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Review of Research on the Reduction of Cumulative Musculoskeletal Injuries1

Key Findings and Recommendations for Research on Cumulative Musculoskeletal Injuries

  • The Mining Program is doing work in this area that is highly relevant to mining and other industries. Research is in the high-priority areas of equipment and work design.

  • Interaction between the cumulative musculoskeletal research group and other NIOSH programs and divisions should be increased.

According to the National Institute for Occupational Safety and Health (NIOSH), musculoskeletal disorders (MSDs) include a group of conditions that involve the nerves, tendons, muscles, and supporting structures such as intervertebral disks. They represent a wide range of disorders that can differ in severity from mild, periodic symptoms to severe, chronic, and debilitating conditions. Work-related musculoskeletal disorders (WMSDs) arise from such risk factors as frequent or heavy lifting; pushing or pulling heavy objects; prolonged awkward postures; vibrations; and repetitive, forceful, or prolonged exertion of the hands. Examples of MSDs include low back pain, tendonitis, and carpal tunnel syndrome (NIOSH Facts, http://www.cdc.gov/niosh/muskdsfs.html). The solution to the WMSD problem is often sought through the application of ergonomics. Ergonomics is the science of fitting workplace conditions and job demands to the capabilities of workers.

Mining tasks and the mining environment are characterized by several unique factors. Major mining tasks involve handling either mining products or the mate-

1

Because the committee did not include an ergonomics expert, it commissioned a white paper from Dr. Barbara Silverstein, M.P.H., C.P.E. of the Washington State Department of Labor and Industries regarding the impact and relevance of ergonomics related research conducted within the NIOSH Mining Program. Her paper is included as Appendix C of this report and was carefully considered by the committee during the preparation of its review.



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Mining Safety and Health Research at NIOSH: Reviews of Research Programs of the National Institute for Occupational Safety and Health 10 Review of Research on the Reduction of Cumulative Musculoskeletal Injuries1 Key Findings and Recommendations for Research on Cumulative Musculoskeletal Injuries The Mining Program is doing work in this area that is highly relevant to mining and other industries. Research is in the high-priority areas of equipment and work design. Interaction between the cumulative musculoskeletal research group and other NIOSH programs and divisions should be increased. According to the National Institute for Occupational Safety and Health (NIOSH), musculoskeletal disorders (MSDs) include a group of conditions that involve the nerves, tendons, muscles, and supporting structures such as intervertebral disks. They represent a wide range of disorders that can differ in severity from mild, periodic symptoms to severe, chronic, and debilitating conditions. Work-related musculoskeletal disorders (WMSDs) arise from such risk factors as frequent or heavy lifting; pushing or pulling heavy objects; prolonged awkward postures; vibrations; and repetitive, forceful, or prolonged exertion of the hands. Examples of MSDs include low back pain, tendonitis, and carpal tunnel syndrome (NIOSH Facts, http://www.cdc.gov/niosh/muskdsfs.html). The solution to the WMSD problem is often sought through the application of ergonomics. Ergonomics is the science of fitting workplace conditions and job demands to the capabilities of workers. Mining tasks and the mining environment are characterized by several unique factors. Major mining tasks involve handling either mining products or the mate- 1 Because the committee did not include an ergonomics expert, it commissioned a white paper from Dr. Barbara Silverstein, M.P.H., C.P.E. of the Washington State Department of Labor and Industries regarding the impact and relevance of ergonomics related research conducted within the NIOSH Mining Program. Her paper is included as Appendix C of this report and was carefully considered by the committee during the preparation of its review.

