A review of the literature published on the genotoxicity of soil is presented in this report. Subheadings of the report include outlines of genotoxicity assays that have been used to examine the soil samples and methods commonly used to prepare soil samples for genotoxicity assay, and a review of the genotoxicity of soil. Soil has been grouped according to potential sources of pollution, e.g. industrial activity, agricultural practices and motor vehicles. The possible causes of the genotoxicity of the soil are also mentioned.

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This article reviews studies of overproduction of reactive oxygen species during reductive activation of quinones contained in diesel exhaust particles. The resulting inhibition of nitric oxide synthase activity causing suppression of vasorelaxation by phenanthraquinone, one of the quinone in diesel exhaust particles, is also reviewed.

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Ten species of polycyclic aromatic hydrocarbons (PAHs) in rice were determined. Total PAH levels in unpolished rice ranged from 46 to 77 μg/kg dry weight, which an arithmetic mean value of 58 μg/kg dry weight. Phenanthrene was the most abundant in rice and rice straw. Individual PAH content in unpolished rice was higher than in polished rice. Total PAH contents in unpolished rice was 3-fold in polished rice. PAH concentration ratios for the lighter molecular weights (152-202) to the heavier molecular weights (228-252) in rice and paddy leaf, approximated to 70 : 30. Fluoranthene and pyrene commonly exist in environmental waters. River water and rainwater contained much greater levels of PAHs than groundwater. Fluoranthene was the most abundant and phenanthrene was second most abundant in soil. PAHs in the atmosphere directly contributed to the paddy/rice through atmospheric deposition and PAHs in soil and environmental waters indirectly contributed to the paddy/rice through root uptake and bioconcentration.

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The effects of fish (mackerel pike) broiling on indoor air pollution with polycyclic aromatic hydrocarbons (PAH) were investigated using personal cascade impactors (PCI) sampler and a HPLC spectrofluorometric method. Particles in indoor air were separately collected into 3 classes according to their diameters (10 μm, 2.5-10 μm, and 2.5 μm). Acetonitrile could extract PAH, even from fatty particulates generated during fish broiling. PAH were mostly contained in the smallest class (2.5 μm) particulates. The indoor air was polluted with high levels of PAH during broiling when ventilation was not in operation. The benzo[a]pyrene concentration in the smallest particulates at that time was lower at the center of the room than that at the corner opposite to the cooking stand. The PAH concentrations did not always decrease depending on the straight-line distance from the emission source (cooking table). As a result, fish broiling is one of the most important sources of indoor air pollution in Japanese houses.

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In this study, we performed fractional partition and determination of metals in river water by filtering the sample through a membrane filter with pore size of 0.22 μm immediately after sampling. We considered that the total amount of metal was contained in the nonfiltered sample, and fractional determination was performed separately using atomic absorption spectrometry of the metal in both the filtered and nonfiltered samples. The results showed a different pattern of aluminum distribution compared with other elements.

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Using hard capsules (SR318B) developed as a sustained release diclofenac sodium (DF-Na) preparation for once-daily administration, we investigated the persistence of the analgesic effect after oral administration in the canine urate-induced gonarthritis model. In the control group, injection of 2% urate into the knee joint induced gait disorder due to pain 2 hr after administration and thereafter. Gait disorder peaked 6 hr after urate injection, and gradually recovered after 12 hr. In the treatment group, SR318B at 1.0 mg DF-Na/kg body weight was orally administered 6 hr before urate injection, and the walking score significantly decreased 2 hr after urate injection compared with the control group (p < 0.05). Although the analgesic effect was not observed at the peak of urate-induced pain, the walking score significantly decreased 14, 16, and 18 hr after urate injection compared with the control group (p < 0.05). The plasma diclofenac (DF) concentration peaked 6 hr after SR318B administration, and decreased to about 1/3-1/5 12-18 hr after administration (peak of urate-induced pain), and the plasma level was below the quantification limit in three of five animals 24 hr after administration. DF was detected in the synovial fluid 24 hr after administration in all animals and the concentration was 0.03 ± 0.01 μg/ml (mean ± standard error). The above findings showed that the SR318B exhibits a persistent analgesic effect in a canine urate-induced gonarthritis model. Not only DF in the plasma but also the DF that transferred to the synovial fluid may be involved in this persistent analgesic effect.

