Kang C.S.,KEPCO E&C |
Lee J.-H.,NeoEnBiz Co. |
Kim S.-K.,NeoEnBiz Co. |
Kim S.-K.,Seoul National University |
And 10 more authors.
Chemosphere | Year: 2010
Fetal and maternal exposure levels of two emerging pollutants, polybrominated diephenyl ethers (PBDEs) and synthetic musks, were measured in Korean general population to assess prenatal and postnatal exposures in infants. For this purpose, paired samples of breast milk, maternal and cord blood were collected from 20 Korean women in 2007. In comparison to data from other countries and previous data from Korea, relatively higher and gradually increasing concentrations for PBDEs were found in Korean breast milk (
Kim S.-K.,Seoul National University |
Lee K.T.,NeoEnBiz Co. |
Kang C.S.,KEPCO E&C |
Tao L.,New York State Department of Health |
And 9 more authors.
Environmental Pollution | Year: 2011
The levels of six perfluorocarboxylates (PFCAs), four perfloroalkylsulfonates (PFASs), and one sulfonamide were measured in paired samples of maternal serum, umbilical cord serum, and breast milk. The maternal and cord sera were strongly correlated with each other for all measured compounds (r > 0.5 and p < 0.01). Nevertheless, there was a significant difference in compound composition profile between the two sera matrices, with a more depletion of the longer chain compounds in cord serum. The transfer efficiency values from maternal to cord serum (TFCS/MS) decreased by 70% with each increasing unit of -CF2 chain within a PFCA group, and for perfluorooctanesulfonate (PFOS), by a half compared to perfluorooctanoate (PFOA). In contrast to the strong correlation in concentrations between the two sera matrices, the pattern of compounds in breast milk differed considerably with those in sera. Accordingly, compound- and matrix-specific transfer must be considered when assessing prenatal and postnatal exposure. © 2010 Elsevier Ltd. All rights reserved.
PubMed | NeoEnBiz Co., Ulsan National Institute of Science and Technology and Seoul National University
Type: Journal Article | Journal: Marine pollution bulletin | Year: 2016
Water, suspended particulate matter (SPM), and biota samples were collected from the Taehwa River Estuary to determine the distributions, partitioning, and bioaccumulation of arsenicals. Six forms of As were quantitated by the use of HPLC-ICP/MS. As was found mainly near urban and industrial areas, and inorganic As(V) was the predominant As form in both water and SPM. Particulate arsenicals were found at the greatest concentrations in coarse particles (>180m), followed by medium (30-180m) and fine (0.45-30m) particles, in freshwater. Arsenical concentrations were similar across the three particle fractions in saltwater. Field-based distribution coefficient (Kd) values for As depended strongly on SPM, with a less robust dependence on salinity. Concentrations of As were greater in macroalgae than in marine animals, such as fishes, bivalves, crabs, shrimps, and gastropods. Overall, the results of the present study provide useful information on the behaviors and fate of arsenicals in an estuarine environment.
PubMed | National Institute of Environmental Research NIER, NeoEnBiz Co. and Gwangju Institute of Science and Technology
Type: Journal Article | Journal: Environmental pollution (Barking, Essex : 1987) | Year: 2015
The aim of this study was to identify how hydrologic factors (e.g., rainfall, maximum depth, reservoir and catchment area, and water residence time) and water chemistry factors (e.g., conductivity, pH, suspended particulate matter, chlorophyll-a, dissolved organic carbon, and sulfate) interact to affect the spatial variance in monomethylmercury (MMHg) concentration in nine artificial reservoirs. We hypothesized that the MMHg concentration of reservoir water would be higher in eutrophic than in oligotrophic reservoirs because increased dissolved organic matter and sulfate in eutrophic reservoirs can promote in situ production of MMHg. Multiple tools, including Pearson correlation, a self-organizing map, and principal component analysis, were applied in the statistical modeling of Hg species. The results showed that rainfall amount and hydraulic residence time best explained the variance of dissolved Hg and dissolved MMHg in reservoir water. High precipitation events and residence time may mobilize Hg and MMHg in the catchment and reservoir sediment, respectively. On the contrary, algal biomass was a key predictor of the variance of the percentage fraction of unfiltered MMHg over unfiltered Hg (%MMHg). The creation of suboxic conditions and the supply of sulfate subsequent to the algal decomposition seemed to support enhanced %MMHg in the bloom reservoirs. Thus, the nutrient supply should be carefully managed to limit increases in the %MMHg/Hg of temperate reservoirs.
