• Bulletin of the Korean Chemical Society
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• v.18 no.8
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• pp.814-818
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• 1997

The chemical waste treatment, APEG (alkali/polyethylene glycol) process has been shown to be effective for the dechlorination of PCBs in transformer oil. Considerable amount of PCBs, however, still remains in the waste exceeding the 25-50 ppm limit set by regulatory agency. A new thermal regeneration technology has been developed in our laboratory for disposal of hazardous organic wastes. Due to the limited oxidation of carbon surface through the reverse movement of flame front to oxidant flow, this technology was termed counterflow oxidative system (COS). Specially, the oxidant flow in the COS process is a principal parameter which determines the optimum conditions regarding acceptable removal and destruction efficiency of adsorbed organic wastes at minimal carbon loss. The COS process, under optimum conditions, was found to be very effective and the removal and destruction efficiency of 99.99% or better was obtained for residual PCBs in the waste while bulk (≥90%) of carbon was recovered. Any toxic formation of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzo furans (PCDFs) were not detected in the regenerated carbon and impinger traps. The results of surface area measurement showed that the adsorptive property of regenerated carbon is mostly reclaimed during the COS process.

• Bulletin of the Korean Chemical Society
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• v.22 no.2
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• pp.149-153
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• 2001

A new methodology for construction of dihydro-1,4-dioxin skeleton was described. Introduction of thio group at the ${\alpha}-position$ of 8 followed by chlorination gave 11, which was to prevent an enolization as well as to promote the facile nucleophilic substitution reaction of ethylene glycol giving 16 in equilibrium with cyclic ether 19. Removal of thio group of 19 and dehydration in the presence of an acid catalyst gave dihydro-1,4-dioxin 21. In case of electron withdrawing trifluoromethyl group is subsituted in C-2, 18 was converted to the corresponding dihydro-1,4-dioxin 20 by the halogenation of hydroxy followed by treatment of triethylamine.

• Journal of Preventive Medicine and Public Health
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• v.36 no.4
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• pp.303-313
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• 2003

General information is summarized, that is necessary to introduce a scientific assessment of the human health and exposure issue concerning dioxin and dioxin-like compound. Scientific literatures were reviewed to assess the background exposures to the dioxin-like compounds for normal residents. Epidemiologic studies were also reviewed to assess malignant and nonmalignant sweets of dioxins. In 1997, the International Agency for Research on Cancer classified 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) as a human carcinogen, primarily based on occupational cohort studies. The US Environmental Protection Agency made the same decision in it's Draft Dioxin Reassessment. Epidemiologic evidences point to a generalized excess of all cancers, without any pronounced excess at specific sites. Reported non-cancer effects included a range of conditions affecting most systems. Among them, chloracne, elevation in gamma glutamyl transferase(GGT), and alterations in reproductive hormones are related to TCDO, Other adverse outcomes, such as lipid concentrations, diabetes, circulatory and heart diseases, immunologic disorders, neurobehavioral effects, and developmental outcomes require further study before their respective relationships to TCDD can be more definitively assessed.

• Analytical Science and Technology
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• v.15 no.1
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• pp.43-53
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• 2002

The analysis of polychlorodibenzo-p-dioxins (PCDDs) and polychlorodibenzo furans(PCDFs) was performed by using four different gas chromatographic columns (SP-2331, DB-5, DB-17 and DB-DIOXIN). The data reported is pertaining to flue gas, fly ash, ambient air, soil and fish. The difference in quantification of samples according to four columns was observed, it was noted that major difference was observed in the flue gas when compared with soil, fly ash, ambient air and fish. The quantification of the same samples according to four columns it was also found that DB-5 column have the highest concentration whereas SP-2331 column showed the lowest concentration. The quantification of DB-17 column for 1,2,3,6,7,8-HxCDF was found to be twice and three times higher when compared with other columns, whereas the quantification of DB-DIOXIN column for 1,2,3,7,8-PeCDD was also found to be over estimated twice when compared with other columns.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.7
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• pp.1345-1355
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• 2000

The main route of exposure of the human population to polychlorinated dibenzop-dioxins(PCDDs) and polychlorinated dibenzofurans(PCDFs) is through the diet. However in Korea, there are few studies on PCDDs/PCDFs levels in environmental samples and foods. The purpose of this study is to analyze concentration of PCDDs/PCDFs in Korean retail foods and to estimate dietary daily intake of them. 9 samples from animal food and 10 samples from plant food were analysed for PCDDs/PCDFs. Concentrations of PCDDs/PCDFs ranged from 0.02(milk) to 5.39(anchovy)pg/g. TEQ levels appeared in order of fish/shellfish, meat, vegetable, cereal, fruit and milk, and these values ranged from 0.0008 to 0.3153pgTEQ/g. The daily intake of PCDDs/PCDFs via food was calculated to be about 37.7pgTEQ/day and these values are equivalent to 0.75 pgTEQ/kg b.w./day, under consideration of 50kg for body weight. The daily intake of PCDDs/PCDFs via food was lower than that in other countries. From these results, it is important to note that fish/shellfish intake is one of the main sources of PCDDs/PCDFs exposure in Korea.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.2
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• pp.125-131
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• 2009

