor M. Fibrosis--a lethal component of systemic sclerosis. Nat Rev
Rheumatol. 2014, 10(7):390-402.
Fig 1. Protein ratio distribution. (A) Healthy control groups vs exposed and HAVS patient groups; (B)
Exposed groups vs HAVS patient groups.
Fig 2. Bioinformatic analysis of differentially expressed proteins demonstrating that focal
adhesion was one of the major pathways involved.
A B under expressed
over expressed
under expressed
over expressed
53
Session V: Characterization of Biodynamic Responses
Chair: Sven Matthiesen and John Z. Wu
Presenter Title and authors Page
Xueyan S. Xu A preliminary investigation on the vibration
transmissibility at the shoulder and neck
Xueyan S. Xu, Daniel E. Welcome, Christopher Warren,
Thomas W. McDowell, John Z. Wu, Ren G. Dong
54
Xueyan S. Xu Mechanical shock transmission through the hand-arm
system to the shoulder, back, head and neck
Daniel E. Welcome, Xueyan S. Xu, Christopher Warren,
Thomas W. McDowell, John Z. Wu, Ren G. Dong
56
Christophe Noël Development and use of an experimental device
including a laser scanning vibrometer for measuring the
vibration transmissibility mapping on the dorsum of
hands gripping a vibrating handle
Christophe Noël
58
Enrico Marchetti Hand-arm vibration transmissibility measurement for
assessing hearing impairment
Enrico Marchetti, Renata Sisto, Alessandro Lunghi,
Floriana Sacco, Filippo Sanjust, Raoul Di Giovanni,
Teresa Botti, Angelo Tirabasso
60
Almaky Almagirby A new methodology for measuring vibration
transmissibility on a gripped handle for HAVS research
Almaky Almagirby, Matt J. Carré, Jem A. Rongong
62
Marco Tarabini Nonlinearities in the biodynamic response of the hand-
arm system to single-axis vibration
Marco Tarabini, Lan Xie, Bortolino Saggin, Diego
Scaccabarozzi
64
54
A PRELIMIRAY INVESTIGATION ON THE VIBRATION TRANSMISSIBILITY
AT THE SHOULDER AND NECK
*Xueyan S. Xu, Daniel E. Welcome, Christopher Warren,
Thomas W. McDowell, John Z. Wu, Ren G. Dong
Engineering and Control Technology Branch, Health Effects Laboratory Division,
National Institute for Occupational Safety & Health, Morgantown, WV, USA
Introduction
Although the association between vibration exposure and musculoskeletal disorders (MSDs)
in the shoulder and neck was reported in some studies1,2, it remains unclear whether and how the
vibration exposure can directly or indirectly affect the development of the shoulder and neck
MSDs. To have a direct influence, substantial vibration would have to be transmitted to the
shoulder and neck. This may happen in the operations of some low-frequency (<25 Hz) tools such
as vibrating forks, sand rammers, and road breakers. However, it remains unclear exactly how
much vibration can be effectively transmitted to the shoulder and neck from the handle-hand
interface. As the first step to enhance the understanding of the vibration effects on the shoulder
and neck MSDs, this study investigated the vibration transmissibility on the shoulder and neck.
Methods
Eight adult subjects participated in the study. As shown in Fig. 1, the experiment was carried
out on a 1-D vibration test system. Each subject used both hands to grip and push on the handles
fixed on the test system. A broadband random vibration from 4 to 100 Hz was used as the
excitation. The vibration transmissibility frequency spectra were measured on the skin at five
locations distributed on the upper arm, shoulder, and neck using a scanning laser vibrometer
(Polytec, 3-D scanning laser). The independent variables include total push force (50 N, 75 N, 100
N) and elbow bending angle (90º, 120º). Apparent mass at the palm of the hand was also measured.
Fig. 1. A pictorial view of the subject test and measurement locations
Results and Discussions
Example results for one specific push/grip force and arm posture are shown in Fig. 2, which
displays the vibration transmissibility spectra of 8 subjects at the 5 locations, as well as apparent
1
2 3 4
5
1
2 3
4
5 Laser 1-D shaker
Symmetric
handles
55
mass. As expected, the vibration transmissibility decreased with the increased distance from the
vibrating source. Not much vibration was transmitted to the neck and back, with the maximum
transmissibility of less than 0.3 (P1 to P3). Vibration transmitted to the back surface of the shoulder
(P4) was slightly higher, with a peak of less than 0.5, except that measured with one of the subjects.
The highest transmissibility was observed in the spectra measured on the upper arm (P5), with a
mean peak magnitude of 1.33 at 8 Hz. The peak frequency in the apparent mass spectrum was
generally correlated with that of the vibration transmissibility measured on the upper arm. The
peak frequency of the mean apparent mass function was also 8 Hz. Subject differences are
obviously shown in both transmissibility and apparent mass.
Low-frequency tools can generate significant vibrations usually in the range of 5 to 25 Hz.
The results of this study indicate that such vibrations can be effectively transmitted to and amplifed
on the upper arm. A lesser portion of the vibration can be transmitted to the shoulder and neck.
The correlation between the transmissibility and apparent mass is consistent with their theoretical
relationship3.
Frequency (Hz)
Fig. 2. Averaged vibration transmissibility spectra and apparent mass of each subject
References
1. Van der Windt D.A., Thomas E., Pope D.P., et al. Occupational risk factors for shoulder pain: a systematic review.
Occupational and Environmental Medicine, 57 (7) (2000), pp. 433–442
2. Ariens G.A., Van Mechelen W., Bongers P.M., et al. Physical risk factors for neck pain. Scandinavian Journal of
Work, Environment and Health, 26 (1) (2000): 7–19.
3. Dong RG, Welcome DE, McDowell TW, Wu JZ. Theoretical relationship between vibration transmissibility and
driving-point response functions of the human body. Journal of Sound and Vibration. 332 (2013): 6193-202.
Apparent Mass
P5 P4
Tra
nsm
issi
bil
ity
in
vib
rati
on
dir
ecti
on
P1 P2 P3
56
MECHANICAL SHOCK TRANSMISSION THROUGH
THE HAND-ARM SYSTEM TO THE SHOULDER, BACK, HEAD AND NECK
Daniel E. Welcome, *Xueyan S. Xu, Christopher Warren,
Thomas W. McDowell, John Z. Wu, Ren G. Dong
Engineering and Control Technology Branch, Health Effects Laboratory Division,
National Institute for Occupational Safety & Health, Morgantown, WV, USA
Introduction
Impulsive tools such as road breakers, stone hammers, and chipping hammers are used at
some workplaces. The mechanical shocks generated on such tools may be transmitted to hands,
arms, shoulders, back, neck, and head of the tool operators. Prolonged exposure to the shocks,
combined with a forceful exertion during the tool operation, may cause injuries and disorders in
these substructures of the human body. While considerable work has been done to characterize the
response of the hand-arm system to random broadband vibration, limited investigation has been
done on the transmission of the shocks in the upper extremities of the human body1. To help
understand the shock-induced injuries and disorders, the objective of this study is to investigate
the propagation of the mechanical shocks in the upper extremities.
Methods
The study was conducted on a 1-D hand-arm vibration test system, as shown in Figure 1. Eight
adult subjects - six males and two females - participated in the experiment. Each subject used both
hands to grip (10N each hand) and push (75N total) on dual instrumented handles fixed on the test
system; the push force was also measured with a force plate. The subjects pushed with an elbow
posture of 120º as shown in the Figure. Half sine mechanical shocks with a duration of 15ms and
magnitude of 5g were used for the exposure. The shock responses in time history were measured
on retro-reflective tape on the skin at five locations distributed on the upper arm, shoulder, back,
and neck using a 3D scanning laser vibrometer (Polytec, PSV-500) and using accelerometer
instrumented adapters wrapped on each wrist and the forehead with signals acquired via B&K
Pulse. The laser vibrometer and adapter measurements were synchronously referenced to the input
acceleration at the shaker handle
assembly. A sequence of seven shocks,
with four seconds between each shock,
was input and the laser focused on a single
measurement point for each trial. Two
trials were taken for each test treatment.
The last five shocks in each trial were used
in the data analysis. The peak magnitudes
over the five shocks were identified and
averaged. Then, the peak ratio was
calculated by dividing the mean peak with
the input peak measured on the handle.
Fig. 1. Subject postures and measurement locations.
X
1
4
2 3
Wrist Adapter
Y
Z
57
Preliminary Results and Discussions
As examples, the input shock and the time-domain responses measured in the Z direction at the
eight locations are shown in Figure 2. Table 1 lists the mean peak ratios of the eight subjects
measured at the eight locations, which were calculated using the vector sum of the time-history
responses in the three orthogonal directions shown in Figure 1. As shown in the Figure and Table,
the shock responses generally decrease with the increase in the distance from the shock input point.
As the input shock from the handle was along the z direction, the response was also the greatest
along the z axis of the wrists, arm, shoulder, and back. However, the response was more prominent
in the vertical or Y direction for the head. This suggests that the shock input resulted in significant
rotational response of the head, which explains why there is substantial cross-axis response in the
Y direction. As also shown in Table 1, the coefficient of variation at each location was high among
the subjects. This suggests that the shock transmission in the upper extremities is individual-
specific.
Fig.2. Input shock from the handle and the responses at eight measurement
Table 1. The average peak ratios (of the eight subjects at eight measurement locations
Right Wrist Left Wrist Upper Arm Shoulder Left Back Right Back Neck Head
0.949 0.984 0.412 0.116 0.055 0.066 0.061 0.060
STD 0.186 0.120 0.158 0.039 0.017 0.020 0.014 0.015
CoV 0.20 0.12 0.38 0.34 0.30 0.30 0.23 0.26
References
1. Pope MH, Magnusson M, Hansson T. 1997. The upper extremity attenuates intermediate frequency vibrations.
J. Biomechanics. 30(2): 103-108.
Left Wrist
Acc
eler
ati
on
(m
/s2) Input Right Wrist
Shoulder Upper Arm Right Back
0 0.5 0 0.5 0 0.5
Time (s)
Head Neck Left Back
58
DEVELOPMENT AND USE OF AN EXPERIMENTAL DEVICE INCLUDING A LASER SCANNING
VIBROMETER FOR MEASURING THE VIBRATION TRANSMISSIBILITY MAPPING ON THE
DORSUM OF HANDS GRIPPING A VIBRATING HANDLE
*Christophe Noël
Laboratoire de Modélisation des Systèmes Mécaniques de Prévention
Institut national de recherche et de sécurité (INRS)
1 rue du Morvan - CS 60027 - F-54519 VANDOEUVRE cedex,France
Introduction
Many experimental studies have been carried out by different research laboratories in order to assess the
biodynamic response of the upper limb exposed to vibrations.1 Indeed, this response provides a way to characterise
the changes of the mechanical stress and strain field occurring during the propagation of vibration and it has been
suggested that such modifications are likely to be responsible for the onset of hand-arm vibration syndrome.1 Previous
works succeeded in quantifying the influence of several factors like posture, push and grip forces on the dynamic
response of Hand-Arm system. Most of these measurements like for example the driving point mechanical impedance,
lead to evaluate the global behaviour of the upper limb. We propose in the following study to describe an original
experimental device for assessing the acceleration by using a scanning vibrometer2-3 at selected points of a measuring
mesh projected on the back of hand. Thus, we can estimate local dynamic responses, for instance expressed in terms
of acceleration transmissibility maps and then extract more accurate information from the spatial characteristics of the
vibration.4 Then, the method was implemented to analyse the effect of various parameters on the acceleration transfer
between a vibrating handle and the back of hand. Push and grip forces, postures, ambient temperature, handle
acceleration have been varied and the attenuation ability of antivibration glove materials have also been tested, but
only a few findings will be presented in this paper.
Methods
The overview of the experimental device is shown on Fig. 1(a). We developed a dedicated software to drive
the laser beam moved by two motorized mirrors and to set some laser parameters at the same time. Data were measured
with an acquisition unit plugged to a central laptop which moves the spot and triggers the measurement. This software
computes and projects the measurement mesh (around 100 nodes) directly onto the dorsum of the hand. For ensuring
a uniform acceleration in the contact area between the hand and the handle, the latter was designed so that its first
eigenfrequency was located far below the frequency band of interest. The handle sketched in Fig. 1(b), was
instrumented with sensors for measuring both static and dynamic push and grip forces and also with an accelerometer.
It was mounted on an electrodynamic shaker with a flat frequency response up to 800Hz. The screw connections were
minimized to increase the signal/noise ratio and so to improve the spectral coherence in high frequency. Moreover, in
order to ensure enough back-scattering laser light power, we covered the skin with a mix of glass micro beads and
body painting. This way was more convenient and effective than using common reflective tapes. Regarding
experimental protocol, the transmissibility maps were measured by third octave bands for 20 subjects aged from 18 to
39 and for 16 pairs of coupling forces defined as a percentage (5% to 50%) of the individual maximum static push
and grip effort. The posture is shown on Fig. 1(c). The handle acceleration spectral content was a broadband noise in
the frequency range [25Hz-500Hz] with a rms value of 15 m.s-2 (not ISO 5349 weighting). An inverse method using
the transfer function between the shaker electrical input and the handle acceleration was implemented to keep this
value constant for every subject and coupling forces.
Fig. 1: Experimental setup (a), instrumented handle with main dimensions (b) and posture selected in this paper (c)
(a) (c) (b)
59
Results and Discussions
Two different approaches are considered to process the measurements. In the first approach the raw
transmissibility maps of every subject were analyzed to find out common trends. In the second approach, we used a
mathematical metrics (for example the geometric spatial average or the spatial spread/dispersion) in order to contract
the spatial information in a scalar and then perform statistical analysis. We present here only typical raw
transmissibility maps which highlight the influence of the parameters considered but all the conclusions drawn below
rely on a statistical study. The effect of the handle excitation frequency is illustrated on Fig. 2 for one particular subject
pushing and gripping the handle with a force respectively of 30% and 15% relative to his maximum achievable efforts.
In the third octave centered on 80 Hz, the transmissibility is quite uniform and much higher than 1. The hand
mechanical system translates like a solid body. At higher frequency the transmissibility maps become more and more
inhomogeneous and localized areas of higher level match the metacarpal bones (see for instance the third octave
centered on 500 Hz). On the contrary, the soft tissues are likely to better damp the vibration power since the
transmissibility is in these places much lower.
Fig. 2: Effect of frequency for a fixed coupling force : push@30% of push max - grip@15% of grip max
The effect of the coupling forces are investigated in the fixed third octave centered on 400 Hz. The transmissibility
maps are illustrated on Fig. 3 for 4 different pairs of push and grip force. The notation PxGy stands for x% of push
force and y% of grip force. The influence of the coupling force on the transmisssibility is clearly hihlighted here. Thus,
the higher the push and grip, the higher the transmissibility. Metacarpal bones still transmit most but the effect of push
and grip forces is visible even in the soft tissue areas. In fact, gripping or pushing changes the stiffness and the damping
properties of the soft tissues and then the way the vibration propagates.
Fig. 3: Effect of coupling forces for the fixed third octave centered on 400Hz
References
1. Dong, R.G., McDowell, T.W., Welcome, D.E. (2005). Biodynamic response at the palm of the human hand
subjected to a random vibration. Industrial Health 43(1): 241–255.
2. Rossi, G.L., Tomasini, E.P. (1995). Hand-arm vibration measurement by a laser scanning vibrometer.
Measurement 16(2): 113–124.
3. Concettoni, E., Griffin, M. (2009). The apparent mass and mechanical impedance of the hand and the transmission
of vibration to the fingers, hand, and arm. Journal of Sound and Vibration 325(3): 664–678.
4. Noël, C. (2011). Acceleration mapping and local biodynamic response of hand gripping a vibrating handle by
using laser scanning vibrometer. Buxton, Tuesday 20th to Wednesday 22nd September 2011. Buxton: Health &
Safety Laboratory. pp. 173–184.
60
HAND-ARM VIBRATION TRANSMISSIBILITY MEASUREMENT FOR ASSESSING
HEARING IMPAIRMENT
*Enrico Marchetti+,++, Renata Sisto+,++, Alessandro Lunghi++, Floriana Sacco++, Filippo Sanjust++,
Raoul Di Giovanni++, Teresa Botti++, Angelo Tirabasso++
+SapienzaUniversità di Roma, Department of Physiology and Pharmacology “V. Erspamer”.
++National Institute for Insurance against Accidents at Work, Department of medicine,
epidemiology, workplace and environmental hygiene.
Introduction
Assessment of physical interaction between noise and vibration exposure in human
subjects requires accurate measurement of the amplitude and frequency of vibration that travels
from the entering point (the hand for hand-arm HA) to the head, with some insight in order to
enhance correlation. In this study preliminary data are reported, limited to the forearm.
This work is directed to measure transmissibility of the forearm related to mechanical vibration
entering from the hand. Moreover, the skin effect and the coupling with the vibration source are
kept into account.
Methods
Measurement of vibration input and output for the forearm (hand-arm exposure) are
performed by a laser Doppler interferometer (Polytec, Germany, EU). Simultaneous (in phase)
measurement of grip force are carried out. In order to evaluate the transmissibility, input vibration
signals are standardized. Transmissibility is evaluated from data. A wide frequency range is
selected to keep into account also higher order harmonics, eventually arising from Tonic Vibration
Reflex (TVR). Thirty-four young volunteers have been selected: 15 females and 19 males. MV on
the handle was elicited by an electrodynamic shaker (RMS SW 1508, Germany, EU) driven by a
controller (Vibration Research VR 7500-2, Michigan, USA) at frequencies ranging from 6 to 500
Hz, with a transmissibility resolution of less than 1 Hz. The signal had an overall 26.9 ms-2 r.m.s.
acceleration. In order to take into account interpersonal differences the grip force exerted (GF) was
expressed in terms of Maximum Voluntary Contraction (MVC). Three levels of grip force (20%,
30% and 40%) relative to personal MVC have been selected, as typical of workers activity. The
posture was standardized following the UNI EN ISO 10819 (1998) for glove testing. All signals
were transmitted and recorded on digital analyzer OROS OR38 (Oros, France, EU). Data analysis
have been performed off-line with ad hoc applications developed with MatLab Release 2008a
(Mathworks, Massachusets, USA).
Results
Results show some well-known (and some less known) forearm resonances. Skin effect is
absent, as the laser beam direction is set orthogonal to the skin in a spot where the skin is tightly
wrapped around muscle and bone. Transmissibility preserve frequencies but tends to alters
amplitude. A good amount of vibratory energy reaches the shoulder.
61
Grip force level (MVC
percentage)
Transmissibility peak values in dB (and corresponding
frequency in Hz)
P1 P2 P3 P4
20 1.78 (8) 1.46 (24) -9.82 (61) -13.15 (87)
30 1.72 (8) 1.45 (29) -7.40 (63) -10.43 (87)
40 1.60 (8) 1.24 (34) -6.11 (64) -8.68 (88)
Conclusion
Comparison of actual data with those of other authors1,2 confirms that posture and force
are strong actors of the forearm response curve shaping, i.e. frequency transmissibility. The
method suggested in this work to match different muscular builds and genders is particularly
interesting because it is physiologically based on the functional stiffness that, supposedly, play a
paramount role in transmissibility. The observations referred in present paper suggest that the
resonances are the external evidence of some internal mechanical features of the hand-forearm
system. It is therefore a desirable perspective to develop a mechanical/digital model to elaborate
MV data on the hand in order to have theoretical MV on the elbow for every vibrating tool.
A good characterization of the vibration transmissibility to the head is essential for studying the
hearing effect due to simultaneous exposure to noise and vibration.
References
1. Sorensson A., Burtstrom L. (1997), Transmission of vibration energy to different parts of the
human hand-arm system, Int. Arch. Occup. Environ. Health, 70: 199-204.
2. Adewusi S.A., Rakheja S., Marcotte P., Boutin J. (2010), Vibration transmissibility
characteristics of the human hand–arm system under different postures, hand forces and
excitation levels. Journal of Sound and Vibration 329:2953–2971.
62
A NEW METHODOLOGY FOR MEASURING VIBRATION TRANSMISSIBILITY
ON A GRIPPED HANDLE FOR HAVS RESEARCH
*Almaky Almagirby, Matt J. Carré, Jem A. Rongong
Department of Mechanical Engineering, The University of Sheffield, Sheffield UK
Introduction
Many types of hand-held vibrating tool, such as chain saws, grinders, drills, and chipping
hammers are widely used in several industries. Extended exposure to vibration transmitted from
some of these tools may cause hand-arm vibration syndrome (HAVS) 1. International Standards
includes guidelines for the measurement and evaluation of human exposure to vibrations in the
hand 2. However, limited research exists that directly measures transmitted vibration through the
hand. Determination of transmitted vibration often depends on modelling of the system. The
reliability of these models depends on their ability to fully represent the actual hand-tool system
and the accuracy of the measurements that are used for calibration and validation 3. The dynamic
response of the human hand behaves differently among individuals. The new methodology
presented here allows us to measure and evaluate vibration transmissibility for a human finger in
contact with different materials, whilst measuring and controlling the grip force.
