• Journal of Korean Society of Environmental Engineers
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• v.36 no.12
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• pp.821-827
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• 2014

The 4major river project has caused changes in flow and water quality patterns in major rivers in Korea including the Nakdong River where several toxicant release accidents have had occurred. Three dimensional hydrodynamic model, the Environmental Fluid Dynamics Code (EFDC), was applied to evaluate the effect of geomorphological change of the river on the advection and dispersion patterns of a conservative toxic pollutant. A hypothetical scenario was developed using historical data by assuming a toxic release from an upstream location. If there is a toxic release at the Gumi Industrial Complex, the toxic material would be detected after 2.22 and 9.83 days at Chilgok and Gangjung weir, respectively, in the new river system. It was estimated that they took at least 12 times longer than those with the river conditions before the project. Effect of relocation of intake towers for Daegu Metro City to upstream of Gumi City was also evaluated using the developed modeling system. It was observed that hydraulic residence time would be increased due to decreased flow rate and thus due to lowered water level. However, peak concentration differences were found to be about 2% lower in both places due to increased dispersion effect after the relocation.

• Journal of Environmental Health Sciences
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• v.33 no.2 s.95
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• pp.123-131
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• 2007

Many environmental contaminants including several metals, polycyclic aromatic hydrocarbons, and pharmaceuticals, have been identified to be phototoxic in the water environment. Concerns regarding photo-enhancement of toxicity of several environmental contaminants have been increasing because of the increased level of ultraviolet irradiation on the earth surface. However, there exist arguments that there might be certain defense mechanisms taking place in the aquatic ecosystem, which may include behavioral characteristics or genetic acclimation. This study was conducted to understand the potential responses of aquatic receptors to several phototoxic metals in the real environment, where long-term acclimation of such organisms to low dose UV-B may take place. For this purpose, water flea Daphnia magna was acclimated to environmentally relevant dose of UV-B (12 to $18uW/cm^2$) for >11 generations. The differences in developmental and life history characteristics, and toxicity responses were evaluated. Acclimation did not affect the daphnids' growth, longevity, and reproduction characteristics such as time to first brood, and brood size: After 21 d, survival of D. magna was not influenced by UV-B acclimation. When the number of young per female was compared. the daphnids acclimated for 11 generations tend to produce less number of neonates than the un-acclimated individuals but with no statistical significance (p>0.05). Four metals that were reported to be phototoxic elsewhere were employed in this evaluation, that include As, Cd. Cu, and Ni. UV-B level being applied in acclimation did increase the toxicity of Cd and Cu, significantly (p<0.05). However, the toxicities of As and Ni were not affected by irradiation of UV-B. Phototoxic responses were evaluated between the acclimated and the un-acclimated daphnids. For Cu, UV-B acclimation led to reduction of the photo-induced toxicity $(p\approx0.1)$ in daphnids. Non-acclimated Daphnia were affected by 50% at 4.18 ug/l Cu. but UV-B acclimated individuals exhibited $EC_{50}$ of 5.89 ug/l. With Cd, UV-B acclimation appeared to increase phototoxicity (p>0.05). With As and Ni, UV-B acclimation did not influence photo-induced toxicity. This observation may be in part explained by the type of reactive oxygen species that were generated by each metal. Similar to UV-B light, Cu is known to generate superoxide anion by acting as redox cycling toxicant. This is one of the first studies that employed_laboratory based UV-B acclimated test species for photoenhanced toxicity evaluation.

• Toxicological Research
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• v.18 no.4
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• pp.401-409
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• 2002

Phthalate esters have possible effects on the endocrine system. Di-n-butyl phthalate (DBP) is one of the most commonly wed phthalic acid esters (PAEs). It is extensively wed as a plasticizer in elastomers, as a solvent for printing inks and resins, and as a textile lubricating agent. It is also present in the formulations of various cosmetic products. DBP has been identified as a reproductive toxicant in several animal species and also know as a endocrine disruptor. The objective of this study was to investigate the effect of DBP on developmental immune Junction wing rat pups as experimental animals. Timed-bred pregnant SD rats were orally dosed with 0, 250, 500, or 750 mg DBP/kg body weight once a day from gestational day (GD) 5 to 18 and postpartum day (PD) 3 to 18. On PD22, the dams and their pups were euthanized and examined for alteration in parameters associated to immune function. The results showed no significant changes in body weight, thymus weight, thymus and spleen cellularities, the polyclonal activation respones of splenocyte with ConA and LPS, and also the distribution of arterial blood cells and thymocyto subsets in both rat dam and pups. However DBP exposure on rat dam resulted in increases of liver weights of dam and their pups except 750 mg DBP/kg, and body and spleen weights in pups except 750 mg DBP/kg. On the other hands, distribution rates of CD8+ T cells at 500 mg DBP/kg and B cells at 750 mg DBP/kg among splenocyte subsets were significantly increased in rat pups, unlike dams. Reasons of these distribution alterations of CD8+ T cells and B cells in rat pups are under study.