Reductive dechlorination of polychlorinated dibenzo-p-dioxins (PCDDs) and its toxicity change were predicted by the linear free energy relationship (LFER) model to assess the zero-valent iron (ZVI) and anaerobic dechlorinating bacteria (ADB) as electron donors in PCDDs dechlorination. Reductive dechlorination of PCDDs involves 256 reactions linking 76 congeners with highly variable toxicities, so is challenging to assess the overall effect of this process on the environmental impact of PCDD contamination. The Gibbs free energies of PCDDs in aqueous solution were updated to density functional theory (DFT) calculation level from thermodynamic results of literatures. All of dechlorination kinetics of PCDDs was evaluated from the linear correlation between the experimental dechlorination kinetics of PCDDs and the calculated thermodynamics of PCDDs. As a result, it was predicted that over 100 years would be taken for the complete dechlorination of octachlorinated dibenzo-p-dioxin (OCDD) to non-chlorinated compound (dibenzo-p-dioxin, DD), and the toxic equivalent quantity (TEQ) of PCDDs could increase to 10 times larger from initial TEQ with the dechlorination process. The results imply that the single reductive dechlorination using ZVI or ADB is not suitable for the treatment strategy of PCDDs contaminated soil, sediment and fly ash. This LFER approach is applicable for the prediction of dechlorination process for organohalogen compounds and for the assessment of electron donating system for treatment strategies.

• Analytical Science and Technology
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• v.21 no.6
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• pp.443-458
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• 2008

Brominated flame retardants (BFRs) are chemical compounds that inhibit the combustion of organic materials by scavenging free radicals that would otherwise encourage the spread of flames. These compounds are found in a wide variety of materials including paints, plastics, textiles, furniture and electronics. Mounting evidence, however, suggests that the non-reactive BFRs can easily leach into the environment and pose significant environmental and health concerns. PBDDs/PBDFs are often formed in the process of manufacturing brominated flame retardants and from the combustion of waste products containing flame retardants BFR. Therefore, this paper describes the general characteristics, management status, residual concentration in environments and analytical method.

• Molecular & Cellular Toxicology
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• v.1 no.3
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• pp.157-163
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• 2005

Because of their widespread occurrence and substantial biological activity, halogenated aromatic hydrocarbons are one of the important classes of contaminants in the environment. We have performed comparative molecular field analysis (CoMFA) on structurally diverse ligands of Ah (dioxin) receptor to explore the physico-chemical requirements for binding. All CoMFA models have given $q^{2}$ value of more than 0.5 and $r^{2}$ value of more than 0.83. The predictive ability of the models was validated by an external test set, which gave satisfactory predictive $r^{2}$ values. Best predictions were obtained with CoMFA model of combined modified training set ($q^{2}=0.631,\;r^{2}=0.900$), giving predictive residual value = 0.002 log unit for the test compound. We have suggested a model comprises of four structurally different compounds, which offers a good predictability for various ligands. Our QSAR model is consistent with all previously established QSAR models with less structurally diverse ligands. The implications of the CoMFA/QSAR model presented herein are explored with respect to quantitative hazard identification of potential toxicants.

• Journal of Environmental Health Sciences
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• v.41 no.2
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• pp.116-125
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• 2015

Objective: This study was carried out to use pine needles as a passive air sampler (PAS) for atmospheric polychlorinared dibenzo-p-dioxins/furans (PCDD/Fs). Methods: PCDD/Fs concentrations in ambient air ($C_a$, $pg/m^3$) and deposited pine needles ($C_p$, pg/g dry) were analyzed simultaneously from June 1 to December 31. Air samples were taken using two low volume PUF active air samplers with an overall average air volume of approximately $1,200Sm^3$. Pine needles were collected the end of December near the air sampler. PCDD/Fs was analyzed by HRGC/HRMs. Results: A good correlation was shown ($R^2=0.6357$, p=0.0001) between $C_a$ and $C_p$, but a better correlation ($R^2=0.7372$, p<0.0001) existed between the logarithm of octanol-air partitioning coefficient ($LogK_{oa}$) and Log($C_p/C_a$). The average PCDD/Fs sampling rates from air to pine needles were 0.045($0.018-0.185m^3/day-g\;dry$). Conclusion: It was found that pine needles can be used as PAS for atmospheric PCDD/Fs, and they are especially suitable for long time PAS compared to PUF disk PAS.

• Journal of Environmental Health Sciences
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• v.26 no.3
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• pp.11-17
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• 2000

There are among the most relevant toxic emissions from incinerators such as polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), dioxin-like polychlorinated biphenyls (PCBs). Induction of cytochrome P4501A1 catalyzed 7-ethoxyresorufin O-deethylase(EROD) activity in mammalian cell culture(EROD bioassay) is thought to be a selective and sensitive parameter used for the quantification of dioxin-like components. In this study, the toxic emissions from several school waste incinerators were evaluated by determination of CYPIA catalytic activity and cytotoxicity using cell culture microbioassay. The incinerator residue and soil samples were collected from the schools located in Kyunggi province from April to June 1999. The samples were extracted in a Soxhlet apparatus using toluene for 20 hours. In order to clean-up, concentrated crude extracts were applied to basic alumina column. The EROD activities of extracts in the H4IIE cells were from 1.91$\pm$0.32 ng-TEQ/g to 24.54$\pm$3.48 ng-TEQ/g of biochemical-TEQ value. In soil samples, CYP1A catalytic activity was 0.09~0.64 ng-TEQ/g. EROD bioassay, seems to be a useful short-term bioassay when information about the biological response of complex environmental samples is needed. Although further study is needed, these results indicate that the potent toxic emissions are produced from school waste semi-incinerators.