AMERICAN JOURNAL OF INDUSTRIAL MEDICINE 57:476–485 (2014)
Risks of Musculoskeletal Disorders among Betel Quid Preparers in Taiwan Jer-Hao Chang,
PhD,
1
Jyun-De Wu, PhD,2 Chih-Yong Chen, PhD,3 Shih-Bin Su, Hsin-I Yin, MS,2 and Der-Jen Hsu, PhD6
MD, PhD,
4,5
Background Betel quid chewing is common in Taiwan. The work of betel quid preparers is characterized by long hours of static work, awkward working posture and highly repetitive hand/wrist motion. However, the musculoskeletal health of betel quid preparers receives very little attention. Methods The Chinese version of the Standardized Nordic Musculoskeletal Questionnaire (NMQ) was administered, and electrogoniometers and electromyography were used in this cross-sectional study to characterize the hand/wrist motion of the subjects. Physical examinations on the thumbs and wrists of the subjects were conducted by means of Phalen’s test and Finkelstein’s test, respectively. Results Among the 225 participants, more than 95% attributed their musculoskeletal complaints to their work, and shoulder, neck, hand/wrist, and lower back discomfort were most frequently reported. More than 70% of the preparers did not seek medical treatment for their musculoskeletal problems. Based on the physical examination, 24% of the participants had suspected symptom of either carpal tunnel syndrome (CTS) or DeQuervain’s tenosynovitis. The instrumental measurements indicated that betel quid preparation is characterized by extreme angle ranges and moderate repetition of wrist motion as well as low forceful exertion. Conclusions This study concludes that betel quid preparers are a high risk group of developing musculoskeletal disorders (MSDs). Future studies by electrogoniometers and detailed physical examination on betel quid preparers are needed to determine the predisposing factors for CTS. Some intervention measures to prevent MSDs and to lessen psychological stress for this group of workers are strongly suggested. Am. J. Ind. Med. 57:476–485, 2014. ß 2014 Wiley Periodicals, Inc. KEY WORDS: betel quid preparer; carpal tunnel syndrome; DeQuervain’s tenosynovitis; musculoskeletal disorders; nordic musculoskeletal questionnaire
1
Department of Occupational Therapy, National Cheng-Kung University,Tainan,Taiwan Department of Occupational Safety and Health, Chang-Jung Christian University,Tainan,Taiwan Institute of Occupational Safety and Health, Council of LaborAffairs, ExecutiveYuan,Taipei,Taiwan 4 Department of Family Medicine, Chi-Mei Medical Center,Tainan,Taiwan 5 Institute of Biomedical Engineering, SouthernTaiwan University,Tainan,Taiwan 6 Department of Safety, Health and Environmental Engineering, National Kaohsiung First University of Science and Technology, Kaohsiung,Taiwan Contract grant sponsor: Institute of Occupational Safety and Health (IOSH) of Taiwan; Contract grant number: IOSH97-H316. Correspondence to:Der-Jen Hsu,Department of Safety,Health and Environmental Engineering,National Kaohsiung First University of Science and Technology,Kaohsiung,Taiwan. E-mail: [email protected] 2 3
Accepted 23 December 2013 DOI10.1002/ajim.22300. Published online 24 January 2014 in Wiley Online Library (wileyonlinelibrary.com).
ß 2014 Wiley Periodicals, Inc.
Ergonomic Hazard of Betel Quid Preparers
INTRODUCTION Musculoskeletal disorders (MSDs) are a common health problem globally and a major cause of disability in many occupations [Roquelaure et al., 2002; Choobineh et al., 2007]. Musculoskeletal complaints are also one of the most important problems which ergonomists encounter in workplaces [Thomsen et al., 2007; Wang et al., 2007]. While greater attention has been focused on musculoskeletal problems in major industries with substantial work forces, some small-scale and/or family-oriented occupations are overlooked. Betel quid preparation in Taiwan is one such occupation. Roadside booths which sell betel quid are commonly seen along the streets in Taiwan. Betel quid chewing is common in western Pacific basin and south Asia and approximately 200 million people are habitual chewers [Rooney, 1993; Gupta and Ray, 2004]. It is not only an important social activity, but also serves many cultural roles. Many habitual users chew betel quid during virtually all waking hours and appear to be psychologically and physiologically addicted to betel quid chewing [Pickwell et al., 1994]. Approximately 10% of the adults in Taiwan are habitual chewers of betel quid and the average annual consumption is about 10 kg per person [DGBAS, 2010]. Betel quid preparation is tedious work involving repetitive hand/wrist motion. When preparing betel quid, preparers need to spread lime onto betel leaf with a spread knife or brush. For each preparation, the hand with a spread knife/brush needs to repetitively move back and forth for about five times. After lime spreading, both thumbs and other fingers need to wrap a betel nut into the betel leaf in a very fast pace. Figure 1 is the schematic diagram of a betel quid preparer in work. In addition to the repetitive hand/wrist motion, the preparation work is also characterized by long hours of static sitting posture. Many studies have shown that carpet