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The present study describes an investigation on the use and management of ethylene oxide (EO) which is used mainly as a sterilant in medical institutions in a Cabinet-order designated city. Information was obtained from a self-administered questionnaire on safety and health matters related to sterilization with EO gas. The questionnaire was sent to 189 medical institutions including major hospitals and randomly selected clinics. 127 questionnaire were returned and the analysis was carried out for 120 respondents, excluding seven respondents whose answers were found to be inappropriate. The proportion of medical institutions, employing more than 50 workers, in which an occupational health physician and/or health supervisor was appointed was 70% and was lower than for other industries. 1.6% of the employees engaged in EO sterilization activities in the hospitals, whereas in clinics the percentage was as high as 20%. Several problems were found both in the management and work methods with EO: operations were not isolated in 46%; gas leaks and back-streaming of exhaust gas were found in 59% and 41%, respectively; and personal protective clothing was not used in 69%. Improvement was found only for three items among the institutions where an occupational health physician was appointed. These results suggest that good workplace controls and practices are essential for medical institutions using hazardous materials including EO for sterilization.

The prevalence of workers with abnormal findings in periodic general health examinations (PGHEx) has been growing recently in Japan and reached 41.2% in 1998. To clarify the indirect factors related to such an increase in workers with abnormal findings in the PGHEx, we carried out a questionnaire survey on the content of the statutory notification form of results of the PGHEx among a representative sample of 136 Occupational Health Organizations (OHOs). Questions on how those workers with abnormal findings were defined and detected and when the definition and the reference intervals for total cholesterol became available were included. Of the 107 OHOs which answered the questionnaire, 85 were included in the analyses because they actually calculated the number of workers with abnormal findings in each company and helped the employer fill out the notification form. The results revealed that there was no standardized definition of workers with abnormal findings in the PGHEx. Both reference intervals of items in the PGHEx and algorithm in detecting workers with abnormal findings in the PGHEx varied among the OHOs. When detecting the workers, 13 OHOs (15.3%) selected them taking into consideration medical background factors such as previous results of the PGHEx and current medical treatment. From the late 1980s to the early 1990s, many OHOs modified the definition of workers with abnormal findings, and have tended to reduce the upper limit of the reference interval for serum cholesterol. This is mainly due to amendment of the Industrial Safety and Health Law and a new recommendation for a reference interval/value proposed by the related scientific society. Although the prevalence of workers with abnormal findings in the PGHEx has continuously increased, it is not valid to compare the prevalence over the years because of modification in the definition of such workers. The prevalence of workers with abnormal findings in the PGHEx, which is one of the most important indices of the state of occupational health, should be measured by using an objective definition and be compatible with the future system of health examination for Japanese workers.

Analyses of constituents, measurement of concentrations, research of size distributions and scanning electron microscopic examinations were carried out to determine the type and amount of dust generated in a working environment where steel wire coils are unwound. In about a 700 m2 work area unit, stationary samplings, including A-sampling (24 points) and B-sampling (1 point), which are defined by the law, were carried out. The dust concentration was measured by a digital dust indicator. A low volume air sampler was used to determine the conversion factor of the values obtained by the digital dust indicator. Because the result of the dust level by A-sampling and B-sampling were 0.64 mg/m3 and 0.82 mg/m3 respectively, they can both be classified as Control Class 1. A proportion of less than 7 microns of the airborne dust made up about 15 to 20% (volume %) of the total dust in the working environments. Metallic dust and white dust were identified in the accumulated dust. By measuring with a X-ray diffractometry, it was determined that the metal dust constituent was Zn and the white dust constituent was Zn4CO3(OH)6.H2O. By a scanning electron microscopic examination, the scope of the particles was proven to be non-fibrous.

The Material Safety Data Sheet (MSDS) system for the safe management of chemical substances was officially promulgated in 1993 and has been gradually put into practice through administrative guidance in Japan. However, little research has been done on the quality of such data sheets provided from various sectors of industries. We examined two sets of MSDSs obtained from a refractory ceramic plant. In the first survey in 1995, the set of MSDSs was from July, 1992 to March, 1994; and in the second survey in 1997, the set was from April, 1994 to November, 1996. The number of MSDSs examined in these two surveys was 159 and 81, respectively. The number of MSDSs in which "Hazard Identification" was indicated was 100 (63%) in the 1995 survey and 75 (93%) in the 1997 survey. The number of those in which "Toxicological Information (Stability and Reactivity)" was indicated was 81 (51%) and 80 (99%), respectively. The description rates for the essential items, including the above two, were found to be improving.

