This literature review assess the gap by examining the cost incurred due to poor working condition and offer ways for considering ergonomic solution in reducing MSDs to improve productivity, reduce workers’ compensation and healthcare costs. Musculoskeletal disorders are one of the main causes of occupational disorders and are highly associated with socioeconomic burden to individual, organization and society in general view. The purpose of this study is to determine the prevalence of musculoskeletal disorders and associated risk factors in metal manufacturing industry workers and summarize the findings associated and identify existing gaps.
The article summarizes publications on the subject area; identify existing gaps on impact of physical Ergonomics on Musculoskeletal Disorders (MSDs). Findings show, the working conditions in the work environment result in high absence rate among employees due to illness and work related musculoskeletal disorder. This results in lower productivity and higher medical and compensation cost Metal manufacturing industries are stressful, with poor safety, weak interfacing with work equipment as well as physical workplace layout design. Work environment conditions results revealed noise, vibration, climate, illumination, and working posture were not an acceptable limit as ergonomic perspective.
A LITERATURE REVIEW ON IMPACT OF PHYSICAL ERGONOMICS ON MUSCULOSKELETAL DISORDERS (MSDS) OF METAL MANUFACTURING INDUSTRIES
Abstract
Musculoskeletal disorders are one of the main causes of occupational disorders and are highly associated with socioeconomic burden to individual, organization and society in general view. The purpose of this study is to determine the prevalence of musculoskeletal disorders and associated risk factors in metal manufacturing industry workers and summarize the findings associated and identify existing gaps.
The article summarizes publications on the subject area; identify existing gaps on impact of physical Ergonomics on Musculoskeletal Disorders (MSDs). Findings show, the working conditions in the work environment result in high absence rate among employees due to illness and work related musculoskeletal disorder. This results in lower productivity and higher medical and compensation cost
Metal manufacturing industries are stressful, with poor safety, weak interfacing with work equipment as well as physical workplace layout design. Work environment conditions results revealed noise, vibration, climate, illumination, and working posture were not an acceptable limit as ergonomic perspective.
This literature review assess the gap by examining the cost incurred due to poor working condition and offer ways for considering ergonomic solution in reducing MSDs to improve productivity, reduce workers’ compensation and healthcare costs.
Keywords Physical ergonomics, musculoskeletal disorders, metal manufacturing industries
1. Introduction
Musculoskeletal disorder (MSD) is a worldwide occupational health problem and it affects all types of economic activities, with considerable costs and impact on workers’ quality of life. Poor working conditions in manufacturing industries often expose workers to many risk factors for musculoskeletal diseases. Occupational activities involving a predominance of manual tasks seem to present a higher risk of injury (Barbosa-Branco A., Souza W.R. 2011).
Manufacturing of metal products features high incidence of disability insurance claims and ranks as eighth among work-related claims (Barbosa-Branco A., Souza W.R. 2011). Workers in manufacturing industry are directly involved in the production process and could be exposed to different physical work demands such as lifting, lowering, pushing, pulling, and carrying besides dealing with heavy machinery.
The physical and chemical agents of potential health are present hazards in this industries in the raw materials, in the processing of raw materials or as by-products of the manufacturing process. A close observation of the metal manufacturing industries reveals that, workers are working in a hostile environment that is composed of Air Pollution, Noise Pollution, Poor illumination inadequate ventilation and high temperature, all through the production line.
The level of risk on the workers depends on the duration, frequency and magnitude of the exposure. Physical risk factors for MSD often cited in experimental and epidemiological studies include: repetitiveness, insufficient recovery time, physical workload, static effort, non-neutral body postures, mechanical compression of tissues, segmental or whole-body vibration and exposure to the cold (Punnett L. 2004).
There are many challenges when dealing these issues such as diagnosing and treating the MSD, establishing the relationship between risk factors and manual occupational activities as well as providing work environments that minimize their occurrence (Lamarão A.M 2014). Management’s insistence on good housekeeping and safety practices is also at its bare minimum. Though several environmental laws are enacted by the Governments, the situation in traditional has not improved over the decades of its existence.
The foregoing discussion on the work environment in metal Industries reveals that all sorts of job stress over are present in these industries to make the job severely straining to workers. This highlights the need for ergonomic appraisal of the work environment in metal industries. Therefore, this article concentrates on detecting the prevalence of musculoskeletal symptoms among metal manufacturing workers and finding the risk factors which had impact on this prevalence.
This paper comprises of five sections at first introduction second a structured, relevant literature review, third methodology used to accomplish the objectives of the fourth study, results and discussion followed by a conclusion.
