Kanae Karita

Changes in body mass index by birth cohort in Japanese adults: results from the National Nutrition Survey of Japan 1956–2005

Background The National Nutrition Survey, Japan (NNS-J) provides annual anthropometric information for a whole nation over 50 years. Based on this survey, the mean body mass index (BMI) of Japanese men and elderly women has increased in recent decades, but that of young women has decreased. We examined the effect of birth cohort on this phenomenon. Methods We analysed data from the NNS-J for subjects aged 20–69 years. BMI during 1956–2005 and the prevalence of overweight and obesity (BMI ≥ 25 kg/m2) during 1976–2005 were estimated. Results The BMI increased with age in every birth cohort, with similar increments, and did not peak until 60–69 years of age. However, with cross-sectional age, the BMI usually peaked before 60–69 years of age. The differences among cohorts already existed at 20–29 years of age, and slightly increased in men between 20–29 and 30–39 years of age. The BMI in all male age groups increased from the 1891–1900 through 1971–80 cohorts. However, in women, the figure increased until the 1931–40 cohorts, but later decreased. Changes in prevalence were generally consistent with changes in BMI. The recent increase (decrease in young women) in the mean BMI is attributable to birth cohort, indicating that thinner (fatter) and less recent birth cohorts have been replaced by fatter (thinner) ones. Conclusions A cohort effect was quantitatively demonstrated based on a repeated annual survey. In Japan, the differences in BMI among cohorts were already established by young adulthood.

Respiratory symptoms and pulmonary function among traffic police in Bangkok, Thailand.

Abstract The authors undertook a cross-sectional study of the potential adverse health effects of air pollution in Bangkok, Thailand. During 1998 and 1999, the authors administered lung function spirometry tests and a Thai version of the American Thoracic Societys Division of Lung Diseases (ATS-DLD) respiratory questionnaire to 78 male traffic police and 60 male nontraffic police in Bangkok, as well as to 68 male general police in Ayutthaya province, a rural area in Thailand. No consistent trend of decreased pulmonary function was observed in traffic police. The authors controlled for age, height and smoking index, after which mean levels of forced expiratory volume in 1 sec and maximal expiratory flow rate in 25% of vital capacity ([Vdot]25) were significantly lower in Bangkok police than in Ayutthaya police. The prevalence of respiratory symptoms among Bangkok police was slightly higher than among Ayutthaya police. Multiple regression analysis identified age and workplace as statistically significant factors that contributed to the values of forced expiratory volume in 1 sec and [Vdot]25. This study provided some evidence of an increase in prevalence of obstructive changes in the peripheral airways among traffic police in Bangkok.

Roadside particulate air pollution in Bangkok.

Abstract Airborne fine particles of PM2.5-10 and PM2.5 in Bangkok, Nonthaburi, and Ayutthaya were measured from December 22, 1998, to March 26, 1999, and from November 30, 1999, to December 2, 1999. Almost all the PM10 values in the high-polluted (H) area exceeded the Thailand National Ambient Air Quality Standards (NAAQS) of 120 μg/m3. The low-polluted (L) area showed low PM10 (34–74 μg/m3 in the daytime and 54–89 μg/m3 at night). PM2.5 in the H area varied between 82 and 143 μg/m3 in the daytime and between 45 and 146 μg/m3 at night. In the L area, PM2.5 was quite low both day and night and varied between 24 and 54 μg/m3, lower than the U.S. Environmental Protection Agency (EPA) standard (65 μg/m3). The personal exposure results showed a significantly higher proportion of PM2.5 to PM10 in the H area than in the L area (H = 0.80 ± 0.08 and L = 0.65 ± 0.04). Roadside PM10 was measured simultaneously with the Thailand Pollution Control Department (PCD) monitoring station at the same site and at the intersections where police work. The result from dual simultaneous measurements of PM10 showed a good correlation (correlation coefficient: r = 0.93); however, PM levels near the roadside at the intersections were higher than the concentrations at the monitoring station. The relationship between ambient PM level and actual personal exposures was examined. Correlation coefficients between the general ambient outdoors and personal exposure levels were 0.92 for both PM2.5 and PM10. Bangkok air quality data for 1997–2000, including 24-hr average PM10, NO2, SO2, and O3 from eight PCD monitoring stations, were analyzed and validated. The annual arithmetic mean PM10 of the PCD data at the roadside monitoring stations for the last 3 years decreased from 130 to 73 μg/m3, whereas the corresponding levels at the general monitoring stations decreased from 90 to 49 μg/m3. The proportion of days when the level of the 24-hr average PM10 exceeded the NAAQS was between 13 and 26% at roadside stations. PCD data showed PM10 was well correlated with NO2 but not with SO2, suggesting that automobile exhaust is the main source of the particulate air pollution. The results obtained from the simultaneous measurement of PM2.5 and PM10 indicate the potential environmental health hazard of fine particles. In conclusion, Bangkok traffic police were exposed to high levels of automobile-derived particulate air pollution.

