Association between working evening shifts and mental health among Korean employees: data from the 5th Korean Working Conditions Survey.

Background: Many studies have been conducted to investigate the harmful effect of shift work on physical and mental health. Although, by definition, "working evening shift" is included in the scope of shift work, most related studies conducted thus far have focused on working night shifts, overtime work, or different types of shift work, with little research effort dedicated to "working evening shifts." Therefore, to fill this research gap, we investigated the effect of working evening shifts on workers' mental health. Methods: The participants of this study were 16,692 employees of the 50,205 that participated in the 5th wave of the Korean Working Conditions Survey. We performed χ2 test and logistic regression analysis to analyze the effects of independent variables on health problems and calculated odds ratios and 95% confidence intervals (CIs). Results: In the logistic regression analysis adjusted for sociodemographic characteristics, health-related factors, and work-related characteristics, employees who worked evening shifts showed higher levels of depression and anxiety compared to those that did not. In particular, the adjusted odds ratios of the group working evening shifts between one and nine times a month were the highest with 2.723 (95% CI: 2.014-3.682) for depression, 3.294 (95% CI: 2.547-4.259) for anxiety. Conclusions: The results of our study suggest that working evening shifts has a negative effect on employees' mental health. This trend decreased with an increase in the monthly frequency of evening work.

A pilot study to assess a risk of a high-risk group of low back pain membership in workers who perform the manual material handling tasks.

BACKGROUND: 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. METHODS: 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. RESULTS: 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%). CONCLUSIONS: Our approach indicates that there is a risk of a high-risk group of LBP membership in workers who perform the MMH tasks.