Shunichi Araki

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.

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.

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

The Prevalence and Correlates of Occupational Injuries in Small‐Scale Manufacturing Enterprises: Akinori Nakata, et al. National Institute of Occupational Safety and Health—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.

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.

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

OBJECTIVEnPsychosocial 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.nnnMETHODSn1944 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.nnnRESULTSnOverall, 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.nnnCONCLUSIONSnWe conclude that SB is weakly associated with some aspects of job stress in men but not in women among the Japanese working population.