Biomedical subjects

Shinichi Sakai

Publications and source records attributed to Shinichi Sakai.

4 recordsLinked to original sources

PubMed2005

Chemical characterization of polychlorinated biphenyls, -dibenzo-p-dioxins, and -dibenzofurans in technical Kanechlor PCB formulations in Japan.

Technical polychlorinated biphenyl (PCB) formulations-Kanechlor KC-200, KC-300, KC-400, KC-500, KC-600 and KC-1000-produced in Japan were analyzed for the chemical characterization of PCBs, -dibenzo-p-dioxins (PCDDs), and -dibenzofurans (PCDFs) using high-resolution gas chromatography-high-resolution mass spectrometry (HRGC-HRMS) by isotope dilution technique. The homologue/congener profiles of Kanechlor formulations resembled those of Clophen, Aroclor, and Delor, respectively, from Germany, the United States, and Czechoslovakia. Twenty-seven major PCB congeners contributed 50% (in KC-200) to 69-71% (in KC-600, 1000, and 500) to total PCBs. Average total PCB concentrations were 510,000, 800,000, 830,000, 840,000, 870,000, and 880,000 mug/g in KC-1000 (51%), KC-200 (80%), KC-500 (83%), KC-400 (84%), KC-300 (87%), and KC-600 (88%), respectively. Kanechlors also contained PCDDs and PCDFs (4.3 to 0.35 microg/g) as impurities which were approximately 1/10,000 to the PCB concentrations. Congener characterization and concentrations of PCBs and PCDFs were considerably varied in between Kanechlor formulations. The potential for the emissions of PCDDs and PCDFs from Kanechlor was estimated to be 1.94 kg and 464.4 kg, respectively. The average WHO-toxic equivalent (TEQ) was 16 (KC-500) >12 (KC-400) >10 (KC-1000) >4.1 (KC-600) >3.5 (KC-300) >1.9 (KC-200) on microgTEQ/g. Non- and mono-ortho PCBs were the major contributors to the total TEQ in Kanechlor formulations, whereas the PCDD/DF contribution was <2.0%. The environmental input of TEQs from Kanechlors can be estimated to be between 112 and 941 kg.

Benzofurans↗

PubMed2005

Method for the elucidation of the elemental composition of low molecular mass chemicals using exact masses of product ions and neutral losses: application to environmental chemicals measured by liquid chromatography with hybrid quadrupole/time-of-flight mass spectrometry.

A method for elucidating the elemental compositions of low molecular weight chemicals, based primarily on mass measurements made using liquid chromatography (LC) with time-of-flight mass spectrometry (TOFMS) and quadrupole/time-of-flight mass spectrometry (LC/QTOFMS), was developed and tested for 113 chemicals of environmental interest with molecular masses up to approximately 400 Da. As the algorithm incorporating the method is not affected by differences in the instrument used, or by the ionization method and other ionization conditions, the method is useful not only for LC/TOFMS, but also for all kinds of mass spectra measured with higher accuracy and precision (uncertainties of a few mDa) employing all ionization methods and on-line separation techniques. The method involves calculating candidate compositions for intact ionized molecules (ionized forms of the sample molecule that have lost or gained no more than a proton, i.e., [M+H](+) or [M-H](-)) as well as for fragment ions and corresponding neutral losses, and eliminating those atomic compositions for the molecules that are inconsistent with the corresponding candidate compositions of fragment ions and neutral losses. Candidate compositions were calculated for the measured masses of the intact ionized molecules and of the fragment ions and corresponding neutral losses, using mass uncertainties of 2 and 5 mDa, respectively. Compositions proposed for the ionized molecule that did not correspond to the sum of the compositions of a candidate fragment ion and its corresponding neutral loss were discarded. One, 2-5, 6-10, 11-20, and >20 candidate compositions were found for 65%, 39%, 1%, 1%, and 0%, respectively, for the 124 ionized molecules formed from the 113 chemicals tested (both positive and negative ions were obtained from 11 of the chemicals). However, no candidate composition was found for 2% of the test cases (i.e., 3 chemicals), for each of which the measured mass of one of the product ions was in error by 5-6.7 mDa.

