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Occupational Medicine Advance Access originally published online on August 23, 2006
Occupational Medicine 2007 57(1):25-29; doi:10.1093/occmed/kql089
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C. Barber, Health and Safety Laboratory. © Crown Copyright 2006. Reproduced with the permission of the Controller of Her Majesty's Stationery Office.

Hand–arm vibration syndrome in South African gold miners

Busi Nyantumbu1,2, Chris M. Barber3, Mary Ross1,2, Andrew D. Curran3, David Fishwick3, Belinda Dias2,4, Spo Kgalamono1,2 and James I. Phillips1

1 National Institute for Occupational Health, Johannesburg, South Africa
2 School of Public Health, The University of the Witwatersrand, Johannesburg, South Africa
3 Centre for Workplace Health, Health and Safety Laboratory, Buxton, UK
4 Council for Scientific and Industrial Research, South Africa

Correspondence to: Chris Barber, Centre for Workplace Health, Health and Safety Laboratory, Harpur Hill, Buxton, Derbyshire SK17 9JN, UK. Tel: +44 1298 218169; fax: +44 1298 218471; e-mail: chris.barber{at}hsl.gov.uk


   Abstract
Top
 Abstract
Introduction
 Methods
 Results
 Discussion
 Conflicts of interest
 References
 
Background Hand–arm vibration syndrome (HAVS) is associated with the use of hand-held vibrating tools. Affected workers may experience symptoms of tingling, numbness, loss of grip strength and pain. Loss of dexterity may impair everyday activities, and potentially increase the risk of occupational accidents. Although high vibration levels (up to 31 m/s2) have been measured in association with rock drills, HAVS has not been scientifically evaluated in the South African mining industry.

Aims The aim of this study was to determine the prevalence and severity of HAVS in South African gold miners, and to identify the tools responsible.

Methods A cross-sectional study was conducted in a single South African gold-mine. Participants were randomly selected from mineworkers returning from annual leave, comprising 156 subjects with occupational exposure to vibration, and 140 workers with no exposure. Miners who consented to participate underwent a clinical HAVS assessment following the UK Health and Safety Laboratory protocol.

Results The prevalence of HAVS in vibration-exposed gold miners was 15%, with a mean latent period of 5.6 years. Among the non-exposed comparison group, 5% had signs and symptoms indistinguishable from HAVS. This difference was statistically significant (P < 0.05). All the cases of HAVS gave a history of exposure to rock drills.

Conclusions The study has diagnosed the first cases of HAVS in the South African mining industry. The prevalence of HAVS was lower than expected, and possible explanations for this may include a survivor population, and lack of vascular symptom reporting due to warm-ambient temperatures.

Keywords      Hand–arm vibration syndrome; South Africa; vibration exposure


   Introduction
Top
 Abstract
 Introduction
Methods
 Results
 Discussion
 Conflicts of interest
 References
 
Hand–arm vibration syndrome (HAVS) is an occupational disease that may afflict workers who operate hand-held vibrating tools [1]. The risk of developing HAVS relates to a number of factors which include individual worker susceptibility, as well as the frequency, duration and amplitude of exposure [2]. Vibration may cause damage to the vascular, neurological and musculoskeletal systems of the upper limbs which may manifest as HAVS, carpal tunnel syndrome (CTS) or both [2,3]. The vascular component of HAVS is typified by cold-induced Raynaud's phenomenon, often referred to as attacks of ‘blanching’ or ‘white finger’. The neurological symptoms manifest as tingling and numbness in the fingers, resulting in reductions in sensory perception, tactile discrimination and manipulative dexterity. The musculoskeletal symptoms include pain, swelling and stiffness in the hands and wrists, and may result in reduced grip strength.

Collectively, the signs and symptoms of HAVS manifest as difficulty in using the hands in everyday activities both domestically and at work. HAVS may also increase the potential risk of accidents in the workplace, and impair job performance [4].

