Blood lead concentration and exposure related factors in Korea from the National Environmental Health Survey (KoNEHS) II (2012-2014).

This study evaluated lead concentrations in blood and related factors among the South Korean population based on data from the Korea National Environmental Health Survey (KoNEHS) II (2012-2014) conducted by the National Institute of Environmental Research and the Ministry of Environment. Personal data were obtained from non-institutionalized civilian Korean individuals in an interview with trained community surveyors using a structured questionnaire (n = 6,455, aged 19 or older, mean age 49.7 years). The lead concentrations in whole blood were analyzed by atomic absorption spectrophotometry (AAS) with a Zeeman-effect-based background corrector. The precision and accuracy of the analytical methods were verified by internal and external quality controls (G-EQUAS, Germany). Statistical analysis was performed using weighted KoNEHS II data separated by sex, and the lead concentration was expressed as a geometric mean (GM). Multiple linear regression was performed using the SPSS 23.0 software package (SPSS Inc., Chicago, IL, USA). The total GM of lead concentrations was 19.5 µg/L. Lead concentrations increased with age and were higher in males (22.8 µg/L) than in females (16.6 µg/L). Smokers and drinkers had higher concentrations than non-smokers and non-drinkers of both sexes. People who used herbal medications had higher concentrations than those who did not among females. People of both sexes living in rural areas had higher lead concentrations than those in urban areas. Lead concentrations also varied with educational level, total family income, the type of water regularly consumed, and occupation. The average lead concentration of the general adult population in Korea has rapidly decreased over time from 45.8 µg/L (1999) to 19.45 µg/L (2012-2014); however, it remains higher than that of the United States, Germany, and Canada. The factors significantly related to lead concentration in South Korea were age, sex, smoking and alcohol drinking status, herbal medication usage by females, residential area, drinking water at home, and occupation. These factors could be used to improve occupational and environmental hygiene among the Korean population.

Association of current phthalate exposure with neurobehavioral development in a national sample.

BACKGROUND: Previous studies have indicated that phthalate exposure may influence the development of children, but the current data are limited, and controversy remains regarding the sex-specific and age-specific effects of phthalate exposure. METHODS: We investigated the sex- and age-specific associations of current phthalate exposure with neurobehavioral development scores in a nationally representative sample of 6-18-year-olds participating in the Korean Environmental Health Survey in Children and Adolescents (KorEHS-C). Neurobehavioral development was assessed using the Korean Child Behavior Checklist (CBCL, N=1723) and the Korean Attention Deficit Hyperactivity Disorder Rating Scale (ARS, N=867). We measured the concentrations of phthalate metabolites in urine samples using high-performance liquid chromatography tandem mass spectrometry. The associations between urine phthalate metabolite concentrations and neurobehavioral development were examined by survey regression analysis for complex sampling and penalized regression splines using a generalized additive model. RESULTS: Survey regression analysis revealed that a higher mono-n-butyl phthalate (MnBP) level was associated with social (ß=0.60; 95% confidence interval=0.15-1.05), thought (0.55; 0.08-1.03), and attention (0.68; 0.21-1.14) problems on the CBCL. A significant association was found between the MnBP level and the ARS hyperactivity subscale score (0.42; 0.05-0.58). Higher levels of MnBP (0.87; 0.20-1.54), mono-2-ethyl-5-oxohexyl phthalate (MEOHP, 0.61; 0.11-1.11) and mono-2-ethyl-5-hydroxyhexyl phthalate (MEHHP, 0.51; 0.04-0.97) were associated with an increase in thought problems among the girls. Among the younger children aged 6-11 years, significant positive associations between the MnBP (0.71; 0.09-1.33), MECPP (0.74, 0.14-1.34), MEOHP (0.65; 0.10-1.20), and MEHHP (0.71; 0.21-1.21) levels and social problems and between the MnBP (1.11; 0.37-1.84), MEOHP (0.64; 0.13-1.15), and MEHHP (0.66; 0.18-1.14) levels and attention problems were observed. The penalized regression splines for the age-specific relationships between the urinary MnBP, MEOHP, and MEHHP levels and social and attention problems exhibited positive supralinear relationships with downward curvature in the 6-11 year age group. In contrast, the score for social problems exhibited nearly linear relationships with these levels in the 12-18 year age group. CONCLUSIONS: In this national sample, increased phthalate exposure exhibited supralinear associations with social, thought and attention problems in children aged 6-11 years, who showed greater vulnerability to phthalate exposure. The results highlight the need for the environmental regulation of phthalate exposure in younger children, even at low dosages.

