Chemical carcinogenesis is the onset of cancer due to the exposure to the toxins released into the environment. This is a very important phenomenon as most of the human cancer deaths are caused due to the exposure to various chemicals and environmental toxins. Carcinogens do not cause cancer all the time. Carcinogens posses different risk levels of causing cancer. The risk level might be low, causing benign cancer and some may have prolonged effect due to high exposure levels. The risk level depends on the type of carcinogen, duration of exposure, the intensity of exposure and the genetic makeup of the individual. Chemical carcinogens pose a great threat to each and every biological organism that exists on the earth. They affect all kind of ecosystems, like land, air and marine.