Methylmercury is an environmental pollutant well known as a cause for a severe neurologic symptom. This review summarizes recent studies of tissue transport mechanism of methylmercury in experimental animals. Methylmercury has high affinity for sulfhydryl groups such as glutathione (GSH ; γ-glutamylcysteinylglycine) and methylmercury-GSH complex has been detected in animal tissues. GSH is a major intracellular nonprotein sulfhydryl compound in several animal tissues and plays a key role in detoxication and elimination of many xenobiotics, which form GSH-S-conjugates enzymatically, in cooperation with GSH-metabolizing enzymes. In this review, the role of GSH and GSH-metabolizing enzymes in metabolism of methylmercury are discussed in relation to the mechanisms of the transport, accumulation and excretion of methylmercury which reversibly binds to GSH.

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In this paper, the following items relevant to bioconcentration of organic chemicals in fish were reviewed and discussed : 1) mechanism, 2) structure-activity relationship (SAR) and 3) a new theoretical approach to describe bioconcentration potential of a variety of organic chemicals in fish. It was clarified that : 1) bioconcentration phenomenon could be understood from a thermodynamic viewpoint, 2) however, no theoretical SAR approach based on the mechanism could be found so far, except 3) a new theoretical method, which was developed from the consideration on quantum-chemical polar and non-polar interactions of a compound with a fish tissue and water by using Fujita's Σi and Σo. In the new method, there were observed fairly good correlations of logarithm of bioconcentration factors (logBCF) to Σi and Σo (e.g. r²=0.962, n=21). Applicability and limitation of the method were also discussed and verified using a variety of organic chemicals.

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"Standard for School Environment and Hygiene" was established in 1964 to keep students healthy and comfortable to study at school. In the last 30 years, science and technology have greatly progressed and the hygienic states have been very much improved. Many laws and standards have been newly established and revised. The standard had not gone well with the present hygienic states and other laws and standards. The standard had been required to be revised, and was finally revised in June, 1992. This article gives comments on the rivised standard.

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The antioxidative effects of vitamin E (VE) on the administration of potassium bromate (KBrO₃) were examined. Five-week-old SPF-SD male rats were fed the VE enriched diets containing 250 or 1000 ppm VE in commercial diet (CE-2, VE 70ppm) for 4 weeks. KBrO₃ was given in drinking water for 4 weeks at the concentration of 1000 μg/ml and the following results were obtained. 1. KBrO₃ administration inhibited the gain in body weight, while it increased the weight of kidney in rats. 2. The contents of urea nitrogen (UN) and creatinine in the serum increased remarkably and the kidney injury was observed in the groups with KBrO₃ administration. 3. The activities of alkaline phosphatase (EC 3.1.3.1, ALP) and γ-glutamyl transpeptidase (EC 2.3.2.2, γ-GTP) in the kidney cytosols decreased to be about 60-70% of those in control groups. 4. The thiobarbituric acid reactive substances (TBRAS) contents in the liver and kidney homogenates decreased in the groups with VE enriched diet administration.

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Thirty two organic pesticides were screened for the reaction with ozone in water and their products were identified. Organophosphorous, acid amides, thiobencarb, isoprothiolane and pendimethaline showed high reactivity with ozone. Reactivity of N-methylcarbamates depended on the alkyl group substituted on the benzene ring. Simazine, Oxadiazon and diphenyl ethers showed low reactivity. Some pesticides with electrophilic groups fully substituted on the benzene ring showed less reactivity with ozone. From the result of the identified ozonation product, oxidation of thiophosphoryl bond, oxidation of side-chain of alkyl group and N-alkyl group, dealkylation, hydrolysis, dehalogenation etc. were considered to occurr. Most organic pesticides tested were not completely decomposed into inorganic compounds such as CO₂ by ozonation. These results suggested that the decomposed products of pesticides remain in water after treatment with ozone at low concentration.

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Pentachlorophenol (PCP), used as an organochlorine herbicide, has toxicity related with active oxygen species such as the strand break of DNA possibility. It was recognized by the thiobarbituric acid (TBA) method and the oxygen electrode method that active oxygen species, superoxide and hydroxyl radicals, were produced with the metabolism of PCP in a microsomal system in vitro. The TBA-reactive substance (TBARS) content in the reaction mixture and the rate of oxygen uptake were correlatively increased by the addition of PCP. Moreover, the liver weight, the TBARS content and GSSG content in the liver of mice increased and flavin content in the liver and the enzyme activities in the liver cytosol of mice decreased after the administration of PCP. Each parameter was correlatively changed by the dose of PCP. We considered that the active oxygen species, superoxide and hydroxyl radicals, were produced with the metabolism of PCP in microsome and the lipid peroxidation was related with the hepatic toxicity of PCP in vivo.

