• Progress in Medical Physics
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• v.27 no.3
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• pp.105-110
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• 2016

Sparse angular sampling has been studied recently owing to its potential to decrease the radiation exposure from computed tomography (CT). In this study, we investigated the analytic reconstruction algorithm in sparse angular sampling using the sinogram interpolation method for improving image quality and computation speed. A prototype of the spectral CT system, which has a 64-pixel Cadmium Zinc Telluride (CZT)-based photon-counting detector, was used. The source-to-detector distance and the source-to-center of rotation distance were 1,200 and 1,015 mm, respectively. Two energy bins (23~33 keV and 34~44 keV) were set to obtain two reconstruction images. We used a PMMA phantom with height and radius of 50.0 mm and 17.5 mm, respectively. The phantom contained iodine, gadolinium, calcification, and lipid. The Feld-kamp-Davis-Kress (FDK) with the sinogram interpolation method and Maximum Likelihood Expectation Maximization (MLEM) algorithm were used to reconstruct the images. We evaluated the signal-to-noise ratio (SNR) of the materials. The SNRs of iodine, calcification, and liquid lipid were increased by 167.03%, 157.93%, and 41.77%, respectively, with the 23~33 keV energy bin using the sinogram interpolation method. The SNRs of iodine, calcification, and liquid state lipid were also increased by 107.01%, 13.58%, and 27.39%, respectively, with the 34~44 keV energy bin using the sinogram interpolation method. Although the FDK algorithm with the sinogram interpolation did not produce better results than the MLEM algorithm, it did result in comparable image quality to that of the MLEM algorithm. We believe that the sinogram interpolation method can be applied in various reconstruction studies using the analytic reconstruction algorithm. Therefore, the sinogram interpolation method can improve the image quality in sparse-angular sampling and be applied to CT applications.

• Korean Journal of Environmental Agriculture
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• v.40 no.1
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• pp.60-66
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• 2021

BACKGROUND: The concern over heavy metal(loid)s in arable land and agricultural products increases for public health in recent years. This study aims to identify transition characteristics of heavy metal(loid)s and to assess dietary risk in barley grown at the major producing districts in Korea. METHODS AND RESULTS: The soil and barley samples were collected from 38 locations around the major producing districts at Jeollabuk-do in Korea for the propose of examining the concentrations of heavy metal(loid)s. The 34 barley samples were separately purchased on the market for the same survey. The average concentration and range of arsenic (As), cadmium (Cd) and lead (Pb) in barley grown at the major producing districts in Korea were 0.037 (0.016-0.094), 0.028 (0.004-0.083) and 0.137 (0.107-0.212) mg kg-1, respectively. Currently, the maximum allowable level for barley Pb is set at 0.2 mg kg-1 in Korea, and the monitoring results suggested that some samples exceeded the maximum allowable level and required appropriate farming management. Bio-concentration factor values by heavy metal(loid)s in barley were high at Cd, copper (Cu) and zinc (Zn), similar to other crops, while As and Pb were low, indicating low transferability. CONCLUSION: Human exposure to As, Cd and Pb through dietary intake of barley might not cause adverse health effects due to relatively low concentrations, although the Pb in some barley was detected higher than the maximum allowable level. Further study on uptake and accumulation mechanism of Pb by barley might be required to assess the human health risk associated with soil contamination.

• Journal of Food Hygiene and Safety
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• v.16 no.4
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• pp.324-332
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• 2001

Foods constitute a large portion of heavy metal exposure toward general population and attract a deep concern with respect to assuring human health. This study summarized published data in Korea on the content, and dietary intake of heavy metals and assessed their risk potential in comparison with foreign data. An analysis for the yearly fluctuation of metal contents including arsenic, cadmium, mercury and lead by flood group (marine fishes, coastal shellfishes, freshwater fishes, cereal grains) exhibited a decreasing trend from the 1970s to the 1990s. When compared with domestic standards of heavy metals, their mean contents were below the limit and their maximum values seldom exceeded the limit. The data on the dietary intake of heavy metals by Koreans showed a decreasing trend from the 1980s to the 1990s. The average intakes offs and Hg were 6∼8% and those of Cd and Pb were 50∼80% of PTWI(provisional tolerable weekly intake), all of which were below the tolerance. As the extreme intakes of these metals may exceed the PTWI, a careful assessment for them may be necessary. Dietary intakes of Cd, Hg and Pb by Koreans lie in the mid-level among countries cited in the GEMS/Food monitoring data. As fishery foods are suspecious of contamination with Hg, Cd and As, and floods in general are with Pb, it is necessary to establish legal limits for these metals and monitor any progress of their contamination. Furthermore, overall assessment of exposure to heavy metals from all sources including floods, air, drinking water and occupation should be made in order to confirm the dietary risk factors and to assure the safety of food resources.

