Effect of particle size on risk assessment of direct soil ingestion and metals adhered to children's hands at playgrounds.

The quantity of heavy metals in soil is measured after 2-mm sieving in Japan for risk assessment of direct soil ingestion. A study was conducted on the relationship between the size of soil particles and quantity of heavy metals in soil, and the particle-size distribution of soil adhered to children's hands, and the risks of direct intake of soil considering the particle sizes ingested were evaluated. The results showed that smaller particles had a tendency to contain more heavy metals than bigger ones, that the particle size of approximately 90% of the soil particles from playgrounds adhered to children's hands was less than 100 μm, and that 2-mm sieving in preparation for measuring heavy metal content caused underestimation of the risk of direct soil intake.

Characteristics of biosolids in dimethyl ether dewatering method.

In this study, a method for removing water from biosolids that uses dimethyl ether (DME) as an extractant was considered. This study evaluates the applicability of the DME dewatering method to biosolid cakes by using a DME flow-type experimental apparatus. It was found that a high dewatering ratio is clearly achieved by increasing the liquefied DME/biosolid ratio and lowering the liquefied DME linear velocity.

Methodology for setting risk-based concentrations of contaminants in soil and groundwater and application to a model contaminated site.

In Japan, environmental standards for contaminants in groundwater and in leachate from soil are set with the assumption that they are used for drinking water over a human lifetime. Where there is neither a well nor groundwater used for drinking, the standard is thus too severe. Therefore, remediation based on these standards incurs excessive effort and cost.

The calcination process in a system for washing, calcinating, and converting treated municipal solid waste incinerator fly ash into raw material for the cement industry.

Calcination is the second step in a washing-calcination-conversion system in which treated municipal solid waste incinerator fly ash and bottom ash can be reused as raw material in the cement industry and can decompose or stabilize hazardous compounds, reduce residue amounts, and alter residue characteristics. In this research, only fly ash is discussed. Chloride reduction is important if treated fly ash is to be reused in cement; however, the relationship between washed fly ash properties and chloride reduction by calcination is not well understood.

Deodorization and dewatering of biosolids by using dimethyl ether.

We proposed a method for the deodorising and dewatering of biosolids. In the proposed method, liquefied dimethyl ether (DME) was used as an extractant for odorous components and water. We developed a bench-scale experiment to almost completely deodorize and dewater biosolids by using liquefied DME at room temperature.

Chlorination mechanism of carbon during dioxin formation using Cl-K near-edge X-ray-absorption fine structure.

Many environmental organic chemicals have chloride in their structure. Thus, researching the chlorination mechanism of carbon is of interest. Dioxins are typically concentrated in fly ash collected from the post-combustion zone during the operation of municipal solid waste incinerators.

Chlorides behavior in raw fly ash washing experiments.

Chloride in fly ash from municipal solid waste incinerators (MSWIs) is one of the obstructive substances in recycling fly ash as building materials. As a result, we have to understand the behavior of chlorides in recycling process, such as washing. In this study, we used X-ray absorption near edge structure (XANES) and X-ray diffraction (XRD) to study the chloride behavior in washed residue of raw fly ash (RFA).

Chlorinated aromatic compounds in a thermal process promoted by oxychlorination of ferric chloride.

The relationship between the formation of chlorinated aromatic (aromatic-Cl) compounds and ferric chloride in the solid phase during a thermal process motivated us to study the chemical characteristics of iron in a model solid sample, a mixture of FeCl(3) x 6H(2)O, activated carbon, and boron nitride, with increasing temperature. Fe K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy revealed drastic changes in the chemical form of amorphous iron, consistent with other analytical methods, such as X-ray diffraction using synchrotron radiation (SR-XRD) and Fourier-transform infrared (FT-IR) spectroscopy. Atomic-scale evidence of the chlorination of aromatic carbon was detected by Cl-K X-ray absorption near edge structure (XANES) spectroscopy.

Extraction of PCBs and water from river sediment using liquefied dimethyl ether as an extractant.

We investigated whether polychlorinated biphenyls (PCBs) and water could be simultaneously removed from river sediment by solvent extraction using liquefied dimethyl ether (DME) as the extractant. DME exists in a gaseous state at normal temperature and pressure and can dissolve organic substances and some amount of water; therefore, liquefied DME under moderate pressure (0.6-0.

Benzene risk estimation using radiation equivalent coefficients.

We estimated benzene risk using a novel framework of risk assessment that employed the measurement of radiation dose equivalents to benzene metabolites and a PBPK model. The highest risks for 1 microg/m(3) and 3.2 mg/m(3) life time exposure of benzene estimated with a linear regression were 5.

Chloride Behavior in Washing Experiments of Two Kinds of Municipal Solid Waste Incinerator Fly Ash with Different Alkaline Reagents.

