• Environmental Analysis Health and Toxicology
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• v.30
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• pp.3.1-3.6
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• 2015

Objectives This study aims to evaluate the size-dependent toxicity of spherical silver nanoparticles (Ag NPs) to an endemic benthic organism, Glyptotendipes tokunagai. Methods Ag nanoparticles of three nominal sizes (50, 100, and 150 nm) capped with polyvinyl pyrrolidone (PVP-Ag NPs) were used. Their physicochemical properties, acute toxicity (48 hours), and bioaccumulation were measured using third instar larvae of G. tokunagai. Results The aggregation and dissolution of PVP-Ag NPs increased with exposure time and concentration, respectively, particularly for 50 nm PVP-Ag NPs. However, the dissolved concentration of Ag ions was not significant compared with the median lethal concentration value for $AgNO_3$ (3.51 mg/L). The acute toxicity of PVP-Ag NPs was highest for the smallest particles (50 nm), whereas bioaccumulation was greatest for the largest particles (150 nm). However, larger PVP-Ag NPs were absorbed and excreted rapidly, resulting in shorter stays in G. tokunagai than the smaller ones. Conclusions The size of PVP-Ag NPs significantly affects their acute toxicity to G. tokunagai. In particular, smaller PVP-Ag NPs have a higher solubility and stay longer in the body of G. tokunagai, resulting in higher toxicity than larger PVP-Ag NPs.

• Bulletin of the Korean Chemical Society
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• v.33 no.2
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• pp.613-619
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• 2012

We applied several machine learning methods for developing QSAR models for prediction of acute toxicity to fathead minnow. The multiple linear regression (MLR) and artificial neural network (ANN) method were applied to predict 96 h $LC_{50}$ (median lethal concentration) of 555 chemical compounds. Molecular descriptors based on 2D chemical structure were calculated by PreADMET program. The recursive partitioning (RP) model was used for grouping of mode of actions as reactive or narcosis, followed by MLR method of chemicals within the same mode of action. The MLR, ANN, and two RP-MLR models possessed correlation coefficients ($R^2$) as 0.553, 0.618, 0.632, and 0.605 on test set, respectively. The consensus model of ANN and two RP-MLR models was used as the best model on training set and showed good predictivity ($R^2$=0.663) on the test set.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1998.11a
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• pp.156-161
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• 1998

As grouting materials for ground improvement, silicate materials such as water glass, silica-sol and so forth are used worldwide. However, they may pollute underground water. In this study, fish poison test(Korean standard industrial code KS M 0111) which estimates toxicity for fish is applied to evaluate the toxic effect by grouting materials. From the test result of the sample made of LW, LC50(Median Lethal Concentration) reaches within 24 hours. In case of the silica-sol, it does not even in 96 hours. Therefore, we can conclude that the sililca-sol grouting method is more free from the danger of underground water pollution. From the result that the mortality of fish under the condition of pH 8.6 is 0% within 96 hours, the groundwater can be saved by controlling pH below 8.6 for the grouting in the field.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2006.04a
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• pp.207-208
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• 2006

Earthworms have been widely used as bioindicators for soil ecotoxicity assessment. Ecotoxicity of methyl tert-butyl ether(MTBE) to terrestrial organisms were evaluated by- earthworm assay. Test earthworm species were Perionyx excavatus and Eisenia andrei. The. toxicity test was performed based on a OECD guideline No. 207 with slight modification. Mortality and abnormal morphology of earthworms exposed to different concentrations of MTBE were measured. Toxic levels of MTBE were determined by measuring the median lethal concentration (LC5O) after 72 hours. The toxicity data was statistically analyzed by Trimmed Spearman-Harbor method. This study showed that, P. excavatus is more sensitive to E. andrei, and that earthworm assay can be a good protocol to evaluate the soils contaminated gasoline components.

• Korean journal of applied entomology
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• v.30 no.4
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• pp.291-293
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• 1991

Inter-regional difference in median lethal concentration of Bacillus thuringiensis diamondback moth was disclosed to be high. Pyungchang strain showed at most 41 times resistance compared to KN-IA strain of which $LC_{50}$ value was 5.5 ppm. and Oksan strain Showed 11 times resistance. The JMC strain, susceptible to pyrethroids, also showed 12 times resistance against B.T., suggesting difference in resistance mechanism between pyrethroid and B.t.

• Korean Journal of Environmental Biology
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• v.28 no.2
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• pp.64-68
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• 2010

The mosquito, Aedes albopictus is important vector of humen phatogen such as dengue fever. And Aedes albopictus has widly distribution in oriental regions. This study was conducted to investigate the biological effects of cooper on the development of the Asian tiger mosquitoes, Aedes albopictus (Skuse). Aedes albopictus was affected with pupation ratios, mortalities, and wing lengths of the 3th and 4th instars by exposure to different concentration $CuCl_2$ (0.0, 2.5, 25.0 and 50.0 ppm) for 24 h and 48 h depending on dose and exposure period. The lowest $LC_{50}$ (median lethal concentration) value of $CuCl_2$ was 18.1 ppm at the 3rd instars for 48 h exposure. The pupation ratio of the larvae exposed at 50.0 ppm for 48 h was 14% which was much lower than those exposed to other treatment groups Changes of adult wing length showed significant decreased by Cu treatment. In conclusion, the most prominent effects of high concentration and longer exposure period were to reduce in the survival and pupation rates of larvae and wing length of Ae. albopictus.