Rock drills have been used in South African gold-mines since 1907 [5], and are associated with high vibration magnitudes averaging between 24 and 31 m/s2 [6,7]. These levels are five to six times higher than the European Union exposure limit value of 5 m/s2, and 15 min of exposure per day would therefore exceed the recommended daily exposure limit value [2].

Prior to this study, HAVS had not previously been reported in South Africa, and no cases had been compensated under the Occupational Injuries and Diseases Act of 1993 [8].

The aim of this study was to determine the prevalence and severity of HAVS in South African gold miners, and to identify the tools responsible.


   Methods
Top
 Abstract
 Introduction
 Methods
Results
 Discussion
 Conflicts of interest
 References
 
Two occupational health doctors and seven technicians were trained in the clinical evaluation and standardized testing for HAVS by experienced occupational health practitioners from the UK Health and Safety Laboratory. The equipment used for the standardized testing of HAVS was purchased from the Institute of Sound and Vibration Research at the University of Southampton in the UK.

Participants were randomly selected from a list of all mineworkers from a single South African gold-mine (employing ~19 000 mineworkers) who returned from annual leave during the 6-month study period. Random numbers generated by Epi-info 6.0 statistical software were used to select participants. It was estimated that this recruitment period would generate a sample size with 95% power to detect a 10% difference in the prevalence of HAVS between exposed and non-exposed workers, while allowing for a 20% drop-out rate.

The objectives of the study were explained in the mineworker's home language and informed consent was obtained from each study participant. The investigation of mineworkers commenced with an interview, and review of medical and occupational histories. This included a detailed history of past and present work tasks, job titles and vibration exposure. The clinical assessment of HAVS was conducted by an occupational physician in accordance with the Health and Safety Laboratory, UK, protocol, blinded to the history of exposure. A technician (blinded to the occupational history and clinical findings) performed three standardized objective tests; thermal aesthesiometry, vibrotactile threshold and a cold provocation test, following the UK standardized protocol for HAVS assessment [9].

The temperatures in the mines were obtained from the mine records.

The data were analysed using SPSS 10.0 statistical software. Student t-tests were used to test the difference between the mean values of the subjects and comparison group. Where data were not normally distributed, the Wilcox–Mann–Whitney test was used. Chi-square analysis was used including Mantel–Haenszel statistics, Yates correction and Fischer exact test to compare data from subjects and the comparison group. The level for statistical significance was set at P = 0.05.

Ethics approval was obtained from the Committee for Research in Human Subjects (Medical) of the University of the Witwatersrand.


   Results
Top
 Abstract
 Introduction
 Methods
 Results
Discussion
 Conflicts of interest
 References
 
Over the study period, 311 mineworkers were randomly selected to participate and 296 completed the study (participation rate 95%). The participants were all black males; half were of South African origin, the remainder being from neighbouring countries. Following a detailed review of the occupational and social history, 156 workers were assigned to the exposed group, having a current (74%) or past (26%) history of occupational hand–arm vibration exposure. The comparison group comprised 140 workers with no history of vibration exposure at all. The majority of the vibration-exposed workers reported using rock drills (84%), with a smaller number using pick machines (8%), and the remainder using grinders, impact wrenches or small drills. The two groups were similar demographically, and there were no significant differences between the two groups in terms of age or duration of mine service (Table 1). The mean [standard deviation (SD)] ages of the exposed and non-exposed groups were 38 (6.8) and 39 (7.8) years, respectively. The mean (SD) cumulative services of the exposed and non-exposed groups were 14 (7.0) and 15 (7.9) years, respectively.


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  		Table 1 Distribution of exposed and non-exposed workers by age and service duration

 
Among the vibration-exposed group, the prevalence of HAVS was 15%, which equated to 24 miners. Of these, 13 had concurrent vascular and neurological symptoms, eight had neurological symptoms only and three had vascular symptoms only. The severity of HAVS as staged by the Stockholm Workshop scales are shown in Tables 2 and 3. The mean latent period between first exposure to vibration and the onset of symptomatic HAVS was 5.6 years (range 1–18 years). All the subjects with HAVS reported vibration exposure from rock drills.


