PAPER: cigarette smoke causes genetic damage within minutes of inhalation..

January 18, 2011 - In research described as "a stark warning" to those tempted to start smoking, scientists are reporting that cigarette smoke begins to cause genetic damage within minutes after being inhaled.

In the study, Stephen Hecht, a professor at the University of Minnesota, and a team of scientists studied the harmful substances in tobacco smoke called "polycyclic aromatic hydrocarbons" or PAHs -- one of the culprits that causes lung cancer. Until now, scientists had not detailed the specific way in which the PAHs in cigarette smoke cause DNA damage in humans.

PAPER: Immediate Consequences of Cigarette Smoking: Rapid Formation of Polycyclic Aromatic Hydrocarbon Diol Epoxides, Yan Zhong, Steven G. Carmella, Pramod Upadhyaya, J. Bradley Hochalter, Diane Rauch, Andrew Oliver, Joni Jensen, Dorothy Hatsukami, Jing Wang, Cheryl Zimmerman, and Stephen S. Hecht (hecht002@umn.edu), Chem. Res. Toxicol., Article ASAP Publication Date (Web): December 27, 2010, ABSTRACT..

To study the damage that smoke creates, Hecht's team added a labeled PAH -- phenanthrene -- to cigarettes and tracked it in 12 volunteers who smoked them. They found that phenanthrene quickly forms a toxic substance in the blood known to trash DNA, causing mutations that can cause cancer.

Within 30 minutes after they smoked the cigarettes, the smokers developed maximum levels of the toxic substance. Researchers said the effect is so fast that it's equivalent to injecting the substance directly into the bloodstream.

"This study is unique," wrote Hecht, an internationally recognized expert on cancer-causing substances found in cigarette smoke and smokeless tobacco. "It is the first to investigate human metabolism of a PAH specifically delivered by inhalation in cigarette smoke, without interference by other sources of exposure such as air pollution or the diet. The results reported here should serve as a stark warning to those who are considering starting to smoke cigarettes."

Hecht and his colleagues point out in the report that lung cancer claims a global toll of 3,000 lives each day, largely as a result of cigarette smoking. Smoking also is linked to at least 18 other types of cancer.

The study appeared in Chemical Research in Toxicology, one of 38 peer-reviewed scientific journals published by the American Chemical Society.

This study also comes shortly after the Surgeon General's latest report on smoking, which also noted the damage that cigarette smoke does to the body's DNA. December 9, 2010 - U.S. Surgeon General's Report: How Tobacco Smoke Causes Disease..)

The scientists said the study's primary drawback was that they used phenanthrene in the study's cigarettes as a substitute for a carcinogenic PAH. "You couldn't give known carcinogens to smokers" because it's unethical, Hecht said. But he added, "Phe (phenanthrene) is about as close as we could get to a carcinogenic PAH."

Directly related news brief:
Fifteen cigarettes: all it takes to harm genes...

Reference: Study finds cigarette smoking causes genetic damage within minutes, Linda Shrieves, The Orlando Sentinel, Fla., 1/17/2011.