Within minutes of inhaling the contents of a lit cigarette, genetic damage starts to occur – it does not take days or years, researchers from the University of Minnesota revealed in Chemical Research in Toxicology. The authors say that their study is the first to explain how specific substances in tobacco smoke cause cancer-associated DNA damage.
Stephen S. Hecht, Ph.D., and team explain that lung cancer kills approximately 3,000 people daily. The vast majority of them die prematurely because of smoking, which is also linked to several additional cancers, as well as cardiovascular and respiratory diseases, erectile dysfunction and other illnesses.
Previous studies have shown that PAHs (polycyclic aromatic hydrocarbons), which are present in tobacco smoke, are key triggers in the development of lung cancer. However, until this latest study, nobody could define exactly how these PAHs damage human genes.
The researchers added phenanthrene – a labeled PAH – to cigarettes and tracked its path with the help of 12 volunteer smokers.
The authors wrote:
“This study used a unique approach employing a stable isotope derivative of phenanthrene, the simplest PAH with a bay region, a feature closely associated with PAH carcinogenicity.”
They discovered that phenanthrene rapidly forms a toxic substance in the blood which trashes DNA, resulting in cancer-causing mutations.
The scientists were surprised at how quickly this substance reached maximum levels – about fifteen to thirty minutes after the smokers had put out their cigarettes. They explained that the effect was as fast as injecting the substance directly into the bloodstream.
The authors wrote:
“Levels of [D10]PheT in plasma of all subjects were maximal at the earliest time points examined, 15-30 min after smoking the cigarette containing [D10]phenanthrene, and decreased thereafter.”
Hecht wrote:
“This study is unique. 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.”
“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
Chem. Res. Toxicol., DOI: 10.1021/tx100345x
Written by Christian Nordqvist