Effects of dissolved organic matter on toxicity and bioavailability of copper for lettuce sprouts

It is well known that dissolved organic matter in soil solution may affect the toxicity or bioavailability of heavy metals to plants, but existing information on various organic substances is insufficient for treating problems with heavy metal-contaminated soils. To clarify how dissolved organic matter alters the toxicity and bioavailability of metals, we germinated lettuce seeds exposed to solutions containing Cu and several kinds of dissolved organic matters. Low molecular weight organic acids (citric, malic, and oxalic acids) increased the toxicity and bioavailability of Cu, but low concentrations of the synthetic chelators ethylenediamine tetra-acetic acid (EDTA) and diethylenetriamine penta-acetic acid (DTPA) decreased the toxicity and bioavailability of Cu. In contrast, humic acid appeared to be the most effective organic substance for detoxifying Cu, even though it did not significantly decrease the bioavailability of Cu. Consequently, the bioavailability and toxic effects of Cu in soil depend on the nature of coexisting organic substances in the soil solution.     

Novel malonate-type copolymers containing vinyl alcohol blocks as biodegradable segments and their builder performance in detergent formulations

Poly[(disodium methylene malonate)-co-(vinyl alcohol)] [P(DSMM-VA)] and poly[(disodium ethoxymethylene malonate)-co-(vinyl alcohol)] [P(DSEMM-VA)] containing a poly(vinyl alcohol) (PVA) block as a biodegradable segment were prepared and their biodegradability and functionality were evaluated and compared with those of the corresponding fumarate and maleate copolymers. It was found that the 1,1-dicarboxylate-type copolymers, P(DSMM-VA) and P(DSEMM-VA), showed better biodegradability than the corresponding 1,2-dicarboxylate-type copolymers, P(DSF-VA) and P(DSM-VA). This improved biodegradability of P(DSMM-VA) and P(DSEMM-VA) is probably attributable to their more expanded polymer chain in aqueous solution, which will be more accessible to the degrading enzymes. The minimum chain length of the PVA-block, which acts as a biodegradable segment in the polymer chain, is estimated to be 2–3 and 3–4 monomer units for P(DSMM-VA) and P(DSEMM-VA), respectively. On the other hand, the minimum PVA block is about 5 and 7 monomer units for the fumarate and maleate copolymers, respectively. It was confirmed that P(DSMM-VA) showed excellent builder performance compared to the corresponding fumarate copolymer.Paper presented at the Bio/Environmentally Degradable Polymer Society—Second National Meeting, August 19–21, 1993, Chicago, Illinois.     

Effect of in vitro administered 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on DNA-binding activities of nuclear transcription factors in NIH-3T3 mouse fibroblasts

Abstract

Most modern pesticides are expensive. Application of excessive dosage rates is likely to cause undesirable biological side‐effects and is economically wasteful. Non‐uniform distribution of the spray cloud, or application at the wrong time, may result in failure to control the pest. It is the responsibility of the field operator to acquire sufficient knowledge and skill to ensure proper use of the control agents, to increase efficiency of their usage and to reduce unwanted side‐effects. To achieve this goal, he must take into consideration the various physical factors that govern field performance of pesticides.

A simple relationship exists between the spray volume and emission rate used, and droplet size produced. The use of extremely low spray volumes (i.e., those less than 2.0 litre per ha) for forest insect control in Canada, as opposed to higher volumes used in agriculture, necessitates the release of fine droplets (ranging from 20 to 70 μm in diameter) to obtain adequate coverage of the target area. These droplets take a long time to sediment downwards, evaporate in‐flight, become smaller in size and/or form powdery residues, thus contributing to off‐target drift and impaired droplet adhesion to target surfaces. Physical factors such as rain washing, degradation by sunlight and erosion by wind also influence the longevity of pesticide deposits on foliage which is crucial during the critical period of pest control.

Factors affecting the mode of entry into insects are related to the type of ingredients used in formulation. If a pesticide acts via crawling contact, formulations which would provide surface deposits would be more beneficial than emulsions or oil‐based mixes which tend to undergo penetration into foliar cuticle. Physical factors that affect field performance of a pesticide tank mix are related to phase separation and ‘breakdown of emulsions’ in the application equipment; ‘agglomeration and caking’ of wettable powder dispersions at the bottom of the tank; impaired flow behaviour of highly viscous formulations; and coarse atomization of high‐viscosity tank mixes leading to poor target cover.     

