The Division of Translational Toxicology (DTT) performs systematic reviews of literature to assess the potential for adverse effects on human health by agents, substances, mixtures, or exposure scenarios, based on information about human exposure. The findings of these reviews generally focused on either cancer or non-cancer effects and published as monographs. This review on polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs was conducted in support of the congressionally mandated Report on Carcinogens (ORoC). The ORoC lists substances that pose a cancer hazard for people living in the United States, and documents related to the cancer hazard evaluation of substances as potential new listings in the report. Keywords: Systematic review, toxicology, epidemiology, exposure, cancer effects