Recently, because international standardization systems have been set up in many fields, it is necessary for Japanese companies to employ persons who have specific knowledge and techniques in regards to occupational health and safety. In this paper, therefore, we discuss Occupational Health and Safety Practice, Level 4, and try to compare it with Japanese licences. The standard was developed by the Occupational Health and Safety Lead Body (OHSLB) in England. This standard is intended for occupational health and safety practitioners working in general health and safety. We conclude that the training system for occupational health and safety practitioners in Japan must be developed more fully.

A study was made on the recovery from anemia induced by chronic exposure of ethylene oxide. When rats were exposed to ethylene oxide at a concentration of 500 ppm, 6 h a day, 3 d a week for 13 wk, macrocytic normochromic anemia with a high reticulocyte count was observed. The hematological values were also evaluated 4 and 13 wk after the end of exposure and the values were found to have already recovered at 4 wk. We reported previously that anemia induced by ethylene oxide was accompanied with a decrease in glutathione reductase activity and instability of glutathione. In this study, alterations of glutathione redox cycle after the end of exposure were examined. The recovery in the decrease of glutathione reductase was slow and the speed of recovery seemed to be dependent on the life span of erythrocytes of the rats. The decrease in glutathione content completely recovered at 4 wk after the exposure. It was concluded from these observations that anemia induced by ethylene oxide is reversible.

We investigated the toxicity of dichloropropanols (DCPs) in hematological findings and serum chemistry. The solutions of two isomers of DCPs, 1,3-dichloro-2-propanol (DC2P) and 2,3-dichloro-1-propanol (DC1P) were dissolved in saline at the concentration of 100 mg/ml, and 0.1 ml of each solution was subcutaneously injected into male Wistar rats weighing about 200 g. At 6 hours after the injections, in the DC2P group, the number of white blood cells and platelets showed a significant decrease. Transaminases, alkaline phosphatase and lactate dehydrogenase were greatly elevated. Blood urea nitrogen and creatinine also showed a significant increase. There were no changes in the measurements in the DC1P group. These results indicate that there is a prominent hepatotoxicity in DC2P, and that there is a considerable difference in the toxicity present in DC2P and DC1P. Furthermore, in the workplace where DCPs, especially DC2P, is used, the monitoring of the working environment and biological monitoring should be mandatory.

In this study, the effects of methylcobalamin on testicular damage induced by ethylene oxide (EtO) were studied. When Wistar male rats inhaled EtO at 500 ppm, 6 h a day, 3 days a week, for 6 weeks, testicular damage was observed histopathologically and by some other parameters. Subcutaneous injection of methylcobalamin at 500 micrograms/kg, 5 times/week was found to ameliorate the damage. However, the degree of the methylcobalamin effect differed among the parameters examined in this study. Decrease in testicular weight due to EtO exposure was completely prevented by methylcobalamin, and decrease in testicular mature spermatid count and LDH-X activity was fairly well prevented. The degree of prevention of alteration in the epididymis, such as epididymal weight, epididymal sperm count and sperm abnormality rate, was significant but not complete. EtO caused apparent alterations in glutathione metabolism in the testes, but methylcobalamin did not affect such alterations induced by EtO. From these results, it has been determined that methylcobalamin has definite preventive effects on testicular toxicity of EtO.

Male Wistar rats were exposed to ethylene oxide (EO) at concentrations of 50, 100, or 250 ppm for six hours a day, on five days a week for 13 weeks. Dose effect relations of inhaled EO on spermatogenesis were evaluated from testicular and epididymal weights, histopathological changes and lactate dehydrogenase X (LDH X) activity in the testis, and sperm counts and sperm head abnormalities in the epididymis. At 250 ppm, a decrease in epididymal weights, slight degenerations in the seminiferous tubules, decreased sperm counts, and increased numbers of abnormal sperm heads in the tail of the epididymis were found; these were not seen at lower doses. When the abnormal sperm heads were classified into immature types and teratic types, the number of immature heads increased only at 250 ppm. On the other hand, the teratic type had increased at doses of 50 and 100 ppm EO when compared with the control group. Hence, subchronic inhalation of EO at low concentrations affects spermatogenesis in rats.

