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We investigated the adsorbed amount of organic solvent vapors and adsorption rate of a new porous carbon material made from rice husk (rice husk activated carbon) in comparison with those of coconut shell activated carbon by the breakthrough curve. The adsorbed amount on the rice husk activated carbon and that on the coconut shell activated carbon were 81.3 ± 3.3 mg/g and 71.7 ± 5.0 mg/g for acetone, 8.0 ± 1.7 mg/g and 6.3 ± 0.2 mg/g for methanol, 196.8 ± 8.8 mg/g and 262.8 ± 10.4 mg/g for ethyl acetate, 234.8 ± 11.9 mg/g, and 364.6 ± 43.8 mg/g for toluene, respectively. These results suggest that the amount of organic solvent vapors adsorbed per unit weight of rice husk activated carbon is slightly larger for high polar compounds and is smaller for low polar compounds than that of coconut shell activated carbon. We compared the adsorption rate of the two materials by using the slope of the breakthrough curves. Even though there are some limitations to the characteristics of the new porous carbon material, it may be possible to use rice husk activated carbon as an alternative to coconut shell activated carbon in occupational and environmental measures.

Previously, we reported that prenatal exposure to 1-bromopropane (1-BP) causes the accumulation of bromide (Br-) in the brain of rat pups. Here, we aimed to investigate the effects of Br- accumulation in rat pups prenatally exposed to 1-BP vapor. Dam rats were exposed to 1-BP (400 or 700 ppm; 1-BP group) by inhalation, or to NaBr (20 mM; Br- group) in drinking water during gestation days 1-20. We also analyzed pentylenetetrazole (PTZ, 60 mg/kg, ip)-induced behavioral changes in pups prenatally exposed to 1-BP or Br- on postnatal day (PND) 14. PTZ-induced epileptic convulsions were inhibited in both 1-BP (700 ppm) and Br- groups. The inhibition of neuronal excitability induced by Br- was evaluated electrophysiologically using the hippocampal slices obtained from PND14-16 pups. PTZ (2 mM) failed to induce epileptiform discharge in the presence of 1.2 mM Br- in the slices obtained from the control group. However, it induced epileptiform discharge following the removal of Br-, by perfusing artificial cerebrospinal fluid into the slices obtained from the Br- group. Our results indicate that Br- accumulates in the brain of neonatal rat pups prenatally exposed to 1-BP vapor suppressed neuronal excitability.

Objectives The present study aimed to develop a method for measuring the ceiling level of ortho‐phthalaldehyde (OPA) exposure and evaluate the ceiling levels of OPA exposure among health care workers who handle disinfectant solutions containing OPA for the disinfection of endoscopes. Methods The study consisted of a preliminary survey and main survey. In the preliminary survey, processes involving high‐concentration exposure to OPA were identified by video‐exposure monitoring (VEM). In the main survey, the ceiling levels of OPA exposure for high‐concentration exposure processes identified from the results of the preliminary survey were determined using a measuring method combining sampling using a 2,4‐dinitrophenylhydrazine‐silica cartridge and analysis by high‐performance liquid chromatography tandem mass spectrometry. Results In the preliminary survey, seven processes involving high‐concentration exposure to OPA were identified by VEM. The duration of each process was short, lasting from 20 seconds to a few minutes. In the main survey, the OPA concentrations for the identified high‐concentration exposure processes ranged from 1.18 to 4.49 ppb, which markedly exceeded the threshold limit value ceiling (TLV‐C) of 0.1 ppb recommended by the American Conference of Governmental Industrial Hygienists. Conclusions The method for measuring the ceiling level of OPA exposure was established using VEM and the highly sensitive method of chemical analysis; and we successfully evaluated the ceiling levels of OPA exposure among health care workers engaged in endoscope disinfection. This approach can also be applied to other chemical substances with recommended TLV‐Cs, and important information for reducing exposure can thus be obtained.

Objectives Although 1‐Bromopropane (1‐BP) exposure has been reported to cause neurotoxicity in adult humans and animals, its effects on the development of the central nervous system remain unclear. Recently, we reported delayed developmental neurotoxicity (DNT) upon 1‐BP exposure in rats. Here we aimed to study the effect of prenatal 1‐BP exposure on the hippocampal excitability in the juvenile offspring. Methods Pregnant Wistar rats were exposed to vaporized 1‐BP for 20 days (6 h/d) with concentrations of 0 (control), 400, or 700 ppm. Hippocampal slices were prepared from male offspring during postnatal days (PNDs) 13, 14, and 15. Field excitatory postsynaptic potential (fEPSP) and population spike (PS) were recorded simultaneously from the CA1 region. Results In the exposed groups, the stimulation/response relationships of fEPSP slope and PS amplitude were enhanced more than in the control group at PND 14. Analysis of fEPSP‐spike coupling demonstrated increased values of Top and Eslope50 in the exposed groups. Real‐time PCR analysis showed a significant increase in the mRNA levels of the adult type Nav1.1 Na+ channel subunit and the GluR1 glutamate receptor subunit in the hippocampus of the 700 ppm group at PND 14. Conclusions Our results provide evidence that prenatal exposure to 1‐BP accelerates developmental enhancement of hippocampal excitability in the pups before eye‐opening. The current study suggests that our evaluation method of DNT is applicable to the industrial chemical 1‐BP.

