Job stressors and long-term sick leave due to depressive disorders among Japanese male employees: findings from the Japan Work Stress and Health Cohort study.

BACKGROUND: Research on the association between job strain or other job stressors and depressive disorders is still limited. The purpose of the present study was to investigate the prospective association of job strain, role stressors and job insecurity with long-term sick leave due to depressive disorders. METHODS: A prospective study was conducted of a total of 15 256 men aged 18-67 years with no previous history of mental disorders employed in six manufacturing factories located in several regions of Japan. At baseline, they were surveyed using a self-administered questionnaire, including self-reported measures of job strain, as well as its components (job overload and job control), role stressors (role ambiguity and role conflict), social support at work, job insecurity and other demographic and psychological covariates. During the follow-up, a long-term sick leave of 30 days or more due to depressive disorders was recorded. RESULTS: During 5.14 years of follow-up on average, 47 incident cases of sick leave of 30 days or more due to depressive disorders were observed. High job control at baseline was associated with a lower risk of long-term sick leave due to depressive disorders, after adjusting for demographic variables, depressive symptoms and neuroticism at baseline (hazard ratio 0.28, 95% CI 0.11 to 0.71); high role ambiguity was associated with the higher risk (hazard ratio 3.49, 95% CI 1.43 to 8.49). CONCLUSION: Job control and role ambiguity may be important predictors of long-term sick leave due to depressive disorders among male employees, independent of depressive symptoms and neuroticism.

Suicide mortality of young, middle-aged and elderly males and females in Japan for the years 1953-96: time series analysis for the effects of unemployment, female labour force, young and aged population, primary industry and population density.

Effects of nine social life indicators on age-adjusted and age-specific annual suicide mortality of male and female Japanese population in the years 1953-96 were investigated by multiple regression analysis on time series data. Unemployment rate was significantly related to the age-adjusted mortality in both males and females. Also, female labour force participation was positively related to the male mortality; persons and 65 and above was inversely related to the male mortality. Results on the age-specific mortality indicated that: during the 44 yr, (1) unemployment significantly related with the mortality of young, middle-aged and elderly males and young females; (2) female labour force participation significantly related with the mortality of young and elderly males and young females; aged population significantly related with the mortality of middle-aged and elderly males; (4) young population significantly related with the mortality of young and middle-aged males and females; (5) divorce significantly related with the mortality of middle-aged and elderly males and young males and females; (6) persons employed in primary industries significantly related with the mortality in middle-aged males and young males and females; and (7) population density significantly related with the mortality of middle-aged males and young females.

Association of active and passive smoking with sleep disturbances and short sleep duration among japanese working population.

BACKGROUND: The relationship between passive smoking and sleep is uncertain. PURPOSE: To examine the association of passive/active smoking with sleep disturbances. METHOD: 732 women and 1,896 men, working in a suburb of Tokyo, were surveyed using a self-administered questionnaire. Information on smoking, passive smoking exposure, and sleep was elicited. Exposure levels to passive smoking were assessed separately at work and at home as no, occasional, or regular exposure. Risk of sleep disturbances according to smoking status was estimated using logistic regression with odds ratios (OR) and 95% confidence intervals (CIs) as measures of association. RESULTS: Compared to never smokers, odds of difficulty awakening in the morning (DAM) in current smokers were significantly higher for women (OR 1.95) and men (OR 1.50), while increased difficulty initiating sleep (OR 1.88) and decreased early morning awakening (OR 0.31) were found only in women. Never smoking men occasionally exposed to passive smoking at work but not at home had increased odds (OR 1.81) of short sleep duration (SSD, < 6 h) than unexposed counterparts. CONCLUSIONS: The analyses suggest that exposure to passive smoking at work is associated with SSD in men, while current smoking relates to various subtypes of sleep disturbances in both sexes.

Perceived psychosocial job stress and sleep bruxism among male and female workers.

OBJECTIVE: Psychosocial job stress has been associated with sleep disturbances, but its association with sleep bruxism (SB), the stereotype movement disorder related to sleep, is not well understood. The aim of this epidemiological study was to examine the relationship between psychosocial job stress and SB. METHODS: 1944 male and 736 female factory workers participated in this study (response rate 78.1%). Perceived job stress was evaluated with the Japanese version of the generic job stress questionnaire, which covered 13 job stress variables. SB was assessed by the question, 'Do you grind or clench your teeth during your sleep or has anyone in your family told you that you grind your teeth during your sleep?' Response options were 'never', 'seldom', 'sometimes' or 'often'. SB was considered present if the answer was 'sometimes' or 'often'. RESULTS: Overall, 30.9% of males and 20.2% of females reported SB. In males, workers with low social support from supervisors [odds ratio (OR) = 1.34, 95% confidence interval (CI) 1.08-1.68] or from colleagues (OR 1.47, 95% CI 1.17-1.83), and high depressive symptoms (OR 1.60, 95% CI 1.26-2.03) had a significantly increased risk of SB after controlling for confounders. By contrast, no significant association was found in females. CONCLUSIONS: We conclude that SB is weakly associated with some aspects of job stress in men but not in women among the Japanese working population.

