In order to investigate the reliability and validity of selected scales from the Japanese version of Job Content uestionnaire (JCQ, Karasek 1985), a survey was conducted of 1, 126 employees of a computer company in Japan using a questionnaire including 31 items from the JCQ. Ten JCQ scales on psychological and physical demands were examined in 603 male and 84 female respondents. Cronbach's alpha reliability coefficients for nine JCQ scales which consisted of two or more items ranged from 0.66 to 0.90 for males and from 0, 64 to 0.88 for females. Item factor analysis for each scale indicated that the first factor explained 50 or more percent of item variation of decision authority, supervisor support, coworker support and Framingham physical exertion in males and females and of psychological demands in females. The skill discretion, decision authority and decision latitude significantly and positively correlated with age, years of employment and years of experience in males (p<0.05). The decision authority significantly and positively correlated with age and years of experience in females (p< 0.05). Psychological demands, Framingham demand and physical exertion significantly and positively correlated with overtime in males and females (p<0.05). Skill discretion, decision authority and decision latitude, psychological demands and Framingham demand were lowest in computer equipment operators; physical exertion and Framingham physical exertion were lowest in computer software engineers/technicians. It is suggested that these JCQ scales are reliable and valid instruments for assessing job stressors in computer company employees in Japan.
This study was conducted to clarify the factors associated with workers' regular physical activity in a Japanese company. The subjects were 515 male employees who responded to a questionnaire given to all male workers (n=761) in a manufacturing company in central Japan. The effective response rate was 67.6%. According to multiple linear regression analysis using the stepwise method as the model-selection method, significant factors associated with workers' regular physical activity were self efficacy, current membership in a sports club, colleague support, perceived barriers to exercise, perceived benefits of exercise, and leisure time. Intervention to increase self efficacy for exercise and to diminish perceived barriers to exercising, together with social support, were thought to be a good potential strategy for increasing the proportion of workers participating in regular physical activity. Intervention programs to increase self efficacy should therefore be developed.
Biochemical hypoglycemia has attracted attention because it triggers accidents through errors in judgment by impairing cognitive function. Its prevalence and associated risk factors have remained unexplored in the area of occupational health. The present study was designed to investigate its epidemiological aspects in male volunteers. The study population of 76 male volunteers, 63 of whom were firefighters and 13 had other jobs, filled out questionnaires by interview covering 37 factors concerning age, physical parameters, past and current health problems, habits (smoking, drinking, and exercise), food preferences and life style. The participants were asked to measure their blood glucose levels 9 times over a representative workday and holiday and record any symptoms of hypoglycemia at the time of measurement. The body fat ratio of each participant was measured by the bioelectrical impedance analysis method. 22.4% of the participants (17/76) experienced biochemical hypoglycemia (less than 60mg/dl) at the time of blood glucose monitoring. Those who experienced biochemical hypoglycemia had significantly lower peak, average and nadir blood glucose levels (p<0.05; 115.1±18.7 mg/dl, 82.2±7.0mg/dl, 52.2±5.6mg/dl, respectively) than those who did not (129.9 ±26.7mg/dl, 97.0±9.9mg/dl, 75.9±9.7mg/dl, respectively). No symptom other than sudden hunger (p<0.05) was correlated with biochemical hypoglycemia. Lower lean body mass index (lean body mass/height2) was the only statistically significant contributory risk factor (p<0.05, Odds ratio: 2.91, 95% confidence interval 1.29-6.65) by multiple logistic analysis. Mean blood glucose levels had a positive correlation with lean body mass index (P<0.0001, r2=0.372). The present results suggest that biochemical hypoglycemia is a potential risk problem in occupational settings. Low L.B.M.I. males should be educated about the possibility of biochemical hypoglycemia whoever have experienced a feeling of sudden hunger. Such precautions should be highly recommended to workers under dangerous and/or tense conditions in order to prevent error accidents in occupational settings.
Hypoglycemia has been reported to occur frequently among individuals with health-related occupations, especially hospital nurses. In this study, we investigated the risk factors of hypoglycemia. Both female hospital nurses and other female workers participated in this study, which included questionnaires, and daily blood glucose monitoring. Responses from 3, 415 workers were included for analysis. 2, 489 workers reported that they had never had hypoglycemic episodes (symptom-free group), while 926 workers reported that they had experienced hypoglycemic symptoms more than once. Of these workers, 207 had had episodes within one year of the study and had experienced them more than once a month (symptomatic group). Thirty-one volunteers were recruited from the above two groups-21 from the latter group and 10 from the former group- and daily blood glucose levels were determined: 6 days for nurses to cover three shifts (dayshift, nightshift and midnightshift) and 2 days for other workers. Nine of 21 volunteers from the symptomatic group had biochemical hypoglycemic reading(s) (<60 mg/dl) during the monitoring; however, none of 10 volunteers from the symptom-free group had such readings. These nine volunteers were found to have lower mean blood glucose levels (p<0.05) and lower minimum blood glucose levels (p<0.05) than other volunteers. Simple logistic analyses revealed multiple risk factors in the symptomatic group. By adjusting the confounding effects, these multiple risk factors were reduced into a small number of risk factors: occupation as a nurse, histories of hypotension and glucosuria, eating snacks, eating deserts, and insomnia. The present report clearly demonstrated that there are hypoglycemic-prone individuals among symptomatic female workers, who were shown to have multiple risk factors for hypoglycemic symptoms.