Particulate Air Pollution and Chronic Respiratory Symptoms among Traffic Policemen in Bangkok

In this cross-sectional study, the authors examined the relationship between traffic-based air pollution and chronic, nonspecific respiratory symptoms among traffic policemen in Bangkok, Thailand. A total of 1,603 policemen who lived and worked in areas that had 3 different levels of airborne particulates were evaluated. The authors used a modified standardized questionnaire to identify nonspecific respiratory disease (NSRD) in participants. The prevalence of NSRD in heavily polluted, moderately polluted, and suburban areas was 13.0%, 10.9%, and 9.4%, respectively. Among nonsmokers, the age-adjusted prevalence of NSRD in the heavily polluted areas was significantly higher than in the suburban control area. Also among nonsmokers, the odds ratio for NSRD for each 10-μg/m3 increase in ambient particulate matter was 1.11. The authors concluded that the increased prevalence of respiratory symptoms among traffic policemen in Bangkok was associated with urban traffic air pollution.

Benchmark Dose of Lead Inducing Anemia at the Workplace

To estimate the critical dose of lead inducing anemia in humans, the effects of lead on hemoglobin (Hb) and hematocrit (Hct) levels and red blood cell (RBC) count were examined in 388 male lead-exposed workers with blood lead (BPb) levels of 0.05-5.5 (mean 1.3) micromol/L by using the benchmark dose (BMD) approach. The BPb level was significantly related to Hb (regression coefficient beta=-0.276), RBC (beta=-11.35), and Hct (beta=-0.563) among the workers (p < 0.001) when controlling for age and working status. The average BPb levels were significantly higher in the workers with anemia (1.85 micromol/L), based on the WHO criteria, than in those without anemia (1.26 micromol/L). The benchmark dose levels of BPb (i.e., lower 95% confidence limits of BMD), calculated from the K-power model set at an abnormal probability of 5% in unexposed workers and an excess risk of 5% in exposed workers were estimated to be 0.94 micromol/L (19.5 microg/dl) for Hb, 0.94 micromol/L (19.4 microg/dl) for RBC, and 1.43 micromol/L (29.6 microg/dl) for Hct. These findings suggest that reduction in hematopoietic indicators may be initiated at BPbs below the level currently considered without effect.

Trace elements in human transitory milk : variation caused by biological attributes of mother and infant

Multielement analysis was performed on human milk collected on 5-9-d postpartum from 51 Japanese females using inductively coupled plasma (ICP) mass spectrometry (MS), ICP atomic emission spectrometry (ICP-AES) and fluorometry. Thirty-one elements were detected by these analytical methods in milk. Twelve elements (Na, Mg, P, S, K, Ca, Cu, Zn, Se, Sr, Rb, and Mo) were detected in all of the samples. Al, Cs, and Ba were the elements detected by ICP-MS in more than half of the samples. Multiple regression analysis extracted biological attributes of mother and infant, such as maternal stature, maternal wt, or infants birth wt, as statistically significant factors contributing to the variation in elemental concentration in milk. However, the rates of contribution were small in all cases. It was concluded that the biological attributes of mother and infant examined in this study were not the major factors that contribute to elemental variation in human milk.

Possible oral lead intake via contaminated facial skin

Thirty-six workers exposed to low or moderate levels of lead at low temperature refining processes were surveyed to examine the route of lead intake. Blood lead level (BPb), delta-aminolevulinic acid in urine, lead in facial skin wipes (Face-Pb) and lead in fingernails (Nail-Pb) were measured and their personal hygienic behavior was surveyed by a questionnaire. BPb showed a significant correlation with Face-Pb and Nail-Pb (r = 0.730 and r = 0.590, respectively). Multiple regression analysis extracted the factors of smoking at the workplace, face-Pb and nail-Pb as significantly related to BPb level. Electron-microscopic observation revealed that the majority of dust particles collected from workers faces were larger than respirable size. Lead ingestion from contaminated face skin and fingers may contribute to elevations in the BPb level among workers.

