Smoking is a widely acknowledged danger to human health. Tobacco smoke causes or exacerbates conditions including asthma, respiratory infections, and cancer. Its not only the smoker or the second hand smokers are adversely affected due to smoking but also the third hand smoking or the smokers who inhale the chemicals released after the smoker has smoked are equally in danger.
Think of a situation when you have walked into a restaurant or elevator or a closed room and smelled old cigarette smoke? While the last smoker may have left the room hours or even days ago, the lingering odors—resulting from noxious residue that clings to walls, carpets, furniture, or dust particles—are there to harm you. Now you are a third hand smoker.
Most of the smokers will agree that second hand smoking is dangerous so they don’t smoke when their kids are present. But if, for example, they stop smoking at 2 p.m. and the kids come home at 4 p.m., studies show that up to 60 percent of the harm from inhaling thirdhand smoke remains.
A study led by researchers from Lawrence Berkeley National Laboratory has found for the first time that thirdhand smoke—the noxious residue that clings to virtually all surfaces long after the second hand smoke from a cigarette has cleared out—causes significant genetic damage in human cells.
“This is the very first study to find that thirdhand smoke is mutagenic,” said Lara Gundel, a Berkeley Lab scientist and co-author of the study. “Tobacco-specific nitrosamines, some of the chemical compounds in thirdhand smoke, are among the most potent carcinogens there are. They stay on surfaces, and when those surfaces are clothing or carpets, the danger to children is especially serious.”
The 2010 studies from Berkeley Lab found that residual nicotine can react with ozone and nitrous acid—both common indoor air pollutants—to form hazardous agents. When nicotine in thirdhand smoke reacts with nitrous acid it undergoes a chemical transformation and forms carcinogenic tobacco-specific nitrosamines, such as NNA, NNK and NNN. Nicotine can react with ozone to form ultrafine particles, which can carry harmful chemicals and pass through human tissue. Humans can be exposed to thirdhand smoke through inhalation, ingestion or skin contact.
Thirdhand smoke is particularly insidious because it is extremely difficult to eradicate. Studies have found that it can still be detected in dust and surfaces of apartments more than two months after smokers moved out. Common cleaning methods such as vacuuming, wiping and ventilation have not proven effective in lowering nicotine contamination. “You can do some things to reduce the odors, but it’s very difficult to really clean it completely,” said Destaillats. “The best solution is to substitute materials, such as change the carpet, repaint.”
Now the new study suggests thirdhand smoke could become more harmful over time. To generate the samples, the researchers put paper strips in smoking chambers. The acute samples, generated at Berkeley Lab, were exposed to five cigarettes smoked in about 20 minutes, and the chronic samples, generated at UCSF, were exposed to cigarette smoke for 258 hours over 196 days. During that time, the chamber was also ventilated for about 35 hours.
The researchers found that the concentrations of more than half of the compounds studied were higher in the chronic samples than in the acute. They also found higher levels of DNA damage caused by the chronic samples. “The cumulative effect of thirdhand smoke is quite significant,” Gundel said. “The findings suggest the materials could be getting more toxic with time.”