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ABSTRACT 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 [...]

ABSTRACT 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 [...]

This article describes the dewatering of sewage sludge using liquefied dimethyl ether (DME), which clarified the effect of sludge type and its particle size. Changes in the heating value of the dewatered sludge were also examined. In addition, the change in dewaterability upon reuse of the liquefied DME was investigated experimentally. Regardless of the nature of the sludge, its dewatering behavior was similar. The amount of dewatered water could be increased by decreasing the diameter of the sludge cake. Complete drying of the sludge cake via DME dewatering resulted in retention of approximately 96% of the heating value (17.7 MJ/kg-sludge) of the original sludge cake dry base (18.4 MJ/kg db). The DME could be recovered after extraction, and reuse experiments showed that liquefied DME dewatering performance was unchanged after five reuses. [ABSTRACT FROM AUTHOR]

In this study, we evaluated the applicability of the dimethyl ether (DME) dewatering method originally developed for high-moisture coal to superabsorbent polymer (SAP) and disposable diapers. It was found that liquefied DME successfully extracts water from SAP and disposable diapers. However, the polypropylene outer film and polyurethane used in diapers tended to dissolve in the liquefied DME and were subsequently released with the water discharged. These compounds are highly viscous, making it difficult to remove them from the drain outlet of the prototype. Therefore, the mechanics of the drain outlet should be considered in future studies. [ABSTRACT FROM AUTHOR]

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 μg/m3 and 3.2 mg/m3 life time exposure of benzene estimated with a linear regression were 5.4 × 10−7 and 1.3 × 10−3, respectively. Even though these estimates were based on in vitro chromosome aberration test data, they were about one-sixth to one-fourteenth that from other studies and represent a fairly good estimate by using radiation equivalent coefficient as an “internal standard.” [ABSTRACT FROM AUTHOR]

The mathematical cancer evaluation model, the Generalized Moolgavkar-Venson-Knudson (G-MVK) model and the two-stage MVK model, were applied to Japanese cancer mortality statistics to examine the applicability of the models for estimating the mortality risk with its year and age dependent variation. First the G-MVK model was simplified with the constant mutation parameters, and was applied to determine the number of stages required for cancer induction for sixteen kinds of cancers and total solid cancer. Then the G-MVK model and the two-stage MVK model were compared in their estimation accuracy, and the latter model was calibrated with the Japanese lung cancer and leukemia statistics. The main results obtained under the limits considered in this study are as follows: (1) the number of stages required for cancer induction was determined by numerical fitting with the cancer statistics. The estimated stage number depended on the kind of cancer, and the mortality depended on age and year, (2) the two-stage MVK model was well calibrated with the statistics and was promising for depicting cancer mortality risk, and (3) the combined (one-stage and two-stage) MVK model was applied to leukemia to show that the hereditary chances of leukemia mortality can be depicted under the assumption that some people were born with an intermediate stem cell. [ABSTRACT FROM AUTHOR]

Endosulfan, an organochiorine (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. The PBPK model was constructed based on the pharmacokinetic data of our experiment following single oral administration of 14C-Endosulfan to male Sprague-Dawley rats. The model was parameterized by using reference physiological parameter values and partition coefficients that were determined in the experiment and optimized by manual adjustment until the best visual fit of the simulations with the experimental data were observed. The model was verified by simulating the disposition of 14C-Endosulfan in vivo after single and multiple oral dosages and comparing simulated results with experimental results. The model was further verified by using experimental data retrieved from the literature. The present model could reasonably predict target tissue dosimetries in rats. Simulation with three- time repeated administration of 14C-Endosulfan and experimental data retrieved from the literature by the constructed model fitted fairly well with the experimental results; thus suggesting that the newly developed PBPK model was developed. Sensitivity analyses were used to determine those input parameters with the greatest influence on endosulfan tissue concentrations. [ABSTRACT FROM AUTHOR]