Methods
The experimental rig was set up to carry out vibration measurement in a single direction
(vertical excitation). A 40 mm diameter rigid cylindrical handle, made from aluminium, was setup
to be excited as a free-free system, excited by a V406 shaker (LDS) via amplifier (see Figure 1).
A reference accelerometer is located directly on the top of the driving point and the response
accelerometer is mounted on the end that is gripped (on the right hand side Figures 1 and 2). The
right end of the testing handle is instrumented to measure a grip force ranging from 10 N to 50 N,
based on the design used in ISO-10819 (1996) 4. This design uses a split cylinder with a strain
gauged beam element. The grip force measurement system was calibrated over a range 0 to 100
N.
Figure 3: Vibration and grip force test rig set up
Figure 4: Experiment set up showing
gripping of handle
63
National Instrument devices are used to drive the shaker and continuously display data on
the screen using LabVIEW software (version 2014). Frequency response functions (FRF) of the
system were collected from six positions along the handle length, using instrumented hammer
tests.
Results and Discussions
The FRF data obtained in each of six positions indicates that the dynamic system of the
handle has three modes at low frequencies (2, 11 and 17 Hz), and no other modes was present up
to a frequency of 550 Hz. (see Figure 3). A significant difference in FRF values were displayed at
two ends of the handle (position 1 and position 6) when compared with FRF values measured from
the middle position. This is thought to be due to rocking and twisting that occurs relative to the
shaker connection point. Overall, this study concluded that the new test rig is suitable for
measuring vibration transmissibility for HAV research. This is reasonable for testing vibration
transmissibility of gloves materials at frequencies ranging from 16 to 400 Hz, which are of
impotence to this research 4.
Figure 5: Frequency response function FRF for six position across the handle (left, 0 to 100 Hz;
right 100 to 1000 Hz)
References
1. Xu, X.S., Dong, R.G., Welcome, D. E., Warren, C., McDowell, T.W., An examination of the handheld
adapter approach for measuring hand-transmitted vibration exposure. Measurement, 2014. 47: p. 64-77.
2. ISO-5349-2, Mechanical vibration-Measurement and evaluation of human exposure to hand-transmitted
vibration. British standard, 2002.
3. Dong, R.G.Welcome, D.E., McDowell, T.W., and Wu, J.Z. Modeling of the biodynamic responses
distributed at the fingers and palm of the hand in three orthogonal directions. Journal of Sound and Vibration,
2013. 332(4): p. 1125-1140.
4. ISO-10819, Mechanical vibration and shock hand-arm vibration - Method for the measurement and
evaluation transmissibility of gloves at the palm fo the hand, in British standard. 1997.
64
NONLINEARITIES IN THE BIODYNAMIC RESPONSE OF THE HAND-ARM
SYSTEM TO SINGLE-AXIS VIBRATION
*Marco Tarabini, Lan Xie, Bortolino Saggin, Diego Scaccabarozzi
Politecnico di Milano, Department of Mechanical Engineering
Via Previati 1/C, 23900 Lecco, Italy
Introduction
The biodynamic response of the hand-arm system to single-axis vibration has been
commonly studied using the linear estimators of the frequency response function1-4. Nevertheless,
a nonlinearity versus the vibration amplitude was observed at low frequencies. Tarabini et al.2
reported that, in presence of unknown vibration direction, the vibration level affected the
impedance phase at low frequencies (octave band centered at 16 Hz), while the impedance
modulus variation was comparable to the tests variability. Burstrom evidenced a complex
dependence of the impedance magnitude from the vibration level5. The influence of different
velocity levels on the phase of the impedance was not statistically significant for any of the
directions.
In the existing literature studies, the biodynamic response have always been studied using
the linear estimators of the frequency response function6. In presence of nonlinear effects, the
linear estimators (power spectral density and cross-spectral density, PSD and CSD) of the FRF are
biased. The hypothesis of linearity is commonly verified by comparing the PSD and the CSD or
by analyzing the coherence function. Low coherence values are due to system nonlinearities, i.e.
to the lack of homogeneity or additivity or to the variation of modal parameters in time7,8.
Methods
This paper analyzes the response of the hand-arm system to vibration using the modelling
a nonlinear single input, single output system as a multiple input, single output system with
nonlinear inputs. If the hand-arm response to vibration is nonlinear, the force dependence from the
vibration is the sum of a linear function and of linear responses to nonlinear functions (quadratic,
cubic and modulus) of the input, as shown in Figure 6.
Figure 6 Proposed nonlinear model
The mechanical impedance of the hand-arm system has been measured by imposing a
vertical vibration to an instrumented handle. The experimental setup and the test protocol are
H1y(f)
H2y(f)
H3y(f)
squared
cubed
x(t)
x(t)
x² (t)
x³ (t)
y1(t)
y2(t)
y3(t)
+
N(t)
y(t)
HMy(f)abs|x|(t) yM(t)
...
65
described in ref. [2]. Eight subjects were asked to grip the handle with different shoulder, elbow
and wrist angles, exerting different push and grip forces, entailing different angles between the
vibration direction and the ISO 10068 reference axes. The response to vibration was modelled
using linear frequency response functions of the stimulus v, v2, v3 and |v|. The benefits deriving
from the adoption of a nonlinear model were assessed by comparing the conditioned response to
vibration using linear and nonlinear estimators and comparing the ordinary coherence with the
multiple coherence function. The importance of quadratic and cubic terms was evaluated by
comparing the conditioned response to the measured one, i.e. by analyzing N(t).
Results and Discussions
Experimental results evidenced that the introduction of the nonlinear terms increases the
coherence function especially in the low frequency region; two examples (Figure 7). Benefits
deriving from the adoption of a nonlinear model are more evident when the forearm is aligned
with the vibration direction and are expected to be relevant in case of response of the hand-arm to
shocks and transient vibration.
Figure 7 Comparison between the ordinary coherence (black line) and the conditioned coherence (red line). Dotted
lines indicate the SD of tests performed by different subjects.
References
1. Y. Aldien, P. Marcotte, S. Rakheja and P. E. Boileau, "Influence of hand-arm posture on biodynamic response
of the human hand-arm exposed to zh-axis vibration," International Journal of Industrial Ergonomics, vol. 36,
pp. 45-59, 2006.
2. M. Tarabini, B. Saggin, D. Scaccabarozzi and G. Moschioni, "Hand-arm mechanical impedance in presence of
unknown vibration direction," Int. J. Ind. Ergonomics, vol. 43, pp. 52-61, 2013.
3. Y. Aldien, P. Marcotte, S. Rakheja and P. Boileau, "Mechanical Impedance and Absorbed Power of Hand-Arm
under xh-Axis Vibration and Role of Hand Forces and Posture," Industrial Health, vol. 43, pp. 495-508, 2005.
4. P. Marcotte, Y. Aldien, P. E. Boileau, S. Rakheja and J. Boutin, "Effect of handle size and hand-handle contact
force on the biodynamic response of the hand-arm system under zh-axis vibration," Journal of Sound and
Vibration, vol. 283, pp. 1071-1091, 2005.
5. L. Burström, "The influence of biodynamic factors on the mechanical impedance of the hand and arm,"
International Archives of Occupational and Environmental Health, vol. 69, pp. 437-446, 1997.
6. J. S. Bendat and A. G. Piersol, Random Data: Analysis and Measurement Procedures. John Wiley & Sons, Inc.
New York, NY, USA, 1990.
7. M. Tarabini, S. Solbiati, G. Moschioni, B. Saggin and D. Scaccabarozzi, "Analysis of non-linear response of the
human body to vertical whole-body vibration," Ergonomics, pp. 1-13, 2014.
8. J. S. Bendat, Nonlinear System Analysis and Identification from Random Data. Wiley New York etc., 1990.
0.75
0.8
0.85
0.9
0.95
1
10 100
Co
her
ence
Frequency [Hz]
0.75
0.8
0.85
0.9
0.95
1
10 100
Co
her
ence
Frequency [Hz]
66
Session VI: Computer Modeling and Analysis
Chairs: Pierre Lemerle and Subhash Rakheja
Presenter Title and authors Page
Yue Hua A growth model of small artery for the vibration induced
Raynaud syndrome situation
Yue Hua, Pierre Lemerle, Jean-François Jean-François
Ganghoffer
67
John Z. Wu Three-dimensional finite element modeling of the effects
of gripping force on finger vibration transmissibility
John Z. Wu, Ren G. Dong, Daniel E. Welcome, Thomas
W. McDowell
69
Christophe Noël Validation of a 3d visco-hyper-elastic finite element
model for a pre-stressed vibrated distal forefinger
phalanx: mechanical and first thermal analysis
Christophe Noël
71
Shu Wang Biomechanical bent-arm model of the hand-arm system
coupled with an anti-vibration glove
Shu Wang, Subhash Rakheja, Paul-Émile Boileau
73
Sebastian Mangold The influence of the user on the power tool functionality -
a force sensing handle for a hammer drill
Sven Matthiesen, Sebastian Mangold, Tim Bruchmueller,
Daniel Stelzer, Bernhard Truenkle
75
Sven Matthiesen
A method to develop hand-arm models for single impulse
stimulation
Sven Matthiesen, Sebastian Mangold, Tobias Schäfer,
Sebastian Schmidt
77
René Germann A method to design a hand arm model with translational
and rotational degree of freedom for high accelerated
applications
Sven Matthiesen , René Germann, Sebastian Mangold
79
67
A GROWTH MODEL OF SMALL ARTERY FOR THE VIBRATION-INDUCED
RAYNAUD SYNDROME SITUATION
*Yue HUA+, Pierre LEMERLE+, Jean-François GANGHOFFER++ +Laboratoire de Modélisation des Systèmes Mécaniques de Prévention, Institut national de recherche et de
sécurité, 1 rue du Morvan, Vandœuvre-lès-Nancy, 54519 Cedex, France ++Laboratoire d’Energétique et de Mécanique Théorique et Appliquée , UMR 7563, Université de Lorraine, 2
avenue de la forêt de Haye, 54502 Vandœuvre-lès-Nancy, France
Introduction
Hand-arm Vibration Syndrome (HAVS) originates from the use of hand-held power tools. With respect to
higher frequency vibrating tools (>50 Hz), HAVS is generally known as peripheral circulatory disorders in the hand.
It is basically caused by an abnormally strong vasoconstriction of blood vessels. Past studies suggest that a reduction
of lumen of the blood vessels in Vibration White Finger subjects, because of either hypertrophy or thickening of the
vessel wall, would be responsible of the disease1,2. But how the load of the hand-held tools affects the structure of
blood vessels, in a direct (vascular impairment) or indirect ways (as a result of neurological damage), is still
controversial3. In this paper, a mechano-biological relationship type is assumed and we aim to construct a growth
model of small arteries capable of predicting the structure changes of the arterial wall in function of the vibration
exposure.
Method
We use the Continuum Mechanics approach for the modeling of small artery growth. The governing
equations are based on the kinematics of finite growth combined with the framework of open system thermodynamics.
We introduce an intermediate configuration without any elastic deformation for finite growth and the deformation
gradient was multiplicatively decomposed into a reversible elastic part (elastic deformation gradient) and an
irreversible growth part (growth deformation gradient), which was first used to describe the growth of biological
tissues by Rodriguez et al. (1994)4. To compute the growth processes, the growth gradient of deformation is considered
as an internal scalar variable and computed locally at each integration point level and each instant, by the equation of
volume growth law proposed by Kuhl et al. (2007)5.
The artery is modeled as a long tube with a nonlinear hyper elastic material.
The theory of plane deformation is used to solve the problem in 2D. In reality, using
hand-held power tools induces high pressure levels in the finger tissues. We know
through the optical research of Masato Ohmi (2013)6 that the artery deforms and
becomes elliptic when the finger is pressed against a glass plate (fig. 1), which is
comparable with tool gripping conditions. Hence, at the artery scale, these conditions
are modeled with a pressure applied symmetrically on the outer surface. The loading
is divided in 4 stages: quasi-static compression– small vibration – quasi-static release–
unloading (fig. 2).
The elastic material parameters of the tube wall are chosen as λ = 1.43 MPa and µ = 0.357 MPa (Lamé
coefficients), which correspond to a Poisson’s 0.4 and a Young’s modulus of 1MPa7. The dimensions of the small
artery were estimated from the optical research of Masato Ohmi (2013)6. The outer and inner radii are chosen as 0.5
mm and 0.375 mm respectively.
Fig.1: OCT image of a
small artery when the
finger is pressed
against a glass plate6
P
P
Fig.2: Load application
and process description
68
Results and Discussions
The results presented in the following are based on simulations carried out with FreeFEM ++, which is a free
open source partial differential equations solver. Thanks to symmetries along the X and Y axes, only ¼ of the structure
needs to be modeled with suitable boundary conditions.
Fig. 3 shows the mesh and the deformed shape of ¼ artery; it illustrates the spatio-temporal evolution of
volume growth gradient of deformation (color scale). The load was applied by incremental steps in a large strain
approach. At instant 𝑡 = 𝑡0+, the artery deforms due to the mechanical loading. The initial growth gradients of
deformation equal unity. Then the growth starts in the outer part of the free lobe, where the stress is the largest. At
this location and at 𝑡 = 𝑡0+, the thickness of the artery increases from 0.125mm to 0.146mm. At 𝑡 = 𝑡1
+, when the load
is released, the artery cannot deform back to its initial shape and due to the growth localized in the outer part of the
lobe, the inner part is subjected to high stress during the unloading stage. As a result, the inner area begins to growth.
Finally, we obtain a thickness of 0.147mm, i.e. about 17.6% more than the initial thickness. The asymmetric loading
leads to an asymmetric irreversible growth and finally to an asymmetric shape.
Although the proposed model qualitatively reports the thickening of a small artery wall under the asymmetric
compressive oscillatory stress, many items still need some improvement. First, more realistic constitutive models for
the artery have to be adopted, which in reality consists of three nearly incompressible layers, including a residual stress
in the artery wall and a spatio-temporal blood pressure law. In Kuhl’s model, the relaxation time of the growth process
is governed by two parameters. As the original approach addressed the prediction of the final state at biological
equilibrium (for instance driven by the long-term high blood pressure effects), no validated values or estimates were
required. In our problem, this is no longer correct as clearly two timescales are playing a role, the growth time constant
and the characteristic time of the excitation, namely the vibration period. However, in the case study illustrated above,
the growth is mainly due to the static load, as the model is driven by the stress-state (and 𝑃 ≈ 𝑃0 over time). In the
next step of our research, we aim to extract information regarding these quantities from published experimental
studies, by means of tuning methods. It seems the most exploitable observations have been obtained from tests carried
out on animals.
Reference 1 Gemne, G. (1994). Pathophysiology of white fingers in workers using hand-held vibrating tools. Nagoya J Med Sci. 57
(Suppl.), pp. 87-97.
2 Hashiguchi T., Yanagi H., Kinugawa Y., Sakakibara H., Yamada S. (1994). Pathological changes of finger and toe in patients
with vibration syndrome. Nagoya J Med Sci., vol. 57(Suppl.), pp.129-136.
3 Stoyeva Z., Lyapina M., Tzvetkov D. Vodenicharov E. (2003). Current pathophysiological views on vibration-induced
Raynaud's phenomenon. Cardiovascular Research, 57 (3), 615-624.
4 Rodriguez E.K., Hoger A., McCulloch A.D. (1994). Stress-dependent finite growth in soft elastic tissues. J Biomech, vol.27,
pp.455-467.
5 Kuhl E, Maas R, Himpel G, Menzel A. (2007). Computational modeling of arterial wall growth. Attempts towards patient-
specific simulations based on computer tomography. Biomech Model Mechanobiol, vol.6, pp.321-331.
6 Ohmi M., Kuwabara M., Haruna M. (2013). Dynamic imaging of a small artery underneath skin surface of a human finger by
optical coherence tomography. J. Biomedical Science and Engineering, vol.6, pp.249-252.
7 Langewouters G.J., Zwart A., Busse R., Wesseling K.H. (1986). Pressure-Diameter Relationships of segments of human finger
arteries. Clinical Physics and Physiology Measurement, vol.7, pp.43-55.
Acknowledgments: The authors would like to express their appreciation for all advice and comments received from Christophe Noël (INRS) and
Gérard Maurice (Université de Lorraine).
Fig.3 Deformed shape of a ¼ artery and evolution of growth at 𝑡 = 𝑡0+ ; 𝑡 = 𝑡1
−; 𝑡 = 𝑡1
+; 𝑡 = 𝑡2 (from left to right)
t=t1 t=t1
69
THREE-DIMENSIONAL FINITE ELEMENT MODELING OF THE EFFECTS OF
GRIPPING FORCE ON FINGER VIBRATION TRANSMISSIBILITY
*John Z. Wu, Ren G. Dong, Daniel E. Welcome, Thomas W. McDowell
Engineering and Control Technology Branch, Health Effects Laboratory Division,
National Institute for Occupational Safety & Health, Morgantown, WV, USA
Introduction
Mechanical stress and strain in the soft tissues -- the essential factors that modulate the
growth, remodeling, morphogenesis of the biological system -- have been proposed to be
associated with the initiation and development of the hand-arm vibration syndrome1. However, the
vibration induced dynamic stress and strain in living tissues cannot be determined by using either
experimental methods or traditional lumped mass models2. In the current study, we proposed a
hybrid modeling method to analyze the biodynamic responses of the finger when gripping a
vibrating cylindrical tool handle.
Methods
The 3D finite element (FE) gripping model features a finger and a cylindrical handle (Fig.
1A-B). The model includes three finger segments (distal, middle, and proximal phalanges), three
joints [the distal interphalangeal (DIP), proximal interphalangeal (PIP), and metacarpophalangeal
(MCP) joint], and contains the major anatomical substructures of the finger (i.e., soft tissues, nail,
and bone)3. The cylinder (d = 40 mm) was considered of aluminum and covered with thermoplastic
materials (thickness 1.5 mm). The coupling of the local and global dynamic responses is
considered by introducing lumped parameters2. The effective mass of the hand-arm is represented
by the mass element M at the MCP joint. The coupling between hand, forearm, and ground is
represented using three sets of spring/damping units (ki and ci, i=1,2,3), which are linked to the
ground in x, y, and z direction. The coupling effect between the palm and cylinder is represented
by another spring/damping unit (k4 and c4), which links the MCP joint center to the cylinder center.
The bone and nail are considered as linearly elastic, whereas the soft tissues are considered as
hyperelastic and viscoelastic4. The nonlinearly elastic behaviors are characterized by using a two-
term Mooney-Rivlin model, whereas the viscoelastic properties are formulated using a three-term
Prony-series model in the frequency-domain. In addition, the Rayleigh formula is introduced to
include the tissues’ frequency-dependent viscous damping5. The model parameters were
determined by fitting the model to experimental measurements6. The simulations were
accomplished in two stages. First, the finger was deformed under static gripping, which was
Figure 1. Gripping model.
A: Finite element modeling
of a finger. B: Hybrid model
of gripping vibration. The
model was constructed
using a commercially
available FE software
ABAQUS.
70
realized by applying moments at the DIP, PIP, and MCP joints; the joint moments represent the
musculoskeletal forces during gripping. Secondly, vibratory loading was applied at the cylinder
center, which represents tool vibration, such that the finger vibrates at the deformed states.
Results and Discussions
Fig. 2A shows the simulated static contact pressure on the soft tissues of the finger when
the hand grip force reached approximately 30N and before the vibratory loading was applied on
the cylinder. According to the model predictions, the maximal tissue stress is manifested in the
middle finger segment, which is different from those observed in the power gripping tests3. The
simulated frequency-dependent vibration transmissibility of the finger segments is illustrated in
Fig. 2B. The transmissibility shown is the total transmissibility that included the vibrations in all
three directions. The results indicate that resonant frequencies at the distal, middle, and proximal
segments are 115 Hz, 105 Hz, and 88 Hz, respectively. The corresponding transmissibility
magnitude increases slightly from the distal to the middle and to the proximal segments. The
resonant frequency increases with increasing grip force (results not shown). The general trends of
the finger vibration characteristics predicted using the proposed model agree well with those
measured experimentally6. Using the proposed model, the coupling effects among the muscle
forces and the vibrations of the soft tissues of the finger and the global hand-arm system can be
naturally simulated.
