This review deals with three aspects of occupational health practices in Japan, i.e., working environment control, work practice management and health care, with an emphasis upon working environment control. Control of chemical hazards and physical agents in working environment is of prime importance to prevent workers from health impairments due to the hazardous agents. The Japanese legislative system for control of hazardous agents in working environment is characterized by “workplace control”, and it is different from“control of personal exposure based on exposure limits of hazardous substances”. Hazardousness of working environment contaminated with a toxic substance is assessed by screening air sampling at workplace designated as Measurement A and by fixed point air sampling designated as Measurement B. Working environment was categorized as Control Class I, II or III with both geometric mean and geometric standard deviation of concentrations of the hazardous agent with reference to an“administrative control level”. The nationwide survey of air concentrations of dust and lead at workplaces revealed that the present Japanese system of working environment control had been effective to reduce the number of the harmful workplaces evaluated as Control Class III, the worst category, in the decade of 1984-1993 throughout Japan.
To ensure the effective performance of active carbon tubes for working environment measurements, suitable desorbing solvents were selected for 46 kinds of organic compounds by the phase equilibrium method. The criteria for suitable desorbing solvents in this study was desorption of the objective compounds from active carbon at efficiencies greater than 90% and to give good separation between its own peak and that of the objective compound on a gas chromatogram. For most non-polar or hydrophobic compounds, carbon disulfide was a versatile and effective solvent. But for polar and hydrophilic compounds like alcohol, N, N-dimethylformamide and dimethylsulfoxide were good desorbing solvents if their peaks did not overlap with those of the objective compounds. Mixtures of lower molecular weight alcohols with carbon disulfide or dichloromethane could be alternative solvents for hydrophilic compounds as well. A thermodynamic parameter of the solute-solvent system, i.e., the mixing energy derived from the solubility parameter, gave a rough indication of the effectiveness of solvents but it could not be used as a critical indicator for the efficient desorbing solvents for organic vapors collected on active carbon.
A simple analytical method was developed to determine p-nitrochlorobenzene (p-NCB) in working environmental air by reversed-phase high-performance liquid chromatography (HPLC). Nitrobenzene, nitrotoluene isomers, and NCB isomers were separated and p-NCB was determined by reversed-phase HPLC as follows: column; Hitachi gel #3056 (4.0mm I.D. x 150mm), mobile phase; 2-propanol: water (40:60, v/ v) with a flow rate of 0.8ml/min, column temperature; 50°C, detector; UV detector at 270nm. Nitrobenzene, o-, p-nitrotoluene, and o-, m-NCB were separated from p-NCB, but m-nitrotoluene could not be completely separated from p-NCB. The limit of detection (signal-to-noise ratio of 3:1) of p-NCB was 0.3ng. Repeatability of the HPLC method was excellent. The HPLC method enabled to determine one-tenth of the administrative level (1mg/m3) of p-NCB, since the lower limit of determination was 0.05mg/m3. Therefore, the present HPLC method proved to be applicable to the determination of p-NCB in working environmental air.
A total sample preparation method utilizing one membrane filter for all or some of the measurements by phase contrast optical microscopy (PCM), optical microscopy (OM), dispersion staining polarized microscopy (DS/PLM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), was developed in order to evaluate airborne asbestos and other mineral fibers comprehensively, including fiber number, sizes and types, in various environments. This method consists of two alternate procedures: parallel and serial preparation. The former uses different portions of a filter for each measurement of PCM, OM, DS/PLM, SEM and TEM. The latter uses a single filter portion for all OM, SEM and TEM measurements by which the same area and same fibers on the filter can be observed. This allows fiber numbers to be directly compared using these measurements on the same filter area, and the fibers observed by OM can be also examined by SEM and/or TEM equipped with an energy dispersive X-ray spectrometer (EDX) to determine the types and precise sizes. Using this method, it was found that OM measurements developed in this study can visualize thinner fibers than PCM measurements and make it easier to count fibers. We also found that currently used PCM measurement can detect fibers thicker than about 0.4-0.5μm in diameter. This total sample preparation method can be used not only for air samples, but also for liquid and biological tissue samples.
