Identification of Ergonomics Risk Factors in the Fishery Industry

Transcription

1 Identification of Ergonomics Risk Factors in the Fishery Industry Rosnah Mohd Yusuff *, Rohaizad Mohd. Daud and Norzima Zulkifli Department of Mechanical and Manufacturing, Faculty of Engineering, Universiti Putra Malaysia, 43400, Serdang, Selangor *Corresponding author ABSTRACT: In Malaysia, the fishery industry is a source of employment for many workers. The workers in the fishery industry are involved with many activities such as capturing, processing and marketing of the fishes. Most of the work is done manually which put the workers at risks to musculoskeletal disorders (MSDs). These are health hazards that affect the nerves, tendons, muscles, and supporting structures such as inter vertebral discs. However, the occurrence or the degree of severity of MSDs on the workers has never been investigated. A preliminary investigation to identify the ergonomics risk factors among the workers in the fishery industry has been conducted. The location chosen for this study was at a jetty where fishing boats arrived and the fishes were loaded onshore. Various task were conducted and these tasks pose some ergonomic risks. PLIBEL checklist questionnaires were used on forty workers at the jetty and observations of the tasks performed were made. A survey was done on the body posture, working habits and activities of the workers. The results from the PLIBEL checklist showed that the upper back, hands/wrists and ankles/feet were at greater risks of developing into MSDs compared to the other body parts. REBA analysis was used to evaluate the postural risks of the workers on five tasks. The REBA analysis showed that some of the work postures posed greater risks of MSDs to the workers with REBA scores between seven and eleven. This indicated that the job has to be redesigned for the tasks to be safer, healthier and more comfortable to the workers. Keywords: musculoskeletal disorders, fishery industry, REBA, NIOSH lifting equation. 1. INTRODUCTION Fishery industry involves many activities, such as in capture, processing and marketing. In Malaysia, the fishery industry is under the Ministry of Agriculture. The fisheries sector is an important sub-sector in Malaysia and plays a significant role in the national economy. Apart from contributing to the national Gross Domestic Product (GDP), it is also a source of employment, foreign exchange and a source of protein supply for the rural population in the country. In 1997, the fisheries sector contributed 1.57% to GDP, and it provides employment for more than fishermen and fish farmers (Food and Agriculture Organization of the United Nations, 2007). The capturing, processing and marketing of fish is predominantly manual and requires the fisherman to adopt various awkward postures in conducting their tasks. Many studies have shown that work-related musculoskeletal disorders develop when a major part of a worker s job involves reaching, bending over, lifting heavy objects, using continuous force, working with vibrating equipment, and doing repetitive motions. These injuries affect muscles, nerves, tendons, ligaments, joints, or spinal discs. Bending, twisting, kneeling, reaching, and stretching in particular are stressors on the low back and influence how the worker feel after finishing a taxing task. Bovenzi et al., (1992) and Ishibashi (1998) suggested that factors such as frequent awkward postures, muscular effort, vibration, shock, and whole body vibration exposure and finally prolonged sitting in a constrained position contribute to overwork of the lumbar spine and its supportive structures, causing low back pain. Most studies on the occurrence of MSDs involving fisherman were done on vessels. Swedish studies on fishermen have shown that symptoms from the musculoskeletal system were common, and that they follow a logical pattern according to the fishing and type of working tasks on board. Among the small scale coastal fisherman studied, seventy-seven per cent experienced symptoms of the musculoskeletal system during the previous 12 months of the survey, 61% low back pain and 37% shoulder pain. The largest number of fishermen considered the motion of the vessel to be a major strain, not only on the musculoskeletal system, but on the individual as a whole (Törner et al., 1988). A higher prevalence of symptoms of the upper limbs was found among those with jobs involving high repetitiveness or forceful movements, as compared to those who had jobs with low repetitiveness and low-force movements.

