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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.

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.

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.

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.

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.

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.

Most organic solvents used in the workplace are mixed solvents consisting of several components. It is therefore very important to know the equilibrated vapor concentrations in order to control the work environment. In this study, the vapor-liquid equilibrium for multicomponent organic solvents is estimated by introducing the activity coefficients, which are calculated with the UNIFAC (Universal Quasichemical Functional Group Activity Coefficient) model. For two-component solvents, that is, the toluene-methanol and o-xylene-methanol systems, the calculated values of the vapor fraction and the equilibrated vapor concentrations are in good agreement with the reference ones. For three- or four-component solvents that are used as thinners, the calculated values are also generally in good agreement with the reference ones.

In Japan, working environment measurement is prescribed in the designated workplaces using hazardous materials. Measurements should be carried out periodically and countermeasures are performed depending on the results. By introducing such a system, working environments have remarkably improved. However, in the designated workplaces, measurements should be continued even in work environments found safe. On the other hand, measurement need not be obliged for non-designated workplaces even if hazardous materials are utilized.In the United States of America and many European countries, work environment management and work management are carried out by measuring personal exposure concentrations. In Japan, the Ministry of Health, Labour and Welfare is now discussing the introduction of personal exposure monitoring. However, many problems exist to prevent the simple introduction of American and European methods. This paper describes the brief history, present state and problems of work environment control in Japan, comparing with the systems of American and European countries.

The hood performance of a local exhaust ventilation system is determined by the capture velocity and the air flow rate. The equation proposed by Dalla Valle has been widely used to speculate this relationship. However, Dalla Valle used different formulae for slot and plain opening (rectangular) hoods, and the calculated values near the boundary between the slot and plain opening by these formulae do not always match each other. In this study, we measured capture velocity of four hoods by changing the distance from the hood face for different aspect ratios. We also tried to develop an empirical formula to express a relationship that could be applied to both types of hoods. As a result, it was found that the relationship between air velocity in front of exterior hoods and air flow rate could be expressed as the sum of two exponential functions with distance. In addition, when the hood aspect ratio was less than 9 the values of the capture velocity calculated by the proposed equation were in good agreement with the experimental ones.

Methyl bromide exposure produces disorders of the central and peripheral nervous system. In the literature, there are many neuropathologic studies on the nervous system, especially on the central nervous system, of experimental animals intoxicated with methyl bromide presented. However, in our opinion, a variety of lesions of the nervous system described in the human methyl bromide intoxication have not been well reproduced in the experimental animals. In this study, male Wistar rats were subjected to a 6-hour exposure a day to methyl bromide at a concentration of 500 or 290 ppm 3 days a week for 3 to 8 weeks. The systematic neuropathologic studies of their central and peripheral nervous systems were carried out to reproduce the nervous system lesions in the human methyl bromide intoxication hitherto not produced in the experimental animals. Among the rats exposed to methyl bromide at a concentration of 500 ppm for 10 to 18 days, the axonal degeneration of myelinated fibers at the cervical level of the fasciculus gracilis, which probably corresponds to the degeneration of the spinal posterior column in humans, and the necrosis of the caudate-putamen and atrophy of neurons and pallor of the neuropile in caudate-putamen, thalamus and cingulate cortex, which probably correspond to the degenerative findings of the cerebrum in humans, were found. The rats exposed to methyl bromide at a concentration of 290 ppm for 8 weeks (24 days) did not show any noticeable abnormalities histologically.(ABSTRACT TRUNCATED AT 250 WORDS)

A simple generator for methyl bromide gas has been newly developed by us. For inhalation toxicity studies, until now, there have been few generators capable of producing a constant and stable concentration of methyl bromide gas easily because of its high volatility. The principle of this new generator is based on gas-liquid equilibrium. The gas is generated from the surface of liquid methyl bromide in an evaporator made of a Teflon tube. The generator can produce up to 10,000 ppm of methyl bromide gas in a 0.1 m3 exposure chamber, and the concentration of this generated gas is able to be kept within +/- 0.8% over a long period of time. The generator has proved to be useful for investigating the effects of methyl bromide on health in inhalation toxicity studies.

A head-space gas chromatography (GC) and an ion chromatography coupled with a conductive detector (IC) were used to evaluate levels of bromide ion in urine. The GC method followed by methylation with dimethyl sulfate, showed higher accuracy (2.7% of relative standard deviation) and lower minimum detection limit (0.4 mg/l) compared to the IC procedure of those values which were 8.7% and 1.0 mg/l. The correlation coefficient between the analytical results of 15 urinary samples by the two methods was 0.793. The bromide ion concentrations detected in 36 urine samples of workers exposed to methyl bromide were averaged at 13.3 +/- 7.7 mg/l. The average bromide ion of the non-exposed group was 7.1 +/- 2.1 mg/l (n = 6). Exposed methyl bromide concentrations of workers were monitored with passive samplers during their work shifts (8 hr). No significant correlation between exposed methyl bromide and bromide ion concentrations in urine was observed.

