• Journal of Nutrition and Health
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• v.49 no.5
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• pp.277-287
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• 2016

Purpose: This study was performed to compare total phenolic contents, in vitro antioxidant capacity, and reduction effect of Korean food groups on ex vivo DNA damage in human cells and analyze correlations between each indicator. Methods: Vegetable foods in the Korean diet based the results of the KNHANES V-2 (2011) were classified into 10 food groups: cereals, fruits, vegetables, nuts, kimchi, seaweeds, potatoes, mushrooms, legumes, and oils. Eighty-four foods constituted more than 1% of the total intake in each food group and finally designated as vegetable foods in the Korean diet. Total phenolic content of each food group was measured. Further, in vitro antioxidant capacity was measured based on DPPH radical scavenging assay, TEAC assay, and $ORAC_{ROO{\cdot}}$ assay. Ex vivo DNA damage in human lymphocytes was assessed using comet assay. Results: Total phenolic contents of food groups of the Korean diet increased in the order of mushrooms, fruits, vegetables, seaweeds, and kimchi. Meanwhile, antioxidant rankings of food groups as mean values from the three in vitro test methods increased in the order of mushrooms, seaweeds, vegetables, kimchi, and fruits. Protection against ex vivo DNA damage in human lymphocytes was highest in mushrooms, followed by vegetables, fruits, seaweeds, and kimchi. The rankings of the food groups for total phenolic content, in vitro DAC, and ex vivo DNA protection activity were similar, and correlations between each indicator were significantly high. Conclusion: Mushrooms, fruits, vegetables, and seaweeds among the tested food groups in the Korean diet showed high total phenolic contents, in vitro antioxidant capacities, and protection against DNA damage. Correlations between each indicator in terms of total phenolic content, in vitro antioxidant capacity, and ex vivo DNA protection between each food group were found to be particularly high.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.10 no.1
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• pp.93-103
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• 2000

The purpose of this case study is to report a case of lung cancer with exposure to welding fumes of welders in Korea and to demonstrate the causal relationship with exposure to welding fumes, especially with nickel and hexavalent chromium. The case is 47 years old, and had been engaged in welding, gas cutting, grinding and gousing on mild, stainless steel and nickel steel for 11 years from 1982 to 1993, and have been engaged in cleaning steel rollers with a cleaning oil in the same work shop since 1993. The level of welding fume exceeded the occupational exposure limit of $5mg/m^3$ established by the Korean Ministry of Labor and American Conference of Government Industrial Hygienists (ACGIH). Especially, detectable hexavalent chromium and nickel was generated during welding, gousing on stainless and nickel steel. However, there was no ventilation systems(local and dilution) and no personal protection. There is several evidence that the past (1983-1993) exposure would be higher than the present. In conclusion, the lung case could be associated with his task including welding, gousing, and this association could be attributed to carcinogenic potential of the nickel and chromium in the fume.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.8 no.2
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• pp.209-223
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• 1998