Job strain and smoking cessation among Japanese male employees: a two-year follow-up study.

The purpose of the present study was to assess the association between job strain and smoking cessation among Japanese male employees. In 1997, a baseline questionnaire was given to 2,625 (2,113 males and 512 females) employees of an electronics firm in Gifu Prefecture, Japan. The self-administered questionnaire was a set of questions on smoking habits and consisted of items on socio-demographic variables and smoking habits, including the Japanese version of the Job Content Questionnaire (JCQ). The JCQ consists of scales of job control, job demand, supervisory support, coworker support, job insecurity, physical demands, and isometric load. A total of 733 male smokers were then followed for 2 years, with 446 completing a follow-up questionnaire in 1999 (follow-up rate, 61%). Logistic regression analyses were performed to examine associations between job strain and smoking cessation. Among the 446 participants, 38 had quit smoking. After adjusting for age ((odds ratio: OR) = 0.38, 95% (contidence interval: CI) = 0.15-0.94), men with a high level of physical demands at baseline showed a lower smoking cessation rate at follow-up than did those with a low level. However, when adjustments were made for age and other socio-demographic variables, the odds ratio of smoking cessation showed marginal significance (OR = 0.45, 95% CI = 0.16-1.29). There was no significant association between other job strain variables and smoking cessation at the 2-year follow-up. No significant association was found between job strain and change in the number of smoked cigarettes per day. The present study did not support the hypothesis that higher levels of job stressors are associated with a lower rate of smoking cessation among men.

Blood manganese concentrations and intrauterine growth restriction.

To assess the relationship between blood concentrations of manganese (Mn) and intrauterine growth restriction (IUGR), Mn levels in the umbilical cord blood (UCB) and the mother whole blood (MWB) samples were measured in apparently healthy mothers and their newborns. Measurement was conducted by an inductively coupled plasma mass spectrometry. Manganese concentrations in MWB were significantly lower (p<0.01) in IUGR cases than in appropriate for gestational age (AGA) cases (mean+/-S.D.; 16.7+/-4.8 and 19.1+/-5.9 microg/l, respectively). Conversely, UCB concentrations of Mn were significantly higher (p<0.05) in IUGR newborns than AGA newborns (44.7+/-19.1 and 38.2+/-13.1 microg/l, respectively). Logistic regression analysis demonstrated significant relationships of the mother whole blood and the umbilical cord blood concentrations of Mn in IUGR cases (OR=0.868, 1.044, respectively). The study suggests that manganese concentrations in MWB and UCB might induce different effects on birth weight in healthy mothers. Because intrauterine growth restriction is a multi-factorial problem, further epidemiological and clinical studies on larger numbers of subjects are needed to confirm the findings in the present study.

Perceived job stress and sleep-related breathing disturbance in Japanese male workers.

To examine the association of job stress with sleep-related breathing disturbance (SBD), a cross-sectional sample of 1940 males aged 17-83 (mean 45) years in 292 small and medium-sized enterprises in Japan were surveyed by means of a self-administered questionnaire. Perceived job stress was evaluated by the Japanese version of the Generic Job Stress Questionnaire developed by the US National Institute for Occupational Safety and Health, which included 13 job stress variables. Participants were divided into thirds according to their job stress scores. SBD was assessed by the question "Have you ever felt difficulty breathing during sleep or has anyone in your family told you that you have such difficulty?" SBD was defined as presence of symptoms more than once a month. Risk of SBD through job stress was estimated using logistic regression with odds ratios (ORs) and 95% confidence intervals (CIs) as measures of association. Prevalence of study-defined SBD was 6.7%. Participants who perceived the lowest level of social support from supervisors, and highest levels of job future ambiguity, interpersonal conflict at the workplace, job dissatisfaction, variance in workload, and quantitative workload had significantly increased risk of SBD after adjusting for potential confounders. High depressive symptoms, as measured by Center for Epidemiologic Studies Depression scale scores of 16 or higher, were also significantly associated with increased SDB. Although the results should be considered preliminary because of the self-reporting and cross-sectional design, data suggest that exposure to high job stress could be a possible risk factor for developing or aggravating SBD. Results also indicate that job stress should be considered when evaluating SBD in occupational and clinical settings.

