ABSTRACT
A critical component in assessing the effect of low-level exposure to toxicants is the repair of a genome that may be damaged by the agent. Because the adverse effect of many low-level toxicants is below practical observable thresholds, models are necessary to extrapolate the observable effects to realistic levels. One of the most important factors in the protection of genomic integrity is Deoxyribonucleic Acid (DNA) repair. This chapter focuses on excision repair, which directly reverses the effects of a toxicant binding to the DNA. Just as DNA repair modulates the response of a genome to an insult, DNA repair is itself modulated by a number of environmental factors. Among the important modulators of DNA repair are age, nutrition, and toxicants themselves. The best characterized system used to understand the effects of toxicants in modulating DNA repair is the adaptive response, seen in E. coli and mammalian cells.
