Carcinogen (definition of)
A carcinogen is any substance that can trigger the development of cancer. Carcinogens include fossil fuels, industrial chemicals, tobacco and its byproducts, substances such as asbestos, nuclear radiation, and more. For example, studies have confirmed that exposure to asbestos is the leading risk factor associated with mesothelioma (like peritoneal mesothelioma and pericardial mesothelioma).
Carcinogens cause uncontrolled cellular growth anywhere in the body. Through mechanisms that medical science does not yet fully understand, groups of cells undergo mutation at the molecular level, and start dividing indefinitely. Eventually, these cells form a mass, which is known as a malignant neoplasm or tumor. These abnormal cells are actually parasites that compete with normal cells of the body for energy and nutrition.
Although these molecular changes are still somewhat of a mystery, researchers have discovered connections to genetic damage and chronic inflammation. Carcinogens interact with healthy cells on the level of molecular DNA and trigger these mutations that result in cells that are virtually immortal - until they kill their host body.