Decrease in the urine cotinine concentrations of Korean non-smokers between 2009 and 2011 following implementation of stricter smoking regulations.

This study aimed to determine if there was an association between the implementation of smoking regulation policies and the urine cotinine concentrations of Korean non-smokers. The subjects of this study were 4612 non-smoking Korean citizens (aged 19 or older) selected from the first stage of the Korean National Environmental Health Survey conducted by the National Institute of Environmental Research from 2009 to 2011. Cotinine concentrations in urine were measured by GC-MS (limit of detection: 0.05 ng/mL). Changes in the urine cotinine concentration were analyzed using a weighted general linear model and linear regression and values were shown as geometric mean (GM). The GM urine cotinine concentration decreased over time (2.92 ng/mL in 2009, 1.93 ng/mL in 2010, and 1.25 ng/mL in 2011). The total decrease in the subjects' urine cotinine concentration between 2009 and 2011 was 2.79 ng/mL, representing a relative decrease of 54.7%. The decrease in GM urine cotinine concentration in each subgroup ranged from 2.17 ng/mL to 3.29 ng/mL (relative decreases of 46.4% and 62.8%, respectively), with the largest absolute reductions in subjects in the following groups: females, aged 40-49 years, detached residence type, no alcohol consumption, employed, secondhand smoke exposure. All groups had negative regression coefficients, all of which were significant (p < 0.001). Our results provide indirect indicators of the effectiveness of smoking regulation policies including the revision of the National Health Promotion Act in Korea.

3D intra-stacked CoO/carbon nanocomposites welded by Ag nanoparticles for high-capacity, reversible lithium storage.

A wet-chemical, facile strategy is proposed for forming three-dimensional intra-structured nanocomposites to facilitate the development of high performance anodes for lithium ion batteries. The nanocomposites are composed of cobalt oxide nanoparticles, reduced graphene oxides, and Ag nanoparticles, and all the constituent materials are incorporated homogenously in a layer-by-layer structured geometry by a simple sono-chemical hybridizing process in a single, one-pot batch. Herein, it is revealed that the homogenously intra-stacked oxide, carbon, and metallic phases play critical roles in determining electrochemical performance (i.e. high capacity, rate capability, and cycling stability) of nanocomposite-based anodes, owing to the characteristic chemical/physical nature of constituent materials welded by partial melting of the metallic nanoparticles. In particular, by virtue of a characteristic role of a nano-Ag phase in suppressing the irreversible capacity, a critical drawback for metal oxide-based anodes, excellent capacities are demonstrated (983 and 770 mA h g(-1) at current densities of 100 and 2000 mA g(-1), respectively).

Superior lithium storage performance using sequentially stacked MnO2/reduced graphene oxide composite electrodes.

Hybrid nanostructures based on graphene and metal oxides hold great potential for use in high-performance electrode materials for next-generation lithium-ion batteries. Herein, a new strategy to fabricate sequentially stacked α-MnO2 /reduced graphene oxide composites driven by surface-charge-induced mutual electrostatic interactions is proposed. The resultant composite anode exhibits an excellent reversible charge/discharge capacity as high as 1100 mA h g(-1) without any traceable capacity fading, even after 100 cycles, which leads to a high rate capability electrode performance for lithium ion batteries. Thus, the proposed synthetic procedures guarantee a synergistic effect of multidimensional nanoscale media between one (metal oxide nanowire) and two dimensions (graphene sheet) for superior energy-storage electrodes.

Color tuning and thermal quenching of different sensitizer ion, Mn2+ or Ce3+, doped Ba2Mg(BO3)2:Eu2+ phosphor.

Ba2Mg(BO3)2:Eu2+ phosphors incorporated with two different sensitizers, Mn2+ or Ce3+, were prepared and their emission properties, especially for color purity and thermal stability, were investigated thoroughly. The overall emission property induced by the Eu2+ ion and the resultant thermal behavior were strongly dependent on the type of codoped sensitizer ions, Mn2+ or Ce3+. Intense red emission peaking at 620 nm was obtained upon 370 nm excitation of the Mn2+-sensitized phosphor and the resultant light-emitting diode lamps using the given phosphor exhibited a more reddish emission with chromaticity coordinates of (0.602, 0.340). Thus, we can meet the purpose of illuminating elements by designing the proper chemical composition of the Eu2+-activated Ba2Mg(BO3)2 phosphor using different sensitizers: a more reddish emitting Mn2+-sensitized one for backlight units and a bright yellow-emitting Ce3+-sensitized one for solid-state lightings.

