Kidneys are organs having a biological clock, and it is well known that the disruption of the circadian rhythm increases the risk of chronic kidney disease (CKD), including the decline of renal and proteinuria. Because shift work causes circadian disruption, it can directly or indirectly affect the incidence of chronic kidney disease. Therefore, the purpose of this study was to investigate the association between shift work and chronic kidney disease using a Korean representative survey dataset.
This study was comprised of 3504 manual labor workers over 20 years of age from data from the fifth and sixth Korea National Health and Nutrition Examination Survey (2011–2014). The work schedules were classified into two types: day work and shift work. The estimated glomerular filtration rate, which is the ideal marker of renal function, was estimated according to the Chronic Kidney Disease Epidemiology Collaboration creatinine equation, and chronic kidney disease was defined as urinary albumin to a creatinine ratio equal to or high than 30 mg/g and/or estimated glomerular filtration rate lower than 60 mL/min/1.73 m2. The cross-tabulation analysis and multivariate logistic regression analysis were performed to confirm the association between shift work and chronic kidney disease stratified by gender.
The risk of CKD showed a significant increase (odds ratio = 2.04, 95% confidence interval = 1.22, 3.41) in the female worker group. The same results were obtained after all confounding variables were adjusted (odds ratio = 2.34, 95% confidence interval = 1.35, 4.07). However, the results of the male worker group were not significant.
In this study using nationally representative surveys, we found that the risk of CKD was higher female workers and shift work. Future prospective cohort studies will be needed to clarify the causal relationship between shift work and CKD.
Citations


It has been reported that long working hours are hazardous to the workers’ health. Especially, work-related musculoskeletal disorders (WMSDs) have been considered as one of the significant health issues in workplace. The objective of this study was to identify the association between long working hours and work-related musculoskeletal symptoms.
The analysis was conducted using data from the Fourth Korean Working Conditions Survey (KWCS). Subjects of this study were 24,783 wage workers and divided into three groups according to the weekly working hours, which were ≤ 40, 41–52 and > 52 h. The relationship between long working hours and work-related musculoskeletal symptoms was analyzed by multivariate logistic regression method after adjusting for general, occupational characteristics including specific working motions or postures and psychosocial factors.
Approximately 18.4% of subjects worked more than 52 h per week and 26.4 and 16.4% of male subjects and 33.0 and 23.4% of female subjects experienced work-related upper and lower limb pains, respectively, over the last 12 months. Moreover, the prevalence of upper and lower limb pain was increased in both genders as the weekly working hours increased. The odds ratios (ORs) of upper limb pain for those working 41–52 h and more than 52 h per week when adjusted for general, occupational characteristics including specific motions or postures and psychosocial factors were 1.36 and 1.40 for male workers and 1.26 and 1.66 for female workers compared to the reference group, respectively. Furthermore, ORs of lower limb pain for the same weekly working hour groups were 1.26 and 1.47 for male workers and 1.20 and 1.47 for female workers, respectively.
Long working hours were significantly related to work-related musculoskeletal symptoms in Korean wage workers and appropriate interventions should be implemented to reduce long working hours that can negatively affect workers’ health.
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Normobaric (NH) and hypobaric hypoxia (HH) are associated with acute mountain sickness (AMS) and cognitive dysfunction. Only few variables, like heart-rate-variability, are correlated with AMS. However, prediction of AMS remains difficult. We therefore designed an expedition-study with healthy volunteers in NH/HH to investigate additional non-invasive hemodynamic variables associated with AMS.
Eleven healthy subjects were examined in NH (FiO2 13.1%; equivalent of 3.883 m a.s.l; duration 4 h) and HH (3.883 m a.s.l.; duration 24 h) before and after an exercise of 120 min. Changes in parameters of electrical cardiometry (cardiac index (CI), left-ventricular ejection time (LVET), stroke volume (SV), index of contractility (ICON)), near-infrared spectroscopy (cerebral oxygenation, rScO2), Lake-Louise-Score (LLS) and cognitive function tests were assessed. One-Way-ANOVA, Wilcoxon matched-pairs test, Spearman’s-correlation-analysis and Student’s t-test were performed.
HH increased heart rate (HR), mean arterial pressure (MAP) and CI and decreased LVET, SV and ICON, whereas NH increased HR and decreased LVET. In both NH and HH cerebral oxygenation decreased and LLS increased significantly. After 24 h in HH, 6 of 11 subjects (54.6%) developed AMS. LLS remained increased until 24 h in HH, whereas cognitive function remained unaltered. In HH, HR and LLS were inversely correlated (
Both acute NH and HH altered hemodynamic and cerebral oxygenation and induced AMS. Subjects, who adapted their CI had higher rScO2 and lower LLS. Furthermore, rScO2 after exercise under normobaric conditions was associated with AMS at high altitudes.
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The International Agency for Research on Cancer (IARC) defined that asbestos is a group 1 substance that causes lung cancer, mesothelioma (pleura and peritoneum), laryngeal cancer, and ovarian cancer in humans. Many studies on lung cancer, and mesothelioma caused by asbestos exposure have been conducted, but there was no case report of ovarian cancer due to asbestos exposure in Korea. We describe a case of ovarian cancer caused by asbestos exposure in a worker who worked at an asbestos textile factory for 3 years and 7 months in the late 1970s.
A 57-year-old woman visited the hospital because she had difficulty urinating. Ovarian cancer was suspected in radiologic examination, and exploratory laparotomy was performed. She was diagnosed with epithelial ovarian cancer. The patient did not undergo postoperative chemotherapy and recovered. She joined the asbestos factory in March 1976 and engaged in asbestos textile twisting and spinning for 1 year, 2 years and 7 months respectively. In addition, she lived near the asbestos factory for more than 20 years. There was no other specificity or family history.
Considering the patient’s occupational and environmental history, it is estimated that she had been exposed to asbestos significantly, so we determined that ovarian cancer in the patient is highly correlated with the occupational exposure of asbestos and environmental exposure is a possible cause as well. Social devices are needed to prevent further exposure to asbestos. It is also necessary to recognize that ovarian cancer can occur in workers who have previously been exposed to asbestos, and the education and social compensation for those workers are needed.
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Research on carcinogens causing occupational cancer has been updated. Further, social interest in occupational cancer has increased. In addition, the standard for recognizing cancer as a work-related disease has also been revised. The present study aims to describe the distribution of occupational cancer claims or its approval rate and their association with work-related variables.
We analyzed 1299 claim cases for occupational cancer from 2010 to 2016 provided by the Korea Workers’ Compensation and Welfare Service (KCOMWEL). The status of approval rate was shown by year, sex, industry, occupation, age of diagnosis, duration from employment to diagnosis, and cancer site.
The approval rate was 39.0% from 2010 to 2016 and tended to increase annually since 2011. Both the number of claims and the approval rate were higher in men. Mining and quarrying showed the highest approval rate (78.4%). The approval rates by age of diagnosis and duration from employment to diagnosis increased as the time periods increased. Respiratory organ had the highest number of claims and the highest approval rate by cancer site.
The approval rate of occupational cancer has shown an increasing trend since 2011. The increase of occupational carcinogens and cancer sites and the improvement of social awareness about occupational cancer could have resulted in this trend. The present study provides unique, and the latest and most accurate findings on occupational cancer data of recent 7 years that could be helpful to researchers or policy makers on occupational cancer.
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This study was conducted to identify the sleep status of daytime workers who do not work in shifts. This study analyzed factors affecting sleep duration and sleep quality.
This study was conducted on 1171 daytime workers at a manufacturing workshop. We used a self-administered questionnaire to investigate demographic variables, work type, working period, musculoskeletal symptoms and the Pittsburgh Sleep Quality Index to assess sleep. Regular health checkup was conducted for the worker’s clinical examination.
The mean sleep duration was 6.36 h and the mean score on the Pittsburgh Sleep Quality Index was 4.46. Work type and obesity were related to sleep duration. Age, obesity and musculoskeletal pain were significantly related to sleep quality. The prevalence ratio of researcher group for short sleep duration was 1.27 (95% confidence interval: 1.02–1.58). The prevalence ratio of those aged 50 years and over was 0.47 (0.25–0.91) and of those in their 40s was 0.56 (0.35–0.91) for poor sleep quality compared to those in their 20s. The prevalence ratio of the obesity group for poor sleep quality was 1.53 (1.10–2.12). The prevalence ratio of musculoskeletal pain group for poor sleep quality was 1.92 (1.29–2.84).
Age, obesity and musculoskeletal pain were factors affecting the poor quality on sleep of daytime workers. In addition, work type related to short sleep duration.
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Job stress has been reported as a risk factor of psychological changes, which have been shown to be related to gastrointestinal diseases and symptoms such as functional dyspepsia. However, few studies have assessed the relationship between job stress and functional dyspepsia. Therefore, we investigated the relationship between job stress and functional dyspepsia in South Korea.
This study was conducted between May 23 and July 6, 2016 and included 901 workers in the display manufacturing sector. Subjects completed self-reported questionnaires, regarding Korean Occupational Stress Scale (KOSS), functional dyspepsia, Insomnia Severity Index-K, and health-related behaviors and job characteristics. Subjects were divided into functional dyspepsia-positive and -negative groups based on the Rome III criteria. The KOSS high-risk group was defined as subjects with KOSS score above the 75 percentile of KOSS reference value. Multiple logistic regression analysis was performed to investigate the association between job stress and functional dyspepsia.
In women, the risk of functional dyspepsia was significantly higher in the high-risk groups of the following KOSS subcategories in unadjusted model: job demand (OR 3.282, 95% CI 1.181–9.126), and occupational climate (OR 2.665, 95% CI 1.041–6.823). Even in adjusted model, the risk was significantly higher in the high-risk groups of the following KOSS subcategories: job demand (OR 3.123, 95% CI 1.036–9.416) and occupational climate (OR 3.304, 95% CI 1.198–9.115). In men, the risk of functional dyspepsia was not significant in all KOSS subcategories.
This study showed that job demand and occupational climates were associated with functional dyspepsia in female display manufacturing sector workers. Therefore, both clinical and mental health approaches should be used in the management of functional dyspepsia in women.
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Because of their positive impact on individuals’ performance and alertness, blue enriched white light sources are gaining popularity in households and industries. However, these sources of blue light spectrum may cause oxidative stress. On the other hand, there are no empirical studies investigating the negative effect of blue enriched white light on oxidative stress. Thus, the current study aimed at empirical assessment of the effect of such light sources on oxidative stress among night shift workers.
The study, which adopted a cross-sectional design, focused on 30 control room operators of a petrochemical complex. The subjects followed a shift-work schedule comprising 7 night shifts, 7 day shifts, and 7 days off. The subjects were exposed to 6500 K, 3000 K, and 17,000 K light sources (which have various degrees of blue light) during three consecutive work cycles, with each cycle lasting for 7 nights. In each light condition, three salivary measurements were conducted (at the beginning, in the middle, and at the end of the shift). The measurements were used to assess catalase (CAT), total thiol molecules (TTG), and total antioxidant capacity (TAC), and melatonin.
The results of repeated measures ANOVA showed that there was no significant difference among various light conditions with regard to salivary biomarkers (catalase, total thiol molecules, and total antioxidant capacity). There was however a significant difference between 3000 K and 17,000 K conditions with regard to the concentration of salivary melatonin (
Given that there was no significant difference among various light conditions in terms of biomarkers, it is concluded that using sources of light with high color temperature can be recommended. Nonetheless, because of the limitations of the present study (e.g. short period of intervention), it is suggested that care should be exercised in using such light sources.
Citations