Objectives: Neurotoxicity of 1-bromopropane (1-BP) has been reported in occupational exposure, but whether the chemical exerts developmental neurotoxicity is unknown. We studied the effects of prenatal 1-BP exposure on neuronal excitability in rat offspring. Methods: We exposed dams to 1-BP (700 ppm, 6 h a day for 20 days) and examined hippocampal slices obtained from the male offspring at 2, 5, 8, and 13 weeks of age. We measured the stimulation/response (S/R) relationship and paired-pulse ratios (PPRs) of the population spike (PS) at the interpulse intervals (IPIs) of 5 and 10 ms in the CA1 subfield. Results: Prenatal 1-BP exposure enhanced S/R relationships of PS at 2 weeks of age; however, the enhancement diminished at 5 weeks of age until it reached control levels. Prenatal 1-BP exposure decreased PPRs of PS at 2 weeks of age. After sexual maturation, however, the PPRs of PS increased at 5-ms IPI in rats aged 8 and 13 weeks. Conclusions: Our findings indicate that prenatal 1-BP exposure in dams can cause delayed adverse effects on excitability of pyramidal cells in the hippocampal CA1 subfield of offspring.

This Document, "Guidelines for personal exposure monitoring of chemicals" ("this Guideline"), has been prepared by "The Committee for Personal Exposure Monitoring" ("the Committee") of the Expert Division of Occupational Hygiene & Ergonomics, Japan Society for Occupational Health. Considering the background of the growing importance of personal exposure monitoring in risk assessment and the need to prepare for the introduction of monitoring using personal samplers from an administrative perspective in recent years, the Committee was organized in November 2012. The Committee has prepared this Guideline as a "practical guideline" for personal exposure monitoring, so as to offer proposals and recommendations to the members of the Japan Society for Occupational Health and to society in general. The scope of this Guideline covers all chemical substances and all related workplaces regarded as targets for general assessment and the management of risk. It thus is not to be considered to comment on legal regulations and methodology. The main text provides the basic methods and concepts of personal exposure monitoring, while 31 "Appendices" are provided in this Guideline throughout the series; technical descriptions, statistical bases, and actual workplace examples are provided in these appendices, to assist better understanding. The personal exposure monitoring described as per this Guideline is equivalent to an "expert-centered basic method to reasonably proceed with the assessment and management of risk at workplaces." It is considered that practicing and expanding on this method will significantly contribute in reforming the overall framework of occupational hygiene management in Japan.

This Document, "Guidelines for personal exposure monitoring of chemicals" ("this Guideline"), has been prepared by "The Committee for Personal Exposure Monitoring" ("the Committee") of the Expert Division of Occupational Hygiene & Ergonomics, Japan Society for Occupational Health. Considering the background of the growing importance of personal exposure monitoring in risk assessment and the need to prepare for the introduction of monitoring using personal samplers from an administrative perspective in recent years, the Committee was organized in November 2012. The Committee has prepared this Guideline as a "practical guideline" for personal exposure monitoring, so as to offer proposals and recommendations to the members of the Japan Society for Occupational Health and to society in general. The scope of this Guideline covers all chemical substances and all related workplaces regarded as targets for general assessment and the management of risk. It thus is not to be considered to comment on legal regulations and methodology. The main text provides the basic methods and concepts of personal exposure monitoring, while 31 "Appendices" are provided in this Guideline throughout the series; technical descriptions, statistical bases, and actual workplace examples are provided in these appendices, to assist better understanding. The personal exposure monitoring described as per this Guideline is equivalent to an "expert-centered basic method to reasonably proceed with the assessment and management of risk at workplaces." It is considered that practicing and expanding on this method will significantly contribute in reforming the overall framework of occupational hygiene management in Japan.

