In the previous parts of this research, we studied the historical, sociological, and public policy impact of the former manufactured gas plant site at Gowanus. Gowanus Canal is heavily contaminated with coal tar and was found to be a concern of public health risk from chemical exposure to naphthalene, benzene, toluene, ethylbenzene, and xylene pollutants on former Manufactured Gas Plant (MGP) sites when developed. We studied all these chemicals and their risks to the public around the site. We concluded that Naphthalene is a toxic chemical and has carcinogenic properties. In the present study, with an emphasis on the Chemistry and the metabolic processes, we found that the chemical is not directly harmful. It is the various metabolites which in vivo lead to toxicity. All the chemicals found under the former MGP site we studied are aromatic compounds. Our primary focus for this research is the chemistry and the metabolic processes of Naphthalene. This research may lead to a better understanding of the toxicity of aromatic compounds.