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Background: The objective of this study was to investigate the relationship between irregular work schedules and sleep disturbance and compare the impacts of work schedule on sleep disturbance between occupational drivers and office workers. Methods: Using data from the 3rd and 4th Korean Working Conditions Survey, 3,070 occupational drivers and 9,898 office workers were included in this study. The subjects’ days of night work, evening work, and subjective complaints of sleep disturbance were investigated along with other covariates. Results: In the multivariate logistic regression analyses, occupational drivers (odds ratio [OR], 95% confidence interval [CI]: 1.51, 1.11–2.05), workers who were engaged in more night work (2.49, 1.84–3.38 for 1–15 days, and 3.80, 2.67–5.41 for 16–30 days) and evening work (2.22, 1.66–2.97 for 1–15 days, and 1.76, 1.26–2.45) were more likely to report sleep disturbance. Moreover, occupational driving showed significant interaction effects with both night and evening work on sleep disturbance, and therefore, showed higher ORs for sleep disturbance in the 16–30 days night (5.38, 3.40–8.52) and evening (3.13, 1.97–4.98) compared to no night and evening working office workers. Conclusions: Occupational drivers who are exposed to night work and evening work are at higher risks for sleep disturbance. Therefore, for the public and drivers’ safety, optimal work schedules for minimising sleep disturbance should be developed. [ABSTRACT FROM AUTHOR]

Introduction: The individual and combined effect of occupational noise and vibration exposures, on workers’ health has not been thoroughly investigated. In order to find better ways to prevent and manage workers’ headache, this study aimed to investigate the effects of occupational noise and vibration exposure on headache/eyestrain. Methods: We used data from the fourth Korean Working Condition Survey (2014). After applying inclusion and exclusion criteria, 25,751 workers were included. Occupational noise and vibration exposure and the prevalence of headache/eyestrain were investigated by self-reported survey. Chi-square tests were used to compare differences in baseline characteristics between the group with headache/eyestrain and the group without. Odds ratios and 95% confidence intervals were estimated using a logistic regression model adjusted for several covariates. Area under the receiver operating characteristics curve (AUROC) analysis was used to evaluate the effect of occupational noise and/or vibration exposure. Results: Among the 25,751 study subjects, 4,903 had experienced headache/eyestrain in the preceding year. There were significant differences in age, education level, household income, occupational classification, shift work, occupational vibration exposure, and occupational noise exposure between the two groups (all p<0.05). The odds ratios between each exposure and headache/eyestrain increased proportionally with the level of exposure, increasing from 1.08 to 1.26 with increasing vibration exposure, and from 1.25 to 1.41 with increasing noise exposure. According to the AUROC analysis, the predictive power of each exposure was significant, and increased when the two exposures were considered in combination. Discussion: The findings of this study show that both occupational noise and vibration exposures are associated with headache/eyestrain; noise exposure more strongly so. However, when the two exposures are considered in combination, the explanatory power for headache/eyestrain is increased. Therefore, efforts aimed at reducing and managing occupational noise and vibration exposure are crucial to maintaining workers’ health. [ABSTRACT FROM AUTHOR]

Osteoarthritis (OA) is a considerable health problem worldwide. It is known to be associated with certain occupational risk factors. We examined the prevalence rate of OA by occupational cluster. Data were collected from the Korea National Health and Nutrition Examination Surveys (2010–2013). The total number of unweighted sample size was 9,905 participants: 4,460 men and 5,445 women, and OA prevalence was 5.3% and 18.4% respectively. OA patients were defined as participants with knee/hip joint pain and radiographic change of knee/hip joint. Occupational type was classified as either white, pink, blue, or green collar based on the occupational characteristics following physical demand: white for manager and professionals; pink for clerks and service/sales workers; blue for craft/trade workers, machine operators and assemblers, and elementary manual workers; and green for agricultural/fishery workers. We calculated the odds ratios (ORs) and 95% confidence intervals (95% CI) for the odds of a participant’s having OA according to the occupational cluster, with gender stratification. The multiple logistic regression model showed that, compared to the white collar group, the ORs of the pink, blue, and green collar workers were 1.23 (95% CI 0.64–2.36), 1.85 (95% CI 1.18–2.88), and 2.91 (95% CI 1.86–4.54), respectively, in males, and 2.53 (95% CI 1.71–3.73), 2.86 (95% CI 1.94–4.21), and 3.90 (95% CI 2.60–5.83), respectively in females. The prevalence rate of OA was associated with the occupational cluster, in order from highest to lowest: green, blue, pink, and white collar. [ABSTRACT FROM AUTHOR]

