Biomarkers in the molecular epidemiology of benzene-exposed workers.

Biomarkers can be classified into three categories: biomarkers of exposure, susceptibility, and early effect. Along with colleagues from the National Cancer Institute, the Chinese Academy of Preventive Medicine in Beijing, the Shanghai Anti-Epidemic Center, the University of North Carolina, and other institutions in the United States, we have applied various biomarker methods to samples obtained from workers exposed to high levels of benzene. The goal of these studies is to develop and validate (1) biomarkers of exposure to benzene, such as albumin or hemoglobin adducts; (2) molecular markers of susceptibility to benzene, such as inherited polymorphisms in enzymes involved in the metabolism of benzene; and (3) biomarkers of the early effects of benzene, including hematotoxicity (complete blood cell counts), gene mutations (glycophorin A), and chromosome aberrations detected by fluorescence in situ hybridization (FISH), G-banding, and the micronucleus assay. An introduction to these studies has been presented previously (Rothman et al., 1996a, 1996b; Smith & Rothman, 1998; Smith & Zhang, 1998), and only those findings pertaining to biomarkers of exposure and early effects are discussed here.