The purpose of the present study was to compare the physiological responses to different types of mental stress encountered in the workplace. Circulatory and central nervous system responses were examined in 8 healthy males by exposing them to 20-min of white noise (80 dB(A)) and 20-min of computer-based mental arithmetic tasks as models of vascular and cardiac stress, respectively. The results indicated that both cardiac and vascular stresses increased blood pressure and showed a cumulative effect as exposure period was extended. Heart rate and prefrontal oxygenated hemoglobin levels (measured by NIRS) increased in the face of cardiac stress but were not clearly altered by vascular stress and indicated that cardiac stress higher cardiac response and requires more oxygen supply to the brain. As the central nervous system responded, an event-related potential P300 component was elicited by an auditory oddball task presented before and after each stress. The P300 amplitude increased for both stresses. However, P300 latency increased in response to cardiac stress but decreased with vascular stress in the left prefrontal. Thus, the circulatory and central nervous system responses to cardiac stress and to vascular stress may have different underlying mechanisms, and measuring physiological indices appears to be an effective method by which to evaluate the influence of mental stress.
The assessment of the occupational electromagnetic field exposure of welders is of great importance, especially in shielded-arc welding, which uses relatively high electric currents of up to several hundred amperes. In the present study, we measured the magnetic field exposure level of welders in the course of working. A 3-axis Hall magnetometer was attached to a subject’s wrist in order to place the sensor probe at the closest position to the magnetic source (a cable from the current source). Data was acquired every 5 s from the beginning of the work time. The maximum exposed field was 0.35-3.35 mT (Mean ± SD: 1.55 ± 0.93 mT, N=17) and the average value per day was 0.04-0.12 mT (Mean ± SD: 0.07 ± 0.02 mT, N=17). We also conducted a finite element method-based analysis of human hand tissue for the electromagnetic field dosimetry. In addition, the magnetic field associated with grinders, an air hammer, and a drill using electromagnetic anchorage were measured; however, the magnetic fields were much lower than those generated in the welding process. These results agreed well with the results of the electromagnetic field dosimetry (1.49 mT at the wrist position), and the calculated eddy current (4.28 mA/m2) was much lower than the well-known guideline thresholds for electrical nerve or muscular stimulation.
A number of reports have been published regarding the applicability of existing regulatory frameworks to protect consumers and the environment from potentially adverse effects related to introduction of nanomaterials into commerce in the United States and the European Union. However, a detailed comparison of the regulatory approaches to worker safety and health in the USA and in the EU is lacking. This report aims to fill this gap by reviewing regulatory frameworks designed to protect workers and their possible application to nanotechnology.
In our previous study, we elicited effectual points of view (POV) in occupational health management for visual display terminals (VDT) operators with disabilities. In order to validate the POV, two VDT operators with cerebral palsy newly-participated in our case study. Problems were ascertained, and in order to attempt to reduce the workload and improve operability, we performed intervention using ergonomic measures. Evaluations were conducted through observations of the equipment used and posture, as well as measurements of sitting pressure distribution and surface electromyogram. For Case 1 (a 33 yr-old male), a trunk support was introduced inside the armrest of his chair to maintain the trunk in a comfortable position. For Case 2 (a 21 yr-old female), in order to improve her unstable sitting position, we changed her chair and adjusted it to an appropriate desk height. For both cases, we confirmed improvements in posture, sitting pressure distribution, myoelectric potential or operability. We were able to confirm that “maintaining of a comfortable trunk” and “alleviation of excessive bending, extension, and curvature of the spinal column and joints” obtained from the previous study as POV in health management are also effective in the present interventional cases.
The aim of this study is to develop a practicable worksite physical fitness program for small and medium-sized enterprises (SMEs). Community-based intervention consisting of a three-month exercise course was conducted, and its benefits evaluated. A self-administrated structured questionnaire and physical fitness examination were designed to compare the difference between pre and post intervention. A total of 133 SME workers completed the lifestyle/exercise course and filled out the questionnaire, but 16 were excluded from the exercise group due to health reasons. After the intervention, health indicators such as weight, blood pressure, resting heart rate, waistline, BMI, front and back trunk flexibility, abdominal muscle durability and back muscle strength were significantly improved, and improvements in musculoskeletal disorders were seen in reduced neck pain (18.8%), wrist pain (17.4%), and upper/lower back pain (8.7% and 21.7%, respectively). Cardiovascular risk factors (BMI and resting heart rate) showed a significant improvement related to frequent participation in the program (p=0.02), and the exercise group reported a significant difference in overall health (p=0.02). This study has demonstrated an effective approach to community-based fitness intervention through SMEs.