We investigated the effects of ethylene glycol (EG) on the hepatic drug metabolizing enzymes. The exposed group was given 1% EG solution and the control group was provided with distilled water for 2 weeks ad libitum. The body weight of the exposed group was the same as that of the control group. The liver and kidney weight per body weight did not change. The daily drinking volume for the exposed group on the average showed an increase of 13.5% over that of the control group. Hematologically and biochemically, anemia, liver and renal dysfunction were not seen. The content of the hepatic microsomal cytochrome P-450 in the exposed group showed an increase of 17% over that of the control group, but the contents of cytochrome b5, protoheme and the activities of NADPH-cytochrome c reductase, NADH-ferricyanide reductase did not change. The activities of the hepatic cytosolic alcohol dehydrogenase and glutathione reductase, glutathione peroxidase, glutathione-S-transferase also did not change. These results indicate that the hepatic microsomal cytochrome P-450 takes part in the metabolism of EG.

When Wistar male rats were exposed to ethylene oxide (EtO) at a concentration of about 500 ppm, 6 hr a day, 3 days a week for 2, 6, or 13 weeks, hematological examination showed macrocytic, normochromic anemia with a high reticulocyte count. This result raised the possibility that the hemolytic process was responsible for the anemia. Thus, the following possible causes of hemolysis were investigated with erythrocytes obtained from control and EtO-exposed rats. (1) Metabolism in erythrocytes; (a) Hexose monophosphate cycle: The activity of glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, or glutathione peroxidase was not affected, but the activity of glutathione reductase (GR) significantly decreased and did not recover by the addition of flavin adenine dinucleotide. Reduced glutathione content also decreased and the glutathione stability test was positive. (b) Embden-Meyerhof pathway: Adenosine triphosphate content did not decrease. (c) Lapoport-Luebering cycle: 2,3-Diphosphoglycerate content was not affected. (2) Membrane alterations: Osmotic fragility was not affected and the activity of acetylcholine esterase in the ghost membranes of the exposed group increased. (3) Hemoglobin stability: The heat test and the isopropanol test were negative. GR has an important function in maintaining the reducing power in erythrocytes, and the decrease in the activity caused by EtO induced an alteration of the glutathione stability. Although the mechanism of EtO-induced anemia could not be clearly explained, the inhibition of GR activity might be related to the anemia.

The effects of chronic ethylene oxide (EtO) inhalation on porphyrin-heme metabolism were investigated. When Wistar male rats were exposed to 500 ppm EtO for 6 h a day, 3 times a week for 13 weeks, hemoglobin content significantly decreased, and a normocytic and normochromic anemia was found. In the liver, cytochrome P-450 and protoheme significantly decreased but wet weight, microsomal protein and cytochrome b5 were not affected. The activity of delta-aminolevulinic acid (ALA) synthase increased while ALA dehydratase did not change. The activity of hepatic ferrochelatase decreased time-dependently. Uroporphyrin increased 37% and coproporphyrin tended to increase in the liver. The concentration of protoporphyrin in the liver and erythrocytes tended to increase. Coproporphyrin excretion in the urine showed a 5-6-fold increase while there was no significant increase in urinary ALA excretion. These results indicate that chronic inhalation of EtO causes alterations of hepatic porphyrin-heme metabolism as well as anemia and may affect mechanisms of adaptation to xenobiotics.

アルコール(E)とともに20mg/kgのプロトポルフィリン(PP)をラットに4週間にわたって併用投与し,脂肪肝に及ぼす影響を検討した.液体飼料,アルコール摂取量はE+PP群とE群で差はなかったが,PP投与によりEによる肝腫大は消失し,貧血も改善した.血中脂質ではT-Chol, E-Chol, PLはE群に比し有意に減少し,Eにより著増したTGも減少する傾向があった.肝組織中TGもPPにより減少する傾向にあった.E投与により肝臓中のチトクロームP-450量は著増したが,PPを併用しても,もはや増加しなかった.しかし全ヘム含量はE+PP群でE群に比べ有意に増加しており,ALA-S活性も増加した.PPはEによる貧血と脂肪肝を著明に改善した.その機序として肝組織中のヘム含量が増加していることから,PPが慢性アルコール投与によって低下した肝ミトコンドリア内の呼吸に関与するチトクローム類を回復させることによって,脂肪肝を改善したものと考えられた.