References
1. Dong RG, Welcome DE, McDowell TW, Xu XS, Krajnak K, and Wu JZ, 2012. A proposed theory on biodynamic
frequency weighting for hand-transmitted vibration exposure, Industrial Health 50(5): 412-424.
2. Dong RG, Dong JH, Wu JZ, Rakheja S. 2007. Modeling of biodynamic responses distributed at the fingers and
the palm of the human hand-arm system. J Biomech. 40:2335-40.
3. Wu JZ, Dong RG, Warren CM, Welcome DE, McDowell TW. 2014. Analysis of the effects of surface stiffness
on the contact interaction between a finger and a cylindrical handle using a three-dimensional hybrid model. Med
Eng Phys. 36:831-41.
4. Wu JZ, Dong RG, Smutz WP, Schopper AW. 2003. Nonlinear and viscoelastic characteristics of skin under
compression: experiment and analysis. Biomed Mater Eng. 13:373-85.
5. Wu JZ, Dong RG, Welcome DE. 2006. Analysis of the point mechanical impedance of fingerpad in vibration.
Med Eng Phys. 28:816-26.
6. Welcome DE, Dong RG, Xu XS, Warren CM, McDowell TW. 2014. The effects of vibration-reducing gloves on
finger vibration. Int J Indus Ergon. 44:45-59.
Figure 2: Predicted static contact pressure and transmissibility of the finger segments. A: Distribution of the
contact pressure on the soft tissues. B: Predicted transmissibility of the finger segments. DIS, MID, and PRO
represent the distal, middle, and proximal segment of the finger.
71
VALIDATION OF A 3D VISCO-HYPER-ELASTIC FINITE ELEMENT MODEL FOR A PRE-STRESSED
VIBRATED DISTAL FOREFINGER PHALANX: MECHANICAL AND FIRST THERMAL ANALYSIS
*Christophe Noël
Laboratoire de Modélisation des Systèmes Mécaniques de Prévention
Institut national de recherche et de sécurité (INRS)
1 rue du Morvan - CS 60027 - F-54519 VANDOEUVRE cedex, France
Introduction
Extensive exposure of the hand-arm system to regular vibration can lead to various disorders and injuries due
in part to changes of mechanical quantities like dynamic stress or strain arising from the propagation of such vibration.1
Nowadays the direct measurement of this biodynamic response inside soft tissues is still a great issue, thereby finite
element models have been developed in order to assess the dynamic mechanical variables by numerical computation.2
Despite previous modelling approaches succeeded in reproducing qualitative observations, they have not been fully
correlated with experimental data. Our work aims at establishing and verifying a reliable high fidelity 3D finite
element model allowing the simulation of mechanical and thermal effects generated by vibration transmitted to a
statically preloaded distal forefinger phalanx. In particular, we wish to identify both the most suitable hyper-elastic
and damping behaviour laws and their related parameters which best fit measured static and dynamic finger’s stiffness.
A special attention was paid to the choice of a physiological and phenomenological damping law relevant for soft
tissues since damping is directly linked to the dissipated mechanical power3 which could be partly responsible for the
onset of hand-arm vibration syndromes.1-2
Methods
Both static and dynamic finger’s rigidities were measured
for 20 subjects aged from 19 to 39 with normal cutaneous sensory
threshold (monofilament size 3.61 in the Semmes-Weinstein test).
Each subject was advised to place its forefinger distal phalanx nail
on a specific support as depicted on Fig. 1. The static stiffness was
then measured thanks to a force sensor and a laser telemeter by
loading the finger with the contact indenter. The dynamic stiffness
modulus and the phase were next valued in the frequency band
[25Hz-500Hz] with an impedance head and a force sensor for compression levels corresponding to static stiffness of
8 N.mm-1 and 10 N.mm-1. The experimental setup was checked by measuring the pure real stiffness of a spring and
by comparison with data acquired for polyurethane foam and soft rubber on a commercial dynamic mechanical
analysis (DMA) tester.
Regarding modelling, as shown in Fig. 2 a 3D geometry and associated tetrahedral meshes (5072 nodes,
19676 meshes) were built for an index finger with the following anatomical elements: nail, bones for the distal-middle-
proximal (half) phalanges, interphalangeal articular cartilage and surrounding homogeneous skin and subcutaneous
tissues. Boundary conditions and dimensions (average lengths of subjects for
outer sizes and inferred from morphological rules4 for inner dimensions) are
summed up on Fig. 2. Bones, nail and cartilage are modelled as standard
linear solids (Zener model) with parameters coming from bibliography.5 Soft
tissue visco-hyper-elastic laws and parameters were identified by splitting
the whole issue in two steps. Firstly, we have dealt solely with the non-
viscous elastic behaviour law. The Ogden-Hill law was tested the most
suitable compressible constitutive law. The inherent parameters were then
identified by using a non-linear data-fitting algorithm between measured and
computed static stiffness. Our work main contribution is based on the way to take into account damping properties.
Starting from the well-known quasi-linear viscoelasticity3-5 theory, the second Piola-Kirchhoff stress tensor can be re-
written in the spectral domain for the case of an infinitesimal harmonic strain around a large static deformation. In this
way, this stress tensor is composed as the product of a tensor related to the static state and a complex function of
frequency describing the damping behaviour. The resulting mathematical form is therefore quite similar to that used
in conventional linear viscoelasticity and thereby it is a mean to use the infinite variety of linear damping models.
Many of such models have been implemented (rheological or fractional derivative models) but those based on the
Fig. 1: Experimental apparatus
Fig. 2: Modelling settings
72
decomposition of relaxation functions as continuous sum of relaxation spectra3 have led to the best results possibly
because many of them are based on physiological background. Damping parameters are determined by minimizing
the gap (magnitude and phase) between the numerical and the experimental dynamic stiffness.
Results and Discussions
For the hyper-elastic static step, we chose an Ogden-Hill law of order one namely with three physical
parameters which were identified as explained previously. As shown on Fig. 3(a), we selected as comparison metric
the static stiffness derivative in function of the static stiffness. The gap between the simulations and the measurements
is really tiny around a few per cent and remains always inside the bounds of the 95% inter-subjects confidence interval.
As regards damping properties, we used as relaxation spectrum the box spectrum function most adapted for biological
soft tissues containing collagen fibres such as skin.5 Measured dynamic stiffness around preload corresponding to a
static stiffness of 10 N.mm-1 was selected for the parameters identification process. As drawn on Fig. 3(b), simulations
are in good agreement with experimental data. Mainly, numerical results well highlight the stiffness gradual rise up
to 100 Hz with steeper slope at higher frequencies. Moreover, the stiffness was computed at a pre-stressed of 8 N.mm-
1 and remains very close to measured data. This confirms that our model is sufficiently accurate and predictive.
Fig. 3: Comparison of experimental and computational static (a) and dynamic (b) stiffness
As a first application displayed on Fig. 4(a), we computed the average of the mechanical power density dissipated
during one cycle when the forefinger is vibrated by a single harmonic excitation at 100 Hz with acceleration amplitude
of 40 m.s-2 (usual grinder). The maximum power density is around 1mW.mm-3, localized in the vibrated area width
and spreads up to the bone. This mechanical dissipated power density can be introduced as an external heat source in
Pennes bioheat5 equation which models the heat transfer in living tissues by taking into account the heat generated
both by the blood flow and the metabolism. Therefore as depicted in Fig. 4(b), the temperature field induced by
previous vibration can be computed. For an exposure time of 10 min and surrounding air at 23 °C, it reaches a
maximum of 38.5 °C in the same area as the higher mechanical power. Even though this temperature is not high
enough to cause direct damages (collagen denaturation), it has been shown that a moderate increase could nevertheless
lead to changes in the rate of biochemical reactions including enzymatic or cellular activities.5
Fig. 4: Mechanical power density (a) - logarithmic scale [mW.mm-3] and induced temperature [°C] field (b)
References
1. Burns, T., Breathnach, S., Cox, N., Griffiths, C. (2010). Rook’s textbook of dermatology. Chichester, Wiley.
2. Wu, J.Z., Dong, R.G., Welcome, D.E., Xu, X.S. (2010). A method for analyzing vibration power absorption
density in human fingertip. Journal of Sound and Vibration 329: 5600–5614.
3. Lakes, R. (2009). Viscoelastic materials. New York, Cambridge University Press.
4. Schmidt, H.-M., Lanz, U. (2004). Surgical anatomy of the hand. Stuttgart, Thieme-Verlag.
5. Xu, F., Lu, T. (2011). Introduction to skin biothermomechanics and thermal pain. Berlin, Springer-Verlag.
2 4 6 8 100
5
10
15
20
25
30
Static stiffness [N.mm-1]
Sta
tic s
tiffness d
erivative [N
.mm
-2]
Modelling
Experimental
95% confidence interval
25 31.540 50 63 80 100 125 160 200 250 315 400 500 0
10
20
30
40
50
60
70
Frequency [Hz]
Dynam
ic s
tifn
ess m
agnitude [N
.mm
-1]
Modelling@pre-stressed=10N.mm-1
Experimental@pre-stressed=10N.mm-1
Modelling@pre-stressed=8N.mm-1
Experimental@pre-stressed=8N.mm-1
(a) (b)
(a) (b)
73
BIOMECHANICAL BENT-ARM MODEL OF THE HAND-ARM SYSTEM COUPLED
WITH AN ANTI-VIBRATION GLOVE
*Shu Wang+, Subhash Rakheja+, Paul-Emile Boileau++
+Concave Research Centre, Concordia University, Montreal, QC, Canada ++IRSST, Montreal, QC, Canada
Introduction
The control of hand-transmitted vibration (HTV) can be realized through isolating hands
from vibrating tool handles. Gloves with different vibration isolation materials have been widely
proposed to obtain some degree of vibration suppression. Air bladder glove is one of the anti-
vibration gloves for which the air enclosed in tiny bladders provides vibration isolation effect
between hands and the tool handle in specific frequency ranges. In this paper, an air bladder anti-
vibration glove model proposed in [1] is integrated to a biomechanical bent-arm model of hand-
arm system (HAS) proposed in [2] to investigate its vibration isolation effectiveness.
Methods
Figure 1(a) shows the coupled gloved hand-arm-tool system model, for analysis of the
vibration responses along the 𝑧ℎ- axis. The model reported for the bent-arm posture was formulated
and analyzed to assess its suitability for application to a percussion tool model, shown in Fig. 1(b).
The responses of the HAS model coupled with the tool were assessed in terms of its ability to
predict measured driving-point mechanical impedance (DPMI) and vibration transmissibility
responses near the wrist, elbow and the shoulder joints, and dynamic responses of the tool.
Furthermore, the suitability of the HAS model was assessed by determining its static deflections
under two different levels of static push force (50 N and 75 N).
(a) (b)
Figure 1: (a) Gloved hand-arm-tool model in bent-arm posture; and (b) percussion tool model
The parameters of the HAS model associated with different push forces (50 N and 75 N)
and a constant grip force of 30 N were identified by minimizing a weighted sum of errors between
the model and measured DPMI and vibration transmissibility responses [2]. The baseline
parameters for the air glove model were taken as those reported in [1]. The measured DPMI
responses, corresponding to 50 N and 75 N push, respectively, and 30 N grip force were attained
74
through laboratory tests with six male subjects. The measured data were extracted using broad
band zh-axis vibration in the 2.5 to 500 Hz frequency range (frequency-weighted rms acceleration
= 5.25 ms-2). The zh-axis vibration transmissibility responses distributed in the hand- arm system
were obtained through solutions of the equations of motion for the bent-arm model. For instance
the vibration transmissibility response at the wrist, Tw(jω) at excitation frequency ɷ was obtained
from the motion response magnitudes of the palm mass Zp and handle Zc, such that:
(1)
Results and Discussions
Figure 2 shows the comparisons of the vibration transmissibility responses at the wrist of
the bent-arm model with and without the anti-vibration glove with the mean measured data of the
bare hand corresponding to two different levels of the push force (50 N and 75 N) and constant
grip force of 30 N. Although some differences are noted, particularly for higher push force, the
bent-arm model yields generally good agreements with the mean measured data for bare hand. The
comparisons of the vibration transmissibility of the bare-hand and the gloved hand models suggest
that the addition of anti-vibration glove tends to amplify vibration slightly around the primary peak
near 12 Hz. The glove, however, tends to attenuate palm vibration in the 32 to 100 Hz frequency
range. Similar trends are also evident in the model responses under 30 N grip and 75 N push forces,
for which peak amplification is seen to occur around 14 Hz. The results suggest that the anti-
vibration glove considered may not yield effective vibration protection for the operators exposed
to the low-frequency power tool, but could provide attenuation of medium frequency vibration
transmitted to the hand, particularly at higher push force. The palm vibration isolation could be
enhanced by reducing the glove stiffness, which would likely lead to thicker isolation material and
loss of dexterity. The gloves also showed considerably higher vibration transmission to the fingers.
Figure 2: Comparisons of 𝑧ℎ-axis vibration transmissibility responses of the bare and gloved
hand-arm models at the wrist with the mean measured responses of the bare hand: a) 50 N push,
30 N grip forces; b) 75 N push, 30 N grip forces.
References
1. Dong, R.G., McDowell, T.W., Welcome, D.E., Warren, C., Wu, J.Z., Rakheja, S., 2009. Analysis of anti-vibration
gloves mechanism and evaluation methods. J. sound and Vibration, 321, 435-453.
2. Adewusi S., 2009. Distributed biodynamic characteristics of the human hand-arm system coupled with vibrating
handles and power tools. Ph.D. thesis, Montreal, Concordia University.
( )( )
( )
p
w
c
Z jT j
Z j
(a) (b)
75
THE INFLUENCE OF THE USER ON THE POWER TOOL FUNCTIONALITY
- A FORCE SENSING HANDLE FOR A HAMMER DRILL -
Sven Matthiesen, *Sebastian Mangold, Tim Bruchmueller, Daniel Stelzer, Bernhard Truenkle
IPEK – Institute of Product Engineering, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
Introduction
This paper presents an approach to investigate the influence of the user’s posture, grip force and push force
on the functionality – feed rate per time – of a hammer drill.
The continuous comparison between required and achieved product functions - known as validation - is one
of the key activities within the product development process. In the case of power tools, these product functions depend
on the one hand on the interactions between the user and the power tool, and on the other hand on the interactions
between the power tool and its application1. Therefore, in validation activities, it is necessary to understand the power
tool as a super system consisting of these three aggregated subsystems. In power tool development most validation
activities take place in test centers. Testing conditions, defined by the product developers, are usually very strict in
order to overcome the uncertainties caused by the complex interactions of the power tool with applications and users.
Anyway, the quality of power tool validation is still limited by the heterogeneous interactions between user and power
tool. This heterogeneity may lead to variant drilling effectiveness (feed rate per time) of a newly designed hammer
mechanism in a hammer drill prototype. This unclear influence on the technical system is problematic for the designers
because they cannot validate the effectiveness of their product improvement. To overcome this uncertainty,
mechanical analogous systems on test rigs may replace the individual human user. Therefore, the dynamic reaction of
user’s hand-arm movements has to be equivalent to that of the mechanical analogous system2. Unfortunately hand-
arm-models are usually designed to consider the same vibration on a power tool handle as a hand-arm-system. The
functionality of the super system consisting of the power tool, the user and the application hasn’t been included in the
modeling of hand-arm-models, yet. Additionally, it is difficult to apply and adjust the required push force on the power
tool under sufficient static deflection of the model’s masses.3
It is well known that a user’s posture, grip force and push force have distinct influences and have to be
included in the analysis of the dynamic behavior of the hand-arm-system. To develop a test rig for feed rate
measurement it is necessary to understand which of the mentioned parameters have to be considered in the
development of a sufficient hand-arm-model. This paper presents a force sensing handle for hammer drills and
discusses the various parameters influencing the feed rate. Based on this handle it will be possible to evaluate hand-
arm-models on their ability to induce user-like forces on a power tool handle of an operating hammer drill.
Methods
Figure 1 (left) displays the modified hammer drill with its force sensing handle. Figure 1 (right) displays the
schematic setup of the modified hammer drill with all its sensors, numbered from 1 to 6.
Fig.1: Modified hammer drill and schematic force sensing handle
The force sensing handle is connected by piezoelectric force transducers (1 and 2) with the housing of the hammer
drill. The single axis force transducer in the upper connection (1) allows the measurement of the dynamic force in the
direction of hammering action. The bottom force transducer (2) measures in two directions – the hammering direction
and the tangential direction relative to the drilling axis. Both sensors are preloaded and therefore capable of detecting
the dynamic pulling and compression forces simultaneously on the top and bottom of the user’s hand. Next to the
force transducers, towards the hand of the user, two tri-axial accelerometers (4 and 5) allow the measurement of the
76
acceleration forces in the axial direction of the hammer action and tangential to the drilling axis. The hand enclosed
area of the force sensing handle contains a customized grip force measurement device (3). The handle is split in half
and connected through a three point bending beam applied with four strain gauges. Grip forces in the direction of the
hammer action can be measured but orthogonal ratios cannot be detected. To evaluate the drilling process a laser
distance sensor (6) measures the feed rate of the hammer drill. The laser beam points onto the tip of the drill to reduce
inaccuracies caused by angular changes during the drilling process.
The functionality of the power tool is quantified through the feed rate (distance per second) while hammer
drilling concrete. To investigate the user’s influence on the power tool functionality an explorative study with one
male user was conducted. The user was asked to drill holes with one hand in two postures (displayed in figure 2) by
holding push force and grip force as constant as possible. In order to do so, the push and grip force was displayed to
the user with a sample rate of 2 Hz. The posture was observed and controlled by a visual comparison between shown
postures in figure 2 and a web cam live stream. For each posture configuration, using two grip forces and two push
forces, the feed rate was measured in ten trials. The range of a reasonable push force variation was identified through
a screening test measuring the push force of several male and female users.
Results
In Figure 2 the measured feed rate is displayed depending on the push force, grip force and posture for the
best five trials (push force and grip force within 10% variation). The bar chart shows the average feed rate. The
variance of the five best trials is shown by the black line within this plot.
Fig. 2: Measured feed rate while hammer drilling depending on push force, grip force and posture
The push force has a large influence on the hammer drill’s feed rate and therefore on the hammer drill’s
functionality. In contrast, the different postures and grip forces have no substantial influence on the feed rate. The
measured push force in the screening test was in the range between 50 N and 300 N. As a result of this investigation
it can be stated that a test rig hand-arm-model for feed rate measurement of hammer drills has to produce the same
push forces as the user (up to 300N) under sufficient static deflection of the model’s masses. It does not necessarily
have to have adjustable parameters for grip force and postures. Further investigations have to figure out, if this finding
is also valid for the validation of other product functions like power consumption or power tools’ life expectancy.
References
1. Matthiesen, S., Schäfer, T., Mangold, S. (2012): Modelling and Simulation of the Hand-Arm-System during
Impact Influences. ASME International Mechanical Engineering Congress and Exposition, Volume 2:
Biomedical and Biotechnology: 909-918.
2. Marcotte, P., Boutin, J., Jasinski, J. (2010): Development of a hand–arm mechanical analogue for evaluating
chipping hammer vibration emission values. J. of Sound and Vibration 329, Issue 10: 55-82
3. Dong, R. G., Welcome, D. E., Wu, J. Z., McDowell, T. W. (2008): Development of hand-arm system models for
vibrating tool analysis and test rig construction. Noise Control Engineering Journal 56(1): 35–44.
77
A METHOD TO DEVELOP HAND-ARM MODELS FOR SINGLE IMPULSE STIMULATION
*Sven Matthiesen, Sebastian Mangold, Tobias Schäfer, Sebastian Schmidt
IPEK – Institute of Product Engineering, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
Introduction
The aim of this paper is to describe a method of calibrating a durable and test-rig-suitable hand-arm model
that is valid for simulating the responses of the hand-arm system to high impulsive accelerations.
Developing or optimizing power tools, is nearly impossible without considering the interdependencies
between human, tool and application. Therefore, the super system (user, power tool and application) must be
considered as a holistic system. In validation tasks within the product development process, the impossibility of
dividing this system leads to many uncertainties. Through the intensive interaction between the user and the power
tool, there is a significant impact on the life expectancy and functionality of the power tool. Therefore, the researchers
aim is to develop mechanical analogous systems to describe the mechanical influence of the hand-arm system on
power tools. By implementing those models into test rigs, most researchers pursue the approach of low-complexity,
linear, and lumped-parameter models1. Biomechanically motivated models that investigate internal forces or vibration
transmission within the hand-arm-system and have a higher model complexity do not have the necessary durability
for test rig application1. Despite an abundance of investigations that model the human response on vibrating power
tools, only a few investigations focus on high deflecting single impulses. In the case of such impulses, according to
Griffin2, the user performs a shock motion, because it is a deterministic, non-periodic movement. A method to analyze
such shock motion will be presented in this paper. Additionally, the method will be demonstrated by the development
of an example model that describes those interactions between a power tool and the user.
