Background Mental illness is known to be caused by genetic, biological, and environmental risk factors. Although previous studies have established the link between mental illness and job stress, most of them are limited to major depression disorder. Therefore, this study examined the relationship between job stress and bipolar spectrum disorder (BSD). Methods This is a cross-sectional study based on a survey conducted in April 2017 at an electronic parts manufacturing company in Busan. In a total of 441 workers, the degree of BSD was identified using the Korean version of the Mood Disorder Questionnaire, and the degree of job stress was identified using the Korean Occupational Stress Scale Short Form. This study also identified general characteristics of workers and job-related factors. The χ 2 test and Fisher's exact test was conducted to determine the differences among the variables, based on BSD. Multiple logistic regression analysis was conducted to determine the influence of independent variables on BSD. Results Cross-analysis showed significant differences between the BSD high-risk and low-risk groups regarding age, sex, occupation, smoking, problem drinking, job stress total score, occupational climate, and major depression disorder symptom. In addition, the significant differences between the BSD high-risk and low-risk groups about job stress were observed in terms of job demand, job insecurity, and occupational climate. A multiple logistic regression analysis revealed that the high-risk group in the job stress group had a higher effect on BSD than the low-risk group (odds ratio [OR]: 2.32, 95% confidence interval [CI]: 1.10–4.88). Among the categories of job stress, high-risk groups in 3 areas—job demand (OR: 2.56, 95% CI: 1.27–5.17), job insecurity (OR: 4.42, 95% CI: 1.19–16.42), and occupational climate (OR: 2.55, 95% CI: 1.29–5.05)—were more likely to have an impact on BSD than the low-risk groups. Conclusions This study demonstrated that the high-risk groups of job stress total score, job demand, job insecurity, and occupational climate had a more significant effect on BSD than the low-risk groups. As workers with BSD may have difficulties in their work and personal lives, there is a need to manage job stress to prevention of BSD.

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Background Studies on the relationship between organic solvent exposure and chronic kidney disease (CKD) have presented inconsistent results. Definition of CKD has changed in 2012, and other cohort studies have been newly published. Therefore, this study aimed to newly confirm the relationship between organic solvent exposure and CKD through an updated meta-analysis including additional studies. Methods This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. The search was conducted on January 2, 2023 using Embase and MEDLINE databases. Case-control and cohort studies on the relationship between organic solvent exposure and CKD were included. Two authors independently reviewed full-text. Results Of 5,109 studies identified, a total of 19 studies (control studies: 14 and cohort studies: 5) were finally included in our meta-analysis. The pooled risk of CKD in the organic solvent exposed group was 2.44 (1.72–3.47). The risk of a low-level exposure group was 1.07 (0.77–1.49). The total risk of a high-level exposure group was 2.44 (1.19–5.00). The risk of glomerulonephritis was 2.69 (1.18–6.11). The risk was 1.46 (1.29–1.64) for worsening of renal function. The pooled risk was 2.41 (1.57–3.70) in case-control studies and 2.51 (1.34–4.70) in cohort studies. The risk of subgroup classified as ‘good’ by the Newcastle Ottawa scale score was 1.93 (1.43–2.61). Conclusions This study confirmed that the risk of CKD was significantly increased in workers exposed to mixed organic solvents. Further research is needed to determine the exact mechanisms and thresholds. Surveillance for kidney damage in the group exposed to high levels of organic solvents should be conducted. Trial Registration PROSPERO Identifier: CRD42022306521

It is important to assess the blood flow of fingers in the verification of hand-arm vibration syndrome. In the Republic of Korea, most assessments of the blood flow in the fingers are performed using a cold provocation test with finger skin color change. However, this test is a non-objective method with a relatively low sensitivity, leading to possible social and legal problems. Thus, we reviewed the characteristics of several tests that assess the blood flow in the fingers. Among these tests, using the radioactive isotope method, Raynaud’s scan has a relatively higher sensitivity and specificity than other tests, provides objective results, and is approachable in many hospitals. So we suggest using Raynaud's scan as an alternative test when cold provocation test with finger skin color change is negative in vibration exposed worker.

An epidemiological case investigation of occupational cancer is conducted to determine the causation between the cancer and the worker's job. This review describes the overall process of work-relatedness assessment of the epidemiological case investigation through a case of upper urinary tract cancer (UUTC) in benzidine exposed worker in dyeing industry. Medical referrals, occupational history, material safety data sheet, and working environment monitoring submitted by the Korea Workers' Compensation and Welfare Service were reviewed. We further investigated literatures about the cotton dyeing industry, the domestic law and working environment monitoring reports. Benzidine was listed as an International Agency for Research on Cancer risk factor only for bladder cancer among urinary tract cancers, requiring different logical grounds for establishing causation. A literature review was conducted on the metabolic pathways of benzidine to establish biological plausibility. In addition, several papers were investigated that UUTC and bladder cancer share risk factors to extrapolate the epidemiological studies of bladder cancer. Epidemiologic studies of benzidine and bladder cancer were investigated. The worker is a 71-year-old man and performed dyeing and transporting at several dyeing factories for 29 years. The worker was diagnosed with UUTC based on radiologic and histologic results. It was critical to consider that he worked as a dyer for 3 years. The cancer was diagnosed in 2018, with a latent period of approximately 35 years. The worker performed cotton dyeing, and benzidine-based dye was mainly used. The quantitative exposure level of benzidine was reported from non-detection to 397.4 µg/m 3 . In biological metabolisms, N-acetylhydroxylamine changes DNA structure of urothelium. As a result of reviewing 4 epidemiological studies, the standardized incidence ratio and standardized mortality ratio were significantly high with 3 years of exposure. Work-relatedness was finally assessed as probable based on biological mechanisms and epidemiological evidence. This review will help solutions for work-relatedness assessment processes.