Relationship between cumulative effects of smoking and memory CD4+ T lymphocyte subpopulations.

Previous studies have found that smoking is a strong factor that increases peripheral blood CD4+ T lymphocytes. However, most studies did not assess the cumulative long-life exposure of smoking on differential lymphocyte populations. In this study, to clarify the association of smoking habits and circulating lymphocytes, we conducted a cross-sectional study of 60 male current smokers. Smoking status was estimated by number of cigarettes smoked per day, smoking years, and Brinkman Index (BI) as calculated by multiplying the number of cigarettes smoked per day by the smoking years. Counts of CD4+CD45RO+CD69+ T and CD4+CD45RO+ T lymphocytes were strongly and positively correlated with BI and remained highly significant after controlling for alcohol drinking, leisure-time physical activity, and caffeine intake (r(p)>.465, p<.001). These lymphocytes were also significantly correlated with the number of cigarettes smoked per day and smoking years, but the association was weaker than the BI. The findings suggest that the CD4+CD45RO+CD69+ T and CD4+CD45RO+ T lymphocytes are sensitive to cumulative effect of smoking, and may serve as a potential immuno-biomarker for active smoking.

Decreases in CD8+ T, naive (CD4+CD45RA+) T, and B (CD19+) lymphocytes by exposure to manganese fume.

To examine the effects of exposure to manganese (Mn) on the cellular and humoral immune system in men, T lymphocyte subpopulations, B (CD19+) lymphocytes, natural killer (NK) cells, and serum immunoglobulins (i.e., IgG, IgA and IgM) together with total T (CD3+) lymphocytes and total lymphocytes were measured in blood samples from 21 welders mainly exposed to Mn fume with blood Mn (BMn) concentrations of 0.6-2.3 (mean 1.4) microg/dl and 21 healthy controls working in the same factory (BMn concentrations: 0.7 to 1.7, mean 1.1 microg/dl). The workers engaged in welding for 6 to 36 (mean 17) yr. All the study subjects were divided into 3 equally sized groups (n=14 for each group) according to BMn concentrations. Numbers of CD8+ T, total T (CD3+), B (CD19+), and total lymphocytes were significantly lower in high-BMn group than those in low-BMn group; the numbers of CD8+ T lymphocytes were significantly lower in moderate-BMn group compared to low-BMn group. After adjusting for age and smoking, significant inverse correlations between BMn concentrations and CD4+CD45RA+ T, CD4+ T, CD8+ T, CD3+ T, and total lymphocytes were found. We conclude that T lymphocytes, especially CD8+ and CD4+CD45RA+ T lymphocytes, as well as CD19+ B lymphocytes are affected by exposure to Mn fume.

The prevalence and correlates of occupational injuries in small-scale manufacturing enterprises.

Workers involved in small-scale manufacturing businesses are known to comprise a high-risk population for occupational injury. The present study investigated the prevalence and correlates of occupational injury in this population. A self-administered questionnaire that solicited answers about occupational information including injury, demographic characteristics, health conditions and lifestyle factors was collected from a sample of 1,298 workers in 228 small-scale manufacturing enterprises (defined as fewer than 50 workers) aged 16-78 (mean 46) yr in Yashio city, Saitama, Japan (response rate 65.5%). The enterprises were randomly selected from the 2000 edition of the city commercial directory corresponding to the distribution of types of businesses in the city. Occupational injury was assessed by asking subjects, ;Have you ever been injured during your work, including minor scratches and cuts in the previous 1-yr period?' The possible response was either ;yes' or ;no.' The prevalence of study-defined occupational injury among the workers was 35.6% (male 43.0%, female 17.9%). Among job types, manufacturing (44.2%) and driving (43.5%) had high rates of occupational injuries. Similarly, occupational injuries were high in the papermaking (54.5%) and machinery (47.7%) industries. For males, younger age, current or former smoking, insomnia symptoms, and disease(s) currently under treatment were correlated with injury, whereas for females, being unmarried, higher educational status, and insomnia symptoms were the correlating factors. Occupational injury is common among small-scale manufacturing businesses, and is associated with multiple controllable factors. Countermeasures such as prohibiting smoking during work, sleep health education, job safety training for young/inexperienced workers are appropriate methods for eliminating or reducing injuries.