For a new desorption method development for working environment measurement, desorption efficiency of organic solvent vapors from an activated carbon was examined using desorption solutions that consisted of anionic and nonionic surfactants. Ten μl of an aqueous solution of isopropyl alcohol or methyl ethyl ketone diluted with distilled water was spiked into a 10 ml vial with a coconut-shell-activated carbon (100 mg). The vial was left for 24 h, and 5 ml a desorption solution was added. Afterwards, the vial was put into an incubator at 60°C and left for 24 h, then the desorption efficiency was determined by analyzing the headspace gas in the vial with a gas chromatograph equipped with flame ionization detector. By adding one or four kinds of nonionic surfactants to the aqueous solution containing two kinds of anionic surfactants, the effect adding nonionic surfactant to the desorption efficiency was investigated, but improvement of desorption efficiency was not observed. On the other hand, desorption efficiency varied depending on the production lot of the coconut-shell-activated carbon tube used as the adsorbent.

Objectives The purpose of this research was to develop and validate an analytical method for rapid determination of the exposure of workers to ortho‐phthalaldehyde (OPA) at the ceiling threshold concentration. Methods A 2,4‐dinitrophenylhydrazine (DNPH)‐silica cartridge was chosen as a sampler. OPA collected by the DNPH‐silica cartridge was subsequently extracted with 5 mL of acetonitrile. A 50‐µL aliquot of phosphoric acid/acetonitrile solution (2%, v/v) was added to 950 µL of the extraction solution and allowed to stand for 30 minutes at room temperature. This solution was then analyzed by high‐performance liquid chromatography tandem mass spectrometry. The basic characteristics of the proposed method, such as recovery, repeatability, limit of quantification, and storage stability of the samples, were examined. Results The overall recoveries of OPA from OPA‐spiked DNPH‐silica cartridges were 93.6%‐100.1% with relative standard deviations, representing the repeatability, of 1.5%‐10.8%. The limit of quantification was 0.165 ng/sample. The recovery of OPA from DNPH‐silica cartridges after 5 days of storage in a refrigerator exceeded 95%. Conclusions The proposed method enabled the determination of the OPA concentration corresponding to the Threshold Limit Value‐Ceiling of 0.1 ppb recommended by the American Conference of Governmental Industrial Hygienists, with a minimum sampling time of 18 seconds (corresponding to a sampling volume of 300 mL at 25°C and 1 atm). Thus, this method will be useful for estimating worker exposures to OPA.

We investigated the adsorption characteristics of volatile organic compounds (VOCs) on the surface of coffee beans after extraction (coffee grounds). Temperature-controllable adsorption equipment of VOC vapor was manufactured, and nitrogen gas containing about 100 ppm of VOC vapor was introduced into a coffee extraction residue. The air in the downstream was analyzed with a gas chromatograph equipped with a flame ionization detector over a period of time. A breakthrough curve was obtained from the analysis of values and time, and the adsorbed amount of each volatile organic compound on the coffee grounds was calculated from a graphical integration of the breakthrough curve. Fourteen VOCs were tested, and the adsorbed amount tended to increase with increases in the boiling point of the VOCs. It was also found that the adsorbed amount of methanol and toluene was affected by the water content in the coffee grounds used in the experiment.

Objective Inhaled 1-bromopropane decomposes easily and releases bromine ion. However, the kinetics and transfer of bromine ion into the next generation have not been clarified. In this work, the kinetics of bromine ion transfer to the next generation was investigated by using cross-fostering analysis and a one-compartment model. Methods Pregnant Wistar rats were exposed to 700 ppm of 1-bromopropane vapor for 6 h per day during gestation days (GDs) 1-20. After birth, cross-fostering was performed between mother exposure groups and mother control groups, and the pups were subdivided into the following four groups: exposure group, postnatal exposure group, gestation exposure group, and control group. Bromine ion concentrations in the brain were measured temporally. Results Bromine ion concentrations in mother rats were lower than those in virgin rats, and the concentrations in fetuses were higher than those in mothers on GD20. In the postnatal period, the concentrations in the gestation exposure group decreased with time, and the biological half-life was 3.1 days. Conversely, bromine ion concentration in the postnatal exposure group increased until postnatal day 4 and then decreased. This tendency was also observed in the exposure group. A one-compartment model was applied to analyze the behavior of bromine ion concentration in the brain. By taking into account the increase of body weight and change in the bromine ion uptake rate in pups, the bromine ion concentrations in the brains of the rats could be estimated with acceptable precision.

