Residual congener pattern of dioxins in human breast milk in southern Vietnam

This study evaluated residual congener patterns of dioxin/furan (=PCDD/DF) related to tactical herbicides aerially sprayed over the regions of southern Vietnam through Operation Ranch Hand. The study focused on Cam Chinh (CC) commune, Quang Tri province (an area sprayed with tactical herbicides), and the Cam Phuc (CP) commune, Ha Tinh province (a non-sprayed area). Breast milk samples for analysis were collected in September 2002 and July 2003 from lactating primiparous and multiparous mothers born after the war (<31 years old). We found the levels of each congener in the CC commune were higher than in the CP commune, and determined specificity in the PCDD/DF congener pattern in CC commune samples by cluster analysis. The congener pattern is characterized by higher (the hexa-, the hepta-, and the octa-) chlorinated PCDD/DFs; this appears to be the same profile as that presented by pentachlorophenol (PCP), rather than 2,4,5-trichlorophenoxy acid (2,4,5-T) contaminated with 2,3,7,8-TCDD. A GC/MS study in the 1970s detected the chlorophenols 2,4-di and 2,4,6-trichlorophenol in some Agent Orange samples, which contained, like PCP, a wide variety of PCDD/DF congeners. In this context, it may be expected that certain tactical herbicides contaminated with various chlorophenol impurities, have a unique congener pattern when compared with pure 2,4,5-T formulations.     

Biodegradation of Chitosan-Gellan and Poly(L-lysine)-Gellan Polyion Complex Fibers by Pure Cultures of Soil Filamentous Fungi

The degradation of two kinds of polyion complex (PIC) fibers, chitosan-gellan (CGF), and poly(L-lysine)-gellan (LGF) fibers, by seven species of soil filamentous fungi has been investigated. All of the pure-line soil filamentous fungi, Aspergillus oryzae, Penicillium caseicolum, P. citrinum, Mucor sp., Rhizopus sp., Curvularia sp., and Cladosporium sp. grew on the two fiber materials. Microscopic observation of the biodegradation processes revealed that P. caseicolum on the CGF and LGF grew, along with the accompanying collapse of the fiber matrices. In the biochemical oxygen-demand (BOD) test, the biodegradation of the LGF by P. caseicolum and Curvularia sp. exceeded 97% carbon dioxide generation and the biodegradation of the CGF by A. oryzae was 59%. These results might offer some clues to the applications of the PIC fibers as environmentally biodegradable materials.     

Simultaneous determination of 2-phenylbenzotriazole-type mutagens, PBTA-1 through -8, in river water by liquid chromatography-tandem mass spectrometry

We describe a method for the simultaneous determination of eight kinds of phenylbenzotriazole-type mutagens (PBTA-1, -2, -3, -4, -5, -6, -7 and -8) in river water based on liquid chromatography-tandem mass spectrometry (LC/MS/MS). The application of dopant-assisted atmospheric pressure photoionization (APPI) for the detection of the PBTAs was studied. The APPI technique provided higher PBTA signal intensities than those obtained with an electrospray ionization (ESI) source, and the APPI method was used for the determination of the PBTAs. A solid-phase extraction procedure was used for the extractions of PBTA-1 through -8 from river water. The procedure was rapid and the relative standard deviations were below 15%. The detection limits of PBTA-1 through -8 in river water using the proposed method were found to range from 0.04 to 0.5 ng L(-1) and PBTAs were successfully detected in river water at sub-ng L(-1) levels.     

Spatial Assessment of the Alder Tree in Kushiro Mire, Japan using Remotely Sensed Imagery – Effects of the Surrounding Land Use on Kushiro Mire

The relationship between alder (Alnus japonica) distribution and surrounding land use in Kushiro Mire was spatially assessed using remotely sensed imagery. From the result, it was found out that the expanding area of alder trees in Kushiro Mire was affected by the agricultural land area in the upper course of the river basin and flooding in the lower course of the river. The soil sediments flowing into the Kushiro Mire from the agricultural land resulted in heavy sedimentation that favors the growth of alder trees. Consequently, the number and density of alder trees has increased. The future distribution of alder trees was predicted based on the mechanism of expansion of the alder-tree area in Kushiro Mire, and it was found that large vegetation areas in Kushiro Mire will be changed to areas with alder trees.     