A new adsorption device which is able to detect the breakthrough of organic solvent vapors was developed using a detecting reagent which is packed in a gas detector tube. The organic vapor which leaks from an activated carbon adsorption column reacts with the detecting reagent. The breakthrough is detected by the stain of the reagent. When the humidity of test air was zero, the reagent was stained sharply before the breakthrough was observed. However, in the case of using humid air, the color of the detecting reagent did not clearly change, even after the breakthrough had progressed considerably.

BOD (Biochemical Oxygen Demand) is utilized widely as an index of water quality. However, nitrification is a cause of significant errors in measuring BOD, particularly when a large population of nitrifying organisms are existing in water such as effluents from biological treatment plants. In this case, the use of a nitrification inhibitor is recommended, but it is not used commonly. In order to investigate the amount of nitrogenous oxygen demand (NOD) which is caused by nitrification, BOD with and without inhibitor was measured as samples in the Kitakyushu area. About 70 percent of BOD from the effluents of biological treatment plants was NOD. In the case of influent of biological treatment plant and river waters, 0-39 percent of NOD was contained in BOD.

A reduction of the biological half life of toluene in blood in the simultaneous exposure to toluene and alcohol vapors has been reported. To clarify the cause of this reduction, gene expression of CYP mRNA in liver of rats exposed to bi-component organic vapors was investigated. Wistar male rats were repeatedly exposed to 500 ppm of toluene and 300 ppm of 1-butanol vapors individually and simultaneously by inhalation 6 hours a day, five days a week for 4 weeks. After the exposure, the rats were sacrificed and the livers were collected and homogenized. RNA was extracted from the livers, and gene expression of CYP mRNA was observed by reverse transcription-polymerase chain reaction (RT-PCR). The gene expression of CYP3A2 in the simultaneous exposure group was significantly higher than that in the toluene exposure group. However, there was no significant difference in that of CYP1A2, CYP2B1, CYP2C11, CYP2E1 and CYP4A1.

Antimicrobial activity of hinokitiol (beta-thujaplicin), which is a major component of the essential oil of Chamaecyparis obtuse, against Legionella pneumophila was investigated experimentally. The quantitative antibacterial assay of hinokitiol was carried out by the disk-diffusion method. The test concentrations of hinokitiol were 0.39 to 25.0 micrograms/disk, and the lowest concentrations of hinokitiol that showed growth inhibition against L. pneumophila were 1.56 micrograms/disk on B-SYE agar and 0.39 microgram/disk on B-SYE agar without iron.

The vapor of formaldehyde has been reported to represent a potential health hazard, resulting in respiratory dysfunction. To determine the potential role of alterations in the alveolar macrophages induced by inhalation of formaldehyde, we studied the cytokine production of murine alveolar macrophages. Mice were exposed at 0, 2.5, 5, 10 ppm of formaldehyde for 16 hrs daily, respectively. Durations of inhalation were 7, 14, 21 and 28 days. Immediately after the formaldehyde exposure, murine alveolar macrophages were harvested from the mice. 18 hrs after LPS stimulation, the cytokines (IL-4, IL-10, IFN-gamma, TNF-alpha) were measured in the supernatant of cultured murine alveolar macrophages using the ELISA method. No levels of formaldehyde exposure changed these cytokine productions. Either our dose or duration of formaldehyde exposure might not have been enough to produce significant changes of cytokine production of murine alveolar macrophages. Further experiments with low but longer formaldehyde exposure may be needed to understand the effect of formaldehyde on cytokine production.

Wistar male rats were exposed to 2000 ppm of methyl bromide gas for one hour (single exposure experiment) or 300 ppm of the gas for 6 hours a day, 3 days a week for 4 or 8 weeks (repeated exposure experiment) to investigate the metabolism of inhaled methyl bromide. After the exposure was completed, the bromine ion concentration in serum was measured up to 60 days. The serum bromine ion concentration was determined by a headspace gas chromatography-mass spectrometry after converting bromine ion to methyl bromide by adding dimethyl sulfate in the serum samples. In the single exposure experiment, the bromine ion concentration decreased quickly within one day after the end of the exposure, and then began to decrease gradually. In the repeated exposure experiment, on the other hand, the bromine ion concentration decreased almost exponentially. A two-compartment model was applied to analyze the clearance rate of bromine ion. The biological half time of serum bromine ion was 9.1 days for the single exposure and 5.4 days for the repeated exposure. The amount of cytochrome P450 (CYP) in liver microsomes was measured after the end of exposure. CYP in liver was not significantly different after the repeated exposure but it decreased after the single exposure.