Mesoporous silica-assisted carbon free Li2MnSiO4 cathode nanoparticles for high capacity Li rechargeable batteries.

Porous and spherical Li2MnSiO4 nanoparticles have been synthesized through a facile sol-gel route via a mesoporous silica template. Galvanostatic charge-discharge of the resultant Li2MnSiO4 cathode exhibits enhanced charge-discharge capacity relative to that of particles prepared by the conventional sol-gel process, up to 25% in discharge capacity, even without any particulate process such as milling with conductive agents. The standout electrochemical performance could be attributed to the unique high surface-to-volume ratio, porous geometry and improved accommodation of transformation strains during the electrochemical lithiation-delithiation process.

Thermally stable white-emitting single composition Na(Sr,Ba)PO4:Eu2+, Mn2+ phosphor for near-ultraviolet-pumped light-emitting diodes.

Eu(2+) and Mn(2+) codoped, white-emitting Na(Sr,Ba)PO(4) phosphors are prepared, and their emission properties, especially for thermal stability, are thoroughly investigated. The thermal quenching and Eu(2+)/Mn(2+) energy transfer efficiency are totally different in the ratio of alkaline earth metals in host composition, NaBaPO(4), Na(Sr(0.5)Ba(0.5))PO(4), and NaSrPO(4), respectively. Furthermore, by using near-ultraviolet light-emitting diodes (LEDs) and the corresponding Na(Sr(0.5)Ba(0.5))PO(4):Eu(2+), Mn(2+) phosphor as light converters, we demonstrate a bright and thermally stable white-emitting LED. The resultant LED exhibits a warm white light [~4900 K, CIE coordinates of (0.33, 0.31)] with excellent thermal and hydrolytic stabilities comparable to those of commercially available ones, Y(3)Al(5)O(12):Ce(3+) and BaMg(2)Al(16)O(27):Eu(2+). The proposed composition, with its efficient energy transfer, could enable Eu(2+) and Mn(2+) codoped Na(Sr,Ba)PO(4) to be a promising single component phosphor for cost-effective white-emitting LEDs.

Difference between proximal and distal microsatellite-unstable sporadic colorectal cancers: analysis of clinicopathological and molecular features and prognoses.

BACKGROUND: Distal microsatellite instability (MSI)-high colorectal cancers (CRCs) have been investigated by few studies and are generally regarded as having similar features to proximal MSI-high CRCs. In the present study, we aimed to elucidate whether distal sporadic MSI-high CRCs displayed distinguished clinicopathological and molecular features from proximal MSI-high CRCs. METHODS: All patients who underwent their first surgical resections for stage I-IV sporadic CRCs between August 2003 and August 2006 were initially considered for enrollment, and their MSI data were prospectively collected. Among them, 135 patients with MSI-high CRCs (86 proximal and 49 distal CRCs) were finally identified. The clinicopathological and molecular characteristics, and prognosis of these cases with MSI-high CRCs were reviewed and compared according to tumor site (proximal versus distal). RESULTS: Distal MSI-high CRCs showed significantly more frequent association with younger age, male gender, differentiated histology, small tumor size, distant metastasis, stability in BAT25 and BAT26, and hMLH1 expression on immunohistochemical staining as compared with proximal MSI-high CRCs. In addition, distal MSI-high CRCs demonstrated significantly worse 3-year overall and disease-free survival rates than proximal MSI-high CRCs (87.0% versus 97.4%; 81.6% versus 95.9%). For stage III-IV CRCs, distal MSI-high CRCs also showed significantly worse 3-year overall and disease-free survival rates than proximal MSI-high CRCs (72.2% vs. 90.5%; 58.3% vs. 94.4%). CONCLUSIONS: These results indicated that distal sporadic MSI-high CRCs formed a distinct subgroup with distinguished clinicopathological and molecular features from proximal MSI-high CRCs. In addition, this study demonstrated that distal MSI-high CRCs had worse prognosis than proximal MSI-high CRCs.

Long-term outcome of preoperative transarterial chemoembolization and hepatic resection in patients with hepatocellular carcinoma.

