A Field Assessment On The Risk Factors Of Occupational Musculoskeletal Disorders

IntroductionWith the development of science and technology, traditional gradually under control of occupational diseases, occupational musculoskeletal disorders (Occupational musculoskeletal disorders, OMSD) get more and more cause for concern. In the workplace in addition to chemical, physical and biological factors, occupational hazards, but there are many other adverse factors or load, such as: hand-moving lift (Manual lifting), static work, non-physical labor positions, and even irrational labor organization. These factors can be analyzed and evaluated on ergonomics in the known adverse ergonomic factors. Occupational incidence of musculoskeletal disorders in the workplace is largely poor ergonomic factors. The ergonomic factors on human health are comprehensive, interaction. Moreover, exposure to such factors will not only lead to musculoskeletal disorders, affecting work efficiency, and even lead to accidents. Therefore, the correct and comprehensive assessment of the work load of workers or risk factors in reducing the incidence of musculoskeletal disorders, improve efficiency, reduce security incidents are positive. Load factors of labor abroad or have the assessment of years of history, a variety of methods. These methods include self-report methods, questionnaires, observation, direct measurement method, can be divided into: subjective methods and objective methods, and in between the observation. Currently, there are no suitable for field use, the more systematic assessment method. Therefore, in the first part ,we refer to, of Surrey University, UK Research Centre Rohen exposure test for the rapid development (Quick Exposure Check), in a shipyard and automobile factories and the labor load on workers to observe and evaluate the relevant factors, the purpose was to examine QEC Method in the actual production work in usability. The second part we uses EMG (electromyography, EMG) and ECG to determine such a direct measurement and evaluation of workers labor in the production of the load operation. The adverse ergonomic factors or the level of work load in contact with the previous musculoskeletal disorders in the factory the results of epidemiological survey to compare. Musculoskeletal disorders to the risk factors for the field evaluation of the methods applied.PartⅠ. Application of QEC method to evaluate exposure to risk factors for musculoskeletal disordersObjectiveEvaluation of QEC in the risk factors of musculoskeletal disorders in the use of field studiesMethodsIn a shipyard and automobile manufacturing, application QEC 162 different types of workers observed the operation and evaluate the work load. According to the survey to assess the reliability of QEC and QEC scores of labor load, the level of exposure risk factors for musculoskeletal disorders and the relationship between workers.ResultsQEC score between observer reliability ICC was 0.71-1, reliability between the different observation spearman coefficients 0.61-1. In the shipyard, the different types of risk factor exposure levels (QEC score) for the plumber> assemblers > Welders; in the automobile factory as welders> stamping work> machining> Casters> assemblers. Motor system for maximum exposure was the severity of back and neck, followed by the shoulder and wrist. QEC scores of body parts related to its analysis showed that the annual prevalence rate in the shoulder and the correlation coefficient r2 = 0.670, wrist, r2 = 0.740, waist (static operation) r2 = 0.958, P all <0.05, and in the lumbar (dynamic operations) r2 =- 0.193, P> 0.05. Shows the level of their exposure to these areas is closely related to disease incidence. logistic analysis showed that: In addition to the static medium level results back and musculoskeletal disorders were negatively correlated, other contacts with the appropriate level of severity the prevalence of musculoskeletal disorders were positively correlated, with statistical significance (P <0.05).ConclusionQEC can be used for shipbuilding and automobile manufacturing workers in contact with risk factors for musculoskeletal disorders of the site evaluation, the method has some credibility. Quick exposure check evaluation of exposure levels and the corresponding prevalence of musculoskeletal disorders are closely related, confirming QEC site load in our evaluation of reliability. Neck loads in different types of work are very high, and no difference between the different types of work. Studies have shown that a certain degree of dynamic load waist protective factors for the musculoskeletal disorders, static load proved to be risk factors for musculoskeletal disorders.PartⅡ. Field measurement of work load with electromyographyObjective According to EMG measured by on-site indicators (MVE%) to reflect the work load, and to explore whether it related with the etiology of occupational musculoskeletal disorders。MethodsIn the shipyards and car factories'main type of work, workers were randomly selected as the test object 4-5. Shipyard main types include: welders, electricians, assemblers, plumbers and designers. Automobile factory: assemblers, Casters and machining. In normal operation, through the surface EMG telemetry records left and right trapezius and 3 of the lumbar spine (L3) levels of left and right side Para spinal muscle EMG. At the same time, the use of long-term ECG records heart rate instruments. Maximum voluntary contraction of workers when the EMG signal as a reference, the percentage of maximal voluntary contraction electromyography obtained (the percent of maximal voluntary electrical activation, MVE%), said time domain index of EMG amplitude. MVE% time domain Comparative analysis of the different types of muscle EMG difference between the values of MVE% of workers tested the relationship between chronic musculoskeletal disordersResultsIn the shipyard, the workers of different types of heart rate in order were: plumber> Welders> assemblers > Electrician >designer; working in the automobile factory for stamping> Casters > machining > assemblers, including plumber heart rate reached 107 beats/min, the heart rate of stamping reached 108 beats/min.. Different types of task the right trapezius muscle MVE% was different. At the shipyard workers MVE% from high to low were: plumber>Electrician>Welders>assemblers>designer. Automobile Manufacturer: Casters > Machining> assemblers; the right L3 erector spinae level MVE% different types of workers, from high to low: Shipyard were: assemblers> Welders> plumber> Designer> Electrician; its Automobile Manufacturer: Casters > Machining > assemblers. Among them, the back generally vertical ridge above the trapezius muscle MVE%, the difference between left and right side muscles were statistically significant. Waist MVE% difference between the different types of work was significant, and higher than 40%. Surface EMG and time domain correlation between musculoskeletal disorders showed: The prevalence of musculoskeletal disorders and MVE% incidence rate was positively correlated, and the muscle and musculoskeletal disorders MVE% dose-response relationship between statistically significant (p <0.05); In contrast, the muscle between the RMS and musculoskeletal disorders related analysis: In addition to the right L3 erector spinae and the prevalence rate was statistically significant correlation between, the other three muscles and the difference between the prevalence of no statistical significance. The lowest heart rate control designer L3 signals left and right side paraspinal muscle was slightly higher than the shipyard electrician; left and right trapezius muscle above the car factory assemblers.ConclusionBoth EMG MVE%, heart rate (beats / min) measured results can be reflect to the workload of different types, but there are different level of order, respectively, reflecting the different parts of the body when in the labor load and stress. EMG MVE% and the prevalence of musculoskeletal disorders were closely related, suggesting that high local muscle stress and the etiology of these disorders linked. Also, confirmed the surface electromyography for use in the field the credibility and reliability.