Salivary cortisol and cortisone levels,and breast milk dioxin concentrations in Vietnamese primiparas

There is a great deal of concern regarding the adverse effects of polychlorinated dibenzodioxins (PCDD) and polychlorinated dibenzofurans (PCDF) present in Agent Orange and other herbicides on Vietnam's population and ecosystems. The purpose of this study was to determine the effect of dioxin exposure on adrenal steroids in saliva, and dioxin levels in breast milk, of primiparas in an Agent Orange/dioxin hot-spot and a non-exposed area in Vietnam on the basis of epidemiological research. The subjects were 35 lactating women who had recently given birth to their first or second child. A further sub-study involved eight primiparas from each area. All subjects were aged between 20 and 30 years with infants aged between 4 and 16 weeks. The mean concentration of PCDD, PCDF, and PCDD?+?PCDF toxic equivalents (TEQ) in breast milk in the hot-spot area was significantly higher than in the non-exposed area. Cortisol and cortisone levels in the saliva of primiparas in the hot-spot area were also significantly higher than those in the non-exposed area. There was a significant negative correlation between cortisol and the cortisol/cortisone ratio and PCDD?+?PCDF and PCDF TEQ levels in the hot-spot area. Furthermore, the correlation between cortisol and cortisone and the PCDD + PCDF, PCDD, and PCDF TEQ in the combination of hot spot + non-exposed area was significant according to the curve (bell style). Our results suggest that Agent Orange/dioxin exposure still exerts a major influence on the salivary hormones of the Vietnamese population.     

Interfaces in Cross-Linked and Grafted Bacterial Cellulose/Poly(Lactic Acid) Resin Composites

This article presents approaches to maximize the mechanical performance of bacterial cellulose/poly(lactic acid) composites through chemical modification of the interface. This is achieved by both cross-linking the layered bacterial cellulose structure and by grafting maleic anhydride to the matrix material. Unmodified and glyoxalized bacterial cellulose (BC) networks have been embedded in poly(lactic acid) (PLA) resin and then in maleated resin using a compression molding method. The effect of these chemical modifications on the physical properties of these composites is reported. The tensile properties of the composites showed that Young??s moduli can be increased significantly when both BC networks and PLA were chemically modified. Interface consolidation between layers in BC networks has been achieved by glyoxalization. The effect of these modifications on both stress-transfer between the fibers and between the matrix and the fibers was quantified using Raman spectroscopy. Two competitive deformation mechanisms are identified; namely the mobility between BC layers, and between BC and PLA. The coupling strength of these interfaces could play a key role for optimization of these composites?? mechanical properties.     

Development of dioxin toxicity evaluation method in human milk by enzyme-linked immunosorbent assay--assay validation for human milk

In this study, the development of a toxicity evaluation method for dioxins in human milk by enzyme-linked immunosorbent assay (ELISA) was reported. A total of 17 human milk samples were tested by ELISA and by gas chromatography/mass spectrometry (GC/MS) to assess whether the ELISA performed on samples obtained from primiparas could be considered as reliable enough for identifying a dioxins contamination in human milk. The concept of toxicity equivalent quantity (TEQ) screening was validated by comparing TEQ values for a set of human milk samples to the ELISA responses predicted for those samples. A fairly good correlation (r=0.920) between immunoassay and GC/MS was achieved for human milk. This ELISA should be useful for biological samples monitoring.     

Detonation characteristics of ammonium nitrate and activated carbon mixtures

To better understand the detonation characteristics of ammonium nitrate (AN) and activated carbon (AC) mixtures, steel tube tests were carried out for AN/AC mixtures of various compositions and different forms of AN (powdered, prilled, phase stabilized and granular), and the detonation velocity was measured. The powdered AN/AC mixtures gave higher detonation velocities than the other AN forms. For all the AN/AC mixtures, the experimentally observed detonation velocities at each loading density were far below the theoretically predicted values calculated by the CHEETAH code based on thermohydrodynamics, exhibiting so-called non-ideal detonation. The lowest detonation velocity of powdered AN/AC mixtures was obtained as D=1.25 km/s for an AC content of 0.1 wt%. This was considered to be close to the critical condition for stable detonation.     

Leaching of phosphorus from incinerated sewage sludge ash by means of acid extraction followed by adsorption on orange waste gel

Ashes from sewage sludge incineration have a high phosphorus content, approximately 8% (W/W), which indicates a potential resource of the limiting nutrient. Incineration of sewage sludge with subsequent recovery of phosphorus is a relatively new sludge treatment technique. In this article, the leaching of phosphorus by using sulfuric acid as well as hydrochloric acid by means of several batch experiments was presented. At the same time a selective recovery of phosphorus by adsorption was also discussed. The e ects of acid concentration, temperature and time on extraction were studied. The phosphorus leaching increased with the increase in acid concentration and temperature. Kinetic studies showed that the complete leaching of phosphorus took place in less than 4 h. Selective adsorption of phosphorus by using orange waste gel provided a hint for recovery of this natural resource, which eventually could meet the ever-increasing requirement for phosphorus. The overall results indicated that the incinerated sewage sludge ash can be treated with acid to e ciently recover phosphorus and thus can be considered a potentially renewable source of phosphorus.