The test material (solid or liquid) is applied uniformly and topically to a three-dimensional human skin model, comprising at least a reconstructed epidermis with a functional stratum corneum. Two tissue replicates are used for each treatment (exposure time), and for controls. Corrosive materials are identified by their ability to produce a decrease in cell viability below defined threshold levels at specified exposure periods. The principle of the human skin model assay is based on the hypothesis that corrosive chemicals are able to penetrate the stratum corneum by diffusion or erosion, and are cytotoxic to the underlying cell layers.
The test material (solid or liquid) is applied uniformly and topically to a three-dimensional human skin model, comprising at least a reconstructed epidermis with a functional stratum corneum. Two tissue replicates are used for each treatment (exposure time), and for controls. Corrosive materials are identified by their ability to produce a decrease in cell viability below defined threshold levels at specified exposure periods. Coloured chemicals can also be tested by used of an HPLC procedure. The principle of the human skin model assay is based on the hypothesis that corrosive chemicals are able to penetrate the stratum corneum by diffusion or erosion, and are cytotoxic to the underlying cell layers.
The Test Guideline focuses on rodents and oral administration. Both sexes should be used. For rodents, at least 20 animals per sex per group should normally be used at each dose level, while for non-rodents a minimum of 4 per sex per group is recommended. At least three dose levels should be used in addition to the concurrent control group. Frequency of exposure normally is daily, but may vary according to the route chosen (oral, dermal or inhalation) and should be adjusted according to the toxicokinetic profile of the test substance. The duration of the exposure period should be 12 months. The study report should include: measurements (weighing) and regular detailed observations (haematological examination, urinalysis, clinical chemistry), as well as necropsy procedures and histopathology.
This Test Guideline recommends rats or mice as the test species. Generally, male animals are exposed to the test substance and mated to untreated virgin females. The most widely used is the single administration of the test substance by oral or by intraperitoneal injection. Normally, three dose levels should be used. The various germ cell stages can be tested separately by the use of sequential mating intervals. The females are sacrificed after an appropriate period of time, and the contents of the uteri are examined to determine the numbers of implants and live and dead embryos. The calculation of the dominant lethal effect is based on comparison of the live implants per female in the treated group to the live implants per female in the control group.
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.
The test method utilizes an artificial membrane designed to respond to corrosive substances in a manner similar to animal skin in situ. The in vitro membrane barrier test method may be used to test solids, liquids (aqueous substances with a pH in the range of 4.5 to 8.5 often do not qualify for testing) and emulsions. The test described in this Test Guideline allows the identification of corrosive chemical substances and mixtures and allows the subcategorisation of corrosive substances as permitted in the GHS. This classification is based on the substance penetration time through the membrane barrier. The test system is composed of two components, a synthetic macromolecular bio-barrier and a Chemical Detection System (which one detect the test substance). An appropriate number of replicates is prepared for each test substance and its corresponding controls. The times of applying the test substance to the membrane barrier are recorded and staggered. The time (in minutes) elapsed between application of the test substance to the membrane barrier and barrier penetration is used to predict the corrosivity of the test substance.
Males should be dosed during growth and for at least one complete spermatogenic cycle; females of the Parent generation should be dosed for at least two complete oestrous cycles. The animals are then mated. The test substance is administered to both sexes during the mating period and thereafter only to females during pregnancy and for the duration of the nursing period. This Test Guideline is intended primarily for use with the rat or mouse. Each test and control group should contain a sufficient number of animals to yield about 20 pregnant females at or near term. Three test groups, at least, should be used. It is recommended that the test substance be administered in the diet or drinking water. A limit test may be performed if no effects would be expected at a dose of 1000 mg/kg bw/d. The results of this study include measurements (weighing, food consumption) and daily and detailed observations, each day preferably at the same time, as well as gross necropsy and histopathology. The findings of a reproduction toxicity study should be evaluated in terms of the observed effects, necropsy and microscopic findings. A properly conducted reproduction test should provide a satisfactory estimation of a no-effect level and an understanding of adverse effects on reproduction, parturition, lactation and postnatal growth.
Skin from human or animal sources can be used. Although viable skin is preferred, non-viable skin can also be used. The skin has been shown to have the capability to metabolise some chemicals during percutaneous absorption. In this case, metabolites of the test chemical may be analysed by appropriate methods. Normally more than one concentration of the test substance is used in typical formulations, spanning the realistic range of potential human exposures. The application should mimic human exposure, normally 1-5 mg/cm2 of skin for a solid and up to 10 μl/cm2 for liquids. The temperature must be constant because it affects the passive diffusion of chemicals. The absorption of a test substance during a given time period (normally 24h) is measured by analysis of the receptor fluid and the distribution of the test substance chemical in the test system and the absorption profile with time should be presented.
