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The aim of the Evaluation-guided Development of New In Vitro Test Batteries (EDIT) multicentre programme is to establish and validate in vitro tests relevant to toxicokinetics and for organ-specific toxicity, to be incorporated into optimal test batteries for the estimation of human acute systemic toxicity. The scientific basis of EDIT is the good prediction of human acute toxicity obtained with three human cell line tests (R2 = 0.77), in the Multicentre Evaluation of In Vitro Cytotoxicity (MEIC) programme. However, the results from the MEIC study indicated that at least two other types of in vitro test ought to be added to the existing test battery to improve the prediction of human acute systemic toxicity — to determine key kinetic events (such as biotransformation and passage through biological barriers), and to predict crucial organ-specific mechanisms not covered by the tests in the MEIC battery. The EDIT programme will be a case-by-case project, but the establishment and validation of new tests will be carried through by a common, step-wise procedure. The Scientific Committee of the EDIT programme defines the need for a specific set of toxicity or toxicokinetic data. Laboratories are then invited to perform the defined tests in order to provide the “missing” data for the EDIT reference chemicals. The results obtained will be evaluated against the MEMO (the MEIC Monograph programme) database, i.e. against human acute systemic lethal and toxicity data. The aim of the round-table discussions at the 19th Scandinavian Society for Cell Toxicology (SSCT) workshop, held in Ringsted, Denmark on 6–9 September 2001, was to identify which tests are the most important for inclusion in the MEIC battery, i.e. which types of tests the EDIT programme should focus on. It was proposed that it is important to include in vitro methods for various kinetic events, such as biotransformation, absorption in the gut, passage across the blood–brain barrier, distribution volumes, protein binding, and renal clearance/accumulation. Models for target organ toxicity were also discussed. Because several of the outlier chemicals (paracetamol, digoxin, malathion, nicotine, paraquat, atropine and potassium cyanide) in the MEIC in vivo–in vitro evaluation have a neurotoxic potential, it was proposed that the development within the EDIT target organ programme should initially be focused on the nervous system.

The ACuteTox project is designed to replace animal testing for acute systemic toxicity, as is widely used today for regulatory purposes, by using in vitro and in silico alternatives. In spite of the fact that earlier studies on acute systemic toxicity demonstrated a good correlation between in vitro basal cytotoxicity data (the 50% inhibitory concentration [IC50]) in human cell lines and rodent LD50 values, and an even better correlation between IC50 values and human lethal blood concentrations, very few non-animal tests have been accepted for general use. Therefore, the aim of the ACuteTox project is to adapt new testing strategies, for example, the implementation of new endpoints and new cell systems for toxicity screening, organ-specific models, metabolism-dependent toxicity, tissue absorption, distribution and excretion, and computer-based prediction models. A new database, AcuBase, containing descriptions and results of in vitro tests of the 97 reference chemicals, as well as the results of animal experimentation, and human acute toxicity data, will be generated within the framework of ACuteTox. Scientists from 13 European countries are working together and making efforts to find the most appropriate testing strategies for the prediction of human acute systemic toxicity, and also to select a robust in vitro test battery for cytotoxicity testing of chemicals.