The aim of this study was to evaluate welders' exposure to hexavalent chromium (Cr(VI)) and nickel (Ni) during welding operations in a Korean shipyard. The airborne Cr(VI) and Ni concentrations were measured during metal inert gas (MIG) welding on mild and stainless steel, and manual metal arc (MMA) welding on mild steel. The geometric mean (GM) of Cr(VI) concentrations inside the welding helmet during MIG welding on mild steel were $0.0018mg/m^3$ inside a ship section, and $0.0015-0.0026mg/m^3$ at the welding shops. All of the personal breathing zone air samples were below the American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value ($TLV^{(R)}$) of $0.01mg/m^3$. Conversely, eighty-eight percent(21 of 24) of the personal breathing zone air samples exceeded the National Institute for Occupational Safety and Health (NIOSH) recommended exposure limit of $0.001mg/m^3$. Ni was not detected on 20 of 23 air samples collected during MIG welding on mild steel. The three Ni samples above the limit of detection ranged from 0.015 to $0.044mg/m^3$. The GM of Cr(VI) concentrations during MMA welding on mild steel were $0.0013mg/m^3$, but Ni was not detected in the air samples during this operation. It is assumed that the airborne Cr(VI) and Ni during mild steel welding were derived from the base metals which contained about 0.03% Cr and 0.03% Ni. The GM of airborne total Cr, Cr(VI) and Ni concentrations during MIG welding on stainless steel were 4.02, 0.13 and $0.86mg/m^3$, respectively, and the levels of Cr(VI) and Ni were above the ACGIH-$TLV^{(R)}$. Cr(VI) comprised about 35.5% of the total chromium(Cr) from MIG welding on mild steel, and about 8.4% of total Cr from MIG welding on stainless steel. The ratios of Cr(VI) to total Cr were significantly different among welding shops. It was concluded that welders were exposed to high levels of Cr(VI) and Ni during welding on stainless steel, and were exposed to low levels of Cr(VI) even during welding on mild steel.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.3 no.1
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• pp.110-126
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• 1993

Worker exposures to total chromium, hexavalent chromium (VI), sulfuric acid and alkaline dust at electroplating operations and worker exposures to trichloroethylene (TCE) and methyl chloroform (MCM) at degreasing operations in eleven small industrial plants were evaluated. Appropriate local exhaust ventilation systems for both operations were designed and recommended. Results of the study are summarized as follows ; 1. Out of 134 measurements for airborne hexavalent chromium concentrations, seven were exceeding the Korean occupational health standard of $50{\mu}g/m^3$ and 45 were exceeding the NIOSH standard of $1{\mu}g/m^3$. With an exception of one measurement, concentrations of total chromium were below the Korean standard of $500{\mu}g/m^3$. 2. Worker exposures to chromium were closely related to the existing control methods at the electroplating operations. Local exhaust systems, partial coverage of the tank surface, and antifoaming agents on liquid surface were adopted as control methods. 3. With an exception of one sample, airborne concentrations of sulfuric acid and alkaline dusts were below the applicable occupational heatlth standards. 4. Three plants indicated that airborne concentrations of TCE and MCM were exceeding the Korean standards. Other plants showed lower concentrations than the standards. It should be noted that generally, the activities and workloads on the day of surveys were less than normal. 5. Since the most existing ventilation systems did not satisfy the ACGIH criteria, the ventilation systems should be improved. Some examples for designing appropriate ventilation systems are presented.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.3 no.1
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• pp.22-36
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• 1993

This study was conducted to evaluate the charcoal tube sampling method for carbon disulfide in the air. Breakthrough was investigated according to flow rate, sampling time and air volume. Also the storage stability by storage method and time was investigated. The results are summarized as follows. 1. The samples stored at room temperature($28.2^{\circ}C$), refrigerator($3.8^{\circ}C$) and freezer($-15.6^{\circ}C$) were analyzed every week to five weeks. At one week storage at room temperature, 3.5% of $CS_2$ in the front section of the charcoal tube migrated into the back section and 57.7% at five weeks. The amount of $CS_2$ in the back section of the charcoal increased continuously by storage time. Migration of $CS_2$ was slow at refrigerator, and stopped occur at freezer. Recovery rate $CS_2$ was 52-82% at room temperature and 92-101% at refrigerator, based on the amount at freezer as a reference value. Thus loss was observed at room temperature. 2. When 6-48 L of fresh air were passed through tubes with spiked amounts of 0.379 and 0.759mg sample, the amounts of $CS_2$ in the back section of charcoal were 5.7-132.4 and 0-92% of the amount in the front section, respectively. The total recovery rates of$CS_2$ from 0.379 and 0.759mg spiked sample were 35.7-101.0% and 9l.3-100.1%, respectively. $CS_2$ loss was observed in 0.379mg spiked sample, but not in 0.759mg spiked sample. In the spiked samples, the amount of $CS_2$ in the back section of charcoal was not affected by flow rate when the air volume was controlled. The amount of $CS_2$ in the back section of charcoal increased over sampling time. And the faster the flow rate, the more the migration amount when the sampling time was the same. 3. A known concentration, 10 ppm of $CS_2$, was produced in a 200 L Tedlar bag. When the air volume was 24, 36, 48 L, breakthrough was 5.8, 16.9, 47.4%, respectively. The sampling flow rate of 0.05, 0.1, 0.2 Lpm did not change the breakthrough rate. Breakthrough increased over sampling time. And the faster the flow rate, the more the breakthrough, when the sampling time was the same.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.7
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• pp.1053-1062
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• 2011

