Browse by: "T"
Index
Title Index
Year Index
This Test Guideline describes methods to determine the boiling point of test substances. The boiling point of a liquid is defined as the temperature (in K) at which the vapour pressure equals the standard atmospheric pressure 101.325 kPa.
The influence of impurities on the boiling point depends greatly upon the nature of the impurity. The methods described in this Test Guideline can be applied to liquid and low-melting substances, provided that they do not undergo chemical change below the boiling point. The methods are: the ebulliometer, the dynamic method, the distillation method, the method according to Siwoloboff, the photocell detection, the differential thermal analysis, the differential scanning calorimetry. The photocell detection and thermal analysis permit the determination of boiling as well as melting temperatures. The dynamic method has the advantage that it can also be applied to the determination of the vapour pressure.In recent years, the challenges of environmental protection, railway privatisation, the impact of logistical requirements, and falling prices, among other things, have revolutionised freight transport markets. The forces of change have spurred new patterns of market organisation which may undergo even more radical upheavals if transport prices come to reflect the sector's true economic and social costs. Round Table 99 undertook a thorough analysis of the potential impact of such trends on the structure and operation of the freight transport sector, and of their effects on government policies.
Controlling public spending is a priority for OECD countries. Salary policy in the public sector is therefore of particular concern. This new annual report analyses recent trends in public sector pay in OECD countries. It examines the links between public expenditure and public sector compensation costs, and presents recent developments in pay determination systems in the public sector. It provides information on the level and the components of individual remuneration for a typical employee in ten selected occupations, and identifies various mechanisms implemented in countries to make individual pay more flexible. Every year, a chapter focusing on a specific experience in the public sector pay area will be added. This report should be of particular interest to public officials responsible for defining, implementing and monitoring pay policy in the public sector and to experts in pay determination systems, employment systems and industrial relations in the public and private sectors.
To mark its hundredth Round Table on transport economics, the ECMT decided to publish a special issue. Fifty European experts were asked to submit papers examining not only the major issues addressed by transport economics in the past, but also those that are likely to emerge in the future. What are the main difficulties facing transport economics? What have been the main advances and how can they help us to solve problems? What remains to be done? The same fifty experts were then invited to take part in an open debate on the issues which they had raised in their papers, ranging from methodological tools to strategies for European transport policies and from the situation of countries in transition to the environment, intermodal transport, new technologies, infrastructure and many other topics. These papers are presented in this volume which also includes a full summary of the discussions at the Round Table.
The test substance is administered in graduated doses to several groups of males and females. Males should be dosed for a minimum of four weeks; females should be dosed throughout the study (approximately 54 days). Normally, matings “one male to one female” should be used in this study.
This Test Guideline is designed for use with the rat. It is recommended that the test substance be administered orally by gavage. This should be done in a single dose daily to the animals using a stomach tube or a suitable intubation cannula. Each group should be started with at least 10 animals of each sex. Generally, at least three test groups and a control group should be used. Dose levels should be selected taking into account any existing toxicity and (toxico-) kinetic data available. The limit test corresponds to one dose level of at least 1000 mg/kg body weight. The results of this study include measurements (weighing, food/water consumption) and daily detailed observations (including sensory reactivity to stimuli), preferably each day at the same time, as well as gross necropsy and histopathology. The findings of this toxicity study should be evaluated in terms of the observed effects, necropsy and microscopic findings. The evaluation will include the relationship between the dose of the test substance and the presence or absence of observations. Because of the short period of treatment of the male, the histopathology of the testis and epididymus must be considered along with the fertility data, when assessing male reproduction effects.
This publication comprises the twenty introductory reports written by specialists for the Symposium and a full summary of discussions of the Thirteenth International Symposium on theory and practice in transport economics held in Luxembourg, 9-11 May 1995. The conference focused on new problems and solutions in transport.
This Test Guideline describes a procedure for characterising the bioconcentration potential of substances in fish, under flow-through conditions (but semi-static regimes are permissible).
The test consists of two phases: the exposure (uptake) and post-exposure (depuration) phases. During the uptake phase (28 days normally and 60 days maximum), separate groups of four fishes of one species are exposed to at least two concentrations of the test substance. They are then transferred to a medium free of the test substance for the depuration phase. A depuration phase is always necessary unless uptake of the substance during the uptake phase has been insignificant. In addition to the two test concentrations, a control group of fish is held without the test substance. The concentration of the test substance in/on the fish is followed through both phases of the test. During the test, dissolved oxygen, TOC, pH, total hardness and salinity, and temperature should be measured in vessels. The lipid content should be determined on the same biological material as is used to determine the concentration of the test substance, when feasible. Where possible the bioconcentration factor at apparent steady-state (BCF), expressed as a function of the total wet weight of the fish, and the kinetic bioconcentration factor (BCFK) are calculated. The bioconcentration should be expressed in relation to lipid content in addition to whole body weight.