Many volatile organic compounds (VOCs) used in work places are neurotoxic. However, it has been difficult to study the cellular mechanisms induced by a direct exposure to neurons because of their high volatility. The objective of this study was to establish a stable system for exposing brain slices to VOCs. With a conventional recording system for brain slices, it is not possible to keep a constant bath concentration of relatively highly volatile solvents, e.g. 1-bromopropane (1-BP). Here we report a new exposure system for VOCs that we developed in which a high concentration of oxygen is dissolved to a perfused medium applying a gas-liquid equilibrium, and in which the tubing is made of Teflon, non adsorptive material. Using our system, the bath concentration of the perfused 1-BP remained stable for at least 2 h in the slice chamber. Both 6.4 and 2.2 mM of 1-BP did not change the paired-pulse response, but fully suppressed long-term potentiation in the dentate gyrus (DG) of hippocampal slices obtained from rats, suggesting that 1-BP decreases synaptic plasticity in the DG at the concentrations tested. Our new system can be applicable for investigating the underlying mechanisms of the neurotoxicity of VOCs at the cellular level.

This Document, "Guidelines for personal exposure monitoring of chemicals" ("this Guideline"), has been prepared by "The Committee for Personal Exposure Monitoring" ("the Committee") of the Expert Division of Occupational Hygiene & Ergonomics, Japan Society for Occupational Health. Considering the background of the growing importance of personal exposure monitoring in risk assessment and the need to prepare for the introduction of monitoring using personal samplers from an administrative perspective in recent years, the Committee was organized in November 2012. The Committee has prepared this Guideline as a "practical guideline" for personal exposure monitoring, so as to offer proposals and recommendations to the members of the Japan Society for Occupational Health and to society in general. The scope of this Guideline covers all chemical substances and all related workplaces regarded as targets for general assessment and the management of risk. It thus is not to be considered to comment on legal regulations and methodology. The main text provides the basic methods and concepts of personal exposure monitoring, while 31 "Appendices" are provided in this Guideline throughout the series; technical descriptions, statistical bases, and actual workplace examples are provided in these appendices, to assist better understanding. The personal exposure monitoring described as per this Guideline is equivalent to an "expert-centered basic method to reasonably proceed with the assessment and management of risk at workplaces." It is considered that practicing and expanding on this method will significantly contribute in reforming the overall framework of occupational hygiene management in Japan.

Objectives: N,N-Dimethylacetamide (DMAC) is widely used in industry as a solvent. It can be absorbed through human skin. Therefore, it is necessary to determine exposure to DMAC via biological monitoring. However, the precision of traditional gas chromatography (GC) is low due to the thermal decomposition of metabolites in the high-temperature GC injection port. To overcome this problem, we have developed a new method for the simultaneous separation and quantification of urinary DMAC metabolites using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Methods: Urine samples were diluted 10-fold in formic acid, and 1-μl aliquots were injected into the LC-MS/MS equipment. A C18 reverse-phase Octa Decyl Silyl (ODS) column was used as the analytical column, and the mobile phase consisted of a mixture of methanol and aqueous formic acid solution. Results: Urinary concentrations of DMAC and its known metabolites (N-hydroxymethyl-N-methylacetamide (DMAC-OH), N-methylacetamide (NMAC), and S- (acetamidomethyl) mercapturic acid (AMMA) ) were determined in a single run. The dynamic ranges of the calibration curves were 0.05-5 mg/l (r≥0.999) for all four compounds. The limits of detection for DMAC, DMAC-OH, NMAC, and AMMA in urine were 0.04, 0.02, 0.05, and 0.02 mg/l, respectively. Within-run accuracies were 96.5%-109.6% with relative standard deviations of precision being 3.43%-10.31%. Conclusions: The results demonstrated that the proposed method could successfully quantify low concentrations of DMAC and its metabolites with high precision. Hence, this method is useful for evaluating DMAC exposure. In addition, this method can be used to examine metabolite behaviors in human bodies after exposure and to select appropriate biomarkers.

Objectives A new desorption method was investigated, which does not require toxic organic solvents. Efficient desorption of organic solvents from activated carbon was achieved with an ananionic surfactant solution, focusing on its washing and emulsion action. Methods Isopropyl alcohol (IPA) and methyl ethyl ketone (MEK) were used as test solvents. Lauryl benzene sulfonic acid sodium salt (LAS) and sodium dodecyl sulfate (SDS) were used as the surfactant. Activated carbon (100 mg) was placed in a vial and a predetermined amount of organic solvent was added. After leaving for about 24 h, a predetermined amount of the surfactant solution was added. After leaving for another 72 h, the vial was heated in an incubator at 60°C for a predetermined time. The organic vapor concentration was then determined with a frame ionization detector (FID)-gas chromatograph and the desorption efficiency was calculated. Results A high desorption efficiency was obtained with a 10% surfactant solution (LAS 8%, SDS 2%), 5 ml desorption solution, 60°C desorption temperature, and desorption time of over 24 h, and the desorption efficiency was 72% for IPA and 9% for MEK. Under identical conditions, the desorption efficiencies for another five organic solvents were investigated, which were 36%, 3%, 32%, 2%, and 3% for acetone, ethyl acetate, dichloromethane, toluene, and m-xylene, respectively. Conclusions A combination of two anionic surfactants exhibited a relatively high desorption efficiency for IPA. For toluene, the desorption efficiency was low due to poor detergency and emulsification power.

