The DNA that makes up the human genome is under constant attack from reactive chemicals that are generated inside the body, or absorbed as pollutants via the air we breathe, water we drink or the food we eat. If not neutralized, these genotoxic agents both damage and mutate the DNA, causing cancer and possibly other diseases. A key task in biochemical toxicology, therefore, is to assess the reactivity and genotoxic potential of these chemicals, such that appropriate precautions may be taken. Bringing the power of biochemical analysis to toxicology, this modern reference explains genotoxicity at the molecular level, showing the links between a DNA lesion and the resulting cellular or organismic response. It is clearly divided into two main sections, with Part 1 focusing on selected examples of important DNA lesions and their biological impact, while the second part covers current advances in assessing and predicting the genotoxic effects of chemicals, taking into account the biological responses mediated by the DNA repair, replication and transcription machineries. The result is a ready reference for biochemists, toxicologists, molecular biologists, geneticists, and cell biologists seeking a better understanding of the impact of chemicals on human health.