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Mining Safety and Health Research at NIOSH: Reviews of Research Programs of the National Institute for Occupational Safety and Health TABLE 10-1 Illness and Non-Fatal Days Lost Data for Mine Operators from 1993 to 2002 Illness Data No. Percent NFDL Data No. Percent Cases 6,419   Cases 84,629   Repeated trauma disorders 3,314 52% Nature of injury     Part of body affected     Sprain, strain, ruptured disc 38,727 46% Wrist 1,445 23% Joints, tendon, muscle inflammation 421 1% Ears 1,154 18% Part of body affected     Back 430 7% Back 21,030 25% Knee 251 4% Knee 8,114 10% SOURCE: MSHA, 2006. rials associated with activities such as roof support, ventilation control, or power supply installation. Cutting, drilling, loading, and hauling equipment are a common part of miners’ work, but they are often done in confined places with poor clearances and on poor or uneven floors that create unfavorable conditions for body postures. Some working conditions create hazards associated with whole-body vibrations or slips and falls. Other environmental factors such as limited visibility, dust, noise, heat, and humidity, coupled with shift and extended hours, are also associated with mining injuries. Mining equipment operators often are exposed to heavy and repetitive jarring and jolting motions. Table 10-1 shows reported illness and non-fatal days lost (NFDL) injury data for mine operators between 1993 and 2002 (mill and office workers were not included). Repeated trauma disorders account for a majority of illnesses. In terms of parts of the body, ears are affected about 35 percent of the time, whereas wrist, back, and knee account for almost all other cases of repeated trauma (64 percent). Mining NFDL records indicate that nearly half of days lost were associated with sprains and strains, and approximately one third of days lost were associated with either back or knee injuries. Given that wrist, back, and knee injuries show up prominently in mining injury data, the work-related risk factors for these injuries need to be identified to reduce or eliminate them. STRATEGIC GOALS AND OBJECTIVES The reduction of repetitive or cumulative musculoskeletal injuries in mine workers as one of the Mining Program’s major strategic goals. The performance measure for achievement of this strategic goal is a 30 percent reduction in MSDs by 2014, from the baseline data of 2003. The two intermediate goals in this research area are summarized in Table 10-2. The committee recognizes that injury reduction research is enhanced by the increased application of human factors research

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Mining Safety and Health Research at NIOSH: Reviews of Research Programs of the National Institute for Occupational Safety and Health TABLE 10-2 Intermediate Goals and Performance Measures of the Reduction of Repetitive and Cumulative Musculoskeletal Injuries and Committee Comments Intermediate Goala Performance Measurea Committee Comments Quantify job demands and physical capabilities of miners to develop improved recommendations for work design This goal will be achieved by providing 10 improved designs and work practices for reducing musculoskeletal exposure in mining jobs by 2009 (1) The relationships between the goal and the performance measure is unclear. (2) Relationship between quantification of performance measure and performance measure itself is unclear Develop and field-test ergonomic interventions to reduce worker exposure to musculoskeletal risk factors This goal will be achieved by reducing the repetitive injury rate by 25% at test mine sites by 2009, using the 2003 rate as baseline Given data available on injury rates during the last decade, the performance measure chosen to meet this goal could be more ambitious aSOURCE: NIOSH, 2005a. results2 and ergonomic principles in mining. Achievement of performance measures is dependent on the acceptance of Mining Program recommendations regarding design, work practices, and ergonomic interventions. Table 10-3 compares illness and NFDL injury data for 1996 and 2005. The data provide insight into progress in the reduction of repeated trauma disorders and NFDL injuries. The number of unreported illnesses and injuries is not known, nor is it known how many incidents may be occurring prior to injury or illness inducing events. In view of the reduction in injuries noted in Table 10-3, performance measures for the strategic goal and the program’s second intermediate goal could be more challenging. REVIEW OF INPUTS Primary input comes from the Mine Safety and Health Administration (MSHA) surveillance data on injuries and lost work days. Other sources of input include 2 Ergonomics (or human factors) is the scientific discipline concerned with the understanding of interactions among humans and other elements of a system, and the profession that applies theory, principles, data, and other methods to design in order to optimize human well-being and overall system performance (http://www.iea.cc/ergonomics/).

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Mining Safety and Health Research at NIOSH: Reviews of Research Programs of the National Institute for Occupational Safety and Health TABLE 10-3 Comparison of Total Reported Illness and NFDL Injury Data for 1996 and 2005   1996 2005 Reduction (%) Illness Data       Number of illnesses 409 206 40 Repeated trauma disorders 232 155 33 Body part       Wrist 104 69 34 Back 41 16 70 Knee 22 16 27 NFDL Data       Number of NFDL 8,641 5,325 38 Sprain or strain 3,872 2,347 39 Joints and muscles 36 17 53 Back 2,106 1,037 52 Knee 770 573 26 Wrist 122 116 5 SOURCE: Vanessa A. Stewart, MSHA, personal communications to Raja V. Ramani on June 12, 2006, and June 14, 2006. mining companies, manufacturers, and worker unions. Specifically, NIOSH has worked with mining companies and equipment manufacturers on specific processes, procedures, and equipment development and demonstration projects. The Mining Program has also formed a partnership with a coal company to enhance the introduction of a process to reduce WMSD risk factors. Research on the reduction of cumulative musculoskeletal disorders is allocated approximately $2.0 million of total annual funding with discretionary funding of about $150,000. Currently, there are 20 full-time equivalents (FTEs) and four projects associated with this research area, which represents approximately 7 percent of the total Mining Program funding, 8 percent of the total FTEs, and 2 percent of total discretionary funding. Compared to 1998 statistics, these figures represent an increase of 67 percent in funding and 25 percent in FTEs. Expertise in the program includes physiology, bioengineering, mining, industrial and mechanical engineering, sociology and psychology, and industrial hygiene, though does not include expertise in epidemiology and cognitive ergonomics. Although the Mining Program describes a large overlap between its own interests and those of the NIOSH Musculoskeletal Research Program (NIOSH, 2006b), the level and nature of input from that program to the Mining Program could not be determined by the committee with the information received. The committee was not certain that such interactions filled gaps in expertise.

