We conducted this experimental study to estimate a risk of a high-risk group of low back pain (LBP) membership in workers who perform the manual material handling (MMH) tasks in an actual workplace setting.

The subjects include healthy workers who were engaged in 12 MMH tasks at 6 manufacturing companies. We assessed the dynamic motion of trunk or lumbar spine using an industrial lumbar motion monitor (BioDynamics Laboratory of Ohio State University). The subjects were evaluated for the age, gender, years of working and anthropometric measurements (e.g., height, weight, shoulder height, elbow height, iliac height, leg length, trunk length, trunk circumference, iliac width, iliac depth, xiphoid width and xiphoid depth). Moreover, they were also evaluated for a risk of a high-risk group of LBP membership based on lift frequency, average twisting velocity, maximum moment, maximum sagittal flexion and maximum lateral velocity.

The subjects who were engaged in a packaging at a detergent manufacturing company are at the greatest risk of LBP (63.76%). This was followed by packaging at a leather product manufacturing company (57.06%), packaging at a non-metallic casting material manufacturing company (57.03%), manual injection at a non-metallic casting material manufacturing company (52.00%), toggling at a leather product manufacturing company (46.09%), non-metallic casting material manufacturing company (42.88%), rolling at a non-metallic mineral product manufacturing company (42.12%), shooting at a non-metallic casting material manufacturing company (40.99%), vacuum processes at a leather product manufacturing company (35.00%), looping at a general industrial machinery manufacturing company (33.93%), setting at a leather product manufacturing company (30.22%) and packaging at a general metal product manufacturing company (22.02%).

Our approach indicates that there is a risk of a high-risk group of LBP membership in workers who perform the MMH tasks.

We examined factors related to depressive symptoms in Korean self-employed workers.

This secondary analysis examined data of 14,454 self-employed individuals from the fifth Korean Working Conditions Survey (2017). Multiple logistic regression analysis was used to assess the relationship of depressive symptoms with different variables.

Self-employed workers who had a good work-life balance, a good subjective health, and worked 40 to 48 hours or 48 to 60 hours/week were less likely to report depressive symptoms (all p < 0.05). However, those who always interacted with angry clients, had severe exposure to ergonomic risk factors, and were exposed to moderate or severe abusive behaviors were more likely to report depressive symptoms (all p < 0.05). Age, gender, weekly work days, and working at very fast speed were unrelated to depressive symptoms.

Several factors known to be related to depressive symptoms do not lead to depression in self-employed individuals. Different interventions may therefore be needed to prevent depression in self-employed workers.