• Environmental Analysis Health and Toxicology
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• v.28
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• pp.7.1-7.9
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• 2013

Objectives We investigated the particle mass size distribution and chemical properties of air pollution particulate matter (PM) in the urban area and its capacity to induce cytotoxicity in human bronchial epithelial (BEAS-2B) cells. Methods To characterize the mass size distributions and chemical concentrations associated with urban PM, PM samples were collected by a 10-stage Micro-Orifice Uniform Deposit Impactor close to nearby traffic in an urban area from December 2007 to December 2009. PM samples for in vitro cytotoxicity testing were collected by a mini-volume air sampler with $PM_{10}$ and $PM_{2.5}$ inlets. Results The PM size distributions were bi-modal, peaking at 0.18 to 0.32 and 1.8 to $3.2{\mu}m$. The mass concentrations of the metals in fine particles (0.1 to $1.8{\mu}m$) accounted for 45.6 to 80.4% of the mass concentrations of metals in $PM_{10}$. The mass proportions of fine particles of the pollutants related to traffic emission, lead (80.4%), cadmium (69.0%), and chromium (63.8%) were higher than those of other metals. Iron was the dominant transition metal in the particles, accounting for 64.3% of the $PM_{10}$ mass in all the samples. We observed PM concentration-dependent cytotoxic effects on BEAS-2B cells. Conclusions We found that exposure to $PM_{2.5}$ and $PM_{10}$ from a nearby traffic area induced significant increases in protein expression of inflammatory cytokines (IL-6 and IL-8). The cell death rate and release of cytokines in response to the $PM_{2.5}$ treatment were higher than those with $PM_{10}$. The combined results support the hypothesis that ultrafine particles from vehicular sources can induce inflammatory responses related to environmental respiratory injury.

• Environmental Analysis Health and Toxicology
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• v.21 no.2 s.53
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• pp.153-163
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• 2006

Essential metals have been known to interact with non-essential toxic metals in the aspects of absorption, transport and deposition in the body. Iron deficiency has been reported to increase lead and/or cadmium absorption. The relation between iron and lead has been understood well in children but not in adults. Two hundred seventy adults (118 males and 152 females) were recruited from 3 different residental areas (rural, coastal and urban) to investigate the effects of environmental lead exposure on body iron status. The subjects were interviewed for life-style and diet of the last 24 hours, and measured for blood lead and body iron. The lead concentration in the whole blood was determined by a flameless method using an atomic absorption spectrophotometry. The body iron was evaluated with values of hemoglobin, hematocrit, RBCs, serum total iron, unsaturated iron binding capacity, total iron binding capacity and ferritin. The mean concentration of blood lead in adult was $3.31{\mu}g/dL$. The concentration was higher in male ($3.97{\mu}g/dL$) than in female ($2.86{\mu}g/dL$). The blood lead was influenced by residental area, life-style, smoking and drinking, occupation and diet habit of subjects, but not by age. A positive correlation was observed between the blood lead level and the serum iron or ferritin. These results suggest that environmental lead exposure in Korean adult may not be higher than other developed and developing countries. It is further indicated that blood lead in adult could be influenced by life-style, and environmental and genetic factors but no inverse relation with body iron as shown in children.