Reactive oxygen species (ROS), including singlet oxygen (${O_2}^1$), superoxide anion radical ($O_2{\cdot}^-$), hydroxyl radical ($HO{\cdot}$), peroxyl radical ($ROO{\cdot}$), hydrogen peroxide ($H_2O_2$), and hypochlorous (HOCl), are generated as byproducts of normal cellular metabolism. ROS induce damage to many biological molecules, such as lipids, proteins, carbohydrates, and DNA. It is widely believed that some degenerative diseases caused by ROS can be prevented by the high intake of fruits and vegetables due to their antioxidant activities. Recently, research on natural antioxidants has become increasingly active in various fields. Several assays have been developed to measure the total antioxidant capacity of antioxidants in fruits and vegetables in vitro. These assays include those for DPPH radical scavenging activity, SOD-like activity, total polyphenol content, oxygen radical absorbance capacity, reducing power, trolox equivalent antioxidant capacity (ABTS assay), single-cell gel electrophoresis (comet assay), and a cellular antioxidant activity assay. Because different antioxidant compounds may act through different mechanisms in vitro, no single assay can fully evaluate the total antioxidant capacity of foods. Due to the complexity of the composition of foods, it is important to be able to measure antioxidant activity using biologically relevant assays. In this review, recently used assays were selected for extended discussion, including a comparison of the advantages and disadvantages of each assay and their application to fruits and vegetables.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.7 no.2
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• pp.181-195
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• 1997

The purpose of this study was to investigate factors affecting the composition and concentrations of fumes generated from various types of welding processes. The results are as follows. 1. Iron(Fe), zinc(Zn) and manganese(Mn) were predominant in Welding fumes. The Fe content in total fumes was 25.5% in coated electrode and 28.2% in $CO_2$ are welding, and the Zn content was 4.5% and 9.1%, respectively, and the Mn was 3.6% and 7.8%, respectively. 2. It was found that the important factors determining composition and concentration of fumes were type of industries, type of welding processes, type and composition of electrodes, composition of base metals, confinement of workplaces or condition of ventilation, work intensity, coated metals such as lead and Zn in paint. 3. The Mn content in airborne fumes was highly correlated with that of electrode(r=0.77, p<0.01) and was about 4 times higher than that in electrodes or base metals. The results lindicate that Mn is well evaporated into air during welding. The higher vapor pressure of Mn may explain this phenomenon. 4. the airborne total fume concentrations were significantly different among types of industries(p<0.001). The airborne total fume concentration was higher in order of sleel-structure manufacturing($GM=15.1mg/m^3$), shipbuilding($GM=13.2mg/m^3$), automobile-component manufacturing ($GM=7.8mg/m^3$) and automobile assembling industry($GM=3.0mg/m^3$) 5. The airbone total fume concentration was 6 times higher in $CO_2$ welding than in coated electrode welding, and approximately 3 times higher in confined area than in open area, in steel-structure manufacturing industry. 6. The concentration of welding fume outside welding helmet was about 2 times higher than that inside it. It is recommened that air sampling be done inside helmet to evaulate worker's exposure accurately, for it has an outstanding effect on reducing worker exposure to fumes and other contaminants.