To efficiently reduce and reuse fly ash from incinerators, we suggest trying a new alkaline reagent to neutralize the acid compounds in discharged gas from incinerators and reuse fly ash as the raw material in the cement industry. Normally the washing process includes a pretreatment method to remove chlorides to comply with the strict standards for cement. We examined chloride behavior in washing experiments by X-ray absorption near edge structure (XANES) and X-ray diffraction (XRD) for two kinds of fly ash: (1) fly ash collected in a bag filter with the injection of calcium hydroxide (Ca(OH)) for acid gas removal (CaFA), and (2) fly ash collected in a bag filter with the injection of sodium bicarbonate (NaHCO) for acid gas removal (NaFA).

Development of a physiologically based pharmacokinetic model for bisphenol A in pregnant mice.

Bisphenol A (BPA) is a weakly estrogenic monomer used to produce polymers for food contact and other applications, so there is potential for oral exposure of humans to trace amounts via ingestion. To date, no physiologically based pharmacokinetic (PBPK) model has been located for BPA in pregnant mice with or without fetuses. An estimate by a mathematical model is essential since information on humans is difficult to obtain experimentally.

Development of a new E. coli strain to detect oxidative mutation and its application to the fungicide o-phenylphenol and its metabolites.

Oxidative mutation is mainly induced by reactive oxygen species (ROS), such as the superoxide anion radical (O(2)(-)) and hydrogen peroxide (H(2)O(2)). However, in Escherichia coli (E. coli), ROS are eliminated by enzymes such as superoxide dismutase and catalase, which are coded by sodAB and katEG genes.

A physiologically based pharmacokinetic model for endosulfan in the male Sprague-Dawley rats.

Endosulfan, an organochlorine (OC) insecticide belonging to the cyclodiene group, is one of the most commonly used pesticides to control pests in vegetables, cotton, and fruits. To date, no physiologically based pharmacokinetic (PBPK) model has been located for endosulfan in animal species and humans. The estimation by a mathematical model is essential since information on humans can scarcely be obtained experimentally.

Development of an in vitro blood-brain barrier model to study the effects of endosulfan on the permeability of tight junctions and a comparative study of the cytotoxic effects of endosulfan on rat and human glial and neuronal cell cultures.

Endosulfan, an organochlorine (OC) insecticide that belongs to the cyclodiene group, is one of the most commonly used pesticides to control pests in vegetables, cotton, and fruits. Porcine brain microvascular endothelial cells were used to develop a model to study the effects of endosulfan on the permeability of tight junctions in the blood-brain barrier (BBB). BBB permeability, measured as transendothelial electrical resistance, decreased in a dose- and time-dependent manner when treated with alpha-endosulfan, beta-endosulfan, or endosulfan sulfate.

Toxicokinetics of 14C-endosulfan in male Sprague-Dawley rats following oral administration of single or repeated doses.

Endosulfan (ES), an organochlorine (OC) insecticide that belongs to the cyclodiene group, is one of the most commonly used pesticides to control pests in vegetables, cotton, and fruits. The toxicokinetics of 14C-endosulfan following oral administration of a single dose of 5 mg/kg body weight was investigated in male Sprague-Dawley rats. Three rats were sacrificed 30 min, 1 h, 2 h, 4 h, and 8 h after dosing.

Determination of chemical form of antimony in contaminated soil around a smelter using X-ray absorption fine structure.

Only limited information is available about the behavior of antimony (Sb) in contaminated soils. However, understanding the behavior of Sb in contaminated soils is important, because the toxicity or solubility of this element depends on its chemical state. In this study, we investigated the levels of Sb and the chemical forms of Sb in the soil around a smelter using X-ray absorption fine structure (XAFS) spectra.

Comparison of mutagenic potentials and mutation spectra of benzene metabolites using supF shuttle vectors in human cells.

Benzene is a human leukemogen and the metabolites are thought to be deeply involved in benzene leukemogenesis. In a previous study we reported the molecular analysis of p-benzoquinone (p-BQ) mutagenesis by using a supF shuttle vector plasmid and here we report the mutagenesis of the other metabolites, hydroquinone (HQ) and trans, trans-muconaldehyde (MUC). HQ is a precursor of p-BQ and MUC is produced by a ring-opening metabolic pathway.

The dynamic performances of DDTs in the environment and Japanese exposure to them: a historical perspective after the ban.

The fugacity model for evaluating DDTs dynamic performances in the environment was combined with the dietary exposure evaluation model, including the contribution of imported food, to develop the macroscopic mathematical model relating DDTs in the environment with the health risks of the reference Japanese. The model validity was examined by comparing the simulated DDTs concentrations in environmental media, various kinds of food, and dietary intake with those observed. Numerical simulations were done for the past half and future of one century to evaluate the effect of the DDTs usage prohibition in 1970 in Japan.