Urinary concentrations of organophosphorus insecticide metabolites in Japanese workers

A recent development in analytical chemistry has enabled us to monitor systemic organophosphorus insecticide (OP) exposure at individual levels. At present, however, limited data are currently available on urinary OP metabolite levels worldwide. The purpose of this study was to assess urinary dialkylphosphate (DAP) concentrations in Japanese workers. Urine samples were collected in both summer and winter from 339 Japanese adults who worked as food distributors (FDs, n = 164), apple farmers (AFs, n = 147) and pest control operators (PCOs, n = 28). DAPs were measured by gas chromatography-mass spectrometry after derivatization with pentafluorobenzylbromide. Dimethylphosphate (DMP), diethylphosphate (DEP), dimethylthiophosphate (DMTP) and diethylthiophosphate (DETP) were detected in the urine of over 87% of the studied populations in both seasons. The geometric mean values of total DAPs (nmol g⁻¹ creatinine), DMP, DMTP, DEP and DETP (μg g⁻¹ creatinine) in summer and winter were 106.7 and 98.3, 7.0 and 3.8, 3.4 and 4.5, 0.8 and 1.5, and 0.3 and 0.2 for the FDs, 440.8 and 197.7, 33.1 and 10.8, 10.1 and 5.8, 4.2 and 4.7 and 1.6 and 0.8 for the AFs, and 473.4 and 284.6, 28.9 and 22.2, 17.6 and 4.6, 3.5 and 4.4, and 0.5 and 0.6 for the PCOs, respectively, thereby revealing significantly higher concentrations in AFs and PCOs groups than in the FDs in both seasons except for winter DMTP. These DAP concentrations were approximately the same or at lower levels compared with those reported in the previous literature. This is one of the first studies to demonstrate urinary DAP concentrations in Japanese adults.     

Biomass Carbon Ratio of Polymer Composites Measured by Accelerator Mass Spectrometry

The evaluation method of biomass carbon ratio of polymer composite samples including organic and inorganic carbons individually was investigated. Biodegradable plastics and biobased plastics can have their mechanical properties improved by combining with inorganic fillers. Polymer composites consisting of biodegradable plastics and carbonate were prepared by two different methods. Poly(lactic acid) (PLA) composite was prepared by synthesis from l-lactide with catalyst and calcium carbonate (CaCO₃) powders from lime. Poly(butylene succinate) (PBS) composite was prepared by hot-pressing the mixture of PBS powder and CaCO₃ powders from oyster shells. The mechanical properties of composite samples were investigated by a tensile test and a compression test using an Instron type mechanical tester. Tensile test with a dumbbell shape specimen was performed for PBS composite samples and compression test with a column shape specimen for PLA composite samples. Strength, elastic modulus and fracture strain were obtained from the above tests. Biomass carbon ratio is regulated in the American Standards for Testing and Materials (ASTM). In ASTM standards on biomass carbon ratio, it is required that carbon atoms from carbonates, such as CaCO₃, are omitted. Biomass carbon ratio was evaluated by ratio of ¹⁴C to ¹²C in the samples using Accelerator Mass Spectrometry (AMS). The effect of pretreatment, such as oxidation temperature and reaction by acid, on results of biomass carbon ratio was investigated. Mechanical properties decrease with increasing CaCO₃ content. The possibility of an evaluation method of biomass carbon ratio of materials including organic and inorganic carbons was shown.     

Measurements of aerosol optical properties in central Tokyo during summertime using cavity ring-down spectroscopy: Comparison with conventional techniques

A highly sensitive cavity ring-down spectrometer (CRDS) was used to monitor the aerosol extinction coefficient at 532 nm. The performance of the spectrometer was evaluated using measurements of nearly monodisperse polystyrene particles with diameters between 150 and 500 nm. By comparing the observed results with those determined using Mie theory, the accuracy of the CRDS instrument was determined to be >97%, while the upper limit for the precision of the instrument was estimated to be 0.6–3.5% (typically 2%), depending on the particle number concentration, which was in the range of 30–2300 particles cm^?3. Simultaneous measurements of the extinction (b_ext), scattering (b_sca) and absorption (b_abs) coefficients of ambient aerosols were performed in central Tokyo from 14 August to 2 September 2007 using the CRDS instrument, two nephelometers and a particle/soot absorption photometer (PSAP), respectively. The value of b_ext measured using the CRDS instrument was compared with the sum of the b_sca and b_abs values measured with a nephelometer and a PSAP, respectively. Good agreement between the b_ext and b_sca + b_abs values was obtained except for data on days when high ozone mixing ratios (>130 ppbv) were observed. During the high-O₃ days, the values for b_sca + b_abs were ～7% larger than the value for b_ext, possibly because the value for b_abs measured by the PSAP was overestimated due to interference from coexisting non-absorbing aerosols such as secondary organic aerosols.     

Estimating the amount of WEEE generated in South Korea by using the population balance model

We estimated the amount of waste electrical and electronic equipment (WEEE) generated in South Korea by using the population balance model (PBM) based on a lifespan distribution analysis. This is the first study to apply PBM to estimate WEEE generation in South Korea. The lifespan distribution analysis of electrical and electronic equipment (EEE) was based on the results of a questionnaire survey of 1000 households, which were analyzed with the Weibull distribution. As a result, we could estimate the domestic service lifespan and lifespan distribution shape parameter for eight selected products. Using the lifespan distribution analysis and other data, such as the shipment volume and the number of products owned by households, we estimated the amount of WEEE generated for the eight selected items from 2000 to 2020. We found that 1.2 million air conditioners, 2.5 million televisions, 1.3 million microwave ovens, 1.2 million kimchi refrigerators, 17.0 million mobile phones, 1.7 million refrigerators, 2.0 million vacuum cleaners, and 1.4 million washing machines were generated as WEEE in 2010. We also compared our WEEE estimates with the number of items collected through the official WEEE recycling program from 2003 to 2009 and found that in 2009 washing machines had the highest collection rate (28%) and air conditioners had the lowest rate (7%).     

