Gamma aminobutyric acid radioreceptor‐assay a possible biomarker for human exposure to certain agrochemicals

Abstract

Cyclodiene insecticides, hexachlorocyclohexanes, pyrethroids, bicyclophosphates, the bicycloorthocarboxylate insecticides and some of their metabolites and environmental degradation products are central nervous system toxicants with high specific binding affinity to the chloride channel of the γ‐ aminobutyric acid (GABA)_A receptor‐ionophore sites. [³⁵S] tertiary‐butylbicyclophosphorothionate (TBPS) with specific activity higher than 60 Ci/mmole has a high binding affinity to the same sites and is now commercially available and can be used to label the GABA_A receptor for the development of a radioreceptor assay technique. The GABA receptor was prepared by ultra centnfugation and dialysis of brain homogenates of either cow, goat, rat or catfish. The receptor was then labeled with [³⁵S] TBPS and the assay was conducted by measuring the displacement of radioactivity following incubation with samples containing the analytes. A radioreceptor assay protocol was developed to measure the amount of the α‐endosulfan in blood samples. The assay was extremely sensitive, and can detect 0.2 nM of endosulfan at a level equivalent to 0.08 ppb or 8x10^‐11 gm of endosulfan in each ml of the blood samples.     

Improving situational awareness through the design of offshore installations

Maintaining the situational awareness of control room operators on offshore installations contributes to the timely diagnosis of conditions and making appropriate decisions. This is particularly important when dealing with events and incidents. Recent initiatives aimed at reducing operators’ exposure to the hazards of working on offshore installations may have a negative impact upon situational awareness within the control room environment.This paper discusses mitigation of the negative impact through the design and operation of the installation and control system; either by improving the general level of situational awareness or by specifically targeting the areas affected by these initiatives.     

Estimation of terrestrial chemical spill risk factors using a modified Delphi approach

The large number of chemical spills each year in the United States presents a potentially significant risk to human health and the environment. In an effort to manage this risk, the authors are developing a screening tool to assess the immediate threat to human and environmental receptors from land-based chemical spills. As part of this development effort, a modified Delphi survey was employed to determine the most important factors governing this risk and the relative importance of these factors. Results of the survey indicate that accounting for the attributes of the spilled chemical as well as the characteristics of the surrounding environment is imperative in making informed decisions regarding spill planning and mitigation. Survey results further indicate the greatest concern during spill events to be the risk to human health, which must be considered directly as well as factored into decisions concerning the protection of environmental receptors.     

PM10中重金属的健康风险评估及修正方法比较

通过对华南某电子垃圾拆解区PM₁₀中重金属含量特征分析,计算该地区的人群暴露量,评估人群健康风险,并引入靶器官毒性剂量法（TTD）和证据权重法（WOE）对常规评估方法的非致癌健康风险进行修正,比较探讨3种方法对非致癌健康风险评估结果的影响.结果表明：研究区域夏,冬季节的非致癌和致癌健康风险均为：儿童>成年女性>成年男性,重金属Ni对人群可能存在致癌风险（ILCR在10^-6~10^-4之间）.其中,Cr,Pb,Cd和As 4种重金属（类金属）对成年男性的非致癌健康风险值为3.05×10^-2,经TTD法和WOE法修正后为5.41×10^-2和5.4×10^-1,表明当综合考虑重金属作用的靶器官及重金属间的相互作用时,PM₁₀中重金属的非致癌健康风险值高于常规方法.     

Local recycling of plant nutrients from small-scale wastewater systems to farmland—A Swedish scenario study