Methods
In principle, there are three methods that investigate the human response to motion stimulations (mechanical
impedance) caused by power tools. Figure 1 illustrates these methods: (1) Use of a stimulation system (e.g. shaker
systems) with a measurement handle to not only stimulate the hand-arm-system but also measure the force and
deflection at the handle bar. (2) Manipulation of a power tool’s handle to measure force and deflection in real
applications. (3) Creation of a model of the overall system (tool, hand-arm-system and application) to simulate the
force and deflection. The aim of this study is to describe a method to parameterize a durable and test-rig-suitable hand-
arm model that is valid for high deflections and very high accelerations. The method of using a shaker as a substitute
system (1) to investigate the driving point impedance of the hand-arm-system, is widely described for vibrations (e.g.
Dong3). Unfortunately nowadays there are no stimulation systems
available with high deflections and very high accelerations to
stimulate realistic impulses. By manipulating the power tool’s
handle (2) there is a risk of unknown influences caused by the
implementation of the sensors (mass, stiffness). Such manipulated
handles are described in a few studies, but not in case of high
impulsive power tools. This paper presents an example for method
(3) – An investigation of the human response on motion stimulations
by using a theoretical overall model for power tool and user
interaction. With this approach neither a substitute stimulation
system nor an integrated force measurement system in the power
tool handle is needed. The method is based on the idea that any kind of user interaction at the power tool handle will
directly lead to an influence of the power tool’s behavior. Figure 2 illustrates this innovative method. At first,, a model
without user influence is used to predict the power tool’s behavior under well-known conditions. Second, the
interaction between the subsystems user and power tool is visually analyzed with a high-speed camera system to obtain
hints of how the model needs to be structured (e.g. movements in only one direction). Third, the model of the power
tool’s behavior without user influence (model-based to eliminate the well-known influence) has to be combined with
the user’s structure model of the second step. In this third step, the parameters of the user’s structure model have to
be iterated, until the behavior of the power tool in the overall system’s simulation matches the observed power tool’s
behavior in real application.
To demonstrate this method a highly accelerating power tool, a direct fastening device (i.e., bolt setting
device and a powder actuated nail gun) is used as a sample in this study. These power tools are usually used in
Fig. 1: methods to develop a hand-arm model
78
construction and manufacturing to fix sheet metal parts onto steel or concrete. Caused by a pyrotechnical combustion
of a powder cartridge, the tool accelerates up to 3600 m/s² in one single shock. Within the first step, the power tool is
simplified to a spring-mass-damper system. This model describes the masses’ movements while setting nails without
the user’s influence. To identify the internal tool characteristic, the power tool safety features are manipulated so that
it is possible to actuate it without any user interaction. By comparing the measured and simulated masses’ movement
(velocity), the spring value, damping value and the motion force (Fcartridge - responsible for power tools movement) are
calculated in MATLAB Simulink®. Without user interaction, the force (Fpressing down) is zero and the masses (m1 & m2)
do not exist. The power tool loses contact to the ground right after combustion. Therefore, no forces are induced into
the power tool from application. Thus, an application or nailing model is not needed. Within the second step, the
interactions between a user and the power tool has been visually analyzed with a high-speed camera. It has been
observed that the power tool’s movement is mostly in one direction. Additionally, it has been observed that at first,
the user’s ball of the thumb is compressed completely, and afterwards, the hand starts to accelerate. As a result, a one
dimensional linear spring-damping system with graded stiffness and damping rate, as shown in figure 2, is needed to
simulate the interactions between a user and the power tool. After building a power tool model (step 1) and a structure
model of the user (step 2), the whole system can be built up in MATLAB Simulink® through the combination of the
two sub-models in the third step. The masses, spring value, and damping value of the defined user’s structure model
of the second step can be found through the comparison of the masses’ movement (velocity) of the power tool in this
overall system simulation and those measured in real application with the user.
Fig. 2: The three steps to develop a hand-arm model for a direct fastening device
Results
With the presented method, it is possible to parameterize a durable and test-rig-suitable hand-arm model that
is valid for simulating responses to high acceleration caused by impulses. Furthermore, it has been shown that the
user-power tool interaction, in case of impulsive movements, can be modeled as a linear lumped-parameters model.
The parameters of this user replacement model were determined to develop a test rig for power tools. Despite
differences in users’ statures, it is possible to simulate different repercussions by only varying the model masses. The
parameters of the spring-damping-system can be left unchanged. The parameter of the second mass (m2) differs by
0.4 kg, and the parameter of the first mass (m1) differs by 0.5 kg in two exemplary users using a constant contact
pressing force of 20 N.
References
1. Rakheja, S., Wu, J. Z., Dong, R. G., Schopper, A. W. (2002). A comparison of biodynamic models of the human
hand-arm system for applications to hand-held power tools. J. of Sound and Vibration 249(1): 55-82
2. Griffin, M. J. (1990). Handbook of human vibration. London: Academic Press.
3. Dong, R. G., Welcome D. E., Xueyan, X. S., Warren, C., McDowell, T. W., Wu, J. Z. (2012). Modeling of the
biodynamic responses distributed at the fingers and palm of the hand in three orthogonal directions, J. of Sound
and Vibration 332(4): 1125-1140.
79
A METHOD TO DESIGN A HAND-ARM MODEL WITH TRANSLATIONAL AND ROTATIONAL
DEGREES OF FREEDOM FOR HIGH ACCELERATED APPLICATIONS
- A CASE STUDY WITH HAND HELD POWER TOOLS -
Sven Matthiesen , *René Germann , Sebastian Mangold
IPEK – Institute of Product Engineering, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
Introduction
This paper addresses the problem of describing the human hand-arm-system accelerated by high impact
forces in two directions. For this purpose, a method for describing the dynamic behavior of the hand-arm-system in
one direction was extended in this study.
Highly accelerated power tools, such as bolt setting devices, are influenced by very high loads during their
use. Because the loads are partially from the intensive interaction between a user and the power tools, the life
expectancy and functionality of the power tool may significantly depend on that interaction. Therefore, an accurate
description of the influence caused by the user on power tools is very important in the product design process. One
possibility to describe the interactions between the user and a power tool is the use of the mechanical impedance1. In
order to measure this, the force between the user and the power tool and the velocity at the handle have to be measured
with accelerometers and force sensors. Analyzing highly accelerated power tools with these modifications leads to
strong measuring inaccuracies due to the sensor apparent masses. Therefore, in case of highly accelerated power tools,
it is necessary to use a method that modifies the masses as little as possible. Describing the discovered interactions
between the user and the power tool can be done with a physical hand-arm-model which consists of rigid bodies
connected to spring and damper elements. With such models, it becomes possible to design a test rig which interacts
like a hand-arm-system with the tool and analyze the behavior of highly accelerated power tools under realistic,
reproductive conditions. This paper presents an approach to identify the structure and the relevant parameters of such
a model.
Methods
To develop a well-working test rig for highly accelerating power tools, it is necessary to define some
boundary conditions that keep the development of the hand-arm-model into defined limits. These boundary conditions
imply, for the transformation of the hand-arm-model into a test rig, a design with as little complexity as possible,
realistic weights and a realistic response2. Matthiesen et
al.3 developed a method that enables analyzing highly
accelerated power tools with very little modifications.
The method is based on the theory that any user
influence will lead to specific movement of the power
tool’s masses. Furthermore, Matthiesen et al.3 has
shown that the influence of the user can be measured
through the comparison of the tool actuated with or
without the user. Therefore, the movements of the
masses in these two cases have to be measured, and the
difference can be evaluated. The difference in
movement is equal to the forces applied by the user.
However, Matthiesen et al.3 presented this method (Figure 1) only for translational movement of highly accelerated
power tools in their main direction. Many power tools do have an additional rotational or translational movement,
which leads to the need of hand-arm models valid for planar motion. Therefore, the method gets extended in this paper
by analyzing the movement of a direct fastening device’s masses in the translational and rotational directions. Based
on the method shown in figure 1, it is necessary to analyze the movements of the power tool’s masses without a user’s
influence. This can be achieved by little modifications in the tool so that it can be actuated without any user influence.
During the experiment, the movements of the power tool’s masses are filmed by a high-speed camera system. Making
use of tracking software, which is able to track the global and inner displacement of the device during the test case, it
is possible to describe the movement of both the handle and the whole power tool. Those movements can be described
in a rigid body simulation model. The model therefore has been implemented in Matlab Simulink® - valid for free
movements in plane – and has been iterated as long as simulated masses movements fit the measured ones. To describe
the behavior of the power tool with the influence of the user, the experiment is repeated with the modified power tool
Figure 1: Method for analyzing the influence of the user
with high accelerated power tools
Simulation model of the complete system power tool with user interaction
Simulation model of the power
tool
Analyzing the power tool
without the user
Analyzing the power tool with the user
80
but this time, it is operated by the user and analyzed by the high speed camera system again afterwards. According to
the method shown in figure 1, the influence of the user is now equal to the difference between the measured data with
the user and the simulated data of the power tool’s model. A hand-arm-model, which has an equivalent output as the
hand-arm-system, has to influence the masses’ movements of the simulated power tool in a way that is equivalent to
the measured data of the power tool with the user. Under consideration of the boundary conditions, it is possible to
design a hand-arm-model that consists of rigid bodies, translational and rotational connectors, and several spring and
damper elements.
Results and Discussions
The developed model of the hand-arm-systems is displayed in figure 2. It consists of three masses connected
by springs and dampers. The translational spring / damper system cGH / dGH is responsible for a delayed force
transmission from the power tool to the rest of the model, which is equivalent to the realistic response of the power
tool. The connection between this spring/damper system and mass m1H has a rotational degree of freedom. The masses
m1H, m2H and m3H are connected together with a spring-mounted and damped rotational degree of freedom by the
constants cHA / dHA. The connection to the model ground is implemented with the spring / damper system cAD / dAD.
In combination with the power tool’s model, a simulation model of the complete system power tool and user model
can be created. Once more, this overall model has been iterated until simulated movements of the power tool masses
fit the measured ones.
Figure 2: Rigid body simulation modell of the
hand-arm-system
Figure 3: Measured and simulated velocity for one user –
above: main setting direction , below: offset direction
The designed model meets the requested boundary conditions of a simple rigid body model and is able to
accurately simulate the influence of one specific user on a power tool. The presented method is able to define an
explicit structure and the fitting parameters for a model of a highly accelerated hand-arm-system. Figure 3 displays
the simulation results of the main setting and the offset direction in comparison to the measured data. A distinctive
feature of the model is the universal adaptability to different users. By adjusting the parameters of the model, it is
possible to simulate the system with one fixed structure for different users. Afterwards, the simulation model can be
transferred into a test rig. When analyzing more complex applications, further investigations are required to explore
the three-dimensional simulations of these applications. It will also be challenging to create a biomechanically-
motivated hand-arm-model that is suitable for simulating different hand-arm postures.
References
1. Suggs, C. W., Abrams, C. F. (1971): Mechanical impedance techniques for evaluating the dynamic characteristics
of biological materials. Journal of Agricultural Engineering Research 16 (3): 307–315.
2. Dong, R. G., Welcome, D. E., Wu, J. Z., McDowell, T. W. (2008): Development of hand-arm system models for
vibrating tool analysis and test rig construction. Noise Control Engineering Journal 56 (1): 35–44.
3. Matthiesen, S., Schäfer, T., Mangold, S. (2012): Modelling and Simulation of the Hand-Arm-System during
Impact Influences. ASME International Mechanical Engineering Congress and Exposition, Volume 2:
Biomedical and Biotechnology: 909–918.
0 0.005 0.01 0.015 0.02 0.025 0.03-1
-0.5
0
0.5
1
time in s
velo
city in
m/s
measured
simulated
0 0.005 0.01 0.015 0.02 0.025 0.03-2
-1
0
1
2
time in s
velo
city in
m/s
measured
simulated
Offset direction
Main setting
direction
81
Session VII: Combined Exposures and Health Effects
Chair: Ron House and Danny Riley
Presenter Title and authors Page
Tammy Eger Keynote 2: Understanding the link between occupational
exposure to foot-transmitted vibration and the
development of vibration induced white-feet
*Tammy Eger Mallorie Leduc, Katie Goggins, Aaron
Thompson, and Ron House
82
Enrico Marchetti Combined effect of noise and hand-arm vibration
exposures on the cochlear function
Tirabasso A., Botti T., Lunghi A., Di Giovanni R., Sacco
F., Marchetti E., Cerini L., Sanjust F. , Moleti A., Sisto R.
84
Alice Turcot The challenging diagnosis and management of thoracic
outlet syndrome in HAVS syndrome
Alice Turcot and Jessica Ruel-Laliberté
86
Enrico Marchetti Muscular sync and hand-arm fatigue
L. Fattorini, A. Tirabasso, A. Lunghi, R. Di Giovanni, F.
Sacco, E. Marchetti
88
82
UNDERSTANDING THE LINK BETWEEN OCCUPATIONAL EXPOSURE TO
FOOT-TRANSMITTED VIBRATION AND THE DEVELOPMENT OF
VIBRATION-INDUCED WHITE-FEET
*Tammy Eger+,++ Mallorie Leduc+, Katie Goggins+,
Aaron Thompson+++,++++, and Ron House+++,++++
+Centre for Research in Occupational Safety and Health, Laurentian University, Sudbury ON, Canada ++School of Human Kinetics, Laurentian University, Sudbury, ON, Canada
+++Department of Medicine, Division of Occupational Medicine, University of Toronto, Toronto, ON, Canada ++++Department of Occupational and Environmental Health, St. Michael’s Hospital, Toronto, ON, Canada
Introduction
Workers in a number of industries are exposed to vibration that is transmitted into their
bodies through the feet. For example, jumbo drill operators in mining, crusher operators in
construction, and all-terrain-vehicle drivers in agriculture are commonly exposed to foot-
transmitted vibration (FTV). This paper will review current knowledge regarding the development
of vibration-induced white-feet (VWFt) by examining clinical evidence and findings from field
and laboratory studies investigating FTV.
Findings from Clinical Studies
Recent evidence suggests workers exposed to FTV can develop a medical condition
analogous to hand-arm vibration syndrome (HAVS). A worker with VWFt may present with
numbness and tingling in their toes/feet, and cold induced blanching in their toes1. However, data
on VWFt are limited as previous research suggested workers who had vascular problems in the
feet were likely experiencing symptoms secondary to vascular damage associated with exposure
to hand-arm vibration2. Two cases offer evidence which supports the development of VWFt
independent of exposure to hand-arm vibration1,3. In one case, a mink farmer exposed to FTV from
contact with the pedal of an agricultural tractor developed cold-induced blanching in his foot3 and
in the second case a miner with exposure to FTV from operating a bolter was diagnosed with
VWFt1. Neither worker had symptoms compatible with HAVS.
Findings from Field Studies
Field measures documenting the characteristics of occupational exposure to FTV are
limited and have emerged primarily from the mining industry with researchers reporting FTV
exposure associated with the operation of locomotives, bolters, jumbo drills, raise platforms, pit
drill/platforms, cavo loaders, scissor lifts, and crushers4-7. ISO 2631-1 frequency weighted r.m.s
acceleration magnitudes reported (vertical axis) range from a high of 2.62 m/s2 for the Cavo
loader8, to 0.84 m/s2 when drilling off a raise platform5, to 0.76 m/s2 when driving a locomotive6,
to 0.45 m/s2 when operating a bolter6, and to a low of 0.22 m/s2 when standing on a crusher
platform5. However, it might be more relevant to consider vibration exposure frequency, and not
just magnitude, when determining injury risk. When miners were asked to report symptoms of
pain/ache/discomfort in the feet 33% of the surveyed locomotive operators (exposed to FTV with
a vertical axis dominant frequency below 5Hz) reported symptoms while 75% of the raise
operators (exposed to vertical axis FTV with a 40 Hz dominant frequency) reported symptoms5.
Furthermore, in a study of 27 miners six had symptoms of VWFt and all six drilled off a raise
83
platform (40 Hz dominant frequency)7. In 2011 Leduc and colleagues4 reported miners exposed to
FTV with a vertical axis dominant frequency of 31.5 Hz (Jumbo Driller) and 40 Hz (raise platform
driller) had symptoms of VWFt and the bolter operator described in the case study by Thompson
et al., 2010 was also exposed to FTV (40Hz dominant frequency)1. Although not conclusive as
some of the operators in the Leduc study also had a history of hand-arm vibration exposure, these
data suggest workers exposed to FTV in the 30-40Hz range could be at an increased risk of
developing VWFt.
Findings from Laboratory Transmissibility Studies
In a recent laboratory study9 vibration transmissibility was measured from the floor
(vibration platform surface) to the top of the greater toe (first metatarsal) and the floor to the ankle
(medial malleolus) for FTV with a dominant frequency of 25, 30, 35, 40, 45, and 50 Hz. Floor to
ankle transmissibility magnitude was greatest at 30Hz and floor to toe transmissibility magnitude
was greatest at 50Hz. Harazin and Grzesik10 evaluated vibration transmissibility from the floor to
the metatarsus, ankle, knee, hip shoulder and head at frequencies ranging from 4–250 Hz in 1/3
octave bands. They found the magnitude of vibration transmitted by the foot was amplified in the
frequency range of 31.5-125Hz at the metatarsus and 25-63Hz at the ankle.
Summary and Future Research
This review offers evidence from clinical, field and laboratory studies that suggest workers
exposed to FTV are at risk of developing VWFt. Moreover, injury risk appears to be greater in
workers exposed to FTV in the 30-40 Hz range. Further research is required to characterize
resonant frequencies for different regions of the toes, foot and lower limb with an aim to develop
exposure guidelines for workers and controls to protect workers from exposure to FTV frequencies
and magnitudes associated with injury development.
References
1. Thompson, A., House, R., Krajnak, K., and Eger, T. (2010). Vibration-white foot: a case report. Occupational
Medicine, 60, 572-574.
2. House, R., Jiang, D., Thompson, A., Eger, T., Krajnak, K., Sauve, J., and Schweigert, M. (2011). Vasospasm in
the feet in workers assessed for HAVS. Occupational Medicine, 61, 115-120.
3. Tingsgard I, Rasmussen K. (1994). Vibration-induced white toes. Ugeskr Laeger. 156, 4836-4838
4. Leduc, M., Eger, T., Godwin, A., Dickey, J.P., and House, R. (2011). Examination of vibration characteristics
and reported musculoskeletal discomfort in workers exposed to vibration via the feet. Journal of Low Frequency
Noise, Vibration and Active Control. Vol 30(3), 197-206.
5. Eger, T., Thompson, A., Leduc, M., Krajnak, K., Goggins, K., Godwin, A., and House, R. (2014) Vibration
induced white-feet: Overview and field study of vibration exposure and reported symptoms in workers. WORK:
A Journal of Prevention, Assessment & Rehabilitation 47(1): 101-110
6. Eger, T., Salmoni, A., Cann, A., and Jack, R. (2006). Whole-body vibration exposure experienced by mining
equipment operators. Occupational Ergonomics, 6(3/4), 121-127.
7. Hedlund, U. (1989). Raynaud’s Phenonmenon of fingers and toes of miners exposed to local and whole-body
vibration and cold. International Archives of Occupational and Environmental Health, 61, 457-461.
8. Ouellette, S., and Marcotte, P. (2010). Mine workers exposure to noise and vibrations. Report for SOREDEM
(CANMET-MMSL 10-010(J).
9. Goggins, K., Godwin, A., Boudreau-Lariviere, C., and Eger, T. (2014). Examination of vibration
transmissibility from floor to metatarsal and floor to ankle between 25 and 50hz. 5th American Conference on
Human Vibration, Guelph, ON, June 10-13.
10. Harazin, B. & Grzesik, J. (1998). The transmission of vertical whole-body vibration to the body segments of
standing subjects. Journal of Sound and Vibration, 215(4), 775-787.