The concentrations of indoor pollutants generated from types of heaters were measured in a model room of 20m2 in area and 45m3 in capacity. We used six different heaters: three kerosene heaters of different types, town and propane gas heaters, and an electric heater. Three ventilation conditions were introduced into each experiment: non-ventilation, fan-on ventilation with closed door and fan-off ventilation with half-opened door. The results obtained by heating under non-ventilation condition were as follows: The concentrations of NO2 and CO2 were comparatively high and the values obtained from all the heaters except the electric heater exceeded the 1-hr Environmental Quality Standards, Japan (EQS NO2: 0.04-0.06ppm) and the Building Sanitation Management Standards, Japan (BSMS CO2: 1, 000ppm), respectively. The CO concentration emitted from reflection kerosene and town gas heaters slightly exceeded the BSMS (10ppm). The concentrations of suspended particulate matter and polynuclear aromatic hydrocarbons showed an increasing tendency during the use of kerosene-fueled heaters. Under two ventilating conditions, NOx concentration decreased to less than a third in comparison with non-ventilating condition.
In the standard of the approval test for dust respirator certification, test aerosols are defined as air containing quartz particles of 2μm or smaller1). However, it is well-known that the filtration efficiency of air filters depends on the size of the test aerosol particles. Alternative test aerosols containing submicron size particles will be studied for use in future approval test of dust respirators. Before searching for alternatives, characterization of currently-used quartz dust, e.g. information about size and electrostatic charge of the aerosol particles, should be determined. The currently-used approval test measures filtration efficiencies with a light scattering photometer. The photometer gives overall aerosol concentration, while Aerodynamic Particle Sizer (APS-33B, TSI Inc., St. Paul, U.S.A.) is able to give the number concentration for each particle size based on the aerodynamic diameter ranging from 0.9 to 2.0μm. In this study, equivalent diameter was defined as the diameter at which penetration has the same value when measured by APS-33B and by light scattering photometer. The equivalent diameter for the ten filter samples for dust respirator was around 1μm, irrespective of neutralization of the test aerosol.
Breakthrough times of a commercially-available respirator cartridge packed with a small amount of activated carbon were determined by three different flow patterns: workers' respiratory patterns, conventional steady-state flows, and three standard patterns consisting of rectangle, sine, and triangle waves. A mechanical breathing simulator was used to reproduce the three standard wave patterns as well as the workers' respiratory patterns, which had been recorded from three workers of a paint manufacturing plant wearing a gas mask equipped with a respirator cartridge. The breakthrough test was carried out with 300ppm carbon tetrachloride vapor at average flow rates of the respiratory and standard patterns equivalent to the steady-state flow rates. The breakthrough times determined by the workers' respiratory patterns were found to be shorter than those by a steady-state flow of the equivalent flow rate, and to be as short as those by sine and triangle wave patterns. It was considered that shorter breakthrough times in the workers' respiratory patterns could be attributed to a faster maximum inspiratory flow rate than that in the case of steady-state flow. The present results suggest that the passing time of CCl4 molecules through the thin activated carbon layer of respirator cartridge may be too short to attain an adsorption equilibrium.
This study evaluated the effect of designated smoking areas in an office and the efficacy of air cleaners in a smoking room. The concentrations of suspended particulates (SP) were measured at 13 points in the office, including the smoking room, corridors around the smoking room, and a non-smoking office. The SP concentrations were between 0.52 to 1.31mg/m3 in the smoking room, 0.06 to 0.22mg/m3 in the corridors and 0.03 to 0.05mg/m3 in the non-smoking office, respectively. The results showed that the area restriction on smoking in this office was successful, although an outflow of tobacco smoke was observed in the corridors. The SP concentration in the smoking room where three electrostatic air cleaners had been installed was monitored over 24 hours. The SP concentration due to tobacco smoke in the smoking room was much greater than the control concentration for SP in air-conditioned buildings in Japan, that is, not more than 0.15mg/m3. The effectiveness of electrostatic air cleaners in closed smoking rooms is discussed.