Japanese Industrial Health Organizations (IHOs) have been taking part in medical checkups for employees in accordance with the law of industrial safety and health in Japan. We carried out a questionnaire survey for each IHO in order to learn the actual number of full-time doctors and their proportion of work time. We sent a questionnaire to 112 IHOs (members of International Federation of Industrial Health Organizations) by mail, of which 77 replied (68.8%). In addition, we carried out an interview survey in 3 IHOs. The actual number of full-time doctors was 0 to 51, about half of IHOs have less than 5 doctors/each. Regarding the proportion of work time, among full-time doctors, half of them take part in general health checkups. About 70% of nurses' work time is taken up doing health checkups. The results revealed that the number and the proportion of work time of full-time doctors depends on the characteristics of the area and the background of the organization, for instance, what kind of hygiene services they provide. Depending on the doctors' work style (e.g. full-time or part-time) and their specialities and experience, their work may be shared. Japanese employers are required to report the number of workers with abnormal findings found by medical checkups to the Labor Standards Office. Many IHOs provide service to employers in filling out their reports. Thus, we also asked each IHO about this service. Forty out of the 77 IHOs (51.9%) answered that they are providing statistical analysis and the filling-out service. They count the number of workers with abnormal findings in each company and helped the employer to fill out the report form. Twenty-nine of those 40 IHOs responded that they decided which findings were "abnormal" by using only items that are set by law. However, 7 IHOs reported the fact that they also add some optional items when making the decision. The prevalence of workers with abnormal findings in annual medical checkups, which is one of the msot important indices of the state of occupational health, should be measured by using an objective definition and by being compatible with future systems of medical checkups for all Japanese workers. Although IHOs are endeavoring to improve their level, it will be difficult, and because of diversities in the way of periodical medical checkups among IHOs, there are still many problems to be solved.

Personal and environmental (stationary) ethylene oxide (EO) gas concentrations in gas sterilization facilities were measured at six workplaces in five hospitals. An ethylene oxide gas monitor (3M #3551) was used for both personal and stationary samplings. A gas detector tube was also used for instantaneous sampling. In most workplaces, the personal exposure levels of EO were below the detection limit of the gas monitor. Most of the time-weighted average (TWA) concentrations by the stationary sampling were below the threshold limit value of EO (TLV-TWA = 1 ppm), but in one workplace, more than 4 ppm of EO were detected in front of the sterilizer in a clean room during a 24-hour measurement, although all the personal exposure levels were below the detection limit. Method of aeration after the sterilization was very important for reducing the EO exposure. The EO gas concentrations in two workplaces where sufficient aeration was carried out were below the detection limit in all the stationary samples. In one workplace where insufficient aeration was performed, EO was detected from 16 of 17 stationary samples, and more than 90-200 ppm of EO was determined by the gas detector tube near the worker's face at the moment when the door of the sterilizer was opened and the sterilized materials were removed.

We examined remaining solvents in dry cleaned trousers to estimate the magnitude of environmental pollution. A cleaning solvent of petroleum hydrocarbon was analyzed by means of capillary column mass spectrum gas chromatography. Principal ingredients were identified to be nonane, decane and undecane. The same main components were detected in dry cleaned trousers. Total amounts of evaporated vapor from a pair of trousers (480 g) in 5 days after dry cleaning were nonane (0.73 mg), decane (1.53 mg) and undecane (1.09 mg). The levels on the fifth day were 5%(nonane), 18%(decane) and 32%(undecane) of the first day's concentration, respectively. The half times of the remaining solvents were 1.0 day (nonane), 1.7 days (decane) and 2.7 days (undecane), respectively.

