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Earth's orbits are polluted by more than 100 million debris objects that pose a collision threat to satellites and other spacecraft. The risk of perturbing highly valuable space-based services critical to life on Earth, such as weather monitoring and disaster management, is making debris mitigation an urgent policy challenge. This book provides the latest findings from the OECD project on the economics of space sustainability, which aims to improve decision makers’ understanding of the societal value of space infrastructure and costs of space debris. It provides comprehensive evidence on the growth of space debris, presents methods to evaluate and quantify the value of the satellites at risk and discusses ways to ensure a more sustainable use of the orbital environment. It notably includes case studies from Italy, Japan and Korea on the socio-economic value of different types of space infrastructure and discusses the feasibility and optimal design of fiscal measures and voluntary environmental rating schemes to change operator behaviour. This work is informed by contributions from researchers worldwide involved in the OECD project.

This Test Guideline describes an in vitro procedure the identification on its own of chemicals (substances and mixtures) not requiring classification (No Cat), requiring classification for eye irritation (Cat 2) and requiring classification for serious eye damage (Cat 1) according to the UN GHS ocular hazard categories. It makes use of reconstructed human cornea-like epithelium (RhCE) which closely mimics the histological, morphological, biochemical and physiological properties of the human corneal epithelium. The test evaluates the ability of a test chemical to induce cytotoxicity in a RhCE tissue construct, as measured by the MTT assay. RhCE tissue viability following exposure to a test chemical is measured by enzymatic conversion of the vital dye MTT by the viable cells of the tissue into a blue MTT formazan salt that is quantitatively measured after extraction from tissues. Cytotoxicity is measured at different time points of exposure; this is one of the methodological differences with the original TG 492.

This Performance-Based Test Guideline (PBTG) describes in vitro assays, which provide the methodology for human recombinant in vitro assays to detect substances with estrogen receptor binding affinity (hrER binding assays). It comprises two mechanistically and functionally similar test methods for the identification of estrogen receptor (i.e. ERα) binders and should facilitate the development of new similar or modified test methods. The two reference test methods that provide the basis for this PBTG are: the Freyberger-Wilson (FW) In Vitro Estrogen Receptor (ER) Binding Assay Using a Full Length Human Recombinant ERα, and the Chemical Evaluation and Research Institute (CERI) In Vitro Estrogen Receptor Binding Assay Using a Human Recombinant Ligand Binding Domain Protein. This assay measures the ability of a radiolabeled ligand ([3H]17β-estradiol) to bind with the ER in the presence of increasing concentrations of a test chemical (i.e. competitor).  Test chemicals that possess a high affinity for the ER compete with the radiolabeled ligand at a lower concentration as compared with those chemicals with lower affinity for the receptor. This assay consists of two major components: a saturation binding experiment to characterise receptor-ligand interaction parameters and document ER specificity, followed by a competitive binding experiment that characterises the competition between a test chemical and a radiolabeled ligand for binding to the ER. These test methods are being proposed for screening and prioritisation purposes, but also provide mechanistic information that can be used in a weight of evidence approach.

This method provides information on health hazard likely to arise from short-term exposure to a test article (gas, vapour or aerosol/particulate test article) by inhalation.

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 Hyalella azteca Bioconcentration Test (HYBIT) provides a non-vertebrate test for bioconcentration in aquatic environments. The test consists of two phases: the exposure (uptake) and post-exposure (depuration) phases. During the uptake phase, a group of H. azteca is exposed to the test chemical at one or more chosen concentrations. They are then transferred to a medium free of the test chemical for the depuration phase. The concentration of the test chemical in the analysed H. azteca is followed through both phases of the test. Parameters which characterise the bioaccumulation potential include the uptake rate constant (k1), the depuration rate constant (k2), the steady-state bioconcentration factor (BCFSS) and the kinetic bioconcentration factor (BCFK).

This Test Guideline describes an in vitro procedure allowing the identification of chemicals (substances and mixtures) not requiring classification and labelling for eye irritation or serious eye damage in accordance with UN GHS. It makes use of reconstructed human cornea-like epithelium (RhCE) which closely mimics the histological, morphological, biochemical and physiological properties of the human corneal epithelium. The test evaluates the ability of a test chemical to induce cytotoxicity in a RhCE tissue construct, as measured by the MTT assay. Coloured chemicals can also be tested by used of an HPLC procedure. RhCE tissue viability following exposure to a test chemical is measured by enzymatic conversion of the vital dye MTT by the viable cells of the tissue into a blue MTT formazan salt that is quantitatively measured after extraction from tissues. The viability of the RhCE tissue is determined in comparison to tissues treated with the negative control substance (% viability), and is then used to predict the eye hazard potential of the test chemical. Chemicals not requiring classification and labelling according to UN GHS are identified as those that do not decrease tissue viability below a defined threshold (i.e., tissue viability > 60%, for UN GHS No Category).

