Blood lead levels of residents living around 350 abandoned metal mines in Korea

In 2007, as part of the control and prevention of environmental contamination threatening public health, the Korean Ministry of Environment planned to implement a national biomonitoring survey of three metals: lead, cadmium, and mercury in the blood of residents living near 350 abandoned metal mines known to be contaminated and as possible threats to the health of inhabitants. Thus, we investigated demographic and lifestyle variables and blood lead levels in residents living around the mines and compared them against those of control subjects. We measured the blood lead concentrations in 14,849 subjects (14,132 from nearby the 350 abandoned metal mines and 717 subjects from eight control areas). A questionnaire was provided to all subjects to determine gender, age, mining experience, period of time living in the vicinity of mines, smoking status, and personal perception of abandoned mines as a health risk. The geometric means (95% confidence intervals) of the blood lead levels of residents living around the abandoned metal mines and control areas were 3.017 (2.996-3.037 μg/dL) [female, 2.797 μg/dL (2.771-2.822 μg/dL); male, 3.330 μg/dL (3.298-3.363 μg/dL)] and 2.757 (2.677-2.837 μg/dL) [female, 2.604 μg/dL (2.506-2.700 μg/dL); male, 2.993 μg/dL (2.859-3.126 μg/dL)], respectively. Among residents of the mining areas, nonsmokers and residents who had no mining experience showed significantly lower mean blood lead levels than did smokers, past smokers, and those with mining experience. The mean blood lead concentrations of residents who expressed some concern about the abandoned mines were significantly higher than those of residents without concerns. The mean blood lead concentration of residents living around the abandoned mines was significantly higher than that of residents living in control areas as well as that of the general adult Korean population. We also confirmed that smoking is an important variable to consider, as it increases blood lead concentration.     

Antibiotic resistance and plasmid profiling of <Emphasis Type="Italic">Vibrio</Emphasis> spp. in tropical waters of Peninsular Malaysia

Vibrio species isolated from four different sampling stations in the west coast of Peninsular Malaysia were screened for their antimicrobial resistance and plasmid profiles. A total of 138 isolates belonging to 15 different species were identified. Vibrio campbellii, V. parahaemolyticus, V. harveyi, and V. tubiashii were found to predominance species at all stations. High incidence of erythromycin, ampicillin, and mecillinam resistance was observed among the Vibrio isolates. In contrast, resistance against aztreonam, cefepime, streptomycin, sulfamethoxazole, and sulfonamides was low. All the Vibrio isolates in this study were found to be susceptible to imipenem, norfloxacin, ofloxacin, chloramphenicol, trimethoprim/sulfamethoxazole, and oxytetracycline. Ninety-five percent of the Vibrio isolates were resistant to one or more different classes of antibiotic, and 20 different resistance antibiograms were identified. Thirty-two distinct plasmid profiles with molecular weight ranging from 2.2 to 24.8 kb were detected among the resistance isolates. This study showed that multidrug-resistant Vibrio spp. were common in the aquatic environments of west coast of Peninsular Malaysia.     

A moving target—incorporating knowledge of the spatial ecology of fish into the assessment and management of freshwater fish populations

Freshwater fish move vertically and horizontally through the aquatic landscape for a variety of reasons, such as to find and exploit patchy resources or to locate essential habitats (e.g., for spawning). Inherent challenges exist with the assessment of fish populations because they are moving targets. We submit that quantifying and describing the spatial ecology of fish and their habitat is an important component of freshwater fishery assessment and management. With a growing number of tools available for studying the spatial ecology of fishes (e.g., telemetry, population genetics, hydroacoustics, otolith microchemistry, stable isotope analysis), new knowledge can now be generated and incorporated into biological assessment and fishery management. For example, knowing when, where, and how to deploy assessment gears is essential to inform, refine, or calibrate assessment protocols. Such information is also useful for quantifying or avoiding bycatch of imperiled species. Knowledge of habitat connectivity and usage can identify critically important migration corridors and habitats and can be used to improve our understanding of variables that influence spatial structuring of fish populations. Similarly, demographic processes are partly driven by the behavior of fish and mediated by environmental drivers. Information on these processes is critical to the development and application of realistic population dynamics models. Collectively, biological assessment, when informed by knowledge of spatial ecology, can provide managers with the ability to understand how and when fish and their habitats may be exposed to different threats. Naturally, this knowledge helps to better evaluate or develop strategies to protect the long-term viability of fishery production. Failure to understand the spatial ecology of fishes and to incorporate spatiotemporal data can bias population assessments and forecasts and potentially lead to ineffective or counterproductive management actions.     

