By Noy Birger and Celeste Chen
You know that smoking and being exposed to other people’s cigarette smoke (second-hand smoke) is dangerous, but did you know that residue from cigarette smoke, which remains on just about every surface exposed to that smoke, is also harmful? This is called third-hand smoke.
Third-hand smoke or smoke residue clings to hair and fabrics, including clothing, carpets, drapes, and furniture upholstery.[end Kern JA. Thirdhand smoke another danger. Mayo Clinic Quit Smoking Blog. March 24, 2009. <http://www.mayoclinic.com/health/thirdhand-smoke/MY00591>] The residue reacts with other chemicals and materials in the air, combining to form substances that cause cancer[end Sleiman M, Gundel LA, Pankow JF, Peyton J, Singer BC, Destaillats H. Formation of carcinogens indoors by surface-mediated reactions of nicotine with nitrous acid, leading to potential thirdhand smoke hazards. Proceedings of the National Academy of Sciences. January 6, 2010. <www.pnas.org/cgi/doi/10.1073/pnas.0912820107>] This toxic mix is then breathed in or absorbed through the skin.
One particular chemical found in third-hand smoke, NNA, has been scrutinized because it can directly interact with and damage DNA, possibly paving the way for cancer to grow. Researchers believe that NNA behaves similarly to a byproduct of nicotine called NNK, which has long been known to cause cancer.
In a 2014 study, researchers confirmed that NNA not only breaks up DNA just like NNK does, but also attaches itself to DNA. By breaking up and attaching to DNA, NNA is able to produce cells that grow when they shouldn’t, creating tumors and causing damaging genetic mutations.[end American Chemical Society (ACS). “Major ‘third-hand smoke’ compound causes DNA damage and potentially cancer.” ScienceDaily. ScienceDaily, 16 March 2014. www.sciencedaily.com/releases/2014/03/140316203156.htm.]
Third hand smoke is sneaky
Many public buildings ban indoor smoking, and the majority of people who smoke are aware of the health risks–to them and everyone around them–and therefore confine their smoking to outdoors, away from children and non-smokers. But even after the cigarette has been put out, you can carry dangerous nicotine residue back inside on your hair and clothes, and consequently put others at risk of developing cancer.1
Children are particularly vulnerable. Like adults, they can absorb the tar and nicotine leftovers through their skin. The effect on children is greater because they are smaller and still developing. Also, children are more likely to put their residue-covered hands on their nose or in their mouth.[end Winickoff JP, Friebely J, Tanski SE, Sherrod C, Matt GE, Hovell MF, et. al. Beliefs About the Health Effects of “Thirdhand” Smoke and Home Smoking Bans. Pediatrics. (123.1)74-79] Chemicals such as NNA that are produced when smoke residue mixes with chemicals in the air can cause developmental delays in children. 1 Parents should know that if they smoke in the car, their children can absorb the cancer-causing chemicals from the car upholstery, even if the children weren’t inside the car when the parent was smoking
Third-hand smoke is a new health concern. While we know that the residue combines with the air and other pollutants, like car exhaust fumes,[end Ballantyne C, What is third-hand smoke? Is it hazardous? Scientific American. January 6, 2009. < http://www.scientificamerican.com/article.cfm?id=what-is-third-hand-smoke >] to make a cancer-causing substance, we don’t yet know for certain that it causes cancer in humans and if so, how much exposure is dangerous. Figuring out the answer will be challenging, because most people exposed to third-hand smoke are also exposed to second-hand smoke. We know that non-smokers develop lung cancer, for example, but we usually don’t know if a non-smoker developed cancer because he or she was exposed to third-hand smoke, or for other reasons unrelated to smoking.
Smokers with children or who live with non-smokers should never smoke inside the home or in their car, and clothing worn while smoking should be washed as soon as possible. If you smell cigarette smoke in a place or on someone, it means you are being exposed to third-hand smoke. An expert on helping people quit smoking recommends that after quitting, people should thoroughly clean their homes, wash or dry clean clothing, and vacuum their cars to remove the dangerous smoke leftovers.2 Ideally, it would be best to replace furnishings that may have absorbed the chemicals from third-hand smoke, such as sofas, and re-carpet floors, re-seal and re-paint walls, and replace contaminated wallboard. Even if a smoker hasn’t quit yet, it’s a good idea to vacuum and wash clothes, curtains and bedding regularly to reduce their and their loved ones’ exposure to the dangerous chemicals that form when smoke residue mixes with the air. 3