84
COMBINED EFFECT OF NOISE AND HAND-ARM VIBRATION EXPOSURES
ON THE COCHLEAR FUNCTION
A. Tirabasso+, T. Botti+, A. Lunghi+, R. Di Giovanni+, F. Sacco+, *E. Marchetti+,++, L. Cerini+,
F. Sanjust +, A. Moleti+++, R. Sisto
+INAIL Research, Department of Occupational and Environmental Medicine, Epidemiology and Hygiene
++Sapienza University of Roma, Department of Physiology and Pharmacology “V. Erspamer” +++University of Roma Tor Vergata, Department of Physics, Rome, Italy
Corresponding author: [email protected]
Introduction
Epidemiological studies1,2 and animal3 experiments pointed out a synergistic interaction of
mechanical vibration and noise exposure in inducing hearing impairment4. From the
epidemiological point of view, the evidence of this synergistic effect is quite well assessed;
however, there is still uncertainty of the mechanistic explanation of this phenomenon.
Until now, experiments on human subjects have been performed using audiometry as the
unique test for hearing status assessment. The audiometric test suffers from some limitations,
because it is based on the active collaboration of the subject. Recently, a more objective technique
has been proposed that is based on biomarkers of the cochlear functionality: the otoacoustic
emissions (OAEs).
The present paper studies the combined HAV and noise effect on human subjects in the
laboratory and makes use of OAEs to assess changes of the cochlear functionality in relation to
the exposure condition.
Methods
OAEs are spontaneous or evoked sounds generated by the inner ear. They propagate back
toward the ear canal where they can be recorded by a sensitive microphone. Since OAEs are the
effect (linear and nonlinear) of cochlear activity, they provide information about the cochlear
performance. Twelve normoacusic volunteers were randomly exposed to 1) HAV only, 2) noise
only, and 3) HAV plus noise. Before exposure, all subjects were screened by means of standard
pure tone audiometry and DPOAE (Distortion Product OAE) test with high frequency-resolution.
DPOAEs have been recorded with and without contralateral acoustical stimulation (CAS) of 80
dB SPL in order to assess the exposure effects on the medial olivo-cochlear (MOC) efferent
system. The CAS suppresses the OAE amplitude in normoacusic young non-exposed subjects. In
the condition, 1) each volunteer was exposed on his right side to HAV of 30 m/s2rms acceleration
at 60 Hz for 3 minutes (RMS Shaker plus handle for grip force measuring). The grip force that the
subject was required to sustain was 20% of the maximum voluntary contraction (MVC). During
exposure to HAV, the subject wore ear muffles in order to be insulated from the background noise
produced by the shaker. In the condition 2) the subject was exposed to white noise (0-10 kHz, 95
dBA) by a loudspeaker probe inserted in the right ear canal.
The exposure to noise and HAV was obtained by combining conditions 1) and 2). Each
exposure condition was repeated 5 times, and during exposure intervals, DPOAEs were recorded
85
in the right ear canal. After the last exposure, DPOAE and audiometric tests were performed.
Finally, DPOAEs were recorded every 10 minutes for half an hour during recovery. A suitable,
time-frequency wavelet analysis has been carried out to separate DPOAE distortion and reflection
components. A paired student’s t test was performed to assess the statistical significance of the
differences in each frequency band.
Results and Discussion
Statistical significance for pre-post audiometry comparison was negative in all conditions.
Statistical significance for pre-post DPOAE amplitude comparison was negative in the case of
condition 2) but positivefor some frequency bands in conditions 1) and 3). The two exposure
conditions, HAV only and combined HAV and noise, gave statistically significant pre-post
differencesin the mid frequencies, particularly at
3605 Hz. The two conditions gave opposite
effects: in the case of HAV only, there was an
increase, while in the case of a combined exposure,
there was a decrease in DPOAE amplitude (see
Fig. 1). After 30 minutes of the last exposure, full
recovery could be observed in all cases. These
results deserve to be investigated with a larger
sample. Moreover, in order to ascertain the
mechanistic interaction of noise and vibration in
inducing effects on the cochlear’s function, it is
important to follow the transmission of HAV from
the entering point to the inner ear.
Figure 1. Differences between post-exposure (exp) or
recovery (rec) and pre-exposure (pre) DPOAE amplitudes
without (A) and with (B) CAS (averaged on 12 subjects and
in the frequency band centered at 3605 Hz) measured in
Vibration (V) and Noise&Vibration (NV) condition. Stars
indicate significant differences between pre- and post-
exposure DPOAE amplitude.
References
1. Pyykkö, I., Starck, J., Färkkilä, M., Hoikkala, M., Korhonen, O. and Nurminen, M. Hand-arm vibration in the
aetiology of hearing loss in lumberjacks, British Journal of Industrial Medicine, 38, 281-289, (1981).
2. Pyykkö, I., Starck, J. and Pekkarinen, J. Further evidence of a relation between noise-induced permanent threshold
shift and vibration-induced digital vasospasm, American Journal of Otolaryngology, 4, 391-398, (1986).
3. Zou, J., Bretlau, P., Pyykkö, I., Starck, J. and Toppila, E. Sensorineural Hearing Loss after Vibration: an Animal
Model for Evaluating Prevention and Treatment of Inner Ear Hearing Loss, Acta Oto-laryngologica, 121, 143-
148, (2001).
4. Zhu S., Sakakibara S., Yamada S. (1997). “Combined effects of hand-arm vibration and noise on temporary
threshold shifts of hearing in healthy subjects,” Int. Arch. Occup. Environ. Health 69, 433-436.
86
THE CHALLENGING DIAGNOSIS AND MANAGEMENT OF THORACIC OUTLET
SYNDROME IN HAVS SYNDROME
*Alice Turcot, Jessica Ruel-Laliberté
Institut national de santé publique du Québec, Québec, CANADA
Introduction
Thoracic outlet syndrome (TOS) is defined as a group of symptoms that result from the entrapment
of the brachial plexus and/or subclavian vessels in the thoracic outlet region, between the neck and the
axilla. There are 3 types of TOS, depending on which structure is compressed: neurogenic (brachial plexus),
venous (subclavian veins, 4%–5%) and arterial (subclavian artery, 1% of cases). The most common type is
neurogenic which accounts for more than 90% of cases. The neurogenic type can be subdivided into true
neurogenic and disputed neurogenic, depending on whether nerve conduction studies show changes or not,
respectively. The prevalence is also debated and varies with the clinical location where the diagnosis is
made and with the medical specialty of the treating physician. According to Edwards,2 it is estimated at
approximately 10 cases per 100,000 for all of the types. TOS patients present symptoms that may overlap
or mimic hand-arm vibration syndrome (HAVS), such as hand weakness, loss of dexterity, pain,
paresthesia, fatigue or Raynaud’s phenomenon. Furthermore, the differential diagnosis of TOS is extensive,
including cervical radiculopathy, peripheral nerve entrapment, and shoulder pathology. Accurate diagnosis
is difficult due to the absence of clearly defined diagnostic criteria. TOS was described for a group of
workers suffering from white fingers related to hand-arm vibration.
The purpose of this presentation is to review the controversy surrounding the diagnosis and
management of TOS, to review the etiologies with special regard to work-related risk factors and vibrating
tools, and to present the results of an analysis that explores whether workers with a combined diagnosis of
TOS and white fingers have a different clinical presentation than those with only a white finger diagnosis.
Two clinical cases of TOS identified in the database will also be presented.
Methods
We searched OVID SP (EBM Reviews-Cochrane Central Register of Controlled Trials May 2013,
EBM Reviews-Cochrane Database of Systematic Reviews 2005 to April 2013, Ovid MEDLINE(R) 1946
to 2013, Global Health 1973 to 2013) in French and English focusing on TOS, diagnosis, work-related risk
factors, and treatment (review, meta-analysis). A total of 462 articles were retrieved. One database was also
analyzed, by paying particular attention to the clinical presentation, diagnostic tests and functional
limitations. The participants in this study come from a database of people who applied for compensation to
the Commission de la Santé et de la Sécurité du Travail (CSST, Quebec workers’ compensation board)
between 1993 and 2003. Three hundred and forty-three (344) individuals with white fingers were thus
included in the study. From this same database, 42 simultaneously had TOS and white fingers. Their
characteristics were thus compared to the 302 individuals with white fingers only.
Results and Discussions
To date, very few studies have compared the clinical presentation of subjects with a combined
diagnosis of TOS and HAVS to those with only HAVS. TOS has been described as linked to a combination
or not of constitutional factors (cervical rib, etc.) coupled with muscular dysfunction and repetitive trauma.
However, few epidemiological studies on the prevalence or incidence of TOS among workers from different
87
economic activity sectors or even dealing with the analysis of ergonomic risks related to TOS have been
described. TOS has been described for workers exposed to hand-arm vibration among workers on a
shipyard or construction site)3,4. TOS has been described for symptomatic subjects, namely musicians,
archers, swimmers or for sports requiring a prolonged awkward posture. A diagnosis of TOS and its
treatment remain controversial, and for some, TOS (neurogenic) is a highly overdiagnosed condition and
is treated all too frequently with unnecessary and potentially harmful surgery without an objective, clinical,
radiographic, and electrophysiological basis. There are few randomized studies that compare the surgical
approach to the conservative approach. Many more articles deal with the surgical approach in the treatment
of TOS. However, one notes a consensus that a conservative approach is offered first, followed by the
surgical approach when the conservative treatment fails.5
Analysis of the database reveals that subjects suffering from TOS and white fingers are not different
from workers with white fingers for the type and number of vibrating tools, past exposure to vibration, and
the economic activity sector. Different diagnostic terms are used by clinicians to describe TOS. The TOS
sub-type is not described; it is assumed that it is neurogenic. Fifty-seven percent (57%) of people with
combined TOS present one of the clinical tests for positive thoracic outlet compared to 18.5% of those with
white fingers (OR=5.16; CI (95%): 2.45-10.89; p-value < 0.001, adjusted for years of exposure to
vibration). Although, the information is not available for 124 workers with white fingers only. The TOS
diagnosis is not retained consensually in all of the cases. The clinical presentation of the two groups is
comparable, in terms of presence of white fingers, functional limitations and the anatomopathological
deficits assigned. Also, specific recommendations regarding the functional limitations related to TOS are
not given. Eighty-one percent (88.1%) of people with combined TOS present numbness compared to 76.6%
of the people with white fingers alone (OR=3.42; CI (95%): 1.01-11.57; p-value =0.048, adjusted for years
of exposure to vibration). Carpal tunnel syndrome is described in 22.0% of workers with TOS compared to
23.6 % of workers with white fingers (OR=0.87; CI (95%): 0.38-2.01; p-value=0.748 adjusted for years of
exposure). Little surgery is offered to subjects with TOS.
Considering the nature of the study, research should be pursued before concluding that there are
differences in the clinical presentations. The work-related etiological factors of TOS are not studied
systematically, but should be. Carpal tunnel syndrome present in HAVS could be secondary to the presence
of compression higher up, as described in double crush syndrome, but further studies are needed. TOS
diagnosis should therefore be systematized in a medical protocol, and a consensual definition of the disease
is necessary. There is a need to describe the prevalence of the disease in workers in order to understand the
role of ergonomic stressors and vibration, and thus produce appropriate recommendations for treatment.
References
1. Klaassen, Z., Sorenson, E., Tubbs, R.S., Arva, R., Meloy, P., Shirk, S., and Loukas, M. (2014). Thoracic outlet
syndrome: a neurological and vascular disorder. Clinical Anatomy 27(5): 724-732.
2. Edwards, D., Mulkern, E., Raja, A., and Barker, P. (1999). Trans-axillary first rib excision for thoracic outlet
syndrome. Journal of the Royal College of Surgeons of Edinburgh 44(6): 362-365.
3. Letz, R., Cherniack, M.G., Gerr, F., Hershman, D., and Pace, P. (1992). A cross sectional epidemiological survey
of shipyard workers exposed to hand-arm vibration. British Journal of Industrial Medicine 49(1): 53-62.
4. Hagberg, M. (2002). Clinical assessment of musculoskeletal disorders in workers exposed to hand-arm vibration.
International archives of occupational and environmental health 75: 97-105.
5. Povlsen, B., Belzberg, A., Hansson, T., and Dorsi, M. (2010). Treatment for thoracic outlet syndrome (Review).
Cochrane Database of Systematic Reviews. Published in The Cochrane Library Issue 1.
88
MUSCULAR SYNC AND HAND-ARM FATIGUE
L. Fattorini+, A. Tirabasso++, A. Lunghi++, R. Di Giovanni++, F. Sacco++, *Enrico Marchetti+,++
+Sapienza Università di Roma, Department of Physiology and Pharmacology “V. Erspamer”, Rome, Italy ++National Institute for Insurance against Accidents at Work
Department of medicine, epidemiology, workplace and environmental hygiene, Rome, Italy
Introduction
Muscular fatigue is a topic that deserves greater attention in a world that has made an even greater
use of vibrating tools. Since, 1997, when Martin and Park1 introduced a measuring parameter of muscular
synchronization with the external mechanical vibration frequency, there have been few developments on
the consequences of this synchronization. The presence of an external, mechanical, and rhythmic stimulus
induces a coherent activation of most muscular fibers (e.g., motor unit synchronization) which may impair
the physiological muscular activation while performing the motor task. The Sync level (SL) is defined as
the spectral power density integrated around the mechanical vibration frequency and then divided by the
integral of the whole spectral density. The present work is aimed to both assess the relationship between
SL and fatigue and reproduce the standard experimental conditions similar to those met in field.
Methods
The experiment consisted of exposing the hand-arm system (HAS) to vibration at various
frequencies and grip forces, and comparing the assessed parameters without mechanical vibration (MV).
Sixteen subjects, 9 females and 7 males, participated in the experimental study. MV on the handle was
elicited by an electrodynamic shaker (RMS SW 1508, Germany, EU) driven by a controller (Vibration
Research VR 7500-2, Germany, EU) at 20, 30, 33 and 40 Hz. The signal had a constant velocity of 27
mm/s. In order to take into account interpersonal differences, the exerted grip force(GF) was expressed in
terms of Maximum Voluntary Contraction (MVC). In the motor task, the participant maintained a grip force
of20, 30, 40, and 60 % MVC on the dominant hand for 45 seconds. The posture was standardized in
accordance with the UNI EN ISO 10819 (1998) for glove testing. Muscular activity has been assessed by
surface electromyography (sEMG) of extensor carpi radialis longus (ECRL) muscles. The sEMG was
acquired by the wireless system Zero Wire (Cometa, Italy, EU). Additionally, EMG signals were
transmitted and recorded on the digital analyzer OROS OR38 (Oros, France, EU). Furthermore, data
analysis was performed off-line with ad hoc applications developed with MatLab Release 2008a
(Mathworks, Massachusetts, USA). As reported by Martin1, the SL index was computed at the specific
vibration frequency at the beginning and at the end of the measurement. In this study, delta SL (∆SL) was
defined as a percentage difference of the early exposure (first 3 seconds of steady state of grip force) and
the late exposure (last 3 seconds of exposure). Median frequency decay (MDFd) was evaluated in EMG
windows of 1 second, from which a linear regression was calculated. The MDFd being accountable of the
long term muscular fatiguing response to vibration2 and presents negative values.
Results and Discussions
Studying the ∆SL results, see Fig. 1, while it is evident that a clear relationshipexists at 20, 30, 33
Hz of vibration, this relationship disappear at 40 Hz. Interestingly, only at 20% of MVCshowed an increase
of ∆SL with SV augment. The max value is reached at the max force level and a SV of 30 Hz. When
comparing ∆SL with MDFd (Fig. 2), it is possible to catch a parallel: both parameters have an increase in
frequencies and force. While the SL represents the tendency of muscular fibres to synchronize to the
external vibration frequency, the MDFd is thought to be an indicator of muscular fatigue2.
89
Figure 1: the ∆SL related to vibration frequencies expressed in terms of grip force (% of MVC).
Figure 2: MDFd for the extensor muscle for various frequency and grip force (% of MVC)
In conclusion, it is possible to point out that during long-lasting grip tasks and mechanical vibration
exposure, the muscular fatigue is driven, apart from other factors, by the synchronization of muscular fibres
on the mechanical vibration frequency. Vibration exposures at 30 and 33 Hz seem to be more fatiguing than
others, especially at higher force levels. It is well known that in the range around 30-33 Hz,one of the HAS
resonances3 is present. This resonance mechanic phenomenon has been revealed here by
electromyographical data.
References
1. Martin BJ, Park HS. “Analysis of the tonic vibration reflex: influence of vibration variables on motor
unit synchronization and fatigue”, European Journal of Applied Physiology, 1997;75(6):504–11.
2. De Luca, CJ, “Myoelectric manifestation of localized muscular fatigue in humans”, Crit Rev Biomed
Eng. 1984;11(4):251-79.
3. Marchetti E, Lunghi A, Fattorini L, Nataletti P, Morgia F. Difference between men and women in hand-
trasmitted vibration power absorption.2007, 11th International conference on HandArmVibration,
Bologna
0
20
40
60
80
100
20hz 30hz 33hz 40Hz
De
lta
SL (
%)
SV (Hz)
20%
30%
40%
60%
-0.6
-0.5
-0.4
-0.3
-0.2
-0.1
0
0 20 30 33 40
MD
F d[H
z/se
c]
SV [Hz]
GF20
GF30
GF40
GF60
90
Session VIII: Risk Assessment and Epidemiology
Chairs: Lihua He and Marco Tarabini
Presenter Title and authors Page
Paul Pitts Evaluation of risk for vascular hand-arm vibration injury
– development of a new ISO technical report
Paul Pitts and Anthony Brammer
91
Frank Bochmann Risk assessment of musculoskeletal disorders among
workers exposed to hand-arm-vibration: design, exposure
assessment methods and first results of an
epidemiological case-control study
Frank Bochmann, Uwe Kaulbars, Winfried Eckert, Yi
Sun
93
Per Vihlborg Vibration survey of workers in Swedish mechanical
industry
Per Vihlborg, Ing-Liss Bryngelsson, Lars-Gunnar
Gunnarsson, Pål Graff, Bernt Lindgren
95
Jacek Kuczyński Improved methods of assessment of vibration risk
Jacek Kuczyński
97
Xiangrong Xu A survey on occupational hazards of coal workers using
hand-transmitted vibrating tools in a northern china coal
mine
Xiangrong Xu, Manman Gong, Zhiwei Yuan, Rugang
Wang, Sheng Wang, Lihua He
99
91
EVALUATION OF RISK FOR VASCULAR HAND-ARM VIBRATION INJURY –
DEVELOPMENT OF A NEW ISO TECHNICAL REPORT
*Paul Pitts+, Anthony Brammer++
+Health and Safety Executive (HSE), Harpur Hill, Buxton, UK ++Ergonomic Technology Center, University of Connecticut Health, Farmington, CT, U.S.A., and
Envir-O-Health Solutions, Ottawa ON, Canada
Introduction
Since ISO 5349 was first introduced in 1986 (superseded in 2001 by ISO 5349-11), there have been
concerns raised by technical experts that the prediction of incidence of vascular injury from certain machine
types could be improved.2 The standard seemed to over-predict risk from low-frequency machines like sand
rammers, while perhaps over-predicting risk from machines generating large amounts of high-frequency
energy, such as chipping hammers. In order to address these concerns, the ISO hand-arm vibration Working
Group agreed to consider the options for an alternative frequency weighting for vascular hand-arm vibration
injury and have now produced a new method for evaluation in an ISO Technical Report.
This paper reviews the basis for the proposed frequency weighting and the evaluation methodology
provided in a new draft ISO Technical Report: “Mechanical Vibration — Measurement and evaluation of
human exposure to hand-transmitted vibration — Supplementary method for assessing risk of vascular
injury”.
Justification for new frequency weighting for vascular injury
In 2008 the ISO working group on hand-arm vibration (ISO TC 108 SC 4 WG 3) began work to
define a new frequency weighting for vascular hand-arm vibration injury. A set of candidate weightings
were proposed and publicised3 in order to encourage research into the suitability and limitations of the
different weightings:
• Wh-bl: The band-limiting component of the existing frequency weighting,1 Wh
• W hT: A weighting based on epidemiological data of VWF incidence4
• Whf: A weighting based on finger vibration power absorption5
Investigation of these candidate weightings showed that the differences between WhT and Whf
weighted levels is very small across a cross-section of tool types.3 Assessment of the weightings with injury
showed no strong link to any individual weighting,6 but analysis of the apparent relative risk from selected
machine types was able to demonstrate the case for a vascular injury weighting, encompassing the
frequency range from 20 to 400 Hz.7
Following this work, and on the recommendation of experts attending a workshop on frequency
weightings for vascular injury at the Twelfth International Conference on Hand-Arm Vibration (Ottawa),
the ISO technical Committee agreed to develop a Technical Report. The purpose of this Technical report
would be to:
• define a evaluation methodology that supplements that given in ISO 5349-1, and
• ensure that additional data is collected in a common format to help to improve knowledge and
understanding of vascular vibration risks.