Our previous study suggested that the work form is related to the maximum oxygen uptake (VO2max). Therefore, we test the hypothesis by a longitudinal study that, besides these lifestyle-related factors, the work form increases VO2max among workers. Seven hundred and ninety nine males aged 37.1 ± 10.6 and 395 females aged 37.7 ± 10.5 (range: 20 to 59 yr old), who participated in The Total Health Promotion Plan (THP) at their respective workplaces twice in one year from 1997 to 1998, were selected. Data on VO2max were analyzed for age, systolic blood pressure (SBP), body mass index (BMI), work form (sedentary, standing, and ambulatory), exercise, and smoking. Age and the baseline variables for BMI and for VO2max showed significant negative relationships with a change in VO2max in males and females. Further, a change in the BMI showed a significant negative relationship with a change of VO2max in males. However, exercise habit and an ambulatory work form showed significant positive relationships with a change of VO2max in males. It was suggested that after adjusting for other factors in males, an ambulatory work form may be associated with an increase in VO2max in one year.
Glutaraldehyde (GA) and ortho-phtalaldehyde (OPA) have been widely used as major components of disinfectants in hospitals. We evaluated the alterations in GA or OPA in rats after subacute inhalation exposure by determining levels of neurotransmitters (norepinephrine [NE], dopamine [DA], DA metabolites, dihydroxyphenylacetic acid [DOPAC] and homovanillic acid [HVA], indoleamine serotonin [5-HT] and 5-HT metabolite, 5-hydroxyindoleacetic acid [5-HIAA]) in discrete brain regions using high performance liquid chromatography (HPLC) equipped with an electrochemical detector. Female Wistar rats were exposed to 0, 50, 100, or 200 ppb gaseous GA or OPA by inhalation for 1 h per day, 5 d per week for 4 wk. Following the exposure, the brain of each rat was removed and dissected into cerebrum, cerebellum, medulla oblongata, midbrain, corpus striatum and hypothalamus. The neurotransmitters and their metabolites were extracted from each brain region, and determined by HPLC. Regarding GA, the daily water intake of the 50 or the 200 ppb exposed groups was significantly lower than that of the control. DA and 5-HIAA levels in the medulla oblongata among the GA exposed groups were significantly lower than those of the control. For OPA, the mean final body weight and daily food intake of the 100 or 200 ppb exposed groups were significantly lower than those of the control. The mean DA concentrations in the cerebrum in the groups exposed to OPA were significantly lower than those of the control. OPA may modulate DA metabolism in the cerebrum of female rats. The levels GA or OPA that induced alienations in neurotransmitters were comparable to those levels usually found in hospitals, further studies are warranted to evaluate the of safety of disinfectants containing GA or OPA.
Cadmium in blood (Cd-B) is an important indicator, next to Cd in urine, in biological monitoring of exposure to Cd. The present study was initiated to examine compatibility in results of analysis for Cd-B between graphite furnace atomic absorption spectrophotometry (GFAAS) and inductively-coupled plasma mass-spectrometry (ICP-MS). For this purpose, 1,159 blood samples were collected from adult women (with no occupational exposure to Cd) in eight prefectures nation-widely in Japan. The samples were analyzed by the two methods; geometric mean (the maximum) concentrations were 1.22 (6.90) μg/l by ICP-MS, and 1.47 (7.40) μg/l by GFAAS. Statistical analyses showed that there was a close correlation between the results by the two methods. The regression line (with ICP-MS and GFAAS results as an independent variable and a dependent variable, respectively) had a slope close to one and an intercept next to zero to suggest that ICP-MS gave values compatible with that of GFAAS. Further analysis with the ratio of Cd-B by GFAAS over that by ICP-MS revealed that the two results were close to each other, and that the agreement was even closer when Cd-B was >2 μg/l. Thus, the two methods can be employed inter-convertibly when Cd-B is relatively high, e.g. >2 μg/l. Care may need to be practiced, however, for possible ‘between methods’ difference when Cd-B is low, e.g., ≤2 μg/l.