Chromatography, Liquid↗

PubMed2003

Open dumping site in Asian developing countries: a potential source of polychlorinated dibenz-p-dioxins and polychlorinated dibenzofurans.

Open landfill dumping areas for municipal wastes in Asian developing countries have recently received particular attention with regard to environmental pollution problems. Because of the uncontrolled burning of solid wastes, elevated contamination by various toxic chemicals including dioxins and related compounds in these dumping sites has been anticipated. In this study, concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and coplanar polychlorinated biphenyls (PCBs) were determined in soils from dumping sites in the Philippines, Cambodia, India, and Vietnam. Residue concentrations of PCDD/Fs and coplanar PCBs in dumping site soils were apparently greater than those in soils collected in agricultural or urban areas far from dumping sites, suggesting that dumping sites are potential sources of PCDD/Fs and related compounds. Observed PCDD/F concentrations in soils from dumping sites in the Philippines and Cambodia were comparable or higher than those reported for dioxin-contaminated locations in the world (e.g., near the municipal waste incinerators and open landfill dumping sites). Homologue profiles of PCDD/Fs in dumping site soils from the Philippines and, to a lesser extent, from Cambodia and India reflected patterns of samples representing typical emissions, while profiles of agricultural or urban soils were similar to those of typical environmental sinks. This result suggests recent formation of PCDD/Fs in dumping site areas and that open dumping sites are a potential source of dioxins in Asian developing countries. Uncontrolled combustions of solid wastes by waste pickers, generation of methane gas, and low-temperature burning can be major factors for the formation of dioxins in dumping sites. Elevated fluxes of PCDD/Fs to soils in dumping sites were encountered in the Philippines, Cambodia, India, and Vietnam-Hanoi, and these levels were higher than those reported for other countries. Considerable loading rates of PCDD/Fs in the dumping sites of these countries were observed, ranging from 20 to 3900 mg/yr (0.12-35 mg TEQ/yr). PCDD/F concentrations in some soil samples from the Philippines, Cambodia, India, and Vietnam-Hanoi exceeded environmental guideline values, suggesting potential health effects on humans and wildlife living near these dumping sites. The estimated intakes of dioxins via soil ingestion and dermal exposure for children were higher than those for adults, suggesting greater risk of dioxin exposure for children in dumping sites. To our knowledge, this is the first comprehensive study on PCDD/Fs contamination in open dumping sites of Asian developing countries. On the basis of the result of this study, we have addressed a new environmental issue that open dumping sites are potential sources of PCDD/Fs and related compounds, and dioxin contamination in dumping sites may become a key environmental problem in developing countries.

Administration, Cutaneous↗

PubMed2002

Prediction of physico-chemical properties for PCs/DFs using the UNIFAC model with an alternative approximation for group assignment.

The original-type UNIFAC model was used to predict the environmentally important physico-chemical properties of PCDDs/DFs, such as aqueous solubility, Henry's law constant, and 1-octanol/water partition coefficient, through the UNIFAC-derived infinite dilution activity coefficient. In this application, we suggest an alternative approximation that the aromatic ether group AC-O in PCDD/DF molecules is replaced with the aliphatic ether group CH-O, because the AC-O group is not available in the conventional UNIFAC model. With this approximation, the ability of the UNIFAC model to predict those properties was examined by comparing with experimental data. The UNIFAC model provided comparatively good estimation results. From these results, it is shown that the alternative approximation is useful for the UNIFAC estimation of physico-chemical properties for PCDDs/DFs. Furthermore, the predicted solubilities of 2,3,7,8-T4CDD and O8CDD in organic solvents and the co-solvency effect on solubility of PCDDs in methanol/water mixture indicate that the UNIFAC calculation presented here could well predict the physico-chemical properties of PCDDs/DFs in various solution conditions.

Benzofurans↗