Compared to 10 years ago, the ambient particulate matter 10 (PM10) and carbon monoxide (CO) levels in South Korea have decreased. However, compared to many other OECD countries, these levels are still too high. Concentration of air pollutants such as PM10 is especially higher during winter than during summer. The first step to rationally solving the air pollution problem in Korea is to identify the key air pollution sources during each season. This ecological study was performed to assess the association between the number of days the accepted PM10 and CO thresholds were exceeded and the concentration of potential emission sources in winter season 2015.
An emission inventory of the PM10 and CO emissions in the 232 administrative South Korean districts in January, 2015, and February, 2015 and December, 2015, and the population density, number of car registrations, number of car accidents, industrial power usage, and presence of a fossil-fuel power plant in each district was established on the basis of official web-page data from the government. For all emission source variables except power plants, the administrative districts were grouped into quartiles. Districts were also divided according to whether a power plant was present or not. Negative binomial regression was performed to assess the associations between the PM10 and CO air pollution (defined as ≥100 g/m3 and ≥ 9 ppm, respectively) and the concentration of each emission source.
Compared to the districts with the lowest population density, the districts with the third highest population density associated most strongly with air pollution. This was also observed for industrial power usage. Car accident number and car registration numbers showed a linear relationship with air pollution. Districts with power plants were significantly more likely to have air pollution than districts that lacked a plant.
Greater car numbers, industrial activity, and population density, and the presence of fossil-fuel plants associated with air pollution in the 2015 winter in South Korea. These data highlight the contaminant sources that could be targeted by interventions that aim to reduce air pollution, decrease the incidence of exposure, and limit the impact of pollution on human health.
The online version of this article (10.1186/s40557-018-0273-5) contains supplementary material, which is available to authorized users.
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In Korea, there were repeated radiation exposure accidents among non-destructive testing workers. Most of the cases involved local injury, such as radiation burns or hematopoietic cancer. Herein, we report a case of acute radiation syndrome caused by short periods of high exposure to ionizing radiation.
In January 2017, Korea Information System on Occupational Exposure (KISOE) found that a 31-year-old man who had worked in a non-destructive testing company had been overexposed to radiation. The patient complained of symptoms of anorexia, general weakness, prostration, and mild dizziness for several days. He was anemic. The venous injection areas had bruises and bleeding tendency. Blood and bone marrow testing showed pancytopenia and the patient was diagnosed with acute radiation syndrome (white blood cells: 1400/cubic mm, hemoglobin: 7.1 g/dL, platelets: 14000/cubic mm). He was immediately prohibited from working and blood transfusion was commenced. The patient’s radiation exposure dose was over 1.4 Gy (95% confidence limits: 1.1–1.6) in lymphocyte depletion kinetics. It was revealed that the patient had been performing non-destructive tests without radiation shielding when working in high places of the large pipe surface.
Exposure prevention is clearly possible in radiation-exposed workers. Strict legal amendments to safety procedures are essential to prevent repeated radiation exposure accidents.
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It is well known that ergonomic risk factors and back pain are related. However, few studies have examined the relationship between simultaneous exposure to these risk factors and back pain in a Korean population. We aimed to investigate the relationship between simultaneous exposure to ergonomic risk factors and work-related lower back pain (LBP) based on the fourth Korean Working Conditions Survey (KWCS).
The fourth KWCS (2014) was used for this study. Chi-square tests and logistic regression were used to assess relationship between 5 ergonomic risk factors and work-related LBP. We also analyzed the relationship between simultaneous exposure to 2 risk factors and work-related LBP.
All 5 ergonomic risk factors (fatigue-inducing and painful posture; lifting or moving people; dragging, pushing, or moving heavy objects; standing posture; and repetitive hand or arm movements) were significantly correlated with work-related LBP in the severe exposure group (adjusted odd ratios [aOR] 5.09, 95% confidence interval [CI] 4.46–5.83; aOR 1.98, 95% CI 1.62–2.42; aOR 2.09, 95% CI 1.82–2.40; aOR 1.79, 95% CI 1.60–2.01; aOR 2.04, 95% CI 1.82–2.30, respectively). When exposed to 2 risk factors simultaneously, the relationship between exposure and work-related LBP was not greater than exposure to only 1 risk factor in our study (usually exposed to ‘fatigue-inducing or painful posture’ aOR 2.17, 95% CI 2.02–2.34; high exposure to both ‘fatigue-inducing or painful posture’ and ‘dragging, pushing, or moving heavy objects’ aOR 2.00, 95% CI 1.82–2.20).
There was a strong relationship between severe exposure to each ergonomic risk factor and work-related LBP. However, when exposed to 2 ergonomic risk factors simultaneously, the relationship between exposure and work-related LBP was not stronger than when exposed to only 1 risk factor in our study.
Citations