In order to investigate whether or not dispersed nanoparticles have an effect of inflammation and fibrosis on animals, we developed a nanoparticle generation system and examined the gene expression of matrix metalloproteinase (MMP) and tissue inhibitor matrix proteinase (TIMP) in rat lung containing inhaled nickel oxide (NiO) or titanium dioxide (TiO2) nanoparticles. In both experiments, Wistar male rats were exposed to NiO or TiO2 nanoparticles for 4 wk (6 h/day). The geometric mean diameters of NiO and TiO2 in the chamber were 139 ± 12 nm and 51 ± 9 nm, respectively. The average concentration of the particle number of NiO and TiO2 was 1.0E+05 /cm3 and 2.8E+05 /cm3, respectively. At 4 d, 1 and 3 months after the end of the inhalation, the rats exposed to these particles were sacrificed and the gene expressions of MMP-2, TIMP-2 and type I collagen were measured using RT-PCR. Pathological finding revealed that there was minimum inflammation with nickel oxide only at 4 d and no change with titanium oxide. However, there were no changes of the gene expression of MMP-2, TIMP-2, and type I collagen in either the NiO or TiO2 exposure groups. In this study, inhalation of nickel oxide and titanium dioxide nanoparticles did not induce the gene expression of MMP-2 and TIMP-2 mRNA in rat lungs.
The study objective was to investigate the impact of different kinds of organizational changes, as well as anticipation of such changes, on work-related stress, sleep, recovery and health. It was hypothesized that impaired sleep and recovery increase the adverse health consequences of organizational changes. The data consisted of cross sectional questionnaire data from a random sample of 1,523 employees in the Swedish police force. It could be shown that extensive organizational changes including downsizing or a change in job tasks were associated with a small increase in work stress, disturbed sleep, incomplete recovery and health complaints. However, less extensive organizational changes like relocation did not affect these outcome variables. Anticipation of extensive organizational changes had almost the same effect as actual changes. Furthermore a moderating effect of sleep and work stress on gastrointestinal complaints and depressive symptoms was found. Thus, like former studies already suggested, extensive organizational changes resulted in increased stress levels, poorer health and impaired sleep and recovery. Furthermore, organizational instability due to anticipation of changes was as negative as actual changes. There was also some evidence that disturbed sleep increased these adverse health effects, in particular with respect to anticipation of organizational changes.
We investigated the predictors significantly associated with a lifestyle to prevent or combat the metabolic syndrome among Japanese workers. We conducted an anonymous self-administered questionnaire survey and analyzed the resulting data using multiple linear regression analysis. The dependent variable was a lifestyle to prevent or combat the metabolic syndrome (7-point scale). Independent variables were: subjects’ basic attributes (age, gender, blue or white collar worker, with or without a family physician), Multidimensional Health Locus of Control (7-point scale for each item), with or without the metabolic syndrome being pointed out or not by healthcare providers, and 4 items regarding the metabolic syndrome produced with reference to the Health Belief Model (7-point scale for each item). Those independent variables were all included in this model. The analysis shows the older workers, white-collar workers, and workers who had the metabolic syndrome pointed out by healthcare providers had appropriate lifestyles. Those with high scores in Powerful Others Health Locus of Control also had appropriate lifestyles. Those who realized that the metabolic syndrome was a life-threatening disease and who knew practical ways to prevent or combat the metabolic syndrome also had appropriate lifestyles. Our findings can be applied to various types of medical education regarding the metabolic syndrome.
