ABSTRACT
It is important to appreciate that promoting agents may give the appearance of complete carcinogens by promoting cells initiated by ambient environmental agents. This chapter reviews some environmental inhaled carcinogens, and presents salient generalizations of chemical carcinogenesis because an understanding of this is essential for a preventive approach. Carcinogenesis requires a long time for its full expression, and its biology is extremely complex. It is recognized that chemical carcinogenesis is a multistage process, consisting of at least two steps: initiation and promotion. For lung cancer, the main causative agent is known, namely inhaled tobacco smoke, but other carcinogenic substances are also being identified both in the ambient environment and the workplace. In several subsequent case-control studies, the association between kerosene fuel use and lung cancer was found to be weak and not significant, with no clearly defined dose-response relationship.