1.1. Methods
In this literature, journal articles were reviewed which examine impact of physical ergonomic interventions on WMSD. Studies were found using search engine from internet databases: Science Direct, Academic Search Premier, and PubMed.gov by the National Institute of Health as well as the Summit Interlibrary. Search terms used were permutations of the following: Impact of Physical Ergonomic, work-related musculoskeletal disorders, ergonomic assessment, musculoskeletal disorders, ergonomics, and Metal manufacturing industries.
1.1.1. Inclusion Criteria
In selecting sources for this paper, a major inclusion criterion was the use of ergonomic interventions, which included any combination of posture changes, workstation design, ergonomics education, and organizational modifications. Sources that only addressed work related musculoskeletal disorders are included as they are the most common WMSD with the most available data. All sources included were written in English.
1.1.2. Exclusion Criteria
Sources that solely investigate traditional methods are not included in the analysis portion of this paper.
2. Literature Review
2.1. Work related musculoskeletal disorders
Work-related musculoskeletal disorders (WMSD) related with repetitive and demanding working conditions continue to represent one of the biggest problem in working condition. The World Health Organization (WHO), recognizing the impact of ‘work-related’ musculoskeletal diseases, has characterized WMSDs as multifactorial, indicating that a number of risk factors contribute to and exacerbates these disorders (Sauter et al., 1993).
WMSD disorders are aggravated by work that can affect the upper limb extremities, the lower back area, and the lower limbs. WMSD can be defined by impairments of bodily structures such as muscles, joints, tendons, ligaments, nerves, bones and the localized blood circulation system, caused or aggravated primarily by work itself or by the work environment (Nunes, 2009a).
Despite the variety of efforts to control WMSD, including engineering design changes, organizational modifications or working training programs, these set of disorders account for a huge amount of human suffering due to worker impairment, often leading to permanent, partial or total disability.
WMSD have also heavy economic costs to companies and to healthcare systems. The costs are due to loss of productivity, training of new workers and compensation costs. These costs are felt globally, particularly as organizations begin to develop international partnerships for manufacturing and service roles.
2.2 WMSD risk factors
The strong correlation between the incidence of WMSD and the working conditions is well known, particularly the physical risk factors associated with jobs e.g., awkward postures, high repetition, excessive force, static work, cold or vibration. Work intensification and stress and other psychosocial factors also seem to be factors that increasingly contribute to the onset of those disorders (EU-OSHA 2008; EU-OSHA 2011; HSE 2002; EUROFUND, 2007).
As referred WHO attributes a multifactorial etiology to WMSD, which means that these disorders appear as consequence of the worker exposure to a number of work related risk factors (WHO, 1985). Besides risk factors related to work other risk factors contribute to its development, namely factors intrinsic to the worker and factors unrelated to work. A risk factor is any source or situation with the potential to cause injury or lead to the development of a disease. The variety and complexity of the factors that contribute to the appearance of these disorders explains the difficulties often encountered, to determine the best suited ergonomic intervention to be accomplished in a given workplace, to control them.
Moreover, despite all the available knowledge some uncertainty remains about the level of exposure to risk factors that triggers WMSD. In addition there is significant variability of individual response to the risk factors exposure.
The literature review and epidemiological studies have shown that in the genesis of the WMSD three sets of risk factors can be considered (Bernard, 1997; Buckle & Devereux, 1999; Nunes, 2009a):
- Physical factors - e.g., sustained or awkward postures, repetition of the same movements, forceful exertions, hand-arm vibration, all-body vibration, mechanical compression, and cold;
- Psychosocial factors - e.g., work pace, autonomy, monotony, work/rest cycle, task demands, social support from colleagues and management and job uncertainty;
- Individual factors - e.g., age, gender, professional activities, sport activities, domestic activities, recreational activities, alcohol/tobacco consumption and, previous WMSD.
In order to evaluate the possibility of an employee develop WMSD it is important to include all the relevant activities performed both at work and outside work. Most of the WMSD risk factors can occur both at work and in leisure time activities.
Risk factors act simultaneously in a synergistic effect on a joint or body region. Therefore to manage risk factors it is advisable and important to take into account this interaction rather than focus on a single risk factor. Due to the high individual variability it is impossible to estimate the probability of developing WMSD at individual level.