Three neurobehavioral tests and a profile of mood states (POMS) test, which are included in the WHO neurobehavioral core test battery, were applied to 106 workers engaged in manufacturing automotive parts, especially for the purpose of determining the presence or absence of a significant difference in the score between a group of sixty-one workers chronically exposed to organic solvents and a group of forty-five workers unexposed. The scores of both pursuit-aiming and digit-symbol substitution tests were lower (P < 0.02 and P < 0.01, respectively, in analysis of covariance) in the group of exposed workers than in the group of unexposed workers. Furthermore, in the group of exposed workers, the pursuit-aiming and digit-symbol substitution scores showed a positive correlation (P < 0.05 and P < 0.01, respectively) to the fatigue score in the POMS test. On the other hand, the score of the digit span test showed no significant difference between the two groups. No significant correlation was found between the urinary hippuric acid level and the score of each of the three neurobehavioral tests. Therefore, among the exposed workers, the perceptual motor function evaluated in pursuit-aiming and digit-symbol tests seems to be affected. The neurobehavioral tests administered in this study are limited in number and in function, however, the comparison of their scores between the exposed and unexposed workers may suggest the presence of adversive effects of chronic exposure to organic solvents.

Using a fluorometric HPLC method, we determined delta-aminolevulinic acid (ALA) in sera and urine samples from 16 lead workers with blood lead levels ranging from 19 to 107 microG/100 ml. The concentration of ALA in serum correlated highly with the urinary ALA concentration (gamma = 0.957 for ALA mg/1; gamma = 0.967 for ALA mg/g creatinine). The ALA concentrations in the serum of lead workers ranged from 11 to 151 micrograms/1 with a mean of 51 micrograms/1. In addition, the concentrations of urinary ALA (mg/g creatinine) and serum ALA micrograms/1) had a strong correlation with blood lead concentrations (gamma = 0.838 and 0.892, respectively). These data indicate that the measurement of serum ALA, as well as urinary ALA, is very useful for the biological monitoring of occupational lead exposure.

Male ddY mice were exposed to ethylene oxide (EO) at a concentration of 400 ppm, 6 hours a day, 3 days a week for 13 weeks and the effects of EO on the hepatic drug metabolizing enzymes were investigated. The liver and spleen weight per body weight did not change. Compared to the control group, the kidney weight of the exposed group increased while the testis weight decreased significantly. Hematological examination showed macrocytic anemia in the exposed group. Contents of microsomal cytochrome P-450 in the exposed group increased twice as much as that in the control group, while microsomal protein, cytochrome b5, protoheme and NADPH-cytochrome C reductase activity did not change. NADH-ferricyanide reductase activity of the exposed group increased significantly. Among the glutathione related enzymes in the liver, glutathione reductase and glutathione peroxidase activities in the exposed group decreased but glutathione-S-transferase activity increased significantly.

A fatal case of acute fulminant hepatitis following exposure to dichloropropanols is reported. A 59-year-old male worker in a chemical plant developed general malaise, nausea and vomiting several hours after cleaning a tank that had contained dichloropropanols. He had no previous history of hepatic dysfunction. On admission, hepatomegaly was prominent. Because of highly elevated levels of GOT and GPT in the serum, reduced prothrombin time and a lowered consciousness level, a diagnosis of fulminant hepatitis was made. Significant decreases of leukocytes and platelets were also observed. Serum creatinine and BUN were slightly elevated. Although plasma exchanges were conducted on the third and fourth day, the liver functions continued to deteriorate. The patient died on the fifth day. Because dichloropropanols could be detected in the blood specimens obtained at the time of admission, we considered that fulminant hepatitis in this case was attributed to dichloropropanols exposure. To our knowledge, this is the first case of fulminant hepatitis after dichloropropanols-exposure.

The effects of repeated exposure to N,N-dimethylformamide (DMF) on hepatic microsomal monooxygenase system and glutathione metabolism were investigated. DMF was administered to Wistar male rats by subcutaneous (s.c.) injection at 0.5 ml/kg body weight daily for 1 week. Macroscopically, mild liver swelling was observed and liver weights significantly increased after 1 week of exposure to DMF. Hematological changes were not detected. In exposed rats, glutamic oxaloacetic transaminase, glutamic pyruvic transaminase, cholinesterase and total cholesterol significantly increased. Hepatic microsomal cytochrome P-450 and protoheme decreased by 34% and 24%, respectively, while microsomal protein and cytochrome b5 were not affected. NADH-ferricyanide reductase activity decreased by 24% while NADPH-cytochrome c reductase activity showed no change. Glutathione reductase (GR) activity showed a significant decrease after the first injection and remained depressed throughout the study, with no change in glutathione peroxidase (GPx) activity. Glutathione S-transferase (GST) activity showed a significant increase at 3 days after DMF treatment and gradually increased by 66% at 1 week. In a subsequent experiment with a single administration of DMF (4 ml/kg), reduced glutathione (GSH) in the liver was decreased by 28% at 8 h, but recovered to control levels by 24 h. These results indicate that DMF alters the hepatic microsomal monooxygenase system and glutathione metabolism. These findings may greatly contribute to the elucidation of the pathogenesis of DMF hepatotoxicity.