weavers and computer office workers, whose work is characterized by long hours of static work, are associated with musculoskeletal complaints [Choobineh et al., 2007; Eltayeb et al., 2009; Nag et al., 2010]. Other studies indicated that workers involved in poultry and fish processing, characterized by repetitive hand/wrist motion, are at risk of developing hand/wrist musculoskeletal symptoms [Chiang et al., 1993; Ohlsson et al., 1994; Lipscomb et al., 2007]. Consequently, betel quid preparers are hypothesized to be a high risk group of developing MSDs due to their repetitive hand/wrist motion. Many studies have reported the association between the psychological risk factors and MSDs [Heuvel et al., 2005; Murphy et al., 2007; Paananen et al., 2010]. Betel quid preparers in Taiwan are generally characterized by low income and social support, and are usually the focus of media. One noteworthy marketing strategy of betel quid is that many female preparers are required to wear sexy costumes brandishing in a glassy roadside booth to promote sales, in
477
addition to their preparation work. This unique culture of betel quid market in Taiwan has rendered preparers the criticism of public opinion. Thus, the psychological stress of betel quid preparers is an issue needs to be concerned. Although many betel quid-related studies have been performed previously, they have been entirely focused on the association between betel quid consumption and diseases such as oral leukoplakia, submucous fibrosis, and oral cancers [Thongsuksai and Boonyaphiphat, 2001; Zhang and Reichart, 2007]. Relatively little is known about the musculoskeletal problems of smaller scale and non-industrial betel quid preparers. The biomechanical characteristics of betel quid preparation have not been reported in the literature either. Therefore, this study hypothesized that betel quid preparation work is associated with MSD discomforts and psychological stress. The specific aims of this study are (1) to investigate the prevalence of the musculoskeletal discomfort and psychological stress among the betel quid preparers in Taiwan; (2) to characterize the wrist/thumb motion and muscular contraction during preparation work. To the best of our knowledge, this study is the first ergonomic study involving betel quid preparers. In this paper, the prevalence of MSD discomfort in this occupation is presented and the major factors associated with the musculoskeletal symptoms are discussed. Additionally, the results of physical examination on the wrists and thumbs of betel quid preparers are reported, and the association between MSDs prevalence and the results of physical examination are discussed. The characteristics of wrist/ thumb motion and muscular contraction involving in betel quid preparation by biomechanical measurements are also presented in this paper.
METHODS Subjects A total of 386 betel quid preparers in the roadside betel quid booths in southern Taiwan, based on sampling of convenience, were approached. The subjects were identified by both themselves and their work. Among the approached, 225 of them who completed the questionnaire and physical examination were included as participants and were cash compensated, giving a participation rate of 58.3%. This study was conducted during the period between June 2008 and January 2009. The ages of the participants ranged from 18 to 60 years (mean age ¼ 35.2, SD ¼ 9.8). All subjects except seven were right-handed according to the self-reported handedness. In order not to cause their job interruption, only 30 right-handed subjects out of the 225 preparers agreed to undergo the instrumental measurements. This study was approved by the Human Subjects Committee of Chang Jung Christian University (CJCU-97-001) and all the participants signed an informed consent form.
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Chang et al.
FIGURE1. Schematic diagram of (a) a betel quid preparer in work; (b) lime-spreading task.
Questionnaire The survey was administered by the well-trained investigators who interviewed each subject. The survey contained two major sections, one asking about demographic and employment information and the other asking about MSDs symptoms. The MSDs symptoms were surveyed by using the Chinese version of the standardized Nordic Musculoskeletal Questionnaire (NMQ) [IOSH, 2001], which is a translated version of the standardized NMQ by Kuorinka et al. [1987]. A simple body figure with nine highlighted areas was incorporated in the questionnaire to help interviewees answer “yes” or “no” to the question of whether they had experienced musculoskeletal discomfort of a particular body part in the past 12 months. A prevalent case was counted when the interviewee answered “yes” to the question. If “yes” was answered, history of occupational injury and medical treatments were also collected. The interview also included some self-reported questions on psychological stress, such as insomnia and the anxiety resulted from the media attention or the demanding work pace required by the employers. Types of responses for these questions were either multiple choice or open-ended questions.