Although one in two firefighters in South Korea have experienced work-related injuries, there are few studies which show the overview description on work-related injuries and its analysis regarding such causes. Therefore, we aimed to show the overview of compensated work-related injuries in order to serve fundamental data for establishing prevention policies on work-related injuries for Korean firefighters.
We requested the all claimed work-related injury data of Korean firefighters from 2010 to 2015 to the Korean National Fire Agency (NFA). The data from NFA including 2457 claimed cases was analyzed and we confirmed, 2154 approved work-related injuries for the kinds of job activities, cause of accident and type of injuries. Among 2154 approved cases, we analyzed more variables for the sex, age, and job duration of 1344 compensated cases through served text file on summary of accident.
The Government Employees Pension Service (GEPS) recognized 2154 (87.7%) approved work-related injuries among 2457 claimed cases. The incidence of work-related injuries per 1000 firefighters was 9.8 persons. By region, the incidence of work-related injuries per 1000 firefighters ranged from a maximum of 14.5 to a minimum of 4.0. The most common job activity caused the accident was fire suppression (18.0%), followed by Emergency medical services (EMS) (17.5%) and training (10.7%). The most common cause of these accident was movement imbalance (30.3%), followed by falls (18.9%) and traffic accident (13.4%). In these work-related injuries, sprains and bruises were the most common type of injury (27.2%), and the most commonly injured body site was the upper and lower back (25.3%). Data from identified 1344 firefighters showed that 1264 (94.0%) were male and 80 (6.0%) were female. Age group was the highest in the 40s with 623 cases (46.4%), and job duration was the highest with 650 cases in 5–10 years (48.4%).
In this study, we could obtain the preliminary data necessary to establish preventive measures, including the cause of accident and region with high accident rates. However, the number of applications for compensated injuries was very small compared to the frequency of injuries found in previous studies. The lack of appropriate treatment suggested that many firefighter injuries can become chronic. In this study, we suggest that it is necessary to introduce an injury monitoring system and improve the accessibility of compensated injuries.
Citations

Lighting is one of the environmental factors affecting the performance of the control room operators. Therefore, the aim of this study was to compare the control room operators’ visual performance in two different illumination conditions at a combined cycle power plant through field-work.
Sixteen operators in day shift were evaluated with the Freiburg Visual Acuity test (FrACT) software at two lighting systems with different intensities. It includes the first phase with fluorescent illumination system (Power: 40 W, Color Temperature: 4000 Kelvin, Luminous Flux: 2780 Lumen and Model: Pars Shahab) and the second phase with a combined illumination system includes fluorescent and LED (Power: 48 W, Color Temperature: 4000 Kelvin, Luminous Flux: 5400 Lumen and Model: Mazinoor).
Based on the results, visual performance index and visual acuity significantly increased after the intervention (
The results of this study showed that increasing the intensity of light from the values below the allowable limit to the values above the allowable limit would increase the visual indicators in individuals.
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The Korean Computerized Neurobehavioral Test (KCNT) is a psychological assessment tool used as part of Workers’ Special Health Examinations in Korea. Due to the spread of mobile technology, this study aimed to compare results of the KCNT administered on a tablet PC versus a desktop computer, and, therefore, assess the clinical applicability of mobile devices.
A total of 72 participants enrolled in this study. Their age, sex, and years of formal education were collected during an interview, as well as their typing speed. The test battery comprised five subtests: Simple Reaction Time test, Choice Reaction Time test, Digit Addition test, Symbol-Digit Substitution test, and Finger Tapping Speed test. Participants repeated the KCNT test battery in a randomly assigned order using four different testing systems: a desktop computer equipped with a conventional 106-key keyboard (System 1), a desktop computer equipped with a simplified keyboard (System 2), a tablet PC with a simplified 17-key on-screen keyboard (System 3), and a tablet PC equipped with a simplified keyboard (System 4).
Results of the Digit Addition test did not differ significantly for different testing systems. In contrast, results of the Simple Reaction Time test, Choice Reaction Time test, Symbol-Digit Substitution test, and Finger Tapping test were lower for the tablet PC (Systems 3 and 4) compared to the desktop computer (Systems 1 and 2). Systems 1 and 2 did not show significantly different results. Performance on System 3 was inferior to that on System 4, only for the Choice Reaction Time test and Finger Tapping Speed test. There were also significant differences in performance by computer familiarity when adjusted for age and education; however, the performance of each group on the test systems showed similar patterns.
It is not recommended to use a tablet PC to administer the KCNT to evaluate neurobehavioral performance for the Simple Reaction Time test and Choice Reaction Time test; however, tablet PCs with an on-screen keyboard may be used to perform the Digit Addition test, and the Symbol-Digit Substitution test and Finger Tapping Speed test to a limited degree.
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Since the 1980s, restructuring, which includes downsizing, closures, mergers, and privatization, has expanded worldwide, and various studies have investigated its effect on health. However, previous studies have mainly focused on restructuring accompanied by massive lay-offs, and the effect of a merger on workers’ health is still controversial. This study aims to investigate changes in worker depression and job stress after a merger without downsizing, which is unusual in Korea.
Repeated surveys were done in April 2014, April 2015, and April 2016 involving the participation of 209 subjects. Participants were divided into two groups, which were comprised of blue-collar workers (104) and white-collar workers (105). Sociodemographic characteristics, including age, education level, job tenure, gender, marital status, smoking status, and alcohol consumption, were measured via a survey. To determine the level of depression, the Korean version of the Center for Epidemiologic Studies Depression Scale (CES-D) was employed, and to investigate job stress, the Korean Occupational Stress Scale-Short Form (KOSS-SF) was used. For statistical analyses, Pearson’s chi-square test, the Student’s t-test, and repeated measure analysis of variance (ANOVA) were performed.
The results showed that depression (CES-D, F[2, 400] = 0.466,
This study showed that a merger without massive downsizing can cause negative health effects such as an changes in depression and increase in job stress. To improve the health of workers, both the immediate negative effects on health, and the long-term effects or their resolution over time should be considered prior to the merger.
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Intestinal parasitic infections are major public health problems worldwide, with high prevalence in low income countries where substandard food hygiene practices are common. Asymptomatic food handlers with poor personal hygiene could be potential sources of parasitic infections. This study was aimed to assess the prevalence of intestinal parasitic infections and associated factors among asymptomatic food handlers working at Haramaya University cafeterias, eastern Ethiopia.
A cross-sectional study was conducted among asymptomatic food handlers working at Haramaya University cafeterias from August 2015 to January 2016. Population proportion to size allocation and systematic random sampling techniques were used to identify the study participants. Stool samples were collected and examined simultaneouly using direct and modified formol ether concentration wet smear techniques. Data were entered and analyzed using SPSS version 20.0 software. Logistic regressions were applied to assess association between independent variable and intestinal parasitic infections. Statistical significance was declared at a
A total of 417 asymptomatic food handlers were enrolled in this study. Of these, females comprised 79.4%. Large proportion (39.3%) of food handlers were in the age group of 31–40 years. The overall prevalence of intestinal parasitic infections was 25.2% (95% CI: 18.3, 29.6).
The high prevalence of intestinal parasitic infections in this study highlights the importance of food handlers as probable sources of parasitic infections. Public health measures and sanitation programs should be strengthened to control the spread of intestinal parasitic infections.
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Resilient individuals have a comprehensive ability to adapt to various life circumstances. Psychological resilience predicts an individual’s physiological response to stress. The 10-item Connor-Davidson Resilience Scale (CD-RISC) is a widely used measure to quantify the level of self-perceived resilience. This study examined the psychometric properties of a Korean version of the 10-item Connor-Davidson Resilience Scale (10-item K-CD-RISC) on workers in Gumi, South Korea, exposed to hydrofluoric acid (HF).
The questionnaires included the 10-item K-CD-RISC and Beck Anxiety Inventor (BAI), the Impact of Event Scale-Revised-Korean version (IES-R-K), the Rosen-berg Self Esteem Scale (RSES), the Center for Epidemiologic Studies-Depression Scale (CES-D), and the Perceived Stress Scale (PSS). These were randomly distributed at 237 workplaces near the HF-spill site, in the Gumi 4 complex. The responses of 991 (67.3%) workers were analyzed.
The exploratory factor analysis shown that a single-factor model was consistent with the original design of the 10-item CD-RISC. The scale also demonstrated good internal consistency (Cronbach’s alpha = 0.95). Scores on the scale reflected different levels of resilience with respect to personal factors (age, gender, marital status, and education and income levels) that are thought to be differentiated. Differences of resilience were also reflected by psychiatric symptoms (anxiety and depression). Moreover, the total score of scale positively correlated with RSES, whereas the IES-R-K, BAI, CES-D, and the PSS negatively correlated with the 10-item K-CD-RISC.
The 10-item K-CD-RISC has good psychometric properties and is applicable for victims exposed to noxious chemical such as HF.
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Occupational stress and its related psychological strain is a concern among resident doctors that may affect patient care adversely. Residents face many stresses because of their high job demands in delivery of hospital care. They are often subject to work load and pressure due to direct involvement with patients, prolonged working hours, poor job opportunities and low support. Their multiple educational and clinical roles can also affect their performance and quality of personal or professional life. The aim of this study was to evaluate the occupational stress among residents of various medical specialties.
We aimed to explore the reasons of occupational stress in residents’ life and determine how we can enhance the stress-coping strategies and create more suitable conditions.
This cross-sectional analytical-descriptive study was conducted on all medical residents with various specialties in Shiraz University of Medical Sciences. Data was collected using Osipow occupational stress questionnaire and analyzed by SPSS software version 17.
The response rate was 88.8%. The average stress score of all residents was 156.35 out of 250. The highest and lowest average stress scores belonged to gynecology and dermatology specialties, respectively. The highest average score of the stress factors was related to the workload with the score of 35.09 of 50 (moderate to severe stress). The total stress score had a significant relationship with age (
Since most of the stressors were related to the workload, interventions such workload reduction, education about occupational stress and its management, promoting interpersonal relations and more supportive measures are recommended.
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This study aimed to identify the difference of perception about the role of appointing health officers by comparing and analyzing the response of entrustment workplace (EW) and specialized health management institution (SI). This is considered an important aspect of an institutional assessment to improve the quality of health management services.
A survey questionnaire was mailed to 122 SIs and 319 EWs nationwide. The questionnaire survey was about the general characteristics of SIs and EWs and main occupations for each evaluation item. In total, 81 SIs (66.4%) and 30 EWs responded to the questionnaire. A logistic regression analysis was performed to compare the opinions of SI and EW.
Based on the analysis, the items showing statistically significant differences were as follows. Doctors’ main tasks survey: “Guidance on their wearing personal protective equipment (PPE)” (OR: 4.58), “Guidance of improvement of work environment (WE)” (OR: 3.33), etc.; Nurses’ main tasks survey: “Guidance on their wearing PPE” (OR: 3.86), “Guidance for programs on health process in confined space (CS)” (OR: 0.36), “Guidance on the hearing conservation program (HCP)” (OR: 0.28), etc.; Industrial hygienist (IH)‘s main tasks survey: “Guidance of work through inspection (WTI)” (OR: 0.15), “Guidance on the improvement of WE” (OR: 0.32), “Management confirmation of substances used by process and Material Safety Data Sheet (MSDS)” (OR: 0.08), “Guidance on posting or keeping of MSDS and warning signs” (OR: 0.03), “Prevention of dust-induced medical problems” (OR: 0.28), “Guidance for programs of health process in CS” (OR: 0.39), etc.
It is necessary to educate the EWs to recognize the need for physicians to perform tasks, such as wearing a PPE, and instruction to improve WE. As for nurses’ tasks, such as education about the CS and the noise work, educating the nurses of the SI is regarded necessary as the demand of the EWs is considered. With respect to the unique tasks of IH, such as WE management and instructions for wearing PPE, among several other tasks of IH, training should be provided for improved IH recognition.
Citations

