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.

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The cytochrome P-450-dependent monooxygenase system is involved in the metabolism of both endogenous compounds and xenobiotics. The role of these enzymes in toxicological response is exemplified by an autosomal recessive polymorphism at the cytochrome P-450 2D6 debrisoquine-4-hydroxylase locus, which results in the severely impaired metabolism of many drugs [Gough et al. (1990) Nature 347: 773-776]. The prevalence of this polymorphism (poor metabolizer) differs considerably between ethnic groups. Here we analyzed the P-450 2D6 polymorphism in 25 Japanese and 20 Chinese by DNA-based genetic assay using peripheral leukocyte. Although the phenotype of all the normal metabolizers and 79% of the poor metabolizers could be identified in Caucasians, this DNA-based genomic assay could not predict poor metabolizers in both the Japanese and Chinese. These results indicate that the genetic mechanism of the phenotyped poor metabolizer in Orientals is different from that in Caucasians.

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A reversed-phase high-performance liquid-chromatography method for determining simultaneous quantitation of purine-pyrimidine metabolites, allopurinol and oxipurinol in plasma and urine samples was studied. Separation was optimal with phosphate buffer (10 mmol/ℓ, pH 5.0) containing 1% methanol as an eluent and μ Bondapak C₁₈ as a column. An isocratic separation of a standard mixture of 13 compounds was achieved within 40 minutes with adequate reproducibilities (coefficient of variation: 2.49% for 1.63 μmol/ℓ orotidin-0.12% for 50 μmol/ℓ uridine). A simple ultrafiltration of plasma yielded quantitative recoveries (uric acid: 101.7－107.5%, hypoxanthine: 90.4－102.8%, xanthine: 95.9－99.5%, oxipurinol: 104.4－107.1%, allopurinol: 97.4－103.4%). Compounds were identified by their retention times, absorbance ratios, co-elution with standards and enzymic shifts. In addition to the above compounds, simultaneous quantitation of pseudouridine, uridine, adenine and inosine in the plasma would be possible under the same conditions.

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A survery on sudden unexpected death, that is, death within 24 hours from acute onset, among Japanese workers was carried out. Questionnaires were sent to full-time occupational health physicians who were active members of the Japan Association of Industrial Health at the time of the survey. Though 241 doctors answered (response rate: 61.5%), only 53 of them who had had both sudden death cases and the desire to join in this research co-operated in this survery. During the 5 years of observation (from Jan. 1, 1986 to Dec. 31, 1990), 143 cases of sudden death, 141 males and 2 females, were reported. The mean age was 46.5 (S. D. 10.5) for males. The ages of the 2 females were 31 and 44. Onset took place most frequently at home (55%) and most often during sleep (26%). This may be due to the higher rate not only of onset but of death resulting from acute onset at home and during sleep. Similar to the previous findings, a small peak of incidence was found early in the morning (4 : 00 AM － 9 : 00 AM), although this was not statistically significant. However, the weekly and seasonal variations were a little different from previous reports. In this study, sudden death tended to occur more on Monday, Thursday, Friday, and Saturday (not statistically significant), and as for the seasonal variation, more cases occurred in April, November, and December which were statistically significant. It is suggested that sudden death among Japanese workers may be in some degree attributable to occupational factors because during these months most workers are busier, and they are under more stress in the workplace. Although most causes of death among the 141 males were recorded as cardiovascular accidents (114 cases or 81%), they were rather unreliable because fewer autopsies were performed.

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An X-ray examination of the gastrointestinal tract was performed on 56 patients with systemic cutaneous disease that is often considered associated with internal malignancies. Found were one case of esophageal cancer, two cases of gastric cancer, and two cases of colon cancer. The prevalence of gastric and colon cancer in these patients showed a statistically significant increase compared to the general population. The rate of gastric cancer was 16.26 times higher than the general population and that of colon cancer 32.26. X-ray examination of the gastrointestinal tract in patients with systemic cutaneous disease is useful for detecting malignancy.

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The cutaneous thermal-cooling and -warming detection thresholds were evaluated on the dorsal side of the right distal forearm and on the dorsum of the right foot in 134 normal subjects (66 men and 68 women) without sensory symptoms and signs, aged from 11 to 87 years by using a Thermal Threshold Tester (Vickers Medical International, England). The normative data for the clinical evaluation of the severity and the pathologic process of the sensory disturbance of the patients were obtained. The data obtained included 1) the mean of each threshold and 2) its upper limit value of 95% confidence interval for each decade. The mean of each threshold was significantly increased with aging (P<0.0001). Therefore, the cutaneous thermal-cooling and -warming detection thresholds of the patients with sensory disturbances should be compared with the normative data adjusted for the age of each subject obtained in this study. Based on the evaluation, repeated six times for three weeks, of each threshold of six volunteers (ages from 21 to 66), high reliability of each threshold (intraclass correlation coefficient from 0.78 to 0.96) was observed.

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There are 40 post graduate schools of public health in China, from where 1,400 students are graduating every year. Fourteen percent of them are going into the occupational health field. A total of about 25,000 specialists are now working in the occupational health field. However, this number is only 1 percent of all health workers in China. Facts on the educational resources in China including responsible institutions and programs for such occupational health specialists are introduced and discussed. Finally a program for increasing the number of occupational health specialists in the Eighth Five-year Plan of China is introduced.

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