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 α-endosulfan, β-endosulfan, or endosulfan sulfate. Cytotoxicity testing revealed that the three endosulfans did not cause cell death at concentrations of 10 μM and below. The ratio of the average permeability of the filter-grown endothelial cell monolayer to 14C-endosulfan (Pe) going from the outer to the inner compartments with that going from the inner to the outer compartments was approximately 1:1.2–2.1 after exposure to concentrations of 0.01–10 μM. α-Endosulfan, β-endosulfan, and endosulfan sulfate had cytotoxic effects on rat glial (C6) and neuronal (PC12) cell cultures as well as on human glial (CCF-STTG1) and neuronal (NT2) cell cultures. The effects of α-endosulfan were highly selective, with a wide range of LC50 values found in the different cultures, ranging from 11.2 μM for CCF-STTG1 cells to 48.0 μM for PC12 cells. In contrast, selective neurotoxicity was not so manifest in glial and neuronal cell cultures after exposure to endosulfan sulfate, as LC50 values were in the range of 10.4–21.6 μM. CCF-STTG1 cells were more sensitive to α-endosulfan and endosulfan sulfate, whereas NT2 cells were more sensitive to β-endosulfan. [ABSTRACT FROM AUTHOR]

The risk assessment of bisphenol A (BPA) on the development of offspring of humans is an important issue. There have been some reports on the fate of BPA in rodents, but information on the BPA level in fetal organs essential for the extrapolation to humans is inadequate. In the present study, we investigated the distribution pattern of 14C-BPA-derived radioactivity in fetal tissues following administration of 10 mg/kg 14C-BPA to the pregnant mice. The radioactivity was rapidly transferred through placenta and distributed to all fetal organs including reproductive organs and brains in a similar level. The concentration declined slowly compared with dams. Analysis of metabolites in fetuses showed that a fraction of BPA was unexpectedly large compared to the maternal blood. There was no clear effect of the fetal position in a uterus to influence the radioactivity concentration in whole fetuses. The dose dependence of pharmacokinetics should be recognized to extrapolate the pharmacokinetic result from animal experiments at high doses to humans at low doses. Similar experiments were conducted with an addition of two doses, 1 and 100 mg/kg, respectively. The pharmacokinetics seemed to be linear between 1 and 10 mg/kg, although at 100 mg/kg BPA was absorbed slowly and the radioactivity concentrations in fetuses were much higher than expected based on the linear dose dependence. Repeated doses were administered to pregnant mice since humans are exposed to BPA chronically. Radioactivity level in most of the fetal tissues on repeated administration was higher than single administration. [ABSTRACT FROM AUTHOR]

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. The major results obtained under the limits considered are as follows. The DDTs concentrations in environmental media, various kinds of foods, and the dietary intake showed the steady exponential decrease after the DDTs usage prohibition in 1970. The DDE/DDTs ratio is larger in the higher position in an ecological system, and increased steadily with time. The critical exposure of DDTs occurred through animal product intake until 1960; after 1990 marine product intake caused the most exposure. The estimated DDTs intake was evaluated to be less than the PTDI and RfD. The annual excess cancer induction risk due to the annual dietary intake of DDTs was the largest at the level of (0.5 - 2.0) x 10-6] (1/yr) in the early 1970s. The effect of the DDT usage prohibition on dietary exposure reduction was expected to appear after about 20 years. The life-span excess cancer induction risk was conservatively estimated to be larger than 10-5 (1/lifespan) for the reference Japanese who were born before 1970. The DDTs usage prohibition in 1970 was effective to reduce the life-span cancer risk under the 10-5 level. [ABSTRACT FROM AUTHOR]

Radioactive tritium (3H) generated by the atmospheric nuclear detonation tests has been circulated in the global environment to cause, through various pathways, low-level world-wide contamination of the environment and potential health risks to human beings. In this study, the dynamic performance of tritium in the global environment was modeled considering its transport with foods/feeds imported from all over the world. The mathematical model was examined by comparing the numerically simulated results with the fallout monitoring data. Main results obtained in this study were as follows: (1) The mathematical model developed in this study can reproduce well the global scale tritium circulation and its concentration in food; (2) The excess fatality rate of Japanese by the dietary intake of tritium is estimated to be on the order of 10-8 y-1 at present, which is about two orders of magnitude smaller than that by 90Sr; and (3) About 70% of the Japanese internal radiation dose by tritium is due to drinking water. Farm products, especially imported wheat, are secondly important in the Japanese health risk evaluation; its contribution, however, becomes small if the isotopic exchange effect of tritium is considered. Health Phys. 75(3):259-268; 1998 [ABSTRACT FROM AUTHOR]