Occupational injuries increase burden on society as well as personal health. Low satisfaction with life may not only increases the risk of occupational injuries directly, but also influences other factors that increase the risk of occupational injury. Along with previous studies on the risk of occupational injury, we sought to explore the relationship between satisfaction with life and occupational injury.
The study participants were 6234workers health screened at a university hospital in Incheon. Information on occupational injury and satisfaction with life scale (SWLS) was obtained in a self-report format. Participants were allocated to one of four SWLS groups; the dissatisfied group, the slightly dissatisfied group, the slightly satisfied group, and the satisfied group. The analysis was performed using the chi-square test primarily and by logistic regression adjusted for potential confounders.
In men, the un-adjusted and adjusted odds ratios (ORs) of low satisfaction with life (SWLS< 20) were 1.98(CI1.55–2.53) and 1.81(CI 1.41–2.32), respectively. When the SWLS were divided into four groups, the adjusted ORs of the slightly satisfied (20–25), slightly dissatisfied(15–19), and dissatisfied(≤14) groups were 1.21, 1.72, and 2.70, respectively. That is ORs tended to increase linearly with decreasing SWLS score (p for trend < 0.001). In women, this relation was of borderline significance at best.
When subjects were dichotomized based on SWLS scores, for males, the cured and adjusted RRs of occupational injury in the low satisfaction with life group were1.91 (95% CI: 1.50–2.42) and 1.66 (95% CI: 1.30–2.13), and for females, the adjusted-RR was marginally significant (1.67; 95% CI: 0.93–2.99).
When subjects were divided into four groups by SWLS scores, adjusted RRs tended to increase linearly with decreasing SWLS score for males (slightly satisfied: 1.18, 95% CI: 0.77–1.82; slightly dissatisfied: 1.65, 95% CI: 1.08–2.52; dissatisfied: 2.22, 95% CI: 1.44–3.42; p for trend < 0.001) and for females (slightly satisfied: 1.17, 95% CI: 0.42–3.30; slightly dissatisfied: 1.56, 95% CI: 0.56–4.36; dissatisfied: 2.38, 95% CI: 0.84–6.74; p for trend = 0.040).
This study suggests that the risk of occupational injury was higher in workers not satisfied with life, and indicates attention to satisfaction with life may promote the health of workers.
Citations