In this study, the effects of 5-tesla (T) static magnetic fields (SMFs) on food and water intake in BALB/c mice were examined. We also examined body weight changes, organ weights and some serum biochemical parameters to evaluate the physiological changes resulting from changes in food and water intake. Mice were exposed to 5-T SMFs for 24h and 48h. Food intake, water intake and the mean body weight of mice tended to decrease after 24h of exposure to SMFs (p=0.054, p=0.119, p=0.107, respectively). Those parameters decreased significantly after 48h of exposure (p=0.039, p=0.0003, p=0.009, respectively). These results suggested a positive relationship between the duration of exposure, and the responses, represented by food intake, water intake, and body weight of the mice. However, the weights of brain, lungs, heart, liver, spleen, and kidneys did not change after 48h of exposure. The blood urea nitrogen (BUN) levels and blood glucose levels increased significantly after 48h of exposure (p=0.03, p=0.005, respectively). The BUN-to-creatinine (BUN/Cr) ratio tended to increase after 48h of exposure (p=0.07). We conclude that exposure to 5-T SMFs for 48h suppresses eating and drinking behavior. We considered that the decreased body weight, increased BUN levels and slightly increased BUN/Cr ratio after 48h of exposure to 5-T SMFs were due to body fluid loss resulting from decreased food and water intake.
The effect of 50Hz electromagnetic fields on the immune system was assessed by measuring the cytokine production of the peripheral blood mononuclear cells (h-PBMCs) of a healthy individual. The h-PBMCs were exposed in vitro to varying magnetic flux densities of 1, 3, 10, and 30 milliTesla for 3 days. Changes in cytokine production of IL-1β, IL-2, IL-6, IL-10, IFN-γ, and TNF-α were studied using the ELISA method. Significant reduction in TNF-α production by the EMF-exposed h-PBMCs, in comparison with the non-exposed cells, was detected at all exposure levels (p<0.05, p<0.01). Significant increase in IL-1β production and decrease in IFN-γ production were also detected at some exposure strength. No significant differences were detected between the control and the EMF-exposed cells in the production of the other cytokines.
The skin absorption rates of toluene in various solvent mixtures were investigated in mice. The skin absorption rate of toluene in toluene/methanol mixtures exhibited a parabolic relationship to the mixed ratio. The maximum rate was obtained at a mixed ratio of 50% (V/V). The skin absorption rate of toluene at this point (50%) was about 4.7 times higher than that of pure toluene. The permeability coefficient (Kp) of toluene increased as the mixed ratio of methanol increased. Methanol enhanced skin absorption of toluene. The skin absorption rate of toluene in a toluene/benzene mixture was inversely proportional to the concentration of benzene. The Kp of toluene is kept constant through the mixed ratios of benzene, and benzene does not have an enhancing effect on the skin absorption of toluene contained in the toluene/benzene mixture. We examined the effects of various vehicles on the skin absorption rates of toluene in mixtures containing 50% (v/v) of toluene. Methanol was a good penetration enhancer for toluene, and its effect is similar to the effect of well-known skin penetration enhancers like DMSO, N, N-Dimethylacetamide, and N, N-Dimethylformamide. Therefore, it is necessary to take special precautions against the skin absorption of toluene when handing thinners that contain methanol.
Bronchoalveolar lavage (BAL) is a useful and safe method for sampling cellular and biochemical components from the lung. Analysis of bronchoaveolar lavage fluid (BALF) constituents is useful for defining the stage of disease, and for assessing disease progression and the response to therapy in lung disorders. We studied the dynamic changes in various indices for BALF and the accompanying silicotic changes in the lungs of rats at different times after quartz instillation. Total cell counts, LDH activity, protein concentration, and lipoperoxide (LPO) in the BALF of experimental silicotic rats were significantly higher than those of control rats (p<0.05 or 0.01). After instillation, quartz content, total cell counts, LDH activity and protein concentration in BALF tended to decrease over time. These findings suggested that in acute silicosis, quartz can induce serious inflammation and damage the lung, with acute lung proteinosis seen as the main change in this stage.
