• Composites Research
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• v.21 no.6
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• pp.8-14
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• 2008

Lighting system of road is an essential structure used for the safety of pedestrians and vehicles. Most of the lighting pole is made with steel which is vulnerable under corrosive environment. To overcome such corrosion problems, stainless steel and iron steel are used, but they are usually manufactured by hand which is not efficient. Due to their high strength and stiffness, when there is car collision with the lighting pole structure the safety of driver may not be ensured. Hence, the development of new-type lighting pole system which is easy to adjust the right on the road, lengthen the service life, and reduce the maintenance, is necessary. Lighting pole made with aluminum alloy is high in strength per unit weight, is strong against corrosive environment, and is easy to construct due to flexibility and right weight. But, because the strength and stiffness of the material is lower than that of steel, the structural safety and serviceability of the system can be a problem. To mitigate the structural problem associated with conventional lighting pole system, experimental investigation is conducted on the conventional lighting pole and rib reinforced aluminum alloy lighting pole, respectively. By comparison of results, it was found that the rib reinforced Mg-Si aluminum alloy lighting pole is efficiently applicable to the lighting pole system of road.

• Toxicological Research
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• v.33 no.1
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• pp.7-14
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• 2017

Didecyldimethylammonium chloride (DDAC) is used in many types of biocidal products including tableware, carpets, humidifiers, and swimming pools, etc. In spite of increased chances of DDAC exposure through inhalation, studies on the inhalation toxicity of DDAC are not common even though the toxicity of DDAC might be significantly higher if it were to be administered through routes other than the respiratory system. DDAC aerosols were exposed to Sprague-Dawley rats in whole body exposure chambers for a duration of 13 weeks. The Mass Median Aerodynamic Diameters of the DDAC aerosol were $0.63{\mu}m$, $0.81{\mu}m$, and $1.65{\mu}m$, and the geometric standard deviations were 1.62, 1.65, and 1.65 in the low ($0.11{\pm}0.06mg/m^3$), the middle ($0.36{\pm}0.20mg/m^3$) and the high ($1.41{\pm}0.71mg/m^3$) exposure groups, respectively. Body weight was confirmed to be clearly influenced by exposure to DDAC and mean body weight was approximately 35% lower in the high ($1.41{\pm}0.71mg/m^3$) male group and 15% lower in the high ($1.41{\pm}0.71mg/m^3$) female group compared to that of the control group. In the bronchoalveolar lavage fluid assay, the levels of albumin and lactate dehydrogenase had no effect on DDAC exposure. The lung weight increased for the middle ($0.36{\pm}0.20mg/m^3$) and the high ($1.41{\pm}0.71mg/m^3$) concentrations of the DDAC exposure group, and inflammatory cell infiltration and interstitial pneumonia were partially observed in the lungs of the middle ($0.36{\pm}0.20mg/m^3$) and the high ($1.41{\pm}0.71mg/m^3$) exposure groups. However, severe histopathological symptoms, including proteinosis and/or fibrosis, were not found. Based on the results of the changes in the body weight and lung weight, it is considered that the NOAEL (no-observed adverse effect) level for the 13-week exposure duration is $0.11mg/m^3$.

• Safety and Health at Work
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• v.3 no.3
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• pp.224-234
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• 2012

Objectives: This study was conducted in order to obtain information concerning the health hazards that may result from a 13 week inhalation exposure of n-pentane in Sprague-Dawley rats. Methods: This study was conducted in accordance with the Organization for Economic Co-operation and Development (OECD) guidelines for the testing of chemicals No. 413 'Subchronic inhalation toxicity: 90-day study (as revised in 2009)'. The rats were divided into 4 groups (10 male and 10 female rats in each group), and were exposed to 0, 340, 1,530, and 6,885 ppm n-pentane in each exposure chamber for 6 hour/day, 5 days/week, for 13 weeks. All of the rats were sacrificed at the end of the treatment period. During the test period, clinical signs, mortality, body weights, food consumption, ophthalmoscopy, locomotion activity, urinalysis, hematology, serum biochemistry, gross findings, organ weights, and histopathology were assessed. Results: During the period of testing, there were no treatment related effects on the clinical findings, body weight, food consumption, ophthalmoscopy, urinalysis, hematology, serum biochemistry, gross findings, relative organ weight, and histopathological findings. Conclusion: The no-observable-adverse-effect level (NOAEL) of n-pentane is evaluated as being more than 6,885 ppm (20.3 mg/L) in both male and female rats. n-pentane was not a classified specific target organ toxicity in the globally harmonized classification system (GHS).