Lee K.T.,NeoEnBiz Co |
Hong S.,Seoul National University |
Lee J.S.,NeoEnBiz Co |
Chung K.H.,Sungkyunkwan University |
And 7 more authors.
Environmental Science and Pollution Research | Year: 2013
While the World Health Organization 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalency factors are useful estimates of relative potencies of mixtures when conducting risk assessments, they are not useful when comparing the results of bioassays such as the H4IIE-luc to concentrations of TCDD equivalents calculated from instrumental analyses. Since there are thousands of dioxin-like compounds (DLCs), one use of screening assays is to determine if all of the aryl hydrocarbon receptor (AhR) active DLCs in a mixture have been accounted for in instrumental analyses. For this purpose, bioassay-specific relative potency (ReP) values are needed. RePs of 21 polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and dioxin-like polychlorinated biphenyls that exhibit effects mediated through the AhR were determined by use of the H4IIE-luc assay. Different values of RePs are derived, depending on the statistical, curve-fitting methods used to derive them from the dose-response relationships. Here, we discuss the various methods for deriving RePs from in vitro data and their assumptions and effects on values of RePs. Full dose-response curves of 2,3,7,8-TCDD and other representative DLCs were used to estimate effective concentrations at multiple points (e.g., EC20-50-80), which were then used to estimate ReP of each DLC to 2,3,7,8-TCDD. © 2013 Springer-Verlag Berlin Heidelberg.
Lee C.-H.,NeoEnBiz Co. |
Lee J.-H.,NeoEnBiz Co. |
Sung C.-G.,NeoEnBiz Co. |
Sung C.-G.,University of Seoul |
And 6 more authors.
Marine Pollution Bulletin | Year: 2013
Ecotoxicological monitoring of intertidal sediments was performed for 5. years after the Hebei Spirit oil spill in Taean, Korea. Sediment toxicity was observed on most of the beaches 4. months after the spill and later decreased rapidly to nontoxic levels 8. months after the spill. The concentrations of total polycyclic aromatic hydrocarbons (TPAHs) in the sediments ranged from 2 to 530,000. ng/g during the monitoring. More than half of the samples exhibited significant toxicity 5. years after the Hebei Spirit oil spill. Using a logistic regression model, the median lethal concentration of TPAHs to amphipod Monocorophium uenoi was estimated to be 36,000. ng/g. From the 63 chemistry and toxicity data, the effect range-low, effect range median, threshold effect level, and probable effect level were derived to be 3190, 54,100, 2480, and 29,000. ng/g, respectively. The relative compositions of the PAH groups indicated that the weathering process is still ongoing. © 2013 Elsevier Ltd.
Kim H.-S.,Sungkyunkwan University |
Park J.-W.,Sungkyunkwan University |
Park S.-M.,Sungkyunkwan University |
Lee J.-S.,Neoenbiz Co. |
Lee Y.-Z.,Sungkyunkwan University
Wear | Year: 2013
In order to develop an eco-friendly lubricant, nanodiamonds were selected and added to a paraffin liquid by a matrix synthesis method. This method can maintain good dispersibility without cohesion and avoid precipitation for an extended period of time. The lubricity of dispersed oils with different amounts of nanodiamond particles was compared using both constant load and step loading on ball-on-disk type tests. Friction characteristics, wear amount, and scuffing life were determined. During the tests, the temperatures of oils were monitored in order to verify the heat dispersion rates of oils that contained nanodiamond. Several hypotheses are presented to explain the results of this work. By the addition of nanodiamond particles, the coefficient of friction may have been reduced due to their octagonal, almost spherical shape which can act as rolling contact elements between two surfaces. Also, it is proposed that nanodiamond can support the load between two sliding surfaces because of its high hardness value. Because the nanodiamond has the ability to disperse the generated frictional heat, it leads to increase the scuffing life. © 2013 Elsevier B.V.
PubMed | Korea University, Seoul National University, Asian Citizens Center for Environment and Health, Korea Institute of Toxicology and 7 more.