BACKGROUND/AIMS: Transarterial chemoembolization (TACE) improves the survival of patients with unresectable hepatocellular carcinoma (HCC) and has been recommended as a first-line therapy for nonsurgical patients with large or multifocal HCC. The long-term outcome of HCC patients receiving TACE prior to hepatic resection is uncertain. METHODS: Between January 1997 and December 2007, 1,530 patients underwent hepatic resection for HCC at our center. Thirty-two patients received 1~12 sessions of TACE followed by surgical resection (TACE-surgery group). Their overall and recurrence-free survival rates were compared with those of 64 age- and sex-matched controls who underwent surgery only (surgery group). Overall and recurrence-free survival rates were analyzed. RESULTS: The 1-, 2-, and 5-year overall survival rates did not differ significantly between the TACE-surgery group and the surgery group (78%, 60%, and 26%, respectively, vs. 97%, 83%, and 45%, respectively; P=0.11); however, the 1-, 2-, and 5-year recurrence-free survival rates were significantly lower in the TACE-surgery group than in the surgery group (58%, 36%, and 7%, respectively, vs. 77%, 58%, and 32%, respectively; P=0.01). The distribution of recurrence sites in the TACE-surgery group were intrahepatic in 85.7% and extrahepatic in 14.3%, and did not differ from those in the surgery group (91.4% and 8.6%, respectively; P=0.66). CONCLUSIONS: HCC patients who underwent TACE before resection appear to have overall survival rates that are comparable to those without preoperative therapy, although recurrence rates appear to be higher in patients with TACE.

Sporadic colorectal carcinomas with low-level microsatellite instability in Korea: do they form a distinct subgroup with distinguished clinicopathological features?

BACKGROUND: The biologic significance of low-level microsatellite instability (MSI) in colorectal cancers (CRCs) remains unclear. This study aimed to elucidate whether sporadic MSI-low CRCs in Korea displayed distinguished clinicopathological characteristics from microsatellite stable (MSS) and MSI-high CRCs. METHODS: We consecutively enrolled 657 patients who underwent their first surgical resections for stage I-IV sporadic CRCs and compared their clinicopathological features and prognosis after resection according to MSI status (574 MSS, 30 MSI-low and 53 MSI-high CRCs). RESULTS: When compared with MSS CRCs, MSI-low CRCs showed significantly more frequent association with poorly differentiated histology, mucinous carcinoma, and large tumour size. In addition, MSI-low CRCs demonstrated significantly less frequent lymph node metastasis and advanced tumour stage than MSS CRCs. When compared with MSI-high CRCs, MSI-low CRCs were significantly more frequently located in distal colon. Three-year overall and disease-free survival rates of MSS, MSI-low and MSI-high CRCs were 83.5%, 90.0% and 91.7% and 82.0%, 89.1% and 87.5%, respectively and neither demonstrated significant difference between three groups. CONCLUSIONS: These results indicated that sporadic MSI-low CRCs in Korea displayed distinguished clinicopathological features and might form a distinct subgroup especially from MSS CRCs. Further large studies are required to evaluate the impact of MSI-low status on prognosis.

Prediction of complete necrosis of hepatocellular carcinoma treated with transarterial chemoembolization prior to liver transplantation.

BACKGROUND/AIMS: Compact lipiodol uptake without enhancement on multiphasic helical computed tomography (CT) has been suggested as a radiologic response criterion in hepatocellular carcinoma (HCC) patients treated with transarterial chemoembolization (TACE) and subsequent partial hepatectomy. However, its usefulness has not been fully investigated in the explanted liver. METHODS: Between 1998 and 2007, 81 patients with HCC underwent 1-9 sessions of TACE followed by liver transplantation (LT). Thirty-nine tumors in 29 patients showed a radiologic response on CT performed prior to LT. The radiologic response criteria and the duration of the response were evaluated to predict total necrosis in the explanted liver. RESULTS: Among the 39 tumors, 34 nodules (87.2%) exhibited total pathological necrosis. While 13 out of 16 tumors (81.3%) with a radiologic response for 6 months or less were completely necrotic, 21 out of 23 tumors (91.3%) with a radiologic response of longer than 6 months showed total necrosis. CONCLUSIONS: Our results suggested that the radiologic response criteria based on serial CT images might be useful for predicting total necrosis of TACE-pretreated HCC in LT.