• Composites Research
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• 제21권6호
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• pp.8-14
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• 2008

가로등은 운전자의 안전을 위한 필수적인 도로 부속구조물이며, 대부분 강재 등주를 사용하고 있다. 강재등주는 부식이 발생하여 내구성을 감소시키고, 도시미관을 저해하므로 스테인레스 제품이나 주철재 등을 사용하기도 한다. 그러나 주철재 및 스테인레스 등주를 사용하더라도 부식에 대한 위험성을 완전히 배제할 수 없고, 높은 강도와 강성은 충돌시 운전자의 안전을 위협하는 요인이 되고 있다. 따라서 새로운 형태의 등주 시스템의 개발이 요구되고 있다. 기존 등주의 문제점을 보완하기 위해 최근 알루미늄 합금을 사용한 등주가 개발되어 사용되고 있다. 알루미늄은 재료적 특성상 단위중량당 강도가 높고 부식에 대한 저항성이 매우 커서 그 활용성을 크게 증대될 것으로 예측되나 강계에 비해 강성과 강도가 낮기 때문에 구조적 안전성에서 문제점이 제기되고 있어 구조거동에 대한 연구가 필요하다. 이 연구는 현재 가로등 등주로 사용되고 있는 강재 및 알루미늄 등주에 대한 휨, 압축실험 등을 수행하여 알루미늄 등주의 구조거동을 조사하였고, 기존 강재등주와 비교하여 효율성 및 안전성을 평가하였다.

• Toxicological Research
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• 제33권1호
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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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• 제3권3호
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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).

• 한국식품위생안전성학회지
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• 제34권1호
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• pp.13-21
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• 2019

본 연구는 2018년 국내식품 중 신규 기준설정 예정 농약인 스트렙토마이신의 잔류 농약 검사를 위한 공정시험법을 마련하기 위하여 수행하였다. 스트렙토마이신은 아미노글리코사이드계 항생제로 소, 돼지, 닭 등 가축 및 가금에 동물용의약품으로 허가되어 세균성 질병치료에 사용되고 있다. 또한 우리나라에서는 감귤, 매실, 참다래, 복숭아 등에 발병하는 세균성 병해를 방지하기 위하여 농약으로 등록되어 있다. 국내에서는 스트렙토마이신의 잔류물의 정의를 스트렙토마이신과 디히드로스트렙토마이신의 합으로 정하여 관리하고 있으며 잔류허용기준은 동물용의 약품으로 사용 시 불검출부터 1.0 mg/kg까지 설정되어 있다. 농약으로 사용 시 농산물 중 잔류허용기준은 설정되어 있지 않으며 식품공전의 시험법 역시 동물용의약품에 적용되는 시험법으로 설정되어 있다. 이에 농산물 중 잔류허용기준 설정을 위한 시험법 마련이 시급하여 본 연구에서는 식품공전에서 정하고 있는 대표농산물 5종(현미, 감자, 대두, 감귤, 고추)을 포함한 잔류시험법을 개발하고자 하였다. 따라서 수용성 유기용매인 메탄올의 적용과 포름산을 이용한 pH 조절을 통한 추출법 및 HLB 카트리지를 이용한 정제법을 최적화하여 LC-MS/MS에 의한 분석법을 확립하였다. 스트렙토마이신과 디히드로스트렙토마이신의 시험법 정량한계는 0.01 mg/kg으로 PLS 제도에 맞는 잔류허용기준 수준을 만족하였다. 스트렙토마이신과 디히드로스트렙토마이신의 평균 회수율은 각각 72.0~116.5%와 72.1~116.0%이었고, 상대표준편차는 각각 12.3%와 12.5% 이하로 조사되어 이러한 결과는 국제식품규격위원회 가이드라인(CAC/GL 40-1993, 2003)의 잔류농약 분석기준 및 식품의약품안전평가원의 '식품등 시험법 마련 표준절차에 관한 가이드라인(2016)'에 적합한 수준임을 검증하였다. 따라서 본 연구에서 개발한 시험법은 농산물 중 스트렙토마이신의 잔류검사를 위한 공정시험법으로 활용할 수 있으며 유사 농산물에 대한 적용도 가능하리라 판단되어 향후 국내 농산물 중 농약의 잔류허용기준 신설 및 잔류농약 검사의 기초자료로 활용 가능할 것이다.

• 멤브레인
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• 제19권4호
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• pp.333-340
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• 2009

본 연구의 목적은 중금속 흡착을 위한 방사선 그라프트 중합법에 의한 이온교환막의 성능 향상을 위한 것이다. 그라프트 체인의 이온교환기에 의해 체인이 막의 pore를 방해하여 투과유속이 크게 저하되는 문제를 해결하고자 그라프트 체인과 체인사이를 N-ethyleneglycoldimethacrylate계 가교제를 첨가하여 투과유속이 저하되는 문제를 해결하고자 했다. 이때 사용된 가교제는 길이가 서로 다른 ethylene glycol dimethacrylate (EDMA)와 diethylene glycol dimethacrylate (DDMA)를 사용하였다. GMA 막에 가교제가 첨가된 이온교환막에 술폰산기를 첨가한 막을 이용하여 중금속 이온($Pb^{2+}$) 흡착을 하였다. 술폰산기 밀도가 1.40 mmol/g인 EDMA막은 13.82 mg/g을 흡착하였고, 술폰산기 밀도가 2.14 mmol/g인 DDMA막은 17.37 mg/g의 흡착량을 보였다.

• Environmental Analysis Health and Toxicology
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• 제31권
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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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• 제33권3호
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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.

• 한국식품위생안전성학회지
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• 제31권5호
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• pp.356-364
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• 2016

식물에서 흔히 존재하는 isoquercetin의 유전독성을 평가하기 위하여 최종평가항목인 DNA 절단 및 염색체 손상을 quercetin과 비교 평가하였다. 7주령의 수컷 ICR 마우스를 사용하였고 3일 동안 시험물질을 경구로 투여하였다. 부형제로 0.5% carboxymethylcellulose를 사용하였고 isoquercetin과 quercetin은 각각 250, 500 mg/kg/day로 투여하였으며, 양성대조물질로 ethyl methanesulfonate 200 mg/kg/day를 사용하였다. 일차 투여 후 48시간에 그리고 마지막 투여 후 3시간 내에 부검하였고 조직을 적출하였다. DNA 손상은 Comet assay를 사용하여 위와 간세포에서 관찰하였고, 소핵시험은 골수세포에서 소핵 분석방법을 사용하여 평가하였다. 두 가지 유전독성 시험을 동일 마우스를 사용하여 수행하였다. 그 결과, isoquercetin과 quercetin의 경구 투여는 500 mg/kg/day에서도 위와 간에서 DNA 손상을 초래하지 않았으며 골수세포에서 소핵을 유발하지 않았다. 따라서 본 연구에서 사용한 플라보노이드는 본 실험 조건하에서 유전독성을 유발하지 않는 것으로 사료된다.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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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.

• 한국환경농학회지
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• 제40권2호
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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).