COMMENTARY Harmonisation of the micronucleus assay in human buccal cells—a Human Micronucleus (HUMN) project (www.humn.org) initiative commencing in 2007

The buccal cell micronucleus (MN) assay, first proposed by Stich et al. (1,2), is useful as a biomarker of genetic damage caused by life-style habits (e.g. consumption of tobacco products and alcohol, micronutrient deficiency), exposures to environmental pollutants (e.g. pesticides, arsenic, formalde-hyde), medical procedures (e.g. radio- and/or chemotherapy), as well as, inherited genetic defects in DNA repair (1–18). The non-invasive nature of this technique makes it an attractive candidate for the bio-monitoring of human popula-tions or individuals. However, the increased use of the MN assay in buccal cells, has led to a wide diversity in techniques, timing for cell collection relative to exposure period, cell and nuclear staining procedures, numbers and types of cells analysed, and scoring criteria for micronuclei (MNi) and other nuclear anomalies (e.g. karyorrhexis, condensed chro