2 Rosnah Mohd Yusuff et al./ The 9 th Southeast Asian Ergonomics Society Conference (Page 2) MSDs can cause a number of conditions, including pain, numbness, tingling stiff joints, difficulty moving, muscle loss and sometimes paralysis. The conditions that are likely to cause MSD problems are exerting excessive force, excessive repetition of movements that can irritate tendons and increase pressure on nerves, awkward postures or unsupported positions, static postures or positions that a worker must hold for long periods of time. These risk factors either alone or in combination can subject workers shoulders, arms, hands, wrists, backs and legs to thousands of repetitive twisting, forceful or flexing motions during a typical workday (U.S Department of Labor, 2000). Parts of the body affected by MSDs are arms, hands, fingers, neck, back, wrists, legs and shoulders. Musculoskeletal impairments ranked number one in chronic impairments in the United States, and chronic musculoskeletal pain is reported in surveys by 1 in 4 people in less and more developed countries (White and Harth cited in Anthony D. Woolf and Kristina Akesson, 2001). Musculoskeletal disorders (MSDs) are among the leading causes of occupational injury and disability, with back pain the most common reason for the filing of workers compensation claims. It accounts for about one fourth of all claims and for about 40 percent of absences from work. In the United States, in 1990, the cost of back pain was estimated to be between $50 billion and $100 billion (Saporta, 2000). No studies have been found on the ergonomics risks of workers involved in the fishery industry in Malaysia. Postural analysis of work activities can be used to identify and evaluate the ergonomics risks encountered by the workers and initiate changes in the ways work is carried out. This study was conducted to identify the ergonomic problems faced by these workers and the tasks that are causing them. Solutions to alleviate the problems can then be considered. 2. METHODOLOGY In applying ergonomics to real situations, on site observation of the tasks carried out to identify the ergonomic stress factors is important. The use of a checklist during the on-site observation to identify ergonomic stressors of tasks carried out will ensure that all the relevant information will be collected. A checklist is useful as it provide us with a preliminary evaluation of the tasks, identifying and directing our attention to the problem areas. Further investigations and recommendations or intervention programs can then be developed. Usually, PLIBEL is used to identify risk factors for musculoskeletal injuries of a specific body region, which means that only questions relevant to that body region need to be answered (Kemmlert, 1995). This study was conducted on forty workers carrying various tasks at the jetty in the northern state of Malaysia, where the fishes were unloaded from the boats to the shores to be processed at the factories. Demographic information such as age and years of experience were asked. The workers were asked whether in general, any of their body parts experience pain. The PLIBEL checklist was administered verbally. The PLIBEL checklist was used for the identification of musculoskeletal stress factors that may have injurious effect on various body parts. The workers were shown the body part diagram to enable them identify areas of the body having problems more easily. Their work postures were also observed and photographs taken for further analysis. The movements and position of the body parts were determined from the videotaping and photographs. Rapid Entire Body Assessment (REBA) analysis was used to evaluate the posture of the workers. The REBA provides a quantitative value to the evaluation that indicates the level of severity of each task. The calculation was made by using the REBA Employee Assessment Worksheet that has been divided into two groups; Group A (Trunk, Neck and Legs) postures and Group B (Upper Arms, Lower Arms and Wrists) postures for left and right. A summary of the procedure for REBA score and the degree of risk is found in the REBA decision table (Hignett and McAtamney, 2000). The risk score of this approach should be in the range of one to fifteen, where the higher scores signify greater levels of apparent risk. The REBA scores will be translated into REBA action levels as shown in Table 1:

3 Rosnah Mohd Yusuff et al./ The 9 th Southeast Asian Ergonomics Society Conference (Page 3) Table 1 : REBA Action Level Action Level REBA score Risk Level Action( including further Assessment) 0 1 Negligible Not necessary Low Maybe necessary Medium Necessary High Necessary soon Very High Necessary NOW Five postures were analysed: 1. Lifting fishes from the jute (net) 2. Carrying the fishes from the boat to the pulley 3. Move up the basket to the jetty (with pulley) 4. Move the fishes to the jetty (manual handling) 5. Lifting the basket on to the trolley 3. RESULTS AND DISCUSSIONS 3.1 Work observations From observations, it was seen that the workers constantly bend and twist their backs head and shoulders in picking and placing the loads. The hands and wrist were frequently used in carrying the tasks at undesirable positions. Based on the photographs and video taken, the angle of movements of the trunk, neck, lower arm, wrists and positions of the legs and upper arms were estimated. These values are required in establishing the scores in REBA. Photographs of the different tasks carried out are found in Figures 1 to PLIBEL checklist By using the PLIBEL checklist, musculoskeletal stress factors that have injurious effects can be identified. Forty fishermen participated in this study. Most of the fishermen were in the age range between and having less than 10 years of working experience. Only five of the fishermen had more than 20 years of working experience. The result of the PLIBEL checklist is shown in Table 1. The wrist/hands had the most number of problems (118) followed by upper back (99), ankles/feet (63), lower back (28), shoulders (15), neck (11), knees (5) and elbows (1). The upper back has been identified as the part that felt fatigue most often (19) followed by the lower back (12). It also required movement most often (15) and the part that feel ache or pain after the task (16). The part that has to be moved repetitively the most and feels numb most often were the wrists/hands by 23 and 26 workers respectively. The ankles/feet had the most occurrence of consultation with paramedics because of physical problems (18) and experiences that affect the job (18). Workers performing hand intensive tasks and repetitive motion are more prone to develop upper extremity wmsds. The onset and severity of hand and wrists WMSDs with the performance of repetitive and forceful hand-intensive tasks have been found in epidemiological studies and can be worsened by performing the tasks in the presence of awkward or extreme wrist and forearm postures, cold temperatures, and vibration (Barr et al., 2004). All wmsds will naturally progress to worsen over time and may eventually lead to permanent disability if there is no intervention. It requires serious attention and immediate response to alleviate the problems. Problems of the hand and wrists may lead to carpal tunnel syndrome, strains, sprains, tendinitis and other hand related diseases which are painful, and in some cases surgery. The effect of the ergonomic risks on the ankles/feet and hands/wrists may have been manifested as the workers indicated that these were

