Journal of Occupational Health最新文献

Objectives: The objective of the current study was to elucidate the relationship between blood cadmium (Cd-B) levels and proximal tubular dysfunction using urinary β2-microglobulin (B2M-U) as an indicator among workers in nickel-cadmium battery plants in Japan.

Methods: Medical check-up data from 338 workers exposed to cadmium at 2 plants were collected from 1997 through 2020. Workers with at least 2 check-ups were included, excluding those with other renal dysfunctions. Proximal tubular dysfunction was defined as a B2M-U of 300 μg/g creatinine or higher in 2 or more consecutive check-ups. A multivariable Cox proportional-hazards regression model with time-dependent covariates was performed to analyze the relationship between Cd-B levels and the time to onset of proximal tubular dysfunction, adjusting for age, sex, and smoking history.

Results: Of the 338 workers, 238 met the study eligibility criteria for the analyses. The geometric mean of Cd-B was 1.97 μg/L. The Cox proportional hazards analysis demonstrated that higher time-dependent Cd-B levels were significantly associated with an increased risk of proximal tubular dysfunction, with a hazard ratio of 1.17 (95% CI: 1.06-1.29).

Conclusions: Higher Cd-B levels are associated with an increased risk of proximal tubular dysfunction in workers exposed to cadmium, indicating an increased risk of renal disease under the current industrial health management in Japan. Continuous monitoring and improved management of cadmium exposure are necessary to protect workers' health even in developed countries such as Japan.

Objectives: Our aim was to report integrative evidence for the health risk assessment of ortho-toluidine (OT) in bladder cancer in a mini-review of the recent studies of humans, experimental animals, and OT skin permeability.

Methods: Bladder cancer cases were identified in workers in Japan who were occupationally exposed in 2014-2017 to aromatic amines, primarily to the human carcinogen OT.

Results: A key epidemiological study of 98 aromatic amine-exposed workers in Japan showed a clear OT exposure-response relationship with a standardized incidence ratio. A rat model experimental study also indicated that OT and acetoaceto-o-toluidine are potent bladder carcinogens. Multiple mechanisms of OT-related bladder cancer have been proposed: metabolic activation to reactive metabolites that bind DNA and proteins, mutagenicity, oxidative DNA damage, chromosomal damage, and cytotoxicity by OT. Recent comprehensive analyses of DNA adducts in rats identified a number of common oxidative DNA adducts, including 8-OHdG, in the rat urothelium and indicated that oxidative stress may play a crucial role in the development of urinary cancer caused by OT. The skin permeability of 6 aromatic amines (o-toluidine, aniline, p-toluidine, o-anisidine, 2,4-dimethylaniline, and o-chloroaniline) was examined with the use of a 3-dimensional (3D) reconstructed human skin model; ~70%-80% of the 6 aromatic amines had permeated through the 3D skin within 8 hours. Genotoxic potency testing in a human urothelial cell line using γ-H2AX, a marker of DNA damage, suggested that OT exhibited strong γ-H2AX generation.

Conclusions: Prolonged dermal exposure to OT along with other genotoxic aromatic amines over many years may contribute to the development of bladder cancer.

Objectives: This study aimed to investigate the impact of perceived workplace health support (PWHS) on absenteeism and presenteeism among Japanese workers to determine the significance of health and productivity management in improving labor productivity.

Methods: This prospective cohort study, using data from the Work Systems & Health Internet Research (WSHIR) study, involved 1879 Japanese workers aged 20-69 years. The intensity of PWHS was assessed using self-administered questionnaires. The participants were followed up from October 2021 to October 2022 to evaluate the incidence of absenteeism and presenteeism based on the level of PWHS.

Results: The study findings revealed that higher PWHS significantly correlated with lower presenteeism, indicating better work productivity. Conversely, the relationship between PWHS and absenteeism was less clear, with no consistent trend observed across different levels of PWHS intensity.

Conclusions: Enhanced PWHS was associated with reduced presenteeism among Japanese workers, underscoring the importance of workplace health support for improving employee productivity. This finding emphasizes the need for companies to focus on health promotion activities and recognize the potential of PWHS as a performance indicator in corporate health management.

Objectives: Previous research has indicated that shift workers exhibit fewer healthy behaviors than those working regular daytime hours. Although health literacy influences health behaviors, studies comparing health literacy levels between shift and fixed-day workers and investigating whether differences in health behaviors between these 2 groups are mediated by health literacy are lacking.

