Annals of Occupational and Environmental Medicine最新文献

Background: Shift work that interferes with normal sleep patterns, is known to be a cause of sleep disturbance and has been studied through various occupational groups. However, it is not known which shift type is better for sleep health.

Methods: This study included 568 firefighters. Sleep quality was evaluated using Pittsburgh Sleep Quality Index. Sleep quality was categorized into 2 groups; good quality (≤ 5 points) and poor quality (≥ 6 points). Demographic variables, depression, anxiety, type of shift, and job were collected by self-reported questionnaires. The χ² test, t-test, and multiple logistic regression analysis were used to evaluate the effect of shift type on the sleep quality of firefighters.

Results: Three hundred thirty-seven firefighters (59.3%) have poor sleep quality. Compared to day workers, the odds ratios (ORs) of poor sleep quality were 2.169 (95% confidence interval: 1.137-4.134) in 6-day cycle, 2.161 (1.150-4.062) in 9-day cycle, 1.805 (1.087-2.997) in 21-day cycle, and 1.485 (0.718-3.069) in 3-day cycle. The ORs of poor sleep quality were 1.697(1.021-2.823) in fire suppression and 2.325 (1.213-4.455) in emergency medical service compared to administration.

Conclusions: All shift work type except for the 3-day cycle was associated with poor sleep quality compared to day work.

Background: Shift work is known to be associated with cardiovascular disease (CVD). It has been found that inflammatory reactions are involved in the onset and progression of CVD. Therefore, the purpose of this study was to investigate the association between shift work and inflammatory markers.

Methods: Among workers at an electronics manufacturing company, 2,329 workers who had a health checkup from January 2019 to December 2019 were targeted. The general and biochemical characteristics of daytime workers and shift workers were compared through the Independent-test and the χ² test. Through multiple linear regression analysis, the association with shift work and inflammatory markers was investigated. Through multiple logistic regression analysis, the association with shift work and high inflammatory markers.

Results: The mean total leukocytes, neutrophils, monocytes, lymphocytes of shift workers were significantly higher than those of daytime worker. The mean high-sensitivity C-reactive protein (hs-CRP) of shift workers was also higher than that of daytime workers but not significantly. In multiple linear regression, shift work was associated with increase of total leukocyte count (β = 0.367, p < 0.001) and hs-CRP (β = 0.140, p = 0.005) after adjusting for all variables. In multiple logistic regression analysis, shift work showed 2.27 times risk of high leukocyte count and 1.8 times risk of high hs-CRP level compared to daytime work after adjusting for all variables.

Conclusions: This study confirmed that shift work is associated with high inflammatory markers. Considering that high inflammatory markers is independent indicator of CVD, the association between shift work and high inflammatory markers may help to understand the CVD risk of shift workers.

Background: In Korea, few studies clarify insomnia and its association and absenteeism or presenteeism. Therefore, this study aims to examine the association between insomnia and absenteeism/presenteeism using the sixth Korean Working Conditions Survey.

Methods: Insomnia was evaluated by the Minimal Insomnia Symptoms Scale (MISS). Absenteeism and presenteeism were assessed by asking if the employee had experienced absence or working despite being ill for the prior 12 months at the point of the survey. Multiple logistic analyses were conducted to explore insomnia and its association with absenteeism and presenteeism.

Results: The odds ratios of insomnia for absenteeism and presenteeism were 3.48 (95% confidence interval [CI]: 2.76-4.39) and 3.68 (95% CI: 3.18-4.26) in the fully adjusted model. As the MISS scores increased, absenteeism and presenteeism showed the increasing trend that odd ratios increased accordingly from the first to the fourth quartile.

Conclusions: This study observed that insomnia was related to both absenteeism and presenteeism among Korean employees.

Background: Polycyclic aromatic hydrocarbons (PAHs) have become common pollutants with industrial development. Although the effect of exposure to PAHs on allergic disease in humans has been evaluated, evidence of an association is sparse. The association between PAH exposure and serum total immunoglobulin E (IgE) levels was evaluated in Korean adults.

Methods: In total, this study included 3,269 participants in the Third Korean National Environmental Health Survey (2015-2017). Four urinary PAH metabolites were used to assessed exposure to PAHs: 1-hydroxypyrene, 1-hydroxyphenanthrene, 2-naphthol, and 2-hydroxyfluorene. The analyses were performed on 3 cutoff levels (100 IU/mL, 114 IU/mL, and 150 IU/mL) set as the total IgE elevation. Prevalence of total IgE elevation by PAH exposure group and general characteristics (age, sex, BMI, smoking, alcohol drinking, and occupation) were analyzed using the Rao-Scott χ² test. Multiple logistic regression analyses were conducted to calculate adjusted odds ratios (ORs) for total IgE elevation by PAH exposure groups.