Prevalence of thyroid cancer has been increasing rapidly worldwide, especially among women. There has been a debate as to whether such an increase represents consequences of over-diagnosis or a true increase. To find the occupational risk of Korean female workers in different industry sectors, we analyzed the data of Korean female workers.
National Female Worker Cohort data that contain information on total female workers were used for our analysis of prevalence of thyroid cancer (C73 according to KCD-5, 6 code) derived from National Health Insurance data. By combining industrial codes from National Health Insurance Service and those from Korea Workers’ Compensation and Welfare Service, the classification of industrial codes became to consist of the total of thirty three representing both non-office (NO) and office (O) categories. Both an internal comparison among female workers within the cohort and an external comparison to compare female workers with Korean general female population were carried out.
Among 149,258 female workers, 2,641 cases of thyroid cancers were identified. Differences in prevalence of thyroid cancer between female workers (40.5%) and general Korean female population (32.6%) were observed; however, the differences in prevalence of thyroid cancer between NO workers and O workers were not apparent. An analysis involving workers in Financial and insurance activities sector revealed that, standardized prevalence rate (SPR) of both NO (2.96, 95% CI = 2.01–4.20) and O workers (3.68, 95% CI = 3.10–4.33) increased significantly and that an AOR (adjusted odds ratio) increased marginally (1.38, 95% CI = 0.97–1.96). Further, when stratified in respect to the duration of employment, an AOR of female workers having been employed for more than 8 years showed a significant increase (1.63, 95% CI = 1.07–2.49).
Female workers had a higher risk of thyroid cancer than general female population but the difference between NO workers and O workers was not found to be significant in most industrial sectors. Further studies using data with information regarding specific occupational exposures are needed.
The online version of this article (10.1186/s40557-018-0259-3) contains supplementary material, which is available to authorized users.
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The present study aims to compare the pulmonary function of residents of Seoul special city (Seoul) and Jeju special self-governing province including Jeju city and Seogwipo city (Jeju), characterized by vastly different annual average airborne particulate matter with an aerodynamic diameter less ≤10 μm (PM10) concentrations, with the annual average PM10 concentration in Seoul being significantly higher than that in Jeju.
This cross-sectional study analyzed the pulmonary function test results and sociodemographic data of Korean adults ≥19 years of age derived from the 4th KNHANES, 2007–2009. A total of 830 individuals residing in Seoul or Jeju were included in this study. T-tests were used to analyze predicted values of forced expiratory volume in 1 sec (FEV1p), predicted values of forced vital capacity (FVCp) and FEV1/FVC ratio (FEV1/FVC), as dependent variables, to examine the differences in the subjects’ pulmonary function according to the city of residence. Stratified analysis was then performed to adjust for variables potentially affecting pulmonary function. The analysis was performed on subjects as a group and also following stratification according to sex and other variables.
Seoul residents had a significantly lower FVCp than that of the Jeju residents (difference: 3.48%,
The present analysis was based on cross-sectional data collected at one point in time. Therefore, unlike longitudinal studies, it does not establish a clear causal association between the variables. Nevertheless, this study found that pulmonary function among subjects residing in Seoul was significantly decreased compared to that of subjects residing in Jeju.
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South Korea is one of the countries with the longest working hours in the OECD countries. The aim of this study was to evaluate the effect of working hours on depressive symptoms and the role of job stress factors between the two variables among employees in South Korea.
This study used data from the Korea Working Conditions Survey in 2014. Study subjects included 23,197 employees aged 19 years or older who work more than 35 h per week. Working hours were categorized into 35–39, 40, 41–52, 53–68, and more than 68 h per week. Depressive symptoms were assessed using the WHO’s Well-Being Index with a cut-off score of 13. We calculated prevalence ratios of depressive symptoms according to working hours using log-binomial regression. Through the percentage change in prevalence ratios, we identified the extent of the role of job stress factors that explain depressive symptoms.
The risks of depressive symptoms were significantly higher in people who worked 35–39 h per week (PR: 1.09, CI: 1.01–1.18), 53–68 h/week (PR: 1.21, CI: 1.16–1.25), and more than 68 h/week (PR: 1.14, CI: 1.07–1.21) than 40 h/week, after adjusting for confounding variables. Job stress explained the effects of long working hours on depressive symptoms in about 20–40% of the groups working more than 40 h/week. Among the factors of job stress, social support was 10–30%, which showed the highest explanatory power in all working hours. Reward explained 15–30% in the more than 52 h working group, and reward was the most important factor in the working group that exceeded 68 h.
We showed the working hours could be an independent risk factor for depressive symptoms in employees. To improve workers’ mental health, it is important to strengthen social support in the workplace, to provide adequate rewards as they work, and ultimately to regulate the appropriate amount of working hours.
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This study aimed to enhance understanding of the epidemiologic characteristics of asbestos-related diseases, and to provide information that could inform policy-making aimed at prevention and compensation for occupational asbestos exposure, through analyzing asbestos-related occupational disease claims to Korea Workers’ Compensation and Welfare Service from 2011 to 2015.
We analyzed 113 workers who filed medical care claims or survivor benefits for asbestos exposure and occupational-related disease from 2011 to 2015. Among these claims, we selected approved workers’ compensation claims relating to malignant mesothelioma and lung cancer, and analyzed the general characteristics, exposure characteristics, pathological characteristics, and occupation and industry distribution.
Malignant mesothelioma and lung cancer occurred predominantly in males at 89.7 and 94%, respectively. The mean age at the time of diagnosis for malignant mesothelioma and lung cancer was 59.5 and 59.7 years, respectively, while the latency period for malignant mesothelioma and lung cancer was 34.1 and 33.1 years, respectively. The companies involving exposed workers were most commonly situated within the Busan-Ulsan-Gyeongnam region. Histology results for lung cancer indicated adenocarcinoma as the most common form, accounting for approximately one half of all claims, followed by squamous cell carcinoma, and small cell lung cancer. The most common occupation type was construction in respect of malignant mesothelioma, and shipbuilding in respect of lung cancer.
Considering the long latency period of asbestos and that the peak period of asbestos use in Korea was throughout the mid-1990s, damage due to asbestos-related diseases is expected to show a continued long-term increase. Few studies providing an epidemiologic analysis of asbestos-related diseases are available; therefore, this study may provide baseline data to assist in predicting and preparing for future harm due to asbestos exposure.
DUIH
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Anti-Mullerian hormone (AMH) in women is secreted by granulosa cells of antral follicles. AMH appears to be a very stable marker for ovarian function. It may be used to diagnosis cases of premature ovarian failure, polycystic ovary syndrome (PCOS), and ovarian tumors. It has been suggested that cadmium exposure can reduce female fecundity. The purpose of this study was to investigate whether environmental exposure to cadmium was associated with alterations in AMH with regards to age.
In a cross-sectional study, the data of premenopausal women living in Seoul, ranging from 30 to 45 of age was collected. The study included a total of 283 women who completed serum AMH and whole blood cadmium assessments. Linear regression analyses were used in order to examine the association between cadmium and AMH. Given that age was the strongest confounder in both cadmium and AMH concentrations, we stratified subjects by 5 years old and analyzed their data.
Geometric mean concentrations of blood cadmium and AMH were 0.97 μg/L and 3.02 ng/ml, respectively. Total association between cadmium and AMH was statistically significant (adjusted coefficient = − 0.34 (0.15),
The results of this study suggest that environmental exposure to cadmium may alter the AMH level of premenopausal women, depending on their age group.
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Korean teacher’s working conditions are deteriorating. There is concern about the deterioration of teachers’ health and voice disorder is one of the most common problems. Teacher’s vocal health is important for them and their students. The aim of the present study was to investigate working conditions that may affect voice disorders.
In all, 79 primary and secondary schools were randomly selected for a nationwide school system survey (
Teachers who reported voice symptoms more than once a week (fVD) made up 11.6%. In a multiple logistic regression, fVD was significantly associated with female, difficulty in applying for sick leave as needed, music teachers (primary school), and less than 6 h of sleep per day (primary school). The aOR for fVD was 2.72 (0.83–8.10) in the longest working hours group (> 52 h/wk) among the primary school teachers, and 1.90 (0.80–4.73) in the longest class hour group (≥ 20 h/wk), 1.52 (0.90–2.62) in homeroom teachers among the secondary school teachers, but not statistically significant.
Korean teachers’ working conditions are associated with fVDs. The school health system must take steps to prevent and treat voice disorders of teachers.
Citations

The aim of this study was to investigate the association between work-related factors and temporomandibular disorders (TMD) among female full-time employees using representative data from a national population-based survey.
Data from the Fourth Korea National Health and Nutrition Examination Survey IV (2007–2009) were used to analyze 1,612 women. Complex samples logistic regression was applied for adjusting for general characteristics and work-related factors to examine the association between work-related factors and TMD.
The prevalence of TMD was 12.8% in this study population. With respect to age, educational status, marital status, problem drinking, exercise, and stress, there were statistically significant differences in the prevalence of TMD. In logistic regression analyses on complex samples, based on 40 h or less per week, odds ratios (ORs) for respondents who worked 40–48 working hours, 49–60 working hours, and more than 60 h were 1.16 (95% confidence interval (CI) 0.69–1.94), 1.41 (95% CI 0.79–2.54), and 2.43 (95% CI 1.29–4.59), after adjusting for general characteristics, working schedule, employment status, and occupation.
This study found that long working hours were significantly associated with TMD in Korean female full-time employees.
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The concentration of particulate matter in the air varies depending on the region because it is lightweight and generated from a variety of sources. To assess the relationship between particulate matter and eye disease, this study analyzes the concentration data obtained from spatial analysis of particulate matter and emergency visit data.
The study included 769 residents of Daegu, Korea who had visited an emergency room for the problem of conjunctivitis or keratitis. Concentrations of PM10 and other air pollutants were obtained from the Korean Ministry of the Environment. PM10 concentrations and the number of patients from each of 143 administrative dongs (sub-municipal level administrative units) of the city of Daegu were obtained using spatial analysis. The patient distribution and PM10 concentration were mapped for comparison, and their relationship was examined using scatter plot, regression analysis, and the independent sample t-test.
The number of patients with conjunctivitis and keratitis was significantly higher in the regions of the top 20% areas than the bottom 20% areas in terms of PM10 concentration. The distribution of PM10 concentration and number of patients was visually similar on the map. The concentration of PM10 and the number of patients showed a dose–response relationship. When the concentrations of other air polluta9nts were controlled for, the numbers of conjunctivitis and keratitis patients were 0.04 per 1000 ER patients and 0.10 per 1000 ER patients, respectively.
As PM10 is associated with the prevalence of conjunctivitis and keratitis, measures to reduce particulate matter through environmental methods are needed.
The online version of this article (10.1186/s40557-018-0252-x) contains supplementary material, which is available to authorized users.
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Several studies suggest that serum ferritin concentrations reflect systemic inflammation, and high ferritin levels can increase the risk of hypertension in adult men. Shift work is also known to increase the risk of hypertension; however, there has been no study about the relationship between serum ferritin levels and the prevalence of hypertension according to the working type.
This cross-sectional study included 4,442 male participants (3,651 daytime workers and 791 shift workers) who participated in the fifth Korean National Health and Nutrition Examination Survey. Hypertension was defined as a systolic blood pressure greater than or equal to 140 mmHg, a diastolic blood pressure greater than or equal to 90 mmHg or the current use of antihypertensive medications regardless of blood pressure values. For the statistical analyses, serum ferritin levels were reclassified into quartiles, and complex sample analyses were used to evaluate the relationship between serum ferritin levels and the prevalence of hypertension according to the working type in this study.
Serum ferritin and shift work were positively associated with the prevalence of hypertension. The effect of interaction was above multiplicative. When compared to participants in the lowest serum ferritin quartile, the odds ratio for hypertension for participants in the highest serum ferritin quartile was 1.372 (1.027–1.833) in daytime workers and 2.009 (1.042–3.873) in shift workers after adjustment.
The prevalence of hypertension increased as ferritin levels increased in individuals, especially in shift workers.
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Prospective studies on occupational stress and depression among Korean workers are scarce. This study aimed to investigate the causal relationship between changes in occupational stress and the presence of depression.
This study analyzed data from a survey conducted with workers in a large Korean company (2015–2016). Occupational stress was measured using the Korean Occupational Stress Scale, and depression was screened using the WHO-5 Well-being Index. The levels of occupational stress were grouped in quartiles based on subjects’ occupational stress scores in 2015, and changes in occupational stress were measured using the score changes between the 2015 and 2016 surveys. Subjects were divided into four groups according to the presence or absence of depression in 2015 and 2016: a non-depressed group whose mental health did not change, a non-depressed group whose mental health deteriorated, a depressed group that continued to be depressed, and a depressed group whose symptoms of depression were alleviated. Logistic regression analysis was used to calculate the odds ratios (ORs) and confidence intervals (CIs) of the subjects’ deterioration in mood or alleviation of depression by occupational stress levels and changes.
The OR for developing depressive symptoms was 2.51 (95% CI 1.46–4.33) and 2.73 (95% CI 1.39–5.36) in the third and the fourth quartiles of occupational stress, respectively, compared to the first quartile. When the occupational stress score increased by 1 point, the OR for increasing depressive symptoms was 1.07 (95% CI 1.04–1.10). There was no significant difference in the alleviation of depressive symptoms between the groups by level of occupational stress. However, when the occupational stress score decreased by 1 point, the OR for alleviating depressive symptoms was 1.08 (95% CI 1.05–1.11).
The results showed that increased occupational stress increased the presence of depressive symptoms, and that reduced occupational stress suppressed the development of depressive symptoms. More attention should be paid to stress management among workers.
Citations