Methods: This cross-sectional study used a self-administered questionnaire in a large-scale manufacturing company. Overall, 2152 manual workers aged 18-64 years were enrolled in this study (961 and 1191 fixed-day and shift workers, respectively). Logistic regression structural equation models were used for analyzing the mediating role of health literacy in the relationship between shift work and health behaviors.

Results: Shift and fixed-day workers did not show differences in age-adjusted health literacy. Compared with fixed-day workers, the odds ratios of shift workers for leisure time exercise, not currently smoking, having breakfast, brushing their teeth, and eating green and yellow vegetables were 0.85 (95% CI, 0.70-1.02), 0.68 (95% CI, 0.56-0.80), 0.63 (95% CI, 0.52-0.76), 0.79 (95% CI, 0.65-0.95), and 0.58 (95% CI, 0.48-0.70), respectively. Mediation analysis showed that the odds ratios of the direct effects of shift work on favorable habits were almost the same as the total effect.

Conclusions: This study observed that health literacy did not mediate health behavior and shift work. Further research is needed to clarify the causes of these differences.

Background: Self-rated health is a comprehensive measure of health status that may influence occupational accidents, particularly those involving human factors. This study aimed to examine the relationship between self-rated health and occupational accidents across various industries and occupations. We also investigated the relationship stratified by the type of accidents.

Methods: We conducted a prospective cohort study using online self-administered questionnaires targeting workers in Japan. A baseline survey was conducted in March 2022, followed by a 1-year follow-up survey. Self-rated health at baseline was categorized into 4 groups: very good/good, slightly good, slightly poor, and poor/very poor. The dependent variable was the occurrence of occupational accidents and types of occupational accidents during the follow-up period. Logistic regression analyses adjusted for covariates were used to calculate odds ratios (ORs) and 95% CIs. We also performed trend tests and calculated P for trend.

Results: The analysis included 15 744 participants, among whom 1534 experienced workplace accidents. Compared with the very good/good group, the ORs for occupational accidents were 1.37 (95% CI, 1.21-1.56) in the slightly good group, 2.41 (95% CI, 2.07-2.80) in the slightly poor group, and 3.67 (95% CI, 2.94-4.59) in the poor/very poor group. Trend tests revealed significant associations between self-rated health and injuries from falls, injuries from cutting and rubbing, and heat stroke but not with injuries from crashes or tumbles and injuries from flying or falling objects.

Conclusions: Self-rated health was significantly associated with occupational accidents, particularly those involving substantial human factors.

Objectives: Voice and emotional analyses have gained attention in the diagnosis and monitoring of depression in clinical settings. However, evidence supporting its use for early detection in occupational health is lacking. This study aimed to develop a predictive model to identify early depressive symptoms in workers using voice and emotional analyses.

Methods: A prospective cohort study was conducted with 62 call center workers in Kumamoto Prefecture, Japan. The participants' voices were automatically recorded during routine operations and analyzed using a voice and emotional analysis system based on Layered Voice Analysis. Depressive symptoms were assessed at 4 time points over 12 weeks using the Center for Epidemiologic Studies Depression Scale. Recursive Feature Elimination identified optimal voice features, while logistic regression was used to calculate the probability scores and build a predictive model for depressive symptoms. Predictive accuracy was evaluated using receiver operating characteristic curves and the area under the curve.

Results: The predictive model's accuracy reached 0.783 (95% CI, 0.691-0.875) for the area under the curve, with a sensitivity of 0.649, a 1 - specificity of 0.174, and a cutoff value of 0.334. Individuals with composite voice indicators above the determined cutoff were significantly more likely to exhibit depressive symptoms 1 month later (odds ratio = 7.78; 95% CI, 3.27-18.5).

Conclusions: This study suggests that voice and emotional analysis can serve as an objective tool for the early identification of depressive symptoms in workplace settings. Accumulating real-world evidence from observational studies in diverse occupational populations is required to support broader implementation.

Objectives: Many Japanese adults experience poor sleep quality. Prolonged sedentary behavior negatively affects health, including sleep-associated problems. We investigated the association between sedentary behavior and sleep quality among urban white-collar workers in Japan with metabolic syndrome or at risk of metabolic syndrome, a population thought to have particularly prolonged sedentary time.

