Comet-assay parameters as rapid biomarkers of exposure to dietary/environmental compounds -- an in vitro feasibility study on spermatozoa and lymphocytes.

Twelve chemical compounds have been selected for the European NewGeneris study on the basis of their potential to damage DNA, in order to establish adequate and reliable biomarkers of exposure. These genotoxic chemicals include heterocyclic amines, organochlorines, polycyclic aromatic hydrocarbons, mycotoxins, lipid peroxidation products and alcohol. Damage in somatic cells such as lymphocytes could give rise to cancer, while damage in germ cells could not only give rise to cancer but also to heritable defects. The alkaline Comet assay, with and without metabolic activation, as well as the neutral Comet assay were used to assess DNA integrity in spermatozoa and lymphocytes after in vitro treatment with low, middle and high doses of each chemical. DNA-reactive aldehydes generated by lipid peroxidation, food mutagens such as heterocyclic amines, nitrosamine and benzo[a]pyrene produced the highest amounts of DNA damage, even without metabolic activation. Damage seen with the neutral Comet assay - detecting primarily double-strand breaks - was lower than with the alkaline assay. In general, there was increased damage in the spermatozoa by comparison with the lymphocytes, with altered slopes in the dose-response curves. The Comet assay with sperm was generally very sensitive in assessing genotoxic damage, with the Comet parameters being good biomarkers of induced DNA damage. Establishing reliable biomarkers of exposure for the evaluation of dietary/environmental carcinogens is of utmost importance to protect our health and the health of our offspring.