The present Key Event based Test Guideline (TG) addresses the human health hazard endpoint skin sensitisation, following exposure to a test chemical. Skin sensitisation refers to an allergic response following skin contact with the tested chemical, as defined by the United Nations Globally Harmonized System of Classification and Labelling of Chemicals (UN GHS). This TG is proposed to address the activation of dendritic cells, which is one Key Event on the Adverse Outcome Pathway (AOP) for Skin Sensitisation. It provides four in vitro test methods addressing the same Key Event on the AOP: (i) the human cell Line Activation Test or h-CLAT method, (ii) the U937 Cell Line Activation Test or U-SENS, (iii) the Interleukin-8 Reporter Gene Assay or IL-8 Luc assay and (iv) the Genomic Allergen Rapid Detection for assessment of skin sensitisers (GARD™skin). All of them are used for supporting the discrimination between skin sensitisers and non-sensitisers in accordance with the UN GHS. The test methods described in this TG either quantify the change in the expression of cell surface marker(s) CD54 and CD86, the cytokine IL-8, or a series of genes (genomic biomarker signature) that are associated with the process of activation of monocytes and DC following exposure to sensitisers.

The present Key Event based Test Guideline addresses the human health hazard endpoint skin sensitisation, following exposure to a test chemical. Skin sensitisation refers to an allergic response following skin contact with a tested chemical, as defined by the United Nations Globally Harmonized System of Classification and Labelling of Chemicals (UN GHS). This Test Guideline is proposed to address a Key Event leading to skin sensitisation, namely keratinocyte activation. This Key Event on the Adverse Outcome Pathway (AOP) leading to skin sensitisation takes place in the keratinocytes and includes inflammatory responses as well as gene expression associated with specific cell signalling pathways such as the antioxidant/electrophile response element (ARE)-dependent pathways. This Test Guideline provides three in vitro test methods addressing the same Key Event on the AOP for skin sensitisation: (i) the ARE-Nrf2 luciferase KeratinoSens™ test method, (ii) the ARE-Nrf2 luciferase LuSens test method and (iii) the Epidermal Sensitisation Assay – EpiSensA. The KeratinoSens and the Lusens are in vitro ARE-Nrf2 luciferase-based test methods and the EpiSensA is based on gene expression quantification using Reverse Transcription- quantitative PCR in reconstructed human epidermis models. The proposed test methods are used for supporting the discrimination between skin sensitisers and non-sensitisers in accordance with the UN GHS. Performance standards have been developed to enable the validation of similar test methods.

This Test Guideline (TG) describes a short-term juvenile hormone (JH) activity screening assay using Daphnia magna to detect the potential of chemicals with JH activity. The JHASA was designed as a screen assay which evaluates male offspring production in the parthenogenetic daphnid.

This Test Guideline proposes defined approaches (DA) combining data generated in vitro methods, with information sources such as physicochemical properties. The prediction from a DA may be used alone to determine eye hazard potential according to the hazard classes of the UN GHS (Categories 1, 2, or not classified). A DA consists of a fixed data interpretation procedure (DIP) (i.e. a mathematical model, a rule-based approach) applied to data (e.g in silico predictions, in chemico, in vitro data) generated with a defined set of information sources to derive a prediction without the need for expert judgment. The DAs use method combinations intended to overcome some of the limitations of the individual, stand-alone methods in order to provide increased confidence in the overall obtained result.

The in vitro macromolecular test method is a biochemical in vitro test method that can be used to identify chemicals (substances and mixtures) that have the potential to induce serious eye damage as well as chemicals not requiring classification for eye irritation or serious eye damage. The in vitro macromolecular test method contains a macromolecular reagent composed of a mixture of proteins, glycoproteins, carbohydrates, lipids and low molecular weight components, that when rehydrated forms a complex macromolecular matrix which mimics the highly ordered structure of the transparent cornea. Corneal opacity is described as the most important driver for classification of eye hazard. Test chemicals producing protein denaturation, unfolding and changes in conformation will lead to the disruption and disaggregation of the highly organised macromolecular reagent matrix, and produce turbidity of the macromolecular reagent. Such phenomena is quantified, by measuring the changes in light scattering (at a wavelength of 405 nm using a spectrometer), which is compared to the standard curve established in parallel by measuring the increase in OD produced by a set of calibration substances.