Type: Journal Article | Journal: Indoor air | Year: 2015
We conducted a comprehensive humidifier disinfectant exposure characterization for 374 subjects with lung disease who presumed their disease was related to humidifier disinfectant use (patient group) and for 303 of their family members (family group) for an ongoing epidemiological study. We visited the homes of the registered patients to investigate disinfectant use characteristics. Probability of exposure to disinfectants was determined from the questionnaire and supporting evidence from photographs demonstrating the use of humidifier disinfectant, disinfectant purchase receipts, any residual disinfectant, and the consistency of their statements. Exposure duration was estimated as cumulative disinfectant use hours from the questionnaire. Airborne disinfectant exposure intensity (g/m(3)) was estimated based on the disinfectant volume (ml) and frequency added to the humidifier per day, disinfectant bulk level (g/ml), the volume of the room (m(3)) with humidifier disinfectant, and the degree of ventilation. Overall, the distribution patterns of the intensity, duration, and cumulative exposure to humidifier disinfectants for the patient group were higher than those of the family group, especially for pregnant women and patients 6 years old. Further study is underway to evaluate the association between the disinfectant exposures estimated here with clinically diagnosed lung disease.Retrospective exposure to household humidifier disinfectant as estimated here can be used to evaluate associations with clinically diagnosed lung disease due to the use of humidifier disinfectant in Korea. The framework, with modifications to account for dispersion and use patterns, can also be potentially adapted to assessment of other household chemical exposures.
Kim C.-K.,NeoEnBiz Co |
Kim C.-K.,Seoul National University |
Lee T.-W.,NeoEnBiz Co |
Lee K.-T.,NeoEnBiz Co |
And 2 more authors.
Chemosphere | Year: 2012
Mercury (Hg) concentrations were monitored in wild and cultured fish collected from fresh and coastal waters in the Korean peninsula from April 2006 to August 2008 nationwide. Total Hg concentrations were reported for 5043 fish samples, including 78 species from 133 locations. Significant interspecies variation was noted in the Hg levels. The average Hg concentration in each fish species ranged from 6.31μgkg-1 for mullet (Mugil cephalus) to 200μgkg-1 for mandarin fish (Siniperca scherzeri). Among the species collected, the maximum concentration of Hg, 1720μgkg-1, was measured in an Amur catfish (Silurus asotus). Only wild freshwater fish exceeded the WHO ingestion standard. Wild freshwater piscivorous fish samples from a large artificial upstream lake contained the highest Hg levels. Hg concentrations were compared between fish groups categorized as wild and farmed fish from freshwater and coastal waters. Although the wild freshwater fish had similar size ranges, their Hg concentrations were higher than those of the other groups. Compared to the feed of farmed marine and freshwater fishes, the prey of wild freshwater fish had a higher Hg concentration, and the total Hg concentrations in freshwater and associated sediment samples were higher than those in coastal water and associated sediment samples. In the freshwater environment, piscivorous fish bioaccumulated two times more Hg than carnivorous and omnivorous fish and four times more than planktivorous fish. The difference in Hg concentrations among trophic groups might have been due to differences in the size of fish, in addition to the variations among different trophic groups. These data will be useful for developing the fish consumption advisory as a management measure to reduce Hg exposure. © 2012 Elsevier Ltd.
PubMed | University of Hong Kong, NeoEnBiz Co. and Seoul National University
Type: | Journal: Environmental pollution (Barking, Essex : 1987) | Year: 2016
Effect-directed analysis (EDA) was performed to identify the major aryl hydrocarbon receptor (AhR) agonists in sediments collected from a highly industrialized area (Lake Shihwa, Korea). Great AhR-mediated potencies were found in fractions containing aromatic compounds with log Kow values of 5-8, and relatively great concentrations of styrene oligomers (SOs) and polycyclic aromatic hydrocarbons (PAHs) were detected in those fractions. Until now, there was little information on occurrences and toxic relative potencies (RePs) of SOs in coastal environments. In the present study; i) distributions and compositions, ii) AhR binding affinities, and iii) contributions of SOs to total AhR-mediated potencies were determined in coastal sediments. Elevated concentrations of 10 SOs were detected in sediments of inland creeks ranging from 61 to 740ngg(-1) dry mass (dm), while lesser concentrations were found in inner (mean=33ngg(-1)dm) and outer regions (mean=25ngg(-1)dm) of the lake. Concentrations of PAHs in sediments were comparable to those of SOs. 2,4-diphenyl-1-butene (SD3) was the predominant SO analogue in sediments. SOs and PAHs were accumulated in sediments near sources, and could not be transported to remote regions due to their hydrophobicity. RePs of 3 SOs could be derived, which were 1000- to 10,000-fold less than that of one representative potent AhR active PAH, benzo[a]pyrene. Although concentrations of SOs in sediments were comparable to those of PAHs, the collective contribution of SOs to total AhR-mediated potencies were rather small (<1%), primarily due to their smaller RePs. Overall, the present study provides information on distributions and AhR binding affinities for SOs as baseline data for degradation products of polystyrene plastic in the coastal environment.