text: These include genotoxicity testing, human biomonitoring and molecular epidemiology, ecogenotoxicology, as well as fundamental research in DNA damage and repair.  For example, Swain and Rao, using the comet assay reported marked increases in several types of DNA damages in rat brain neurons and astrocytes during aging, including single-strand breaks, double-strand breaks and modified bases (8-OHdG and uracil).