• Korean Journal of Veterinary Pathology
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• v.1 no.2
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• pp.97-106
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• 1997

This study was carried out to investigate the testicular toxicity of environmental toxicant, 2-bromopropane(2-BP) recently caused occupational intoxication in Korea by light microscopy and electron microscopy. To evaluate the effect on spermatogenesis and find target germ cell 10 weeks old male Sprague-Dawley rats were treated with 5g/10m ℓ/kg/day of 2-bromopropane for 3 consecutive days orally and observed on day 1 or day 7 after treatment. 2-BP induced depletion of spermatogonia and early spermatocytes on stages I-IX or extensive degeneration of germ cells on the other stages on day 1. But extensive degeneration of germ cells without stage specificity was observed and round spermatid formed multinucleated giant cells in the lumen of seminiferous tubules on day 7. Electron microscopically Sertoli cells showed irregular shape of nucleus and cytoplasmic vauolation. And spermatocyte showed a extensive heterochromatin and cytoplasmic vacuolation. But there was no histopathological changes in the interstial cells. On the base of the results the target germ cell was spermatogonia in the early of the study but Srtoli cells also effected by high-dosed 2-BP in the late of the study.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.28-30
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• 2005

Because of high population diversity in soil microbial communities, it is difficult to accurately assess the capability of biodegradation of toxicant by microbes in soil and sediment. Identifying biodegradative microorganisms is an important step in designing and analyzing soil bioremediation. To remove non-important noise information, it is necessary to selectively enrich genomes of biodegradative microorganisms fromnon-biodegradative populations. For this purpose, a stable isotope probing (SIP) technique was applied in selectively harvesting the genomes of biphenyl-utilizing bacteria from soil microbial communities. Since many biphenyl-using microorganisms are responsible for aerobic PCB degradation In soil and sediments, biphenyl-utilizing bacteria were chosen as the target organisms. In soil microcosms, 13C-biphenyl was added as a selective carbon source for biphenyl users, According to $13C-CO_2$ analysis by GC-MS, 13C-biphenyl mineralization was detected after a 7-day of incubation. The heavy portion of DNA(13C-DNA) was separated from the light portion of DNA (12C-DNA) using equilibrium density gradient ultracentrifuge. Bacterial community structure in the 13C-DNAsample was analyzed by t-RFLP (terminal restriction fragment length polymorphism) method. The t-RFLP result demonstates that the use of SIP efficiently and selectively enriched the genomes of biphenyl degrading bacteria from non-degradative microbes. Furthermore, the bacterial diversity of biphenyl degrading populations was small enough for environmental genomes tools (metagenomics and DNA microarrays) to be used to detect functional (biphenyl degradation) genes from soil microbial communities, which may provide a significant progress in assessing microbial capability of PCB bioremediation in soil and groundwater.

• The Korean Journal of Physiology and Pharmacology
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• v.16 no.6
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• pp.469-476
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• 2012

2,3,7,8-Tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) is an environmental toxicant with a polyhalogenated aromatic hydrocarbon structure and is one of the most toxic man-made chemicals. Exposure to 2,3,7,8-TCDD induces reproductive toxicity, immunotoxicity, and hepatotoxicity. In this study, we evaluated how 2,3,7,8-TCDD-induced hepatotoxicity affect the expression of heat shock proteins and antioxidant enzymes using the real-time polymerase chain reaction (PCR) in rat. 2,3,7,8-TCDD increased heat shock protein (Hsp27, ${\alpha}$-B-crystallin, Mortalin, Hsp105, and Hsp90s) and antioxidant enzymes (SOD-3, GST and catalase) expression after a 1 day exposure in livers of rats, whereas heat shock protein (${\alpha}$-B-crystallin, Hsp90, and GRP78) and antioxidant enzymes (SOD-1, SOD-3, catalase, GST, and GPXs) expression decreased on day 2 and then slowly recovered back to control levels on day 8. These results suggest that heat shock proteins and antioxidant enzymes were induced as protective mechanisms against 2,3,7,8-TCDD induced hepatotoxicity, and that prolonged exposure depressed their levels, which recovered to control levels due to reduced 2,3,7,8-TCDD induced hepatotoxicity.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.22 no.3
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• pp.235-243
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• 2012

Objectives: The purpose of this study is the work environment management method through risk assessment and investigation of the work place that deals with Ammonium nitrate, based on information in and outside the country. Methods: This study suggests method of work environment management through risk assessment and investigation of the work place that deals with Ammonium nitrate, and finds out cases of Ammonium nitrate causing hazard, danger and health risk, based on literature investigation. Results: Rats exposed repeatedly to $LD_{50}$ 2,217 mg/kg(rat), $LC_{50}$ 88.8 mg/L(rat, skin) which cause high level of skin irritation, reported 1 $mg/m^3$ of NOAEL, while LOAEL was less than 100 mg/kg for the rats orally administered with the $LD_{50}$ 2,217 mg/kg(rat), $LC_{50}$ 88.8 mg/L(rat, skin), for 13 weeks. Domestically 31,640 ton/y of ammonium nitrate has been used in 22 workplace and the result of workplace assessment was 0.0171-0.9983 $mg/m^3$. ADD was 8.77-59.63 ${\mu}g/kg-day$ according to the exposure scenario. In other words the result of the risk assessment goes beyond the 'standard 1'. Conclusions: Ammonium nitrate creates a high level of irritation and toxicity when coming in breathe it or contact with skin, and is classified as category3 of GHS and specific target organ toxicant (irritating respiratory system). Exposure level at work places needs to be maintained under $1mg/m^3$, to prevent workers from being damaged.

