Silicosis is a fibrotic lung disease produced by the inhalation and deposition of silica dust. The association between silicosis and pulmonary tuberculosis (PTB) has been well established. Cytokines participate in the development and progression of silicosis and PTB. Functional polymorphisms in cytokine genes have been identified that alter cytokine production. The aims of the current investigation were to determine whether functional polymorphisms in the tumor necrosis factor-alpha (TNF-α) gene at position -308; in the transforming growth factor-beta 1 (TGF-β1) gene at positions -509, +869 (codon 10), and +915 (codon 25); in the interleukin-10 (IL-10) gene at position -1,082, -819 and -592; and in the intron 1 of the interferon-gamma (IFN-γ) gene at position +874 are associated with silicosis and PTB. We conducted a case-control study with 183 silicosis patients and 111 silica-exposed miners, and a 1:2 matched case-control study of 61 PTB cases and 122 PTB-free miners. Genotype analysis was performed on genomic DNA, using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay. There was complete linkage disequilibrium (LD) between the -819C and -592C alleles of the IL-10 gene. The genotype frequencies were similar between cases and control subjects for all investigated cytokine polymorphisms (p>0.05). We did not find an association between the different genotypes and severity of silicosis. We assume that these genetic variants do not play a dominant role in silicosis and PTB in our Chinese population.

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The Mental Health Action Checklist for a Better Workplace Environment (MHACL) is a tool for a worker participatory approach to improve work environments for worker mental health. The present study investigated the effects of an organizational intervention using the MHACL on reducing job stressors and the psychological distress of workers of a manufacturing enterprise in Japan with a controlled study design. Nine of 45 departments participated in a work environment improvement program, including planning workshops, implementation and monitoring, between July and December 2005 (intervention group, n=321). The remaining 36 departments served as the control group (n=750). Outcomes (job stressors, worksite support, psychological distress, etc.), measured using the Brief Job Stress Questionnaire, as well as sick leave days taken from the company record, were recorded before and six months after the program for both groups. Among women, skill underutilization, supervisor and coworker support, psychological distress, and job satisfaction changed more favorably in the intervention group than in the control group (p<0.05). No significant favorable effect of the program was observed among men. Improvements in the outcomes were more prominent among departments with a 50% or higher rate of worker participation in the planning workshops and among departments with a 50% or higher rate of implemented vs. planned actions. A worker participatory organizational intervention using the MHACL seems effective for promoting mental health among Japanese white-collar women.

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Indium is widely used in the electronics industry to make semiconductors, liquid-crystal panels, and plasma display panels, and its production is increasing. However, it is necessary to handle it more cautiously than before, because the pulmonary toxicity of inhaled indium has been identified. The present study aimed to characterize the potential toxic effects of indium through oral administration and observation for fourteen days following a single dose of 0 or 2,000 mg/kg (acute oral toxicity study), and repeated oral administration for 28 days at dose levels of 0, 40, 200, or 1,000 mg/kg daily (28-day repeated oral dose toxicity study) to male and female Crj:CD (SD) IGS rats (SPF). No deaths and no abnormalities in clinical signs, body weights, and necropsy findings were observed for any of the animals in the acute oral toxicity study. Furthermore, no changes related to indium were also observed in the dose groups up to 1,000 mg/kg of the 28-day repeated oral dose toxicity study. From the results described above, the lethal dose 50% (LD₅₀) of indium is greater than 2,000 mg/kg under these study conditions, and the no-observed-adverse-effect-level (NOAEL) is considered to be 1,000 mg/kg for males and females under these conditions.

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This study aimed to test the psychometric properties of the Thai version of the Effort-Reward Imbalance Questionnaire (T-ERIQ). The English version of the 23-item ERIQ was translated and back-translated. Content validity was examined by five experts and face validity was examined by twelve key informants before being tested for construct validity with 828 workers from six garment factories. Predictive validity was assessed through the relationship between the ERI constructs and psychological health outcomes including psychosomatic symptoms, state of anxiety, depression, and job satisfaction. The internal consistency of the Thai ERIQ was tested using the first survey (n=828), and test-retest stability was examined 2 to 4 wk later with a subsample (n=408). The results show that 2% of workers reported effort-reward imbalance (ERI ratio≥1). The Thai ERIQ has good content validity with a Content Validity Index of 0.95. Cronbach's alpha coefficients for the effort, reward, and overcommitment scales were 0.77, 0.81, and 0.66, respectively. The 2-4 wk stability of these three constructs was moderate (r=0.496-0.576, p<0.001). Overall, the factorial validity was demonstrated as the best model fit, with high values of the goodness-of-fit indices, using confirmatory factor analysis, indicating accordance with the theoretical constructs of the ERI model. Logistic regression analyses supported significant associations of reward with all psychological health outcomes (p<0.05). The findings suggest that the Thai ERIQ has adequate reliability and validity to investigate the psychosocial work environment. The Thai ERIQ can be applied to the Thai working population, particularly industrial manufacturing workers.