Stabilization policies interfere with the dynamic workings of the economic system to which they are applied. As a result, they necessarily generate some dynamic repercussions in the process. This chapter analyzes the dynamic interplay between stabilization policies, capital accumulation, and business cycles. Capital accumulation is an integral part of business cycles. It is not just a component of demand but an addition to the economy’s productive capacity, and, as such, has a lasting influence on employment. As a result, by affecting capital accumulation, stabilization policies can modify the entire shape of business cycles. Assuming a feedback-type policy function, it is shown that, due to the crowding-out effect of fiscal expenditures, too intensive implementation of fiscal stabilization policies leads to instability of the dynamics, but that suitably coordinated monetary policy may be capable of recovering stability.

The purpose of this chapter is to analyze business cycles in a growing economy based upon two principal postulates, namely that (1) fluctuations of involuntary unemployment are an essential constituent of business cycles and (2) accumulation of capital is an integral part of business cycles. Using a macro model which is a close descendant of the monetary growth theory, this chapter establishes the arriving order of the turning points of major economic variables during a cycle, which also serves to resolve the so-called real wage puzzle.

This chapter analyzes cycles and growth using a dynamic version of the Hicksian two-sector model. Two types of friction, nominal wage stickiness and non-shiftability of capital, are present. It is found that sectoral imbalances caused by the non-shiftablilty of capital are corrected in finite time through investment allocation and that the possibility of cycles depends on the speed of nominal wage adjustment. The arriving order of the turning points of some important economic variables is established.

OBJECTIVE Bacteria on the facepiece of a dust respirator were measured just after use and after 24-hours storage at a room temperature after being worn, and bacteria disinfection methods other than ethanol were examined. METHODS The existence of bacteria on a facepiece of a mask that had been worn for about one hour in a laboratory was investigated. In order to eliminate bacteria before use on the next day, five methods of bacteria disinfection were investigated: wiping with a facial tissue impregnated with ethanol as a control; wiping with a facial tissue wetted with tap water; wiping with a dry facial tissue after wiping with one wetted with tap water; wiping with a dry facial tissue after wiping with one wetted with distilled water; and wiping with a dry facial tissue two times. The tests were carried out using silicone rubber sheets plated with bacteria collected from human skin. The disinfection methods that were as effective as facial paper wetted with ethanol, were then assayed on the facepiece of the dust respirator. RESULTS Bacteria were detected on the facepiece immediately after it had been worn. Bacteria were also detected on the facepiece after it had been stored at 25°C for 24-hours after being worn. The methods of wiping with a dry facial tissue after wiping with either tap water or distilled water were almost as statistically effective as wiping with ethanol wetted facial paper. Bacteria on the facepiece were decreased by wiping with a dry facial tissue after wiping with one wetted with tap water. DISCUSSION Colonies of bacteria were detected on a facepiece that had been stored 24 hours after being worn, which suggests that bacteria disinfection just after a respirator has been worn should be recommended. It is very important that the water on the facepiece should be removed after wiping with a wet facial tissue.

Performance and sensor characteristics of a monitor for volatile organic compounds (VOC monitor) using the interference enhanced reflection (IER) method were investigated for 52 organic solvent vapors that are designated as class 1 and class 2 organic solvents by the Ordinance of Organic Solvent Poisoning Prevention in Japan. Test vapors were prepared by injecting 1 to 3 μl of liquid solvent into a 20 l Tedlar(®) bag and perfectly vaporizing them. The vapor concentration was simultaneously measured with the monitor and a gas chromatograph (GC) equipped with flame ionization detector, and both values were compared. The monitor could detect all the solvent vapors that we used. Linear response was obtained between the concentration measured by the monitor and those by the GC. The monitor could detect 1/10 of the administrative control level for 37 of 52 solvent vapors, including toluene and xylenes. For 15 vapors, on the other hand, the monitor could not be used for the working environment measurement because the sensor response was low or the regression lines did not pass through the origin.

