Publications & Documents

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 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.

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 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.

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.  

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 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.