• Journal of Food Hygiene and Safety
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• v.34 no.1
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• pp.13-21
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• 2019

A method was developed for the simultaneous detection of an antibiotic fungicide, streptomycin, and its metabolite (dihydrostreptomycin) in agricultural products using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The samples were extracted using methanol adjusted to pH 3 using formic acid, and purified with a HLB (Hydrophilic lipophilic balance) cartridge. The matrix-matched calibration curves were constructed using seven concentration levels, from 0.001 to 0.1 mg/kg, and linearity of five agricultural products (hulled rice, potato, soybean, mandarin, green pepper), with coefficients of determination $(R^2){\geq}0.9906$, for streptomycin and dihydrostreptomycin. The mean recoveries at three fortification levels (LOQ, $LOQ{\times}10$, $LOQ{\times}50$, n = 5) were from 72.0~116.5% and from 72.1~116.0%, and relative standard deviations were less than 12.3% and 12.5%, respectively. The limits of quantification (LOQ) were 0.01 mg/kg, which are satisfactory for quantification levels corresponding with the Positive List System. All optimized results satisfied the criteria ranges requested in the Codex guidelines and the Food Safety Evaluation Department guidelines. The present study could serve as a reference for the establishment of maximum residue limits and be used as basic data for detection of streptomycin and dihydrostreptomycin in food.

• Membrane Journal
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• v.19 no.4
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• pp.333-340
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• 2009

This paper is designed with the purpose of improving the efficiency of the sulfonic acid ion exchange membranes by radiation induced graft polymerization. It has been shown that the porous hollow fiber membranes could cause permeability blocking between pores and ion exchanged graft chains. Addition of crosslinker such as N-ethylene glycol dimethacrylate will permit to increase the permeation flux. In this research, the ethylene glycol dimethacrylate (EDMA) and diethylene glycol dimethacrylate (DDMA) with different length are used as crosslinkers. The ion exchanged cross-linked membrane (EDMA, DDMA) containing sulfonic acid group by radiation induced grafted polymerization are sn died for adsorb metal ions (Pb). It has been shown that adsorbed metal ions ($Pb^{2+}$) for the EDMA and DDMA membranes with the density of sulfonic acid groups, 1.40 mmol/g and 2.14 mmol/g, respectively are 13.82 mg/g, 17.37 mg/g, accordingly.

• Environmental Analysis Health and Toxicology
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• v.31
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• pp.11.1-11.6
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• 2016

Objectives A hazard assessment of di(2-ethylhexyl) phthalate (DEHP), a commonly used workplace chemical, was conducted in order to protect the occupational health of workers. A literature review, consisting of both domestic and international references, examined the chemical management system, working environment, level of exposure, and possible associated risks. This information may be utilized in the future to determine appropriate exposure levels in working environments. Methods Hazard assessment was performed using chemical hazard information obtained from international agencies, such as Organization for Economic Cooperation and Development-generated Screening Information Data Set and International Program on Chemical Safety. Information was obtained from surveys conducted by the Minister of Employment and Labor ("Survey on the work environment") and by the Ministry of Environment ("Survey on the circulation amount of chemicals"). Risk was determined according to exposure in workplaces and chemical hazard. Results In 229 workplaces over the country, 831 tons of DEHP have been used as plasticizers, insecticides, and ink solvent. Calculated 50% lethal dose values ranged from 14.2 to 50 g/kg, as determined via acute toxicity testing in rodents. Chronic carcinogenicity tests revealed cases of lung and liver degeneration, shrinkage of the testes, and liver cancer. The no-observed-adverse-effect level and the lowest-observed-adverse-effect level were determined to be 28.9 g/kg and 146.6 g/kg, respectively. The working environment assessment revealed the maximum exposure level to be $0.990mg/m^3$, as compared to the threshold exposure level of $5mg/m^3$. The relative risk of chronic toxicity and reproductive toxicity were 0.264 and 0.330, respectively, while the risk of carcinogenicity was 1.3, which is higher than the accepted safety value of one. Conclusions DEHP was identified as a carcinogen, and may be dangerous even at concentrations lower than the occupational exposure limit. Therefore, we suggest management of working environments, with exposure levels below $5mg/m^3$ and all workers utilizing local exhaust ventilation and respiratory protection when handling DEHP.

• Toxicological Research
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• v.33 no.3
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• pp.239-253
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• 2017

Neodymium is a future-oriented material due to its unique properties, and its use is increasing in various industrial fields worldwide. However, the toxicity caused by repeated exposure to this metal has not been studied in detail thus far. The present study was carried out to investigate the potential inhalation toxicity of nano-sized neodymium oxide ($Nd_2O_3$) following a 28-day repeated inhalation exposure in male Sprague-Dawley rats. Male rats were exposed to nano-sized $Nd_2O_3-containing$ aerosols via a nose-only inhalation system at doses of $0mg/m^3$, $0.5mg/m^3$, $2.5mg/m^3$, and $10mg/m^3$ for 6 hr/day, 5 days/week over a 28-day period, followed by a 28-day recovery period. During the experimental period, clinical signs, body weight, hematologic parameters, serum biochemical parameters, necropsy findings, organ weight, and histopathological findings were examined; neodymium distribution in the major organs and blood, bronchoalveolar lavage fluid (BALF), and oxidative stress in lung tissues were analyzed. Most of the neodymium was found to be deposited in lung tissues, showing a dose-dependent relationship. Infiltration of inflammatory cells and pulmonary alveolar proteinosis (PAP) were the main observations of lung histopathology. Infiltration of inflammatory cells was observed in the $2.5mg/m^3$ and higher dose treatment groups. PAP was observed in all treatment groups accompanied by an increase in lung weight, but was observed to a lesser extent in the $0.5mg/m^3$ treatment group. In BALF analysis, total cell counts, including macrophages and neutrophils, lactate dehydrogenase, albumin, interleukin-6, and tumor necrosis factor-alpha, increased significantly in all treatment groups. After a 4-week recovery period, these changes were generally reversed in the $0.5mg/m^3$ group, but were exacerbated in the $10mg/m^3$ group. The lowest-observed-adverse-effect concentration of nano-sized $Nd_2O_3$ was determined to be $0.5mg/m^3$, and the target organ was determined to be the lung, under the present experimental conditions in male rats.

