“…One set of a few methods, such as a twocompartment system with an interposed monolayer of cells to mimic chemical transport as well as tests for binding to cells or proteins, plus physicochemical data (see Turner et al, 1987) might predict the distribution of varied blood concentrations of a chemical in man as different concentrations in the extracellular water of various compartments of the body (brain, kidney tubuli, biliary canaliculi, thyroid follicles, gastric mucosal linings, etc.). Further, this modeling is thought to be accomplished in three steps: 1) The testing of the chemical for its toxicity in several relevant in vitro systems, such as cell lines, human hepatocytes, heart-, kidney-, and nerve cells, in vitro systems representing vitally important human neurotransmission systems, and so forth.…”