Polychlorinated biphenyl (118) activates osteoclasts and induces bone resorption in goldfish

To analyze the effect of polychlorinated biphenyl (PCB) 118 on fish bone metabolism, we examined osteoclastic and osteoblastic activities, as well as plasma calcium levels, in the scales of PCB (118)-injected goldfish. In addition, effect of PCB (118) on osteoclasts and osteoblasts was investigated in vitro. Immature goldfish, in which the endogenous effects of sex steroids are negligible, were used. PCB (118) was solubilized in dimethyl sulfoxide at a concentration of 10 ppm. At 1 and 2 days after PCB (118) injection (100 ng/g body weight), both osteoclastic and osteoblastic activities, and plasma calcium levels were measured. In an in vitro study, then, both osteoclastic and osteoblastic activities as well as each marker mRNA expression were examined. At 2 days, scale osteoclastic activity in PCB (118)-injected goldfish increased significantly, while osteoblastic activity did not change significantly. Corresponding to osteoclastic activity, plasma calcium levels increased significantly at 2 days after PCB (118) administration. Osteoclastic activation also occurred in the marker enzyme activities and mRNA expressions in vitro. Thus, we conclude that PCB (118) disrupts bone metabolism in goldfish both in vivo and in vitro experiments.     

Phosphate removal and recovery with a synthetic hydrotalcite as an adsorbent

Phosphate removal is important to control eutrophication and an ion exchange process is one of several treatment processes for this purpose. Hydrotalcite compounds (HTALs) are useful as adsorbents for phosphate removal because of their ion exchange properties. In this study, the adsorption properties of a granular synthetic HTAL for phosphate and the method of regeneration of the granular HTAL were examined. The adsorption isotherm of the granular HTAL was approximated by a modified Langmuir type, and the maximum adsorption capacity was 47.3 mg P g(-1), which corresponded to the content of HTAL in the granular one. Phosphate adsorbed on the HTAL was effectively desorbed with alkaline NaCl solutions and the HTAL was regenerated with 25 w/v% MgCl(2) solution. The regenerated HTAL could be reused repeatedly for the phosphate removal. Phosphate in the exhausted desorption solution was recovered as a precipitate of calcium phosphate by addition of CaCl(2), and the residual exhausted desorption solution could be also reused after supplying NaOH. The results suggest the possibility of an effective system for phosphate removal and recovery, which includes the following processes: adsorption, desorption, recovery of phosphate, and regeneration of the HTAL and the desorption solution.     

Fundamental characteristics of input waste of small MSW incinerators in Korea

Waste incineration in a small incinerator is a simple and convenient way of treating waste discharged from small areas or from large facilities and buildings such as business centers, marketplaces, factories, and military units. Despite their ostensible advantages, however, many small incinerators frequently suffer from serious problems, e.g., unsystematic waste feeding, unstable combustion, deficient air pollution control devices, and consequently, environmental pollution. To obtain a better understanding of the characterization of wastes in small incinerators, we investigated a series of fundamental characteristics, i.e., physical composition, bulk density, proximate and ultimate analysis, potential energy content, and so on. The main waste components in small incinerators were identified as paper and plastic; the proportion of food waste was less than that in large incinerators. Especially, a low ratio of food waste had a strong influence on other waste characteristics, e.g., lower moisture content and bulk density, and higher potential energy. On the other hand, in contrast with that of HCl, there was no distinguishable linear relationship between Cl content in waste and PCDD/DF concentration in combustion gas.     

Extraction and cleanup methods of dioxins in house dust from two cities in Japan using accelerated solvent extraction and a disposable multi-layer silica-gel cartridge

A simple and rapid method for the extraction and cleanup of dioxins from house dust was developed using an accelerated solvent extraction (ASE) method and a multi-layer silica-gel cartridge. It was found that the WHO-TEQ levels of dioxins extracted from the house dust obtained by both a conventional soxhlet extraction and the ASE were almost equal, when the data obtained by both methods were compared. As for the cleanup method, a multi-layer silica-gel cartridge yielded higher dioxin recoveries than the alkaline digestion method. The average values of the dioxins in house dust from Kumagaya city and Sendai city in Japan (Sendai city is bigger than Kumagaya city with respect to the population and industry), were 15.6 pg TEQ/g (8.6-26.0 pg TEQ/g, n=5, Kumagaya city) and 16.0 pg TEQ/g (5.9-30.5 pg TEQ/g, n=5, Sendai city), respectively.     

A GIS-based zoning of illegal dumping potential for efficient surveillance

To assist in the efficient surveillance against illegal dumping, this study examined and evaluated two methods to illustrate the illegal dumping potential of sites using GIS (Geographic Information System) data. One approach focused on the occurrence of illegal dumping sites; the other on the size of the illegal dumping. Both approaches to zoning were implemented for the Kanto region of Japan, utilizing seven or eight major geographical attributes most closely related to illegal dumping. The zoning results revealed the areas requiring patrols against illegal dumping. Evaluation of the zoning results using the ROC (Receiver Operating Characteristic) curve showed the number of illegal dumping sites detectable under certain surveillance conditions and that the size-based zoning was superior, but this superiority was insignificant for revealing sites with higher potential for large illegal dumping, for which it would be sufficient to use the occurrence-based zoning. The evaluation also showed the contribution of each geographical attribute. Finally, application of the ROC curve to the surveillance planning process was examined, which enables the total social cost of pollution by illegal dumping, rehabilitation of dumping sites, and illegal dumping surveillance to be minimized.