Leftover cigarette smoke that clings on to walls, furniture and toys may be a threat to young children. Such "third-hand smoke" may damage DNA and cause cancer, says a study.

 

 Research suggests that "third-hand smoke" could pose a far more serious threat, especially to young children who put toys and other smoke-affected items into their mouths.

 

 Scientists reported that one of the tobacco-specific nitrosamines newly formed in "third-hand smoke" damages DNA and could potentially cause cancer. Their talk was one of more than 10,000 presentations at the 247th National Meeting & Exposition of the American Chemical Society (ACS) in Dallas this week.

 

 Bo Hang, Ph.D., who presented the research, said that although the idea of third-hand smoke made its debut in research circles just a few years ago in 2009, evidence already strongly suggests it could threaten human health. "The best argument for instituting a ban on smoking indoors is actually third-hand smoke," said Bo, a scientist at Lawrence Berkeley National Laboratory (LBNL).

 

 Researchers have found that many of the more than 4,000 compounds in second-hand smoke, which wafts through the air as a cigarette is smoked, can linger indoors long after a cigarette is stubbed out.

 

 Based on studies led by Hugo Destaillats, also at LBNL, these substances can go on to react with indoor pollutants such as ozone and nitrous acid, creating brand-new compounds, some of which may be carcinogenic, reported Science Daily.

 

 One of those compounds goes by the acronym NNA. Bo's research has shown that NNA, a tobacco-specific nitrosamine, locks onto DNA to form a bulky adduct (a piece of DNA bound to a cancer-causing chemical), as well as other adducts, in lab test tubes.

 

  Other large compounds that attach to DNA tend to cause genetic mutations. NNA also breaks the DNA about as often as a related compound called NNK, which is a well-studied byproduct of nicotine and a known potent carcinogen.

 

 This kind of DNA damage can lead to uncontrolled cell growth and the formation of cancerous tumors.