The health and environmental problems of ethylene oxide gas sterilization in a hospital are reported. Eight nurses who had been engaged in the gas sterilization, sometimes operated the auto-sterilizer in an inadequate manner; they exposed more than several hundred ppm of ethylene oxide once or twice a week. The main acute effects on these nurses after massive exposure were headaches, general fatigue and irritation of the eyes and throat. But no signs of polyneuropathy were seen. This survey suggests that there is a great risk of ethylene oxide poisoning while sterilizing instruments in a hospital.

The effects of chronic ethylene oxide (EtO) inhalation on the lens glutathione redox cycle were investigated. When Wistar male rats were exposed to 500 ppm EtO for 6 h a day, 3 times a week for 13 weeks, glutathione reductase decreased significantly in the lens while glutathione peroxidase did not. Glutathione reductase activity decreased time dependently, by as much as 81% after 13 weeks. In spite of changes in the glutathione redox cycle, reduced and oxidized glutathione levels were not affected. Our results raise the possibility that EtO inhalation may produce a cataract via changes in the glutathione redox cycle.

The effect of ethylene glycol on rat hepatic microsomal cytochrome P-450 was studied in vitro and in vivo. The destruction of cytochrome P-450 was not seen in vitro. The addition of 1 mM NADPH also did not change. When ethylene glycol was added to drinking water at a concentration of 1.0% for 7 days, there was no change in the contents of microsomal protein, cytochrome P-450, b5 and heme. While NADPH-cytochrome C reductase activity of the exposed group did not change, NADH-ferricyanide reductase activity increased significantly.

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 sex difference of anemia induced by EO was investigated. Hemoglobin concentrations of both the male and female exposed groups were decreased when compared with each control group, and the anemia in the female exposed group was more severe than that in the male exposed group. Absolute spleen weight increased only in the female exposed group. We have already reported that a decrease of the glutathione reductase activity in the erythrocyte plays an important role in the EO-induced anemia. In the present study, the activity in both male and female exposed groups decreased when compared with each control group, and there was no sex difference in the degree of the decrease. From these observations, we concluded that there was a sex difference in the EO-induced anemia.

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.

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 and the effect of EO on the hepatic monooxygenase system in regards to the sex difference was investigated. Serum GOT of the exposed male rat slightly increased, but that of the female did not change. Contents of microsomal protein and cytochrome P-450 of the male exposed group decreased significantly compared to the male control group, but that of the female exposed group did not change. The change of cytochrome b5, protoheme and NADH-ferricyanide reductase activity of the female exposed group was the same as that of the male. Although NADPH-cytochrome c reductase activity of the male exposed group did not change, that of the female group exposed increased significantly when compared to the female control group. From these observations, we concluded that the effect of EO on the hepatic monooxygenase system was different between male and female.

Male and female Wistar 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 sexual difference in susceptibility of the peripheral nerve to EO was investigated. Both male and female rats of the exposed group showed paresis of the hindlegs, but sexual difference did not affect the degree of this abnormality. In histopathological examinations, axonal degeneration of the myelinated fibers in the peroneal nerve, the nerve to the soleus muscle and in the gracile fascicles of the spinal cord was revealed. The nerve to the soleus muscle degenerated more severely than the peroneal nerve. Sexual difference played no part in the severity of the degenerations in each nerve or in the gracile fascicles. From these observations, we concluded that there was no significant difference in the susceptibility of the peripheral nerve to EO between male and female rats.