• Journal of Food Hygiene and Safety
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• v.34 no.4
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• pp.325-333
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• 2019

The present study was carried out to identify the distribution characteristics of heavy metals in ginseng and wood-cultivated ginseng reduction of dietary exposure. Samples of ginseng and wood-cultivated ginseng were collected from 14 and 5 regions across Korea, respectively. Lead (Pb), cadmium (Cd) and arsenic (Ar) were detected by ICP-MS after microwave digestion, whereas aluminum (Al) was determined using ICP. Cultivated ginseng peels were 16.2% of whole root, while the peels and fine roots amounted to 21.8% and 16.8% of whole wood-cultivated ginseng, respectively. Taking into account the weight and concentration of the heavy metals by root part, their distribution ratios were calculated and compared. The cultivated ginseng peels contained 40.3% Pb, 25.9% Cd, 47.6% As, and 89.9% Al. Meanwhile, heavy metals consisting of 27.2% Pb, 28.2% Cd, 48.3% As, and 56.8% Al were distributed in the peels of the wood-cultivated ginseng. There was no significant difference between the peels and fine roots of the wood-cultivated ginseng with respect to the distribution proportion of heavy metals, except for Al. These results indicate that the level of dietary exposure to heavy metals could be reduced by peeling ginseng and wood-cultivated ginseng prior to consumption.

• Fisheries and Aquatic Sciences
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• v.25 no.12
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• pp.626-636
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• 2022

Shellfish are exoskeleton-bearing aquatic invertebrates that consume various organic and inorganic substances floating in seawater through filter feeding. Heavy metals are known as absorbed and accumulated in seawater. Some of the toxic heavy metals are highly accumulated in seawater, and exposure to them can cause a variety of risks to the human body. Since Koreans like to eat seafood, they are more likely to be exposed to contaminated seafood with heavy metals. In this study, nine types of heavy metals were analyzed on ten different shellfish species in the coastal area of South Korea. The risk assessment was also done on shellfish in which heavy metals were detected. Zinc (Zn) and copper (Cu) were identified at an average of 56.7 mg/kg (6.70 to 466 mg/kg) and 13.2 mg/kg (0.064 to 143 mg/kg), respectively. Lead (Pb) average of 0.208 mg/kg (0.000750 to 1.02 mg/kg), cadmium (Cd) average of 0.454 mg/kg (0.0388 to 1.56 mg/kg) and mercury (Hg) average of 0.0266 mg/kg (0.00548 to 0.174 mg/kg) were identified. Additionally, arsenic (As), chromium (Cr), nickel (Ni), and silver (Ag) were also identified as average concentrations of 4.02 (0.460 to 15.0 mg/kg), 0.167 (< limit of quantification [LOQ] to 0.820 mg/kg), 0.281 (< LOQ to 1.46 mg/kg), and 0.158 mg/kg (< LOQ to 1.15 mg/kg). The result indicates that the monitoring results of heavy metals in most shellfish satisfied the Korean standard. However, Pb and Cd have exceeded some foreign standards, such as the United States and the EU. The permissible human exposure calculated using the heavy metal intake and detection amount was lower than the Joint FAO/WHO Expert Committee on Food Additives human safety standard, and the risk of heavy metals from shellfish consumption was at an acceptable level.

• Korean Journal of Food Science and Technology
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• v.43 no.5
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• pp.525-531
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• 2011

This study was conducted to examine the contents of lead (Pb), cadmium (Cd), arsenic (As), and mercury (Hg) in meat and meat products in Korea. The contents of Pb, Cd, As, and Hg in 466 samples of beef, pork, chicken, duck, ham, and sausage were measured using inductively coupled plasma mass spectrometry or a mercury analyzer. Wet ashing and microwave method were compared, and the recovery and reproducibility of the microwave method were better than those of wet ashing for meat and meat products. The recovery of the microwave method was 98.1% for Pb, 104.6% for Cd, and 103.4% for As, respectively. The best result was obtained through digestion using an acid mixture ($HNO_3$/$H_2O_2$, 6:2). Hg content was measured using a mercury analyzer. As a result, the contents of Hg and Cd in samples were lower than those of Pb and As. The average contents of Pb were 0.009 mg/kg in beef, 0.010 mg/kg in pork, 0.006 mg/kg in chicken, 0.007 mg/kg in duck, 0.005 mg/kg in ham, and 0.009 mg/kg in sausage. The average Cd contents were 0.0004 mg/kg in beef, 0.0004 mg/kg in pork, 0.0005 mg/kg in chicken, 0.0012 mg/kg in duck, 0.0015 mg/kg in ham, and 0.0019 mg/kg in sausage. The average As contents were 0.016 mg/kg in beef, 0.004 mg/kg in pork, 0.021 mg/kg in chicken, 0.010 mg/kg in duck, 0.014 mg/kg in ham, and 0.018 mg/kg in sausage. The average Hg contents were 0.713 ${\mu}g/kg$ in beef, 0.902 ${\mu}g/kg$ in pork, 0.710 ${\mu}g/kg$ in chicken, 0.796 ${\mu}g/kg$ in duck, 1.141 ${\mu}g/kg$ in ham, and 1.052 ${\mu}g/kg$ in sausage. Based on the results of the National Health and Nutrition Survey 2005, the levels of dietary exposure to heavy metal contaminants in meat and meat products were compared with the provisional tolerable weekly intake(PTWI) established by the Joint FAO/WHO Expert Committee on Food Additives. The average dietary exposure of the general population from meat and meat products was 0.03-0.2% of PTWI for Pb, Cd, As, and Hg, which indicates a safe level for public health at present.