Results: Total IgE elevation differed significantly by age, sex, smoking status, alcohol drinking status, and occupation. For 2-hydroxyfluorene, the fourth quartile showed a significant association with IgE elevation compared to the first quartile in the analyses of cutoff-level 100 IU/mL (OR: 1.372, 95% confidence interval [CI]: 1.007-1.869) and 114 IU/mL (OR: 1.643, 95% CI: 1.167-2.312). In the analysis of cutoff-level 150 IU/mL, the adjusted ORs of the third and fourth quartile of 2-hydroxyfluorene were significantly higher than the first quartile (3rd quartile: OR: 1.478, 95% CI: 1.034-2.113; 4th quartile: OR: 1.715, 95% CI: 1.161-2.534). However, there were no significant positive associations for the other metabolites.

Conclusions: This study implied that PAHs exposure is associated with total IgE elevation in Korean adults. More research is needed to confirm the effect of exposure to PAHs on serum IgE and allergic diseases.

Background: This study aimed to investigate the association between lead exposure and serum gamma-glutamyl transpeptidase (γGT) levels as an oxidative stress marker in male steelworkers.

Methods: Data were collected during the annual health examination of workers in 2020. A total of 1,654 steelworkers were selected, and the variables for adjustment included the workers' general characteristics, lifestyle, and occupational characteristics. The association between the blood lead level (BLL) and serum γGT level was investigated by multiple linear and logistic regression analyses. The BLL and serum γGT values that were transformed into natural logarithms were used in multiple linear regression analysis, and the tertile of BLL was used in logistic regression analysis.

Results: The geometric mean of the participants' BLLs and serum γGT level was 1.36 μg/dL and 27.72 IU/L, respectively. Their BLLs differed depending on age, body mass index (BMI), smoking status, drinking status, shift work, and working period, while their serum γGT levels differed depending on age, BMI, smoking status, drinking status, physical activity, and working period. In multiple linear regression analysis, the difference in models 1, 2, and 3 was significant, obtaining 0.326, 0.176, and 0.172 (all: p < 0.001), respectively. In the multiple linear regression analysis stratified according to drinking status, BMI, and age, BLLs were positively associated with serum γGT levels. Regarding the logistic regression analysis, the odds ratio of the third BLL tertile in models 1, 2, and 3 (for having an elevated serum γGT level within the first tertile reference) was 2.74, 1.83, and 1.81, respectively.

Conclusions: BLL was positively associated with serum γGT levels in male steelworkers even at low lead concentrations (< 5 μg/dL).

Background: Recently, use of work-related communication technology-smartphones, tablets, and laptops-is increasing rapidly by development of technology with the coronavirus disease 2019 pandemic. Some studies have suggested that work-related communication technology has a significant link with work-family conflict (WFC) but these studies included only limited number of participants and lacked essential covariates. Therefore, this study analyzes this association using large representative data sample and selected waged workers who were married-couples with children.

Methods: This study was conducted based on data from the 6th Korean Working Conditions Surveys (KWCS). A total of 17,426 waged workers having a marriage partner and one or more children were selected. Logistic regression analysis was performed to determine whether WFC was associated with communication technology use. The odds ratios (ORs) for WFC were stratified by sex and working hours.

Results: In fully adjusted model, WFC was higher those who used communication technology outside regular working hours compared with those who did not use it (OR: 1.66; 95% confidence interval [CI]: 1.39-1.97). When stratified by sex and working hours, the effect was greater in women than in men (OR: 1.79; 95% CI: 1.42-2.26 vs. OR: 1.52; 95% CI: 1.17-1.97) and women who worked over 52 hours per week had the highest OR (3.40; 95% CI: 1.25-9.26).

Conclusions: This study revealed that the work-related communication technology use outside regular working hours was associated with WFC. The association were greater among those having longer working hours and female workers. These results suggest that appropriate policy should be implemented to reduce working hours and right to disconnect after work, particularly in female workers.

Background: Workers in logistics centers are always pressed for time to collect and pack products. They also participate in high-intensity manual labor in which various musculoskeletal hazards exist. In the case of logistic center labor, it is estimated that there is a high risk of presenteeism due to the above characteristics which can cause deterioration of workers' mental health. However, there is insufficient research on this topic.

