Is the smell of cigarettes dangerous?

Old tobacco smoke is also harmful

The fact that secondhand smoke is harmful to health is nothing new. But now there is evidence that even “third-hand smoke” could be harmful. Because when cigarette smoke reacts with chemical components of the room air or surfaces, a potentially carcinogenic substance is created, as US researchers have discovered. This connection with the abbreviation NNA causes DNA damage in cell cultures. The researchers warn that contact with this smoke pollutant could increase the risk of cancer in the long term, especially in children.

Who does not know this: You enter an apartment or a hotel room in which people have smoked frequently, and with the first breath this becomes noticeable in an unpleasantly stale tobacco smell. The smoke hangs in curtains, sofa covers and even in clothes after spending an evening in a smoky environment. For a long time this smell of smoke was considered annoying at worst. But a few years ago researchers found out that some of the more than 4,000 ingredients in tobacco smoke not only stay in the air for a long time - they also react there with other air pollutants such as ozone or nitrogen oxides. However, this creates new chemical compounds that can also be harmful to health and that are deposited in furniture and other objects as “third-hand smoke”.

A special substance derived from smoke could prove to be particularly dangerous, as Bo Hang from the Lawrence Berkeley National Laboratory (LBNL) and his colleagues have now demonstrated. This is a tobacco-specific nitrosamine, or NNA for short, which is produced from the reaction of nicotine with nitrogen compounds. “This substance is missing in fresh tobacco smoke,” explain the researchers. In their experiments, they tested how the NNA affects human cells in cell culture. To do this, they added the dissolved substance to the cells in a concentration of 0.01 to 100 millimoles for 24 hours - these doses are not considered to be acutely toxic to cells, as the scientists emphasize. With the help of various analysis methods such as liquid chromatography, mass spectrometry and magnetic resonance imaging, they then examined the genetic material in the cells treated in this way.

Lumps of genetic material

The result: The NNA had attached to the DNA of the cells and formed lumpy appendages there. Such attachments are typical of many carcinogenic and cell-killing substances, as the researchers report. In animal experiments, for example, such clumps are used as biomarkers for previous exposure to a carcinogen. Further analysis revealed that the chemical from tobacco smoke also caused breaks in the genetic material. Such DNA breaks can disrupt important control mechanisms of the cell and thus lead to degeneration and thus cancer.

"Together, these results provide evidence that NNA can damage DNA," says Hang. This substance could therefore contribute to the harmful and carcinogenic effects of third-party smoke. Animal experiments still have to prove the effect on living organisms, but the researchers still consider their results to be meaningful enough - also because the NNA behaves very similarly to known carcinogens from smoke.

According to the researcher, young children could be most at risk from the smoke residues: They crawl around on the floor and put their hands or objects in their mouths. They can come into contact with these chemicals and absorb parts of them. Because of their small size and early stage of development, they are particularly susceptible to environmental toxins, as Hang emphasizes. He therefore urgently recommends parents not to smoke in the apartment and not to let their children play in smoky rooms. If a room is already contaminated by old tobacco smoke, all that helps is repainting, vacuuming and, best of all, washing or renewing all covers and curtains - a thorough spring cleaning.

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© Wissenschaft.de - Nadja Podbregar
March 16, 2014