2.1.1 Physical factors
A comprehensive review of epidemiological studies was performed to assess the risk factors associated with WMSDs (NIOSH, 1997). The review categorized WMSDs by the body part impacted including (1) neck and neck-shoulder, (2) shoulder, (3) elbow, (4) hand-wrist, and (5) back. The widely accepted physical or task-related risk factors include repetition, force, posture, vibration, temperature extremes, and static posture (NIOSH, 1997; McCauley Bush, 2011)
The physical risk factors are a subset of work related risk factors including the environment and biomechanical risk factors, such as posture, force, repetition, direct external pressure (stress per contact), vibration and cold. Another risk factor that affects all risk factors is duration. Since WMSD develop associated with joints, it is necessary that each of these risk factors is controlled for each joints of the human body. In Table 2 a compilation of physical risk factors by body area are presented.
2.1.2 Psychosocial factors
Psychosocial risk factors are non-biomechanical risk factors related with work. The work-related psychosocial factors are subjective perceptions that workers have of the organizational factors, which are the objective aspects of how the work is organized, is supervised and is carried out (Hagberg et al., 1995). Although organizational and psychosocial factors may be identical, psychosocial factors include the worker emotional perception. Psychosocial risk factors are related with work content (e.g., the work load, the task monotony, work control and work clarity), it organizational characteristics (for example, vertical or horizontal organizational structure), interpersonal relationships at work (e.g., relations supervisor-worker) and financial / economic aspects (e.g., salary, benefits and equity) and social (e.g., prestige and status in society) (NIOSH, 1997).
Psychosocial factors cannot be seen as risk factors that, by themselves, led to the development of WMSDs (Gezond heidsraad, 2000). However, in combination with physical risk factors, they can increase the risk of injuries, which has been confirmed by experience. Thus, if the psychological perceptions of the work are negative, there may be negative reactions of physiological and psychological stress. These reactions can lead to physical problems, such as muscle tension. On the other hand, workers may have an inappropriate behaviour at work, such as the use of incorrect working methods, the use of excessive force to perform a task or the omission of the rest periods required to reduce fatigue. Any these conditions can trigger WMSDs (Hagberg et al. 1995).
2.1.3 Individual or personal risk factors
The field of ergonomics does not attempt to screen workers for elimination as potential employees. The recognition of personal risk factors can be useful in providing training, administrative controls, and awareness. Personal or individual risk factors can impact the likelihood for occurrence of a WMSD (McCauley-Bell & Badiru, 1996a; McCauley-Bell & Badiru, 1996b). These factors vary depending on the study but may include age, gender, smoking, physical activity, strength, anthropometry and previous WMSD, and degenerative joint diseases (McCauley Bush, 2011).
Gender (McCauley Bush, 2011) women are three times more likely to have CTS than men (Women.gov, 2011). Women also deal with strong hormonal changes during pregnancy and menopause that make them more likely to suffer from WMSD, due to increased fluid retention and other physiological conditions. Other reasons for the increased presence of WMSDs in women may be attributed to differences in muscular strength, anthropometry, or hormonal issues. Generally, women are at higher risk of the CTS between the ages of 45 and 54. Then, the risk increases for both men and women as they age. Some studies have found a higher prevalence of some WMSDs in women (Bernard et al., 1997; Chiang et al., 1993; Hales et al., 1994), but the fact that more women are employed in hand-intensive jobs may account for the greater number of reported work-related MSDs among women.
Physical Activity (McCauley Bush, 2011)
Studies on physical fitness level as a risk factor for WMSDs have produced mixed results. Physical activity may cause injury. However, the lack of physical activity may increase susceptibility to injury, and after injury, the threshold for further injury is reduced. In construction workers, more frequent leisure time was related to healthy lower backs and severe low-back pain was related to less leisure time activity (Holmström et al., 1992). On the other hand, some standard treatment regimes have found that musculoskeletal symptoms are often relieved by physical activity. National Institute for Occupational Safety and Health (NIOSH, 1991) stated that people with high aerobic capacity may be fit for jobs that require high oxygen uptake, but will not necessarily be fit for jobs that require high static and dynamic strengths and vice versa.
Strength (McCauley Bush, 2011)
Epidemiologic evidence exists for the relationship between back injury and weak back strength in job tasks. Chaffin & Park (1973) found a substantial increase in back injury rates in subjects performing jobs requiring strength that was greater or equal to their isometric strength-test values. The risk was three times greater in weaker subjects. In a second longitudinal study, Chaffin et al. (1977) evaluated the risk of back injuries and strength and found the risk to be three times greater in weaker subjects. Other studies have not found the same relationship with physical strength. Two prospective studies of low-back pain reports (or claims) of large populations of blue collar workers (Battie et al., 1989; Leino, 1987) failed to demonstrate that stronger workers (defined by isometric lifting strength) are at lower risk for low back pain claims or episodes.