Background: Long working hours are a worldwide problem and may increase the risk of various health issues. However, the health effects of long working hours on suicidal thoughts have not been frequently studied. Our goal was to investigate the relationship between long working hours and suicidal thoughts in the rapidly developing country of Korea. Methods: Data from 12,076 participants (7,164 men, 4,912 women) from the 4th and 5th Korean National Health and Nutrition Examination Surveys were used for the current analysis. Multivariate logistic regression models were used to estimate odds ratios and 95% confidence intervals for suicidal thoughts. Combined effects of long working hours and lower socioeconomic status or sleep disturbance were also estimated. Results: Compared to groups who worked less than 52 hours per week, odds ratios (95% confidence intervals) for suicidal thoughts in groups who worked 60 hours or more per week were 1.36 (1.09–1.70) for males and 1.38 (1.11–1.72) for females, even after controlling for household income, marital status, history of hypertension or diabetes mellitus, health-related behaviors, and past two weeks’ experience of injury, intoxication, or acute or chronic diseases, as well as type of work. The combined effects of long working hours with lower socioeconomic status, or with sleep disturbance, were also significantly higher compared to participants who worked less than 52 hours per week with higher socioeconomic status, or with 6–8 hours of nighttime sleep. Conclusion: In this study, long working hours were linked to suicidal thoughts for both genders. Additionally, the odds of those suicidal thoughts were higher for lower socioeconomic groups. To prevent adverse psychological health problems such as suicidal thoughts, a strategy regarding long working hours should be investigated. [ABSTRACT FROM AUTHOR]

Background: This study aimed to assess the association between oxidative damage markers and carotid artery intima-media thickness (CIMT) after controlling for conventional risk factors of atherosclerosis in multiple logistic regression models. Methods and Findings: Fifty-one case male participants (CIMT ≥ 0.9 mm) were enrolled during their visits to Korean Genomic Rural Cohort Study of Wonju centers between May 1 and August 31, 2011, along with 51 control participants (CIMT < 0.9 mm) selected using frequency matching by age group. The levels of oxidative damage markers, 8-hydroxy-2′-deoxyquuanosine (8-OHdG), malondialdehyde (MDA), and 8-iso-prostaglandin F2α (Isoprostane), were measured. Conditional logistic regression models were used to evaluate relative relationships between the oxidative damage markers and the risk of high CIMT. Results: The markers of oxidative lipid (Isoprostane and MDA) and DNA (8-OHdG) damage were associated with CIMT after controlling for the conventional risk factors, including age, low density lipoprotein, body mass index, smoking history, alcohol consumption, and metabolic syndrome (ORs [95% CI] for Isoprostane: 3rd tertile, 8.47 [2.59-27.67]; for MDA: 3rd tertile, 8.47 [2.59-27.67]; for 8-OHdG: 3rd tertile, 5.58 [1.79-17.33]). When all the oxidative damage markers were incorporated in the same logistic regression model, only Isoprostanewas significantly related to CIMT (OR [95% CI]: 4.22 [1.31-13.53] in 2nd tertile and 14.21 [3.34-60.56] in 3rd tertile). Conclusions: In this nested case-control study, the oxidative damage markers of lipid and DNA were associated with CIMT even after controlling for the conventional risk factors of cardiovascular diseases. [ABSTRACT FROM AUTHOR]

Background: Noise, or undesirable sound, is one of the most common environmental stressors, and it can cause various health effects. Beyond the auditory consequences of occupational noise exposure, extra-auditory effects such as psychological problems have also been found. The aim of the current study is to elucidate the association between occupational noise annoyance and psychological symptoms, including symptoms of depression and suicidal ideation. Methods: A total of 10,020 participants (5,410 men and 4,610 women) were included in the current analysis, using data from the fourth Korean National Health and Nutrition Examination Survey (KNHANES). Self-report questionnaires were used to assess noise annoyance levels, depressive symptoms, and suicidal ideation. Odds ratios (ORs) and 95% confidence intervals (95% CIs) for psychosocial symptoms were calculated using multiple logistic regression models. Results: Compared to the no noise annoyance group, ORs (95% CI) of the severe annoyance groups were 1.58 (1.12–2.23) and 1.76 (1.29–2.40) in men and 1.49 (1.05–2.11) and 1.41 (1.01–1.97) in women for depressive symptoms and suicidal ideation, respectively. The ORs (95% CI) for severe noise annoyance in those with less than five hours of sleep were 2.95 (1.46–5.96) and 2.05 (1.01–4.16) in men and women, respectively, compared with those with no noise annoyance and a sleep time of more than five hours. Conclusion: Our study shows that occupational noise annoyance is significantly related to mental health, including depressive symptoms and suicidal ideation after controlling for individual and socio-demographic characteristics even with gender stratification. However, prospective studies with quantified noise exposure assessment were needed to elucidate the causality on the association between noise annoyance and psychological symptoms. [ABSTRACT FROM AUTHOR]

