• Proceedings of the Korea Society of Environmental Biology Conference
• /
• 2002.11a
• /
• pp.123-126
• /
• 2002

Pollutants that are persistent, bioaccurnulative, and toxic have been linked to numerous adverse effects in human and animals, PBTs include heavy metals, polychlorinated biphenyls (PCBs), dioxins, polycyclic aromatic compounds (PACs) in addition to pesticides. This study focuses on toxic effects of the PBTs except pesticides on insects. Eight PBTs were selected from subgroups: three heavy metals (Pb, Hg, and Cd), two PCB mixtures (Aroclor mixtures 1 and 2), 2,3,7,8-tetrachlorodibenzo-p-dioxin, two monophenols (4-octylphenol and 4-nonylphenol), and tetrabutyltin, Beet armyworm, Spodoptera exigua, was used as test target insect species. Three physiological markers (metamorphosis, immune reaction, and follicle patency) were assessed in each exposure to different doses of the PCBs. Heat-shock proteins as molecular markers were also analyzed in response to the PCBs. All tested PBTs were toxic to metamorphosis from larvae to pupae when they were applied with diet. Two PCB mixtures were the most toxic compounds in this assay by giving significant toxicity at 0.005 ppm, while others had from 10 to 1000 ppm. Dioxin (0.1 ppb), tetrabutyltin (0.1 ppb), Pb (10 ppb), and Hg (0,01 ppb) were potent to inhibit immune reactions analyzed by inducing phenoloxidase activity and blocked phospholipase $A_2$ enzyme, Tetrabutyltin and dioxin significantly induced follicle cell patency, but their effects were lower than that of endogenous juvenile hormone, Dioxin, Pb, Hg, and Cd could induce the expression of heat shock proteins that were detected by immunoblotting against human HSP70 monoclonal antibody. HSP78 and HSP80 were upregulated in response to the PBTs. This expression was detected from the fat body and epidermis at as fast as 4h after injection. All these results clearly suggest that PBTs give significant ecotoxicity to insects that are valuable organisms in our environment.

• Macromolecular Research
• /
• v.13 no.2
• /
• pp.128-134
• /
• 2005

The phosphorus comonomer [(6-oxido-6H-dibenz<1,2>oxaphosphorin-6-yl)methyl]-methyl butane-dioate (DOP-MBDA) was synthesized through the addition reaction of dimethyl itaconate (DMI) with 9,10-dihydro­9-oxa-10-phosphaphenan threne-10-oxide (DOP). A series of novel flame retardant poly(butylene terephthalate)s (PBTs) containing different amounts of phosphorus were prepared using DOP-MBDA as a comonomer. These novel polymers were characterized by $^{1}H-NMR$, IR, and differential scanning calorimetry (DSC). The novel phosphorus­containing poly(butylene terephthalate)s, referred to as FR-PBTs, exhibited interesting thermal and mechanical behavior, as well as superior flame retardancy. These properties are attributed to the effect of incorporating the rigid structure of DOP-MBDA and the pendant phosphorus group into the poly(butylene terephthalate) (PBT) homopolymer. The UL 94-V2 rating could be achieved with this novel flame retardant PBT, which has a phosphorus content as low as $0.5 wt\%$, and the FR-PBTs emitted less fumes and toxic gases than the PBT homopolymer.

• The Korean Journal of Pesticide Science
• /
• v.13 no.2
• /
• pp.87-97
• /
• 2009

Octachlorostyrene (OCS) is a persistant and bioaccumulative toxic subtance (PBTs). In this study, acute toxicity tests on algae, daphnia and fish for octachlorostyrene and its isomers were done to determine effective concentration ($EC_{50}$), Lethal concentration ($LC_{50}$), no observed effect concentration (NOEC) or lowest observed effect concentration (LOEC). As a result, NOEC on algae growth inhibition test for octacholorostyrene and 2-, 3-chlorostyrene was determined as $0.50\;mg\;L^{-1}$, and NOEC for 4-chlorostyrene was determined as $0.13\;mg\;L^{-1}$. NOEC on daphnia, acute immobilisation test for octachlorostyrene and 2-, 3-chlorostyrene was determined as $5.00\;mg\;L^{-1}$ and $EC_{50}$ for 4-chlorostyrene was determined as $2.128\;mg\;L^{-1}$. NOEC on Oryzias Latipes, acute toxicity test for octachlorostyrene was determined as $80.0\;mg\;L^{-1}$ and NOEC for 2-, 3-chlorostyrene was determined as $60.0\;mg\;L^{-1}$. $LC_{50}$ for 4-chlorostyrene was determined as $39.0\;mg\;L^{-1}$ (48h) and $22.6\;mg\;L^{-1}$ (96h).