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Recently, the environmental pollution by pesticides applied to golf courses has been paid attention as a social problem in Japan. Therefore the concentrations of nineteen pesticides in water and atmosphere samples were measured around golf courses in Kanagawa prefecture from 1990 to 1992. Diazinon, simazine, isoprothiolane, flutolanil, propyzamide were detected in many sampling points at a higher level, although the concentrations in water samples did not exceed the guideline values which were published by Environmental Agency. Moreover, isoprothiolane and flutolanil, whose solubilities in water were high, were easily detected in water environment. On the other hand, benfluralin and fenitrothion, whose volatilization rates were large, were easily detected in atmospheric environment. The concentration of tolclophosmethyl in effluent increased rapidly due to the rain fall after it was sprayed.

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Determination of tris (2-butoxyethyl) phosphate (TBXP) in household products (textiles and some kinds of household wax products) was examined by capillary gas chromatography using a flame photometric detector (FPD). A simple and successfully cleaned up preparation using the difference in liquid-liquid partition behaviour has been developed for the determination. The detection limit by this method was 40 pg. For the determination of TBXP in textiles, TBXP were extracted from samples with methanol under reflux at 70°C. For the removal of polar materials, distilled water was added to the extract, and TBXP was extracted into dichrolomethane from the methanolic phase. After evaporating the organic solvent, the residue was dissolved in n-hexane, and applied to the GC. The recovery of TBXP added to textiles at the amount of 2000 μg was 99% in average. For the determination of TBXP in household wax products, samples were dissolved in n-hexane and were washed 3 times with distilled water to remove polar materials. For the removal of nonpolar materials, TBXP was extracted from the n-hexane phase into acetonitrile. After evaporating the organic solvent, the residue was dissolved in n-hexane, and applied to the GC. The recovery of TBXP added to the household wax product at the amount of 2000 μg was 97% in average. A large amount of TBXP (over 10000 μg/g) was detected in 2 out of 6 brands of floorfinishes, but not in all 3 brands of flame retardant finished curtains by this proporsal method.

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A preliminary study has been carried out for the evaluation of the exposure of human body to carcinogens/mutagens in daily life based on the estimation of mutagenic activity of urine. Blue rayon extracts of urine samples were assayed with Salmonella strains TA98 and YG1024 under the presence and absence of a metabolic activation system (S9 mix). The mutagenic activity was not enhanced by β-glucuronidase treatment. YG1024 was about 10 times sensitive compared to parent strain TA98, and high correlation was observed between the results by both strains. It was capable to monitor time-course variation of mutagenic activity of urine by the usual pre-incubation method with YG1024. Some urine samples showed very potent mutagenic activity in the absence of S9 mix, which had not been reported previously. Mutagenic activity increased after smoking (smoker) and after taking meals like roasted or fried meat (non-smoker) in the presence of S9 mix. It has been suggested that the measurement of mutagenic activity of urine is useful for the evaluation of the exposure of human body to carcinogens/mutagens.

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The inactivation rates of poliovirus (Lsc, 2ab strain) suspended in cell maintenance medium (MEM) and in phosphate buffer salt solution (PBS) with sodium hypochlorite (NaOCl), dichloro-, and trichloro-isocyanurates (2Cl-ICA, and 3Cl-ICA) and monochloramine (NH₂Cl), 0.1-2.0 mg/l as available chlorine, were compared in the same conditions at pH 7 and 20°C. The formation of combined available chlorine (CA-Cl) with the virus suspension and the efficacy of the formed CA-Cl on the virus were studied. The amount of CA-Cl formed in the MEM suspension was greater than that in the PBS suspension and the virus was inactivated rapidly with free available chlorine (FA-Cl). In the PBS suspension containing 0.4 mg/l of chlorine, only a part of the chlorine convert to CA-Cl and more than 99% of the virus was inactivated in 3 min. In the MEM suspension containing the same concentration of chlorine, all of the chlorine was converted to CA-Cl and the inactivation of virus was not observed in 5 min. In 2.0 mg/l of chlorine with MEM suspension, about a half of FA-Cl remained and 99% of the virus was inactivated in 1 min. In 0.4 mg/l of NH₂Cl, only 20% of the virus was inactivated in 5 min. The differences of CA-Cl formed in the virus suspension will give a significant variation in virus inactivation. There were no difference in CA-Cl formation in the virus suspension and the inactivation rate of the virus between hypochlorite and chloroisocyanurates.

