The biological fate of nitrosamines, known as environmental carcinogens, and their metabolic activation in biological system are reviewed. This article includes the absorption, distribution, metabolism and excretion of dimethylnitrosamine, alkylation of nucleic acid bases with nitrosamines, metabolic activation of dialkylnitrosamines to produce alkyl cations as alkylating agents via α-hydroxylation, and the effects of substituents of α-carbon of dialkylnitrosamines on their biological activities. Emphasis has been placed to α-acetoxyalkylnitrosamines as masked compounds of α-hydroxylated active species. Their chemistry, carcinogenicity, and mutagenicity are compared. Organospecific carcinogenicity of dibutylnitrosamine and N-butyl-N-(4-hydroxybutyl) nitrosamine, urinary bladder carcinogens, are explained in terms of metabolism and metabolic activation.

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Cadmium chloride solution was administrated intraperitoneally in a dose of 1 mg/kg body weight to rats, and the behavior of uptake of cadmium into femur was examined, with the following results. 1) Uptake of cadmium into the bone was higher in metaphyseal bone than in diaphyseal bone. Three weeks after administration, uptake of cadmium into the metaphyseal bone became about 7-8 times that in the diaphyseal bone. 2) Uptake of cadmium into diaphyseal and metaphyseal bones tended to become higher in proportion to the aging of animals, but there was no significant corelation between that and sex and age of the animals. 3) In animals fed a low calcium diet and high phosphorus diet, uptake of cadmium into the bone was significantly higher than in animals fed a normal diet. This result suggested that uptake of cadmium into the bone was closely related to the mobilization of calcium in the bone (bone resorption). 4) The uptake of cadmium into the diaphyseal and metaphyseal bones was similar to that of lead and strontium.

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Distribution and form of radioactive cadmium in the metaphyseal bone of a rat femur were examined after intraperitoneal administration of ¹⁰⁹CdCl₂, and the following results were obtained. 1) Radioactivity was found mainly in the state bound to high molecular compounds in the 105000×g supernatant fraction of the bone. 2) These cadmium-bound high molecular compounds were fractionated sequentially by Sephadex G-75, G-100, and DEAE-cellulose columns, and were compared with metallothionein in the kidney. As a result, these compounds were very similar to metallothionein in points of the charge and molecular size. 3) From the in vitro experiments on binding, it was found that these compounds were induced after administration of cadmium.

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A method for the determination of tin by atomic absorption spectrophotometry utilizing stannane-argon-hydrogen system was studied. Using an arsine generator (Nippon Jarrel-Ash Instruments Arsenic Measurement Unit ASD-1A), stannous chloride was reduced to stannane in an acidic condition with sodium borohydride tablets prepared by molding with kaolin. The amount of sodium borohydride added and the concentration of hydrochloric acid in the reaction mixture were the most important factors to produce stannane quantitatively. The addition of sodium sulfate to the sample was effective to prevent the gas from remaining in the mixture, giving the reproducible values. Though arsenic, antimony, nickel and copper ions interfered with the determination, it was eliminated by the addition of potassium iodide to the sample. The detection limit was 0.1 μg, and water samples fortified at 0.11 ppm of stannous chloride were analyzed at recovery of 95-102%.

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Trace neutral organic substances in raw sewage (influent) and secondary effluent (effluent) were investigated to reveal the fate of organic substances in the environment by gas chromatography-mass spectrometry (GC-MS) technique. Water samples (influent : 5 l ; effluent : 50 l) were separated into the filtrate and unfilterable matter through a Teflon filter having 1 μm pore size, under added pressure (1-3.2 kg/cm²). Organic substances in unfilterable matter were extracted with benzene-ethanol (1 : 1) in a Soxhlet extractor for 24 hr. The filtrate was passed through a column (1.5×12 cm) of Amberlite XAD-2 resin (20-50 mesh) and organic substances adsorbed on the column was eluted with 150 ml of ether. The ether extract was concentrated to below 1 ml in a Kuderna-Danish evaporator. The concentrate loaded on the top of a silica-gel (100-200 mesh) column (1×20 cm), was fractionated in turn with 20 ml of isooctane, 25 ml of isooctane-benzene (1 : 1), and 15 ml of benzene-methanol (1 : 1). Determination of normal alkanes (C₁₈-C₃₃) and polycyclic aromatic hydrocarbons (biphenyl, acenaphthene, 2, 3-dimethylnaphthalene, fluorene, phenanthrene, pyrene, benzo [a] fluorene, anthracene, benzo [b] fluoranthene, and benzo [a] pyrene), which were respectively present in the isooctane and isooctane-benzene fractions, were performed by mass fragmentography. A number of polar organic substances, including plasticizers (dialkyl phthalates, dialkyl adipates, and dialkyl carbonates) and sterols (coprostanol, cholesterol, campesterol, and sitosterol) were found in benzene-methanol fractions by a computerized GC-MS system.

