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  • 25-June-2024

    English

    Test No. 493: Performance-Based Test Guideline for Human Recombinant Estrogen Receptor (hrER) In Vitro Assays to Detect Chemicals with ER Binding Affinity

    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.
  • 25-June-2024

    English

    Test No. 442D: In Vitro Skin Sensitisation - Assays addressing the Adverse Outcome Pathway Key Event on Keratinocyte activation

    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.
  • 25-June-2024

    English

    Test No. 442B: Skin Sensitization - Local Lymph Node Assay: BrdU-ELISA or –FCM

    The Local Lymph Node Assay: BrdU-ELISA (LLNA:BrdU-ELISA) is a non-radioactive modification to the LLNA method for identifying potential skin sensitizing test substances and measuring the proliferation of lymphocytes they induce in the auricular lymph nodes. The method described in mouse  is based on the use of measuring 5-bromo-2-deoxyuridine (BrdU) content, an analogue of thymidine, as an indicator of this proliferation. A minimum of four animals is used per dose group, with a minimum of three concentrations of the test substance, plus a concurrent negative control group and a positive control group. The experimental schedule is during 6 days. Thereafter, the animals are killed and a single cell suspension of lymph node cells (LNC) is prepared. The procedure for preparing the LNC is crucial, in particular for the small lymph nodes in NC animals. Then the BrdU content in DNA of lymphocytes is measured by ELISA using a commercial kit of by Flow Cytometry (FCM). This study includes: measurements (weighing, BrdU) and clinical daily observations. The results are expressed as the Stimulation Index (SI) obtained by calculation from the mean BrdU labelling index. The SI should be ≥1.6 for the ELISA method or ≥2.7 for the FCM method for identifying the test material as a potential skin sensitizer.  
  • 26-February-2024

    English

    Best Available Techniques (BAT) to Prevent and Control Industrial Pollution

    On 8 November 2023, the OECD organised a webinar to explore the current understanding of the Best Available Techniques (BAT) approaches and their future. It addressed key challenges, opportunities for the identification of promising emerging techniques for effective pollution prevention and reduction and the importance of cross-collaboration between regulatory authorities, industries, research institutes and technology providers.

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  • 31-January-2024

    English

    Chemical Safety and Biosafety Progress Report

    The Chemical Safety and Biosafety Progress Report is released every eight months. Its purpose is to provide an update on the projects, events and activities. Information on new publications as well as dates and venues of upcoming events and meetings are given.

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  • 18-July-2023

    English

    Good Laboratory Practice (GLP)

    The OECD Principles of Good Laboratory Practice (GLP) ensure the generation of high quality and reliable test data related to the safety of industrial chemical substances and preparations. The principles have been created in the context of harmonising testing procedures for the Mutual Acceptance of Data (MAD).

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  • 4-July-2023

    English

    Test No. 487: In Vitro Mammalian Cell Micronucleus Test

    The in vitro micronucleus test is a genotoxicity test for the detection of micronuclei in the cytoplasm of interphase cells. Micronuclei may originate from acentric chromosome fragments (i.e. lacking a centromere), or whole chromosomes that are unable to migrate to the poles during the anaphase stage of cell division. The assay detects the activity of clastogenic and aneugenic test substances in cells that have undergone cell division during or after exposure to the test substance. This Test Guideline allows the use of protocols with and without the actin polymerisation inhibitor cytochalasin B. Cytochalasin B allows for the identification and selective analysis of micronucleus frequency in cells that have completed one mitosis, because such cells are binucleate. This Test Guideline also allows the use of protocols without cytokinesis block provided there is evidence that the cell population analysed has undergone mitosis.   
  • 4-July-2023

    English

    Test No. 405: Acute Eye Irritation/Corrosion

    This method provides information on health hazard likely to arise from exposure to test substance (liquids, solids and aerosols) by application on the eye. This Test Guideline is intended preferably for use with albino rabbit. The test substance is applied in a single dose in the conjunctival sac of one eye of each animal. The other eye, which remains untreated, serves as a control. The initial test uses an animal; the dose level depends on the test substance nature. A confirmatory test should be made if a corrosive effect is not observed in the initial test, the irritant or negative response should be confirmed using up to two additional animals. It is recommended that it be conducted in a sequential manner in one animal at a time, rather than exposing the two additional animals simultaneously. The duration of the observation period should be sufficient to evaluate fully the magnitude and reversibility of the effects observed. The eyes should be examined at 1, 24, 48, and 72 hours after test substance application. The ocular irritation scores should be evaluated in conjunction with the nature and severity of lesions, and their reversibility or lack of reversibility. Use of topical anesthetics and systemic analgesics to avoid or minimize pain and distress in ocular safety testing procedures is described.
  • 4-July-2023

    English

    Test No. 460: Fluorescein Leakage Test Method for Identifying Ocular Corrosives and Severe Irritants

    This Test Guideline describes an in vitro assay that may be used for identifying water soluble ocular corrosives and severe irritants as defined by the UN Globally Harmonized System of Classification and Labelling, Category 1. The assay is performed in a well where a confluent monolayer of Madin-Darby Canine Kidney (MDCK) is used as a separation between two chambers. It uses a fluorescein dye as marqueur. The test substance has the potential to impair the junctions of the MDCK cells and thus to increase the monolayer¡¯s permeability. Consequently the fluorescein passes through the monolayer and the fluorescein leakage (FL) increases. The FL is calculated as a percentage of leakage relative to both a blank control and a maximum leakage control. The concentration of test substance that causes 20% FL (FL20, in mg/mL) is calculated and used in the prediction model for identification of ocular corrosive and severe irritants. The cut-off value of FL20 to identify water soluble chemicals as ocular corrosives/severe irritants is ¡Ü 100mg/mL. The FL test method should be part of a tiered testing strategy.
  • 4-July-2023

    English

    Test No. 458: Stably Transfected Human Androgen Receptor Transcriptional Activation Assay for Detection of Androgenic Agonist and Antagonist Activity of Chemicals

    This Test Guideline describes in vitro assays, which use Androgen Receptor TransActivation (ARTA) to detect Androgen Receptor Agonists and Antagonists. The ARTA assay methods are mechanistically and functionally similar test methods that provide information on the transcription and translation of a reporter gene following the binding of a chemical to the androgen receptor and subsequent transactivation. The cell lines used in these assays express AR and have been stably transfected with an AR-responsive luciferase reporter gene, and are used to identify chemicals that activate (i.e. act as agonist) or inhibit (i.e. act as antagonists) AR-dependent transcription. Some chemicals may, in a cell type-dependent manner, display both agonist and antagonist activity and are known as selective AR modulators. The AR is activated following ligand binding, after which the receptor-ligand complex binds to specific DNA responsive elements and transactivates the receptor gene, resulting in an increase cellular expression of the luciferase enzyme. The enzyme then transforms the substrate to a bioluminescent product that can be quantitatively measured with a luminometer. This Test Guideline includes ARTA assays using the AR-EcoScreenTM cell line, the AR-CALUX® cell line, and 22Rv1/MMTV_GR-KO cell line.
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