Methods: This study was conducted using a prospective cohort study design as a secondary analysis of participants' data in a lifestyle intervention program using a smartphone application in 5 different companies (>1000 employees) in Tokyo from December 2018 to March 2019. The primary outcome was sleep quality, obtained as the daily score of relevant items in the St Mary's Hospital Sleep Questionnaire (SMHSQ) during the study period. The primary exposure was daily sedentary time (hours), which was objectively measured using a wristwatch-type wearable device (Fitbit Versa). Multilevel linear mixed effects analysis adjusted for covariates was used to estimate between-person and within-person associations. Sensitivity analyses were used to investigate between-/within-person associations between sedentary time and the scores of each item related to sleep quality on the SMHSQ.

Results: A longer sedentary time was inversely associated with the SMHSQ scores related to sleep quality in multivariable-adjusted models at the individual level (β coefficient -.046; SE 0.016; 95% CI, -.077 to -.015). Longer sedentary time was also inversely associated with each sleep satisfaction-related SMHSQ item. However, no significant associations were observed at the population level.

Conclusions: Longer sedentary time was inversely associated with sleep quality at the individual level.

Objectives: To examine the utility of the FIB-3 index as a secondary screening tool for liver fibrosis in workplace-based health checkups, by comparing its concordance and negative predictive values (NPVs) with those of the FIB-4 index.

Methods: This cross-sectional study included 12 622 workers from the Hitachi Cohort Study who underwent workplace-based health checkups between April 2021 and March 2022. FIB-4 was calculated using age, aspartate aminotransferase (AST), alanine aminotransferase (ALT), and platelet count, whereas FIB-3 used the same components except age. To evaluate the utility of FIB-3 in excluding liver fibrosis, NPVs were calculated using FIB-4 thresholds (1.30, 2.01, and 2.67) as references. Concordance between FIB-3 and FIB-4 was examined across different age groups. In addition, multivariate logistic regression analysis was conducted to identify factors associated with false-positive FIB-3 results.

Results: The FIB-3 index demonstrated high NPVs for excluding liver fibrosis, with values of 99.9% at FIB-4 ≥ 1.30 and 98.2% at FIB-4 ≥ 2.67. Strong concordance between FIB-3 and FIB-4 was observed consistently across different age groups. Among participants with elevated ALT (>30 IU/L), FIB-3 consistently ruled out fibrosis, whereas FIB-4 positivity increased with advancing age. Multivariate analysis indicated that higher AST levels and increased alcohol intake were significantly associated with false-positive FIB-3 results.

Conclusions: The FIB-3 index demonstrated stable performance across age groups while maintaining high concordance and NPV relative to FIB-4. These findings suggest that FIB-3 may serve as a practical screening tool in routine workplace-based health checkups, particularly in mitigating age-related overestimation observed with the FIB-4 index.

Objectives: This study aimed to clarify the primary preventive effects of physical activity interventions delivered through digital health technology (DHT) on workers' mental health symptoms, and to examine the conditions of attrition and adherence in these interventions.

Methods: We examined randomized controlled trials (RCTs) that analyzed the effects of physical activity interventions delivered through DHT on workers' health outcomes. We included RCTs published in English or Japanese since 2010 and excluded studies that targeted specific diseases or secondary and tertiary prevention. We conducted the search on July 25, 2023, using Cochrane CENTRAL, Embase, PsycINFO, PubMed, and Ichushi-Web, and citation searches. We assessed risk of bias using the Cochrane Risk of Bias Tool version 2, and data were integrated using a random-effects model. Attrition rates were averaged, and adherence was qualitatively reviewed.

Results: Eight studies were included in the systematic review, and 5 in the meta-analysis. Pooled effect sizes immediately after intervention were as follows: Cohen d = -0.51 (95% CI, -0.75 to -0.27) for depression and negative affect, and -0.36 (95% CI, -0.60 to -0.05) for perceived stress. The attrition rate was 16.8% and 12.4% for the control and intervention groups, with only 2 studies providing details on adherence.

Conclusions: Physical activity interventions delivered through DHT may moderately improve depression and negative affect, and slightly reduce perceived stress among workers. However, these findings should be interpreted with caution due to the limited number of studies and low evidence certainty. Future studies should explore long-term effects, additional mental health outcomes, and factors affecting adherence.