In order to design proper ductwork for a local exhaust system, airflow characteristics were investigated in straight pipes of unplasticized polyvinyl chloride (PVC). A linear decrease in static pressure was observed downstream at points from the opening of the VU pipes (JIS K 6741) located at distances greater than 10 times the pipe diameter, for velocities ranging between 10.18-36.91m/s. Roughness inside pipes with small diameters was found to be 0.0042-0.0056mm and the friction factor was calculated on the basis of Colebrook's equation for an airflow transition zone. An extended friction chart was then constructed on the basis of the roughness value and the friction factor. This chart can be applied when designing a local exhaust system with the ducts of diameters ranging from 40 to 900mm. The friction loss of the PVC pipe was found to be approximately 2/3 of that of a galvanized steel pipe.
The purpose of this paper is to clarify the temporary threshold shifts in fingertip vibratory sensation produced by hand-transmitted vibrations that have the same equivalent tool vibration levels according to the JIS B 4900 determination method. The JIS B 4900 standard is based on vibration exposure dose values. Therefore, even though the vibration exposure pattern is varied, the severity of vibration at the end of vibration exposure has a same value if the equivalent tool vibration level is unchanged. The experiment was conducted by using four kinds of hand-transmitted vibration patterns as stimuli. As a result, although the vibration transmitted to the hand by steady continuous vibration, intermittent vibration with short pauses, intermittent vibration with long pauses and repeated single bursts of vibration all have the same equivalent tool vibration levels (equal vibration exposure dose value) according to the JIS B 4900 determination method, the TTS after vibration exposure did not produce the same value. Therefore, these results suggest that the determination methods of the JIS B 4900 standard are not adequate for describing the vibration exposure dose value.
The present study was carried out for screening some biochemical changes due to occupational exposure to contraceptive drugs. It included 18 male workers and 22 female workers involved in the manufacture of contraceptive pills and 34 female workers manufacturing contraceptive ampoules. The levels of some sex hormones and gonadotropins were evaluated. Some parameters of blood picture, blood coagulation, liver and kidney functions, lipid profile and trace elements metabolism were assessed. Results were compared with those of a control group composed of 19 males and 27 females. Increased levels of estrogen among exposed workers was the main finding. It has been attributed to liver rather than pituitary dysfunction. A less atherogenic lipid profile has also been found. Referral to preventive measures has been recommended.
To investigate physiological and psychological effects of industrial noise, a survey was performed on 50 female workers exposed to machinery noise [93-100 dB(A)] (noise group) and 25 female workers in less-noisy environments [71-75 dB(A)] (control group) in a textile factory in Vietnam. Urine was collected for analysis of catecholamines and cortisol. The subjects were also asked to fill out a questionnaire. Each subject was examined over 2 working days. The workers in the noise group were asked to put earplugs in their ears during the working hours of the 2nd day. On the 1st day without earplugs, urinary excretion of catecholamines in the noise group were greater than those in the control group. Cortisol in urine showed a similar tendency. Differences in catecholamine excretion between the noise group and the control group decreased on the 2nd day when the earplugs were used for attenuation of noise level in the noise group. Frequency of subjective fatigue symptoms was lower on the 2nd day than that on the 1st day in the noise group, while the control group showed almost no day-difference. The results indicate that the catecholamine response to noise in workers was reduced through the use of earplugs.
The present study was designed to examine the effects of a single cognitively demanding task on the R-R interval and systolic blood pressure (BP) power spectra. Ten healthy volunteers were asked to perform an English transcription task for 90 minutes using a word processor, and to read books as a non-task control. The influences of both posture and respiration were controlled in assessing the task effects. Performance of the single cognitive task significantly increased the normalized low-frequency component (%LF) of the BP spectrum following the task, as compared to the non-task control in the sitting position. However, the supine position did not produce the post-task increase in % LF of the BP spectrum. The spectral components of the R-R interval spectrum remained unchanged after the task. These results suggest that the post-task increase in sympathetic activity may be reflected by the BP spectrum under sympathetic predominance in the sitting position.