Assessment of organochlorine pesticides in the atmosphere of South Korea: spatial distribution, seasonal variation, and sources.

Organochlorine pesticides (OCPs) are widely used in certain countries. We determined atmospheric concentrations, distribution patterns, and seasonal variations of OCPs at four sites in South Korea for 1 year. Samples of 22 OCPs were collected using a high-volume air sampler, and measured via the isotope dilution method with HRGC/HRMS. In South Korea, pentachlorobenzene (PeCB), hexachlorocyclohexane (HCB), and endosulfan (EnSF) were dominant, accounting for > 87% of total OCPs. Spatial distributions showed significant differences and the highest levels were observed in Seosan (295.2 pg·m-3), indicating the compounding potential of diverse sources as Seosan has concentrated large-scale industrial complexes and agricultural activity (Seoul: 243.6 pg·m-3 > Jeju: 193.5 pg·m-3 > Baengnyeong: 178.2 pg·m-3). The isomeric ratios of OCPs in the South Korean atmosphere indicated that the dominant sources of HCB and dichlorodiphenyltrichloroethane were primarily used in the past; meanwhile, chlordane (CHL) and EnSFs were derived from recent material inputs. Seasonally, OCP concentrations largely peaked in summer with minimum values in winter. This apparent temperature dependence suggests the re-volatilization of accumulated chemicals into the atmosphere. Additionally, an air mass back trajectory indicated the influence of pollutants released from a reservoir through long-range atmospheric transport in the summer. In particular, restricted OCPs are primarily released into the atmosphere by inadvertent sources, such as industrial activities and volatilization from contaminated areas. Thus, severe OCP pollution in Korea is due to the mobile nature of the particles. These data can be useful for the continuous monitoring of long-range transported air pollutants that are transferred between countries.

Nontarget screening using passive air and water sampling with a level II fugacity model to identify unregulated environmental contaminants.

It is thought that there are many unregulated anthropogenic chemicals in the environment. For risk assessment of chemicals, it is essential to estimate the predicted environmental concentrations. As an effort of identifying residual organic contaminants in air and water in Korea, nontarget screening using two-dimensional gas chromatography time-of-flight mass spectrometry (GC×GC-TOFMS) was conducted at 10 sites using polyurethane foam passive air sampler and at 6 sites using polydimethyl siloxane (PDMS) passive water sampler in three different seasons in 2014. More than 600 chemical peaks were identified satisfying the identification criteria in air and water samples, respectively, providing a list for further investigation. Chemical substances with reported national emission rates in 2014 (n=149) were also screened for potential existence in the environment using a level II fugacity model. Most of chemical substances classified as not detectable were not identified with detection frequency greater than 20% by nontarget screening, indicating that a simple equilibrium model has a strong potential to be used to exclude chemicals that are not likely to remain in the environment after emissions from targeted monitoring.

Ring-expansion protocol: preparation of synthetically versatile dihydrotropones.

A ring-expansion protocol that consisted of the 1,2-addition of various enolate nucleophiles to 6-trimethylsiloxy-2-cyclohexene-1-one (1) and the NaIO(4)-promoted oxidative ring opening of the resulting diols 2, followed by an intramolecular Knoevenagel condensation, furnished versatile dihydrotropones 6. Maintaining Z-configuration in the oxidative ring-opening products 3 is crucial for the success of the ring-expansion strategy. Dihydrotropones 6 are ripe for further elaborations such as oxidation to tropones 8 and Diels-Alder reaction with the Danishefsky's diene 10 to afford polycyclic compounds 12.

Predicting factors for refractory kawasaki disease.

BACKGROUND AND OBJECTIVES: About 10-15% of Kawasaki disease (KD) is refractory to intravenous immunoglobulin (IVIG) therapy. This study was designed to investigate the predicting factors for refractory KD. SUBJECTS AND METHODS: We reviewed retrospectively the clinical records of 77 patients with typical KD admitted at Wonju Christian Hospital from January, 2005, to December, 2008. The variance of laboratory and demographic parameters between the IVIG-responsive group and IVIG-resistant group were analyzed. Thirteen patients with urinary tract infections were randomly collected as a febrile control group. RESULTS: Among 77 patients diagnosed with complete KD, 13 patients (16.9%) were IVIG-resistant. The febrile period and hospital days were significantly longer in the IVIG-resistant group than IVIG-responsive group (p<0.001, p=0.002). Serum levels of albumin and sodium were significantly lower in the IVIG-resistant group (p=0.025). The Kobayashi score could differentiate these two groups (p=0.015). Fewer lymphocytes was observed during the subacute phase in the IVIG-resistant group (p=0.032). Coronary arterial dilatations (CADs) were observed in 10.9% (7/64) of IVIG-responders and 38.5% (5/13) of IVIG-resistant patients (p=0.038). CONCLUSION: The percentage of neutrophils and lymphocytes in patients with KD, in addition to known risk factors for refractory KD, may help predict IVIG-resistance in patients with KD.