Chapter 12 . Biomarkers of Air Pollution: Dna and Protein Adducts

Biomarkers were introduced in the epidemiology of chronic disease under the assumption that they could enhance research on the health effects of air pollution, and other exposures, by improving exposure assessment, increasing the understanding of mechanisms (e.g. by measuring intermediate biomarkers), and enabling the investigation of individual susceptibility. Biomarkers used in the epidemiology of cancer are usually divided into three categories: markers of internal dose, markers of early response, and markers of susceptibility. In fact, each category includes subcategories. For example, protein adducts and DNA adducts are both markers of internal dose, but their biological significance differs. While protein adducts are not repaired (i.e. they reflect external exposure more faithfully), DNA adducts are influenced by an individual’s repair capacity. If DNA adducts are not eliminated by the DNA repair machinery, they induce a mutation. Also, markers of early response are a heterogeneous category that encompasses DNA mutations and gross chromosomal damage. The main advantage of early response markers is that they are more frequent than the disease and can be recognized sooner, thus allowing researchers to identify earlier effects of potentially carcinogenic exposures. Finally, markers of susceptibility include several subcategories; in particular, a type of genetic susceptibility related to the metabolism of carcinogenic substances, and another type related to DNA repair. Biomarkers of exposure, such as DNA adducts, are described here, while markers of early damage are considered in a separate chapter.