Background: Despite epidemiological evidences of relationship between poor lung function and atherosclerosis, the relationship between poor lung function and microalbuminuria (MAU), an early surrogate marker of both kidney damage and atherosclerosis, is not well understood. Hence, we plan to investigate the relationship between poor lung function and MAU using multivariate models to adjust for other atherogenic risk factors. Methods: We used data from the 5th Korean National Health and Nutrition Examination Survey. Poor lung function is determined by spirometric measurement, primarily through estimation of the forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1). Declines in the percent predicted FVC (<80%) and in the FEV1/FVC ratio (<0.7) are defined as restrictive and obstructive patterns, respectively. Urine albumin to urine creatinine levels ratio (UACR) were measured in spot urine samples. MAU was defined as UACR >30 mg/g. Results: Inverse relationship was observed between lung function and UACR. In an age-adjusted regression model, the regression coefficient (B) of 10% lower FVC was 11.09 in men (P = 0.002), which remained significant after adjustment for SBP, FBG, triglyceride level, BMI, smoking history, and heavy alcohol consumption (B = 7.52, P = 0.043). When the restrictive pattern was compared to the normal pattern, the odds ratios (OR) (95% confidence interval, 95%CI) for MAU were 1.90 (1.32–2.72) in men, after adjustment for age, hypertension, diabetes mellitus, triglyceride level, obesity, smoking history, physical activity, and heavy alcohol consumption. Conclusions: Our study, the first investigation in Asia, demonstrated that the restrictive pattern is related to MAU in men. Furthermore, there was linear relationship between lower FVC and UACR. Thus, our current study suggests that poor lung function, particularly the restrictive pattern, is related to kidney damage as well as atherosclerosis. [ABSTRACT FROM AUTHOR]

Background: Foundry work is associated with serious occupational hazards. Although several studies have investigated the health risks associated with foundry work, the results of these studies have been inconsistent with the exception of an increased lung cancer risk. The current study evaluated the mortality of Korean foundry workers due to malignant and non-malignant diseases. Methods: This study is part of an ongoing investigation of Korean foundry workers. To date, we have observed more than 150,000 person-years in male foundry production workers. In the current study, we stratified mortality ratios by the following job categories: melting-pouring, molding-coremaking, fettling, and uncategorized production work. We calculated standard mortality ratios (SMR) of foundry workers compare to general Korean men and relative risk (RR) of mortality of foundry production workers reference to non-production worker, respectively. Results: Korean foundry production workers had a significantly higher risk of mortality due to malignant disease, including stomach (RR: 3.96; 95% CI: 1.41–11.06) and lung cancer (RR: 2.08; 95% CI: 1.01–4.30), compared with non-production workers. High mortality ratios were also observed for non-malignant diseases, including diseases of the circulatory (RR: 1.92; 95% CI: 1.18–3.14), respiratory (RR: 1.71; 95% CI: 1.52–21.42 for uncategorized production worker), and digestive (RR: 2.27; 95% CI: 1.22–4.24) systems, as well as for injuries (RR: 2.36; 95% CI: 1.52–3.66) including suicide (RR: 3.64; 95% CI: 1.32–10.01). Conclusion: This study suggests that foundry production work significantly increases the risk of mortality due to some kinds of malignant and non-malignant diseases compared with non-production work. [ABSTRACT FROM AUTHOR]

Background: This study evaluated the relation between adiponectin and atherosclerosis in both genders, and investigated whether adiponectin provides useful additional information for assessing the risk of atherosclerosis. Methods: We measured serum adiponectin levels and other cardiovascular risk factors in 1033 subjects (454 men, 579 women) from the Korean Genomic Rural Cohort study. Carotid intima–media-thickness (CIMT) was used as measure of atherosclerosis. Odds ratios (ORs) with 95% confidence intervals (95% CI) were calculated using multiple logistic regression, and receiver operating characteristic curves (ROC), the category-free net reclassification improvement (NRI) and integrated discrimination improvement (IDI) were calculated. Results: After adjustment for conventional cardiovascular risk factors, such as age, waist circumference, smoking history, low-density and high-density lipoprotein cholesterol, triglycerides, systolic blood pressure and insulin resistance, the ORs (95%CI) of the third tertile adiponectin group were 0.42 (0.25–0.72) in men and 0.47 (0.29–0.75) in women. The area under the curve (AUC) on the ROC analysis increased significantly by 0.025 in men and 0.022 in women when adiponectin was added to the logistic model of conventional cardiovascular risk factors (AUC in men: 0.655 to 0.680, p = 0.038; AUC in women: 0.654 to 0.676, p = 0.041). The NRI was 0.32 (95%CI: 0.13–0.50, p<0.001), and the IDI was 0.03 (95%CI: 0.01–0.04, p<0.001) for men. For women, the category-free NRI was 0.18 (95%CI: 0.02–0.34, p = 0.031) and the IDI was 0.003 (95%CI: −0.002–0.008, p = 0.189). Conclusion: Adiponectin and atherosclerosis were significantly related in both genders, and these relationships were independent of conventional cardiovascular risk factors. Furthermore, adiponectin provided additional information to conventional cardiovascular risk factors regarding the risk of atherosclerosis. [ABSTRACT FROM AUTHOR]