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 albino rabbit is the preferable laboratory animal. The substance to be tested is applied in a single dose to a small area of skin (approximately 6cm2) of an experimental animal; untreated skin areas of the test animal serve as the control. The exposure period is 4 hours. Residual test substance should then be removed. The dose is 0.5ml (liquid) or 0.5g (solid) applied to the test site. The method consists of two tests: the initial test and the confirmatory test (used only if a corrosive effect is not observed in the initial test). All animals should be examined for signs of erythema and oedema during 14 days. The dermal irritation scores should be evaluated in conjunction with the nature and severity of lesions, and their reversibility or lack of reversibility. When responses persist to the end of the 14-day observation period, the test substance should be considered an irritant.
This Test Guideline is intended primarily for use with rats and mice, and for oral administration. Both sexes should be used. Each dose group and concurrent control group should contain at least 50 animals of each sex. At least three dose levels and a concurrent control should be used. Animals are dosed with the test substance daily (oral, dermal or inhalation administration) and the mode of exposure should be adjusted according to the toxicokinetic profile of the test substance. The duration of the study will normally be 24 months for rodents. For specific strains of mice, duration of 18 months may be more appropriate. Termination of the study should be considered when the number of survivors in the lower dose groups or the control group falls below 25 per cent. The results of these studies include: measurements (weighing, food consumption), and, at least, daily and detailed observations, as well as gross necropsy and histopathology.
Balb/c 3T3 cells are maintained in culture for 24 h for formation of monolayers. Two 96-well plates are pre-incubated with eight different concentrations of the test substance for 1 h. Thereafter one of the two plates is exposed to the highest non-cytotoxic irradiation dose whereas the other plate is kept in the dark. Cytotoxicity in this test is expressed as a concentration-dependent reduction of the uptake of the Vital dye Neutral Red (NR) when measured 24 hours after treatment with the test chemical and irradiation. NR penetrates cell membranes by non-diffusion, accumulating in lysosomes. Alterations of the cell surface of the sensitive lysosomal membrane lead to lysosomal fragility and other changes that gradually become irreversible. Such changes result in a decreased uptake and binding of NR. It is thus possible to distinguish between viable, damaged or dead cells. To predict the phototoxic potential, the concentration responses obtained in the presence and in the absence of irradiation are compared, usually at the IC50 level, i.e., the concentration reducing cell viability to 50 % compared to the untreated controls.
Software to be used with TG 425, 432, 455. Click here. Software not part of the Mutual Acceptance of Data.
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 and females of the Parent generation (5-9 weeks old) should be dosed during growth, during their mating, during the resulting pregnancies, and through the weaning of their first generation offspring. The administration of the substance is continued to first generation offspring during their growth into adulthood, mating and production of a second generation (until the weaning). The rat is the preferred species for testing. Each test and control group should contain a sufficient number of animals to yield preferably not less than 20 pregnant females at or near parturition. At least three dose levels and a concurrent control shall be used. It is recommended that the test substance be administered orally (by diet, drinking water or gavage). 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, sperm parameters, oestrus cycle parameters and offspring parameters), clinical daily observations, as well as gross necropsy and histopathology. The findings of this two-generation reproduction toxicity study should be evaluated in terms of the observed effects including necropsy and microscopic findings. A properly conducted reproductive toxicity test should provide a satisfactory estimation of a no-effect level and an understanding of adverse effects on reproduction, parturition, lactation, postnatal development including growth and sexual development.
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.
The test material (150 μL for liquids or solid with 150 μL of deionised water added on the top) is applied for up to 24 hours to the epidermal surfaces of skin discs (three skin discs are used for each test and control substance) in a two-compartment test system in which the skin discs function as the separation between the compartments. The skin discs are taken from humanely killed rats aged 28-30 days. Corrosive materials are identified by their ability to produce a loss of normal stratum corneum integrity and barrier function, which is measured as a reduction in the TER below a threshold level (5kΩ for rat). A dye-binding step incorporated into the test procedure permits to determine if the increase in ionic permeability is due to physical destruction of the stratum corneum.
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 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.
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.
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.