Genotoxicity: damage to DNA and its consequences.

A genotoxin is a chemical or agent that can cause DNA or chromosomal damage. Such damage in a germ cell has the potential to cause a heritable altered trait (germline mutation). DNA damage in a somatic cell may result in a somatic mutation, which may lead to malignant transformation (cancer). Many in vitro and in vivo tests for genotoxicity have been developed that, with a range of endpoints, detect DNA damage or its biological consequences in prokaryotic (e.g. bacterial) or eukaryotic (e.g. mammalian, avian or yeast) cells. These assays are used to evaluate the safety of environmental chemicals and consumer products and to explore the mechanism of action of known or suspected carcinogens. Many chemical carcinogens/mutagens undergo metabolic activation to reactive species that bind covalently to DNA, and the DNA adducts thus formed can be detected in cells and in human tissues by a variety of sensitive techniques. The detection and characterisation of DNA adducts in human tissues provides clues to the aetiology of human cancer. Characterisation of gene mutations in human tumours, in common with the known mutagenic profiles of genotoxins in experimental systems, may provide further insight into the role of environmental mutagens in human cancer.