High affinity binding of 3H‐verapamil to rat brain synaptic membrane is antagonized by pyrethroid insecticides

Abstract

Deltamethrin is a powerful neuroactive agent causing increased neurotransmitter release at the synapse. To understand the cause for such an action of this pyrethroid insecticide, we have studied its binding characteristics to the calcium channel by utilizing ³H‐verapamil as a specific ligand. It was found that deltamethrin is capable of competing at the same binding site as ³H‐verapamil. Also, it was found that nonlabeled verapamil could reduce the binding of ³H‐deltamethrin (tested at 1 nM) to its binding site. The EC₅₀ value of verapamil to displace 50% of ³H‐deltamethrin was in the order of 0.3 μM, which coincides with the approximate K_D value for this ligand to bind with calcium channels in the rat brain synaptosomal plasma membranes.     

Association of serum levels of polychlorinated biphenyls with IL-8 mRNA expression in blood samples from asthmatic and non-asthmatic Japanese children

Background

One of the suggested health outcomes of PCB exposure is childhood asthma.

Objectives

This study was conducted to find health relevant biomarkers providing the molecular epidemiological evidence for the positive relationship between exposure to PCBs and childhood asthma.

Methods

Blood samples from fifteen asthmatic children as well as an equal number of non-asthmatic children (average 2 year old) were collected, and were analyzed for PCBs and their select marker expression by using qRT-PCR.

Results

Among biomarkers examined IL-8 expression was significantly correlated to serum levels of PCB #163 + 164 (P = 0.022), #170 (P = 0.046), #177 (P = 0.022), #178 (P = 0.022) and #180 + 193 (P = 0.046) in a dose-dependent manner, which was found only among asthmatic children. In contrast, COX-2 correlations to individual congener levels were recognized only among control subjects, not among asthmatic subjects.

Conclusion

Serum concentrations of PCB#163 + 164, #170, #177, #178 and #180 + 193 correlate significantly with IL-8 mRNA expressions among asthmatic children.     

Monitoring OH-PCBs in PCB transport worker’s urine as a non-invasive exposure assessment tool

In this study, we analyzed hydroxylated polychlorinated biphenyls (OH-PCBs) in urine of both PCB transport workers and PCB researchers. A method to monitor OH-PCB in urine was developed. Urine was solid-phase extracted with 0.1% ammonia/ methanol (v/v) and glucuronic acid/sulfate conjugates and then decomposed using β-glucuronidase/arylsulfatase. After alkaline digestion/derivatization, the concentration of OH-PCBs was determined by HRGC/HRMS-SIM. In the first sampling campaign, the worker’s OH-PCB levels increased several fold after the PCB waste transportation work, indicating exposure to PCBs. The concentration of OH-PCBs in PCB transport workers’ urine (0.55~11 μg/g creatinine (Cre)) was higher than in PCB researchers’ urine (< 0.20 μg/g Cre). However, also a slight increase of OH-PCBs was observed in the researchers doing the air sampling at PCB storage area. In the second sampling, after recommended PCB exposure reduction measures had been enacted, the worker’s PCB levels did not increase during handling of PCB equipment. This suggests that applied safety measures improved the situation. Hydroxylated trichlorobiphenyls (OH-TrCBs) were identified as a major homolog of OH-PCBs in urine. Also, hydroxylated tetrachlorobiphenyls (OH-TeCBs) to hydroxylated hexachlorobiphenyls (OH-HxCBs) were detected. For the sum of ten selected major indicators, a strong correlation to total OH-PCBs were found and these can possibly be used as non-invasive biomarkers of PCB exposure in workers managing PCB capacitors and transformer oils. We suggest that monitoring of OH-PCBs in PCB management projects could be considered a non-invasive way to detect exposure. It could also be used as a tool to assess and improve PCB management. This is highly relevant considering the fact that in the next 10 years, approx. 14 million tons of PCB waste need to be managed. Also, the selected populations could be screened to assess whether exposure at work, school, or home has taken place.     