In the ductwork of local exhaust systems, 90° elbow pipes (JIS K 6739) are commonly used to alter the direction of airflow; thus, are important components of polyvinyl chloride (PVC) ducts. Pressure loss in 90° PVC elbow pipes was investigated by measuring static pressure, and the characteristics of airflow was determined. First, a linear decrease in static pressure was observed at points of the downstream side beyond a distance of 10 times the diameter (10d) from the flanged round opening of the smooth VU ducts (JIS K6741). The linear decrease was also observed at points of the downstream side located at distances of greater than 30d from the elbow pipe. Coefficients of loss in the PVC elbow pipes were found to be constant for the Reynolds numbers ranging from 3.38 x 104 to 5.96 x 105 for all diameters examined, and a chart of pressure loss was constructed with these coefficients. The coefficients of loss in PVC elbow pipes were not equivalent to those of metal stamped elbows for any R/d. However, the differences in the coefficients between the metal stamped elbow and the PVC elbow were smaller with larger R/d values.
LC50 of 2-bromopropane was reexamined by using the OECD guideline in ICR mouse. The mice, 3 males and 3 females, were exposed to 2-bromopropane at five different concentrations for 4h in inhalation chambers. The exposed animals were observed for 14 days. The animals which had survived and died were counted for the LC50 determination. The LC50 was calculated by using a dose-mortality curve at a 95 percent confidence level. The LC50 was 31, 171ppm, and the lowest lethal concentration (LLC) was lower than 29, 528ppm and the lethal concentration at 100% (LC100) was higher than 32, 905ppm.
In order to investigate a role of acetone in urine (AcU, mg/l) as an indicator of occupational exposure to isopropyl alcohol (IPA, ppm), AcU was measured in 80 male workers exposed to this substance in a plastic factory. The exposure concentration of solvent was also monitored personal diffusive sampling in the individuals during morning 4-hr shift. Urine samples were collected near the end of the shift and were analyzed for acetone by head-space gas chromatography. The correlation between airbornre concentration of IPA and its urinary metabolite acetone was significant: AcU (mg/l)=0.031 x IPA (ppm)+0.608, r=0.75, n=80, p<0.001. We established 44ppm as the lowest airborne concentration of IPA that caused excessive urinary excretion of acetone which could be discriminated from the endogenous production of acetone in non-exposed people. This concentration was as low as one ninth to one tenth of the current exposure limit of 400ppm. At higher concentrations than 44ppm, AcU was found to be a useful index for monitoring occupational exposure to IPA.
Chlorinated phenols are widely used in the manufacture of biocides and wood preservatives. 2, 4-dichlorophenol administered perorally 3 times a week at a dose of 40 mg in 0.2ml of olive oil per kg of body weight to guinea pigs increased lipid peroxidation in liver and adrenals after 2 weeks of treatment. A high intake of ascorbic acid (50mg/animal/day) significantly decreased lipid peroxidation in the liver of 2, 4-dichlorophenol treated guinea pigs in comparison to guinea pigs with low ascorbic acid intake (2mg/animal/day). 2, 4-dichlorophenol accumulation was also decreased in the liver of animals with high ascorbic acid intake. Increased daily intake of vitamin C to persons involved in production and use of chlorophenoxy herbicides is recommended.
Study was conducted in a group of 32 persons engaged in liquid phase epitaxial growth of mercury cadmium telluride (MCT) layers for nearly 11 years. Airborne mercury concentrations in work environment have been exceeding the threshold limit value of 0.05mg/m3 recommended by ACGIH1). Hg concentration in workplace during peak working hours remained between 0.04-0.08mg/m3. Findings were compared with 32 unexposed referents. Mercury value was estimated 1.60±0.20 (mean±SD) in control, and in Phase I and II, 10.72±1.34ng Hg/ml and 8.08±1.15ng Hg/ml of blood respectively. Results indicate a fall in blood mercury level during the second phase of study. But the values did not return to normal even after a gap of 3 months. An individual who met with a mercury accident showed 226ng Hg/ml of blood which decreased to 25ng/ml after 3 months. It is inferred from the present study that Hg level has increased significantly in MCT workers during working period, and also in non-working period, the values were higher than controls.
Noise study has been undertaken in the three units of a polyester fiber plant. The level and frequency characteristics of the prevailing noise have been studied and speech interference levels evaluated. The results are discussed with reference to the maximum permissible occupational noise exposure limits as allowed by the ISO and other national standards. Some recommendations have also been made to provide safety measures to the workers against high level noise in these units.