It is challenging to balance work and life, and little attention has been paid to the work–life balance and psychosocial well-being of South Koreans. We assessed the association between work–life balance and psychosocial well-being among paid Korean workers.
This study was based on data from the fourth Korean Working Conditions Survey. We evaluated only paid workers, which constituted 30,649 of the total of 50,007 subjects surveyed. Poor work–life balance was defined based on the goodness of fit between working hours and social commitments. Well-being was measured using the World Health Organization WHO-5 index. Poisson regression with robust variances was used to calculate the estimated prevalence ratios (PRs) with confidence intervals.
Poor work–life balance was associated with poor psychosocial well-being (PR = 1.25; 95% CI 1.21 to 1.28) even after adjusting for work-related and individual characteristics. Poor well-being was associated with low-level job autonomy (PR = 1.06; 95% CI 1.03 to 1.09), working for ≥53 h per week (PR = 1.10; 95% CI 1.06 to 1.14), blue-collar status (PR = 1.16; 95% CI 1.11 to 1.21), low-level support at work (PR = 1.32; 95% CI 1.29 to 1.36), age ≥ 50 years (PR = 1.21; 95% CI 1.15 to 1.26), the female gender (95% CI PR = 1.04; 95% CI 1.01 to 1.07), and cohabitation (living with somebody) (PR = 1.08; 95% CI 1.04 to 1.12). Good well-being was associated with high-intensity work (PR = 0.96; 95% CI 0.94 to 0.99), being the secondary earner in a household (PR = 0.82; 95% CI 0.79 to 0.85), and higher income (PR = 0.75; 95% CI 0.71 to 0.79).
Work–life balance was associated with psychosocial well-being after adjusting for both work-related and individual characteristics.
Citations

Using analysis of air samples from the workplace, we report on one case of pneumoconiosis in an individual who has been working in a polytetrafluoroethylene (PTFE) spraying process for 28 years.
The patient was diagnosed with granulomatous lung disease caused by PTFE using computed tomography (CT), lung biopsy and electron microscopy. To assess the qualitative and quantitative exposure to PTFE in workplace, Fourier transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDX) and thermogravimetric analysis (TGA) were performed on air samples from the workplace. The presence of PTFE particles was confirmed, and the airborne concentration of PTFE was estimated to be 0.75 mg/m3.
This case demonstrates that long-term exposure to PTFE spraying can cause granulomatous lung lesions such as pneumoconiosis; such lesions appear to be caused not by the degradation products of PTFE from high temperatures but by spraying the particles of PTFE. Along with air-sampling analysis, we suggest monitoring the concentration of airborne PTFE particles related to chronic lung disease.
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The aim of this study was to examine the relationship between the provision of safety and health information (PSHI) and occupational injuries.
This study was based on data from the 4th Korean Working Conditions Survey (KWCS) (2014). The sample consisted of data from 24,527 wage workers and was divided into high-risk and low-risk groups, depending on the probability of occupational injury. The high-risk group included subjects who could cause harm to themselves or others due to errors during work. We applied chi-squared tests and logistic regression analyses to examine the relationship between PSHI and occupational injuries.
In the high-risk group, workers with no PSHI showed an adjusted odds ratio of 1.81 for occupational injury (95% CI 1.33–2.47). In contrast, there was no statistically significant relationship between PSHI and the incidence of occupational injury in the low-risk group.
To prevent occupational injuries, multi-faceted approaches that take different levels of injury risk into account are needed. Among workers with a high risk of occupational injury, more a stringent safety education program is required.
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Health officers are an integral part of the occupational health service, and there have been studies to identify and improve the role of health officers in the workplace in order to improve the level of health care in the workplace. This study aimed to determine the contribution of health officers to the role of a health officer as prescribed by law and the percentage of health management work performed during work according to their qualifications.
Questionnaires were distributed to a total of 4584 workplaces where health officers were hired, and a total of 806 copies (17.58%) were returned. Of these, 336 questionnaires were finally analyzed, after excluding questionnaires missing the main variables. Using the data, the difference of role contributions and the percentage of health care work performed during the whole day according to the qualification of the health officer was analyzed.
Nurses were highly rated in the field of medical care, and industrial hygienists and air environmental engineers were highly rated in terms of chemicals and risk factor management. The percentage of health care work performed during the whole day differed according to the size of the workplace and industrial classification, but it was generally the lowest among air environmental engineers.
Health officers play a very different role in the workplace depending on their qualification, and they need support for areas of other qualification. In order to effectively manage the health of the staff at a workplace, it is necessary to consider the development of a support system for small- and medium-sized enterprises and adjust the conditions of employment of the health officer according to the law.

Despite the successful adaptation to high altitude, some differences do occur due to long term exposure to the hypoxic environment. The effect of long term high altitude exposure on cardiac autonomic adjustment during basal and post-exercise recovery is less known. Thus we aimed to study the differences in basal cardiac autonomic adjustment and its response to exercise in highlanders and to compare it with lowlanders.
The study was conducted on 29 healthy highlander males who were born and brought up at altitude of 3000 m and above from the sea level, their cardiac autonomic adjustment was compared with age, sex, physical activity and ethnicity-matched 29 healthy lowlanders using Heart Rate Variability (HRV) during rest and recovery from sub-maximal exercise (3 m step test). Intergroup comparison between the highlanders and lowlanders and intragroup comparison between the rest and the postexercise recovery conditions were done.
Resting heart rate and HRV during rest was comparable between the groups. However, heart rate recovery after 3 min step test was faster in highlanders (
Highlanders completely recovered back to their resting state within five minutes from cessation of step test with parasympathetic reactivation; however, recovery in lowlanders was delayed.
The online version of this article (10.1186/s40557-018-0240-1) contains supplementary material, which is available to authorized users.
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We reviewed articles to clarify the current evidence status for 1) types of cancer which related to benzene exposure, and 2) certain benzene exposure level which might cause the hematopoietic cancers. Hematopoietic function of the bone marrow is involved in the production of all blood cells types. The benzene metabolites including benzoquinone and mucoaldehyde affect hematopoietic stem cells as well as differentiation steps of progenitor cells for each blood cell. Hence, we concluded that benzene was associated with all lymphohematic carcinogenesis. First, it is supported by biological plausibility. Second, it is supported by meta-analysis although sing study did not show relationship due to lack of sample size or statistical power. More recent studies show lesser exposed level related to risk of cancer, compare to past studies did. Actually, early studies show the risk of malignancies in workers who exposed more than 200 ppm-years. However, only 0.5 to 1 ppm-year benzene exposed show significant linking to risk of malignancies in recent study. As reviewed research articles, we concluded that the relatively lower exposure level, such as 0.5–1 ppm-year, will be considering at risk of hematopoietic cancer. However, more research needs to be done on dose-response analysis.
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Bus drivers are known to be highly at risk of cardiovascular diseases. In this study, we assessed the cardiovascular disease prevalence of bus company employees in Seoul, South Korea, and compared the results to those of general workers.
We analyzed the 2014 Korean National Health Insurance (NHI) data and defined hypertension, diabetes, dyslipidemia, ischemic heart disease, and cerebrovascular disease based on the KCD-6 medical diagnoses. We used bus company employees as surrogate participants of bus drivers due to the characteristics of Korean NHI data. We identified bus company employees in Seoul based on one’s workplace which the insurance is registered. The prevalence of five diseases was compared between the bus company employees and general workers. We also calculated the odds ratios (OR) of five diseases between the bus company employees and general workers. To compensate the vast demographical differences between the two groups, we performed propensity score matching.
Bus company employees have higher OR for having hypertension (OR 1.33, 95% CI: 1.28–1.39), diabetes mellitus (1.14, 95% CI: 1.08–1.22), and dyslipidemia (1.23, 95% CI: 1.17–1.29) than the general workers or propensity score matched controls. However, the OR of having ischemic heart disease were not significant. The OR of cerebrovascular disease were lower in bus company employees than in the general workers after adjusting the covariates, but similar in the propensity score matched model.
This study showed that the ORs of cardiovascular disease risk factors are high in bus company employees when compared to the general working population. Further studies with the longitudinal design should be conducted to confirm the causal association.
Citations