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In order to explore the possible role of sulfation in the inactivation of environmental estrogens at gastrointestinal sites and their subsequent removal, we investigated the effects of phenolic environmental estrogens on sulfotransferase (ST) activity. The mouse intestine and a human colon carcinoma cell line, Caco-2, were studied. ST enzymes were found to have a high affinity for diethylstilbestrol (DES) and bisphenol A (BPA), whereas phenol ST (PST) activity was strongly inhibited by nonylphenol and genistein in both mice and humans. Kinetic analysis showed that this inhibition was competitive. These observations suggest that nonylphenol and genistein compounds might inhibit PST activity in the human intestine and that they might escape detoxification by sulfation.

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The inhibitory effect of several plant extracts on the production of verotoxin by enterohemorrhagic Escherichia coli O157 : H7 (EHEC) was investigated. The extracts from four plant species, Limonium californicum (Boiss.) A. Heller, Cupressus lustianica Miller, Salvia urica Epling and Jusiaea peruviana L., were effective on the inhibition for verotoxin production (31.3-125 μg/ml). The inhibition against verotoxin production was observed at a concentration lower than the minimal inhibitory concentration (MIC) of each extract of test plants (1000 μg/ml), indicating that these plant extracts would preferentially prevent the production of verotoxin rather than bactericidal effect on EHEC. These findings suggest that the administration of any appropriate plant extract might prevent the production of verotoxin on EHEC in the human intestines.

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Cadmium is a well-studied environmental toxicant. The neurotoxicity of cadmium is a concern, especially in the developing human brain, because it is thought that cadmium exerts long-term and irreversible effects. In the present study cadmium toxicity using human neuroblastoma NB-1 cells was investigated in relation to gene expression and subsequent neurite extension using cDNA macroarray and image analysis techniques. The neurite outgrowth in NB-1 cells was stimulated significantly by the presence of dibutyryl-cyclicAMP (db-cAMP) and by cadmium chloride at sublethal concentrations. Db-cAMP-stimulated neurite outgrowth was associated with a three-fold increased expression of axonal membrane protein growth-associated protein-43 (GAP-43), but cadmium chloride did not affect GAP-43 expression. Db-cAMP also increased dopamine β-hydroxylase gene expression eight-fold and down-regulated muscle/brain cAMP-dependent protein kinase inhibitor gene expression. However, cadmium chloride had no effect on gene expression except for that of metallothionein II (mtII) gene among 1764 genes analyzed. The results demonstrate that the increased neurite outgrowth with cadmium chloride is not associated with the same gene expression profile of that with db-cAMP.

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The amounts of volatile substances responsible for the malodor of human waste (feces and urine) obtained from the storage tank of a community waste-water treatment plant were determined. Thus far, there has been little systematic research on malodor-causing substances of human waste. These substances were collected using Tenax-TA, and their concentrations were determined by the usual thermal-desorption cold-trap injector/gas chromatography/mass spectrometry (TCT/GC/MS). About 90% of the malodor-causing substances were fatty acids: acetic acid, propionic acid and butyric acid. The proportion of ammonia was 6.5%. Other malodor-causing and minor substances detected were indole, skatole, pyridine, pyrrole, hydrogen sulfide, and methyl mercaptan. In addition, a small amount of paradichlorobenzene used as a deodorizer in household toilets was also recognized.

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The effect of saline cathartics magnesium sulphate, sodium sulphate, and sodium citrate on adsorptive capacity of activated charcoal (AC) was investigated in vitro. Solutions of artesunate alone and artesunate with 7.5 mg/ml cathartics solution were vortex mixed for 30 sec with different quantities of AC, incubated in water bath shaker for 30 min at 37°C and analysed for free artesunate spectrophotometrically at 328 nm. Addition of the cathartics caused a significant increase (p < 0.05) in the adsorption of artesunate to activated charcoal. The descending order of increased adsorption by the cathartics is magnesium sulphate, sodium citrate and sodium sulphate.

