Journal of Occupational Health最新文献

Objectives: There has been limited research on demographic and work-related characteristics of general and workplace loneliness. The present descriptive cross-sectional study aimed to determine the demographic and work-related correlates of general and workplace loneliness in a general working population of Japan.

Methods: We recruited 25 000 persons aged 20 years or older and employed by a company, organization, or government agency. We limited the sample to only employees for this analysis. Demographic and work-related characteristics were assessed by a self-report questionnaire. General and workplace loneliness were measured by single-item questions and dichotomized.

Results: A total of 24 021 respondents were subjected for the analysis. Prevalences of general and workplace loneliness were 9.0% and 8.3%, respectively. Those who responded "others" or refused to answer a gender question (possibly gender minority), were middle-aged, not married, with a low household income, working in the manufacturing sector (compared with some service sectors), and reporting long working hours were associated with both general and workplace loneliness. Middle-aged groups and work hours were significantly associated with workplace loneliness after adjusting for general loneliness.

Conclusions: Common demographic and work-related correlates were found for both general and workplace loneliness. Middle age and working long hours may be factors for workplace loneliness, independent of general loneliness, in Japan.

Objectives: This study aimed to establish a method to determine workers' exposure concentrations to airborne nitrilotriacetic acid (NTA).

Methods: The sampler used an air sampling cassette containing a glass-fiber filter (GFF). After sampling, NTA extracted from the GFF using ultrapure water was derivatized using a boron trifluoride-methanol complex methanol solution and analyzed using a gas chromatograph-mass spectrometer. The developed method was validated for the following parameters: retention efficiency, storage stability, method quantitation limit, and reproducibility.

Results: The retention efficiency for NTA on the GFF was 94%-101%, with the relative SD indicating the overall reproducibility (range 0.9%-2.4%). NTA on the GFF was stable at 4°C for at least 7 days. The method quantitation limit was 4.8 μg per sample.

Conclusions: The developed method will be useful for risk assessments because it can determine workers' exposure concentrations to NTA ranging from 0.02 to 4 mg/m3 in a 240 L sampling volume; the quantitation limit is 4.8 μg per sample.

It was previously thought that the particles inhaled by humans and having adverse effects were micron-sized; particles with a particularly high content of crystalline silica were thought to have harmful effects. In recent years, manufactured materials have been further refined to nano-level particles, and it has been reported that these ultrafine particles have different adverse effects, making it necessary to perform occupational health management for chemicals that differ from micron-sized particles. Here we report the adverse effects of carbon nanotubes, welding fumes, and organic substances as examples of nanoparticles.

Before 2000, very little attention had been paid to the health effects of indium, a rare metal, because there was very little information in the literature on its toxicity. A fatal case of indium-tin oxide (ITO) inhalation occurred in 2001, followed by concerns regarding occupational exposure to indium compounds and their health effects. Epidemiological studies and case reports have established a causal relationship between the inhalation of insoluble indium compounds, mainly ITO, and the development of lung damage. This review focuses on the results of animal studies of ITO and other insoluble indium compounds. Available data indicate that insoluble indium compounds such as ITO, indium arsenide (InAs), indium phosphide (InP), and copper indium gallium diselenide (CIGS) solar cell materials are toxic to the lungs of animals. In addition to lung damage, ITO nanoparticles have been found to cause kidney damage, whereas InAs, InP, and ITO cause testicular damage. Furthermore, there is compelling evidence for the carcinogenic potential of InP in long-term inhalation studies using rats and mice, which was evident in rats exposed to ITO. Based on the results of these animal experiments, the International Agency for Research on Cancer evaluated InP as probably carcinogenic to humans (Group 2A) and ITO as possibly carcinogenic to humans (Group 2 B). Based on the results of animal studies, it should be noted that occupational exposure of humans to insoluble indium compounds not only may cause lung damage, but also lung carcinogenesis and kidney or testicular damage in the future. Greater attention should be directed towards human occupational exposure to insoluble indium compounds.

Objectives: Falls are among the most prevalent workplace accidents, necessitating thorough screening for susceptibility to falls and customization of individualized fall prevention programs. The aim of this study was to develop and validate a high fall risk prediction model using machine learning (ML) and video-based first 3 steps in middle-aged workers.

Methods: Participants to provide training data (n = 190, mean [SD] age = 54.5 [7.7] years, 48.9% male) and validation data (n = 28, age = 52.3 [6.0] years, 53.6% male) were enrolled in this study. Pose estimation was performed using a marker-free deep pose estimation method called MediaPipe Pose. The first 3 steps, including the movements of the arms, legs, trunk, and pelvis, were recorded using an RGB camera, and the gait features were identified. Using these gait features and fall histories, a stratified k-fold cross-validation method was used to ensure balanced training and test data, and the area under the curve (AUC) and 95% CI were calculated.

Results: Of 77 gait features in the first 3 steps, we found 3 gait features in men with an AUC of 0.909 (95% CI, 0.879-0.939) for fall risk, indicating an "excellent" (0.9-1.0) classification, whereas we determined 5 gait features in women with an AUC of 0.670 (95% CI, 0.621-0.719), indicating a "sufficient" (0.6-0.7) classification.

Conclusions: These findings suggest that fall risk prediction can be developed based on ML and the first 3 steps in men; however, the accuracy was only "sufficient" in women. Further development of the formula for women is required to improve its accuracy in the middle-aged working population.