4 Rosnah Mohd Yusuff et al./ The 9 th Southeast Asian Ergonomics Society Conference (Page 4) the most frequent parts requiring paramedic consultation because of physical problems and as experiencing pain affecting their job performance. This is probably due to the prolonged standing in awkward postures, force exertion and repetition while performing the tasks. Complaints of back pain are usually rare as the upper back/the thoracic region is strong and stable to support the weight of the upper body. Upper back pain, is pain that is felt between the bottom of the neck and top of the lumbar spine. The most common cause of upper back pain is believed to originate from muscular irritation or other soft tissue (e.g. ligament) problems. These can arise from lack of strength, poor posture, overuse injuries (such as repetitive motion), or a trauma (such as a car accident or sports injury). Another cause of upper back pain is problems with the joints that connect the vertebrae and the ribs. (Wikipedia, Although upper back pain is not a very common spinal disorder, it can cause significant discomfort and pain when it does occur. The most common causes of upper back pain are muscular irritation (myofascial pain) and joint dysfunction (Talbot, J.S. DO Also, the prolonged malposture of the head on the neck may cause muscle fatigue, pain, and stiffness because of steady contraction of the muscle-tendon unit and deviation from normal body posture. The US Department of Labor identified RSIs as the fastest growing workplace injuries, and can result any time there is a mismatch between physical requirement of the job and the physical capacity of the human body. According to a 1993 Occupational Safety & Health Administration document, employers reported 1 of 4 lost-time injuries and illnesses due to RSIs to the Bureau of Labor Statistics ( cases in 1993 represented 32% involving upper extremities) (Reich RB, owadisp.show_document?p_table=speeches&p_id=206). 3.3 REBA Analysis REBA was conducted to evaluate individual s exposure to postures, forces and muscles activities. All the activities studied have the potential to contribute to MSDs as indicated by the PLIBEL checklist. Based on observations and photographs taken, a postural analysis based on REBA was used. Each tasks was analysed and scored. A sample of the calculation is shown in Table 3 using the steps described by Hignett and McAtamney (2000). The tasks analysed and the summarized results for all the REBA scores for each are shown in figures 1-5. Table 2: PLIBEL Checklist for 40 workers at the Jetty in Kuala Kedah Questions (rate Y for yes, N for no) 1. Fatigue because of operation most often? 2. Which part required for movement most often (rate from 1-5)? 3. Which parts need to exert forces most often? 4. Which part required moving repetitively? 5. Which part feels numb often? 1. Neck 2. Shoulders 3. Upper back 4. Elbows 5. Lower back 6. Wrists/ hands 7. Hips/ Thigh 8. Knees 9.Ankles /feet

5 Rosnah Mohd Yusuff et al./ The 9 th Southeast Asian Ergonomics Society Conference (Page 5) 6. Parts that feel ache or pain after tasks? 7. Ever consult paramedic because of physical problem? 8. Ever experience problem which affect your job? 9. Any part which lack of support which leads to discomfort or pain? The posture of the workers involved in the tasks evaluated showed that substantial repetitive bending is required, turning and twisting, the use of hands and wrists and require force. The REBA score for three tasks was 7, one 9 and the other 11. This showed that the risk level for REBA score 7 is medium indicating that action and further assessment is required, a score of 9 showed a high risk level and require action soon and a score of 11 as having very high risk and immediate action is necessary. The REBA score confirmed the findings from the checklist as the excessive bending resulted in the occurrence of fatigue experienced in the upper and lower back of the operators. The over-use of the wrists and hands resulted in numbness and some of the workers had to seek paramedics for treatment. Table 3: REBA Score for Workers lifting fishes from jute (sample calculation) A. Neck, Trunk and Leg Analysis SCORE Step 1 Locate Neck Position +2 Step 2 Locate Trunk Position +4 Step 3 Legs +1 Step 4 Look-up Posture Score +5 in Table A Step 5 Add Force/Load Score +1 Score A: + 6 in Table C B. Arm and Wrist Analysis SCORE Step 7 Locate Upper Arm Position +2

