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.
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 method is composed of the main test and the limit test. This Test Guideline is intended for use with the adult rat, rabbit or guinea pig. At least 20 animals (10 female and 10 male) with healthy skin should be used at each dose level (at least three). The highest dose level should result in toxic effects but not produce an incidence of fatalities. The limit test corresponds to one dose level of at least 1000 mg/kg body weight. The method is based on the repeated application of the substance of interest during one limited period (several hours daily during 90 days). The test substance should be applied over not less than 10 per cent of the body surface area. The results of this study include: measurements and daily and detailed observations (ophthalmological examination, haematology, clinical biochemistry and urinalysis), as well as gross necropsy and histopathology. A properly conducted subchronic test should provide a satisfactory estimation of a non effect level.
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.
The revised Test Guideline describes two studies: a traditional LC50 protocol and a Concentration x Time (C x t) protocol. It can be used to estimate a median lethal concentration (LC50), non-lethal threshold concentration (LC01) and slope, and to identify possible sex susceptibility. This Test Guideline enables a test article quantitative risk assessment and classification according to the Globally Harmonized System for the Classification and Labelling of Chemicals. In the traditional LC50 protocol, animals are exposed to one limit concentration or to three concentrations, at least, for a predetermined duration, generally of 4 hours. Usually 10 animals should be used for each concentration. In the C x T protocol, animals are exposed to one limit concentration or a series of concentrations over multiple time durations. Usually 2 animals per C x t interval are used. Animals (the preferred species is the rat) should be observed for at least 14 days. The study includes measurements (including weighing), daily and detailed observations, as well as gross necropsy.
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.
Emerging Field of Synthetic Biology” was held in July 2009 in Washington, DC
under the auspices of the United States National Academies, the Organisation
for Economic Co-operation and Development and the Royal Society.
The OECD Programme for International Student Assessment (PISA) seeks to answer these questions through the most comprehensive and rigorous international assessment of student knowledge and skills. PISA 2012 Assessment and Analytical Framework presents the conceptual framework underlying the fifth cycle of PISA. Similar to the previous cycles, the 2012 assessment covers reading, mathematics and science, with the major focus on mathematical literacy. Two other domains are evaluated: problem solving and financial literacy. Students respond to a background questionnaire and, as an option, to an educational career questionnaire as well as another questionnaire about Information and Communication Technologies (ICTs). Additional supporting information is gathered from the school authorities through the school questionnaire and from the parents through a third optional questionnaire. Sixty-six countries and economies, including all 34 OECD member countries, are taking part in the PISA 2012 assessment.
Data are provided for all OECD member countries (including area totals), and for Brazil, China, India, Indonesia, the Russian Federation and South Africa. For each indicator, there is a two-page spread: a text page includes a short introduction followed by a detailed definition of the indicator, comments on comparability of the data, an assessment of long-term trends related to the indicator and a list of references for further information on the indicator; the second page contains a table and a graph providing, at a glance, the key message conveyed by the data. Each indicator includes "StatLinks" which allow readers to download the corresponding data.
OECD Countries covered include Australia, Austria, Belgium, Canada, Chile,Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Israel, Italy, Japan, Korea, Luxembourg, Mexico, Netherlands, New Zealand, Poland, Portugal, Slovak Republic, Slovenia, Spain, Sweden, Switzerland, Turkey, the United Kingdom, and the United States. Non-OECD countries covered include Brazil, China, India, Indonesia, Russia, and South Africa.
Topics covered include population and migration; production and productivity; household income, wealth and debt; globalisation, trade and foreign direct investment (FDI); prices, interest rates and exchange rates; energy and transportation; labour, employment and unemployment; science and technology including research and development (R&D) and the Information and Communications Technology (ICT) sector; environment including natural resoures, water,and air and climate; education resources and outcomes; government expenditures, debt, revenues, taxes, agricultural support and foreign aid; and health status, risk and resources.
The OECD Factbook is also available as a free app for your mobile device! Visit your app store.
PISA Computer-Based Assessment of Student Skills in Science describes how the 2006 survey was administered, presents 15-year-olds’ achievement scores in science and explains the impact of information communication technologies on both males’ and females’ science skills. While males outperformed females on the computer-based test in all three countries, females in Iceland and males in Denmark performed better than their counterparts on the paper-and-pencil test. The evidence shows that, overall, males are more confident and use computers more frequently. While females tend to use the Internet more for social networking activities, males tend to browse the Internet, play games and download software.
Readers will also learn how students reacted to the electronic questionnaire and how it compared with pencil-and-paper tests. In general, there were no group differences across test methods buts students enjoyed the computer-based test more than the paper-and-pencil test.
This new publication is a product of the OECD-Eurostat Entrepreneurship Indicators Programme, which is a long-term programme of internationally-comparable policy-relevant entrepreneurship statistics. The work involves developing standard definitions and concepts and engaging countries and international Agencies in the collection of data. An international group of statisticians and analysts provides guidance to the Programme that benefits from sponsorship by the Ewing Marion Kauffman Foundation in the United States.
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.