Wistar male rats and ddY male mice were exposed to 500-10,000 ppm of methyl bromide gas up to 8 hours, and the survival time and weights of brain, lung, liver, kidneys, spleen and tests were measured. The survival time decreased with the gas concentration almost exponentially. In general, rats had a longer survival time than mice under the same exposure concentration. Difference of survival time between rats and mice was remarkable at low concentrations but small at high concentrations. Spleen weight decreased significantly and kidney weights tended to increase at 2000 ppm or greater exposure concentrations. Difference between wet and dry lung weight in the exposure group was significantly greater than that in the control group, especially for high concentrations, which suggested pulmonary edema or bronchopneumonia.

Neurotoxicity of 1-bromopropane (1-BP) used as an alternative solvent of fluorocarbons was experimentally studied. Eight rats in the experimental group were exposed to 1-BP at 1500 ppm for six hours a day, five days a week for four weeks in an exposure chamber. Another eight rats in the control group were exposed to room air in a similar exposure chamber as those in the experimental group. During the latter half of the fourth week of exposure, all the rats in the experimental group showed a loss of body weight and ataxic gait compared with control rats. At the end of the fourth week, the rats in both groups were perfused through the ascending aorta and fixed. The cerebellum, medulla oblongata, spinal cord and peripheral nerve were processed for histopathological studies. No statistically significant difference in the frequency of axonal degeneration in both peroneal and sural nerves was found between the experimental and control groups. In the cerebellum, the frequency of degeneration of Purkinje cells in both the vermis and hemisphere was higher in the experimental group than in the control group (P < 0.05). There was no significant difference in the frequency of myelin ovoids in the fifth thoracic and in the third cervical posterior columns of the spinal cord between control and experimental groups. There was also no significant difference in the frequency of axonal swelling in the nucleus gracilis of the medulla oblongata between control and experimental groups. Ataxic gait was considered to be induced by degeneration of Purkinje cells in the cerebellum due to 1-BP exposure. However, degenerative findings of nerve fibers in the peripheral nerve, spinal posterior column and nucleus gracilis of the medulla oblongata due to 1-BP exposure were not evident. At the end of the fourth week of exposure, rats in the experimental group showed loss of body weight and markedly decreased motor activities, and it was considered that they would die if we continued the exposure into the fifth week. Therefore, we feel that our experimental schedule should be reconsidered before undertaking any further studies on the peripheral nerve toxicity of 1-BP.

Concentrations and size distributions of airborne welding fumes in work environments were measured. Samples were collected from 20 workplaces in 13 companies. In all workplaces, the stationary samplings including A-sampling and B-sampling and the personal sampling were carried out simultaneously. The fume concentration in the stationary sampling was measured with a digital dust monitor. A low volume air sampler and an Anderson cascade impactor was also used to determine the conversion factor of the values obtained by the digital dust monitor and the size distributions of the fumes. The personal exposure levels were measured with a TR sampler and a personal cascade impactor. The concentrations by the personal sampling (average: 11.3mg/m3) were much higher than those by the A-sampling (average: 0.4mg/m3 and range: 0.15-0.64mg/m3) but lower than those by the B-sampling (average: 46.8mg/m3, range: 0.66-152.8mg/m3). The mass median aerodynamic diameter (MMAD) of the stationary and the personal samplings were 2.41 microns and 0.80 microns, respectively. Fumes were observed under a scanning electron microscope. Most of the fume particles were sphere in shape but smaller fumes were aggregated and formed larger secondary particles.

Wistar male and female rats were exposed to ethylene oxide (EO) at a concentration of 250 ppm, 6 hours a day, 5 days a week for 17 weeks simultaneously, and the effects of EO on the glutathione metabolism and lipid peroxidation in the liver in regards to sexual difference were studied. Although the liver weight of the male exposed group did not alter, that of the female exposed group increased when compared with the control group. This increase was not accompanied with the alteration of protein content per gram of liver in the cytosol fraction and total homogenate. Among the glutathione related enzymes in the liver, the glutathione reductase activity of both male and female exposed groups decreased compared with each control group, and there was no difference in the degree of the decrease. The glutathione peroxidase activity increased only in the male exposed group. The glutathione-S-transferase activity of both male and female exposed groups increased significantly. In the male exposed group, the activity increased greater than that in the female exposed group. In the male exposed group, the lipid peroxide level in the liver increased slightly but not significantly.

The effects of systemic toxicity including reproductive toxicity of ethylene oxide on female rats were studied. When Wistar female rats were exposed to 250 ppm of ethylene oxide for six hours a day, five days a week for ten weeks, they showed inhibition of body weight gain and paralysis of the hindlegs. Hematological examination revealed macrocytic and normochromic anemia with high reticulocyte counts. The estrus cycle of the exposed group was prolonged and the percentage of the diestrus stage increased. There was no atrophy in the ovary or the uterus. However, the activity of glutathione reductase in the ovary decreased by 18% and that of glutathione-S-transferase increased by 30%. These results indicate that ethylene oxide has a similar effect on both female and male rats and that the female reproductive system is also affected.