6 Rosnah Mohd Yusuff et al./ The 9 th Southeast Asian Ergonomics Society Conference (Page 6) Step 8 Locate Lower Arm Position +2 Step 9 Locate Wrist Position +1 Step 10 Look-up Posture Score +2 in Table B Step 11 Add Coupling Score +1 Score B : +3 in Table C Activity Score +1 + Table C Score + 6 Total Score +7 Table 4: REBA score and Task Descriptions. Tasks REBA score Risk Level Task description Medium Action is The workers have to lift necessary the fishes from the net. Prolonged stooping and trunk bend at more than Stress to the Upper and lower back Figure 1: Workers lifting fishes from jute High The workers carried the Action necessary fishes from the basket to soon the pulley before moving up to the jetty. Trunk bent at more than 90 degrees. Stress to the neck, hand, foot, lower and upper back Figure 2: Workers carrying fishes

7 Rosnah Mohd Yusuff et al./ The 9 th Southeast Asian Ergonomics Society Conference (Page 7) Medium Action is necessary This task also requires prolonged bending. Figure 3: Move up the basket to jetty (using pulley) Very high Immediate action is necessary A lot of energy is expended to carry and lift the basket from the boat to the jetty. Stress to the back and hand Figure 4 : Move up fishes to Jetty (manual handling) Medium Action is necessary The basket is placed on the trolley. Twisting and bending of the back. Figure 5: Lifting the basket on the trolley 4. CONCLUSION AND RECOMMENDATIONS The study has identified the body parts and tasks of the workers exposed to ergonomic risks through the PLIBEL checklists and the REBA method respectively. Results from the study showed that majority of the workers were having WMSDs. Symptoms such as pain in the upper and lower back, hand/wrists and ankles/feet if not resolved will deteriorate to permanent disability. The work design should be improved to improve the posture, followed by shortening the duration of prolonged standing by providing adequate breaks and reducing the number of repetition on a particular tasks. Often, those who did work at the jetty are the same who went out with the boats. Their problems maybe aggravated further.

8 Rosnah Mohd Yusuff et al./ The 9 th Southeast Asian Ergonomics Society Conference (Page 8) The WMSDs problems can be reduced if the workers are trained and know the correct working postures. The employer plays an important role in educating their workers on the proper way of manual handling. The tasks should also be redesigned to ensure work is conducted with proper posture and designed based on the capabilities and limitations of the workers thus, increasing the efficiency, productivity and safety to health and environment. Pesco et al. (2006) found that increased postural self-awareness to correct poor posture as potentially useful means for reducing upper back and neck pain due to repetitive stress, overwork, and stiffness. REFERENCES [1] Barr, A.E., Barbe, M.F. and Clark, B.D Work-Related Musculoskeletal Disorder of Hands and Wrist: Epidemiology, Pathophysiology, and Sensorimotor Changes. J Orthop Sports Phys Ther., October 2004; 34 (10). pp [2] Bovenzi, M. and Zadini, A. (1992). Self-reported low back symptoms in urban bus drivers exposed to whole body vibration. Spine 17. pp [3] Food and Agriculture Organization of the United Nations, Accessed on 20th September [4] Hignett, S. and McAtamney, L., Rapid Entire Body Assessment (REBA). Applied Ergonomics, Vol pp [5] Ishibasi, T., and Sagyo, U., (1998). Sagyo Hiro Handbook. Rodo-Kijun-Chosakai In: Y. Saito (Ed.), Tokyo, pp [6] Kemmlert, K., A Method assigned for the Identification of Ergonomic Hazards- PLIBEL. Applied Ergonomics, Vol.26, No.3. pp [7] National Institute for Occupational Safety and Health (NIOSH). Musculoskeletal disorders and workplace factors. U.S. Department of Health and Human Services, [8] NIOSH (1981). Work Practices Guide for Manual Lifting, NIOSH Technical Report No US Department of Health and Human Services, NIOSH, Cincinatti, OH. [9] Pesco, M.S, Chosa, E., and Tajima, N Comparative study of Hands on Therapy with Active Exercises and Education with active Exercises For the Management of Upper Back Pain. J Manipulative Physiol Ther 2006; 29. pp [10] Reich RB. Preventing repetitive stress injuries. U.S. Depart-ment of Labor. OSHA Archive Report Available from: Accessed on 20 September 2008 [11] Saporta, H., (2000). Durable ergonomic seating for urban bus operators. Tri-Country Metropolitan Transportation District of Oregon. Accessed on 21 September [12] Talbot J. Sellers, DO Accessed on 10 September [13] Tornër, T., Blide, G.,Eriksson, H., Kadefors, R., Karlsson, R. and Petersen, I., Workload and Ergonomics Measures in Swedish Professional Fishing. Applied Ergonomics, pp [14] U.S Department of Labor, (2000). Occupational Safety and Health Administration OSHA (Revised) [15] Wikipedia. [16] Woolf, A. D. and Akesson, K., (2001). Understanding the burden of musculoskeletal conditions BMJ.322: , 5 May 2001.