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We determined the binding affinities of some chemicals suspected of having endocrine-disrupting effects for androgen and/or estrogen receptors (ADR and ERα) by a non-radioisotope (RI) receptor binding assay. Tributyltin had the highest binding affinity for ADR with an IC₅₀ of 7.6 × 10^-6 M, but no affinity for ERα. Bisphenol A and 4-nonylphenol strongly bound to both ADR (IC₅₀ values of 7.9 × 10^-6 and 1.3 × 10^-5 M, respectively) and ERα (IC₅₀ values of 7.8 × 10^-6 and 7.2 × 10^-7 M, respectively). Octachlorostyrene had affinity for both receptors (IC₅₀ for ADR, 2.7 × 10^-5 M; and for ERα, 7.0 × 10^-5 M). Although 4-octylphenol had a low affinity for ADR, it had a high affinity for ERα (IC₅₀ of 9.8 × 10^-6 M). Di-n-butyl phthalate, dicyclohexyl phthalate, and di(2-ethylhexyl)phthalate had low affinities for both ADR and ERα. The affinity of benzophenone was low for both receptors and n-butylbenzene had no affinity for either. Styrene trimers such as 1a-phenyl-4a-(1'-phenylethyl)tetralin (ST-2), 1a-phenyl-4e-(1'-phenylethyl)tetralin (ST-3), 1e-phenyl-4a-(1'-phenylethyl)tetralin (ST-4), and 1e-phenyl-4e-(1'-phenylethyl)tetralin (ST-5) had relatively high affinities, with IC₅₀ values of 1.2-3.1 × 10^-5 M. Styrene dimers showed lower affinities for ADR than the trimers. Some styrene oligomers have been previously reported to have binding affinities for ERα. These findings suggest that some chemicals possess binding affinities for ADR and ERα. It is necessary to examine the effects of substances on various hormone receptors to elucidate their endocrine-disrupting activities.

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From May 1992 to August 1993, rain water and snow samples taken from the Kanazawa suburbs were analyzed to determined the metal concentration and pH and to clarify the distribution of metals. A negative correlation between the quantity of precipitation and quantity of trace elements was noted for some metal elements, and it is speculated that they originated from soil, sea water, or artificial contamination.

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Intestinal flora plays an important role in the decomposition and fecal excretion of methylmercury. The assumed mechanism is that decomposition of organic mercury (o-Hg) to inorganic mercury (i-Hg) by intestinal flora in cecum decreases the reabsorption of mercury in large intestines. To confirm this hypothesis, we examined the large intestinal mercury absorption in vitro from intestinal contents of methylmercury administered mice. Methylmercury (2 mg Hg/kg) was administered intraperitoneally to adult female mice, and the contents of small intestine (ileum) and cecum were taken out 24 hr after the administration. Ratios of organic mercury to total mercury in small intestinal content and cecal content were 86% and 49%, respectively. Contents fo both samall intestine and cecum were packed into cecum and colon of normal mice, respectively, and were incubated in a medium (Tyrode’s solution) at 37°C for 2 hr. 73% of total mercury (t-Hg) was absorbed from small intestinal content into the cecum and medium after the incubation. On the other hand, only 34% of t-Hg was absorbed from cecal content; most i-Hg remained unabsorbed. However, the absorption rate of t-Hg increased to 57% when the cecal content from antibiotics treated mice was used, because of the high percentage (90%) of o-Hg contained. These results suggest that o-Hg in small intestinal and cecal contents can be reabsorbed by cecum and colon in vivo, and that the decomposition of o-Hg to i-Hg by intestinal flora decreases the intestinal reabsorption rate of t-Hg in methylmercury exposed mice.

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