Abstract: Efforts have been made to reduce municipal wastewater pollutant discharge and improve river water quality in the Yamato-gawa River basin since 2005, as part of a Social Experiment Programme. The Programme was the first one in Japan to disseminate soft interventions in households, measurements to reduce pollutant discharge, in a large river basin with more than two million population. The soft interventions in households are similar to cleaner production in industrial sector because they are not the wastewater treatment and changing of lifestyles. This paper presents several methods for quantification of the pollutant discharge reduction. Two hypothetical soft intervention combinations were defined, the effects of 16 soft interventions were estimated using their proliferation rates, and estimated pollutant discharge reduction was compared with changes in river water quality during the Programme events. For the first method, environmental accounting housekeeping (EAH) books were applied to estimate a 38–53% reduction in biological oxygen demand (BOD), 26–40% reduction in total nitrogen (TN), and 21–32% reduction in total phosphorus (TP). These estimation results were comparable with the field survey results of approximately 100 person population, which were conducted in the late 1980s. Soft interventions were found to be several times more cost effective than hard interventions, such as development of municipal wastewater treatment and river water purification systems. The BOD discharge reduction effects of soft interventions initiated during Programme events increased from 0.3–2.3% in 2005–2007 to 2.4–4.7% in 2007–2009. The questionnaire surveys found that participants in the Programme events in average newly implemented three or four soft interventions in addition to those already implemented at normal times. [Copyright &y& Elsevier]

Abstract: Ferrous metal production is thought to be a major mercury emission source because it uses large amounts of coal and iron ore, which contain trace amounts of mercury impurities. However, there is limited information about mercury emissions during the production process. In this study, we focused on the coke-oven process, sintering furnace process, and blast furnace process. We measured the mercury concentration in the raw materials, products, and byproducts to estimate the amount of mercury emitted and to investigate the behavior of mercury during the processes. Average mercury concentrations were 30.8 μg kg−1 in 54 samples of iron ore and 59.9 μg kg−1 in 33 samples of coal. The total mercury used for ferrous metal production in Japan was estimated to be 8.45 tons in 2005, with 4.07 tons from iron ore, 3.76 tons from coal, and 0.478 tons from limestone. Emissions from the sintering process accounted for more than 90% of the total emissions, and mercury in the exhaust gas was reduced using an activated coke tower and desulfurization equipment installed downstream of an electrostatic precipitator. When byproduct gas generated from coke-oven and blast furnace processes were included, mercury emissions estimates based on actual measurements were 4.08 tons y−1 (in 2005). Thus, about 50% of the mercury input in ferrous metal production was emitted to the atmosphere. The emission factor was calculated as 0.0488 g Hg ton−1 for crude steel production. The introduction of activated coke tower or desulfurization equipment in sintering furnace facilities would reduce mercury emissions. [Copyright &y& Elsevier]

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. This study used washed residues of three types of fly ash--raw fly ash (RFA) from the boiler or economizer of an incineration system, fly ash collected in a bag filter injected with calcium hydroxide (Ca(OH)2) for acid removal (CaFA), and fly ash collected in a bag filter injected with sodium bicarbonate (NaHCO3) for acid removal (NaFA)--in calcination experiments with varying temperature (400-1100 °C) and atmosphere (100% nitrogen [N2] at 25 mL/min or 10% oxygen [O2] [90% N2] at fluxes of 25, 50, and 75 mL/min). From the perspective of chloride reduction, heating to 1000 °C with 1-hr heating time, 1-hr holding time, and an atmosphere of 10% O2/90% N2 was most suitable for calcination. Under these conditions, chloride levels were reduced by 91, 52, and 96%in washed residues of RFA, CaFA, and NaFA, respectively. Among the washed residues, the weight of the washed residue of NaFA decreased the most. [ABSTRACT FROM AUTHOR]

