Approximately 63,000 chemicals are found in our foods, drugs, consumer products and environment. There is proof that human exposure to some of these chemicals can have carcinogenic, teratogenic and mutagenic effects. Several standard short-term tests are routinely employed to test for the occurrence of these mutagenic conditions. They include chromosomal breakage and rearrangement (clastogenicity) assays, gene mutation assays, and cell death assays (reduction in mitotic index or cell colonies). Chromosomal aberrations are a common cell response to mutagenic exposure. Recently the micronucleus test has gained popularity as a more rapid, less expensive method with which to detect this type of damage. Mutagenic exposure in dividing cells may cause chromosome damage producing acentric chromatid or chromosome fragments. Treatment of these cells with a known mutagenic and clastogenic compound, with the addition of a cytokinetic block, will determine if this cell line can be used for the detection and determination of micronuclei.