• Korean Journal of Ecology and Environment
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• v.56 no.4
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• pp.320-329
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• 2023

Cadmium (Cd), a heavy metal found in the aquatic environment, accumulates in organisms through the food chain. In the study, we investigated the survival rates, measurement of body Cd levels, and expression analysis of the stress response genes (Heat shock protein 70: HSP70 and Heat shock protein 60: HSP60) and antioxidant enzyme Glutathione S-Transferases (GST) on benthic oligochaete worm Tubifex tubifex exposed three concentrations of Cd, to analyze the bioaccumulation and changes of stress gene expressions to exposure toxicity of the Cd-spiked sediment. Survival rates of T. tubifex exposed to the Cdspiked sediment were 93% at 0.4 mg kg^-1 Cd, 96% at 1.87 mg kg^-1 Cd, and 93% at 6.09 mg kg^-1 Cd for 10 days. Cd concentration in the body of T. tubifex was higher than that in the sediment. After Cd exposures for 10 days, the body Cd levels were 18.4 mg kg^-1, 13.06 mg kg^-1, and 79.11 mg kg^-1 at exposed three concentrations of Cd, respectively. Upregulation of HSP70 gene expression was observed at all concentrations of exposed Cd as a time-dependent manner, whereas transcriptional expression of the HSP60 gene increased as a timedependent manner in T. tubifex exposed to the relative high concentration (6.09 mg kg^-1) of Cd. However, GST gene expression increased on day 1 at all concentrations after Cd exposures, and then downregulated until 10 days. These results indicate to ecotoxicological and molecular effects in benthic oligochaete worm T. tubifex to Cd-spiked sediment and provide the basic information for the utilization of environmental toxicity assessment using the T. tubifex as a aquatic pollution indicator species.

• Journal of Environmental Impact Assessment
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• v.25 no.6
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• pp.502-513
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• 2016

In this study, heavy metal distributions in the tissues of feral pigeon (Columba livia) were characterized using samples collected from bio-monitoring sites (Hangang Park and Hampyeong Park) of the NESB (National Environmental Specimen Bank), Korea, in order to evaluate the feasibility of feral pigeons as an indicator for the environmental monitoring. Cadmium (Cd) was analyzed to be accumulated in kidneys at higher concentration than in the other tissues. Such trend can also be found in the reviews on the Cd accumulations of the 34 cases including 17 avian species which showed that 31 cases had the highest Cd concentrations in the kidney among tissues. However, lead (Pb) was found to be richest in the bones in this study. 17 cases out of 30 reviewed cases had the highest Pb concentration in bones, whereas other 10 cases showed the highest concentration in kidneys, and 3 cases in livers. Therefore, kidneys together with bones can be a main target organ to test cadmium exposure to different habitat environments depending on physiological traits of birds. Zinc (Zn) was found to be the highest concentration in the pigeon livers of Hangang Park, but not in the bones. In contrast, the 13 cases of 16 reviewed cases had the highest Zn concentration in bones, and the 3 cases in livers. In addition, the heavy metal distribution patterns in relations to the metal accumulation mechanisms (a competition between Pb and Ca, a function of methallothionein protein, and etc.) were discussed.