Decomposition characteristics of toluene vapor by titanium dioxide photocatalyst and zeolite that are prepared by thermal spraying on an aluminum fiber filter (photocatalyst filter) were investigated. Toluene vapor was injected into a small chamber made of stainless steel, and an air cleaner equipped with the photocatalyst filter was operated. The vapor concentration in the chamber decreased exponentially. The decreasing rate of toluene vapor in the chamber depended on the initial toluene concentration, and the higher the initial vapor concentration was, the lower the decreasing rate was obtained. The decreasing rate was constant during each decomposition experiment, although the concentration decreased with time. To investigate the effect of zeolite on the reduction of the vapor concentration, we compared the decreasing rates of toluene vapor by photocatalyst filters with and without zeolite.The decreasing rate of toluene concentration using the filter without zeolite was larger than that with zeolite. The reason for this would be that photocatalyst decomposed toluene not only in air but also adsorbed in zeolite.

Equilibrated vapor concentrations at 25°C of the tetrachloroethylene-chlorobenzene system were obtained in the presence of air to establish a method for estimating vapor concentrations in work environments where multicomponent organic solvents are used. The experimental data were correlated by introducing activity coefficients calculated by the UNIFAC (Universal Quasichemical Functional Group Activity Coefficient) model. There were four interaction parameters between groups in this solution system, and three had already been determined.However, the fourth parameter--the interaction parameter between ACCl and Cl-(C=C) groups--remains unknown. Therefore, this parameter was determined by a nonlinear least-squares method to obtain the best fit for the experimental data. The calculated values were found to be in good agreement with the experimental values.

Real time monitoring of total volatile organic compounds (TVOC) in rooms of Japanese university buildings was carried out to understand the temporal changes in actual indoor air quality.The TVOC concentrations in seven different rooms, consisting of a lecture room, a seminar room, three laboratories, a computer room and a library, were monitored continuously for 24 h via a personal VOC monitor equipped with a semiconductor gas sensor. An active sampling-thermal desorption method using stainless steel tubes packed with Tenax-TA was also carried out simultaneously to verify the usability of the monitor.The TVOC concentrations measured by the personal VOC monitor were closely correlated with those measured by the active sampling method. The TVOC concentration in all rooms was generally low during the day and increased during the night. This concentration change corresponded to the ventilation cycle in the building. During the day, the TVOC concentration was generally lower than the provisional target criterion (advisable value) of indoor air quality in Japan (400 μg/m³). During the night, however, it exceeded this criterion in several rooms, especially during the summer season.The real-time monitor using a semiconductor gas sensor can provide useful data on changes in the TVOC concentration in indoor air with high sensitivity.

Measurements of organic solvents in the work environment are carried out by either direct sampling using plastic bags/gas chromatography, solid sorbent adsorption using charcoal tubes/gas chromatography, or by a direct reading method using detector tubes. However, these methods cannot always measure the work environment accurately because the concentration of hazardous materials changes from time to time, and from space to space. In this study, the sensor characteristics of a real time monitor using a photoionization detector that can monitor vapor concentration continuously were investigated for 52 organic solvent vapors that are required to be measured in the work environment by the Ordinance of Organic Solvent Poisoning Prevention in Japan. The sensitivity of the monitor was high for the solvents with low ionization potential. However, the sensitivity for the solvents with high ionization potential was low, and the sensor could not detected 7 solvents. Calibration of the sensor using a standard gas was desirable before being used for measurement because the sensitivity of the sensor was variable.

We measured vapor concentrations continuously evaporated from two-component organic solvents in a reservoir and proposed a method to estimate and predict the evaporation rate or generated vapor concentrations. Two kinds of organic solvents were put into a small reservoir made of glass (3 cm in diameter and 3 cm high) that was installed in a cylindrical glass vessel (10 cm in diameter and 15 cm high). Air was introduced into the glass vessel at a flow rate of 150 ml/min, and the generated vapor concentrations were intermittently monitored for up to 5 hours with a gas chromatograph equipped with a flame ionization detector. The solvent systems tested in this study were the methanoltoluene system and the ethyl acetate-toluene system. The vapor concentrations of the more volatile component, that is, methanol in the methanol-toluene system and ethyl acetate in the ethyl acetate-toluene system, were high at first, and then decreased with time. On the other hand, the concentrations of the less volatile component were low at first, and then increased with time. A model for estimating multicomponent organic vapor concentrations was developed, based on a theory of vapor-liquid equilibria and a theory of the mass transfer rate, and estimated values were compared with experimental ones. The estimated vapor concentrations were in relatively good agreement with the experimental ones. The results suggest that changes in concentrations of two-component organic vapors continuously evaporating from a liquid reservoir can be estimated by the proposed model.