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Mining Safety and Health Research at NIOSH: Reviews of Research Programs of the National Institute for Occupational Safety and Health Several specialized facilities are available at the Pittsburgh and Spokane Research Laboratories for cumulative research. The facilities include equipment for motion analysis, shock tests, strength tests, simulation of mining tasks, and whole-body vibration. The attention paid to identify risk factors in the mining environment and mining work that cause cumulative musculoskeletal disorders is well deserved. The increase in funding and FTEs, while very modest, is to be commended. REVIEW OF ACTIVITIES Mining Program research activities to reduce WMSDs are aimed at designing tasks, tools, equipment, machine controls and displays, and training programs to be compatible with workers’ physical capabilities and limitations in the working environment. Properly designed tasks and equipment, in combination with appropriately trained workers, can reduce or eliminate overexertion, overuse of muscles, and bad posture at the worksite. Engineering control is the principal means of enacting improvements. The projects in this research area are concentrated on identifying and documenting risk factors for WMSDs and associated ergonomic issues in mining, as well as developing recommendations for reducing exposure to risk factors for cumulative injuries. Two lines of research can be seen in the cumulative injury program: the adaptation of off-the-shelf items for mining industry applications; and research on understanding the physiological and biomechanical aspects of mining work. Two major research activities of the last decade included improved seat design for shuttle cars in underground coal mines and a collaborative effort with a surface coal mining company for implementation of a process to reduce exposure to WMSD risk factors. The Mining Program’s role in this latter effort was limited to guiding and directing the coal company’s efforts in customizing and implementing an ergonomics process. Table 10-4 describes the four active projects being conducted within this research area. The following need to be considered to reduce the incidence of musculoskeletal disorders: (1) the task or work to be accomplished; (2) the individual(s) who will do the work; (3) the environment in which the work is accomplished (physical, chemical); (4) the technology and machines used in the performance of the task; and (5) the organization of the task, including such factors as hours of work, shift work, degree of social interaction, and level of supervision (Perez, 1999). The Mining Program incorporates these considerations into its activities. Laboratory and field studies are combined with physical and computer modeling to characterize and analyze WMSD risk factors associated with mining. Approaches to increase miner awareness of WMSD risk factors, and the introduction of ergonomic pro-

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Mining Safety and Health Research at NIOSH: Reviews of Research Programs of the National Institute for Occupational Safety and Health cesses into operations, have included the development of training programs and partnerships with mining companies and industry-wide organizations. While some project-specific suggestions regarding study design are given in Table 10-4, including suggestions regarding study methodology and implementation for a greater diversity in ergonomic intervention strategies, expertise beyond that currently available within the Mining Program may be required for implementation. Some mining tasks involve sedentary work, heavy lifting, a combination of environmental factors (e.g., noise, dust, heat, and humidity), or the effects of extended working hours (as a company practice or a result of overtime) and fatigue. All of these topics require research on their contributions to WMSDs. It is important to state that the cumulative injury program is a very small part of the Mining Program. While it may be possible to incorporate some of the topics identified here into the current program, additional resources would be required. REVIEW OF RESEARCH OUTPUTS The Mining Program reports 85 outputs from the MSD prevention research group between 1996 and 2005−approximately 6 percent of all Mining Program outputs. The outputs are mostly articles appearing in various journals, though a small number occur in other formats such as videos, software, training programs, checklists, and guidelines. Approximately 20 percent of these publications are related to risk factor case studies regarding machines associated with underground and surface mining unit operations and mines in general. Approximately 15 percent of outputs are associated with studies concerning biomechanics and body extremities. Approximately 33 percent of outputs are associated with strength testing, body postures, and human factors. Equipment design accounts for approximate 12 percent of the outputs. Case studies and descriptions of partnership results should be useful industry-wide. REVIEW OF TRANSFER ACTIVITIES The cumulative injuries prevention research area has utilized a number of means to reach stakeholders. In addition to the publications referred to above, the Mining Program web site presents information on several topics concerning ergonomics. Brief descriptions of general MSD issues are followed by more specific discussions topics, such as workplace and equipment design and engineering and administrative controls. References to several NIOSH publications are provided. Mining Program investigators have conducted training sessions at the request of mining companies and have conducted workshops at worker unions’ health and safety conferences. Direct contact with the users is likely to result in greater