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  		Table 2 Severity of HAVS among South African gold miners as assessed by Stockholm staging—sensorineural component

 

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  		Table 3 Severity of HAVS among South African gold miners as assessed by Stockholm staging—vascular component

 
Among the non-exposed comparison group, seven of 140 (5%) had signs and symptoms indistinguishable from HAVS. The prevalence of HAVS in the vibration-exposed group was significantly greater than the prevalence of HAVS-like conditions in the comparison group with a relative risk of 3.08 (95% CI: 1.37–6.92, P = 0.006).

Thirteen (8%) of the vibration-exposed and three (2%) of the comparison group had CTS. In seven subjects, CTS occurred together with HAVS. In the study mine, the mean wet bulb temperature in the stopes was 28.6°C.


   Discussion
Top
 Abstract
 Introduction
 Methods
 Results
 Discussion
Conflicts of interest
 References
 
In this study, vibration-exposed South African gold miners were three times more likely to report symptoms compatible with HAVS than non-exposed workers. The prevalence of HAVS in the exposed group was 15%, and in all cases this was associated with exposure to rock drills. The mean latency between first exposure to vibration and first symptoms was 5.6 years.

The cases of HAVS in this study were diagnosed and staged based on accepted criteria widely used within the UK [2], it is therefore highly likely that they represent valid cases.

A potential limitation of the study relates to the higher prevalence of co-morbid conditions that exist in developing countries [such as human immunodeficiency virus (HIV), alcoholism and antituberculous chemotherapy], which may cause symptoms similar to HAVS. While every attempt was made to allow for this by the use of a non-exposed comparison group, it was not possible to ascertain whether the groups had similar rates of co-morbidity.

The prevalence of HAVS was lower than might have been expected, given the magnitude of vibration previously measured with the rock drills [6,7]. Vascular attacks of blanching were reported by 10%, and tingling/numbness by 13% of the vibration-exposed gold miners. The prevalence of vascular symptoms has varied from 17 to 85% in previous studies of rock drillers [10–12]. The prevalence of sensorineural symptoms in studies of rock drillers has also varied from 8 to 81% [12–15]. The low prevalence of vascular symptoms (normally precipitated by the cold) in our study may in part have reflected the warm ambient work temperature (mean wet bulb temperature of 28.6°C). In other studies in warm countries such as India [13], Singapore [16] and Vietnam [14], vibration-exposed workers did not report blanching. Also, the prevalence of vascular symptoms in a Chinese study of railroad workers varied geographically, being higher in the colder north and north-eastern regions [17].

Vibration-exposed workers developing HAVS may also suffer from CTS [18]. Previous studies have found the prevalence of CTS to be 21.4% in Italian forestry workers [19], and 15% of UK miner claimants with HAVS were also diagnosed as having co-existing CTS [20]. The prevalence of CTS has been reported to be as high as 44% in rock drillers [21], but was much lower in this study at 8% of exposed workers.

Clearly, it is not possible to ascertain why the prevalence of symptoms was so low in this study, and it is unlikely that the climate is the only relevant factor. Vascular HAVS symptoms may improve after vibration exposure ceases [22], and it should be noted that approximately one-quarter of the vibration-exposed workers were not currently exposed. Another factor, which is also likely to be at least part of the explanation, relates to a survivor population effect. This is likely to have been even more of a factor in this study population due to two different mine screening programmes. Firstly, workers developing noise-induced hearing loss (which has previously been shown to be associated with HAVS [23]) are removed from further noisy drilling (vibration) exposures. Secondly, workers have their grip strength screened post-accidents, and those with inadequate grip are relocated. Since grip strength tends to diminish [24] and accidents tend to increase [25] with increasing severity of HAVS, it is possible that those with the most severe HAVS may have already been removed from drilling exposure. While some of these workers may have been relocated in non-vibration-exposed jobs (and therefore have still participated in the study as part of the previously exposed to vibration group), it is likely that some of these workers may have left employment.