Numerous studies have shown that healthcare professionals are exposed to psychological distress. However, since most of these studies assessed psychological distress using self-reporting questionnaires, the magnitude of the problem is largely unknown. We evaluated the risks of mood disorders, anxiety disorders, sleep disorders, and any psychiatric disorders in workers in healthcare industry using Korea National Health Insurance (NHI) claims data from 2014, which are based on actual diagnoses instead of self-evaluation.
We used Korea 2014 NHI claims data and classified employees as workers in the healthcare industry, based on companies in the NHI database that were registered with hospitals, clinics, public healthcare, and other medical services. To estimate the standardized prevalence of the selected mental health disorders, we calculated the prevalence of diseases in each age group and sex using the age distribution of the Korea population. To compare the risk of selected mental disorders among workers in the healthcare industry with those in other industries, we considered age, sex, and income quartile characteristics and conducted propensity scored matching.
In the matching study, workers in healthcare industry had higher odds ratios for mood disorders (1.13, 95% CI: 1.11–1.15), anxiety disorders (1.15, 95% CI: 1.13–1.17), sleep disorders (2.21, 95% CI: 2.18–2.24), and any psychiatric disorders (1.44, 95% CI: 1.43–1.46) than the reference group did. Among workers in healthcare industry, females had higher prevalence of psychiatric disorders than males, but the odds ratios for psychiatric disorders, compared to the reference group, were higher in male workers in healthcare industry than in females.
The prevalence of mood disorders, anxiety disorders, sleep disorders, and all psychiatric disorders for workers in the healthcare industry was higher than that of other Korean workers. The strikingly high prevalence of sleep disorders could be related to the frequent night-shifts in these professions. The high prevalence of mental health problems among workers in healthcare industry is alarming and requires prompt action to protect the health of the “protectors.”
Citations
Obstetrics Healthcare Providers’ Mental Health and Quality of Life During COVID-19 Pandemic: Multicenter Study from Eight Cities in Iran


Occupational accidents are of most important consequences of globalization in developing countries. Therefore, investigating the causes of occupational accidents for improving the job situation and making operational policy is necessary. So the aim of this study was to investigate factors affecting the fatal occupational accidents and also calculate the years of life lost for dead workers.
This cross-sectional study was conducted on data related to the 6052 injured workers that was registered in the 2013 registry system of the Ministry of Health and Medical Education of Iran. Variables including sex, education, age, job tenure, injury cause, referred location of injured workers, occupation, shift work, season, accident day, damaged part of the body were chosen as independent variables. The Chi-squared and Fisher exact tests were used for univariate analysis and then exact multiple logistic regression was carried out to identify independent risk factors of fatal occupational accidents. Finally, for dead workers, years of life lost, according to the injury causes was calculated.
Among the 6052 accidents reported, 33 deaths were recorded. Chi-square and Fisher exact tests showed that factors including: current job tenure (
In Iran, fatal accident odds in workers with job tenure more than 1 year was less in comparing to the workers with job tenure less and equal to 1 year. Also odd of death for electrical shock was more than other causes of injuries. So it seems that employing of workers who have more than one-year work experience in a specific job and using of appropriate safeguards will be useful for the reducing of fatal occupational accidents.
Citations

Previous studies have classified cameramen’s job as physiologically heavy work and identified the risk factors of work-related musculoskeletal disorders (WRMDs) in cameramen. However, those studies limited their research subjects to cameramen. In this study, we compared the frequency and severity of WRMDs between cameramen and office workers.
A total of 293 subjects working in four broadcasting companies in Korea were recruited. A questionnaire survey was conducted for a month, starting in October 2016. The subjects were divided into cameramen and office workers according to their occupation. We compared the frequency and severity of WRMDs and ergonomic risk assessment results between the two groups.
The high-risk WRMD group had a higher proportion of cameramen than office workers. Moreover, the high ergonomic risk group also had a higher proportion of cameramen than office workers for WRMDs in the upper extremities and waist+lower extremities. In the multivariable-adjusted model comparing cameramen and office workers, the odds ratio (OR) with 95% confidence interval (95% CI) for high-risk WRMDs was 3.50 (95% CI: 1.92–7.72) for the upper extremities and 3.18 (95% CI: 1.62–6.21) for the waist and the lower extremities. The ORs by body parts were 3.11 (95% CI: 1.28–7.57) for the neck, 3.90 (95% CI: 1.79–8.47) for the shoulders, and 4.23 (95% CI: 1.04–17.18) for the legs and feet.
Our study suggests that cameramen are at high risk of WRMDs. Workplace improvements and management of the neck, shoulders, and lower extremities, which are susceptible to WRMDs, are necessary to prevent musculoskeletal disorders among cameramen.
Citations

Organic solvent-induced chronic toxic encephalopathy (CTE) is known as a non-progressive disorder that does not progress after diagnosis. The authors present a case those symptoms worsened after continued exposure to organic solvent after returning to work. Because such a case has not been reported in South Korea to the best of our knowledge, we intend to report this case along with literature review.
A 59-year-old man, who performed painting job at a large shipyard for 20 years, was receiving hospital treatment mainly for depression. During the inpatient treatment, severe cognitive impairment was identified, and he visited the occupational and environmental medicine outpatient clinic for assessing work relatedness. In 1984, at the age of 27, he began performing touch-up and spray painting as a shipyard painter. Before that he had not been exposure to any neurotoxic substances. In 2001, at the age of 44, after 15 years of exposure to mixed solvents including toluene, xylene and others, he was diagnosed with CTE International Solvent Workshop (ISW) type 2A. After 7 years of sick leave, he returned to work in 2006. And he repeated return-to-work and sick leave in the same job due to worsening of depressive symptoms. He had worked four times (2006–2010, 2011–2011, 2011–2011, 2016–2017) for a total of 5 years as a shipyard painter after first compensation. During the return-to-work period, the mean values of the mixed solvent index ranged from 0.57 to 2.15, and except for a one semiannual period, all mean values were above the standard value of 1. We excluded other diseases that can cause cognitive impairment like central nervous system diseases, brain injury, psychological diseases and metabolic diseases with physical examinations, laboratory tests, and brain image analysis. And finally, throughout neuropsychological tests, an overall deterioration in cognitive function was identified compared to 2002, and the deterioration types was similar to that often shown in the case of CTE; thus a diagnosis of CTE (ISW) type 3 was made.
This case is showing that CTE can go on with continued exposure to mixed solvents. Appropriate “fitness to work” should be taken to prevent disease deterioration especially for the sick leave workers.
Citations

