The number of outbreaks of food poisoning in Japan is more than thousand per year. Of the outbreaks which causative agents were determined, 80 to 90% are due to bacteria, such as Vibrio parahaemolyticus, Staphylococcus aureus, Salmonella and so on. In recent years, gastroenteritis due to bacteria other than well known food poisoning bacteria is attracting notice. Therefore, the Ministry of Welfare designated these bacteria as new causative organisms of food poisoning in March, 1982. NAG vibrio is a group of V. cholerae but does not agglutinate with antiserum against somatic (O) antigen of cholera vibrio (O1 V. cholerae). NAG vibrio distributes in natural water, from fresh water to marine water, and some strains cause cholera like diarrhea. V. fluvialis, a slightly halophilic bacterium, inhabits in estuarine and marine area, whereas Plesiomonas and Aeromonas inhabit in fresh water, although they are included in family Vibrionaceae. These bacteria also cause gastroenteritis. Yersinia enterocolitica is widely carried in domestic and wild animals, cause enteritis accompanied with diarrhea and abdominal pain, and is rarely isolated from cases of arthritis, erythema nosdosum and septicemia. The fact that the organism is a psychrophilic bacterium brings forward a sanitation problem in cold storage of foods. Campylobacter jejuni/coli, a microaerobic bacterium, is widespread in animals, especially in avian hosts. The organism known as an etiologic agent for infectious abortion or placentitis also cause acute enteritis. It is said that the etiologic significance of the organism as a pathogen for sporadic diarrheal cases is more important than that of Salmonella. Although gastroenteritis due to enteropathogenic Escherichia coli (EPEC) are well known, the fact that some strains of E. coli other than EPEC also cause gastroenteritis was confirmed in the last decade. These are enterotoxigenic E. coli (ETEC) and enteroinvasive E. coli. ETEC produce two kinds of enterotoxin, heat-stable toxin (ST) and heat-labile toxin (LT). LT has immunological cross reactivity with cholera toxin (CT), and the mechanism of action and molecular construction are also similar to those of CT. Therefore, the investigation of ETEC progressed with that of cholera vibrio, and the progress stimulated the study of other enteropathogenic bacteria described above.

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Recently the amounts of various kinds of wastes have increased, as the industrial production has increased and the living standard has elevated in our country. Consequently, the environmental pollutions have advanced all over the country. In an investigation of the environmental pollution, aquatic sediments are found to be useful because hazardous substances are often adsorbed and concentrated in sediments. Perhaps heavy metals are most extensively studied in hazardous substances. In this review, the emphasis is placed the extraction techniques of heavy metals from sediments, the distribution of heavy metals in sediments, and the evaluation of pollution by heavy metals.

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Biphenyl (BP) was irradiated under a xenon lamp in the presence of various concentrations of NO_X. Some nitrobiphenyl compounds (2-nitrobiphenyl, 4-nitrobiphenyl, 2, 2'-dinitrobiphenyl, 2, 4'-dinitrobiphenyl and 4, 4'-dinitrobiphenyl) were detected among the reaction products by gas chromatography. The organic compounds were tested for mutagenicity towards Salmonella typhimurium TA 98 by means of the plate-incorporation test, and 4, 4'-dinitrobiphenyl was the most potent mutagen among the products identified in the present study. However, the mutagenicity of the photochemical reaction mixture of biphenyl (1 mmol) with NO_X (6 mmol) was about eight times stronger than that of an artificial mixture of intact biphenyl and the identified nitrobiphenyls in the absence of the S-9 microsomal activation system. In summary, unidentified components of the photochemical reaction mixture of biphenyl with NO_X are the major direct mutagens ; the amount of these components increased with increasing amount of NO_X, and reached 54.8% of the total reaction mixture by weight (for 1 mmol BP with 6 mmol NO_X).

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The decrease of the amount of trichlorofluoromethane (F-11) and dichlorodifluoromethane (F-12) by irradiation was studied by gas chromatography (GC) and GC-mass spectrometry (MS). When the sea-water containing both F-11 (14.7 ppm) and F-12 (73.9 ppm) was irradiated with a xenon lamp, 48.8% and 55.1% of them were lost in 25 h, respectively. The benzene extract of the irradiated sea-water contained at least 3 products of which amounts increased with the time of irradiation. GC-MS analysis indicated that bromochlorodifluoromethane (CBrClF₂) and 1, 3-butadiyne (CH≡C-C≡CH) were 2 of the 3 products formed by the irradiation.