The relatively low rate of HAVS may be due to variations in individual susceptibility. Little is known about this in relation to workers of different ethnic origin, and this area requires further study.

Although it has been reported that tools such as pick machines, grinders, small drills and impact wrenches can cause HAVS [2], none of the miners who reported exposure to these tools were found to be suffering from it. A possible explanation for this may have related to the small number of workers using these tools, and the associated lower vibration exposures of their work tasks [2].

HAVS has been reported after vibration exposures ranging from 1 month to 30 years, and this latent interval may be used as an indicator of the risk of a particular work task [26]. Generally, the shorter the average latent interval, the greater the risk to workers of early onset and progression to severe disease. Previous studies of vibration-exposed workers have demonstrated mean latent intervals of 2–17 years [27]. The mean latent interval for HAVS in the study gold miners was 5.6 years (range 1–18 years). This is similar to the 4.5- to 10.4-year range of median latencies previously reported among rock drillers [10,11,28].

Five per cent (7/140) of the controls had signs and symptoms, which were indistinguishable from those of HAVS, with 1% reporting vascular symptoms and 4% sensorineural. This is comparable to the findings of previous studies where the prevalence among non-exposed controls has been reported as 2.7–14% for vascular symptoms [13,19,29–31] and 2.3–16.3% for neurological symptoms [14,29,31–33].

This is the first report of HAVS in South African gold miners and marks the recognition of a scheduled condition compensatible under South African legislation (Compensation for Occupational Injuries and Disease Act, Act 130 of 1993) [8]. In the UK, HAVS has been associated with significant disability and impairment of quality of life, relating in particular to the sensorineural staging, and the presence of co-existing CTS [34]. The impact of HAVS in South African miners, where other significant health problems such as HIV positivity [35], tuberculosis [36], silicosis [37] and high alcohol consumption [38] are prevalent, is unknown and requires further study.

Subjects found to have HAVS in this study were offered medical advice, and those who continued to work with vibrating tools were followed up carefully.

Through the execution of this study, the National Institute for Occupational Health has been able to establish the first South African centre where workers can be referred for HAVS assessments. The South African mining industry now faces the challenge of implementing effective control measures to reduce vibration exposure from rock drills, and to develop effective health surveillance measures.


Key points
  • South African gold miners exposed to vibration from rock drills are at risk of HAVS.
  • The reasons for the lower than expected prevalence of HAVS in this group is unknown, and requires further study.
  • Mine medical officers need to be aware of the risk of HAVS in their workforce in order to take appropriate action and initiate the compensation process.

 


   Conflicts of interest
Top
 Abstract
 Introduction
 Methods
 Results
 Discussion
 Conflicts of interest
References
 
None declared.


   Acknowledgements
 
We would like to acknowledge the Safety in Mines Research Advisory Council of the Mines Health and Safety Council for funding this project. We would like to thank all the staff at the Driefontein Occupational Health Centre, Gold Fields International and those at the Mines Bureau for Occupational Disease, Johannesburg, South Africa. L. Allan of the Health and Safety Laboratory provided valuable assistance and training.


   References
Top
 Abstract
 Introduction
 Methods
 Results
 Discussion
 Conflicts of interest
 References
 

  1. Griffin MJ. (1997) Measurement evaluation and assessment of occupational exposures to hand transmitted vibration. Occup Environ Med 54:73–89.[Abstract/Free Full Text]

  2. HSE. (2005) Hand-Arm Vibration. The Control of Vibration at Work Regulations 2005: Guidance on Regulations L140(HSE Books, Sudbury).