Mapping the global supply and demand structure of rice

Rice plays a major role in the global supply and demand for sustainable food production. The constraints of maintaining sustainable rice production are closely linked to the relationship between the distribution patterns of human activity on the planet and economic growth. Global patterns of rice production can be mapped by using various criteria linked to domestic income, population patterns, and associated satellite brightness data of rice-producing regions. Prosperous regions have more electric lighting, and there are documented correlations between gross domestic product (GDP) and nighttime light. We chose to examine global rice production patterns on a geographical basis. For the purposes of this study, each country is considered to be made up of regions, and rice production is discussed in terms of regional distribution. A region is delineated by its administrative boundaries; the number of regions where rice is produced is about 13,839. We used gridded spatial population distribution data overlain by nocturnal light imagery derived from satellite imagery. The resultant relationship revealed a correlation between regional income (nominal values of GDP were used) and rice production in the world. The following criteria were used to examine the supply and demand structure of rice. Global rice consumption = “caloric rice consumption per capita per day” multiplied by “regional population values”. Regional rice yields = “country-based production” divided by “harvested area” (multiple harvests are taken into account). Regional rice production = “regional harvested areas” multiplied by “rice yield values”. We compared regional rice consumption and production values according to these methods. Analysis of the data sets generated a map of rice supply and demand. Inter-regional shipping costs were not accounted for. This map can contribute to the understanding of food security issues in rice-producing regions and to estimating potential population values in such regions.     

Characterization of the pattern of the nongenomic signaling pathway through which TCDD-induces early inflammatory responses in U937 human macrophages

2,3,7,8-Tetrachlorodibenzo(p)dioxin (TCDD) has been known to induce inflammatory signaling in a number of cell types and tissues. We found that in U937 macrophages TCDD causes rapid activation of cytosolic phospholipase A2 (cPLA2) within 30 min as judged by the increase in the serine 505 phosphorylated form of cPLA2 protein and the increased cellular release of free arachidonic acid. This initial action of TCDD is accompanied with the up-regulation of an important inflammation marker, COX-2 mRNA expression within 1 h, and by 3 h, several other markers become up-regulated. These effects appear to be dependent on the initial increase in the intracellular concentration of Ca²⁺, and activation of cPLA2 and COX-2. A comparative study among three different human cell lines showed that activation of COX-2 within 1 h of action of TCDD is a common feature exhibited by all cell lines. On the other hand, the U937 macrophage line appears to be unique among them with respect to its ability to activate TNF-α and IL-8 mRNA expressions, and not requiring Src kinase in propagating the initial signaling of cPLA2. Based on the rapidity of activation of cPLA2 and COX-2, which occurs within 1 h of cell exposure to TCDD, when no change in mRNA expression of CYP1A1 has been observed, it is apparent that this unique action of TCDD is carried out through a distinct “nongenomic” pathway which, is clearly discernable from the classical, “genomic” action pathway of the AhR by not requiring the participation of ARNT.     

Micro fabrication on cylinder surface for control of wettability

A micro fabrication is presented to control wettability on cylinder surfaces. A machine tool is developed to form the micro-scale structure on the cylinder in incremental stamping. The stamping tool is manufactured with fabricating the micro-scale structure on the top of the tool in FIB sputtering. The micro incremental stamping is repeated with linear motion of the tool and rotation of the workpiece. The rotation is controlled by the friction drive on the machine table because of the stable stamping with reducing bending of the workpiece. The critical stamping depth, the minimum depth in which the structure is formed, is determined in the forming tests using the structured tool. Then, a stripe type structure is formed to control wettability on the cylinder surface. Anisotropic wettability appears on the structured surface.     

Electrochemical reduction of organohalogen compound by noble metal sintered electrode

1,2,3-Trichlorobenzene (1,2,3-TCB) was used as a model sample of persistent organic pollutants (POPs) which was dechlorinated by a closed electrochemical reduction system under an inert gas atmosphere. The effect of the electrode material was examined in the reaction. Dechlorination yields in different type of cathode electrodes using sintered RuO2 (major)/Pt/PdO, sintered Pt(major)/IrO2/RuO2, sintered RuO2, sintered PdO, sintered Pt, sintered PdO/Pt, sintered Pd/Pt and plain Pd plate were 91%, 81%, 59%, 96%, 53%, 97%, 82% and 70% respectively, at reaction times of 60 or 120 min. The reaction was exothermic after initially starting at room temperature. This electrochemical reduction system was friendly technology for environment using cation exchange membrane, supplying sodium ions from sodium hydroxide solution as anolyte. Trace amounts of dichlorobenzene, as products of stepwise dechlorination, were observed with different pathways, depending on the electrode material. Electrodes with Ru and Pd were selective mainly for meta-position dechlorination, while those with Pt groups selective mainly for ortho-position (o-position) dechlorination. A PdO sintered electrode had an especially high selectivity for meta-position (m-position) dechlorination. The results suggest that dechlorination is an electrocatalytic reduction in this cation supply system.