Abstract: 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 (0.6–0.8MPa) at room temperature can be effectively used to extract PCBs and water from contaminated sediment, and it can be recovered from the extract and reused easily. First, we evaluated the PCB and water extraction characteristics of DME from contaminated sediment. We found that 99% of PCBs and 97% of water were simultaneously extracted from the sediment using liquefied DME at an extraction time of 4320s and a liquefied DME/sediment ratio of 60mLg−1. The extraction rate of PCBs and water was expressed in terms of a pseudo-first-order reaction rate. Second, we estimated the amount of DME that was recovered after extraction. We found that 91–92% of DME could be recovered. In other words, approximately 5–10% of DME was lost during extraction and recovery. It is necessary to optimize this process in order to recover DME efficiently. The extraction efficiency of the recovered DME is similar to that of the pure DME. From the results, we conclude that solvent extraction using liquefied DME is suitable for extracting PCBs and water from contaminated sediment. [Copyright &y& Elsevier]

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)2) for acid gas removal (CaFA), and (2) fly ash collected in a bag filter with the injection of sodium bicarbonate (NaHCO3) for acid gas removal (NaFA). We found that the insoluble chlorides in both CaFA and NaFA combined calcium chloride (CaCl2), with some sodium chloride (NaCl) also possibly combined. Under some conditions, the combined CaCl2 and NaCl were released. In particular, when the liquid/solid ratio was greater than 3 or the washing frequency was doubled, less chlorine, insoluble chlorine, and CaCl2 were left in the residues of NaFA than in the residues of CaFA. As a result, it is desirable to use NaHCO3 as the alkaline reagent instead of Ca(OH)2 in the air pollution control system of incinerators for recycling fly ash as a raw material in the cement industry. [ABSTRACT FROM AUTHOR]

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 5.4 x 10(-7) and 1.3 x 10(-3), respectively. Even though these estimates were based on in vitro chromosome aberration test data, they were about one-sixth to one-fourteenth that from other studies and represent a fairly good estimate by using radiation equivalent coefficient as an "internal standard."

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. 14C-endosulfan radioactivity was detected in all tissues at each time point. In a separate experiment urine and feces were collected for 96 h. The total radioactivity recovered in the excreta for 4 days was 106.8% +/- 26.2%, with fecal elimination the major route of elimination route (94.4% +/- 21.4%). The cumulative excretion in the urine for 4 days was 12.4% +/- 4.8%. Radioactivity 8 h after administration was highest in gastrointestinal (GI) tract tissue (20.28 +/- 16.35 mg ES eq./L) and lowest in muscle (0.18 +/- 0.06 mg ES eq./L). The toxicokinetic parameters obtained from 14C-endosulfan-derived radioactivity in blood were distribution half-life (T1/2 x) = 31 min and terminal elimination half-life (T1/2 y) = 193 h. Blood concentration reached its maximum (Cmax) of 0.36 +/- 0.08 mg ES eq./L 2 h after the oral dose. Endosulfan was rapidly absorbed into the GI tract in rats, with an absorption rate constant (ka) of 3.07 h(-1)., ((c) 2005 Wiley Periodicals, Inc.)

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. The major results obtained under the limits considered are as follows. The DDTs concentrations in environmental media, various kinds of foods, and the dietary intake showed the steady exponential decrease after the DDTs usage prohibition in 1970. The DDE/DDTs ratio is larger in the higher position in an ecological system, and increased steadily with time. The critical exposure of DDTs occurred through animal product intake until 1960; after 1990 marine product intake caused the most exposure. The estimated DDTs intake was evaluated to be less than the PTDI and RfD. The annual excess cancer induction risk due to the annual dietary intake of DDTs was the largest at the level of (0.5 - 2.0) x 10(-6) (1/yr) in the early 1970s. The effect of the DDT usage prohibition on dietary exposure reduction was expected to appear after about 20 years. The life-span excess cancer induction risk was conservatively estimated to be larger than 10(-5) (1/lifespan) for the reference Japanese who were born before 1970. The DDTs usage prohibition in 1970 was effective to reduce the life-span cancer risk under the 10(-5) level.