Cigarette Smoke. Smoking causes 87% of lung cancer deaths, and accounts for 30% of all cancer-related deaths. Cigarettes, nicotine, or both may contribute to lung cancer in one or more of the following ways:
- The smoke is the most dangerous component of the cigarette. Chemicals formed during smoking trigger genetic mutations that lead to cancer. When people inhale cigarette smoke, they bring into their lungs tar that includes over 4,000 chemicals, some of which are carcinogenic (cancer-causing). Other inhaled chemicals in cigarette smoke that may increase the risk for cancer include cyanide, benzene, formaldehyde, methanol (wood alcohol), acetylene (the fuel used in torches), and ammonia. Smoke also contains nitrogen oxide and carbon monoxide, both harmful gases.
- Nicotine is responsible for the addicting properties of tobacco. It is not clear if nicotine itself plays a role in the growth of cancer cells. In any case, nicotine replacement products are much, much safer than tobacco.
Radon. Radon is a gas produced naturally by the breakdown of uranium. It is often present in the soil and in water and can seep into any dwelling. Radon is the second leading cause of lung cancer.
Other Contributors. Toxic particles leading to precancerous changes in the lung are also found in marijuana. Multiple studies report an association between abnormal lung changes and marijuana smoking.
There is considerable debate over the lung cancer risk posed by depleted uranium used in military weapons (such as in the Gulf and Balkan conflicts).
Review Date: 07/01/2010
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.