The present Key Event based Test Guideline addresses the human health hazard endpoint skin sensitisation, following exposure to a test chemical. Skin sensitisation refers to an allergic response following skin contact with the tested chemical, as defined by the United Nations Globally Harmonized System of Classification and Labelling of Chemicals (UN GHS). This Test Guideline is proposed to address the Molecular Initiating Event leading to skin sensitisation, namely protein reactivity, by quantifying the reactivity of test chemicals towards model synthetic peptides or amino acid derivatives containing either lysine or cysteine. This Test Guideline provides three in chemico test methods addressing the same Key Event on the Adverse Outcome Pathway for Skin Sensitisation: (i) the Direct Peptide Reactivity Assay – DPRA, (ii) the Amino Acid Derivative Reactivity Assay – ADRA and (iii) the kinetic Direct Peptide Reactivity Assay – kDPRA. The DPRA and ADRA are used for supporting the discrimination between skin sensitisers and non-sensitisers in accordance with the UN GHS. In contrast, the kDPRA allows discrimination of UN GHS subcategory 1A skin sensitisers from those not categorised as subcategory 1A, i.e. subcategory 1B or no category but does not allow to distinguish sensitisers from non-sensitisers.

This Test Guideline describes a Rapid Estrogen ACTivity In Vivo (REACTIV) Assay in an aquatic assay that utilises transgenic Oryzias latipes (Japanese medaka) eleutheroembryos at day post hatch zero, in a multi-well plate format to identify chemicals active on the estrogen axis. The REACTIV assay was designed as a screening assay to provide a medium throughput and short-term assay to measure the response of eleutheroembryos to chemicals potentially active on the estrogen axis.

Over 100 million workers in Southeast Asia have jobs that are directly or closely linked to the environment, making them vulnerable to climate change impacts. These same workers likely earn at least 20% lower than the national average and are largely in informal employment. The region’s necessary transition towards greener growth could affect them in several ways: some sectors will create jobs and others will lose jobs or disappear altogether. Understanding the effects of both climate change and green growth policies on jobs and people is thus essential for making the transition in Southeast Asia an inclusive one. The study explores these issues, with emphasis on the potential effects on labour of an energy transition in Indonesia, and of a transition in the region’s agricultural sector, illustrated by a simulated conversion from conventional to organic rice farming.

The re-opening of Samoa’s borders in late-2022 kickstarted the country’s recovery from the COVID-19 pandemic. This offers an opportunity to rebuild sustainably its tourism, maritime transport, and fisheries sectors. Samoa’s ocean resources can also augment its resilience to future shocks such as climate change. Through an analysis of Samoa’s economic trends and environmental pressures, institutional set-up and policy tools, as well as financing landscape, this report identifies opportunities and challenges for Samoa’s ocean economy to drive sustainable and resilient development. The Samoa Ocean Strategy offers a blueprint for such a pursuit, but there remain gaps and impediments. To address them, the report provides several cross-cutting and sector-specific policy recommendations to accelerate Samoa’s transition to a sustainable ocean economy.

The Climate Action Monitor is a key publication of the International Programme for Action on Climate (IPAC). It provides a synthesis of climate action and progress towards net-zero targets for 51 OECD and OECD partner countries. This year's edition presents a summary of information on greenhouse gas emissions, an assessment of climate-related hazards and recent trends in climate action. Directed towards policymakers and practitioners, the findings suggest that without increased ambition and a significant expansion in national climate action, countries will not be able to meet the net-zero challenge.

This Test Guideline describes the Medaka Extended One Generation Test (MEOGRT), which exposes fish over multiple generations to give data relevant to ecological hazard and risk assessment of chemicals, including suspected endocrine disrupting chemicals (EDCs).  Exposure in the MEOGRT starts with spawning fish (P or F0 generation) and continues until hatching (until two weeks post fertilization, wpf) in the second (F2) generation. This Test Guideline measures several biological endpoints.  Primary emphasis is given to potential adverse effects on population relevant parameters including survival, gross development, growth and reproduction (fecundity).  Secondarily, in order to provide mechanistic information and provide linkage between results from other kinds of field and laboratory studies, where there is a posteriori evidence for a chemical having potential endocrine disrupter activity (e.g. androgenic or oestrogenic activity in other tests and assays) then other useful information is obtained by measuring vitellogenin (vtg) mRNA (or vitellogenin protein, VTG), phenotypic secondary sex characteristics (SSC) as related to genetic sex, and evaluating histopathology.