More people die of lung cancer in the United States than die of colon, prostate, breast, and kidney cancers combined. What surprises many people is that lung cancer is not necessarily caused by smoking. Many at risk groups and nonsmokers are also likely to develop the disease.

Some of the people who are the most at risk are United States veterans who served in the military between the Second World War and the Persian Gulf War. Recent studies indicate that this group has a 25% to 75% greater probability of developing lung cancer than people who didn't serve in the military during that time frame.

There's a very simple reason why this is true. Many of the people who risked their lives while serving in the U.S. military were exposed to Agent Orange, asbestos, DU (depleted uranium), as well as other radioactive materials during their tenure in the military.

The groups of veterans who are at the most risk are all of those who served during the Vietnam era as well as those who were in the Navy during the Second World War.

Asbestos was used extensively throughout naval ships during the 1940s. It was present in sleeping quarters, mess halls, boiler rooms, engine rooms - just about everywhere aboard the ships.

Anyone who was on one of the ships was constantly inhaling asbestos fibers. And, when they went home, they carried the fibers on their clothes. Subsequently their families were exposed to asbestos secondhand.

Asbestos-related lung cancer, or mesothelioma, has a very long latency period. Since the mid 1980s a significant number of Navy veterans have died from these diseases. Some World War II veterans are only now developing these illnesses.

However, because the Veterans Administration doesn't recognize these diseases as being service-connected it is difficult for the vets to realize any Veterans Affairs benefits.

Close to 2.6 million Americans served in Viet Nam. Most of them were exposed to Agent Orange.

Between 1965 and 1971, during the Viet Nam War, more than 100 million pounds of Agent Orange was used. It was used to destroy plant life and clear the brush in order to remove the Viet Cong cover. The herbicide has since proven to cause serious medical ailments, including lung cancer, in Viet Nam era vets.

Much like asbestos related diseases, there seems to be a latency period before the adverse effects caused by Agent Orange develop. So, many of these veterans are just starting to develop symptoms.

Unlike WW II veterans, though, lung cancer in Vietnam era vets is considered to be a service related disease. Hence the Veterans Administration will provide disability compensation to anyone who is diagnosed with lung cancer that was caused by Agent Orange.

Gulf War veterans are now becoming concerned with the dangerous after effects of being exposed to depleted uranium while they were overseas. The residue from DU munitions floats through the air and ultimately infiltrates such water sources as lakes, oceans, and rivers.

US military personnel were also exposed to DU when they came into contact with bunkers and vehicles that were hit by these munitions.

DU has been linked to causing lung cancer, as well as kidney and bone ailments. Although tumors can form in 2 to 5 years, they are often not diagnosed until several years after the fact.