Micronucleus assay

The cytokinesis-block micronucleus (CBMN) assay was carried out according to the method of Fenech and Morley[21] After various treatments, lymphocyte cultures were incubated at 37°C and 44 h from the culture initiation, cytochalasin B (5 μg/ml) was added to arrest cytokinesis. The cultures were harvested at 72 h after initiation and cells were collected by centrifugation. These lymphocytes were subjected to a mild hypotonic (0.56% potassium chloride) treatment for 2 min, centrifuged and fixed in Carnoy's fixative (3:1 methanol, acetic acid).