In vivo sister-chromatid exchange: a sensitive measure of DNA damage.

A variety of chemical agents and X-irradiation were examined for their abilities to induce sister-chromatid exchanges (SCE) in vivo. In addition to demonstrating that several known mutagens and carcinogens are capable of inducing SCE in vivo, our studies indicate that the suspected carcinogen, tris-bromophosphate, can significantly elevate SCE levels. Comparison of the effects of these agents on SCE levels, chromosomal-aberration frequencies and cell-replication kinetics reveals that no consistent relationship exists between SCE levels and other indicators of cellular DNA damage. It is proposed that analysis of SCE induction in vivo may provide a useful technique for the screening of mutagenic and carcinogenic compounds.