Physical Examination Since betel quid preparers were observed to have highly repetitive hand/wrist motion, physical examination was performed on these body parts. Physical examination on the wrists and the thumbs of the betel quid preparers were
performed through Phalen’s test and Finkelstein’s test, respectively. Phalen’s test is one common physical examination to screen if a subject is suffering from carpal tunnel syndrome (CTS), while Finkelstein’s test is used to screen for DeQuervain’s tenosynovitis [Ramadan, 1997]. To perform Phalen’s test, the subjects were asked to hold their wrists in complete and forced flexion (pushing the dorsal surfaces of both hands together) for 30–60 s. This maneuver moderately increases the pressure in the carpal tunnel and has the effect of pinching the median nerve between the proximal edge of the transverse carpal ligament and the anterior border of the distal end of the radius. By compressing the median nerve within the carpal tunnel, characteristic symptoms (such as burning, tingling or a numb sensation over the thumb, index, middle, and ring fingers) convey a positive test result and suggest CTS [Urbano, 2000]. When Finkelstein’s test was performed, subject’s thumb was grasped and the hand was ulnar deviated sharply by the examiner. If a sharp pain occurs along the distal radius, DeQuervain’s tenosynovitis is likely [Finkelstein, 1930].
Instrumental Measurements Two biaxial electrogoniometers (model SG 75, Biometrics Ltd, Gwent, UK) and two single-axis electrogoniometers (model F 35, Biometrics Ltd) were attached on the wrists and thumbs of the subject, respectively, using the protocols from previous studies [Rawes et al., 1996; Chang et al., 2005]. A portable Biometrics DataLOG (model P3 8) was used to record the motion angles of flexion/extension and radial/ulnar deviation in both wrists and the flexion/extension in both
Ergonomic Hazard of Betel Quid Preparers
thumbs during preparation work. The flexible electrogoniometer consists of a central strain gauged flexible shim with two sensor endblocks attached to the shim for collecting the data of the relative motion of the two endblocks. The subjects can easily wear the flexible electrogoniometer to perform their daily activities without any hindrance and the instrument was tested to have better accuracy than the universal goniometer and fluid goniometer [Goodwin et al., 1992]. The flexible electrogoniometers were calibrated by the manufacturer before our work began and all subjects were asked to rest their hands and wrists on a table to calibrate the sensors to zero before data collection. The reliability and validity of this method have been reported in several studies [Ojima et al., 1992; Rawes et al., 1996]. Two bipolar electrodes (model SX230, Biometrics Ltd) were placed over the extensor carpi radialis and flexor carpi radialis of the subject’s dominant hand to record electromyography (EMG) activity, which was then used to calculate the percentage of maximal voluntary contraction (%MVC). The maximal voluntary contraction of the subject was obtained by securing her forearm on a table and asking her to perform the extreme wrist flexion and extension against the maximum resistance set by the examiner. The sampling rate of the sensors was set at 100 Hz for electrogoniometers and 1,000 Hz for EMG. The recording duration was 20 min of continuous preparation work for sufficient data collection.
Data Analysis Statistical analyses were performed using SPSS (version 12) and SAS (version 9.1). Descriptive statistics of the demographic data of the participants were calculated. Univariate logistic regression was first performed to identify the risk factors associated with the discomfort in each body part. Then, the risk factors with significance (P < 0.05) in the univariate analyses were selected to examine the odds ratio (OR) associated with the discomfort in each body part by multivariate logistic regression analyses. The stepwise approach set up at a significant level of 0.25 was used as the screening criterion for selecting the potential risk factors for the multivariate logistic regression analyses. The risk factor identified as significant in the multivariate logistic regression analysis provided the statistically estimated effect on the discomfort in each body part after considering all other risk factors in the analysis.
RESULTS Prevalence and Characteristics of MSDs The demographic and employment information of the study population are summarized in Table I. The betel quid preparers were predominately female (87.6%, n ¼ 197). Their
479
TABLE I. Demographic and Employment Information among Participants of the Betel Quid Cross-Sectional Study (n ¼ 225) Collected June 2008 to January 2009
Factors Gender Male Female Age (year) BMI Handedness Right Left Education level Primary and junior high High school/dropout College Ownership status Owner Employee Work seniority Daily work-hour Weekly work-day Weekly work-hour Number of betel quid prepared per day Average time to prepare a betel quid (s) Work-related cut Yes No Occupational stress Yes No
Numbers or mean
Percentage or SD (range)
28 197 35.2 21.5
12.4% 87.6% 9.8 (18^60) 3.2 (15.1^33.3)
218 7
96.9% 3.1%
67 142 16
29.8% 63.1% 7.1%
113 112 6.9 11.2 6.7 75.8 1,157 6.9
50.2% 49.8% 6.7 (0.1^40) 3.4 (3.0^20.0) 0.6 (2.0^7.0) 24.7 (8.0^140.0) 603.4 (80^3,500) 3.2 (2.1^23.4)
150 75
66.7% 33.3%
93 132
41.3% 58.7%
seniority for this work was averaged as 6.9 years. The average daily and weekly work hours were 11.2 and 75.8 hr, respectively. Our records showed that 73.8% of them worked more than 9 hr per day and 70% worked more than 90 hr per week. The average number of betel quid prepared by the participants per day was 1,150, though large variation was observed. Among the participants, 41.3% suffered from insomnia and other forms of psychological stress. According to the percentage of discomfort in different body parts in the past 12 months reported by the betel quid preparers, shoulder (71.1%), neck (58.2%), hand/wrist (53.3%) and lower back (48.9%) were the four most commonly reported body parts. Additionally, nearly 80% of them experienced discomfort in two or more body parts and only 18 participants (8%) reported no MSDs symptoms in the last 12 months. Table II shows the characteristics and treatments of the musculoskeletal discomfort in the four main body parts in the subjects. As shown, over 95% of them attributed their musculoskeletal discomfort to their preparation job. As for the severity of the symptom, 96–99% of them
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Chang et al.
