24 January 2011
ByAppeared in BioNews 592
A team of US scientists has studied the immediate consequences of cigarette smoking in humans and found cigarette smoke potentially affects a smoker's genes within a timescale of minutes.
Twelve regular smokers participated in the study and were given specifically prepared cigarettes to which a non-carcinogenic substance, phenanthrene, had been added. The results showed that the highest concentration of the carcinogenic (cancer-causing) chemicals is found only 15 to 30 minutes after smoke inhalation.
Carcinogenic substances known as polycyclic aromatic hydrocarbons (PAH) have been associated with the development of lung cancer in smokers and are formed within 15 minutes after smoking a cigarette.
PAH are modified in the body resulting in the formation of another chemical known to react with a person's DNA causing mutations and initiating carcinogenic processes. Blood samples of all smokers in the study showed increased levels of this chemical only 15 to 30 minutes after the cigarette has been smoked.
Professor Stephen Hecht from the University of Minnesota, senior author of the research, emphasised the uniqueness of the study: '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'.
Whereas the long-term effects of smoking are well-studied and known, its short-term consequences have so far been predominantly studied in animals. There are, however, some limitations to the findings. The study did not compare the results to a control group of non-smokers but only sampled regular smokers consuming at least ten cigarettes a day. For ethical reasons, the authors also used a non-carcinogenic PAH, which might show a different metabolism than other carcinogenic PAHs.
The study was published in the journal Chemical Research in Toxicology and was funded by the US National Cancer Institute.