Occupational exposure to asbestos fiber of brake repair job (auto mechanics) has seldom been evaluated in Iran. Accordingly, we evaluated asbestos fiber concentrations in the breathing zone of auto mechanics between July 2008 and December 2008. The asbestos fiber concentrations of 60 personal air samples collected from 30 cars and trucks brake replacement and they were analyzed by phase-contrast optical microscopy (PCM) and scanning electron microscopy (SEM) by energy-dispersive X-ray analysis. The geometric means of the personal monitoring fiber concentrations were 0.92 PCM f/ml and 0.46 PCM f/ml respectively in car and passenger heavy truck auto shops. There was a significant differences in the asbestos fiber concentrations between the car and truck auto shops (p=0.006). Based on these findings, auto mechanics who worked with asbestos containing brake may have been exposed to asbestos concentrations approximately 7 times higher than the current occupational safety and health agency (OSHA) permissible exposure limit (PEL) of 0.1 f/ml. Fiber morphology and energy dispersive X-ray analysis by SEM revealed that amphibole fibers such as tremolite and actinolite existed in the brakes dust and that the vast majority (>30%) of the airborne chrysotile fibers were greater than 1 μm in diameter. It can be concluded that the imported chrysotile asbestos contains trace amounts of tremolite and actinolite fibers and they are responsible for the high airborne asbestos levels and occupational exposure to amphibole asbestos in auto mechanics job in Iran. Thus, it is to be expected that the auto mechanics will suffer negative health effects due to exposure to the serpentine and amphibole asbestos fibers.
The purpose of this study was to examine the correlation of medical incidents and errors among nurses with factors describing their lifestyle, health, and work environment. We analyzed questionnaires completed by 6,445 female hospital nurses engaged in shift work in Japanese hospitals with general wards of more than 200 beds. Logistic regression analysis indicated that the risk for medical incidents/errors was predicted by being under treatment, absence due to sickness in the past 6 months, workplace, break times during night shift, bodily pain, and role (emotional). These results indicate that to prevent the occurrence of medical incidents/errors, it is necessary to regard current/recent illness, bodily pain, and role (emotional) as a nurse’s personal problems and break times during the night shift and workplace as administrative problems.
Given the well-known difficulties in defining and detecting fatigue, it is a real challenge to incorporate it into either traffic or criminal law. Finnish traffic law forbids fatigued driving “only” on a general level concerning the driver’s fitness to drive. We present several comments from Finnish traffic and local police officers regarding their own experiences of driving while fatigued. The comments were extracted from a larger survey of traffic (N=129) and local (N=100) police officers, and prosecutors (N=96). Although the main topic of the survey was the application of the law that forbids fatigued driving, some police officers raised the issue of their own behavior in this respect. We argue that many shift workers, including police officers, break the law, especially when driving home after a night shift.
Charcoal, often used as cooking fuel at some restaurants, generates a significant amount of carbon monoxide (CO) during its combustion. Every year in Japan, a number of cooks and waiters/waitresses are poisoned by CO emanating from burning charcoal. Although certain ventilation is necessary to prevent the accumulation of CO, it is difficult to estimate the proper ventilation requirement for CO because the generation rate of CO from burning charcoal has not been established. In this study, several charcoals were evaluated in terms of CO generation rate. Sample charcoals were burned in a cooking stove to generate exhaust gas. For each sample, four independent variables — the mass of the sample, the flow rate of the exhaust gas, CO concentration in the exhaust gas and the combustion time of the sample — were measured, and the CO generation rate was calculated. The generation rate of CO from the charcoal was shown to be 137-185 ml/min/kW. Theoretical ventilation requirements for charcoals to prevent CO poisoning are estimated to be 41.2-55.6 m3/h/kW.
To clarify the genotoxicity of ethyl tertiary butyl ether (ETBE), a gasoline additive, male and female C57BL/6 mice of Aldh2+/+ and Aldh2–/– genotypes, aged 8 wk, were exposed to 0, 500, 1,750, or 5,000 ppm ETBE for 6 h/day, 5 d per week for 13 wk. DNA damage in leukocytes was measured by the alkaline comet assay and expressed quantitatively as Tail Intensity (TI). For male mice, TI was significantly higher in all three groups exposed to ETBE than in those without exposure within Aldh2–/– mice, whereas within Aldh2+/+ mice, TI increased only in those exposed to 5,000 ppm of ETBE as compared with mice without exposure. For female mice, a significant increase in TI values was observed in the group exposed to 5,000 ppm of ETBE as compared with those without exposure within Aldh2–/– mice; TI in Aldh2–/– mice exposed to 1,750 and 5,000 ppm was significantly higher than in Aldh2+/+ mice without exposure. TI did not significantly increase in any of the groups exposed to ETBE within female Aldh2+/+ mice. Based on the results we suggest that Aldh2–/– mice are more sensitive to DNA damage caused by ETBE than Aldh2+/+ mice and that males seem more susceptible to this effect than females.