The mechanism of bactericidal action of hypochlorite and chloramine has been a very important and interesting problem to be investigated, but it has been still in an early stage of study. As the development of the investigation of the mechanisms of cytotoxic effect mediated by phagocytosis of neutrophil leukocyte, participation of hypochlorite to the cytotoxic effect and its production by myeloperoxidase in neutrophil granules have got into the spotlight. In the present paper, the mechanisms and roles of biological production of hypochlorite in mammalian cells and tissues are reviewed, and authors want to make clear the mechanisms of hypochlorite action in cytotoxicity and in disinfection.

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The effect of selenium compounds on the transport of methylmercury (MMC) and HgCl₂ was studied by circulating perfusion experiments in an improved in vitro apparatus. When the initial mercury content in the inner solution was 0.5 mM, promotion of mercury transport was observed upon the addition of 0.01 mM selenite. The transport of MMC was greatly increased with addition of increasing amounts of selenite, while in the case of HgCl₂, mercury transport rather decreased with increasing amounts of selenite added. When selenate was added to the inner solution containing MMC, its increasing effect on mercury transport was considerably weaker than that of selenite. Transport of HgCl₂ was slightly increased by the addition of selenate. Accumulation of mercury in the intestine was hardly changed with increasing addition of selenite or selenate in the case of MMC, but increased in the case of HgCl₂. Accumulation of selenium in the intestine was higher with selenite than selenate. The above observations may be closely related to the mechanisms of absorption, distribution, and toxicity of mercury compounds in vivo in the presence of selenium compounds.

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A simple apparatus for the generation of formaldehyde (HCHO) from its standard solution and an animal chamber for the inhalation of HCHO were developed. A linear correlation between the HCHO concentrations of animal chamber and of standard solution was found. By use of these apparatus, the toxic potential of inhaled HCHO in bronchial tissue was investigated histoparhologically in mice. When animals were exposed to 4 or 8 ppm HCHO for 1 h, only the ciliated cells of bronchial mucosa were degenerated concentration-dependently while marked degeneration in both the ciliated and goblet cells was produced after 1 h exposures once a day for 4 days. In the isolated guinea pig trachea experiments, HCHO induced the contraction of tracheal smooth muscle concentration-dependently at 0.03-0.3% but the irreversible relaxation at 1%.

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About 100 μg of 1, 2-dichloroethane was orally given to mice, or was incubated with mouse liver 9000×g supernatant fraction at 37°C for 60 min. Metabolites were extracted by dialyzing liver homogenate against acetone and separated by preparative thin-layer chromatography on an activated carbon plate with water as a development solvent. Each fraction of activated carbon scraped from the plate was monitored for ninhydrin-positive compounds by thin-layer chromatography on a precoated Silica gel G plate in a solvent of n-butanolacetic acid-water (4 : 1 : 1, v/v/v). The first fraction (origin) gave a significant ninhydrin-positive spot. After hydrolysis of this compound with 6 N hydrochloric acid, glutamic acid, glycine, and another product were found. The other product was identified as S-(β-hydroxyethyl) cysteine by mass spectrometry, amino acid analysis and thin-layer chromatography. The ninhydrin-positive metabolite formed from 1, 2-dichloroethane was thus identified as S-(β-hydroxyethyl) glutathione.

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Thimerosal (ThM) resistant bacteria isolated from the scum of discarded vaccines containing ThM were identified as Pseudomonas sp. on the basis of its bacteriological properties. The isolated bacteria were resistant to 1165 μg/ml of ThM and also to 200 μg/ml of mercuric chloride (MC). By incubation of a mixture of ThM and the bacteria, mercury decreased from the supernatant of the culture. ThM incorporated by the bacteria could neither be dialyzed by cysteine equilibrium dialysis nor be detected by a dithizone method. After formalin treatment, the bacteria could not incorporate ThM. ThM, therefore, may be incorporated actively by the bacteria. In the case of MC, however, most of MC seems to be adsorbed on the cell surface immediately after its addition in contrast to ThM. Then incorporared ThM might be localized near the surface of the cell wall, and then enzymatically decomposed to vaporizable form, since the total mercury decreased in the reaction mixture with an increase in inorganic mercury. When sodium selenite (Se), equivalent to ThM, was added to the reaction mixture containing ThM and Pseudomonas sp. and the mixture was incubated at 27°C, total mercury in the reaction mixture did not decrease and inorganic mercury could not be detected in the suspension. It was presumed that Se may bind to inorganic mercury in the existence of cell components, and that it may prevent from vaporizing mercury from the suspension.