Non-fatal occupational injury among active and passive smokers in small- and medium-scale manufacturing enterprises in Japan.

Active smoking is a risk factor for occupational injury, whereas its association with passive smoking is unknown. To evaluate the contribution of active and passive smoking to non-fatal occupational injury in manufacturing sectors, 2302 randomly selected workers aged 16-83 years working in 244 small- and medium-scale enterprises in Yashio city, Japan, were surveyed by means of a self-administered questionnaire. Smoking history, exposure to passive smoking, and occupational injury were evaluated by self-report. Exposure levels to passive smoking were assessed separately at work and at home as never, occasional, or regular exposure. Overall, 61.4% of men and 22.3% of women were current smokers. Among never smokers, 62.2% of men and 68.6% of women reported exposure to passive smoking either at work or home. Prevalence of occupational injuries was 36.2% for never, 43.3% for former, and 41.2% for current smokers among men and 19.7% for never, 22.2% for former, and 25.2% for current smokers among women. Among never smoking men, odds ratios (ORs) of occupational injury were 2.11 when regularly exposed to passive smoking at work or at home (p=0.025), 2.27 at work (p=0.015), and 3.08 at home (p=0.106), in comparison to never smoking men who were never exposed to passive smoking either at work or at home (referent group). These associations were attenuated to be non-significant, after controlling for potential confounders. Never smoking men with occasional exposure to passive smoking were not significant ORs (1.11-1.19). In contrast, current and former smoking men had significant increases in adjusted ORs (1.57-2.00). In women exposed to smoking there was a non-significant increase in occupational injury. The present study indicates an expected increase in the risk of, occupational injury for current and former smoking men and suggests that exposure to passive smoking is a possible risk factor for never smoking men.

Impact of psychosocial job stress on non-fatal occupational injuries in small and medium-sized manufacturing enterprises.

BACKGROUND: Workers involved in manufacturing are known to comprise a high-risk population for occupational injury, and this risk is greater in small and medium-sized enterprises (SMEs). The purpose of this study was to examine the association between psychosocial job stress and occupational injuries among workers in SMEs. METHODS: One thousand forty-nine men and 721 women from 244 SMEs participated in this study. Perceived job stress was evaluated with the Japanese version of the generic job stress questionnaire, which covered 14 job stress variables. Occupational injury was assessed by self-report during the last 1-year period. RESULTS: Workers with high quantitative workload (odds ratio [OR] = 1.55 for men, 1.62 for women), high cognitive demands (OR = 1.70 for men, 1.53 for women), and low job satisfaction (OR = 1.33 for men, 1.93 for women) had a significantly increased risk of occupational injury in the multivariate model. High variance in workload (OR = 1.70) and high job future ambiguity (OR = 1.35) in men, and low job control (OR = 2.04) and high intragroup conflict (OR = 1.66) in women were significantly associated with occupational injury. In manufacturing/production workers, high quantitative workload (OR = 1.91), high variance in workload (OR = 2.02), and high depressive symptoms (OR = 1.55) were significantly associated with injury in men, while low social support from colleagues (OR = 2.36) or family (OR = 2.51) was related to injury in women. CONCLUSIONS: These data point to an independent relationship between psychosocial job stress and self-reported occupational injury in SMEs.

Job strain, worksite support, and nutrient intake among employed Japanese men and women.

BACKGROUND: The association of job strain (as defined by the job demands/control model) and worksite support with nutrient intake is not clear. METHODS: A questionnaire survey was conducted of 25,104 workers employed in nine companies in Japan. Job strain and worksite support were assessed using the Job Content Questionnaire. Daily intake of 17 nutrients was measured using a dietary history questionnaire. Data from 15,295 men and 2,853 women were analyzed, controlling for age, education, marital status, occupation, and study site. RESULTS: Among men, job strain was positively associated with average daily intakes of fat, vitamin E, cholesterol, poly- and mono-unsaturated fatty acids (p for trend<0.05), and worksite support was positively associated with average daily intakes of total energy, crude fiber, retinol, carotene, vitamins A, C, and E, cholesterol, and saturated fatty acid (p for trend<0.05). Among women, worksite support was positively associated with average daily intakes of total energy, protein, vitamin E, and polyunsaturated fatty acid (p for trend<0.05). However these differences were generally small. CONCLUSIONS: The present study showed that job strain and worksite support were only weakly and inconsistently associated with nutritional intakes. It does not seem that changes in nutritional intakes explain the association between job strain or worksite support and coronary heart disease.