Methods: Workers in a logistic center were surveyed using an Internet questionnaire. The survey items included demographic characteristics, labor intensity and work-related factors, and mental health aspects such as depression and anxiety. The survey was conducted for about a month from July 26, 2021 and a total of 353 people were analyzed. Through the χ² test and t-test, the characteristics of workers who experienced presenteeism were examined and the prevalence ratios (PRs) of depression and anxiety experiences were calculated by multivariable Poisson regression. Afterwards, stratification analysis considering gender, the type of contract, and labor intensity was implemented.

Results: In the group that experienced presenteeism, the number of working days per week was higher and fixed-term workers, high labor intensity, and sleep deprivation were more common. In the multi-Poisson regression analysis conducted by adjusting the demographic characteristics, working hours, and work-related factors, the PRs of depression and anxiety were 1.98 (95% confidence interval: 1.24-3.18) and 1.81 (1.22-2.68), respectively. In particular, the p-value for interactions was significant when stratified with the type of contract.

Conclusions: As a result of the study, presenteeism and mental health were associated in logistic center workers. To prevent mental health issues of logistic center workers, management of presenteeism is necessary and a prospective study is needed.

Background: Circadian rhythm disturbance caused by shift work has adverse effects on the metabolic homeostasis of the liver. Disruption of the metabolic homeostasis of the liver causes fat accumulation in the liver. The aim of this study was to investigate the correlation between shift work and non-alcoholic fatty liver disease (NAFLD) among male workers in the steel manufacturing industry of Korea.

Methods: Based on medical examination data collected in June 2020, 2,511 male subjects from one steel manufacturing company in Korea were selected in total. NAFLD was evaluated using abdominal ultrasound, which was performed by two experienced radiologists. The multinomial logistic regression analysis was performed by adjusting for age, physical activity, smoking history, alcohol consumption, body mass index, waist circumference, blood pressure, blood glucose, lipidemia, liver function test, employment duration, and hepatotoxic materials exposure status.

Results: Compared to daytime workers, the odds ratio (OR) of moderate-severe NAFLD in shift workers was 1.449 (95% confidence interval [CI], 1.028-2.043). Compared to daytime workers, the ORs of moderate-severe NAFLD were significantly higher for the group that engaged in total shift work for more than 20 years (OR, 2.285; 95% CI, 1.051-4.970), the group that was not allowed to sleep during night shift work (OR, 1.463; 95% CI, 1.030-2.078), and the group that consumed food during night shift work (OR, 1.580; 95% CI, 1.093-2.284).

Conclusions: There was a correlation between shift work and moderate-severe NAFLD in male steel manufacturing workers. There will be a need for more research related to the correlation of shift work with steatohepatitis and cirrhosis in the future.

Background: This study investigated the effect of dispatch frequency on blood cadmium levels and the effect of blood cadmium levels on hypertension in male firefighters in a metropolitan city.

Methods: We conducted a retrospective longitudinal study of male firefighters who completed the regular health checkups, including a health examination survey and blood cadmium measurements. We followed them for 3 years. To investigate the effect of dispatch frequency on blood cadmium levels and the effect of blood cadmium levels on hypertension, we estimated the short-term (model 1) and long-term (model 2) effects of exposure and hypothesized a reversed causal pathway model (model 3) for sensitivity analysis. Sequential conditional mean models were fitted using generalized estimating equations, and the odds ratios (ORs) and the respective 95% confidence intervals (CIs) were calculated for hypertension for log-transformed (base 2) blood cadmium levels and quartiles.

Results: Using the lowest category of dispatch frequency as a reference, we observed that the highest category showed an increase in blood cadmium levels of 1.879 (95% CI: 0.673, 3.086) μg/dL and 0.708 (95% CI: 0.023, 1.394) μg/dL in models 2 and 3, respectively. In addition, we observed that doubling the blood cadmium level significantly increased the odds of hypertension in model 1 (OR: 1.772; 95% CI: 1.046, 3.003) and model 3 (OR: 4.288; 95% CI: 1.110, 16.554). Using the lowest quartile of blood cadmium levels as a reference, the highest quartile showed increased odds of hypertension in model 1 (OR: 2.968; 95% CI: 1.121, 7.861) and model 3 (OR: 33.468; 95% CI: 1.881, 595.500).

Conclusions: We found that dispatch frequency may affect blood cadmium levels in male firefighters, and high blood cadmium levels may influence hypertension in a dose-response manner.

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 5^th 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.