Activated carbon fiber (ACF) fortified with commonly used carbon fiber and felt type unwoven cloth by needle punch method removed hydrogen sulfide (H₂S) effectively under the condition of its moisture content of 80%, 200 ppm of its inlet concentration and 100 h^-1 of its space velocity (SV=flow rate/packed volume) (load=11.01 g H₂SS/kg dry fiber?Eday). Complete removal of H₂S lasted for one month and a half. Although drastic decrease of the removal ratio was found at pH value less than 0.5 indrain water due to the accumulated sulfuric acid(H₂SO₄) resulting from the oxdiation of H₂S in the fabrics, oxidizing ability was recovered by washing out H₂SO₄ in thefiber. A single supply of methanethiol (MT) resulted in the production of dimethyl disulfide (DMDS), but MT was perfectly oxidized to methanesulfonic acid in the mixed supply with H₂S. Dimethyl sulfide(DMS) was not removed even at half inlet sulfur load of MT.

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Clostridium perfringens was applied for an indicator of water pollution. As this strain survives mainly as spore form in water environment, the number of the organismis almost not influenced by chlorination. On the contrary, it was observed that coliforms and enterococcus group are influenced by chlorination. C. perfringens was not detected at the upper stream of rivers and oligotrophic lakes where population was very low. As the population around the source of the water is higher, the number of the microorganisms became larger. The high numbers of C. perfringens, coliforms and enterococcus group were found in the rivers running through the urban areas. The number of C. perfringens was correlated closely to the chemical indicators, such as BOD and nitrogen concentration. It seemed that the cell number of C. perfringensis better indicator than those of coliforms and enterococcus.

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Main route of methane transfer through rice plant in tillering stage, and temperature and light effects on diurnal variation of methane emission were experimented with rice plants grown in pots. Main route of methane emission from paddy soil to the atmosphere was through stems via mature roots of rice plant in the early growth stage. Low methane emissionthrough young stems was not due to its oxidation in their rhizosphere but maybe due to incomplete development of aerenchyma. Diurnal variation of methane emission was observed with its maxima and minima at 5 p.m. and 6 a.m., respectively. Methane emission rates from rice plants grown under different temperature conditions (20, 25 and 30°C) for 2 days showed the positive correlation with temperature (Q₁₀ = 4). The effect of light on diurnal variation was considered to be minor from the comparison of the methane emission rate of 2 days shaded rice plants with that without shading treatment.

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Our knowledge has been very much limited how high-rise and high-densed buildings have influence on residents' physical and mental health and daily behaviors. The authors try to clarify this influence of housing conditions, such as sunlight, ventilation, and damp, on residents' health and daily behavior. Based on a hypothesized model explaining various suggested influences of housing conditions on health and behavior, the authors designed questionnaire sheets. The survey areas are 6 primary school districts in Taito, Koto, Shinagawa, and Meguro Wards in Tokyo City. The survey was conducted on the pupils of the 3rd and the 4th grades in primary schools and their mothers. The questionnaire sheets distributed are 763 in number, and the response was 596 (response rate was 78 percent). The authors analyzed how health and behavior could be related to sunlight access, satisfaction level on neighboring environment, daily behaviors and areal characteristics . As a result, it was shown that health and psychological state were strongly related to sunlight access and satisfaction level about neighboring environment of these four aspects. Housing conditions were related to residents' common cold incidence, tiredness, complexion and goodness at waking up on physical health. Conditions of sunlight and ventilation were related to mental health and daily behaviors. Dailybehaviors were also related to housing condition and areal characteristics. By analyzing mothers' recognition structure on sunlight and ventilation, it was shown that manymothers think these shortages can not be compensated by artificial equipments . Considering the results of the survey, we must emphasize the necessity of taking such methods in urban planning as building density control or providing more open spaces in urbanized areas. Growth management should be the key word to create much healthier cities.

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In inbred C57BL/6N mice (B6, female, 7-weeks old) administered a single intraperitoneal dose of 60μg/kg of 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD), the morphological changes characteristic of apoptotic cell death (i. e., chromatin aggregates, nuclear and cytoplasmic condensations and nuclear fragmentation) in thymocytes were observed in the subcapsular and cortical regions of the thymus. Apoptotic bodies were digested mainly by thymic eqithelial cells and, in part, by macrophages. These changes occurred between 14 to 96 hours after exposure to TODD, followed by a reduction in the size and cellularity of the thymic cortex and a decrease in thymocyte number with a nadir on Day 7. Thymic nurse cells including apoptotic bodies and cytoplasmic vacuoles with or without residual bodies were isolated in vitro from thymuses of TCDD-injected mice by treatment with a mixture of 0.05% trypsin and 0.02% EDTA. This suggests that thymocytes might undergo apoptosis within or on the cytoplasm of thymic nurse cells existing in the subcapsularand cortical regions of the thymus. Thymocyte suspensions from normal 7-weeks old B6 mice, when they were incubated with TCDD (10 nM and 100 nM) for 5 hours at 37°C, produced a chromatin cleavage as well as a ladder of oligonucleosome-sized fragments of DNA (multiples of approximately 200bp) after gel electrophoresis. It was noted that large immature thymocytes remained unaffected in both the thymic cortical tissue and the thymocyte suspension from TCDD-treated mice, as well as in the in vitro TCDD-treated thymocytes. Previously we reported that after TCDD treatment there was a significant decrease in the number and percentage of CD4⁺CD8⁺ subset (which comprised about 80% of total thymocytes) in parallel with thymic atrophy and thymocyte depletion (Environmental Science 3 : 21-36, 1990, in Japanese). Together with this finding the results presented here appear to suggest that TCDD enhances apoptosis at the stage of small CD4⁺CD8⁺ thymocytes in the thymus but not at the stage of large immature thymocytes.

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Six compounds were measured in the breathing-zone air of 100 students at a university in Kanagawa, Japan, between August and October, 1991. Participants carried a personal monitor to collect a 12-h air sample (12:00-24:00) . Mean exposures (μg/m³) of the chemicals were estimated to range from 12.2 to 263 for toluene, 1.59 to 18.2 for ethylbenzene, 4.69 to 50.8 for p-xylene, 2.34 to 20.0 for o-xylene, 1.26 to 582 for p-dichlorobenzene, and 0.598 to 19.2 for tetrachloroethylene. Distributions of the chemicals were log normal. Median levels (μg/m³) were 36 .9 for toluene, 4.39 for ethylbenzene, 12.8 for p-xylene, 5.30 for o-xylene, 36.0 for p-dichlorobenzene, and 2 .43 for tetrachloroethylene. The chemicals, except for p-dichlorobenzene and tetrachloroethylene, were highly correlated with each other in personal air samples, indicating possible common sources of exposure. The risks for the chemicals based on the results were discussed.

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