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Metabolism and toxicity of acid phosphate esters were studied in the rat. Diethyl phosphate (DEP), diethyl thiophosphate (DETP) and diisopropyl phosphate (DIPP) were administered to rats at a dose of 1 g/kg. DEP-applied rats excreted inorganic phosphate and organic phosphate in the 24 h urine at amounts of 53% and 13%, of the dose respectively. DETP-treated rats excreted inorganic phosphate and organic phosphate in their urine at amounts of 18% and 10%, of the dose respectively. DIPP-treated rats excreted inorganic phosphate and organic phosphate in their urine at amounts of 8% and 9%, of the dose respectively. The DETP-treated rats showed symptoms such as salivation, lacrimation and tremors. DETP intensely inhibited cholinesterase in rat brain homogenate, and DEP weakly inhibited the cholinesterase activity. On the other hand, DIPP did not inhibit the cholinesterase activity. The inhibition of cholinesterase induced by DETP was higher than that of diazinon.

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The inactivation rate of poliovirus (Lsc, 2ab strain) suspended in a cell maintenance medium (MEM) and in phosphate buffer salt solution (PBS) with chlorine dioxide (ClO₂), and chlorite ion (ClO₂^-), of 0.4, 1.0 and 2.0 mg/l as available chlorine were studied at pH 7 and 20°C. The residual ClO₂ and ClO₂^- formed in the test solution were determined. The decrease of residual ClO₂ and the formation of ClO₂^- in MEM virus suspension were greater than those in PBS virus suspension. In the lower concentration of ClO₂ (0.4 mg/l), the decrease of ClO₂ in MEM virus suspension resulted in a slower inactivation. With 2.0 mg/l of ClO₂, 99% of the virus was inactivated in about 2 min in both virus suspensions. Chlorite ion (2.0 mg/l) had little effect on the inactivation of the virus in 15 min contact. The inactivation rate with 2.0 mg/l of ClO₂ was almost the same with that with 0.4 mg/l of HOCl reported in a previous paper. The similar inactivation efficiency may be due to almost the same redox potentials (E₀ (V)) of ClO₂ and HOCl, and due to the equal oxidizing capacities of 2.0 mg/l of ClO₂ and 0.4 mg/l of HOCl in the test solution in the neutral pH range.

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Genotoxicity of 13 mutagens was tested by a Drosophila DNA-repair test. Although strong mutagens such as aflatoxin B1, sterigmatocystin, 2-(2-furyl)-3-(5-nitro-2-furyl) acrylamide, 2-amino-3-methylimidazo [4, 5-f] quinoline, 2-amino-3, 4-dimethylimidazo [4, 5-f] quinoline, 2-amino-3, 8-dimethylimidazo [4, 5-f] quinoxaline, 3-amino-1, 4-dimethyl-5H-pyrido [4, 3-b] indole, 3-amino-1-methyl-5H-pyrido [4, 3-b] indole, and 1, 8-dinitropyrene showed positive results, methylglyoxal, formaldehyde, kojic acid, and hydrogen peroxide gave negative outcome. The ability of larval S9 fraction to activate or inactivate mutagens was monitored in the umu test. In the presence of larval S9, AFB1, IQ, Trp-P-1 and Trp-P-2 induced the umu gene expression, depending on their genotoxicities in the DNA repair test. In contrast, the genotoxicities of AF-2 and methylglyoxal in the umu test were diminished in the presence of S9 fraction. These results suggest that the genotoxic potency of a compound in the repair test is affected at least partly by metabolism in the larvae.

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The distribution of total mercury in the ambient atmosphere of Seoul during the period April, 1988 to March, 1989 was evaluated. The method used in this study involves absorption of gaseous mercury species in the atmosphere on Chromosorb^R A coated with gold based on gold amalgamation. The trapped mercury was thermally released and determined by atomic absorption spectrometry. Air sampling was carried out at 8 points spread over Seoul and classified into 3 groups-within a 5 km, 10 km, 15 km radius from the city center. Three rural points which represented sparse population and little industrial activity were also studied for comparison. The atmospheric mercury concentrations in Seoul ranged from 5.0 to 88.8 ng·m^-3 (mean 25.1 ng·m^-3), while those in rural areas ranged from 1.0 to 7.0 ng·m^-3 (mean 3.8 ng·m^-3). The distribution of mercury depending on the distance from the urban center was evaluated and seasonal, diurnal altitudinal variations of atmospheric mercury were also described.

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The amount of urinary hydroxylysine glycosides (Hyl-Gs) is an index of collagen metabolism. The diurnal and day to day variations in the urinary excretion levels of Hyl-Gs and the effects of diet, especially the intake of a large amount of protein on them, were investigated. The diurnal variation in the urinary excretion levels of Hyl-Gs was within the range of healthy controls ; on the other hand, the day to day variation in the urinary excretion levels of Hyl-Gs was not observed. Although the urinary excretion of Hyl-Gs follows the same physiological variations as urinary hydroxyproline, it was not influenced by the dietary protein intake. The contents of Hyl-Gs (μmol/g creatinine) in the first micturition urine after arising and those in the 24-h urine were found to be highly correlated, so it is suggested that the first micturition urine after arising, instead of the 24-h urine, is useful to evaluate the diurnal collagen metabolism.

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