We know firsthand smoke is bad, and we know secondhand smoke is also bad. But now, researchers have found that thirdhand smoke -- the surface-clinging residue left over from secondhand smoke -- can also cause damage to our DNA.
"This is the very first study to find that thirdhand smoke is mutagenic," study researcher Lara Gundel, a scientist at the Lawrence Berkeley National laboratory, said in a statement. "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 study, published in the journal Mutagenesis, doesn't just show that thirdhand smoke can harm cells -- it also shows that the harm it can cause could become worse with time.
Researchers put paper strips in chambers with smoke; one chamber exposed the paper strips to the equivalent amount of smoke and chemicals that comes from smoking five cigarettes in 20 minutes. The other chamber exposed the paper strips to cigarette smoke for a total of 258 hours as well as ventilated air for 35 hours, spread out over 196 days.
The researchers found higher concentrations of the toxic compounds in cigarette smoke on the strips of paper that were "chronically" exposed to smoke, compared with the strips of paper "acutely" exposed to smoke.
Then, researchers took the compounds from the paper and exposed them to human cells in a culture for a full 24 hours. They found that the thirdhand smoke led to oxidative DNA damage, as well as DNA strand breaks.
"The findings of this study demonstrate for the first time that exposure to THS [thirdhand smoke] is genotoxic in human cell lines," the researchers wrote in the study. They explained that genotoxicity is a known player in the development of cancer and other disease as a result of smoke.
HuffPost Green reported in 2011 about Indiana University Health's decision to change its policy on employee smoking during the workday because of thirdhand smoke: instead of smoking off-campus during the workday, they are not allowed to smoke at all because the chemicals from the cigarette smoke still clings to their clothing and bodies.
For more on thirdhand smoke and its potential dangers, click over to HuffPost Green's article.