Advances in animal care technology at the National Center for Toxicological Research.

The research purpose of the NCTR as it relates to animal care emphasizes the improvement of protocols for safety assessments, the study of irreversible lesions, and the use of valid animal models. The development, building, and operation of the "A" Barrier were described. The "A" Barrier is a complex of equipment, instrumentation, and rooms with controlled entry designed to prevent introduction of microoranisms or environmental factors into the SPF animal colonies. Support facilities such as computer controls and pathology were also described. The first experimental compound being tested is 2-acetylaminofluorene (2-AAF) which will be administered to a total of 25,000 mice in some 72 different treatment groups at 7 dose levels. The desired end-product of the center is to produce a series of tests which can be done quickly, efficiently, and economically and allow for a realistic estimate of risk to man of suspected toxic chemicals.