Antibiotic resistance profile of bacterial isolates from animal farming aquatic environments and meats in a peri-urban community in Daejeon, Korea

The increasing usage of antibiotics in the animal farming industry is an emerging worldwide problem contributing to the development of antibiotic resistance. The purpose of this work was to investigate the prevalence and antibiotic resistance profile of bacterial isolates collected from animal farming aquatic environments and meats in a peri-urban community in Daejeon, Korea. In an antibacterial susceptibility test, the bacterial isolates showed a high incidence of resistance (～26.04%) to cefazolin, tetracycline, gentamycin, norfloxacin, erythromycin and vancomycin. The results from a test for multiple antibiotic resistance indicated that the isolates were displaying an approximately 5-fold increase in the incidence of multiple antibiotic resistance to combinations of two different antibiotics compared to combinations of three or more antibiotics. Most of the isolates showed multi-antibiotic resistance, and the resistance patterns were similar among the sampling groups. Sequencing data analysis of 16S rRNA showed that most of the resistant isolates appeared to be dominated by the classes Betaproteobacteria and Gammaproteobacteria, including the genera Delftia, Burkholderia, Escherichia, Enterobacter, Acinetobacter, Shigella and Pseudomonas.     

Congener-specific accumulation and environmental risk assessment of polybrominated diphenyl ethers in diverse Korean sewage sludge types

Industrial, domestic wastewater, and livestock sludge samples were collected from 23 wastewater treatment plants in Korea and analyzed for polybrominated diphenyl ethers (PBDEs). The concentrations of Σ₁₉PBDE ranged from 4.01 to 10,400 ng/g dry weight. The average Σ₁₉PBDE concentrations in industrial, domestic wastewater, and livestock sludge were 1,560?±?3,610, 402?±?148, and 27.6?±?50.4 ng/g dry weight, respectively. The composition of PBDEs differed according to the type of sludge. Among the PBDE congeners, BDE 209 was dominant in all sludge samples. After BDE 209, relatively high levels were found for BDE 28 and 47 from industrial sludge, BDE 47 and 99 from domestic wastewater sludge, and BDE 206, 207, and 208 from livestock sludge. Using hierarchical cluster analysis, sludges were divided into three groups according to PBDE congener composition. A risk assessment of PBDEs in sludge used for soil amendment was carried out. Preliminary results indicated that the potential risk of soil exposed to PBDEs in sludge was relatively low.     

Toward a robust analytical method for separating trace levels of nano-materials in natural waters: cloud point extraction of nano-copper(II) oxide

Cloud point extraction (CPE) factors, namely Triton X-114 (TX-114) concentration, pH, ionic strength, incubation time, and temperature, were optimized for the separation of nano-sized copper(II) oxide (nCuO) in aqueous matrices. The kinetics of phase transfer was studied using UV–visible spectroscopy. From the highest separation rate, the most favorable conditions were observed with 0.2 %?w/v of TX-114, pH?=?9.0, ionic strength of 10 mM NaCl, and incubation at 40 °C for 60 min, yielding an extraction efficiency of 89.2?±?3.9 % and a preconcentration factor of 86. The aggregate size distribution confirmed the formation of very large nCuO–micelle assemblies (11.9 μm) under these conditions. The surface charge of nCuO was also diminished effectively. An extraction efficiency of 91 % was achieved with a mixture of TX-100 and TX-114 containing 30 wt.% of TX-100. Natural organic and particulate matters, represented by humic acid (30 mg/L) and micron-sized silica particles (50 mg/L), respectively, did not significantly reduce the CPE efficiency (<10 %). The recovery of copper(II) ions (20 mg/L) in the presence of humic acid was low (3–10 %). The spiked natural water samples were analyzed either directly or after CPE by inductively coupled plasma mass spectrometry following acid digestion/microwave irradiation. The results indicated the influence of matrix effects and their reduction by CPE. A delay between spiking nCuO and CPE may also influence the recovery of nCuO due to aggregation and dissolution. A detection limit of 0.04 μg Cu/L was achieved for nCuO.     