TABLE II. Characteristics and Treatments of the Discomfort in Four Main Body Parts of the Subjects Discomfort in four body parts Symptom of musculoskeletal discomfort Sore and pain (%) Others (%) Frequency of musculoskeletal discomfort At least once per week (%) At most once per month (%) Work performance affected Affected (%) Not affected (%) Attributed to preparation job (%) Types of medical treatment Ignore or self-treatment (%) Traditional Chinese medical treatment (%) Western medical treatment (%) Both of the above two (%) Treatments contents overall Massage (%) Pain medication (%) Others (%)
Shoulder (n ¼160)
Neck (n ¼131)
Hand/wrist (n ¼120)
Lower back (n ¼110)
98.8 13.8
99.2 9.2
95.8 50.0
99.1 5.5
81.9 17.5
80.9 18.3
83.3 16.6
86.4 13.5
23.1 76.9 95.6
22.9 76.3 94.7
22.5 77.5 95.8
20.9 80.0 98.2
71.3 16.3 8.8 3.1
68.7 15.3 11.5 3.8
75.0 14.2 9.2 1.7
70.0 18.1 9.1 4.5
44.4 10.0 23.8
50.4 13.0 22.1
39.2 9.2 20.0
38.2 11.8 19.1
experienced soreness and pain as the most common compliant, and 21–24% of them reported that the MSDs symptoms had influenced their work or daily activities. Multivariate logistic regression analysis for estimating the odds ratio (OR) of having MSDs symptom in the four most commonly reported body parts (Table III) showed that working as an employee was a significant factor for neck discomfort with OR of 2.51 (95% CI 1.29–4.89). Work year was important in preventing or protecting against neck and lower back discomfort with OR of 0.40 (95% CI 0.20–0.81) and 0.27 (95% CI 0.08–0.89), respectively. Concerning work duration, daily work hour of 10–12 hr and more than 13 hr were found to be a significant risk factor for the discomfort in lower back with OR of 2.55 (95% CI 1.21–5.38) and 3.11 (95% CI 1.26–7.67), respectively. Working 7 days a week was also found to be a significant factor for neck problem with OR of 1.98 (95% CI 1.02–3.85). Workload is generally associated with the musculoskeletal discomfort and such association was also found in the current study. Preparation of 1,000–1,299 betel quid per day was an important factor for discomfort in the shoulder (OR ¼ 2.34, 95% CI 1.11–4.95), hand/wrist (OR ¼ 2.29, 95% CI 1.14–4.57) and lower back (OR ¼ 5.28, 95% CI 2.49–11.20). A strong association was also found in hand/wrist and lower back discomfort for those who preparing more than 1,300 betel quid per day, with OR of 3.79 (95% CI 1.81–7.94) and 2.29 (95% CI 1.09–4.82), respectively. Based on the OR of the complaint in hand/wrist, it increased with the number of betel quid prepared per day. This indicated that a significant dose–response relationship
exists between the hand/wrist complaint and the number of betel quid prepared per day. As mentioned earlier, only 18 subjects (8%) reported no musculoskeletal problem in any body part. Based on the survey, the average number of betel quid prepared each day by those 18 subjects was 839, significantly fewer than the average number of the other 207 subjects with MSDs discomfort (1,185 per day; P < 0.05). This finding reinforced our explanation about the effect of workload on the prevalence of MSDs among betel quid preparers. Lastly, working under stress was a risk factor for discomfort in shoulder (OR ¼ 2.37, 95% CI 1.18–4.73), hand/wrist (OR ¼ 2.12, 95% CI 1.14–3.97), and lower back (OR ¼ 2.05, 95% CI 1.09–3.83).
