Cancer, which is an uncontrolled growth of cells that has deleterious effects on organs and other body tissues, can be linked to exposure to certain chemicals in the environment. Cancer cells become deleterious when they multiply to the point where they invade neighboring tissue and eventually spread to other body systems. Often times, the cell’s out-of-control growth is initiated by repeated exposure to a toxic chemical, also called a carcinogen. Chemicals and cancer incidence go hand in hand. The majority of research on the etiology of cancer focuses on specific environmental causation, like chemical exposure in the workplace or exposure as result of lifestyle choice, for example.
The link between chemicals and cancer begins when a chemical carcinogen initiates a change within deoxy-ribonucleic acid (DNA), a process called initiation. Under normal circumstances, the body’s defense system can identify and repair the damaged portions of the DNA, but if the cell begins to reproduce while, the damage is still present within the genetic code, and an abnormal cell with cancerous potential is the result. A single, or a few, instances of the initiation process is usually not enough to cause cancer to develop; other factors, usually termed “promoters," are often seen, which seem to be present when uncontrollable growth takes place. These promoters include factors like exposure to the initial chemical in high amounts over a long period of time, nutritional deficiency, or a genetic predisposition towards cancer. The link between chemicals and cancer is not fully understood, but most researchers agree that one of these promoters is usually present when cancer develops.
The research into chemicals and cancer has been conducted for decades; perhaps the most well-known study of industrial and tobacco smoke as a potential carcinogen began in the United States in the 1930’s. Over the decades, dozens of cancer-causing chemicals, like benzopyrene and formaldehyde, have been found in industrial and cigarette smoke. Another example of a common chemical that is of concern is polyvinyl chloride, produced when PVC pipe is manufactured. Its presence in many applications used by the population makes it one of many chemicals that scientists continue to research in order to understand their specific carcinogenic mechanisms. Research of chemicals and cancer extends to using certain chemicals to treat cancer when it arises, which is called chemotherapy.
Cause-and-effect relationships between chemicals and cancer can be seen with benzene and leukemia, asbestos and lung cancer, and vinyl chloride and liver cancer. The risk of cancer becomes significantly higher when carcinogenic chemicals are encountered together. An example of this concept can be seen in factory workers who are exposed to toxic workplace smoke on an everyday basis; workers who smoke in addition to this exposure have a 50% higher chance of developing lung cancer.