A micronucleus assay was developed using HSC-3TO, a human continuous lymphoblastoid cell line (LCL) and cytochalasin B (Cyt-B) to block cytokinesis. Mitomycin C (MMC), a chemotherapeutic agent and an inducer of micronuclei in various human cell types, was used as a positive control. MMC induced micronuclei in HSC-3TO at levels over six times that of control cells when cells were treated with the D₅₀ dose (i.e., the dose of MMC which was toxic to 50% of treated cells). It was found that harvest time was a very important variable and that a harvest time of 108 hours was optimal. 2-Nitrofluoranthene (2-NFA), a nitrated polycyclic aromatic hydrocarbon, the most abundant nitroarene found in the particulate organic matter fraction of ambient air and a potent direct-acting mutagen in the Ames Salmonella assay, was tested using the established CBMN assay protocol. Doses (20, 200 and 2000 ng/mL 2-NFA) were chosen based on the estimated yearly total body exposure and did not produce elevated levels of micronuclei at a dose of 100 times the estimated yearly total body exposure. / Thesis / Master of Science (MS)