Physical Examinations and Biomechanical Analyses The results of the physical examination showed that 24% (54 over 225) of the subjects had significant discomforts in either hand/wrist or thumb. Among the 225 participants, 24 right wrists and 16 left wrists had positive response to Phalen’s test and 13 subjects suffered in both wrists. For Finkelstein’s test, 42 right thumbs and 26 left thumbs were tested to be positive while 17 subjects had both thumbs suffered. There were 24 subjects (10.7%) showed positive response to physical examination in both wrist and thumb. Table IV characterizes the motion angles and frequency for both wrists and thumbs during betel quid preparation. The data in the table indicate that the preparers performed
Ergonomic Hazard of Betel Quid Preparers
481
TABLE III. Multivariate Logistic Regression Analysis of Individual and Occupational Factors Associated with the Four Major Discomfort Areas OR (95% CI) Risk factor Ownership Owner Employed Work year
Risks of Musculoskeletal Disorders among Betel Quid Preparers in Taiwan Jer-Hao Chang,
PhD,
1
Jyun-De Wu, PhD,2 Chih-Yong Chen, PhD,3 Shih-Bin Su, Hsin-I Yin, MS,2 and Der-Jen Hsu, PhD6
MD, PhD,
4,5
Background Betel quid chewing is common in Taiwan. The work of betel quid preparers is characterized by long hours of static work, awkward working posture and highly repetitive hand/wrist motion. However, the musculoskeletal health of betel quid preparers receives very little attention. Methods The Chinese version of the Standardized Nordic Musculoskeletal Questionnaire (NMQ) was administered, and electrogoniometers and electromyography were used in this cross-sectional study to characterize the hand/wrist motion of the subjects. Physical examinations on the thumbs and wrists of the subjects were conducted by means of Phalen’s test and Finkelstein’s test, respectively. Results Among the 225 participants, more than 95% attributed their musculoskeletal complaints to their work, and shoulder, neck, hand/wrist, and lower back discomfort were most frequently reported. More than 70% of the preparers did not seek medical treatment for their musculoskeletal problems. Based on the physical examination, 24% of the participants had suspected symptom of either carpal tunnel syndrome (CTS) or DeQuervain’s tenosynovitis. The instrumental measurements indicated that betel quid preparation is characterized by extreme angle ranges and moderate repetition of wrist motion as well as low forceful exertion. Conclusions This study concludes that betel quid preparers are a high risk group of developing musculoskeletal disorders (MSDs). Future studies by electrogoniometers and detailed physical examination on betel quid preparers are needed to determine the predisposing factors for CTS. Some intervention measures to prevent MSDs and to lessen psychological stress for this group of workers are strongly suggested. Am. J. Ind. Med. 57:476–485, 2014. ß 2014 Wiley Periodicals, Inc. KEY WORDS: betel quid preparer; carpal tunnel syndrome; DeQuervain’s tenosynovitis; musculoskeletal disorders; nordic musculoskeletal questionnaire
1
Department of Occupational Therapy, National Cheng-Kung University,Tainan,Taiwan Department of Occupational Safety and Health, Chang-Jung Christian University,Tainan,Taiwan Institute of Occupational Safety and Health, Council of LaborAffairs, ExecutiveYuan,Taipei,Taiwan 4 Department of Family Medicine, Chi-Mei Medical Center,Tainan,Taiwan 5 Institute of Biomedical Engineering, SouthernTaiwan University,Tainan,Taiwan 6 Department of Safety, Health and Environmental Engineering, National Kaohsiung First University of Science and Technology, Kaohsiung,Taiwan Contract grant sponsor: Institute of Occupational Safety and Health (IOSH) of Taiwan; Contract grant number: IOSH97-H316. Correspondence to:Der-Jen Hsu,Department of Safety,Health and Environmental Engineering,National Kaohsiung First University of Science and Technology,Kaohsiung,Taiwan. E-mail: [email protected] 2 3
Accepted 23 December 2013 DOI10.1002/ajim.22300. Published online 24 January 2014 in Wiley Online Library (wileyonlinelibrary.com).
ß 2014 Wiley Periodicals, Inc.
Ergonomic Hazard of Betel Quid Preparers
INTRODUCTION Musculoskeletal disorders (MSDs) are a common health problem globally and a major cause of disability in many occupations [Roquelaure et al., 2002; Choobineh et al., 2007]. Musculoskeletal complaints are also one of the most important problems which ergonomists encounter in workplaces [Thomsen et al., 2007; Wang et al., 2007]. While greater attention has been focused on musculoskeletal problems in major industries with substantial work forces, some small-scale and/or family-oriented occupations are overlooked. Betel quid preparation in Taiwan is one such occupation. Roadside booths which sell betel quid are commonly seen along the streets in Taiwan. Betel quid chewing is common in western Pacific basin and south Asia and approximately 200 million people are habitual chewers [Rooney, 1993; Gupta and Ray, 2004]. It is not only an important social activity, but also serves many cultural roles. Many habitual users chew betel quid during virtually all waking hours and appear to be psychologically and physiologically addicted to betel quid chewing [Pickwell et al., 1994]. Approximately 10% of the adults in Taiwan are habitual chewers of betel quid and the average annual consumption is about 10 kg per person [DGBAS, 2010]. Betel quid preparation is tedious work involving repetitive hand/wrist motion. When preparing betel quid, preparers need to spread lime onto betel leaf with a spread knife or brush. For each preparation, the hand with a spread knife/brush needs to repetitively move back and forth for about five times. After lime spreading, both thumbs and other fingers need to wrap a betel nut into the betel leaf in a very fast pace. Figure 1 is the schematic diagram of a betel quid preparer in work. In addition to the repetitive hand/wrist motion, the preparation work is also characterized by long hours of static sitting posture. Many studies have shown that carpet weavers and computer office workers, whose work is characterized by long hours of static work, are associated with musculoskeletal complaints [Choobineh et al., 2007; Eltayeb et al., 2009; Nag et al., 2010]. Other studies indicated that workers involved in poultry and fish processing, characterized by repetitive hand/wrist motion, are at risk of developing hand/wrist musculoskeletal symptoms [Chiang et al., 1993; Ohlsson et al., 1994; Lipscomb et al., 2007]. Consequently, betel quid preparers are hypothesized to be a high risk group of developing MSDs due to their repetitive hand/wrist motion. Many studies have reported the association between the psychological risk factors and MSDs [Heuvel et al., 2005; Murphy et al., 2007; Paananen et al., 2010]. Betel quid preparers in Taiwan are generally characterized by low income and social support, and are usually the focus of media. One noteworthy marketing strategy of betel quid is that many female preparers are required to wear sexy costumes brandishing in a glassy roadside booth to promote sales, in