Anthropometry (McCauley Bush, 2011)
Weight, height, body mass index (BMI) (a ratio of weight to height squared), and obesity have all been identified in studies as potential risk factors for certain WMSDs, particularly CTS and lumbar disc herniation. Vessey et al. (1990) found that the risk for CTS among obese women was double that of slender women. The relationship of CTS and BMI has been suggested to be related to increased fatty tissue within the carpal canal or to increased hydrostatic pressure throughout the carpal canal in obese persons compared with slender persons (Werner et al, 1994). Carpal tunnel canal size and wrist size has been suggested as a risk factor for CTS; however, some studies have linked both small and large canal areas to CTS (Bleecker, et al., 1985; Winn & Habes, 1990). Studies on anthropometric data are conflicting, but in general indicate that there is no strong correlation between stature, body weight, body build, and low back pain. Obesity seems to play a small but significant role in the occurrence of CTS.
2.1.4 Interaction among risk factors
All risk factors interact among each other. For example, the stress felt by a worker may be influenced by the physical demands of the task, the psychological reaction to this requirement, or by both.
Once the requirement of the task reaches a high value, the worker may have stress reactions and biological and behavioral unsuitable reactions. As these reactions are more frequent and occur over an extended period they cause health problems. These health problems reduce the ‘resistance’ of individuals to cope with the subsequent demands of work, thus increasing the possibility of occurrence of WMSDs. As mentioned, the duration of exposure to risk factors is one of the parameters that must be taken into account when a risk assessment is performed. For example, the heuristic model dose-response (Figure 1) to cumulative risk factors in repetitive manual work, proposed by Tanaka McGlothlin, underlines the role of the duration of the activity in the development of musculoskeletal disorders of the hand / wrist (Tanaka & McGlothlin, 2001).
In the figure it’s possible to observe the interaction of the following risk factors: force, repetition and wrist posture with exposure duration. In order to keep workers operating in a safe area an increase in exposure duration should be accompanying with a reduction of the other risk factors There has been an increasing effort in recent years to investigate the causes of musculoskeletal disorders (MSDs) and to take action to prevent them. This has led to increasing recognition from workers, employers and government agencies that a strong relationship exists between factors within the working environment and the development of MSDs, and that these conditions result insignificant sickness absence and reduced productivity [Buckle P, Devereux J - 1999].
3. Discussion and Conclusion
Ergonomics is the application of scientific principles, methods drawn from a various disciplines for the development of engineering systems, the role of human is significant 2. Automation and advancement of technology lead to replacement of large amount of human resources in industrial systems, however, some tasks are being done manually by human resources 3.
During the manufacturing process iron melts at temperature of 16000C and collects at the bottom of the furnace. The waste gas from the blast furnace, which is rich in carbon monoxide, is burned in blast furnace stoves to heat the air blown into the furnace and may be used as a fuel elsewhere in the metal manufacturing plant. The majority of operations in the steel and power industry expose workers to a wide range of hazards or work place activities or conditions that could cause accidents which may lead to death, ill health or diseases.
Findings of many studies showed that many workers had musculoskeletal disorders in their work places. Lumbar, knee(s) and neck had most common musculoskeletal disorders prevalence. Musculoskeletal disorder has significant association with job duration and BMI of workers. In our searching on the literature, Ford et al. in their study on 1566 iron workers in United States reported back rejoin (56%) as the highest musculoskeletal disorders’ prevalence.21 Choi et al. reported that regardless of body part, the prevalence of musculoskeletal disorders was 25.5% among 2093 aging male metal workers (Choi WJ, 2009). In comparison with these studies, the prevalence of musculoskeletal disorders is higher. Substandard work places and inattention of workers to the caution instructions without national and effective preventive strategies or programs might be responsible for this higher rate. One of Lumbar, knee(s) and back symptoms were found to be the most frequent problem among the workers studied. This high prevalence might be due to awkward working postures, manual material handling and long hours of standing work, which were common at almost all workstations and job activities observed.
More complaints in lumbar and back were accompanied with the highest rates of sick leave. Interventional programs for prevention of occupational injuries in workplaces of workers must focus on reducing physical exposure to the musculoskeletal disorders risk factors of these regions.
Findings of many studies showed that job duration and BMI were significantly associated with musculoskeletal symptoms in the different body regions. BMI of workers had a role in improving their efficacy and obese workers had higher chance of musculoskeletal disorders and work related trauma.