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The levels of trichlorofluoromethane (F-11) and dichlorodifluoromethane (F-12) in coastal-water were investigated with ECD-GC using the head space technique. The sample gases of F-11 and F-12 were prepared by transferring F-11 and F-12 into the gas-phase in a flask and by concentrating the gases through a trapping tube. The average levels of F-11 and F-12 analyzed for 12 sampling points were 0.54±0.20 ppt and 0.33±0.19 ppt, respectively. The photolysis of the above coastal-water containing F-11 and F-12 was then conducted by a xenon lamp. The concentration of F-12 in the coastal-water did not decrease significantly, while that of F-11 increased slightly after 20 h of irradiation at the maximum.

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In order to apply an aqueous toluene solution as standard-sample for the detection of toluene in the blood, the present study was carried out. The volatilities of some solvents in blood-sample were gas chromatographically measured by using head space gas method concerning the next problems : the kind of internal standard substance, warming temperature, the shaking effect for the volatilization of solvent, the kind of packing for enclosing head space gas in a vial and the diluting effect of blood with water. As the result, the following method was established. Ethylbenzene (chloroform or 1, 2-dichloroethane) as internal standard was added to vial having a five-fold diluted blood-sample or aqueous standard-sample. The vial was sealed with Teflon-rubber packing and shaken at 35°C for 20 min in water bath. One ml of the head space gas in a vial was subjected to gas chromatography. The concentration of toluene was calculated by comparing the result of blood-sample with that of standard-sample. This method permitted the use of aqueous standard solution and the measurement of toluene was possible over the range of 0.5 to 500 μg/ml in the blood.

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Four spectrophotometric methods (absorbance difference method, absorbance ratio method, total hemoglobin method proposed by Hayashi et al. and alkaline method modified by Katsumata et al.) and gas chromatographic head space method for the determination of carboxy hemoglobin were compared using serially mixed standard samples. Best linearity and reproducibility were obtained by the absorbance difference method which needed accurate wavelength adjustment with narrow band path spectrophotometer. The absorbance ratio method had slightly less accuracy than former method but it is practically good method because even a wide band path spectrophotometer is usable. Total hemoglobin method needed two hours for one sample and linearity and reproducibility were poor. This method should be used only for the decomposed samples to which other method is not able to apply. The alkaline method showed poor linearity and reproducibility. Liberation of carbon monoxide was observed in 100% carboxy hemoglobin sample in both absorbance difference and absorbance ratio methods. Gas chromatographic method showed very good linearity and reproducibility in the samples not containing methemoglobin, but higher estimated values than actual values were obtained in the samples containing methemoglobin.

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The low molecular weight cadmium-binding protein induced in the liver of the fish (giber ; Carassius auratus langsdorfi) by cadmium loading was shown to be a mixture of two isoproteins. The two isoproteins were referred to gibel metallothionein-I and -II (MT-I and -II) according to the order of elution from a DEAE Sephadex column. The molecular weight of the purified metallothioneins was estimated to be similar to that of mammalian metallothioneins by amino acid analyses. Metals in the gibel metallothioneins were mainly cadmium (around 90 mol%), and zinc and copper were present as minor co-existing metals. The SH/metal ratios were 2.9 (MT-I) and 2.2 (MT-II) Amino acid analyses revealed characteristic amino acid compositions which were consistent with the metallothionein concepts ; high cysteine contents (36.8 and 38.2 mol%), without aromatic amino acids and histidine. As relatively abundant amino acid residues in the gibel metallothioneins, lysine, serine and glysine (9.1-11.6 mol%) were present other than cysteine residue. Both of the isoproteins contained a single methionine as in the case of mammalian metallothioneins.

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Effect of humic acid on heavy-metal toxicity to Escherichia coli was investigated. The toxicity was evaluated as growth inhibition, namely an increase in generation or lag phase time, or a decrease in O.D. at stationary phase. With five metals (Co²⁺, Ni²⁺, Cd²⁺, Cu²⁺, Cr⁶⁺), an approximately linear relationship was observed between these parameters and metal concentration. The slope of such straight line obtained with each metal decreased clearly except with Cu²⁺ when E. coli was incubated in the culture medium containing humic acid together with a metal. That is to say, the toxicity of heavy metals was reduced with the humic acid. Gel filtration chromatography of a mixture of each metal and the humic acid showed that these metals had affinity for the humic acid under the growth conditions of E. coli.

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