  3. Pelmear PL. (1998) Clinical picture (vascular, neurological and musculoskeletal). In Pelmear PL and Wasserman DE (Eds.). Hand Arm Vibration Syndrome: A Comprehensive Guide for Occupational Health Professionals 2nd edn (OEM Press, Beverly Farms, MA) pp. 27–43.

  4. Pyykko I. (1986) Clinical aspects of the hand arm vibration syndrome: a review. Scand J Work Environ Health 12:439–447.[Web of Science][Medline]

  5. Watermeyer GA and Hoffenberg SN. (1932) History of the gold industry of the Rand. Witwatersrand Mining PracticeThe Transvaal Chamber Of Mines, Gold Producers' Committee.

  6. Van Niekerk JL, Heyns PS, Heyns M, Hassall JR. (1998) The Measurement of Vibration Characteristics of Mining Equipment and Impact Percussive Machines and Tools(Safety in Mines Research Advisory Committee, Braamfontein, South Africa) Report GEN 503.

  7. Heyns PS. (2003) Rock Drill Noise and Vibration Measurement(Safety in Mines Research Advisory Committee, Braamfontein, South Africa) Report HEALTH 806.

  8. Compensation for Occupational Injuries and Diseases Act,No. 130. (1993) http://www.labour.gov.za (date last accessed 9 August 2006).

  9. HSE. (1998) Standardised Diagnostic Methods for Assessing Components of the Hand-Arm Vibration Syndrome CRR197(HSE Books, Sudbury).

  10. Wasserman DE, Behrens VJ, Pelmear PL. (1991) Hand arm vibration syndrome in a group of US uranium miners exposed to hand arm vibration. Appl Occup Environ Hyg 6:183–187.

  11. Brubacker RL, Mackenzie CJG, Hutton SG. (1986) Vibration induced white finger among selected underground rock drillers in British Columbia. Scand J Work Environ Health 12:296–300.[Web of Science][Medline]

  12. Futatsuka M, Yasutaki N, Sakura T, Matsumoto T. (1985) Comparative study of vibration disease among operators of vibrating tools by factor analysis. Br J Ind Med 42:260–266.[Web of Science][Medline]

  13. Dasgupta AK and Harrison J. (1996) Effects of vibration on the hand arm system of miners in India. Occup Med (Lond) 46:71–78.

  14. Futatsuka M, Shono M, Shakakibara H, Quan PQ. (2005) Hand arm vibration syndrome among quarry workers in Vietnam. J Occup Health 47:165–170.[CrossRef][Web of Science][Medline]

  15. Bovenzi M, Franzinelli A, Strambi F. (1988) Prevalence of vibration induced white finger and assessment of vibration exposure among travertine workers in Italy. Int Arch Occup Environ Health 61:25–34.[CrossRef][Web of Science][Medline]

  16. Davies TAL, Glaser EM, Collins CP. (1957) Absence of Raynaud's phenomenon in workers using vibratory tools in a warm climate. Lancet 272:1014–1016.[Medline]

  17. Yu ZS, Chao H, Qiao L, Qian DS, Ye YH. (1986) Epidemiologic survey of vibration syndrome among riveters, chippers, and grinders in the railroad system of the People's Republic of China. Scand J Work Environ Health 12:289–292.[Web of Science][Medline]

  18. Wieslander G, Norback D, Gothe CJ, Juhlin L. (1989) Carpal tunnel syndrome and exposure to vibration, repetitive wrist movements and heavy manual work: a case referent study. Br J Ind Med 46:43–47.[Web of Science][Medline]

  19. Bovenzi M, Rui F, Versini W, et al. (2004) Hand-arm vibration syndrome and upper limb disorders associated with forestry work. Med Lav 95:282–296.[Medline]

  20. Burke FD, Lawson IJ, McGeoch KL, et al. (2005) Carpal tunnel syndrome in association with hand-arm vibration syndrome: a review of claimants seeking compensation in the mining industry. J Hand Surg [Br] 30:199–203.[CrossRef][Medline]

