Workload assessment of workers in the assembly line of a manufacturing industry and its Correlation with prevalence of wrist disorders

Background and aim: Musculoskeletal disorders in assembly line, is caused by poor physical conditions, repetitive motion, and psychological factors. This study aims to evaluate the workload and its association with the prevalence of wrist disorders were carried out in the assembly workers of a manufacturing industry. Methods: In this cross-sectional study was conducted among 120 female workers employed, the mental workload, physical workload and prevalence of wrist disorders were evaluated using the NASA-TLX, the OCRA method and the Nordic wrist and hand scan questionnaire respectively. Results: The NASA-TLX showed that the physical demands and effort with mean scores of 78.79 and 78.37 were respectively the most important subjective mental workload (SMWL) scale. Also the results on the basis of the OCRA risk level showed that the highest right-hand risk was at risk level 3 and the highest left-hand risk was at risk 1 .The Statistical analysis showed that OCRA risk levels and mean scale physical demands and effort were significantly higher in those with wrist pain than those with without pain (p <0.05).There was a direct correlation between the severity of the wrist pain with the OCRA risk index in both hands (P =0.001) and the total score of NASA (r = 0.232, p <0.05). Conclusion: It was revealed that mental load was high in assembly lines of the manufacturing industry and this result was also confirmed by physical evaluation. This study indicate the overall score of SMWL can affect the incidence of MSDs. That is why mental workload should be considered as a risk factor for MSDs.