This Test Guideline is intended primarily for use with guinea pig, but recently mouse models for assessing sensitisation potential have been developed. For the GPMT at least 10 animals in the treatment group and 5 in the control group are used. For the Buehler test, a minimum of 20 animals is used in the treatment group and at least 10 animals in the control group. The test animals are initially exposed to the test substance. Following a rest period, the induction period (10-14 days), during which an immune response may develop, then the animals are exposed to a challenge dose. The GPMT is made during approximately 23-25 days, the Buehler test, during approximately 30-32 days. The concentration of test substance used for each induction exposure should be well-tolerated systemically and should be the highest to cause mild-to moderate skin irritation, for the challenge exposure the highest nonirritant dose should be used. All skin reactions and any unusual findings should be observed and recorded (other procedures may be carried out to clarify doubtful reactions).
Investment for Development provides a record of the OECD Investment Committee's co-operation programmes with non-member economies and their results. These extensive co-operation activities are organised around three dimensions: global events, regional initiatives and dialogue with individual countries. This report documents how these initiatives help to strengthen implementation capacities and best practices among non-members, drawing on the broad applicability of the principles and expertise the OECD has developed in the area of international investment, including the positive contribution of responsible international business.
Host countries are not alone in advancing this agenda. Home countries have a key role to play too. One example is the role of official development assistance in mobilising private investment. Investment for Development includes a report that identifies policy lessons and the analytical evidence that underpins them.
The report offers a comprehensive overview of the rapidly changing phenomenon of Open Educational Resources and the challenges it poses for higher education. It examines reasons for individuals and institutions to share resources for free, and looks at copyright issues, sustainability and business models as well as policy implications. It will be of particular interest to those involved in e-learning or strategic decision making within higher education, to researchers and to students of new technologies.
This book assembles information on the space economy from a wide range of official and non-official sources. Together these paint a richly detailed picture of the space industry, its downstream services activities, and its wider economic and social impacts. Who are the main space-faring nations? How large are revenues and how much employment is there in the sector? How much R&D goes on, and where? What is the value of spin-offs from space spending? Answers to these and other questions are provided in this second OECD statistical overview of the emerging space economy.
A dynamic link (StatLink) is provided for graphs, which directs the user to a web page where the corresponding data are available in Excel® format.
This report provides an overview of the economic impact of ICT on economic performance, and the ways through which it can be measured. Using available OECD data, the first part of the book examines the available measures of ICT diffusion, the role and impact of ICT investment and the role of ICT-using and ICT-producing sectors in overall economic performance. The second part of the book offers nine studies for OECD countries, based on detailed firm-level data and prepared by researchers and statisticians from a wide range of OECD countries. These studies use a variety of methods and provide detailed insights on the effects of ICT in individual countries.
This report offers policy insights and stimulates new research to complement and further develop the recent OECD Teaching and Learning International Survey (TALIS) and the upcoming PISA 2012 assessment, which will again focus on mathematics. In addition, this report may be of interest to teachers, educators and officials within national and local educational authorities responsible for the professional development of teachers or for programme development, as well as members of school boards and parent advisory bodies.
New material in this edition includes: entry rates in tertiary education by field of study; data on the skills of 15-year-olds in science; an analysis of the socio-economic background of 15-year-olds and the role of their parents; data on the extent to which the socio-economic status of parents affects students' participation in higher education; data on the returns to education; data on the governance of higher education institutions; an analysis of efficiency in the use of resources; data on evaluations and assessments within education systems; and a comparison of the levels of decision-making in education across countries
Excel® spreadsheets used to create the tables and charts in this book are available via the StatLinks printed in this book. The tables and charts, as well as the complete OECD Online Education Database, are freely available via the OECD Education website at www.oecd.org/edu/eag2008.
After a brief introduction to the PISA assessment, the book presents three chapters, including PISA questions for the reading, mathematics and science tests, respectively. Each chapter presents an overview of what exactly the questions assess. The second section of each chapter presents questions which were used in the PISA 2000, 2003 and 2006 surveys, that is, the actual PISA tests for which results were published. The third section presents questions used in trying out the assessment. Although these questions were not used in the PISA 2000, 2003 and 2006 surveys, they are nevertheless illustrative of the kind of question PISA uses. The final section shows all the answers, along with brief comments on each question.