• Environmental Mutagens and Carcinogens
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• v.18 no.2
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• pp.71-76
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• 1998

Exposure to environmental toxicants can cause cellular problems including the interference of DNA repair processes which may lead to the development of cancer. The existence of toxicant-induced DNA repair abnormality was investigated using mice exposed in vivo to genotoxic chemicals and then challenging their exposed lymphocytes in vitro with bleomycin. The repair of bleomycin-induced DNA damage as estimated by the frequency of chromosome aberrations was determined. Our data indicates that the observed aberration frequencies after in vivo exposure to N-methyl-N'-nitro-N-nitnsoguanidine (MNNG) and in vitro challenge with bleomycin are consistently higher than expected. The enhanced response is not due to the induction of chromosome damage by 25 or 50 mg/kg MNNG since the chemical did not cause chromosome aberrations in lymphocytes of these mice. The observed response after the combined exposure to benzo[a]pyrene (BP) and bleomycin was significantly lower than expected with low in vivo doses of BP (50 mg/kg) and then significantly higher than expected with the high doses (200 mg/kg). We interpret our data to indicate that in vivo exposure to genotoxic agents can cause abnormal DNA repair activities. The response is, however, independent of the clastogenic activities of the inducing chemicals, but dependent upon the inducing agents and on the exposure doses.

• Korean Journal of Environmental Agriculture
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• v.14 no.3
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• pp.289-295
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• 1995

This study was carried out to develop a controlled-release insecticide formulation for the control of rose aphid (Macrosiphum ibarae) in rose and cotton aphid (Myzus persicae) in chrysanthemum (Dendranthema grandiflorum var. Meibung) in greenhouse. Imidacloprid[1-(6-chloro-3-pyridylmethyl)-N-nitroimidazolidin-2-ylideneamine] was chosen as a toxicant. Two synthetic polymers, low density polyethylene(LDPE) and ethylene vinyl acetate(EVA), were used as polymer matrices. The tested plastic sheet formulations were prepared by heat-aided extrusion procedures after mixing imidacloprid technical and the polymers of three different combinations, and physicochemical properties as well as efficacy of the formulations were investigated. The amounts of imidacloprid recovered and incorporated in the formulations were recorded over 90% and 80%, respectively. Release of the active ingredient from the formulations was remarkably affected by mixing rates of polymers. The active ingredient in the formulations was chemically unstable with over 10% degradation rates after 90 day storage at $50{\pm}2^{\circ}C$. The residual amounts of imidacloprid in the soil treated with the formulations were paralleled with the release pattern of the formulations. Efficacy of the formulations on rose and cotton aphid was maintained over 90% even 120days after treatment under greenhouse.

• Proceedings of the Korea Environmental Mutagen Society Conference
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• 2002.11a
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• pp.80-88
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• 2002

Recent studies demonstrate that collagen IV selectively pro-motes the repair of physiological processes in sublethally injured renal proximal tubular ceils (RPTC). We sought to further define the mechanisms of cell repair by measuring the effects of toxicant injury and stimulation of repair by L-ascorbic acid-2-phosphate (AscP), exogenous collagen IV, or function-stimulating integrin antibodies on the expression and subcellular localization of collagen-binding integrins (CBI) in RPTC. Expression of CBI subunits ${\alpha}_1$, ${\alpha}_2$, and ${\beta}_1$ in RPTC was not altered on day 1 after sublethal injury by S-(1,2-dichlorovinyl)-L-cysteine (DCVC). On day 6, expression of ${\alpha}_1$ and ${\beta}_1$ subunits remained unchanged, whereas a 2.2-fold increase in ${\alpha}_2$ expression was evident in injured RPTC. CBI localization in control RPTC was limited exclusively to the basal membrane. On day 1 after injury, RPTC exhibited a marked inhibition of active $Na^+$ transport and a loss of cell polarity characterized by a decrease in basal CBI localization and the appearance of CBI on the apical membrane. On day 6 after injury, RPTC still exhibited marked inhibition of active $Na^+$ transport and localization of CBI to the apical membrane. However, DCVC-injured RPTC cultured in pharmacological concentrations of AscP (500 ${\mu}$M)or exogenous collagen IV (50 ${\mu}$g/ml) exhibited an increase inactive $Na^+$ transport, relocalization of CBI to the basal membrane, and the disappearance of CBI from the apical membrane on day 6. Function-stimulating antibodies to CBI ${\beta}_1$ did not promote basal relocalization of CBI despite stimulating the repair of $Na^+$/$K^+$-ATPase activity on day 6 after injury. These data demonstrate that DCVC disrupts integrin localization and that physiological repair stimulated by AscP or collagen IV is associated with the basal relocalization of CBI in DCVC-injured RPTC. These data also suggest that CBI-mediated repair of physiological functions may occur independently of integrin relocalization.