A case of optic neuropathy induced by thinner sniffing is reported. A 17-year-old girl, who had been sniffing a lacquer thinner for three months, suffered acute blindness followed by optic atrophy. Brain computed tomography revealed symmetrical low attenuation areas in the bilateral putamen. An analysis of the thinner by gas chromatography showed that its major components in a vaporized state were methyl alcohol and metyhl acetate. The optic neuropathy was induced by these solvents. In the diagnosis of the intoxication of mixed organic solvents, the measurement of each solvent in its vapor phase is considered to be quite important.

Although propylene oxide, which is similar in chemical structure to ethylene oxide, is expected to produce neuropathy, there is no convincing evidence of the degeneration of the peripheral nervous system. To determine the exposure concentration of propylene oxide necessary to produce neuropathy in male Wistar rats, we subjected them to repeated exposures of propylene oxide at concentrations of 500, 750, 1000, 1500 and 2000 ppm. The test rats were subjected to a single 6 hour exposure of propylene oxide at a concentration of 1500 parts per million 5 times a week for 3 weeks. They developed a significant decrease in body weight, abnormal posture of the hindlegs and axonal degeneration of myelinated fibers in the peroneal and sural nerves, the nerves to the soleus muscle, and in the fasciculus gracilis of the spinal cord. Therefore, it was concluded that propylene oxide induces neuropathy in rats characterized by axonal degeneration, similar to that produced by ethylene oxide, and that the exposure to the higher concentration of propylene oxide is more necessary to produce neuropathy than in the case of ethylene oxide neuropathy in rats.

A thermal desorption method is proposed for the measurement of single- and bi-component organic solvents adsorbed on activated carbon. The adsorbed amount was obtained from the measured desorbed amount and the estimated thermal desorption efficiency. Two estimation methods are proposed to determine the desorption efficiency. One is a numerical method, and the other is a simplified analytical method. The numerical method is generally more accurate than the simplified method in estimating the desorption curve and the desorption efficiency, but much time is needed for calculating. By the simplified method, the desorption efficiency could be estimated quickly by using a personal computer. The estimated desorption efficiencies determined by the two methods are compared with the experimental values. A determination procedure of the adsorbed amount by the proposed method is described.

Urinary metabolites of rats exposed to ethylene oxide(EO) were analyzed by gas chromatography-mass spectrometry(GC/MS). Male Wister rats(220-240 g) were exposed to EO for 6 hours. The urine was collected during 18 hours after the exposure and extracted with ethyl acetate. For the water-soluble metabolites, ethanol was added to the urine centrifuged and the supernatant fraction was evaporated to dryness. The residue of the extract was methylated with diazomethane and trimethylsilylated with bis(trimethylsilyl)trifluoroacetamide. Ethylene glycol, 2-hydroxymercapturic acid, 2-methylthioethanol and 2-mercaptoethanol were identified as the metabolites of EO. These results suggest that the inhaled EO was hydrolyzed to ethylene glycol, and conjugated with glutathion to form the mercapturic acid and methylthio metabolite.

A gas chromatographic method was used for determining ethylene glycol in urine. The analytical procedure is based on an azeotropic distillation and on esterification with n-butyl boronic acid. The linear calibration curve was obtained up to 500 micrograms/ml of ethylene glycol. The detection limit was estimated to be 10 micrograms/ml and relative standard deviation was 3.5% for 100 micrograms/ml of ethylene glycol. This method was applied to determine the urinary excretion of ethylene glycol in rats exposed to ethylene oxide at various concentrations (from 50 to 500 ppm). The excretion amounts of ethylene glycol were observed to be dependent on the concentration of ethylene oxide exposed.

The estimation of breakthrough time for multicomponent organic solvent vapors on activated carbon fixed beds is significantly complicated and difficult. This paper describes a simple estimation method of breakthrough time for the first component (foremost breakthrough component) in two- or three-component organic solvent vapors on an activated carbon fixed bed. The breakthrough time for the first component was expressed by the harmonic mean value of the breakthrough times in each pure component. Estimated breakthrough times were compared with the experimental ones.

The effects of chronic exposure of ethylene oxide on the testes were investigated. When rats were exposed to 500 ppm, three times a week for 13 weeks, the testes of the exposed group became remarkably atrophic and their DNA content decreased proportionally. However, plasma testosterone concentration did not significantly change. In the testes the activity of glutathione reductase decreased by 45% and glutathione-S-transferase increased by 64%, respectively. These results suggest that ethylene oxide causes a definite toxicity in the testes and the abnormality of glutathione metabolism plays an important role in its toxicity.