Smokeless is not harmless.
That's the latest news on tobacco use, according to a new study published in the international journal Tobacco Control.
American Cancer Society epidemiologists Jane Henley and colleagues followed a group of 116,395 men who switched from cigarettes to smokeless tobacco and compared them with 111,952 men who quit using tobacco entirely between 1982 and 2002.
Compared with the total quitters, there was an 8 percent increase in death from any cause in the "switcher" group.
Worse, there was a 46 percent increase in lung cancer, a 13 percent increase in heart disease, and a 24 percent increase in stroke in the group that switched to smokeless tobacco.
Smokeless tobacco, also known as spit tobacco, comes in several varieties, mainly chewing tobacco and snuff.
While the use of smokeless tobacco had been declining in the United States during the late 1990s, it increased from 9.8 million users to 10.4 million users between 2004 and 2005, according to the federal Substance Abuse and Mental Health Agency. The increase was greatest among adults 26 years and older -- about 6 percent in that group.
Why might this be happening? One likely explanation is that adult smokers have switched from cigarettes to smokeless tobacco as a means to quit smoking.
Previous studies had suggested that smokeless tobacco increased heart disease death rates among users, but there was some remaining uncertainty about this relationship.
According to the authors, this new study strongly confirmed this association. Henley and her coworkers said, "Spit tobacco contains numerous chemicals, such as nicotine, sodium and licorice that are known to affect cardiovascular function adversely."
Thus, it is no surprise that heart disease would increase among switchers compared when compared with total quitters.
Nicotine, for example, increases heart rate, blood pressure and cholesterol. The typical smokeless tobacco user receives 10 times more nicotine with each use than does a cigarette smoker.
Previous research also confirmed that smokeless tobacco use was associated with cancer, especially cancers of the mouth and pancreas. Spit tobacco contains a 100-fold greater amount of the cancer-causing agents, nitrosamines, than the Food and Drug Administration allows in food products.
One of these nitrosamines, abbreviated as NNK, causes lung cancer in laboratory animals regardless of whether it is inhaled, taken by mouth or injected.
Henley's new research is particularly timely, because a number of leading tobacco experts actually recommend that smokers quit smoking by switching to smokeless tobacco.
As recently as December 2006, Dr. Brad Rodu, professor of medicine and director of tobacco harm reduction research at the University of Louisville, wrote in the Harm Reduction Journal that a "substantial body of research, much of it produced over the past decade, establishes the scientific and medical foundation for tobacco harm reduction using smokeless tobacco products [as a means to quit smoking]."
Two factors significantly fueled this push for using smokeless tobacco to quit smoking. The first was a report in 2001 by the Institute of Medicine called "Clearing the Smoke: Assessing the Science Base for Tobacco Harm Reduction."