Chemical dosimetry in somatic cells and its utility to mutagenesis.

In assessing the potential health hazard a given mutagen might present to man, a number of extrapolations must be made from the test systems which are currently available. For the L5178Y mouse lymphoma cell assay system that we use, these extrapolations include: somatic versus germinal cells; single cells versus whole animals; transformed versus "normal" cells; and mouse versus human cells. All of these factors represent potentials for ameliorating or enhancing the mutagenic effects of a given agent, especially by altering the extent of interaction between mutagen and DNA. By quantitating this interaction for the various test systems, the confidence with which mutagenic data can be meaningfully extrapolated to man is greatly improved. Problems of dosage interpretation of mutagenic agents arise as a consequence of innate differences in the many different mutagen assay systems. Dr. Rall has outlined some of these problems earlier (1). It is important for us to realize that the interactions of a chemical agent with DNA in a test tube may not mimic the reaction that occurs in a mammalian cell. While the interaction itself may be interesting and educational, it may or may not relate to the actual mutagenic initiation event in an intact animal. Certain classes of environmental agents are known to interact either physically or chem-