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Fly ash and ambient emissions of municipal solid waste incinerators contain polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polycyclic aromatic hydrocarbons (PAHs), other organic compounds, metals, and gases. Hazardous substances such as PCDD/Fs, mercury vapors and other silicates, and the components of bottom ash and fly ash elevate the oxidative damage. We compared oxidative damage in workers exposed to hazardous substances at a bottom ash recovery plant and 3 fly ash treatment plants in Taiwan by measuring their levels of plasma malondialdehyde (MDA) and urine 8-hydroxydeoxyguanosine (8-OH-dG). Significantly higher MDA levels were found in fly ash treatment plant workers (3.20 μM) than in bottom ash plant workers (0.58 μM). There was a significant association between MDA levels in workers and their working environment, especially in the fly ash treatment plants. Levels of 8-OH-dG varied more widely in bottom ash workers than in fly ash workers. The association between occupational exposure and 8-OH-dG levels may be affected by the life style of the workers. Because more dioxins and metals may leach from fly ash than from bottom ash, fly ash treatment plant workers should, as much as possible, avoid exposing themselves to fly ash.

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The effort-reward imbalance is an important psychosocial factor which is related to poor health among employees. However, there are few studies that have evaluated effort-reward imbalance among medical residents. The present study was done to determine the association between psychosocial factors at work as defined by the effort-reward imbalance model and depression among Japanese medical residents. We distributed a questionnaire to 227 medical residents at 16 teaching hospitals in Japan at the end of August 2005. We asked participants to answer questions which included demographic information, depressive symptoms, effort-reward imbalance, overcommitment and social support. Depression was evaluated using the Japanese version of the Center for Epidemiologic Studies-Depression (CES-D) scale. The effort-reward imbalance and overcommitment were assessed by the Effort-Reward Imbalance (ERI) questionnaire which Siegrist developed. Social support was determined on a visual analog scale. Logistic regression analysis was performed to determine the associations between effort-reward imbalance and depressive symptoms. Depressive symptoms were found in 35 (29.2%) 1st-year residents and 21 (27.6%) 2nd-year residents. The effort-reward ratio >1 (OR, 8.83; 95% CI, 2.87-27.12) and low social support score (OR, 2.77, 95% CI, 1.36-5.64) were associated with depressive symptoms among medical residents. Effort-reward imbalance was independently related to depression among Japanese medical residents. The present study suggests that balancing between effort and reward at work is important for medical residents' mental health.

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The purpose of this cross-sectional study was to evaluate the quality of life (QOL) of coal dust workers without pneumoconiosis in mainland China. Three hundred five coal dust workers and 200 non-dust workers without pneumoconiosis from five coal mines in Shanxi province were enrolled in this study. The Chinese World Health Organization Quality of Life-brief version (WHOQOL-BREF) questionnaire was used. Socio-demographic, working, and health factors were also collected. Multiple stepwise regression analysis was used to identify significant factors related to the four domain scores of WHOQOL-BREF. All functional domains of the Chinese WHOQOL-BREF were significantly worse in coal dust workers compared to non-dust workers except for psychological health. For the physical domain of QOL, educational level, working hours, and work danger were the significant factors. In the psychological domain, types of job, welfare satisfaction, work danger, hobbies, smoking, one-child family, and marital status were the predictive factors. Working hours, welfare satisfaction, educational level, and birthplace were the predictive factors for the social domain of QOL. Finally, the predictors for the environmental domain of QOL were types of job, working hours, welfare satisfaction, work danger, self-reported social status, smoking, and drinking. Coal dust workers without pneumoconiosis had worse QOL than non-dust workers but their subjective feelings were positive. There were four distinct models for the various domains of QOL. Corresponding health policies could be developed to improve their QOL.

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Cardiac strain was evaluated in terms of working heart rate (WHR), relative cardiac cost (RCC), net cardiac cost (NCC) and other recovery indices among six younger (mean age 34.2 ± 2.7 yr) and sixteen older (mean age 48.9 ± 5.4 yr) drillers working in a manual underground coal mine over two spells of work. The mean WHR was within the range of 117-132 beats / min with corresponding mean relative cardiac cost between 44-48% of heart rate reserve for the younger group and 53-55% for their older counterparts. The mean NCC was above 50 beats/min for both age groups. It was seen that the workers surpassed the recommended limits of cardiac strain indices. The intensity of workload indicates the job to be "heavy" to "extremely heavy" in accordance with the heaviness scales based on WHR, NCC and recovery heart rates. Heat stress prevailing in the workplace in terms of effective temperature (ET) and wet bulb globe temperature (WBGT), was above the recommended limits as per the guidelines proposed by WHO and ACGIH. High physiological demands of the job which requires predominate static muscular exertions coupled with high heat stress were found to hinder the recovery process and may prove deleterious particularly for the older workers. Therefore, in the present context, the need of ergonomic interventions for job organization and quick reparation of environmental condition are strongly indicted.

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