477
addition to their preparation work. This unique culture of betel quid market in Taiwan has rendered preparers the criticism of public opinion. Thus, the psychological stress of betel quid preparers is an issue needs to be concerned. Although many betel quid-related studies have been performed previously, they have been entirely focused on the association between betel quid consumption and diseases such as oral leukoplakia, submucous fibrosis, and oral cancers [Thongsuksai and Boonyaphiphat, 2001; Zhang and Reichart, 2007]. Relatively little is known about the musculoskeletal problems of smaller scale and non-industrial betel quid preparers. The biomechanical characteristics of betel quid preparation have not been reported in the literature either. Therefore, this study hypothesized that betel quid preparation work is associated with MSD discomforts and psychological stress. The specific aims of this study are (1) to investigate the prevalence of the musculoskeletal discomfort and psychological stress among the betel quid preparers in Taiwan; (2) to characterize the wrist/thumb motion and muscular contraction during preparation work. To the best of our knowledge, this study is the first ergonomic study involving betel quid preparers. In this paper, the prevalence of MSD discomfort in this occupation is presented and the major factors associated with the musculoskeletal symptoms are discussed. Additionally, the results of physical examination on the wrists and thumbs of betel quid preparers are reported, and the association between MSDs prevalence and the results of physical examination are discussed. The characteristics of wrist/ thumb motion and muscular contraction involving in betel quid preparation by biomechanical measurements are also presented in this paper.
METHODS Subjects A total of 386 betel quid preparers in the roadside betel quid booths in southern Taiwan, based on sampling of convenience, were approached. The subjects were identified by both themselves and their work. Among the approached, 225 of them who completed the questionnaire and physical examination were included as participants and were cash compensated, giving a participation rate of 58.3%. This study was conducted during the period between June 2008 and January 2009. The ages of the participants ranged from 18 to 60 years (mean age ¼ 35.2, SD ¼ 9.8). All subjects except seven were right-handed according to the self-reported handedness. In order not to cause their job interruption, only 30 right-handed subjects out of the 225 preparers agreed to undergo the instrumental measurements. This study was approved by the Human Subjects Committee of Chang Jung Christian University (CJCU-97-001) and all the participants signed an informed consent form.
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Chang et al.
FIGURE1. Schematic diagram of (a) a betel quid preparer in work; (b) lime-spreading task.
Questionnaire The survey was administered by the well-trained investigators who interviewed each subject. The survey contained two major sections, one asking about demographic and employment information and the other asking about MSDs symptoms. The MSDs symptoms were surveyed by using the Chinese version of the standardized Nordic Musculoskeletal Questionnaire (NMQ) [IOSH, 2001], which is a translated version of the standardized NMQ by Kuorinka et al. [1987]. A simple body figure with nine highlighted areas was incorporated in the questionnaire to help interviewees answer “yes” or “no” to the question of whether they had experienced musculoskeletal discomfort of a particular body part in the past 12 months. A prevalent case was counted when the interviewee answered “yes” to the question. If “yes” was answered, history of occupational injury and medical treatments were also collected. The interview also included some self-reported questions on psychological stress, such as insomnia and the anxiety resulted from the media attention or the demanding work pace required by the employers. Types of responses for these questions were either multiple choice or open-ended questions.
Physical Examination Since betel quid preparers were observed to have highly repetitive hand/wrist motion, physical examination was performed on these body parts. Physical examination on the wrists and the thumbs of the betel quid preparers were
performed through Phalen’s test and Finkelstein’s test, respectively. Phalen’s test is one common physical examination to screen if a subject is suffering from carpal tunnel syndrome (CTS), while Finkelstein’s test is used to screen for DeQuervain’s tenosynovitis [Ramadan, 1997]. To perform Phalen’s test, the subjects were asked to hold their wrists in complete and forced flexion (pushing the dorsal surfaces of both hands together) for 30–60 s. This maneuver moderately increases the pressure in the carpal tunnel and has the effect of pinching the median nerve between the proximal edge of the transverse carpal ligament and the anterior border of the distal end of the radius. By compressing the median nerve within the carpal tunnel, characteristic symptoms (such as burning, tingling or a numb sensation over the thumb, index, middle, and ring fingers) convey a positive test result and suggest CTS [Urbano, 2000]. When Finkelstein’s test was performed, subject’s thumb was grasped and the hand was ulnar deviated sharply by the examiner. If a sharp pain occurs along the distal radius, DeQuervain’s tenosynovitis is likely [Finkelstein, 1930].