1-Bromopropane (1-BP) has been widely used as an alternative to ozone-depleting chlorofluorocarbons in various industries. Although the neurotoxicity of 1-BP has been recently reported, there is little information about the effect of 1-BP on the cells in brain by experimental approach. Here we studied the effect of 1-BP on brain-derived neurotrophic factor (BDNF) expression in astrocytes in vitro. The BDNF mRNA level was remarkably decreased by 1-BP in a human astrocytoma cell line, U251, and in mouse primary astrocytes. The DNA-binding and specific reporter activity of cAMP response element-binding transcription factor (CREB), which is one of the key molecules regulating BDNF expression, were reduced by 1-BP in U251 and/or mouse primary astrocytes. Additionally, protein kinase A (PKA) activity was suppressed by 1-BP in U251. These results suggest that BDNF expression was affected by 1-BP through at least PKA.

Utility functions embodying nonpaternalistic altruism can be regarded as being generated through social interactions among altruistic individuals. As such, they show an important interdependence. Assuming linear altruism, the paper obtains the following results. First, nonpaternalistic altruism has a tendency to unify utility functions. Second, by linearly extrapolating a given structure of altruistic interactions, one can ascertain the extent to which the unification can proceed and its direction. Third, the unification implies narrowing down of the range of conflicting choices but the direction of unification lacks ethical principles. Fourth, the conditions utilitarianism imposes on the structure of altruistic interactions are characterized.

1-Bromopropane (1-BP) has been widely used as a cleaning agent and a solvent in industries, but the central neurotoxicity of 1-BP remains to be clarified. In the present study, we investigated the effects of subchronic inhalation exposure to 1-BP vapor on the function of the inhibitory neurotransmitter system mediated by gamma-aminobutyric acid (GABA) in the rat brain. Male Wistar rats were exposed to 1-BP vapor for 12 weeks (6h/day, 5 days/week) at a concentration of 400 ppm, and, in order to investigate the expression and function of brain GABA type A (GABAA) receptors, total/messenger RNA was prepared from the neocortex, hippocampus, and cerebellum of the control and 1-BP-exposed rats. Moreover, hippocampal slices were prepared, and the population spike (PS) amplitude and the slope of the field excitatory postsynaptic potential (fEPSP) were investigated in the paired-pulse configuration of the extracellular recording technique. Using the Xenopus oocyte expression system, we compared GABA concentration-response curves obtained from oocytes injected with brain subregional mRNAs of control and 1-BP exposed rats, and observed no significant differences in apparent GABA affinity. On the other hand, paired-pulse inhibition of PS amplitude was significantly decreased in the hippocampal dentate gyrus (DG) by exposure to 1-BP, without any effect on the paired-pulse ratio of the fEPSP slopes, suggesting neuronal disinhibition in the DG. Moreover, RT-PCR analysis indicated decreased levels of GABAA receptor beta3 and delta subunit mRNAs in the hippocampus of 1-BP-exposed rats. These results demonstrate that subchronic inhalation exposure to 1-BP vapor reduces the function of the hippocampal GABAergic system, which could be due to changes in the expression and function of GABAA receptors, especially the delta subunit-containing GABAA receptors.

1-Bromopropane (1-BP) induces central as well as peripheral neurotoxicity in workers. We have reported the dysfunction of feedback inhibition (i.e. disinhibition) in the rat hippocampus following exposure to 1-BP at concentrations of 1500 and 700 ppm. For risk assessment, we studied disinhibition of the CA1 region and the dentate gyrus in hippocampal slices obtained from control and 1-BP-exposed (200 and 400 ppm) rats, and determined the bromide concentration in the brain. Granule cell disinhibition was observed after inhalation exposure to 400 ppm 1-BP for 8 or 12 weeks, suggesting that the dentate gyrus was more sensitive than the CA1 region to 1-BP exposure. The lowest observed adverse effect level and the no observed adverse effect level of 1-BP inhalation for disinhibition were 400 and 200 ppm, respectively. The concentration of bromides in the brain increased from 2.9+/-1.5 to 85.0+/-25.4 microg/g-wet brain at week 4 of 400 ppm inhalation, and no further increase was observed even when the exposure period was extended for up to 12 weeks. The relationship between total dose (ppm-h) and the exposure concentration of 1-BP was investigated at different exposure concentrations. Disinhibition and death by inhalation depended on the total dose, and their occurrence appeared earlier as the exposure concentration increased. The results demonstrated a novel model for risk assessment of central neurotoxicity induced by 1-BP inhalation.