Reducing the negative impact from on-site systems and promoting recycling are important tasks for municipal authorities, especially as regards phosphorus. The objective of this scenario study was to compare energy turnover in a life cycle perspective, recycling potential and expected reduction of nitrogen and phosphorus emissions for three upgraded small-scale wastewater systems based on local recycling of plant nutrients. The systems studied were urine separation, blackwater separation and chemical precipitation in the septic tank. The urine was sanitised through storage, the blackwater through liquid composting and the precipitated sludge through chemical treatment with urea before reuse in agriculture. The system boundaries included the operational phase as well as investment in capital goods required for upgrading the existing on-site systems.The urine separation system used least energy. The potential recycling and reduction of phosphorus was lower than for the other two systems, while that of nitrogen was higher than for the chemical precipitation system but lower than for the blackwater separation system. The blackwater separation system reduced both nitrogen and phosphorus to a high extent and also enabled a large proportion of both nitrogen and phosphorus to be recycled to arable land. However, a major drawback with this system was its significantly higher use of electricity, related to the aeration and stirring required when sanitising the blackwater by liquid composting. When urea treatment replaced liquid composting, the use of electricity decreased substantially in the blackwater separation system. The chemical precipitation system was efficient in reducing and recycling phosphorus, while inefficient for nitrogen. The use of fossil fuels was significantly higher than for the other two systems, primarily due to the production of the precipitation chemical.     

人为失误与应激

探讨了人机系统中人为失误与不同应激的相关性.按照模糊集理论,根据成员功能结构,提出了定义正常应激范围的方法以及过高过低应激导致的事故等不良后果.     

Causes and consequences of salt-marsh erosion in an Atlantic estuary in SW Spain

This study reports on the quantification of horizontal erosion by undermining of slopes in the atlantic mesotidal salt marshes of Odiel, SW Spain, and analyses its causes and consequences. Horizontal erosion has produced considerable losses of salt marsh area, including zones of mature salt marsh. Human pressure, such as from water-borne traffic or the exploitation of the slopes for the capture of bait, increases the natural erosion processes. The role of vegetation in protecting the slopes against erosion is studied. Channel banks covered with plants, many of which belong to species with long-living, above-ground creeping stems, were less eroded than those without vegetation cover. The enormous volume of sediments moved (ca. 7000m³ in one year) could contribute to the silting-up of the navigable channels of the estuary, so that continual dredging is necessary to allow access to shipping. These sediments are highly contaminated, and dredging exposes them more directly to the trophic network of the estuary. There is a considerable loss of natural resources. Finally, the integrated management of this coastal ecosystem is discussed.     

Mineral content of drinking water in lowland papua

This study presents concentration of nine minerals (Na, K, Mg, Ca, Cl, Mn, Zn, Cd, Pb) in 31 drinking water samples collected in the Papua New Guinea lowland, where coastal villagers draw water from artificial wells blended with sea water, riverside villagers utilize brackish river water, and inland villagers fetch creek or swamp water whose chemical composition is close to rain water. During the dry season, the coastal well water contains 500 mgL⁻¹ of sodium and 50–90 μgL⁻¹ of lead. The inland creek or swamp water contains very small amount of minerals; on the average, for instance, 0.64 mgL⁻¹ of magnesium, 0.84 mgL⁻¹ of calcium, and 4.78 mgL⁻¹ of water hardness (as CaCO₃). From some epidemiological evidence in industrialized countries, these mineral concentrations are judged to be indicative of high risk of cardiovascular disorders.     

人为失误原因分析与控制对策研究

研究了人为失误对系统安全的影响，分析了人为失误产生的原因及其影响因素，并就煤矿安全管理中人为失误的控制提出了针对性措施     

Congener-distribution patterns and risk assessment of polychlorinated biphenyls,dibenzo-p-dioxins and dibenzofurans in Korean human milk

Polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and biphenyls (PCBs) were analyzed by high-resolution gas chromatography/high-resolution mass spectrometry in human milk samples from an urban and an industrial area in Korea. All PCB congeners were analyzed to characterize the congener distribution as well as to evaluate the toxic equivalent quotient (TEQ) values and the total concentration. In homologue distributions of PCBs, two distinct patterns were found. The mean concentrations of PCDD/Fs and PCBs were 15.13 and 5.64 TEQ pg/g fat (based on WHO TEF, 1997), respectively. The contamination in Korean human milk is comparable to that found in other countries. From these results a daily intake of 60 TEQ pg/kg/day for an infant was estimated. The assumptions were that the infant breast feeds for 1 year, has an average body weight of 10 kg during this period, and ingests 800 g/day of human milk containing a mean concentration of 20.84 TEQ (PCDD/Fs) pg/g fat (based on primipara mothers).