Relationships between Effort-Reward Imbalance, Over-Commitment, and Fatigue in Japanese Information-Technology Workers

Siegrist has suggested that situations in which people believe they have expended high effort, but perceive themselves to have reaped relatively little reward, lead to a state of emotional distress . People’s ability to cope with stress varies, and the effort-reward imbalance (ERI) model can accommodate this. People who are overcommitted will exaggerate their efforts because of their desire for esteem and approval, and will find the discrepancy between effort and reward particularly stressful. Therefore, Siegrist proposed that overcommitment not only results in emotional exhaustion but also exacerbates the negative effects of the ERI 2, . In Japan, the economic recession of the 1990s and increased international competition have forced companies to restructure. The Japanese traditional systems, which include lifetime employment and seniority-constrained wages and promotions, are being dismantled. Consequently a performance-based pay system has been introduced that has resulted in a competitive working climate, over-commitment, and job insecurity among workers. Fatigue may lead to occupational accidents in the workplace, as well as negative health outcomes. In this study, Siegrist’s hypothesized model, the negative effect of ERI on fatigue and its exacerbation through over-commitment, was assessed in Japanese overtime workers 2, .

Blood lead and erythrocyte protoporphyrin levels in association with smoking and personal hygienic behaviour among lead exposed workers

Aims: To investigate the effects of smoking and personal hygienic behaviour on blood lead (BPb) and free erythrocyte protoporphyrin levels (FEP) in lead exposed workers. Methods: Subjects were 105 lead exposed male workers in a battery recycling plant during the years 2000–03. BPb and FEP were measured as part of the ongoing occupational surveillance. Each worker completed a questionnaire for assessment of smoking and four measures of personal hygienic behaviour (glove and mask use, hand and face washing before meals during working hours). Results: Statistically significant decreases in mean BPb and FEP occurred during the three years. The proportion of BPb reduction in the non-smoking workers was significantly higher (mean 24.3%) than in the smoking workers (15.3%). When the workers were classified into three groups (excellent, good, and poor) based on the four personal hygienic behavioural indicators, the greatest decreases of BPb and FEP were observed in the non-smoking workers of the excellent group. Conclusions: The consistent use of protection devices and cleanliness at work appeared to contribute to the lowering of BPb and FEP. Cessation of smoking in the workplace was also of importance.

Effect of Overtime Work and Insufficient Sleep on Postural Sway in Information-Technology Workers

In Japan, death from overwork (“karoshi” in Japanese) is the focus of social concern. Extremely long work hours and deprivation of sleep exert vital exhaustion and mood changes, resulting in disease conditions such as depression and ischemic heart disease . As the prevention of diseases caused by heavy overtime schedules is a live issue in Japan, decisive and objective indicators are necessary for the early detection of irrecoverable damage to workers’ health. Young overtime workers, under forty, are often passed over by routine medical check-ups, nevertheless they have been suffering from shortened sleep and lack of effective rest. Especially information-technology workers in Japan are involved in extreme overwork beyond daytime working hours in order to compete in the global market. Detailed health assessments should be carried out with a view to identifying and implementing measures to relieve adverse health effects in overtime workers. The critical flicker fusion frequency (CFF) test is a suitable method for the measurement of short-term visual strain , however, few studies have indicated that CFF is sensitive as an objective measure of chronic fatigue. Therefore other convenient tools are required to detect exhausted workers at risk. Computerized static posturography has been used to examine balance function disorders, measuring displacements of the body’s center of pressure by the use of a force platform during static upright posture. The posturographic measurements are reportedly suitable for monitoring fatigue. Since continued insufficient sleep can lead to inability to concentrate, perceptual changes and dizziness, we performed a quantitative study using postural sway parameters as the disturbance stimulation of foot pressure movement in order to evaluate fatigued conditions of overtime workers at the early stage. The purpose of this study was to find medical evidence for the effects of extended working hours and short sleep time among younger workers under forty, and to recommend certain measures for their health assessment and control.