  21. Chatterjee DS, Barwick DD, Petrie A. (1982) Exploratory electromyography in the study of vibration induced white finger in rock drillers. Br J Ind Med 39:89–97.[Web of Science][Medline]

  22. Bovenzi M, Franzinelli A, Scattoni L, Vannuccini L. (1994) Hand-arm vibration syndrome among travertine workers: a follow-up study. Occup Environ Med 51:361–365.[Abstract/Free Full Text]

  23. Palmer KT, Griffin MJ, Sydall HE, Pannett B, Cooper C, Coggon D. (2002) Raynaud's phenomenon, vibration induced white finger, and difficulties in hearing. Occup Environ Med 59:640–642.[Abstract/Free Full Text]

  24. Banister PA and Smith EV. (1972) Vibration induced white finger and manipulative dexterity. Br J Ind Med 29:264–267.[Web of Science][Medline]

  25. Bovenzi M. (1998) Hand transmitted vibration. In Stellman JM, McCann M, Warshaw L, Brabant C (Eds.). Encyclopaedia of Occupational Health and Safety 4th edn (ILO, Geneva) pp. 50.7–50.12.

  26. Pelmear PL. (1994) Vibration: hand arm and whole body. In Raffle PAB, Adams PH, Baxter PJ, Lee WR (Eds.). Hunter's Diseases of Occupations 8th edn (Edward Arnold, London) pp. 308–323.

  27. Brammer AJ. (1982) Vibration effects on the hand arm in industry. (John Wiley & Sons, New York).

  28. Pelmear PL, Roos J, Leong D, Wong L. (1987) Cold provocation test results from a 1985 survey of hard rock miners in Ontario. Scand J Work Environ Health 13:343–347.[Web of Science][Medline]

  29. Mibord SM, Yoshida H, Komura Y, et al. (1994) Prevalence of Raynaud's phenomenon in different groups of workers operating hand held vibrating tools. Int Arch Occup Environ Health 66:13–22.[CrossRef][Web of Science][Medline]

  30. Silman A, Holligan S, Brennan P, Maddison P. (1990) Prevalence of symptoms of Raynaud's phenomenon in general practice. Br Med J 301:590–592.[Abstract/Free Full Text]

  31. Hellstrom B and Anderson KL. (1972) Vibration injuries in Norwegian forest workers. Br J Ind Med 29:255–263.[Web of Science][Medline]

  32. Futatsuka M, Yasutaki N, Sakura T, Matsumoto T. (1985) Comparative study of vibration disease among operators of vibrating tools by factor analysis. Br J Ind Med 42:260–266.[Web of Science][Medline]

  33. Bovenzi M. (1994) Hand arm vibration syndrome and dose response relation for vibration induced white finger among quarry drillers and stonecarvers. Occup Environ Med 51:603–611.[Abstract/Free Full Text]

  34. Mason HJ, Poole K, Elms J. (2005) Upper limb disability in HAVS cases-how does it relate to the neurosensory or vascular elements of HAVS? Occup Med (Lond) 55:389–392.

  35. Corbett EL, Charalambous S, Fielding K, et al. (2003) Stable incidence of tuberculosis (TB) among human immunodeficiency virus (HIV)—negative South African gold miners during a decade of epidemic HIV-associated TB. J Infect Dis 188:1156–1163.[CrossRef][Web of Science][Medline]

  36. Kleinschmidt I and Churchyard G. (1997) Variation in incidences of tuberculosis in subgroups of South African gold miners. Occup Environ Med 54:636–641.[Abstract/Free Full Text]

  37. Churchyard GJ, Ehrlich R, teWaterNaude JM, et al. (2004) Silicosis prevalence and exposure-response relations in South African gold miners. Occup Environ Med 61:811–816.[Abstract/Free Full Text]

  38. Eisler R. (2003) Health risks of gold miners: a synoptic review. Environ Geochem Health 25:325–345.[CrossRef][Web of Science][Medline]


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