An in vivo/in vitro Toxicological Screen (Tox Screen) has been developed for screening large numbers of wastes for biological activity. Emphasis is placed on identifying a wide range of potential toxic responses by employing diverse test methods with toxic endpoints in mutagenesis/carcinogenesis, general toxicology, neurotoxicology, reproductive toxicology, teratology, teratology, and immunotoxicology. Oral administration of waste material is given to rats for 10 consecutive days after which the whole animal, body tissues and fluids are evaluated for toxicity. The Tox Screen is being validated to ensure that the protocol will be capable of detecting biological activity and to identify those assays which most readily detect toxicity. The most accurate and sensitive assays would be used as a Prescreen for the entire protocol. Results of the validation study with 4 toxic chemicals are included. Acrylamide produced its greatest effects in the neurotox assays and in mutagenesis.