Objectives: This study aimed to develop a method for determining workers' exposure concentrations to airborne N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD).

Methods: A hydrophobic polytetrafluoroethylene (HPB PTFE) membrane filter was used as the sampling medium. IPPD was extracted from the HPB PTFE filter with acetonitrile, and its concentration in the extracted solution was determined using a high-performance liquid chromatograph equipped with a photodiode array detector. The validating method was performed using the following parameters: extraction and retention efficiency, storage stability, method quantitation limit, and reproducibility.

Results: The IPPD extraction efficiency from the spiked HPB PTFE filters was 96%-100%. The IPPD retention efficiencies on the HPB PTFE filters were 72%-99%, with relative standard deviations indicating the overall reproducibility of 0.9%-3.1%. IPPD on the HPB PTFE filter remained stable for at least 7 days at 4°C. The method quantitation limit was 12.5 μg/sample.

Conclusions: We successfully developed a method to measure workers' exposure to airborne IPPD within the concentration range of 0.05-4 mg/m3, which will assist risk assessments.

Objectives: Many chemicals have been used for industrial purposes, and some of them are carcinogenic to humans. However, the molecular mechanisms of their carcinogenetic effects have not been well understood. Reactive oxygen species are generated from industrial chemicals and contribute to carcinogenesis. Particles and fibers are accumulated in respiratory systems by inhalation exposure and cause chronic inflammation. Under inflammatory conditions, reactive nitrogen species are generated from inflammatory and epithelial cells. These species cause oxidative and nitrative DNA damage, leading to carcinogenesis. We carried out experiments on DNA damage induced by various industrial chemicals and investigated their molecular mechanisms.

Methods: We examined oxidative DNA damage induced by industrial chemicals using DNA fragments derived from human cancer-relevant genes by polyacrylamide gel electrophoresis. Using immunohistochemistry and immunocytochemistry we also examined the formation of 8-nitroguanine (8-nitroG), a DNA lesion formed under inflammatory conditions, in lung tissues and cultured cells exposed to industrial chemicals.

Results: Benzene and o-toluidine metabolites caused oxidative damage to DNA fragments in the presence of Cu(II). H2O2 and Cu(I) were generated during oxidation of these chemicals and involved in DNA damage. 8-NitroG formation was observed in lung tissues of asbestos-exposed mice and humans. Carbon nanomaterials and indium compounds induced 8-nitroG formation in human lung epithelial cells via the release of damage-associated molecular patterns from exposed cells.

Conclusions: Various industrial chemicals are considered to induce carcinogenesis by causing oxidative and nitrative DNA damage. These findings provide an insight into risk assessment of industrial chemicals and prevention of carcinogenesis in workplaces.

Objectives: Limited empirical data are available regarding the safety of self-employed workers in Japan. This study investigated the associations between working hours, income, and work-related injuries among freelancers.

Methods: A cross-sectional study was conducted using data from an internet survey conducted in 2022. Self-employed individuals who did not work as employees or earn an income from their employment were recruited. Work-related injuries, working hours, and annual income were assessed using self-reported questionnaires. Prevalence ratios (PRs) of injury were estimated using modified Poisson regression models, while controlling for covariates. Additionally, PRs were analyzed for each stratum of working hours and income levels.

Results: In total, 1856 freelancers met the eligibility criteria and were included in the study. Among them, 222 (12.0%) experienced at least 1 work-related injury. A significantly higher risk of injury was observed among those working long hours (≥60 h/wk: PR = 1.65; 95% CI, 1.16-2.34; P = .005) and those in the second-lowest income bracket (¥2 to <¥4 million: PR = 1.43; 95% CI, 1.05-1.94; P = .024). Furthermore, several strata exhibited significantly higher PRs, particularly among workers with high incomes who also worked long hours (≥60 h/wk).

Conclusions: Long working hours, particularly exceeding 60 h/wk, are associated with a significantly higher risk of work-related injuries among freelancers. Additionally, 2 high-risk groups were identified based on the combination of working hours and income levels: those with relatively low incomes, and high-income earners who also worked extended hours.

Objectives: This longitudinal study examined the associations of workplace loneliness with job turnover at 6-month follow-up among Japanese full-time employees.

Methods: This study employed a 6-month prospective design as part of the Employee Cohort Study in Japan. Data from wave 15 (February 2024; baseline, T1) and wave 16 (August 2024; follow-up, T2) were used. Only participants who were employed at baseline and completed the follow-up survey were included in the analysis. Workplace loneliness at T1 was measured using 3 scales: the Loneliness at Work Scale (LAWS), a single-item workplace loneliness scale, and a 3-item scale developed by modifying the short UCLA (University College, Los Angeles) Loneliness Scale for workplace loneliness. Job turnover at T2 was defined based on responses indicating either leaving a job or moving to a different company within the preceding 6 months. Multivariable logistic regression analysis assessed the association between workplace loneliness and job turnover, adjusting for sociodemographic variables.

Results: In total, 706 employees who were employed at baseline were included in the analysis. Observed turnover at follow-up was n = 47 (6.7%). Participants who experienced turnover had significantly higher baseline scores for LAWS and the 3-item scale (P = .044 and P = .012, respectively). In the multivariable logistic regression, all 3 workplace loneliness scales demonstrated similar and significant associations with turnover at follow-up.

Conclusions: Workplace loneliness leads to job turnover. Further research is needed to address the generalization and explore mechanisms of the present findings.