Many studies show that organizational justice (OJ) is related to psychological determinants of employee health. To prevent health problems related to OJ in Korean workplaces and to accurately measure OJ, we developed the Korean version of the Organizational Justice Questionnaire (K-OJQ) and assessed its validity and reliability.
A questionnaire draft of the K-OJQ was developed using back-translation methods, which was preliminary tested by 32 employees in Korea. Feedback was received and the K-OJQ was finalized. This study used data from 303 workers (172 males, 131 females) in Korea using the K-OJQ, job stress, and lifestyle questionnaires.
Cronbach’s α coefficients of the internal consistency reliability was 0.92 for procedural justice and 0.94 for interactional justice. Factor analyses using SPSS 24 and Amos 23 extracted two expected factors, named procedural justice (7 items; range, 1.0–5.0) and interactional justice (6 items; range, 1.0–5.0) and showed a reliable fit (χ2 = 182;
The K-OJQ was objectively validated through statistical methods.
The online version of this article (10.1186/s40557-018-0238-8) contains supplementary material, which is available to authorized users.
Citations


This study aimed to analyze environmental tobacco smoking exposure in female nonsmokers by public transportation mode using representative data of Koreans.
Data from the Second Korean National Environmental Health Survey (2012–2014) were analyzed. Urine cotinine was analyzed by public transport behavior, secondhand smoke exposure, socioeconomic factors, and health-related factors. Participants were 1322 adult females; those with the top 75% urine cotinine concentrations were assigned to the high exposure group. A logistic regression analysis was performed considering appropriate weights and stratification according to the sample design of the Second Korean National Environmental Health Survey.
The geometric mean of urine cotinine concentrations differed according to public transportation modes: subway (1.66 μg/g creatinine) bus (1.77 μg/g creatinine), and taxi (1.94 μg/g creatinine). The odds ratio [OR] was calculated for the high exposure group. The OR of the taxi (2.39; 95% confidence interval, 1.00–5.69) was statistically significantly higher than the subway value (reference), and marginally significant after adjusted with life style, sociodemographic factors and involuntary smoking frequency (2.42, 95% confidence interval, 0.97–6.04).
The odds ratio of passengers who mainly used taxis was marginally significantly higher than those of passengers who used subways and buses after adjusted with life style and sociodemographic factors. Implementation of supplementary measures and further studies on exposure to environmental tobacco smoking in taxis are warranted.
Citations

Polycyclic aromatic hydrocarbons (PAHs) produced by incomplete combustion have negative effects on human health due to their carcinogenicity and teratogenicity. Indoor sources of PAHs include tobacco smoke, heating sources, and cooking. This study evaluated the relationship between human PAH exposure and residence characteristics.
This study was based on the second Korean National Environmental Health Survey (2012–2014). Non-smoking housewives were included in the analyses (
The adjusted geometric mean concentrations of urinary 2-hydroxyfluorene and 1-hydroxyphenanthrene were significantly higher in the group residing within 100 m of a major road (
Our study shows the evidence of associations between some urinary PAH metabolite levels (1-hydroxyphenanthrene and 1-hydroxypyrene) and residence characteristics. Additional studies are needed to clarify these associations.
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Lead and cadmium have been identified as risk factors for hearing loss in animal studies, but large-scale studies targeting the general human population are rare. This study was conducted to investigate the link between heavy metal concentrations in blood and hearing impairment, using a national population-based survey.
The study participants comprised 6409 Koreans aged 20 or older, who were included in the Fifth and Sixth Korea National Health and Nutrition Examination Surveys (KNHANES 2010–2013). Hearing impairment was categorized into two types, low- and high-frequency hearing impairment, using pure tone audiometry. Low-frequency hearing impairment was defined as having a binaural average of hearing thresholds for 0.5, 1, and 2 kHz exceeding 25 dB, and high-frequency hearing impairment was defined as having a binaural average of hearing thresholds for 3, 4, and 6 kHz exceeding 25 dB. The blood levels of heavy metals (lead and cadmium) were classified into quartiles. Cross-sectional association between hearing impairment and the level of heavy metals (lead and cadmium) was examined in both sexes. Multivariate logistic regression was used to obtain adjusted odds ratios (ORs) and 95% confidence intervals (CIs).
Among men, the prevalence of low- and high- frequency hearing impairment was 13.9% and 46.7%, respectively, which was higher than the prevalence among women (11.8% and 27.0%, respectively). Regarding lead, the adjusted OR of high-frequency hearing impairment for the highest blood level group versus the lowest group was significant in both men (OR = 1.629, 95% CI = 1.161–2.287) and women (OR = 1.502, 95% CI = 1.027–2.196), after adjusting for age, body mass index, education, smoking, alcohol consumption, exercise, diagnosis of diabetes mellitus, hypertension, and noise exposure (occupational, loud, firearm noises). No links were found between blood lead levels and low-frequency hearing impairment, or between blood cadmium levels and low- or high-frequency hearing impairment in either sex.
The present study findings suggest that even exposure to low-level lead is a risk factor for high-frequency hearing loss. A prospective epidemiologic study should be conducted to identify the causal relationship between human health and exposure to heavy metals, and efforts to reduce heavy metal exposure in the general population should continue.
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The Korea Radiation Effect & Epidemiology Cohort - The resident cohort (KREEC-R) study concluded that there is no epidemiological or causal evidence supporting any increase in cancer risks resulting from radiation from Korean nuclear power plants (NPPs). But the risks of thyroid cancer in women were significantly higher in residents living near NPPs than control. Debate about the cause of the pattern of thyroid cancer incidence in women is ongoing and some researchers argue that detection bias influenced the result of KREEC-R study. Therefore there was a need to investigate whether residents living near NPPs who were assessed in the KREEC-R were actually tested more often for thyroid cancer. We evaluated the possibility of detection bias in the finding of the KREEC-R study based on materials available at this time.
Using the KREEC-R raw data, we calculated age standardized rates (ASRs) of female thyroid cancer and re-analyzed the results of survey on the use of medical services. We also marked the administrative districts of residents who received the Radiation Health Research Institute (RHRI) health examinations and those in which thyroid cancer case occurred as per the Chonnam National University Research Institute of Medical Sciences (RIMS) final report on maps where the locations of NPPs and 5 km-radii around them were also indicated. And we compared the incidence rates of Radiation-induced cancer measured between the first period when RHRI health examinations were not yet implemented, and the second period when the RHRI health examinations were implemented.
The ASR for the far-distance group, which comprised residents living in areas outside the 30 km radius of the NPPs, increased rapidly after 2000; however, that of the exposed group, which comprised residents living within a 5 km radius of the NPPs, started to increase rapidly even before 1995. The frequencies of the use of medical services were significantly higher in the intermediate proximate group, which comprised residents living within a 5–30 km radius of the NPPs, than in the exposed group in women. In case of female thyroid cancer, the second period ASR was higher than the first period ASR, but in case of female liver cancer and female stomach cancer no significant difference were observed between the periods. On map, many administrative districts of residents who received RHRI health examinations and most administrative districts in which thyroid cancer case occurred on RIMS final report were outside 5 km-radii around NPPs.
We could not find any evidence supporting the assertion that detection bias influenced the increased risks of female thyroid cancer observed in the exposed group of the KREEC-R study, as opposed to the control group.
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Exposure to sustained high concentrations of HCFC-123 is known to be hepatotoxic. We report two simultaneous cases of toxic hepatitis related to exposure to 2,2-dichloro-1,1,1-trifluoroethane (HCFC-123), a common refrigerant, at a Korean fire extinguisher manufacturing facility.
Patients A and B were men aged 21 and 22 years, respectively, with no notable medical histories. They had recently started working for a manufacturer of fire extinguishers. During the third week of their employment, they visited the emergency center of a general hospital due to fever, lack of appetite, and general weakness. At the time of their visit, they were suspected as having hepatitis due to elevated aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), gamma-glutamyl transferase (GGT), and total bilirubin levels and were hospitalized. However, as their condition did not improve, they were moved to a tertiary general hospital. After conservative treatment, one patient improved but the other died from acute hepatic failure. Assessments of the work environment showed that the short-term exposure levels of HCFC-123 for valve assembly processes were as high as 193.4 ppm. A transjugular liver biopsy was performed in patient A; the results indicated drug/toxin-induced liver injury (DILI). Given the lack of a medical history and the occupational exposure to high levels of HCFC-123, a hepatotoxic agent, the toxic hepatitis of the workers was likely related to HCFC-123 exposure.
Work environment assessments have not included this agent. To the best of our knowledge, we are the first to report a case of death related to HCFC-123-induced liver damage. Our findings suggest that exposure standards and limits for HCFC-123 must be developed in Korea; work environments will have to be improved based on such standards.
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