• Ocean Science Journal
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• v.40 no.2
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• pp.61-66
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• 2005

Benthic amphipod, Grandidierella japonica widely inhabits the Korean coastal waters and is developed as a standard test species for sediment toxicity tests. We exposed G. japonica to various pollutants including 4 kinds of inorganic metals (Ag, Cd, Cu and Hg), tributyltin [TBT], ammonia and 7 polycyclic aromatic hydrocarbon (PAH) compounds (acenaphthene, chrysene, fluoranthene, fluorene, naphthalene, phenanthrene and pyrene) to estimate the no observed effect concentration (NOEC) and the median lethal concentration (LC50) of each pollutant during the 96-hour acute exposure. Among all tested pollutants, TBT was most toxic to G. japonica, and Rg was most toxic among inorganic metals. The toxicity of pyrene to G. japonica was greatest among PAH compounds, followed by fluoranthene, phenanathrene, acenaphthene, fluorene and naphthalene. The toxicity of PAH compounds was closely related to their physico-chemical characteristics such as $K_ow$ and water solubility. G. japonica responded adequately to pollutant concentrations and exposure durations, and the sensitivity of G. japonica to various inorganic and organic pollutants was generally comparable to other amphipods used as standard test species in ecotoxicological studies, indicating this species can be applied in the assessment of environments polluted by various harmful substances.

• Journal of Life Science
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• v.7 no.4
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• pp.377-383
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• 1997

The acute toxicity effect of triorganotin of trioganotin on the growth of microalgae and shellfish was investigated through flask culture. The value of 120 hr-LC$_{50}$ that is the median lethal concentration of TBTO on the shellfish (R. philipinarum) was found to be 6 $\mu$g/L. The acute toxicity effect of TBTO on T. suecica was obviously shown even at the concentration of 0.5 $\mu$g/L, and the effect diminished as the initial cell density increased. The effect also diminished less in the experiment done under aeration than in that done under non-aeration. To design a chemostat system for the test of chronic toxicity, the culture of T. suecica was executed in photobioreactor. In batch culture, the profiles of chlorophyII a and D.C.W. showed the growth of T. suecica very well, and the maximum specific growth rate was estimated to be 0.54 d$^{-1}$. with this value, as a dilution rate in contimuous culture, pH was nicely maintained between 7 and 9 when air was supplied with 3% CO$_{2}$. From all results and the natural environment of clam, a novel chemostat system was invented. Through this system, we can observe each independent toxicity effect of TBTO and plankton and combined toxicity effect as well.

• International Journal of Industrial Entomology and Biomaterials
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• v.19 no.2
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• pp.237-241
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• 2009

The objective of our study was the evaluation of pathogenicity of a local strain of Mamestra brassicae nucleopolyhedrovirus-K1 (MabrNPV-K1) derived from a diseased larva of M. brassicae found in Korea. The effect of temperature and larval instar on the pathogenicity and production of MabrNPV-K1 was determined under laboratory conditions. The median lethal concentration ($LC_{50}$) values of MabrNPV-K1 for 3rd instar larvae were $3.7\times10^4$ PIBs/larva at $20^{\circ}C$, $9.9\times10^2$ PIBs/larva at $25^{\circ}C$ and $3.8\times10^2$ PIBs/larva at $30^{\circ}C$, respectively. The $LC_{50}$ for the 4th instar larvae was similar to that for the 3rd instar larvae. However, the pathogenicity to the 3rd instar larvae was higher than that to the 4th instar larvae. The median lethal time ($LT_{50}$) values of MabrNPV-K1 were 11.4 to 5.0 days at $30^{\circ}C$ and 18.3 to 5.5 days at $25^{\circ}C$ for the 3rd instar larvae. The $LT_{50}$ value was lowered as temperature went up to $30^{\circ}C$ and dependent on viral concentration. In production efficiency of MabrNPV-K1 using M. brassicae larvae, the mortality of the 3rd instar larvae was 100% when inoculated with $1.0\times10^5$ PIBs/larva and the yield of MabrNPV-K1 was maximal. Regarding the mortality, yield of polyhedra, inoculation doses and required time, the $1.0\times10^4$PIBs/larva at $30^{\circ}C$ was determined as optimal conditions producing polyhedra efficiently.

• Korean journal of applied entomology
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• v.29 no.3
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• pp.184-189
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• 1990

A nuclear polyhedrosis virus (NPV) of the tobacco cutworm, Spodoptera litura would be a promisible agent for the control of the insect. To develop a viral insecticide using S. litura NPV, effect of spray on soybean leaves, temperature, storage, an sunlight on the pathogenicity of the virus were studies as follows: Median lethal concentration ($LC_{50}$) of the virus sprayed on the leaves against the third and the fifth instar larvae were $1.301\times10^{4 PIBS}/ml$ and $1.087\times10^{5 PIBS}/ml$, respectively. On the concentration of $1.0\times10^{5 PIBS}/ml$, median lethal times ($LT_{50}$) were 7.3 days for the 3rd and 8.9 days for the 5th instar larvae. Stability of S. litura NPV was quickly decreased at the higher temperate than $60^{\circ}C$ and at the longer exposure to the higher temperature. Storage of the virus at $-20^{\circ}C$ was kept higher pathogenicity than $4^{\circ}C$ and $25^{\circ}C$. Viral activity was maintained more than 10 days in the sprayed-under leaves, but decreased at 3 day after spray in th sprayed-on the leaf surface when exposed the virus to sunlight.