• Journal of Food Hygiene and Safety
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• v.31 no.5
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• pp.356-364
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• 2016

In vivo genotoxic potential of isoquercetin, a plant common flavonoid, in comparison with quercetin was investigated for the DNA breakage and the clastogenicity endpoints. Male ICR mice were administered by oral gavage for 3 days with $3{\times}0.5%$ carboxymethyl cellulose (CMC), 3 ${\times}$ isoquercetin (250, 500 mg/kg/day), 3 ${\times}$ quercetin (250, 500 mg/kg/day) and 2 ${\times}$ ethyl methanesulfonate (EMS, 200 mg/kg/day). Tissues were collected 48 hours after the first treatment and within 3 hours after the last treatment. The DNA damages were evaluated using Comet assay in liver and stomach, while the clastogenicities were determined using micronucleus test in bone marrow of same animals. The treatment of isoquercetin as well as quercetin did not cause the DNA damages in liver and stomach, and not induce the frequencies of micronucleus polychromatic erythrocytes in bone marrow. In conclusion, isoquercetin as well as quercetin did not cause the DNA breakages and the chromosomal damages in vivo system in these study conditions.

• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.544-547
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• 2003

The objective of this study is to investigate the contamination levels and dispersion patterns of arsenic and heavy metals and to estimate the bioaccessible fraction of the metals in soil and plant samples in the vicinity of the abandoned Songcheon Au-Ag mine. Tailings, soils, plants (Chinese cabbage, red pepper, soybean, radish, sesame leaves, green onion, lettuce, potato leaves, angelica and groundsel) and waters were collected around the mine site. After appropriate preparation, all samples were analyzed for As, Cd, Cu, Pb and Zn by ICP-AES and ICP-MS. Elevated levels of As and heavy metals were found in tailings. Mean concentrations of As in agricultural soils were higher than the permissible level. Especially, maximum level of As in farmland soil was 513 mg/kg. The highest concentrations of As and Zn were found in Chinese cabbage (6.7 mg/kg and 359 mg/kg, respectively). Concentrations of As, Cd, and Zn in most stream waters which are used for drinking water around this mine area were higher than the permissible levels regulated in Korea. Maximum levels of As, Cd and Zn in stream waters were 0.78 mg/L, 0.19 mg/L and 5.4 mg/L, respectively. These results indicate that mine tailings can be the main contamination sources of As and heavy metals in the soil-water system in the mine area. The average of estimated bioaccessible fraction of As in farmland soils were $3.7\%$ (in simulated stomach) and $10.8\%$ (in simulated small intestine). The highest value of bioaccessible fraction of metal in farmland soils was $46.5\%$ for Cd.

• Korean Journal of Environmental Agriculture
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• v.40 no.2
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• pp.92-98
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• 2021

BACKGROUND: Unintentional residual pesticide in soil derived from preceding crops and the transfer to succeeding crops was considered a critical barrier for positive list system (PLS). Thus, an uncertain risk is predicted for ethoprophos applied at cultivation of preceding crop (Korean cabbage) to succeeding crop (spinach). METHODS AND RESULTS: Ethoprophos was treated on soil following the recommended dose and 5 times dose according to the safe use guidelines for Korean cabbage after seeding. On the 4 days after harvesting of preceding crop, spinach was sowed. The initial residual amounts of ethoprophos on soil (7.081-19.493 mg/kg) were decreased to 3.832-7.218 mg/kg until the harvest of Korean cabbage, and then finally decreased to 0.011-0.079 mg/kg after spinach cultivation. The uptake rates of ethoprophos from soil by Korean cabbage were 0.01-0.03% and distributed to root (0.150-0.903 mg/kg) and shoot (0.021-0.151 mg/kg), respectively. The residual amounts of uptake and translocation from preceding crop cultivated soil to spinach edible part were found to be below LOQ. CONCLUSION: The plant back internal (PBI) for ethoprophos is not recommended during sequential cultivation of leafy vegetables, since the residual amounts of ethoprophos in spinach were less than MRL (0.02 mg/kg).