Risk assessment in manual lifting and low back pain in manufacturing workers

Introduction
Low back pain is a frequent symptom in the manufacturing workers and impacts not only their health but also companies productivity. This study’s objective was to evaluate, in a new manufacturing factory, the association between the ergonomic risks related to manual lifting operations and presence of low back pain in the exposed workers.

Methods
It was a cross-sectional study. A group of 17 production lines were evaluated and 23 workers from those lines participated in the study. To assess the lifting conditions the NIOSH equation was used and a questionnaire to obtained personal and health information from the workers was applied. 

Results
From the evaluated production lines, 8.8% had a high risk level and 32.3% a medium risk level. About low back pain prevalence in the exposed workers, the percentage of workers that referred clinical symptoms was 35.3. The probability of having back pain was 3.6 and 4.4 times higher in workers in medium and high risk positions in comparison with those in low risk positions. The trend of increment of back pain risk with an increment of position’s risk was significant (p=0.013). 

Discussion
Manual lifting represented a risk of muscle skeletal disorders presence, mainly low back pain. This research showed that the evaluated level of risk using the NIOSH equation it was a good predictor of low back pain presence.