Aquatic biomonitoring of Giardia cysts and Cryptosporidium oocysts in peninsular Malaysia

An aquatic biomonitoring of Giardia cysts and Cryptosporidium oocysts in river water corresponding to five villages situated in three states in peninsular Malaysia was determined. There were 51.3 % (20/39) and 23.1 % (9/39) samples positive for Giardia and Cryptosporidium (oo)cysts, respectively. Overall mean concentration between villages for Giardia cysts ranged from 0.10 to 25.80 cysts/l whilst Cryptosporidium oocysts ranged from 0.10 to 0.90 oocysts/l. Detailed results of the river samples from five villages indicated that Kuala Pangsun 100 % (9/9), Kemensah 77.8 % (7/9), Pos Piah 33.3 % (3/9) and Paya Lebar 33.3 % (1/3) were contaminated with Giardia cysts whilst Cryptosporidium (oo)cysts were only detected in Kemensah (100 %; 9/9) and Kuala Pangsun (66.6 %; 6/9). However, the water samples from Bentong were all negative for these waterborne parasites. Samples were collected from lower point, midpoint and upper point. Midpoint refers to the section of the river where the studied communities are highly populated. Meanwhile, the position of the lower point is at least 2 km southward of the midpoint and upper point is at least 2 km northward of the midpoint. The highest mean concentration for (oo)cysts was found at the lower points [3.15?±?6.09 (oo)cysts/l], followed by midpoints [0.66?±?1.10 (oo)cysts/l] and upper points [0.66?±?0.92 (oo)cysts/l]. The mean concentration of Giardia cysts was highest at Kuala Pangsun (i.e. 5.97?±?7.0 cysts/l), followed by Kemensah (0.83?±?0.81 cysts/l), Pos Piah (0.20?±?0.35 cysts/l) and Paya Lebar (0.10?±?0.19 cysts/l). On the other hand, the mean concentration of Cryptosporidium oocysts was higher at Kemensah (0.31?±?0.19 cysts/l) compared to Kuala Pangsun (0.03?±?0.03cysts/l). All the physical and chemical parameters did not show significant correlation with both protozoa. In future, viability status and molecular characterisation of Giardia and Cryptosporidium should be applied to identify species and genotypes/subgenotypes for better understanding of the epidemiology of these waterborne parasites.     

Distribution features of biological hazardous pollutants in residential environments in Korea

This research has been conducted continuously since 2009 as part of a cohort of studies examining relationships between asthma and genetic factors, dietary habits, and environmental factors. Based on data from environmental research on house dust mites and endotoxins, which are widely known as pollutants in bedding that cause asthma in pregnant women and children, this work was conducted to obtain basic data that can be used in future cohort studies that analyze links between distribution of biological hazards and physical features of residential environments. The detection rates of house dust mite allergens, Der p1 and Der f1, were 52.7 and 86.5 %, respectively, indicating that Der f1 is a dominant species in domestic indoor environments. According to comparisons between concentrations of house dust mites and endotoxins in bedding of pregnant women and children, Der p1 and endotoxins showed significantly lower concentrations in bedding of pregnant women compared with those in bedding of children, whereas Der f1 showed no significant difference in concentration according to bedding.