• Proceedings of the Korean Society of Applied Entomolohy Conference
• /
• 2002.11a
• /
• pp.129-129
• /
• 2002

• Journal of Environmental Policy
• /
• v.13 no.2
• /
• pp.65-98
• /
• 2014

Plastics of the marine environment are broken gradually down into smaller particles by chemical weathering, called "microplastic". Microplastics absorb organic pollutants that are persistent bioaccumulative substances. If marine animals ingested microplastic added to contaminant, it will lead to a bioaccumation through the food web. It eventually destroy health of marine environment and is harmful to marine top predators including humans. Also, Microplastics can impact marine animals by leaching the endocrine disruptor in microplastic itself as well as playing an adsorbent role of organic pollutants. Persistent and bioaccumulative substances in Korea have been regulated in terms of chemical risk but existing regulations largely have been limited in land-based source management of microplastic. Thus, the harmful impact will be increased whether the microplastics absorbed contaminants. To prevent risk of persistent bioaccumulative substances, this study suggests the following: (1) the strict management of microplastic by designating the hazardous substances, (2) expand the use of biodegradable plastic, (3) the effort for reuse and recycle, (4) the expand of microplastic clean-up programs.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.10 no.4
• /
• pp.201-210
• /
• 2007

Pollution by chemical substances such as POPs, EDCs and PBTs in the ecosystem has become more complex and varied, increasing the possibility of irreversible damage to human health or the ecosystem. It is necessary to have a exposure assessment in a multi-media environment for various chemical substances is required for efficient management. This study applied MUSEM(Multi-media Simplebox-systems Environmental Model), a multimedia environmental model that can simultaneously evaluate the possibility of exposure of hundreds of chemical substances in order to efficiently manage chemical substances that can have negative impact on human health or ecological environment through environmental contamination. MUSEM executed the modeling for Japan by setting all 47 prefectures of japan as the regional area for 62 chemical substances and the rest of the territory of japan, excluding regional area, as the continental area and made the estimation of concentration among environment media in each administrative area and made the sensitivity analysis on Tokyo area. The results of simulation for chemical distribution showed that most of the target chemicals located in water region. The result of sensitivity analysis for octanol-water partition rate showed that the concentration change of soil in urban/industrial area and sediment in freshwater was high. In the case of sensitivity analysis for degradation rate showed that the concentration change of freshwater, soil in urban/industrial area, and sediment in freshwater was high.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.33 no.1
• /
• pp.6-9
• /
• 2020

Thin film transistors (TFTs) with large-area, high mobility, and high reliability are important factors for next-generation displays. In particular, thin transistors based on IGZO oxide semiconductors are being actively researched for this application. In this study, several methods for improving the reliability of a-IGZO TFTs by applying various materials on a passivation layer are investigated. In the literature, inorganic SiO₂, TiO₂, Al₂O₃, ZTSO, and organic CYTOP have been used for passivation. In the case of Al₂O₃, excellent stability is exhibited compared to the non-passivation TFT under the conditions of negative bias illumination stress (NBIS) for 3 wavelengths (R, G, B). When CYTOP passivation, SiO₂ passivation, and non-passivation devices were compared under the same positive bias temperature stress (PBTS), the Vth shifts were 2.8 V, 3.3 V, and 4.5 V, respectively. The Vth shifts of TiO₂ passivation and non-passivation devices under the same NBTS were -2.2 V and -3.8 V, respectively. It is expected that the presented results will form the basis for further research to improve the reliability of a-IGZO TFT.

• Environmental Analysis Health and Toxicology
• /
• v.25 no.1
• /
• pp.41-55
• /
• 2010

The aims of this study were to develop the suitable "system software" in chemical ranking and scoring (CRS) for the food hazardous chemicals associated with environmental emission and to suggest the priority lists of food contamination by environmental-origined pollutants. Study materials were selected with reference to the priority pollutants list for environment and food management from domestic and foreign research and the number of study materials is 103 pollutants (18 heavy metals, 10 PBTs, 10 EDs, and 65 organic compounds). The Food-CRS-Korea system consisted of the environmental fate model via multimedia, transfer environment to food model, and health risk assessment by contaminated food intake. We have established that health risks of excess cancer risks, hazard quotients (HQs) by chronic toxicity and HQs by reproductive toxicity convert to score, respectively. The creditable scoring system was designed to consider uncertainty of quantitative risk assessment based on VOI (Value-Of-Information). The predictability of the Food-CRS-Korea model was evaluated by comparing the presumable values and the measured ones of the environmental media and foodstuffs. The priority lists based on emissions with background-level-correction are 15 pollutants such as arsenic, cadmium, and etc. The priority lists based on environmental monitoring date are 17 pollutants including DEHP, TCDD, and so on. Consequently, we suggested the priority lists of 13 pollutants by considering the several emission and exposure scenarios. According to the Food-CRS-Korea system, arsenics, cadmium, chromes, DEHP, leads, and nickels have high health risk rates and reliable grades.