Frequency Weighting Wp and Daily Exposure Threshold
Figure 1 compares Wp (a band-limiting filter between 20 and 400 Hz) with ISO 5349-1 frequency
weighting, Wh. In order to have potential value as a measure that is distinct from Wh, acceleration values
assessed with the Wp weighting should not be strongly correlated with equivalent Wh weighted values.
Figure 2 compares average Wh and Wp weighted acceleration values for 39 tool categories across a range of
92
industries. Analysis shows a statistically significant moderate (Pearson’s r value 0.65) positive correlation
between the two data sets.
Figure 8 Wp and Wh weightings
Figure 9 Comparison of average Wp and Wh weighted
values for a number of different tool categories
To distinguish exposures using Wp from those based on Wh, it is recommended that daily exposure
be assessed as a daily exposure value Ep,d, rather than as an A(8) value. The analysis of Brammer and Pitts
permits an estimate to be made of the smallest daily vibration exposure at which vascular symptoms may
be expected to occur.7 The threshold for the onset and continuing development of white fingers appears to
be in the range: Ep,d = 1150 - 1750 ms-1.5.
It is intended that the new Technical Report be limited to research on vascular hand-arm vibration
injury. It should not be used in place of ISO 5349-1 and data derived from it should not be used instead of
ISO 5349-1 data for fulfilling duties under national regulation, guidance or recommendations for either
workplace vibration exposures or machinery vibration emissions.
Acknowledgements
This publication and the work it describes were in funded by the National Institute for Occupational Safety
and Health under research grant 5R01 OH008997 and the Health and Safety Executive (HSE). Its contents,
including any opinions and/or conclusions expressed, are those of the authors alone and do not necessarily
reflect HSE policy.
References
1. ISO 5349-1 (2001): Mechanical Vibration and Shock – Evaluation of human exposure to hand-transmitted
vibration – Part 1 General requirements, International Organization for Standardization, Geneva, Switzerland.
2. Griffin, M.J., Bovenzi, M., and Nelson, C.M. (2003). Dose-response patterns for vibration-induced white finger,
Occupational & Environmental Medicine, 60, 16-26.
3. Pitts, P.M. (2010). Evaluation of candidates for additional frequency weightings for hand-arm vibration
measurements. VDI-Berichte, 2097, 125-136.
4. Tominaga, Y. (2005). New frequency Weighting of Hand-Arm Vibration. Industrial Health, 43, 509-515.
5. Dong, R.G., Welcome, D.E., McDowell, T.W., Xu, X.S., Krajnak, K., and Wu, J.Z. (2012). A proposed theory
on biodynamic frequency weighting for hand-transmitted vibration exposure, Industrial Health 50(5), 412-424.
6. Pitts, P.M., Mason, H.J., Poole K.A., and Young, C.E. (2011). Relative performance of frequency weighting Wh
and candidates for alternative frequency weightings when used to predict the occurrence of hand-arm vibration
induced injuries. Canadian Acoustics, 39(2), 96-97.
7. Brammer, A.J., and Pitts, P.M. (2012). Frequency weighting for vibration-induced white finger compatible with
exposure-response models. Industrial Health, 50(5), 397-411.
93
RISK ASSESSMENT OF MUSCULOSKELETAL DISORDERS AMONG WORKERS
EXPOSED TO HAND-ARM-VIBRATION: DESIGN, EXPOSURE ASSESSMENT
METHODS AND FIRST RESULTS OF AN EPIDEMIOLOGICAL CASE-CONTROL
STUDY
*Frank Bochmann+, Uwe Kaulbars+, Winfried Eckert++, Yi Sun+
+ IFA-Institute for Occupational Safety and Health of German Social Accident Insurrance
Sankt Augustin, Germany ++BG-Bau – Berufsgenossenschaft der Bauwirtschaft, Böblingen, Germany
Introduction
Mechanical vibration arises from a wide variety of processes and operations performed in
industry, such as mining, construction and forestry. Studies from different countries indicate an
elevated risk of musculoskeletal disorders among vibration-exposed workers in compare to non-
exposed workers. In Germany, there are approximately 1.5 to 2 million employees are currently
exposed to hand-arm vibration which may represents a threat to their health. Although the human
responses to vibration depend both on the magnitude and frequency of the vibration signal, their
impacts on human health are poorly investigated. In order to quantitatively evaluate the effects of
frequency dependent hand-arm-vibration on the risk of musculoskeletal disorders of the hand-arm-
shoulder system, an epidemiological case-control-study was conducted among workers in the
construction, mining and metal industries in Germany.
Methods
In total, 250 clinical confirmed cases and 750 controls are recruited by the German Social Accident
Insurance Institutions. The individual work history, its related working activities and the use of
hand-transmitted vibration equipment were collected in a standardized personal interview by
trained and experiences work safety inspectors of the German Social Accident Insurance
Institutions. In addition, a database on the magnitude and frequency spectrum of mechanical
vibrations of commonly used hand-transmitted vibration equipment was established based on
standardized industrial hygiene measurements. Information on relevant confounding factors such
as sports, leisure activities and co-morbidities are also collected in the standardized personal
interview.
94
Results and Discussions
Detailed information on study design, exposure assessment methods, quality control and first
results will be presented.
95
VIBRATION SURVEY OF WORKERS IN SWEDISH MECHANICAL INDUSTRY
*Per Vihlborg+, Ing-Liss Bryngelsson+, Lars-Gunnar Gunnarsson+,++,
Pål Graff+, Bernt Lindgren+++
+Department of Occupational and Environmental Medicine, Örebro University Hospital,
Sweden ++School of Medicine, Örebro University, Sweden
+++Feelgood Occupational Health Unit Hallsberg, Sweden
Background
Working with handheld vibrating tools is common in the Swedish industry and one of the
main causes of occupational disease. There are well known effects on vascular, neurological and
musculoskeletal symptoms in the hands from vibrations.
Aim
Investigate the frequency of vibration related symptoms in a mechanical industry. The
workers got information about adverse health from vibrations and some also got a medical
intervention, we then did a follow up 3 years after the initial investigation.
Methods
This report is based on examinations performed at an occupational health service of
workers at a company in a mechanical industry unit.
66 out of 68 persons underwent hearing tests and 24 persons also presented symptoms
suggestive of hand-arm vibration syndrome (HAVS). Those 24 persons where offered a medical
examination.
The medical examination consisted of questionnaires regarding symptoms and exposure,
standardized medical examination and in selected cases, quantitative sensory testing (QST)
accomplished at the Department of Occupational and Environmental Medicine, Örebro University
Hospital.
The exposure to vibrations has been measured and estimated below 2,5 m/s2.
Results
Of the total of 23 people that was medical examinated 21 had problem with white fingers,
neurological symtom includning carpaltunnel syndrome. 13 of the 23 person examinated had both
neurlogical symtoms and white finger. Subjects studied were judged to have HAVS. QST was
conducted on the workers with suspected vibration syndrome or other comorbidity and A third of
those surveyed showed signs of carpal tunnel syndrome (CTS)
No significance was found between exposure time, age and place of work. There was no
excess risk for HAVS among those who were snuff users compared to non-users. There was
significant excess risks (OR 23,3 95% CI: 1,12-458) for white fingers for the welders compere to
96
other workers when data were adjusted for snuff habits and exposure time compere to other
workers.
The follow-up examination three years later showed equal symptom prevalence except on
those with CTS which had improved after surgery. Where 4 patients showed no symptoms after
surgery.
Conclusion
This study shows that HAVS is common in blue collar workers exposed to vibrations even
if the vibration exposure is not very high. Symptoms of HAVS were stationary between surveys
even if the workers were informed of the adverse health effects from vibration exposure. The study
shows the importance to carry out reoccurring medical checks in employment (MKA) to find
people with CTS and other vibration related symptoms to reduce negative impact from work
environment.
97
IMPROVED METHODS OF ASSESSMENT OF VIBRATION RISK
Jacek Kuczyński
International Marketing Manager, Svantek, Poland
Introduction
Measurement methods described in ISO 5349-1 and
ISO 5349-2 are subject to a high level of uncertainty (±20% to
40%) due to the estimation of daily exposure time. The only
right solution to decrease the level of this uncertainty is the use
of daily vibration exposure meters (DVEM). Similar to noise
dosimeters, daily vibration exposure meters must be small
enough to be worn and must not interfere with normal working
activities. ISO 5349-2 mentions that contact force measurement
should be used to detect when the worker's hands first make
contact with the vibrating surface and when contact is broken.
With the development of the new and very small MEMS
sensors, it became possible to situate the force sensor beside the
vibration accelerometer. This solution allows the user to both
automatically obtain information about the period while the
hand is in contact with the vibrating surface and evaluate the
total contact time per day.
Methods
The study was performed with the SV 103 (Svantek Sp. Z o.o., 2014), SVANTEK’s new
vibration exposure level meter that meets ISO 8041:2005 and was designed to perform
measurements in accordance to ISO 5349-1 and ISO 5349-2 with special adapters mounted on the
operator's hand. The task was to drill four holes in a reinforced concrete block, and this was
performed by 3 operators. Each operator drilled the first two holes without gloves and the next two
holes with ISO 10819:1996 certified anti-vibration gloves on. The task was performed with the
hammer function of the drill enabled (a model DeWALT D25103 with a manufacturer stated
vibration amplitude of 9.2 ms-2 in accordance to IEC 60745).
Results and Discussions
Results of A(8) for each operator show the relation between contact force values and
vibration magnitudes. Therefore contact force should be taken into consideration when evaluating
the daily exposure.
The analysis of the 1/3 octave spectrogram proved selection of exposure times to be correct
and additionally helped to evaluate the efficiency of anti-vibration gloves usage. The spectrogram
clearly showed 4 activities for all operators, however the spectrum for Operators 1 and 3 contained
lesser values on higher frequencies for the last two drills which resulted from the use of anti-
vibration gloves. Despite the use of anti-vibration gloves, the spectrogram for Operator 2 (Figure
2) showed every hole drilled at a similar frequency content. These results show that an increase of
contact force may significantly reduce the efficiency of anti-vibration gloves.
Fig. 1: SV 103 Vibration
dosimeter
98
Table 1: Measurement results for 3 tasks
Operator Force threshold
N
Exposure time
mm:ss
Vector AEQ
ms-2
A(8)
ms-2
Force Aver
N
1 10 01:41 7.590 0.45 65.3
20 01:31 7.963 0.45 70.9
2
10 02:23 8.659 0.61 93.7
20 02:10 9.023 0.61 101.5
3
10 03:46 8.193 0.73 22.6
20 01:43 9.246 0.55 29.5
Figure 2 Spectrogram of 1/3 octave (Operator 2)
References
1. Jolanta Malinowska-Borowska, Barbara Harazin, Grzegorz Zieliński (2012), Measuring Coupling Forces
Woodcutters Exert on Saws in Real Working Conditions, International Journal of Occupational Safety and
Ergonomics (JOSE) 2012, Vol. 18, No. 1, 77–83
2. International Organization for Standardization (1996) Mechanical vibration and shock -- Hand-arm vibration
-- Measurement and evaluation of the vibration transmissibility of gloves at the palm of the hand, ISO 10819.
3. International Organization for Standardization (2007) Mechanical vibration and shock -- Coupling forces at
the man--machine interface for hand-transmitted vibration, ISO 15230.
4. Technical Report (2012) Mechanical vibration and shock - Hand-transmitted vibration - Influence of
coupling forces at the hand-machine interface on exposure evaluation, CEN/TR 16391
99
A SURVEY ON OCCUPATIONAL HAZARDS OF COAL WORKERS USING HAND-
HELD VIBRATING TOOLS IN A NORTHERN CHINA COAL MINE
*Xiangrong Xu, Manman Gong, Zhiwei Yuan, Rugang Wang, Sheng Wang, Lihua He
Peking University Health Science Center, Beijing, China
Corresponding author: HE Li-hua ([email protected])
Introduction
Hand-transmitted Vibration (HTV), also known as Hand-arm Vibration or Segmental
Vibration, means when using hand-held vibrating tools or vibration artifacts, mechanical vibration
or shock can be transmitted to the hand and arms or act directly on workers. The exposure occurs
in many industrial productions, especially in labor-intensive manufacturing and construction
processes. In recent years, while some reports have focused on the health effects of the hand-
transmitted vibration exposure among workers in the southern part of our country, few studies
reported the exposure effects in the northern part of the country. So, this study is aimed to
investigate and analyze the vibration-induced symptoms of the coal workers who used hand-held
vibrating tools in a northern China coal mine in order to identify the impact of HTV exposure on
coal workers and to provide basic data for further research.
Methods
167 coal workers who using hand-held vibrating tools in a northern China coal mine are as
research subjects. The study received 167 valid questionnaires in total and the response rate is
100%. Subjects are all man, have a mean age of 35.1(SD±7.7) years and have a mean working
years of 5.1(SD±4.1) years.
This study conducted questionnaire investigation, health test, and vibration exposure
measurement. The sense of touch, temperature sensation and pain were measured with the
instruments made by Beijing Orient Long Technologies co., ltd. Besides, we measured hand grip
strength and examined hand and wrist by X-ray test. Human vibration analyzer (Svantek (Poland),
SV 106) was used to measure the intensity of HTV at workplaces with hand-transmitted vibration
exposure. Each workers participated in the test performed three trials at each measurement site.
The average 8h-energy-equivalent frequency-weighted acceleration, A(8), was calculated
according to the newest version of China national standard.
Database was established using Epidata 3.1 software. Double entry and validation was
adopted for all data by specially trained professional person and analysis was carried out by SPSS
16.0. We used Chi-square test and the multi-factor logistic regression analysis. The significance
level was set to 0.05.
Results
1. The intensity of hand-transmitted vibration. 8h-energy-equivalent frequency-weighted
acceleration is calculated as 6.55m/s2, exceeding the national standard which is 3.5m/s2.
2. The occurrence of self-conscious symptoms on hand and wrist. The statistically differences
of the incidence of hand numbness and hand bilges were found in different working years groups
(p<0.05). Comparing these by duration of daily exposure to vibration, we found the incidence of
hand numbness, carpal tunnel syndrome and white fingers have statistically significant differences
100
(p<0.05).
3. The occurrence of self-conscious symptoms on others. The statistically differences of all these
symptoms incidence was not found in different working years groups (p≥0.05). But comparing
these by duration of daily exposure to vibration, we found the incidence of tinnitus, memory loss,
dizziness and headache have statistically significant differences (p<0.05).
4. The Physical Examination Results of coal workers. Comparing the physical examination
results of the different working years groups, we found that the abnormal rate of vibratory sense
(both hands) and the incidence of joint space narrowing have statistically significant difference
(p<0.05). What's more, comparing the physical examination results by duration of daily exposure
to vibration, we found that the differences between the abnormal rate of vibratory sense (the right
hand) and the incidence of osteosclerosis have statistically significant difference (p<0.05).
5. Analysis on risk factors of typical symptoms. The incidence of hand numbness was higher
with the working years growing and the relative risk of 6-9 years group was 9.9 times as much
as that of <3 years group (95%CI:4.75–31.08). The incidence of hand numbness increased with
duration of daily exposure to vibration and the relative risk of 2h-4h group was 36.7 times as much
as that of <2h group(95%CI: 1.61–839.92). Compared with non
drinkers, the risk for hand numbness was 4.6 (95%CI:1.51–14.02) among drinkers. Also,
compared with wearing gloves, the risk for hand numbness was 7.5 (95%CI:2.10–26.65)
among not wearing.
Discussion
The results show that HTV seriously damages workers’ health. The main self-conscious
symptoms were hand numbness, hyperhidrosis palmaris, tinnitus and memory loss. Among these,
the incidence of hand numbness was highest which was 35.5%. The physical examination results
showed that temperature sensation, pain, sense of touch and vibratory sense were abnormal, among
these, the abnormal rate of temperature sensation was highest which was 39.2%.
In this investigation, the incidence of vibration induced white finger was 4.2% which was much
lower than that in drillers of the northeast China (10.1%～45.0%). The main reason is that all the
subjects work at the state owned large coal mine enterprise were required to use the vibration
isolation gloves strictly. Secondly, the average working years are shorter. Thirdly, compared with
the northeast China, local temperature is higher.
The logistic regression analysis was used to analyze hand numbness and we found that
long working years, longer duration of daily exposure to vibration and drinking were risk factors
and wearing the vibration isolation gloves are protective factors. But with increased working years
or prolonged duration of daily exposure to vibration, workers' awareness of HTV hazards will be
enhanced. Therefore the changes were not obvious. Occupational exposure to HTV can do harm
to health. Strengthening protection and lowering intensity should be done to protect workers.
Simultaneously, technical innovation and technological transformation should be taken to
decrease the vibration and reduce the risk.
101
Session IX: Tests for and Diagnosis of Health Effects II
Chairs: Paul Pitts and Ying Ye
Presenter Title and authors Page
Anthony J. Brammer Vibrotactile perception thresholds at the fingertip
measured with and without a surround
Gongqiang Yu, Anthony J. Brammer, Martin G.
Cherniack
102
Yanzhi Liu Ultrasonic observation and the significance of the
patients with hand-arm vibration disease
Yanzhi Liu, Qiongjie Lu, Xiangrong Xu, Zhimin Li,
Lihua He
104
Qingsong Chen The effectiveness of nailfold capillaroscopy in the
diagnosis of hand-arm vibration syndrome among gold
miners
Guiping Chen, Bin Xiao, Maogong Shi, Danying Zhang,
Fansong Zeng, Bei Yang, Hansheng Lin, Xuqin Cao,
Qingsong Chen
106
102
VIBROTACTILE PERCEPTION THRESHOLDS AT THE FINGERTIP MEASURED
WITH AND WITHOUT A SURROUND
Gongqiang Yu+, *Anthony J. Brammer+,++, and Martin G. Cherniack+
+Ergonomic Technology Center, Health Center, University Connecticut, Farmington, CT, USA ++Envir-O-Health Solutions, Ottawa, ON, Canada
Introduction
Techniques for determining the vibrotactile sensitivity of the mechanoreceptor populations at the fingertips
by means of vibrotactile perception thresholds (VPTs) have been codified in international standards (ISO 13091-1,
and 13091-2). Statistically significant associations between vibrotactile thresholds mediated by the SAI, FAI and FAII
receptor populations at the fingertips and symptoms of deteriorating tactile acuity have been reported in a field study
of manual workers (Wakulczyk et al, 1997). Thus, well-defined VPT values for healthy persons provide important
baseline data, since they can be used to examine sensory neuropathies for clinical diagnostic purposes. However,
different equipment and methods for performing vibrotactile measurements might lead to different results. Therefore,
a specially designed instrument has been developed according to configurations specified in ISO 13091-1, and used
to measure mechanoreceptor-specific VPTs at the fingertips. Results are compared between VPTs obtained from
healthy males and females, and between VPTs obtained either with, or without, a surround.
Apparatus and Method
Twelve males (with mean age and SD of 30 ± 6 years) and nine females (aged 29 ± 5 years) who are
employees of UConn Health, with no history of neuromuscular or vascular disorders or of serious injures of the upper
extremities, participated in the tests. VPT measurements were performed using the apparatus designed and
implemented in the authors’ laboratory. The tactometer consists of a stimulator mounted on a vertically adjustable
track; an arm support on which the hand and forearm rest with palm facing upwards (as shown in Figure 1); an
accelerometer attached to the stimulator to sense the motion of a fingertip; electronics to produce short duration stimuli
of known magnitude and to process the motion; and a computer to administer the stimuli and psychophysical
algorithm, and to calculate perception thresholds. For the current study the probe diameter was 3 mm, the surround
diameter 6 mm, the force applied to the probe and surround was 0.6 N, and the nominal skin indentation was 0.5 mm.
The stimulus frequencies were 3.15, 4, 5, 20, 25, 31.5 100, 125, 160 Hz (harmonic distortion was less than 14%).
Intermittent stimulation with a rapid, "1-up-1-
down" stepped algorithm was employed, with a
step size of 2 dB/trial (the step size was initially
6 dB/trial until the subject responded). The
subjects’ skin temperature was 27-35 ºC, and
room temperature was 20-25 ºC.
Figure 1: Sketch of stimulator and fingertip-
probe/surround contact [reproduced from
Figure 1 of ISO 13091-1].
Results and Discussion
VPTs were determined at the middle and little fingers of both hands. VPT values were expressed in dB (re.