Instrumental Measurements Two biaxial electrogoniometers (model SG 75, Biometrics Ltd, Gwent, UK) and two single-axis electrogoniometers (model F 35, Biometrics Ltd) were attached on the wrists and thumbs of the subject, respectively, using the protocols from previous studies [Rawes et al., 1996; Chang et al., 2005]. A portable Biometrics DataLOG (model P3 8) was used to record the motion angles of flexion/extension and radial/ulnar deviation in both wrists and the flexion/extension in both
Ergonomic Hazard of Betel Quid Preparers
thumbs during preparation work. The flexible electrogoniometer consists of a central strain gauged flexible shim with two sensor endblocks attached to the shim for collecting the data of the relative motion of the two endblocks. The subjects can easily wear the flexible electrogoniometer to perform their daily activities without any hindrance and the instrument was tested to have better accuracy than the universal goniometer and fluid goniometer [Goodwin et al., 1992]. The flexible electrogoniometers were calibrated by the manufacturer before our work began and all subjects were asked to rest their hands and wrists on a table to calibrate the sensors to zero before data collection. The reliability and validity of this method have been reported in several studies [Ojima et al., 1992; Rawes et al., 1996]. Two bipolar electrodes (model SX230, Biometrics Ltd) were placed over the extensor carpi radialis and flexor carpi radialis of the subject’s dominant hand to record electromyography (EMG) activity, which was then used to calculate the percentage of maximal voluntary contraction (%MVC). The maximal voluntary contraction of the subject was obtained by securing her forearm on a table and asking her to perform the extreme wrist flexion and extension against the maximum resistance set by the examiner. The sampling rate of the sensors was set at 100 Hz for electrogoniometers and 1,000 Hz for EMG. The recording duration was 20 min of continuous preparation work for sufficient data collection.
Data Analysis Statistical analyses were performed using SPSS (version 12) and SAS (version 9.1). Descriptive statistics of the demographic data of the participants were calculated. Univariate logistic regression was first performed to identify the risk factors associated with the discomfort in each body part. Then, the risk factors with significance (P < 0.05) in the univariate analyses were selected to examine the odds ratio (OR) associated with the discomfort in each body part by multivariate logistic regression analyses. The stepwise approach set up at a significant level of 0.25 was used as the screening criterion for selecting the potential risk factors for the multivariate logistic regression analyses. The risk factor identified as significant in the multivariate logistic regression analysis provided the statistically estimated effect on the discomfort in each body part after considering all other risk factors in the analysis.
RESULTS Prevalence and Characteristics of MSDs The demographic and employment information of the study population are summarized in Table I. The betel quid preparers were predominately female (87.6%, n ¼ 197). Their
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TABLE I. Demographic and Employment Information among Participants of the Betel Quid Cross-Sectional Study (n ¼ 225) Collected June 2008 to January 2009
Factors Gender Male Female Age (year) BMI Handedness Right Left Education level Primary and junior high High school/dropout College Ownership status Owner Employee Work seniority Daily work-hour Weekly work-day Weekly work-hour Number of betel quid prepared per day Average time to prepare a betel quid (s) Work-related cut Yes No Occupational stress Yes No
Numbers or mean
Percentage or SD (range)
28 197 35.2 21.5
12.4% 87.6% 9.8 (18^60) 3.2 (15.1^33.3)
218 7
96.9% 3.1%
67 142 16
29.8% 63.1% 7.1%
113 112 6.9 11.2 6.7 75.8 1,157 6.9
50.2% 49.8% 6.7 (0.1^40) 3.4 (3.0^20.0) 0.6 (2.0^7.0) 24.7 (8.0^140.0) 603.4 (80^3,500) 3.2 (2.1^23.4)
150 75
66.7% 33.3%
93 132
41.3% 58.7%
seniority for this work was averaged as 6.9 years. The average daily and weekly work hours were 11.2 and 75.8 hr, respectively. Our records showed that 73.8% of them worked more than 9 hr per day and 70% worked more than 90 hr per week. The average number of betel quid prepared by the participants per day was 1,150, though large variation was observed. Among the participants, 41.3% suffered from insomnia and other forms of psychological stress. According to the percentage of discomfort in different body parts in the past 12 months reported by the betel quid preparers, shoulder (71.1%), neck (58.2%), hand/wrist (53.3%) and lower back (48.9%) were the four most commonly reported body parts. Additionally, nearly 80% of them experienced discomfort in two or more body parts and only 18 participants (8%) reported no MSDs symptoms in the last 12 months. Table II shows the characteristics and treatments of the musculoskeletal discomfort in the four main body parts in the subjects. As shown, over 95% of them attributed their musculoskeletal discomfort to their preparation job. As for the severity of the symptom, 96–99% of them