• Journal of Marine Bioscience and Biotechnology
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• v.7 no.2
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• pp.52-57
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• 2015

The purpose of this study was to investigate a relationship between ultraviolet radiation and initial cell density (ICD) of microalgae using a floating marine photobioreactor (PBR). To examine the effect of ultraviolet (UV) radiation in sunlight on biomass productivity as a function of ICD, 0.5-L floating PBRs covered with or without UV cut-off film were placed in an outdoor rectangular tank containing 200 L of water. At the lower ICDs, 0.01 and 0.05 g/L, biomass productivities in the PBRs without UV cut-off film decreased by $278{\pm}21%$ and $222{\pm}3%$ compared with those with the film, respectively. In contrast, the presence of UV cut-off film did not have a significant effect on biomass productivities at the higher ICDs, 0.25 and 1.25 g/L. When the differences in biomass productivity made by the UV cut-off film were plotted against the sum of cell projection area per light receiving area of the PBR, the results revealed that the inhibitory effect of UV on biomass productivity can be negligible when the sum of cell projection area is equal to the light receiving area of the PBR. These results show that photoinhibition caused by UV radiation could be eliminated via operating the PBR with a proper ICD.

• Applied Chemistry for Engineering
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• v.10 no.4
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• pp.543-547
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• 1999

The utilization of fly-ash containing high levels of the unburned carbon was investigated. In this study adsorbents were manufactured from fly-ash ad a raw material and the manufactured adsorbents were applied to the waste-water treatment including heavy metals. Varying the anthracite(Jangsung coal) content, three types of pellet were made. The carbon content of pellet increased appreciably upon the addition of anthracite. After carbonization and activation using the pellets, adsorbents showed following characteristics; the range of hardness was between 85% and 96%, iodine number was from 100 mg/g to 300 mg/g. In proportion to the anthracite addition, hardness and iodine number increased. Through the adsorption experiments of heavy metals, removal efficiencies of Pb and Cr by manufactured adsorbents were over 90%. In case of fly-ash, removal efficiencies of Pb and Cr were 31.5% and 5.6% respectively. The reason why removal capacities of manufactured adsorbents were higher than fly-ash was postulated that adsorption capability was improved by unburned carbon and $SiO_2$ which included in fly-ash during steam activation.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.4 no.2
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• pp.168-179
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• 1994

In some ceramic industries, worker exposure to dust, crystalline free silica and lead were determined and evaluated. The conclusions are as follows. 1. Crystalline silica in bulk samples was 10.5 % in sanitary ware industry, 9.4 % in tile industry, and 2.1 % in ceramic insulator industry respectively. The free silica content of air filter sample was 8.03 % in table ware industry, 5.59 % in sanitary ware industry, and 1.32 % in ceramic insulator industry. Because silica content in ceramic dust is relatively high, it is should be considered silica as important factor in evaluating for ceramic industry. 2. The silica contents in dust from tile, sanitary ware and table ware industries are above 5%, it should be classified as "Type" 2 dust. 3. The airborne concentration of respirable crystalline silica was $27.9{\mu}g/m^3$ in a sanitary ware factory and $5.8{\mu}g/m^3$ in a ceramic insualtor factory. Three of ten samples sampled the above factories were exceeded the occupational exposure levels, $100{\mu}g/m^3$. 4. Geometric mean(GM) of total dust in 11 factories was $1.00mg/m^3$ and GM of respirable dust concentration in 5 factories was $0.33mg/m^3$. Sanitary ware industry had the highest concentration of total dust, $1.62mg/m^3$ and of respirable dust, $0.88mg/m^3$. 5. Average lead concentration in air was $0.05mg/m^3$ in glazing process of 2 factories manufacturing table ware. Five of ten sample(50%) were exceeded $0.05mg/m^3$. Therefore lead exposure in pottery industry should be considered as important problem.