The effect of ethylene oxide on rat hepatic microsomal cytochrome P-450 was studied in vitro. Cytochrome P-450, but not b5, was decreased by ethanol. When hepatic microsome was bubbled with ethylene oxide gas, cytochrome P-450 content remained unchanged when compared with CO2 bubbling. The addition of NADPH 1 mM also did not change cytochrome P-450 significantly. The excessive high exposure to 500 mM ethylene oxide also did not affect microsomal cytochrome P-450. These results indicate that ethylene oxide does not destroy directly the hepatic microsomal cytochrome P-450 under these conditions.

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.

Since the end of the nineteenth century, numerous cases of triorthocresyl phosphate (TOCP) poisoning due to accidental contamination of drink, food or drugs have been reported. Following the ingestion of preparations contaminated by TOCP, gastrointestinal symptoms may occur and after an interval of ten to twenty days, a well-known delayed neurotoxicity gradually develops. In general, the initial symptoms are pain and paresthesia in the lower extremities. In most cases, muscle weakness progresses rapidly developing into a striking paralysis of the lower extremities with or without an involvement of the upper extremities. Severe cases show pyramidal signs. The histopathological findings show axonal degeneration in the peripheral nerves and degenerative changes in the anterior horn cells. Degenerative change also occurs in the lateral and dorsal tracts of the spinal cord. The cardinal therapy is physical rehabilitation.

Pyridoxine hydrochloride, 125 mg/kg, 250 mg/kg, 500 mg/kg or 1,000 mg/kg, daily, was intraperitoneally injected into Wistar male rats and its effects on weights and mature spermatid or sperm counts in the testis and the epididymis were investigated. After six weeks administration, weights of the testis and the epididymis in the 500 mg/kg and 1,000 mg/kg groups dramatically decreased and weights of the epididymis in the 125 mg/kg and 250 mg/kg groups also decreased significantly. Mature spermatid counts in the testis and sperm counts in the epididymis decreased in the 500 mg/kg and 1,000 mg/kg groups, and sperm counts in the tail plus body of the epididymis also decreased in the 250 mg/kg group. From these results, it was elucidated that megadoses of pyridoxine induced testicular damage in rats.

Effects of styrene and styrene oxide on delta-aminolevulinic acid dehydratase in rats were investigated, in vivo and in vitro. In the in vivo study, rats were exposed to styrene or styrene oxide intraperitoneally for seven days. delta-Aminolevulinic acid dehydratase in the erythrocyte was inhibited by both styrene and styrene oxide. The inhibition by styrene oxide had a clear dose-response relationship, but that by styrene did not. In the liver, however, these substances did not inhibit delta-aminolevulinic acid dehydratase. In the in vitro study, styrene oxide inhibited delta-aminolevulinic acid dehydratase both in the erythrocyte and in the liver, but styrene failed to inhibit it. These results suggest that styrene is metabolized to styrene oxide, and this metabolite inhibits delta-aminolevulinic acid dehydratase. It is also thought that the discrepancy of inhibition between the erythrocyte and the liver is due to a difference of distribution and metabolism of the substances.

Wistar male rats were exposed to ethylene oxide (EtO) at a concentration of 500 ppm, 6 hr a day, 3 days a week, for 2, 4, 6, or 13 weeks. Testicular toxicity and changes in glutathione metabolism in the testis were investigated. The relative weights of the testes and the epididymes of the EtO-exposed group decreased in a time-dependent manner. Light microscopic examination revealed degeneration and exfoliation of germ cells. Although the severity of damage became apparent over the course of exposure, some seminiferous tubules showed germ cell recovery at 13 weeks compared with 6 weeks. There was no alteration in plasma testosterone concentration. Glutathione reductase (GR) activity decreased during the entire examination period, and recovery from the decrease was not achieved by addition of flavin adenine dinucleotide (FAD). On the other hand, glutathione peroxidase (GPx) activity decreased at 2 weeks, and then increased at 6 and 13 weeks. In spite of alterations in the glutathione redox cycle, the level of reduced glutathione (GSH) in the testes was not affected. Glutathione S-transferase activity, measured with 1-chloro-2,4-dinitrobenzene (CDNB) as substrate, increased at 6 and 13 weeks and, measured with 1,2-epoxy-3-(p-nitrophenoxy)propane, increased at 4, 6, and 13 weeks. These data indicate that chronic inhalation of EtO induces testicular atrophy. Alterations in the glutathione redox cycle and glutathione S-transferase activity might play important roles in the toxicity and the detoxifying mechanism of the testis.

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.