Carbazole (CAR), a heterocyclic aromatic compound containing a dibenzopyrrole system, is produced during coal gasification and in cigarette smoke. Coal tar produced at high temperature contains an average of 1.5% carbazole. Several thousand tons of carbazole are produced each year from coal tar and crude oil. It is used widely in synthesis of dyes, pharmaceuticals, and plastics and is a suspected carcinogen. This pathway was proposed based on the identification of metabolites and the comparison with other aromatic compound degradative pathways such as biphenyl and naphthalene ([http://www.ncbi.nlm.nih.gov/pubmed/9244273|Sato et al., 1997]).