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Mining Safety and Health Research at NIOSH: Reviews of Research Programs of the National Institute for Occupational Safety and Health TABLE 10-4 Cumulative Musculoskeletal Disorder Prevention Projects and Committee Assessment of Relevance and Impact Project Titlea Intermediate Goal Descriptiona Relevance Impact 1. Ergonomics Evaluation and Improvement of Mobile Equipment 1, 2 Reduction of musculoskeletal disorders among operators of mobile equipment in surface mining and construction operations. The tasks are to (1) conduct an epidemiologic survey of heavy-equipment operators through a work and health questionnaire, (2) characterize whole-body vibrations at the seat-driver interface and their effects on the operator’s postral stability in the seat, (3) estimate the landing force required to exit from mobile equipment, and (4) evaluate the ergonomic design of cabs and means of egress from and entry to the cabs While the comparison of pre-intervention conditions with post-intervention conditions is useful to document any improvements, establishment of a control and a non-control group would be desirable for the purposes of documenting the effectiveness of the intervention The project outputs should be useful to improve detection of MSD potential in equipment operators and to improve designs and procedures for cabs and means of egress and entry 2. Ergonomics Process Effectiveness in Mining 2 Development of recommendations for design of equipment and workplaces, and appropriate training modules, in partnership with two mining companies. Ergonomic processes will be implemented and evaluated in mines. Metrics will be developed to assess the growth and effectiveness of the process There is little question that partnering with specific mining companies is beneficial, but efforts should be directed to develop general guidelines and processes for the entire mining community The level of awareness of miners of the importance of ergonomics and the application of ergonomic processes in mining is expected to increase. An associated decrease in WMSD incident rates is also expected. These improvements will impact only those miner populations directly involved in investigations

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Mining Safety and Health Research at NIOSH: Reviews of Research Programs of the National Institute for Occupational Safety and Health 3. Reduce Injury and MSD Risk from Human-Machine Interactions 1 The reduction of WMSD risks associated with use of continuous miners, roof bolters, and load-haul-dump equipment in underground mining through improved design of machines and of operator tasks. Risks being studied include appendage-mining machine contact, stresses to the back associated with various kneeling and standing postures, and the effect of repetitive and forceful motions associated with equipment in motion. The study includes physical and computer modeling, motion analysis techniques, and operator task analysis This research is relevant and addresses many types of WMSDs associated with mining The study will lead to the development of a risk assessment methodology for equipment operators at underground mine working faces 4. Successful Aging for Miners Through Ergonomics (SAME) 1, 2 The project is aimed at all miners to ensure avoidance of workplace hazards associated with aging. Tasks identified include the development of (1) a training program for miners to increase their awareness of, and preparedness for, changes that occur with the aging process; (2) suggestions for boot designs, work procedures, and safer methods for ingress and egress from equipment to reduce slips and falls; and (3) a better tool to assess the risk of back injuries in miners and their engineering interventions The project addresses several tasks, not all related to aging. Given that the current median age of miners is approximately 46 years, it is appropriate to look at research to determine the avenues available for management to take these realities into account in the framework of organizational ergonomics This training program to make miners more aware of the impacts of aging on performance should be useful to the entire miner population aSOURCE: NIOSH, 2005a.