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Chemical form of cadmium in rice protein was examined in order to evaluate the toxicological effect of cadmium in rice. 1) Glutelin, one of rice proteins, was purified from commercial rice (Cd 0.10 ppm) and cadmium-polluted rice (2.2-2.5 ppm), resulting in 8 times increase in cadmium content to 0.8-1.2 ppm and 13-20 ppm, respectively. Content of zinc (117 ppm), lead (3.4 ppm), and copper (60 ppm) in the glutelin preparations from cadmium-polluted rice increased, but that of manganese (3.0 ppm) and organic phosphorus (235 ppm) decreased. 2) Glutelin-^115mCd complex was prepared from purified glutelin and inorganic ^115mCd salt. The cadmium content of the synthetic complex was found to be almost constant in several preparations and remarkably high (2000 ppm). The complex was stable in an alkaline medium but unstable in an acidic medium, dissociating 50% of cadmium at pH 4.0. The complex was stable against heating at 80° for 1 hr. When the complex was dialyzed against various solutions of alkali metal salts, amino acids, and metalchelaters, the complex dissociated 50% in the presence of 3×10^-4M EDTA, but stable against alkali metal salts, amino acids, and some other chelaters in a final concentration of 1×10^-2M. The complex dissociated completely by the addition of Hg²⁺ and Cu²⁺, and partly by the addition of Cd²⁺, Mg²⁺, Pb²⁺, and Zn²⁺ in the descending order, and was stable against Ca²⁺, Ba²⁺, and Mn²⁺ in a final concentration of 1×10^-2M.

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Bacterial mutagenicity of five hair dye intermediates was examined after oxidation by hydrogen peroxide under alkaline condition (pH>10), using Salmonella typhimurium TA98 as the tester strain. Hair dye intermediates tested were p-phenylenediamine, p-toluylenediamine, o-nitro-p-phenylenediamine, and 2, 4-diaminoanisole. In the case of oxidation of p-phenylenediamine, m-phenylenediamine, or 2, 4-diaminoanisole, the mutagenic activity of aromatic diamine varied with the amine concentration in the reaction mixture. Similar effect was also observed with hydrogen peroxide. A lower mutagenic activity was observed when a lower concentration of amine or hydrogen peroxide was employed. Such a concentration effect was not significant in the oxidation of p-toluylenediamine and o-nitro-p-phenylenediamine. In the case of oxidation of amine mixtures, the derived mutagenic activity varied markedly with the molar ratio or the concentration of constituent amines. Therefore, the mutagenic activity of oxidative hair dyes might depend not only on the kind of hair dye intermediates in hair dye preparations, but also on their concentrations.

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Benzo [α] pyrene in soil was determined by gel chromatography and spectrofluorometry with good results in terms of simplicity, reproducibility, and accuracy. Benzo [α] pyrene in the soil samples was extracted with 120 ml of benzene-methanol (5 : 1) mixture in a Soxhlet apparatus and then clean-up was made by alumina (moisture content 7% (v/w)) column chromatography with hexane. Benzo [α]-pyrene was fractionated from this extract by Sephadex LH-20 column (1×25 cm) using isopropanol as the mobile phase. Effluent was collected in 5 ml fractions over the range of 35 to 50 ml, and benzo [α]-pyrene was determined by spectrofluorometry, by the base line method. Benzo [α] pyrene content in the soil determined by this method was 1.3-17.9 ppb in hilly and seaside areas, 107-486 ppb in urban area with extremely heavy traffic, and 32 ppb in the control area with light traffic. No apparent correlation was found between particle size of soil and distribution rate of benzo [α] pyrene.

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In order to study the mechanism of the placental transfer of methylmercury, effect of 2-deoxy-D-glucose and deoxypyridoxine on the transfer of methylmercury to the fetus across the placenta was examined. Pregnant rats were divided into three groups, group A, given 2-deoxy-D-glucose and methylmercury, group B, given deoxypyridoxine and methylmercury, group C, given methylmercury alone. Mercury content in each placenta and fetus was determined. The ratio of fetal mercury content to placental mercury content in both A and B groups was significantly lower than that in C group. It was found that 2-deoxy-D-glucose and deoxypyridoxine inhibited placental transfer of methylmercury. Therefore, it was suggested that one of the mechanisms of the placental transfer of methylmercury was an active transport which was related to amino acid having SH group such as cysteine.

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An improved procedure for the gas chromatographic determination of dibutyl-hydroxytoluene (BHT) in butter was proposed. On hexane extraction of BHT, addition of ammonia water was extremely effective for raising the recovery of BHT. At the spikage levels of 10 and 100 ppm of BHT, recovery was around 50% without ammonia water treatment, while it rose to more than 94% with ammonia water treatment.

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Survey was made of sea water pollution along the seashore of Kei-Yo industrial area (Chiba prefecture) for the 12 years, 1965 to 1976. The values of chemical oxygen demand (COD), NH₄-N, and NO₂-N were examined with the lapse of time. The peak of COD value was found from 1971 to 1973, and then the value showed the tendency to decrease a little. The value of NH₄-N at Station 1 and Station 2 tended to increase remarkably from 1965 to 1976, and thereafter, to reach a plateau. The value of NO₂-N at Station 1, Station 2, Station 3, and Station 7 showed the tendency to increase slowly from 1965 to 1976.

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