This Test guideline describes the Gel Permeation Chromatography (GPC). This method permits to determine the molecular weight distribution and the average molecular weights (Mn, Mw). GPC is a special type of liquid chromatography in which the sample is separated according to the hydrodynamic volumes of the individual constituents. Low molecular weight is arbitrarily defined as a molecular weight below 1000 dalton.
According to their size, the eluted molecules can or not penetrate in the porous material (typically an organic gel) of which the columns are filled. Thus, the smallest molecules are retained whereas largest elute more quickly. At exit of column, detectors (generally by differential refractometry) provide the refractive index or UV-absorption and yield a simple distribution curve. However, to attribute actual molecular weight values to the curve, it is necessary to calibrate the column by passing down polymers of known molecular weight and, ideally, of broadly similar structure, e.g. various polystyrene standards. For each sample analyzed, two independent experiments must be undertaken.This Test guideline describes the Gel Permeation Chromatography (GPC). This method permits to determine the molecular weight distribution and the average molecular weights (Mn, Mw). GPC is a special type of liquid chromatography in which the sample is separated according to the hydrodynamic volumes of the individual constituents.
According to their size, the eluted molecules can or not penetrate in the porous material (typically an organic gel) of which the columns are filled. Thus, the smallest molecules are retained whereas largest elute more quickly. At exit of column, detectors (generally by differential refractometry) provide the refractive index or UV-absorption and yield a simple distribution curve. However, to attribute actual molecular weight values to the curve, it is necessary to calibrate the column by passing down polymers of known molecular weight and, ideally, of broadly similar structure, e.g. various polystyrene standards. For each sample analyzed, two independent experiments must be undertaken. They have to be analysed individually. Mn, Mw, Mw/Mn must be provided for every measurement.Recent years have witnessed growing concern over the controversial issue of trade and labour standards. In a context of intensified international competition, alleged cases of child labour exploitation or of denial of rights to freedom of association and collective bargaining in some developing countries have been perceived by some in developed countries not only as a violation of human rights but also as unfair trade practices. On the other hand, developing countries generally respond that these concerns are unfounded and reflect disguised protectionist preoccupations. What are the relevant core labour standards in this discussion? Do countries with low levels of core labour standards gain an unfair trade advantage over countries with high standards? What are the advantages and disadvantages of possible mechanisms to promote core labour standards? This study provides the first comprehensive analysis of these questions and reviews evidence for a large number of countries throughout the world.
The separation of infrastructure management from operations is central to efforts under way to reform European railways. But why does Europe favour such separation? What are the expected consequences? What does it mean in practice? What are the advantages and disadvantages? What risks are involved and what are the necessary safeguards? What conclusions do countries already practising separation draw from their experience?
Round Table 103 provided an opportunity for experts from all ECMT Member countries and the United States and Japan to get together to discuss experiences of separation to date or plans for it in the future. This publication provides readers with a comprehensive overview of a subject of major importance for the restructuring of European railways.
This annual publication describes the recent trends in international migration, the magnitude of flows, the different channels for immigration and the nationality of the immigrants concerned. It shows that the criteria for admission to host countries is becoming more selective and more oriented to labour market needs. The report also examines recent policy developments for the control of flows and the integration of immigrants. Special attention is given to the links between migration, free trade and regional economic integration.
Detailed country notes present the main migration characteristics of twenty-six OECD countries and Bulgaria, Romania, and the Slovak Republic. The latter country is included for the first time in the notes. Finally, immigration and social transfers is the topic of a special chapter focusing on analytical issues and results obtained in several OECD countries.
A statistical annex provides tables on foreign and immigrant populations, foreign workers, migration flows and naturalisations.
The purpose of the in vitro chromosome aberration test is to identify agents that cause structural chromosome aberrations in cultured mammalian somatic cells. Structural aberrations may be of two types: chromosome or chromatid.
The in vitro chromosome aberration test may employ cultures of established cell lines, cell strains or primary cell cultures. Cell cultures are exposed to the test substance (liquid or solid) both with and without metabolic activation during about 1.5 normal cell cycle lengths. At least three analysable concentrations of the test substance should be used. At each concentration duplicate cultures should normally be used. At predetermined intervals after exposure of cell cultures to the test substance, the cells are treated with a metaphase-arresting substance, harvested, stained. Metaphase cells are analysed microscopically for the presence of chromosome aberrations.
This test measures chromosome events in spermatogonial germ cells and is, therefore, expected to be predictive of induction of inheritable mutations in germ cells.