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Mining Safety and Health Research at NIOSH: Reviews of Research Programs of the National Institute for Occupational Safety and Health implementation of recommended practices than recommendations published in journals. Program collaboration with mining companies and equipment manufacturers has led to the introduction of ergonomic processes in the workplace (such as WMSD risk assessment tools) and the adoption by manufacturers of new equipment designs (e.g., dragline operator workstations, shuttle car operator seats). Videos on the latter products have also been made for use in training sessions and general distribution. Investigators in the MSD prevention research area of the Mining Program actively disseminate their research results to the community of fellow researchers and to the mining industry. Their efforts seem to be well-directed, based on research outcomes discussed in the next section. REVIEW OF INTERMEDIATE OUTCOMES AND CAUSAL IMPACT As a result of research within the Mining Program, there are a number of findings with regard to WMSD risk factors in the mining industry. NIOSH investigators note that miners spend a lot of time at work on their knees or in awkward, squatting positions, spawning a number of studies on knee injuries and the development of effective prevention strategies. Mining Program studies on the risk of WMSDs associated with mobile equipment, such as jarring, jolting, whole-body vibrations, and ingress and egress, have resulted in a number of improvements to equipment and work procedures. Implementation of ergonomic processes in several mines in different environments through partnerships with mine operators has led to the design of improved workstations and further development of training and evaluation programs. Joy Mining Machinery, a major supplier of underground coal mining machinery, reports the NIOSH-designed shuttle car seats are preferred by shuttle car operators over other available designs. The introduction of ergonomic processes (22 interventions in 3 years) resulting from the partnership with Bridger Coal Company has had many positive outcomes, including requests from other companies to introduce the processes in their own operations. According to the Mining Program (NIOSH, 2005a), 800 additional people from different organizations have been trained on risk factor awareness. The Bridger Coal/Mining Program partnership also resulted in the Mining Program’s decision to redesign the dragline operator workstation to better fit human limitations and task requirements. Given the limited number of underground and surface mining equipment manufacturers, the potential for transferring the shuttle car and dragline design improvements to other mining equipment in surface and underground mining is high.

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Mining Safety and Health Research at NIOSH: Reviews of Research Programs of the National Institute for Occupational Safety and Health REVIEW OF END OUTCOMES There are no clearly discernible end outcome data that can be directly associated with this research area. However, it is appropriate to conclude that the program is having positive impacts in the workplace in selected areas. The Mining Program informed the committee (NIOSH, 2005a), for example, that the percentage of employees reporting discomfort at the Bridger Coal Mine decreased by 15 percent over a 3-year period. It would be useful to collect and analyze injury experience data directly related to WMSDs on specific operations and tasks in order to develop a stronger association with specific interventions. A number of quantitative indicators attest to the adoption of NIOSH-designed shuttle car seats by manufacturers and mining companies. The number of replacement seats ordered for equipment currently in use underground and the number of shuttle cars sold with the new NIOSH-seat design are approximately 150 and 300, respectively. The WMSD injury rates of shuttle car operators should be tracked to study the effectiveness of the improved design. The cumulative musculoskeletal injury research area has generated a large amount of knowledge in the area of WMSDs in mining. The manner in which this knowledge can be put into practice by mining companies, equipment manufacturers, and training organizations has been demonstrated to a limited extent by the program itself. The outputs of this program are relevant to several other industries, particularly construction and agriculture, where the equipment and tasks are similar to those in mining. To ensure that these benefits accrue to the larger worker population, increased interaction between the Mining Program and other NIOSH programs should be explored. ASSESSMENT OF RELEVANCE AND IMPACT The present cumulative injury research program has concentrated on increasing awareness of ergonomic processes, development of better designs for mining equipment, and a greater understanding of mining tasks and their demands on the human body. From the discussion above, it is clear the program is doing work that is highly relevant to mining and other industries. Research is in the high-priority areas of equipment and work design. There is ample evidence of good engagement of mining companies, industry organizations, manufacturers, and union personnel in the definition of problems and the transfer of outputs. While there are no specific end outcome data to report, several major contributions have the potential to improve health and safety in the mining workplace.

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Mining Safety and Health Research at NIOSH: Reviews of Research Programs of the National Institute for Occupational Safety and Health PROGRESS IN TARGETING NEW RESEARCH Partnerships guide the direction of WMSD reduction research, indicating responsiveness to stakeholders. The committee, however, considers the Mining Program’s targeting of its WMSD reduction research to be largely reactive rather than proactive, resulting in accomplishments that are not necessarily applicable industry-wide. Since there is similarity in mining, civil engineering, and agricultural equipment, it would appear that there is a broader scope for the definition of WMSD issues and solutions through more rigorous and formal interactions between various NIOSH research programs and the MSD health effects group.