Ergonomic programs change is required for BMI of workers and help to achieve suitable BMI and physical fitness. Previous researches showed that recently employed workers had more chance to encounter with occupational injuries than workers who have been employed for longer period of time. Patients with lower job duration did not have enough experience to meet risk factors because this situation had impacts on their interactions with workplaces and other workers and knowing about surrounding hazards (Svane O, 1987)
We need careful evaluations of steel workers and their workplaces for gathering more information to support or reject this idea. Among ergonomic risk factors such as awaked posture, repetitive motions, forceful excretion were present in our workstation in most metal manufacturing industries.
It was concluded that musculoskeletal disorders in metal manufacturing industries occurred in high rate. We recommended additional studies to be performed for accurate assessment of musculoskeletal disorders risk factors. Noted programs must focus on reducing physical exposure to the musculoskeletal disorders risk factors of these regions.
Works referred to
Choi WJ, Kang YJ, Kim JY, Han SH. Symptom prevalence of musculoskeletal disorders and the effects of prior acute injury among aging male steelworkers. J Occup Health 2009;51:273-82. 19372627 [doi.org/10.1539/joh.O8025]
Svane O. National prevention of musculoskeletal workplace injury: Denmark--a summary. Ergonomics 1987; 30:181-4. 3582328 [doi.org/ 10.1080/00140138708969691]
Frequently asked questions
What is the main topic of "A LITERATURE REVIEW ON IMPACT OF PHYSICAL ERGONOMICS ON MUSCULOSKELETAL DISORDERS (MSDS) OF METAL MANUFACTURING INDUSTRIES"?
The literature review focuses on the impact of physical ergonomics on musculoskeletal disorders (MSDs) in metal manufacturing industries. It examines the prevalence of MSDs, associated risk factors, existing gaps in research, and potential ergonomic solutions to improve productivity and reduce healthcare costs.
What are musculoskeletal disorders (MSDs)?
MSDs are occupational health problems affecting muscles, joints, tendons, ligaments, nerves, and bones. They are often caused or aggravated by work itself or the work environment.
What are the primary risk factors for WMSDs in metal manufacturing?
The review identifies physical factors (e.g., awkward postures, repetitive movements, forceful exertions, vibration), psychosocial factors (e.g., work pace, autonomy, monotony, stress), and individual factors (e.g., age, gender, physical activity, previous MSDs) as key risk factors.
What are some examples of physical risk factors in metal manufacturing industries?
Examples include sustained or awkward postures, repetition of the same movements, forceful exertions, hand-arm vibration, whole-body vibration, mechanical compression, and exposure to cold.
What are psychosocial risk factors, and how do they contribute to WMSDs?
Psychosocial risk factors are non-biomechanical factors related to work, such as work pace, autonomy, monotony, work/rest cycle, task demands, social support, and job uncertainty. They can increase the risk of injuries when combined with physical risk factors by causing stress, tension, and inappropriate work behaviors.
What are some individual risk factors that might increase the likelihood of WMSDs?
Individual risk factors include age, gender, smoking, physical activity, strength, anthropometry (body measurements), and previous WMSDs or degenerative joint diseases. Women may be at higher risk of MSDs due to hormonal changes, differences in muscular strength, and other physiological conditions.
Why are WMSDs a significant concern?
WMSDs result in worker impairment, potentially leading to partial or total disability, human suffering, lost productivity, training costs, and compensation costs. The review suggests that the working conditions in the work environment result in high absence rate among employees due to illness and work related musculoskeletal disorder.
What ergonomic interventions can be implemented to reduce WMSDs in metal manufacturing industries?
The literature review assess the gap by examining the cost incurred due to poor working condition and offer ways for considering ergonomic solution in reducing MSDs to improve productivity, reduce workers’ compensation and healthcare costs. Specific interventions aren't fully detailed but imply changes in posture, workstation design, ergonomics education, and organizational modifications could be applied.
What is the role of BMI in WMSDs?
The review highlights the association between Body Mass Index (BMI) and the risk of musculoskeletal disorders. Obese workers are found to have a higher chance of experiencing musculoskeletal disorders and work-related trauma.
What is the importance of addressing both physical and psychosocial risk factors?
All risk factors interact among each other and act simultaneously in a synergistic effect on a joint or body region. To manage risk factors effectively, it is advisable to take into account this interaction rather than focus on a single risk factor. Negative psychological perceptions of the work can lead to physical problems, such as muscle tension and can trigger WMSDs.
- Quote paper
- Kassu Jilcha (Author), 2014, Physical ergonomics and work-related musculoskeletal disorders (MSDS). A literature review, Munich, GRIN Verlag, https://www.grin.com/document/933762
