Professional
Tobacco Smoke, Radon, and Lung Cancer: Who's at Risk?
by: Jill M. Siegfried, PhD, Co-Director, Thoracic Malignancies Program, UPCI and Professor, Department of Pharmacology, University of Pittsburgh
Air Pollution Increases the Risk of Lung Cancer and Chronic Health Problems
| Particulate Matter Health Effects* | Ground-level Ozone Health Effects** |
|---|---|
| Aggravated asthma | Aggravated asthma and possibly new cases of asthma |
| Increased respiratory symptoms | Reduced lung capacity |
| Increased respiratory and cardiovascular hospitalizations | |
| Chronic bronchitis | Increased susceptibility to respiratory illnesses |
* Particulate Matter: invisible solids and liquids that can remain suspended in the air
** Ground-level ozone: O3; major component of smog Table Reference
U.S. Environmental Protection Agency, Office of Air Quality Planning and Standards. 2005. Review of the national ambient air quality standards for particulate matter: Policy assessment of scientific and technical information (OAQPS staff paper). Research Triangle Park, NC: U.S. Environmental Protection Agency. Report no. EPA-452/R-05-005a.
Lung cancer, the number one cause of death from cancer in the United States, is rapidly becoming the number one cause of cancer death in other parts of the world. More than 160,000 people in the United States died from lung cancer in 2005, more deaths than from breast, prostate, and colon cancer combined.
Tobacco Smoke is the No. 1 Cause of Lung Cancer
Smoking is the number one cause of lung cancer. Eighty-five percent of lung cancer occurs in people who have smoked compared with only 15 percent of lung cancer cases that occur in people who have never smoked. Tobacco smoke contains thousands of chemicals, many of which have been proven to be human carcinogens, including benzo(a)pyrene, nitrosamines, benzene, cadmium, nickel, chromium, and formaldehyde. Other toxins such as carbon monoxide, cyanide, and ammonia are involved in producing cellular damage that leads to chronic inflammation in the lungs. Chronic inflammation releases molecules that tell the cells to grow and this process can lead to tumor formation.
Figure 1
Lung Cells → Cancer Causing Chemicals → Cells with Genetic Damage (mutations) → Inflammation → Growth of Defective Cells → Lung Cancer
Some of the cells that are exposed to carcinogens acquire genetic damage that is not repaired. The fact that about 50 percent of new cancer cases are diagnosed in people who have quit smoking, some who have been tobacco-free for more than 20 years, shows that the genetic damage (mutations) caused to the lungs from the carcinogens in tobacco smoke is not easily reversed. When the damaged lung cells respond to the cell growth signals produced by chronic inflammation, there is an increased chance that the damaged dividing cells will form a tumor (Figure 1).
Even nonsmokers who live or work in smoke-filled environments are at an increased risk for lung cancer. In fact, working one eight-hour shift in a smoke-filled bar may be equivalent to actively smoking nearly one pack of cigarettes. You do not have to actively smoke cigarettes to be at increased risk of lung cancer. In fact, environmental tobacco smoke, inhaled by those in proximity to active smokers (passive smoking), is also a confirmed lung carcinogen. It is estimated that 3,400 people die every year from lung cancer caused by passive smoke exposure.1 The U.S. Surgeon General's 2006 Report titled "The Health Consequences of Involuntary Exposure to Tobacco Smoke: A Report of the Surgeon General" recently confirmed that there is no safe level of exposure to environmental tobacco smoke, and that it is especially damaging to the health of children.
Source
1. Siegel, M. Smoking and Restaurants: A Guide for Policy-Makers. Oakland, CA: Alameda County Health Care Services Agency, Tobacco Control Program, et al., 1992.
Radon is the No. 2 Cause of Lung Cancer
While environmental tobacco smoke has received much attention recently, the importance of another key risk factor, exposure to naturally-occurring radon, is largely unappreciated by the general public. Radon gas is actually the second leading cause of lung cancer, after active smoking. Up to 21,000 deaths from lung cancer each year in the United States are attributed to radon gas. Radon can induce lung cancer in those who have never smoked. It can also increase the risk of lung cancer in smokers because radon gas lodges in the lungs and releases radioactive particles. Radon gas enters the environment from the earth's crust, and the extent of exposure depends upon geographical location. Allegheny County falls in the highest category, the "red" zone, for probable radon exposure, with estimates of average indoor exposure that exceed recommended levels. The U.S. Environmental Protection Agency recommends that homes be remediated if radon indoors exceeds 4 picoCuries/liter.
The Need to be Proactive
Residents of Allegheny County can be exposed to both high levels of radon and tobacco smoke. It is important to test your home for radon. For more information, call the Radon Division Hotline of the PA Department of Environmental Protection at (800) 237-2366. To take action in support of a local ordinance (Legislative File Number 2705-06 (version 1)) prohibiting smoking in public places and workplaces, contact your local representative. See [sidebar to "Clearing The Smoke"].