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It was found by the tracer technique by using ²⁰³Hg-labeled compounds that Pseudomonas sp. isolated from the scum of discarded vaccines could vaporize mercury from thimerosal (ThM) and mercuric chloride (MC). A reaction mixture, containing ²⁰³Hg-compound and bacteria in phosphate buffer, was incubated at 27°C in outer well of Conway's microdiffusion apparatus. After 24 h, the mercury levels in outer well decreased to about 30% of the initial amount and almost all vaporized mercury was trapped by activated carbon in inner well. When sodium selenite (Se) was added to the reaction mixture containing ThM and bacterial suspension, the amount of mercury trapped by activated carbon decreased and the mercury level in the supernatant slightly decreased after centrifugation of the reaction mixture. From these experiments it was presumed that Se may suppress the uptake of ThM by bacterial cells. When the same experiment was done by using crude extract instead of the bacterial suspension. the mercury contents trapped by activated carbon decreased to the same level as compared to the case of bacterial suspension, but ThM in outer well hardly changed. On the other hand, the trapped mercury contents on activated carbon in the case of MC were almost the same level regardless of the presence or absence of Se. It can be considered that Se may slso suppress the conversion of ThM to inorganic mercury. Mercury trapped by CuI or dithizone powder was extracted with a small quantity of acetone to analyze by alumina-thin-layer chromatography. Detected compounds on the chromatogram showed the same Rf values as those of reference compounds, HgCl₂-dithizonate and HgCl₂-CuI reactant. It is conceivable that ThM was decomposed biologically not to vaporizable organic mercury but inorganic mercury.

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It has been noted that the contents of trace elements in hairs vary with difference of position in the same head, age, sex, hair cosmetic treatment and enviromental pollution. This paper describes the rapid analytical method of calcium in small hair segments (1 cm) using flameless atomic absorption spectrophotometry and the variation of calcium content in the hairs with the permanent wave treatment. Calcium was determined with the rocovery of 99% by ashing in platinum crucible followed by dissolving the residue in water by stirring with the glass covered magnetic spin bar. Loss of calcium was observed when the porcelain crucible or the glass flask was used as ashing ware, and the tefron covered magnetic spin bar caused contamination of calcium. The analytical results obtained by this method agreed with those of the other investigators determined by neutron activation analysis or atomic absorption analysis. In the hairs which had never permanent-waved the calcium concentrations were 200-1000 ppm and showed a general tendency to increase slightly from the root to the distal end of the hair. On the other hand, the permanent-waved hairs showed higher calcium concentrations (2000-4500 ppm). Adsorption of calcium on the treated hairs was dependent on pH, showing that after the hair previously treated with permanent wave reagents were soaked in city water (pH 6.8) calcium content increased and that no significant increase was observed by soaking in acidic calcium solution (pH 3). Calcium adsorbed on the treated hairs was removed by soaking in dilute hydrochloric acid (1→20). The above results suggested that permanent wave treatment is responsible for increasing ionexchangeable calcium in the hair.

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The vaccines expired a term of validity were incubated with thimerosal (ThM)-resistant bacteria and about 95% of ThM content could be eliminated from the suspension. The conditions were as follows ; vaccines 91, bacterial suspension 0.51, and normal broth 0.51 were incubated at 27°C at air bubbling rate of 0.8-1.21/min. ThM was decomposed to vaporize mercury which was trapped by activated carbon. Safety of the air after passing through the tube packed with activated carbon was tested by using mice ; survival numbers and mercury levels accumulated in the organs were compared to the mice inhaling treated or non-treated air. All mice exposed to the air through the carbon tube were alive (10/10) and showed body weight gain (+0.95g) after 4 d incubation. The mercury levels accumulated in organs of mice were the highest in the kidneys, when the carbon trap was used, but with the carbon trap, only 0.2-0.3 μg mercury per wet g was detected in the kidney and lungs. It is very effective way for the protection of environmental pollution to pass through the carbon tube, although a long exposure experiment of mice has not been done. After treatment by this method, residual mercury was detected at a concentration of 2.46±0.62 μg/ml (±S.D. of 18 runs) in the solution.

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It has been recognized that lead poisoning in children in the United States is mainly caused by lead containing paints. In order to clarify whether children in Japan are safe from lead poisoning or not, we investigated lead contents in paints, paints covering pencils, wax crayons, water colors, and those in paint scrapings collected from the buildings of the National Institute of Hygienic Sciences and from its members' houses by the modified A.O.A.C. method. Consequently, considerable numbers of samples containing more than 0.06% of lead, which is the regulatory limit in the United States, were found : 10/31 in paints, 3/49 in paints covering pencils, 0/55 in wax crayons, 3/54 in water colors, and 19/68 in paint scrapings collected. From those analytical data, it was clarified that children in Japan are not always safe from lead poisoning and the further investigation should be undertaken to obtain more exact information.

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