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TABLE II. Characteristics and Treatments of the Discomfort in Four Main Body Parts of the Subjects Discomfort in four body parts Symptom of musculoskeletal discomfort Sore and pain (%) Others (%) Frequency of musculoskeletal discomfort At least once per week (%) At most once per month (%) Work performance affected Affected (%) Not affected (%) Attributed to preparation job (%) Types of medical treatment Ignore or self-treatment (%) Traditional Chinese medical treatment (%) Western medical treatment (%) Both of the above two (%) Treatments contents overall Massage (%) Pain medication (%) Others (%)
Shoulder (n ¼160)
Neck (n ¼131)
Hand/wrist (n ¼120)
Lower back (n ¼110)
98.8 13.8
99.2 9.2
95.8 50.0
99.1 5.5
81.9 17.5
80.9 18.3
83.3 16.6
86.4 13.5
23.1 76.9 95.6
22.9 76.3 94.7
22.5 77.5 95.8
20.9 80.0 98.2
71.3 16.3 8.8 3.1
68.7 15.3 11.5 3.8
75.0 14.2 9.2 1.7
70.0 18.1 9.1 4.5
44.4 10.0 23.8
50.4 13.0 22.1
39.2 9.2 20.0
38.2 11.8 19.1
experienced soreness and pain as the most common compliant, and 21–24% of them reported that the MSDs symptoms had influenced their work or daily activities. Multivariate logistic regression analysis for estimating the odds ratio (OR) of having MSDs symptom in the four most commonly reported body parts (Table III) showed that working as an employee was a significant factor for neck discomfort with OR of 2.51 (95% CI 1.29–4.89). Work year was important in preventing or protecting against neck and lower back discomfort with OR of 0.40 (95% CI 0.20–0.81) and 0.27 (95% CI 0.08–0.89), respectively. Concerning work duration, daily work hour of 10–12 hr and more than 13 hr were found to be a significant risk factor for the discomfort in lower back with OR of 2.55 (95% CI 1.21–5.38) and 3.11 (95% CI 1.26–7.67), respectively. Working 7 days a week was also found to be a significant factor for neck problem with OR of 1.98 (95% CI 1.02–3.85). Workload is generally associated with the musculoskeletal discomfort and such association was also found in the current study. Preparation of 1,000–1,299 betel quid per day was an important factor for discomfort in the shoulder (OR ¼ 2.34, 95% CI 1.11–4.95), hand/wrist (OR ¼ 2.29, 95% CI 1.14–4.57) and lower back (OR ¼ 5.28, 95% CI 2.49–11.20). A strong association was also found in hand/wrist and lower back discomfort for those who preparing more than 1,300 betel quid per day, with OR of 3.79 (95% CI 1.81–7.94) and 2.29 (95% CI 1.09–4.82), respectively. Based on the OR of the complaint in hand/wrist, it increased with the number of betel quid prepared per day. This indicated that a significant dose–response relationship
exists between the hand/wrist complaint and the number of betel quid prepared per day. As mentioned earlier, only 18 subjects (8%) reported no musculoskeletal problem in any body part. Based on the survey, the average number of betel quid prepared each day by those 18 subjects was 839, significantly fewer than the average number of the other 207 subjects with MSDs discomfort (1,185 per day; P < 0.05). This finding reinforced our explanation about the effect of workload on the prevalence of MSDs among betel quid preparers. Lastly, working under stress was a risk factor for discomfort in shoulder (OR ¼ 2.37, 95% CI 1.18–4.73), hand/wrist (OR ¼ 2.12, 95% CI 1.14–3.97), and lower back (OR ¼ 2.05, 95% CI 1.09–3.83).
Physical Examinations and Biomechanical Analyses The results of the physical examination showed that 24% (54 over 225) of the subjects had significant discomforts in either hand/wrist or thumb. Among the 225 participants, 24 right wrists and 16 left wrists had positive response to Phalen’s test and 13 subjects suffered in both wrists. For Finkelstein’s test, 42 right thumbs and 26 left thumbs were tested to be positive while 17 subjects had both thumbs suffered. There were 24 subjects (10.7%) showed positive response to physical examination in both wrist and thumb. Table IV characterizes the motion angles and frequency for both wrists and thumbs during betel quid preparation. The data in the table indicate that the preparers performed
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TABLE III. Multivariate Logistic Regression Analysis of Individual and Occupational Factors Associated with the Four Major Discomfort Areas OR (95% CI) Risk factor Ownership Owner Employed Work year
