Assessment of ergonomic risk factors among hand-made shoes workers in Tabriz, northwestern Iran

The production of hand-made shoes exposes workers to ergonomic stressors that may result in musculoskeletal disorders of the upper extremities. The purpose of this study was to assess the level of ergonomic risk factors in hand-made shoes workers.

This cross-sectional study was conducted on 218 hand-made shoes workers employed in small traditional workshops in Tabriz, northwestern Iran. The Nordic questionnaire was used to record the symptoms of musculoskeletal disorders.  Revise strain index (RSI) and the ACGIH hand activity level threshold limit value (HAL-TLV) were applied to assess the risk level using videotaping and direct observation of work cycles.  For data analysis, the independent t-test, Spearman correlation, and Kappa statistics were employed.

The most prevalent symptom was observed in the neck of the workers (90.7-98.4%). The mean score of RSI and HAL-TLV exceeded the safe level (RSI>10 and HAL-TLV>0.78) in upper makers and shoemakers but not in the sewing operators. The mean scores of the right hands of upper makers and shoemakers were statistically different and greater than the score of the left hand. The EM and IM were identified as the most contributing multipliers of RSI. The scores of RSI and HAL-TLV were highly correlated and classified workers with good agreement.

According to RSI and HAL-TLV, the biomechanical stress in the hands of upper makers and shoemakers should be reduced. Ergonomic interventions are proposed to decrease the repetitive actions and the intensity of forces during upper making and shoemaking tasks.