Furfural, a colorless liquid used in solvent-extraction processes, petroleum refining and as a rubber additive, has been assigned an occupational exposure limit of 2.5 ppm by the Japan Society for Occupational Health, but an administrative control level for furfural has not been established. In order to conduct effective occupational health management in workplaces where furfural is used, we measured furfural concentrations in working environments and collected urine samples to measure furoic acid levels (one of the principal metabolites), which act as a biomarker of exposure to furfural. The measurements of airborne concentrations in a working environment where furfural or a solution containing furfural was handled were made in 2004. Workers answered a questionnaire on working conditions, urine samples were collected at the end of the workshift, and furoic acid in the urine was measured by gas chromatography/flame ionization detector (GC/FID). The ambient concentrations of furfural during the period were 2.1 ppm in a mixer room and 1.6 ppm in a filling room. The mean concentrations of furoic acid in the workers' urine were 7.7 +/- 7.8 mg/g-creatinine in summer and winter, respectively (normal range: 3 - 60 mg/g-creatinine). The average exposure to furfural per month calculated by multiplying the concentration in the working environment by working hours for a month was 86.4 +/- 108.6 ppm hours/months (mean +/- standard deviation) (range; 0 - 336 ppm hours/month). The relationship between average exposure to furfural and furoic acid in the urine was analyzed by simple linear regression analysis and a positive correlation was found. These findings suggest that furoic acid in urine is useful for biological monitoring of exposure to furfural, and that the measurement of both furfural in the environment and furoic acid in the urine are beneficial in occupational health management of furfural.

Bioaerosols cause sick building syndrome (SBS) and allergy. Many kinds of bioaerosol impactors are used for measurement of airborne microorganism concentrations in Japan. However, because the impactors are set on agar plates, some microorganisms cannot make colonies on the plates because of their lower viability or demands of nutrition. On the other hand, by double staining using ethidium bromide (EtBr) and carboxyfluorescein diacetate (CFDA), both total cells and cells with esterase activities can be detected without incubation. In this study, we calculated total cell concentrations and percentages of cells with esterase activities by the combination of filter sampling and double staining (EtBr and CFDA) from air of a laboratory, a conference room and outdoors. Temperature and humidity in the laboratory were constantly kept by an air conditioner, but in the conference room, an air conditioner was only operated sometimes because of its low frequency of use. There were no significant differences between total cell concentrations and humidity in both rooms, but increase of the percentages of cells with esterase activities depended on rainfall before the samplings (n=15, p

Bioaerosols including bacteria and fungi have been almost unrecognized as pollutants of work environments in Japan. The combination of filter sampling and DNA staining by ethidium bromide (EtBr) was examined for the detection and evaluation of total numbers of bioaerosols, including viable and dead microorganisms, for risk assessment in work environments. With direct counting of microorganisms by EtBr concentrations of total cells were obtained in a shorter time than plate culture, the traditional method for detection of microorganisms. Total cell concentrations (cells/m3) were about 100 times greater than colonized cell concentrations (CFU/m3) in all samples. In some microscopic fields, macro conidia produced from some kinds of fungi were observed, but they were not detected by plate culture. Airborne bacterial 16S rDNA amplified by PCR were determined for their base sequences by DNA sequence analysis and classified by sequence-based homologies. Base sequences from 2 samples each contained 6 common groups of phylum. The combination of filter sampling and direct counting by EtBr staining was shown to be a better method for detecting and evaluating total cell concentrations in the risk assessment of sick building syndrome and allergy.

We studied the change in the hypothalamo-pituitary-adrenal gland (HPA) axis upon adding prior toluene inhalation to our previous formaldehyde inhalation experiments to determine whether short term exposure to relatively high levels of toluene triggers multiple chemical sensitivity (MCS). Data come from immunocytochemical, morphometrical and RT-PCR measurements. Four groups of adult female mice were exposed to differing concentrations (0, 80, 400, and 2,000 ppb) of formaldehyde for 16 hr/day, 5 days/week for twelve weeks, after the mice were exposed intranasally to 500 ppm toluene per mouse for 6 hr/day, for 3 days. We found that the number of corticotropin releasing hormone (CRH)-immunoreactive (ir) neurons was up-regulated according to the amount of formaldehyde as well as inhalation of formaldehyde alone in our previous experiment. The proportion of adrenocorticotropin hormone (ACTH)-ir cells increased according to the formaldehyde concentration, though there was no significant difference between the 400 and 2,000 groups. The number of ACTH-ir cells was higher in the 400 group than in the other groups (0, 80, and 2,000). Expression of ACTH-mRNA was also up-regulated according to the quantity of formaldehyde. The sinusoid in the anterior pituitary showed more dilatation in the 400 and 2,000 groups than in the control group, especially in the 2,000 group. We propose that exposure to toluene prior to inhalation of formaldehyde has no effect on the HPA axis and as a trigger of MCS, although greater sinusoid dilatation was found in the anterior pituitary gland at higher concentrations of formaldehyde.