10-6 m/s2), and were averaged over the two repetitions of all the four fingers of the same subject. These VPTs were
adjusted to an age of 30 years by applying the values in Table 1 (ISO 13091-2), and to a probe diameter of 4 mm by
reducing the observed thresholds at 100, 125 and 160 Hz by 1.2 dB (Gescheider et al. 2002).
103
Table 1. VPT data age adjustment/year (based on age of 30)
Frequency (Hz) 3.15 4 5 20 25 31.5 100 125 160
Adjust (dB)/year 0.03 0.03 0.03 0.08 0.08 0.08 0.25 0.3 0.35
As shown in Figure 2, this study found that male subjects possess higher (i.e., less sensitive) VPTs than
females at low frequencies (4 and 5 Hz, t-test, p < 0.01), and at high frequencies (100, 125, and 160 Hz, t-test, p <
0.005). In contrast, male and female thresholds at mid frequencies were in agreement. These frequencies are believed
to be mediated by the FAI receptors (anatomical correlate: Meisner corpuscles). As shown in Figure 3, the mean VPTs
for male subjects are in reasonable agreement irrespective of whether the probe has a surround, as shown in "Method
B" of Figure 1 (current study), or does not have a surround, as shown in "Method A" of Figure 1 (data from Brammer
et al, 2007). For the stimulation frequencies that are common to both studies (4, 20, 31.5, 100 and 160 Hz), there is
no statistically significant difference between the mean VPTs (t-test). The study without a surround employed
stimulation conditions identical to those used here except for the contact force, which was 0.05 N.
Figure 2. VPTs of male and female subjects Figure 3. Comparison of VPTs of males
in current study and Brammer at al 2007.
References
1 Brammer, A.J., Piercy, J.E., Pyykkö, I., Toppila, E., and Starck, J. (2007). Method for detecting small changes in
vibrotactile perception threshold related to tactile acuity. J. Acoust. Soc. Am. 121, 1238-1247.
2 Gescheider, G.A., Bolanowski, S.H., Pope, J.V., and Verrillo, R.T. (2002). A four-channel analysis of the tactile
sensitivity of the fingertip: frequency selectivity, spatial summation, and temporal summation. Somatosensory &
Motor Research, 19(2), 114-124.
3 ISO 13091-1 (2001). Mechanical Vibration - Vibrotactile Perception Thresholds for the Assessment of Nerve
Dysfunction - Part 1: Methods of Measurement at the Fingertips. Geneva, International Organization for
Standardization.
4 ISO 13091-2 (2003). Mechanical Vibration - Vibrotactile Perception Thresholds for the Assessment of Nerve
Dysfunction - Part 2: Analysis and Interpretation of Measurements at the Fingertips. Geneva, International
Organization for Standardization.
5 Wakulczyk, G.C., Brammer A.J., and Piercy J.E. (1997). Association between a quantitative measure of tactile
acuity and hand symptoms reported by operators of power tools. J. Hand Surgery, 22: 873-881.
Acknowledgement: Work supported by National Institute for Occupational Safety and Health research grant 5R01
OH008997
104
ULTRASONIC OBSERVATION AND THE SIGNIFICANCE OF THE PATIENTS WITH
HAND-ARM VIBRATION DISEASE
*Yanzhi Liu+, Qiongjie Lu+, Xiangrong Xu+, Zhimin Li+, Lihua He++
+Shenzhen Prevention and Treatment Center for Occupational Diseases, Guangdong, China ++Peking University Health Science Center, Beijing, China
Corresponding author: Lihua He ([email protected])
Introduction
Hand-arm vibration disease (HAVD) is a legal occupational disease in China, which mainly
refers to hand peripheral circulation and (or) hand neurological dysfunction caused by prolonged
intensive exposure to hand-transmitted vibration (HTV) at workplaces. The vibration exposure
may also cause damage to bones, joints, and muscles of the arms. A considerable proportion of
workers suffering from the disease after some years of work using hand-held vibrating tools. Now,
the diagnosis of HAVD mainly depends on the patient’s history and clinical manifestations, less
application of imaging examination. In order to improve the diagnostic accuracy and the level of
diagnosis on HAVD in China, we performed high frequency ultrasound in patients with HAVD,
and analyze the ultrasonic characteristics of the median nerve and transverse carpal ligament.
Methods
We collected data from 15 patients (30 wrists) who were treated in our hospital from May
2014 to August 2015, all were male, aged between 25 to 45 years old with average age of 34.8
years old. They were exposed to HTV for 5 to 17 years, with average working years of 9.7 years.
They all met Diagnosis of occupational hand-arm vibration disease diagnostic criteria (GBZ7-
2002). All the patients worked on the grinding operation for golf products manufacturing
enterprises. Their occupational history was clear. All patients had different degrees of hand
peripheral circulation and (or) arm neurological dysfunction symptoms and signs. The main
symptoms were hand bilges, numbness, weakness, sweating, etc. Cold-water restored temperature
test showed: the restored temperature time was prolonged. EMG showed different degrees of
abnormality. Patients with the primary Raynaud's syndrome, peripheral vascular obstruction as
well as lead, mercury and other occupation poisoning history were excluded. At the same time, 20
healthy volunteers (40 wrists) were selected as the control group, and all were male, aged between
27 to 44 years old with an average of 35.7 years. We used color Doppler ultrasonic diagnostic
apparatus (GE E9 LOGIQ). Probe frequency was 6-15MHZ, initial set to muscle test conditions.
We used SPSS 17 statistical software for statistical analysis. The measurement data were expressed
by means of mean±SD. The mean was compared by t-test and the significance level was set to
0.05.
Results
The transverse carpal ligament of 15 patients (30 wrists) with HAVD and 20 cases (40
wrists) of the control group showed a strong hyperechoic and separated in the meantime hypoecho
band. The median nerve transection in the two groups was round, oval and low echo area.
Longitudinal section showed parallel, streaky and low echo area. 15 cases (30 wrists) with HAVD
were not detected inhomogeneous echo enhancement of the carpal transverse ligament, median
nerve swelling, and the echo blurred. There was no obvious difference in the morphology and the
105
echo of the two groups.
In 15 cases (30 wrists) with HAVD, the patients' carpal transverse ligament thickness at
the hook of the hamate bone was (0.33±0.05) cm, the median nerve diameter was (0.22±0.02) cm.
Compared with the control group separately, the differences were not statistically significant
(p>0.05).
15 cases (30 wrists) with HAVD who were (0.08±0.02) cm2 compared with the control
group who were (0.10±0.01) cm2 in the median nerve area at the hook of the hamate and pisiform
bone, the difference was not statistically significant (p>0.05).
Discussion
Cold-water restored temperature test and the electro-physiological examination cannot
directly reflect the adjacent relationship and provide the morphological changes caused by nerve
compression. But clinicians also want to understand the relationship between peripheral nerve and
blood vessels, so it is becoming more and more important for the study of imaging diagnosis. At
present, although X-ray, magnetic resonance imaging and so on can be displayed directly, yet it is
time consuming and expensive. However, as a traditional diagnostic method, ultrasonagraphy is
widely used in clinical practice because of its advantages, such as real-time, direct, noninvasive,
low price and so on. With the development of ultrasonic technology, the resolution of high
frequency ultrasound has reached 400μm, and it can clearly show the nerve tissue around it. And
compared with magnetic resonance imaging, it is easier to observe the real-time activity of nerve
and tendon. The anatomy of the median nerve is always in contact with the transverse carpal
ligament, which is especially helpful to the recognition of ultrasonic images.
In the research of HAVD with X-ray and magnetic resonance imaging, in addition to the
display of patients with wrist joint bone sclerosis, osteoporosis, and wrist joint necrosis, magnetic
resonance imaging also shows the damage of the joint fluid and soft tissue. In the application of
ultrasonagraphy in this group: 15 cases (30 wrists) with HAVD were not detected inhomogeneous
echo enhancement of the transverse carpal ligament, median nerve swelling, and the echo blurred.
There was no significant difference in the morphology and echo between the two groups. No
obvious effusion and soft tissue injury were found in the joint cavity. This study has not yet
indicated that the arm vibration may cause damage to the wrist and middle nerve, but the cause of
the arm vibration disease is more complicated. Whether or not it will cause damage to the wrist of
the patient needs further research.
In some study, patients with HAVD mainly showed the prolongation of the distal motor
latency of median nerve and ulnar nerve. In this study, 15 cases (30 wrists) with HAVD and the
control group (20 cases, 40 wrists) shows no statistical significance in comparison of transverse
carpal ligament thickness at the hook of hamate bone and median nerve diameter. Combined with
the related research, HAVD may have a functional effect on the patient's median nerve. But the
effect on the morphology of the median nerve and the transverse carpal ligament was not obvious.
But there are few data collected at present, and the influence of the median nerve and transverse
carpal ligaments in the patients still need to be further explored.
Ultrasound examination can be clear to show the contents of carpal tunnel imaging changes
by combination of static and dynamic display, observe its morphology and echo performance,
particularly, measure the thickness and the inner diameter of the median nerve, and quantify the
cross-sectional area of the wrist. So we suggest that this can be used as a new diagnostic criteria
for clinical diagnosis of HAVD to provide an objective and scientific basis for diagnosis.
106
THE EFFECITVENESS OF NAILFOLD CAPILLAROSCOPY IN THE DIAGNOSIS OF
HAND-ARM VIBRATION SYNDROME AMONG GOLD MINERS
Guiping Chen+, Bin Xiao+, Maogong Shi++, Danying Zhang+, Fansong Zeng+, Bei Yang++,
Hansheng Lin+, Xuqin Cao+, *Qingsong Chen+
+Guangdong Province Hospital for Occupational Disease Prevention and Treatment; and
Guangdong Provincial Key Laboratory of Occupational Disease Prevention and Treatment,
Guangzhou, Guangdong 510300, China ++Occupational Disease Hospital of Yantai City, Shandong 264000, China
*Correspondence to: [email protected]
Introduction
Hand-held vibrating tools operated by workers over a long period of time can lead to the
development of hand-arm vibration syndrome (HAVS)1. Among the symptoms of the syndrome,
vibration-induced white finger (VWF) is the most typical. Capillaroscopy is extensively utilized
in the clinical diagnosis of Raynaud’s syndrome, but it is relatively less frequently used in the
diagnosis of HAVS. The purpose of this study was to investigate the effectiveness of
nailfoldcapillaroscopy on the diagnosis of HAVS.
Methods
A total of 114 male gold miners were recruited, 35 with HAVS, 39 without HAVS as vibration-
exposed controls (VEC), and 40 as non-vibration-exposed controls(NVEC). Video of
capillaroscopy was used to capture images of the 2nd,3rd, and 4th fingers of both hands of all subjects
at heart level after 10 minutes of rest at a room temperature of 20°C. The number of capillaries/mm,
avascular areas, microhemorrahages, and enlarged capillaries were evaluated under blinded
conditions2,3. The effectiveness of nailfoldcapillaroscopy on the diagnosis of HAVS was
systematically assessed by statistical differences in morphological criteria among the groups as
well as sensitivity and specificity according to ROC curve analysis.
Results and Discussions
Significant differences in morphological criteria (avascular areas, microhemorrhages, and
enlarged capillaries, Figure1) existed between the groups (P<0.05; Table 1). Avascularareas in
HAVS, VEC, and NVEC appeared in 74.3%, 43.6%, and 25.0%of subjects, respectively. A higher
percentage of subjects had microhemorrhages in the HAVS group (65.7%) compared with the other
groups (VEC: 7.7% and NVEC: 7.5%). As shown in Figure 2, the number of capillaries/mm ROC
Curve(95%CI) had cut-off value 8.25 capillaries/mm, sensitivity 68.6% and specificity 79.5%,
with an area of 0.780(0.684, 0.877, P<0.001).
Nailfold capillary damage in gold miners was more severe in HAVS patients than in VEC and
NVEC subjects. This suggested that nailfold microcirculation morphological criteria (ie, the
number of capillaries/mm, avascular areas, microhemorrahages, and enlarged capillaries) had high
value in the diagnosis of HAVS.
107
(a) Avascular area (b)Microhemorrhage (c)Enlarged capillary
Figure1.Variations of abnormal nailfold capillaries
Table1: Morphological criteria
HAVS(n=35) VEC(n=39) NVEC(n=40) P
Microhemorrhages,n(%) 23(65.7)a,c 3(7.7) 3(7.5) <0.001
Enlarged capillaries,n(%) 21(60.0)c 10(25.6)b 10(25.0) 0.04
Avascularareas,n (%) 26(74.3)c 17(43.6) b 10(25.0) <0.001
Number of capillaries/mm,mean±SD 7.41±1.79a,c 8.87±1.80b 9.69±1.22 <0.001 aHAVS vs. VEC:P<0.05;bVEC vs. NVEC:P<0.05;cHAVS vs. NVEC:P<0.05.
(a) Number of capillaries/mm boxplot(b) Number of capillaries/mm ROC Curve
Figure 2: Number of capillaries/mm boxplot and ROC Curve
References
1. Busi Nayantumbu, Chris M. Barber, Mary Ross et al. (2007). Hand-arm vibration syndrome in South
African gold miners. Occupational Medicine 57: 25-29.
2. MaurizionCutolo, Carmen Pizzorni, Alberto Suli (2005). Capillaroscopy. Best Practice & Research
Clinical Rheumatology 19(3): 437-452.
3. Francesca Ingegnoli, Roberta Gualtierotti, Chiara Lubatti et al. (2013). Nailfold capillary patterns in
healthy subjects: A real issue in capillaroscopy. Microvascular Research 90: 90-95.
108
Session IX: Prevention, Intervention, and Training
Chairs: Paul-Émile Boileau and Qingsong Chen
Presenter Title and authors Page
Hans Lindell Zero vibration injuries – a Swedish holistic approach
fighting vibration injuries
Hans Lindell
109
Alice Turcot The engineer and the physician: can they understand each
other when they talk about machine vibration?
Alice Turcot, Marie Fortier
111
Mallorie Leduc Building awareness: hand arm vibration syndrome
training and education in the construction industry
Mallorie Leduc, Ron House, and Tammy Eger
113
Karim Hamouda Performance evaluation of vibration-reducing gloves at
the fingers using finger adapter
Karim Hamouda, Pierre Marcotte, Subhash Rakheja
115
109
ZERO VIBRATION INJURIES – A SWEDISH HOLISTIC APPROACH FIGHTING
VIBRATION INJURIES
Hans Lindell
Swerea IVF, Box 104, 431 22, Mölndal, Sweden
Introduction
Vibration injuries constitute the second most common cause of occupational injuries
among males in Sweden and the incidence among women is steadily increasing1. In the current
situation several industry sectors do not comply with EU directives2,3 for vibration exposure often
due to no availability of machines with low vibration levels. Also in areas where there are effective
technical solutions, lack of knowledge is an important factor leading to constant or increasing
vibration injury. The problem is complex and needs a broad co-operation in the society in order to
be solved. The machine producers don’t experience that there is a demand for low vibration
machines and have difficulties to find robust technical solutions, and the machine users on the
other hand often have difficulties to find low vibrating alternatives. The occupational medicine
cannot cure the injuries. The Swedish work environment authority, employer and labor
organizations also have difficulties to effectively address the problem. The economic cost of
vibration injury is significant in Sweden. According to Swedish Parliament Research Service4 the
total health insurance expenditure for all diagnoses that can be associated with vibrations in 2009
is estimated to about 7 billion SEK annually.
However the project “Zero Vibration Injuries” is a Swedish initiative with the objective to
take a holistic approach on the problem. It is starting in June 2015 and will end in August 2017
and is financed by the Swedish Innovation Agency, Vinnova. The project is holistic in the sense
that the consortium involves all stakeholders in the society, i.e. machine manufacturers, a
comprehensive range of machine users, the Swedish work environment authority, employer and
labor organizations together with occupational medicine and vibration researchers. The consortium
will have a great potential to set requirements on vibrating machines and bring about change in
society.
The strategy is to develop low vibration concept prototypes representing main problem
areas which will then form the basis for specifying requirements on manufacturers from the user
side. The project will demonstrate that machines do not need to vibrate and injure people. The
development of low vibration machines will be based on newly developed technology with
Nonlinear Tuned Vibration Absorbers5 for machines with a reciprocating action and Automatic
Balancing6 for those with rotating vibrations. Also the high frequency content of vibrations above
1250 Hz, that ISO 5349 does not include, will be reduced since it is believed to cause substantial
vibration damage.
EU has a comprehensive regulatory framework from 2005 to deal with vibration injuries.
This constitutes the Vibration Directive stipulating maximum vibration dose and requirements for
health checks but also by the Machine Directive. The Machine Directive provides that machine
manufacturers are obligated to make use of state-of-the-art technology for vibration reduction and
declare how much the machines vibrate. The problem of vibration injuries is not about a lack of
regulation but primarily of non-compliance, which in turn is largely due to lack of low vibration
110
machine alternatives and legal enforcement from authorities. An excellent summary of the current
situation and history behind is made by P. Donati7.
Methods
The project has two main approaches to address the vibration problem.
The first approach is to develop representative conceptual machines with a hand-arm
weighted vibrations target level below 2.5 m/s2 and with reduced high frequency content,
i.e. >1250 Hz. This is accomplished by using newly developed technology for reciprocating
machines and automatic balancing for rotating machines together with traditional vibration
reduction approaches.
The second approach is to take precautions against high frequency transient impact
vibration. There are numerous findings8-11 that indicate that the acceleration weighting curve in
ISO 5349 is not sufficient to cover effects from high frequency and transient vibrations which is
also stated in the standard itself. Reducing high frequency vibrations is from a technical
perspective generally much easier than at lower frequencies but today there is no incentive for
machine manufacturers since there is no standard to measure it. Hopefully will this change in the
near future. The conceptual machines will have a low level of high frequency vibrations, i.e
frequencies above 1250 Hz.
The low vibration conceptual machines will after completion form the basis for
specification requirements from the machine user industry and will in turn both push and give
incentive for the machine producer industry to adopt new technology and develop machines that
do not injure the operator. In this way the project hopes to make a substantial contribution to a
society where occupational injuries by vibrating machines are less frequent.
References
1. AFA Försäkring Arbetsskaderapport 2014, In Swedish.
2. EU Machine Directive (1989/392/EC)
3. EU Vibration Directive (2002/44/CE)
4. Riksdagens Utrednings Tjänst, Arbetsmiljöfrågor – Vibrationer, Dnr:2012:822
5. Lindell H. Patent WO 2014/095936 A1
6. Lindell H, (1996) “Vibration reduction on hand-held grinders by automatic balancing”, Central European journal
of public health 4, No 1, 43-45
7. Donati P. “Joël’s Breaker: Forty Years of European Vibration Prevention” Industrial Health 2012, 50, 370–376
8. Barregård L. et al. Investigation of car repair shop workers in Gothenburg - Report 1 & 2, (1992)
9. Lindell H, Lönnroth I, Ottertun H. (1998) Transient vibration from impact wrenches: Vibration negative effect
on blood cells and standards for measurement, Eighth International Conference on Hand-Arm Vibration, Umeå,
Sweden, June 9-12, 113-117
10. Hideo Ando et al. Effect of impulsive vibration on red blood cells in vitro, Scand J Work Environ Health
2005;31(4):286-90.
11. Govinda Raju, S. et al. Vibration from a riveting hammer causes severe nerve damage in the rat tail model,
Muscle&Nerve, Volume 44, Issue 5, p. 795–804, 2011
Acknowledgements
This project was funded by AFA Insurance and the Swedish Innovation Agency VINNOVA.
111
THE ENGINEER AND THE PHYSICIAN: CAN THEY UNDERSTAND EACH OTHER
WHEN THEY TALK ABOUT MACHINE VIBRATION?
*Alice Turcot, Marie Fortier
Institut national de santé publique du Québec, Québec, CANADA
Introduction
Hand-arm vibration syndrome (HAVS) is a disease related to exposure to the vibrations generated by
vibrating tools. In Québec, it is estimated that 400,000 workers are exposed to hand-arm vibration from grinders,
concrete breakers, orbital sanders, pneumatic wrenches, chain saws, jack hammers, etc.1 However, the number of
workers exposed to whole-body vibration (WBV) is not known.
HAVS consists of three distinct types of diseases, namely vascular disease, neurologic disease and
musculoskeletal disease. These three types of diseases can evolve simultaneously or separately and threaten the quality
of life of the workers affected. We are dealing with a complex disease whose pathophysiological mechanisms are still
not completely understood. Risk evaluation by measuring the acceleration of the vibrations requires training in
measurement itself and specific knowledge in order to properly evaluate the factors that could limit the analysis, such
as working postures, the presence of impacts, the gripping and thrusting strength, etc. In fact, the biodynamic
behaviour of the hand-arm system subjected to vibration is complex. All of the parameters that come into play in risk
evaluation still have to be mastered. Different modalities developed by engineers allow biodynamic behaviour to be
studied, including modeling. The same is true for the study of WBV relating to risk assessment and risk prevention
measures, the health effects that must be better described, and the modeling that allows a better understanding of the
behaviour of the whole body subjected to vibration.