Male Chinese hamsters and mice are commonly used. Animals are exposed to the test substance (liquid or solid) by an appropriate route of exposure, usually by gavage or by intraperitoneal injection. Then, they are sacrificed at appropriate times after treatment. Each treated and control group must include at least five analysable males. Test substances are preferably administered once or twice but they may also be administered as a split dose to facilitate administering a large volume of material. Prior to sacrifice, animals are treated with a metaphase-arresting agent. Chromosome preparations are then made from germ cells and stained, and metaphase cells are analyzed for chromosome aberrations. A limit test may be performed if no effects would be expected at a dose of 2000 mg/kg bw/d. Positive results from the in vivo spermatogonial chromosome aberration test indicate that a substance induces chromosome aberrations in the germ cells of the species tested.
The mammalian in vivo micronucleus test is used for the detection of damage induced by the test substance to the chromosomes or the mitotic apparatus of erythroblasts, by analysis of erythrocytes as sampled in bone marrow and/or peripheral blood cells of animals, usually rodents (mice or rats).
The purpose of the micronucleus test is to identify substances (liquid or solid) that cause cytogenetic damage which results in the formation of micronuclei containing lagging chromosome fragments or whole chromosomes. An increase in the frequency of micronucleated polychromatic erythrocytes in treated animals is an indication of induced chromosome damage. Animals are exposed to the test substance by an appropriate route (usually by gavage using a stomach tube or a suitable intubation cannula, or by intraperitoneal injection). Bone marrow and/or blood cells are collected, prepared and stained. Preparations are analyzed for the presence of micronuclei. Each treated and control group must include at least 5 analysable animals per sex. Administration of the treatments consists of a single dose of test substance or two daily doses (or more). The limit dose is 2000 mg/kg/body weight/day for treatment up to 14 days, and 1000 mg/kg/body weight/day for treatment longer than 14 days.
The in vitro mammalian cell gene mutation test can be used to detect gene mutations induced by chemical substances. In the cell lines the most commonly-used genetic endpoints measure mutation at thymidine kinase (TK) and hypoxanthine-guanine phosphoribosyl transferase (HPRT), and a transgene of xanthineguanine phosphoribosyl transferase (XPRT). The TK, HPRT and XPRT mutation tests detect different spectra of genetic events.
Cells in suspension or monolayer culture are exposed to, at least four analysable concentrations of the test substance, both with and without metabolic activation, for a suitable period of time. They are subcultured to determine cytotoxicity and to allow phenotypic expression prior to mutant selection. It is recommended to utilise at least 106cells. Cytotoxicity is usually determined by measuring the relative cloning efficiency (survival) or relative total growth of the cultures after the treatment period. The treated cultures are maintained in growth medium for a sufficient period of time, characteristic of each selected locus and cell type, to allow near-optimal phenotypic expression of induced mutations. Mutant frequency is determined by seeding known numbers of cells in medium containing the selective agent to detect mutant cells, and in medium without selective agent to determine the cloning efficiency (viability). After a suitable incubation time, colonies are counted.
The mammalian in vivo chromosome aberration test is used for the detection of structural chromosome aberrations induced by test compounds in bone marrow cells of animals, usually rodents (rats, mice and Chinese hamsters). Structural chromosome aberrations may be of two types: chromosome or chromatid.
Animals are exposed to the test substance (liquid or solid) by an appropriate route of exposure (usually by gavage using a stomach tube or a suitable intubation cannula, or by intraperitoneal injection) and are sacrificed at appropriate times after treatment. Prior to sacrifice, animals are treated with a metaphase-arresting agent. Chromosome preparations are then made from the bone marrow cells and stained, and metaphase cells are analysed for chromosome aberrations. Each treated and control group must include at least 5 analysable animals per sex. The limit dose is 2000 mg/kg/body weight/day for treatment up to 14 days, and 1000 mg/kg/body weight/day for treatment longer than 14 days.
This Test Guideline has been designed to obtain the information necessary to confirm or to further characterise the potential neurotoxicity of chemicals in adult animals.
This Test Guideline is designed for use with the rat. It specifically addresses the daily oral administration, by gavage, (in the diet, in drinking water or by capsules) of the test substance. When the study is conducted as a separate study, at least 20 animals (10 females and 10 males) should be used in each dose. At least three dose groups and a control group should generally be used. Dose levels should be selected by taking into account any previously observed toxicity and kinetic data available for the test compound or related materials. The dosing regimen may be 28 days, subchronic (90 days) or chronic (1 year or longer). The procedures set out in this Test Guideline may also be used for an acute neurotoxicity study. The limit test corresponds to one dose level of at least 1000 mg/kg body weight. The results of this study include measurements (weighing, food /water consumption), functional tests, and, at least, daily detailed observations (Ophthalmology, haematology, clinical biochemistry and histopathology). At least five males and five females, selected from test group, should be perfused in situ and used for detailed neurohistopathology at the end of the study. The findings of the study should be evaluated in terms of the incidence, severity and correlation of neurobehavioural and neuropathological effects (neurochemical or electrophysiological effects as well if supplementary examinations are included) and any other adverse effects observed.