Study of HAVS and the diseases linked to WBV therefore requires knowledge belonging to at least two
different disciplines, namely medicine and engineering. Does a common language base exist as well as a desire to
implement interdisciplinary action between physicians and engineers? Can these experts understand each other? The
goal of the present study is to document whether a common base of exchanges exists between these two disciplines,
and to document the obstacles or issues, to allow interdisciplinary practice and to ensure an effective transfer of
knowledge between the two disciplines.
Methods
To answer these questions, we analyzed the university curriculum in Québec in the fields of medicine and
engineering, specifically the types of courses planned in the undergraduate, master's and doctoral programs that
address occupational health and safety in these respective disciplines. Subsequently, we identified the number of
scientific presentations that refer to an interdisciplinary study in the context of international and American conferences
since 2001 dealing with hand-arm vibration or WBV. Finally, using a semi-structured questionnaire, we proceeded to
analyze the content of interviews conducted with physicians (n=5) and engineers (n=5), representing academia and
having worked directly or indirectly on the prevention of vibration. The duration of the interviews varied from 1.5
hours to two hours.
Results and Discussion
The study revealed a certain number of obstacles and barriers in interdisciplinary collaboration. In particular,
regarding the university curriculum of these two disciplines, the diversity and abundance of knowledge on both sides
do not allow sufficient attention to be paid to the issue of vibration in occupational health. However, two studies show
that the interdisciplinary collaboration introduced in university training is providing winning results for future
physicians when medical disciplines that already share a common language are involved.2,3 The situation is very
different with engineering and medicine because they do not have a common knowledge perspective. Analysis of the
academic curriculum, for physicians as well as engineers, reveals that risk measurement, knowledge of the health
effects, and the understanding of preventive measures are fragmentary.
Between 2001 and 2014, 14 American or international conferences dealt with hand-arm or whole-body
vibration. However, based on the retrieval of topics in conference proceedings, interdisciplinary collaboration remains
112
fragmentary and limited. Research on the biomechanical aspects of vibration, on preventive measures, and on the
medical and diagnostic aspects of disease, remains active without being networked in Canada.
While preliminary, this study also identified major obstacles in physician-engineer collaboration in the field.
These obstacles relate to the complexity of the risk and to all of the technical parameters that must be taken into
account in measurement; the unfamiliarity with measurement methods for engineers as well as physicians; the difficult
updating of knowledge about vibration in the vast field of occupational health priorities; the versatility of occupational
health physicians, limiting their specialization with respect to vibration; the lack of a culture of exchanges regarding
the solving of problems in the field of vibration; the lack of recognition of vibration as a priority health problem; and
research funding determined by "popular" topics where vibration is not included, etc. The results of a prior study on
risk perception had already shown the lack of awareness of risk, by physicians, workers, and employers.4 A survey in
United States has shown that a large portion of the surveyed American Society of Safety Engineers safety and health
members haven’t heard of WBV, suggesting enhanced efforts by governmental, professional, and educational
organizations to increase WBV topic knowledge among safety and health practitioners.5 As a result, it is not surprising
to note that interdisciplinary collaboration is problematic. To make up for this lack of a common language between
the two disciplines, it would be beneficial to establish a community of practice, in order to create a common space for
exchanges between the experts from the different disciplines, including clinicians.
Furthermore, the present study shows that efforts must be made in the transfer of knowledge. This could be
achieved by stages determined in the literature.6 Also, research topics such as the characterization of vibration
exposure in mining vehicles; or even measurement of the vibration emitted from different tools, under simulated
laboratory conditions; the contribution of factors such as gripping strength to the transmissibility of the vibration to
the hand-arm system; the measurement of vibration according to different ISO standards; the understanding of the
variation in sensitivity of the human body, based on the different frequencies of the vibration spectrum, based on the
measurement axis, or even according to the hand-seat-foot location; modeling; the analysis of the dynamic response
of a finger exposed to vibration by using finite element models, are many examples of topics involving a language
belonging to engineers, difficult for occupational physicians in the field to adopt, and requiring particular attention to
the factors promoting the transfer of knowledge at all stages in the process.
The challenges of occupational physicians and engineers do not seem to dovetail. More specific ergonomic
knowledge in the university curricula of both disciplines could possibly be the beginning of a common basis for the
work of engineers and occupational physicians.
References
1. Martin, R. et al. (2004). Estimation du nombre de travailleurs québécois exposés à des vibrations au-delà du
seuil d’intervention, Agence de santé et des services sociaux de Chaudière-Appalaches, Direction de la santé
publique, Sainte-Marie de Beauce, Québec, Canada.
2. Nørgaard, B., Draborg, E., Vestergaard, E., Odgaard, E., Jensen, D.C., and Sørensen, J. (2013). Interprofessional
clinical training improves self-efficacy of health care students. Medical Teacher 35(6): e1235-e1242.
3. Hallin, K., Kiessling, A., Waldner, A., and Henriksson, P. (2009). Active interprofessional education in a patient
based setting increases perceived collaborative and professional competence. Medical Teacher 31(2): 151-157.
4. Tessier, B., and Turcot, A. (2012). Perceptions à l’égard des risques reliés à l’utilisation des outils vibrants en
milieu de travail. Agence de la santé et des services sociaux de Chaudière-Appalaches, Direction de santé
publique, Sainte-Marie de Beauce, Québec, Canada.
5. Paschold, H.W. (2008). Survey of whole-body vibration awareness and knowledge among safety and health
professionals in the United States. 2nd American Conference on Human Vibration, Proceedings, June 4-6, pp. 81-
82.
6. Lemire, N., Souffez, K., and Laurendeau, M.C. (2009). Animer un processus de transfert des connaissances, Bilan
des connaissances et outil d’animation. Institut national de santé publique du Québec, Direction de la recherche
et développement, Québec, Canada, No publication 1012, p. 13.
113
BUILDING AWARENESS: HAND ARM VIBRATION SYNDROME TRAINING AND
EDUCATION IN THE CONSTRUCTION INDUSTRY
*Mallorie Leduc+, Ron House++, and Tammy Eger+
+Centre for Research in Occupational Safety and Health, Laurentian University,
Sudbury, ON, Canada, ++University of Toronto & St. Michael’s Hospital, Toronto, ON, Canada,
Introduction
Exposure to hand operated vibrating tools within the construction industry places workers
at risk for developing hand-arm vibration syndrome (HAVS). Damage to the vascular,
neurological, and musculoskeletal systems of the hand and arm is typically progressive with
continued vibration exposure and often irreversible. As such, prevention efforts are imperative for
the management of HAVS. The use of anti-vibration (AV) gloves is often recommended as
personal protective equipment while operating vibrating tools. In Ontario, Canada, it is the duty of
an employer to “provide information, instruction and supervision to a worker to protect the health
or safety of the worker.”1 In 2014, basic worker health and safety awareness training was made
mandatory for all workers in Ontario. The training outlines the duties of the workers, supervisors,
and employers according to the Occupational Health and Safety Act, common workplace hazards,
participation in joint health and safety committees, and additional resources within Ontario’s
workplace health and safety system. Furthermore, fall protection training for workers working at
heights and Workplace Hazardous Materials Information System (WHMIS) training for the safe
use, storage and removal of chemicals and hazardous materials in the workplace is mandatory
within the industry. However, without education focused specifically on prevention and reduction
strategies of HAVS in the construction industry, a continued lack of awareness and under-
recognition of the common occupational disease will persist. The purpose of the study was
twofold: (1) to outline health and safety training obtained by construction workers, and (2) to assess
which factors influence AV glove utilization of construction workers following an educational
intervention and occupational health clinic assessment for HAVS.
Methods
100 workers from the construction industry referred for an assessment of HAVS at a
hospital-based out patient occupational health clinic in Toronto, Ontario, Canada were recruited.
A baseline questionnaire was given to all participants at their assessment, which documented their
prior health and safety training opportunities and AV glove utilization. A HAVS education
resource, a one page double-sided laminated document, was given to all participants. Participants
were given three copies and were asked to distribute at their respective workplace. Two months
following the assessment and educational intervention, a follow up questionnaire was mailed to all
participants. The training results were analyzed using descriptive statistics and a stepwise logistic
regression was used to assess the predictors of AV glove utilization following the educational
intervention and assessment.
114
Results and Discussions
Almost all of the participants indicated they had completed health and safety training
within their workplace (90% Occupational Health and Safety Act, 96% WHMIS, 85% general
health and safety training). In contrast, only 5% received HAVS training while 49% indicated they
received some form of other training regarding the use of protective gloves. However, only 8%
received training on AV gloves in particular. Only 4.1% of the participants reported wearing AV
gloves when exposed to hand-arm vibration at baseline.
57 participants completed the follow-up questionnaire. Following assessment at the
occupational health clinic and receiving the educational intervention, 42.9% indicated to have
increased their use of AV gloves. Associated with increased AV glove use was participants sharing
of the educational information with their employers, supervisors and health and safety
representatives. A logistic regression was performed to ascertain the effects of information sharing
on the likelihood of participants increasing AV glove use. The logistic regression model was
statistically significant, χ2(1) = 13.349, p < .001. The model explained 34.3% (Nagelkerke R2) of
the variance in AV glove use and correctly classified 75.6% of the cases. Only one predictor
variable was statistically significant: sharing the information with their employer. Participants who
share the educational information with their employer had 14.67 times higher odds to increase AV
glove use than those who did not share the educational information with their employer.
The current health and safety training opportunities within the construction industry are
not adequately preventing and protecting workers from HAVS. Training opportunities targeted
specifically on education and the prevention of HAVS are rarely being offered to workers. The
educational intervention proved most effective in increasing AV glove use when the information
was shared within the workplace, especially with the participant’s employer. Therefore, the
employer is an important component in leading positive behavior change of their employees.
HAVS focused education may be a missing and integral role in the prevention and recognition of
HAVS within the workplace. Increasing the knowledge of workers may improve their ability to
seek appropriate medical treatment and begin dialogue with physicians’ related to the origin of
their symptoms and may indirectly influence the reporting of occupational diseases2. Furthermore,
the purchasing of tools with lower vibration emission values, process changes, reduction in
employee exposure duration, and provision of additional education opportunities regarding HAVS
were also important control changes made by the employer that occurred at many worksites as a
result of the educational intervention3. Creating dialogue and increasing awareness and education
of HAVS within the workplace at both the worker and employer level should be considered
moving forward.
References
1. Occupational Health and Safety Act, RSO (1990). C 0.1, Section 25(2)(a).
2. Curti, S., Sauni, R., Spreeuwers, D., De Schryver, A., Valenty, M., Riviere, S., Mattioli, S. (2015).
Interventions to increase the reporting of occupational diseases by physicians. Cochrane Database of
Systematic Reviews. Issue 3. Art No.: CD010305.DOI:10.1002/14651858.CD010305.pub2.
3. Thompson, A.M.S., House, R., Holness, D.L. (2012). Education of employers and employees on
effective prevention of hand-arm vibration syndrome: results of an innovation grant study.
Proceedings from the 4th American Conference on Human Vibration. June 13-15th, 2012. Hartford,
USA.
115
PERFORMANCE EVALUATION OF VIBRATION REDUCING GLOVES AT THE
FINGERS USING FINGER ADAPTER
*Karim Hamouda+, Pierre Marcotte++, Subhash Rakheja+
+Concave Research Centre, Concordia University, Montreal, QC, Canada ++IRSST, Montreal, QC, Canada
Introduction
Vibration-reducing (VR) gloves are widely used in many industries to protect workers from
exposure to vibration transmitted by hand-held power tools. Effectiveness of different VR gloves
in reducing hand-transmitted vibration (HTV) has been extensively investigated through
measurements at the palm using standardized palm-adapter1. Vibration transmission properties of
VR gloves to the fingers, however, have been addressed in only a few studies2. Moreover, the
standardized procedure for assessing vibration attenuation performance of VR gloves requires
measurement of vibration transmission at the palm only, assuming similar vibration transmission
to the fingers. The reported studies, however, have shown substantial differences between the
palm- and finger-vibration transmissibility characteristics2. In this study, a finger adapter is
designed to measure finger vibration transmission properties of different VR gloves, in addition to
the palm vibration transmission using the standardized palm adapter.
Methods
Palm-and finger vibration transmission of 12 different
VR gloves were measured in the laboratory with 12
subjects. Measurements were performed on an
instrumented handle, capable of monitoring hand-grip
and push forces, mounted on a vibration exciter, as
described in ISO 108191. Test gloves included air, gel,
gel-foam, hybrid and leather. The standardized palm
adapter, containing a miniature three-axis accelerometer,
was used to measure vibration at the palm. A reported
study has observed peak fingers vibration near middle
phalanges of index and middle fingers. Two Velcro finger
vibration adapters, each containing a miniature three-axis
accelerometer, were thus designed to measure vibration
near mid-phalanges of index and middle fingers. Each
glove was cut near these locations so as to tightly secure
finger adapters on the gloved hand of each subject, as
shown in Fig. 1. Repeatability and reproducibility of
measurements were thorough evaluated through repeated
measurements under a band-limited random vibration in the 25 to 1600 Hz range, as defined in
ISO 108191. Palm and finger vibration responses of gloves were subsequently acquired for each
subject, while subject grasped the handle with 30 N grip and 50 N push force. Each measurement
was repeated twice and data were analyzed to obtain palm as well as fingers vibration
transmissibility characteristics of the VR gloves.
Fig. 1: Gloved hand with fingers
adapters
Fig. 1: Gloved hand with fingers
adapters
116
Results and Discussions
Figure 2 shows the palm and fingers vibration transmissibility characteristics of 12 gloves,
averaged over the 12 subjects. Figure also shows mean transmissibility measured with bare hand (BH) of
the subjects. The finger responses of VR gloves are presented for both the middle- and index-fingers. The
overall vibration isolation effectiveness of each glove was evaluated from the frequency-weighted rms
accelerations using the total effective acceleration transmissibility (TEAT) method3. Identical weighting
was used for both the palm and the fingers vibration. Table 1 summarizes overall vibration transmission to
the palm and fingers with different gloves used in the study. While the air gloves are considered as VR
gloves according to ISO 108191, the index and middle fingers’ transmissibility characteristics show
vibration amplification in mid-frequency range and only limited attenuation in high-frequency range.
Fig. 2: Bare and gloved hand; 1/3 octave band frequency response for (a) palm, (b) index and (c) middle fingers.
Table 1: Weighted M- and H- vibration transmissibility of gloves measured at the palm and fingers.
Palm Index Middle
Glove M -
Spectrum
H -
Spectrum
M -
Spectrum
H -
Spectrum
M -
Spectrum
H -
Spectrum
Air 1 0.81 0.59 1.30 0.96 1.24 0.92
Air 2 0.81 0.65 1.83 0.75 1.38 0.91
Air 3 0.79 0.63 1.74 0.80 1.28 0.89
Gel 1 0.95 1.02 1.84 1.08 1.29 1.21
Gel 2 0.82 0.55 1.90 0.50 1.53 0.78
Gel 3 0.87 0.82 1.73 0.80 1.29 0.91
Foam Gel 1 0.94 1.02 1.80 1.09 1.26 1.22
Foam Gel 2 0.89 0.81 1.77 1.01 1.33 0.98
Hybrid 1 0.77 0.57 1.71 0.93 1.21 1.11
Hybrid 2 0.80 0.63 1.74 0.92 1.23 1.11
Hybrid 3 0.79 0.61 1.73 0.91 1.21 1.07
Leather 0.95 1.05 1.78 1.39 1.24 1.22
References
1. ISO 10819 (2013). Mechanical Vibration and Shock - Method for the Measurement and Evaluation of the
Vibration Transmissibility of Gloves at the Palm of the Hand, Geneva, Switzerland.
2. Welcome, D.E., Dong, R.G., Xu, X.S., Warren, C. & McDowell, T.W. (2014). The effects of vibration-reducing
gloves on finger vibration. Int.J.Ind.Ergonomics 44: 45-59.
3. Dong, R., Rakheja, S., Smutz, W., Schopper, A., Welcome, D. & Wu, J. (2002). Effectiveness of a new method
(TEAT) to assess vibration transmissibility of gloves. Int.J.Ind.Ergonomics 30: 33-48.
117
Index of Authors
Almagirby Almaky 62 Grétarsson Snævar
Leó 42
Bain James 7 Griffin Michael J. 22
Berbyuk Viktor 42 Gunnarsson Lars-
Gunnar 95
Bochmann Frank 93 Hagberg Mats 16
Boileau Paul-Émile 73 Hamouda Karim 115
Botti Teresa 60,84 Harada Noriaki 14
Brammer Anthony J. 12,91,102 Hase Ryosuke 14
Bruchmueller Tim 75 He Lihua 9,99,104
Bryngelsson Ing-Liss 95 Holness L 18
Burström Lage 3 Hossain Mahbub 14
Byrnell Heather 36 House Ron 18,82,113
Cao Xuqing 5,24 Hua Yue 67
Cao Xuqin 106 Huang Hanlin 49
Carré Matt J. 62 Inclima Rick 38
Cerini L. 84 Ishitake Tatsuya 14
Chen Guiping 5,24,47,51,106 Johanning Eckardt 38
Chen Qingsong 5,24,47,49,51,106 Josefsson Mattias 42
Cherniack Martin G. 102 Kalra M. 33
Dewangan Krishna 33 Kaulbars Uwe 29,93
Dickey James P. 36 Kawano Yoshinao 14
Dong Ren G. 27,44,54,56,69 Kuczynski Jacek 97
Eckert Winfried 93 Kurozawa Youichi 14
Eger Tammy 36,82,113 Landsbergis Paul 38
Fattorini L. 88 Lang Li 5,24,49,51
Fortier Marie 111 Leduc Mallorie 82,113
Ganghoffer Jean-François 67 Lemerle Pierre 67
Gerhardsson Lars 16 Li Zhimin 104
Germann René 79 Li Hongling 51
Gillstrom Lennart 16 Lin Hansheng 5,24,47,49,106
Giovanni Raoul Di 60,84,88 Lindell Hans 42,109
Godwin Alison 36 Lindgren Bernt 95
Goggins Katie 82 Liu Yanzhi 104
Gong Manman 9,99 Lu Qiongjie 104
Graff Pål 95 Lunghi Alessandro 60,84,88
118
Mangold Sebastian 75,77,79 Toibana Norikuni 14
Marchetti Enrico 60,84,88 Truenkle Bernhard 75
Marcotte Pierre 33,115 Turcot Alice 86,111
Matthiesen Sven 75,77,79 Vihlborg Per 95
McDowell Thomas W. 44,54,56,69 Wahlström Jens 3
McKay Siobhan C. 20 Wang Shu 73
Moleti A. 84 Wang Rugang 9,99
Nilsson Tohr 3 Wang Sheng 9,99
Noël Christophe 58,71 Warren Christopher 27,44,54,56
Persson Magnus 7 Welcome Daniel E. 27,44,54,56,69
Pitts Paul 91 Wu John Z. 54,56,69
Rakheja Subhash 33,73,115 Xiao Bin 5,24,47,49,51,106
Rempel David 31 Xie Lan 64
Riley Danny 7 Xu Xiangrong 9,99,104
Rongong Jem A. 62 Xu Xueyan S. 44,54,56
Ruel-Laliberté Jessica 86 Xu Guoyong 24,47
Sacco Floriana 60,84,88 Yan Maosheng 51
Saggin Bortolino 40,64 Yan Hua 5,47
Sanjust Filippo 60,84 Yan Maosheng 5,47
Scaccabarozzi Diego 40,64 Yang Aichu 5,24,49
Schäfer Tobias 77 Yang Bei 106
Schmidt Sebastian 77 Ye Ying 22
Shi Maogong 106 Yu Gongqiang 102
Shiralkar Sandy P. 20 Yuan Zhiwei 9,99
Sinsel Erik W. 27 Zeng Fansong 5,49,51,106
Sisto Renata 60,84 Zhang Danying 24,51,106
Stelzer Daniel 75 Zimmerman Jordan 7
Sun Yi 93
Takahashi Tsunehiko 14
Tang Shichuan 47,49
Tarabini Marco 40,64
Taraschuk I 18
Thompson Aaron 82
Tirabasso Angelo 60,84,88