Leftover cigarette smoke clings to walls and furniture and could pose a far more serious threat, according to a presentation at the National Meeting&Exposition of the American Chemical Society (ACS) which says that one compound from this "third-hand smoke" can damage DNA and and even potentially cause cancer.
Bo Hang, Ph.D., of Lawrence Berkeley National Laboratory noted that the idea of third-hand smoke only come into existence in 2009, But that evidence already suggests it could threaten human health. In test tubes, anyway.
"The best argument for instituting a ban on smoking indoors is actually third-hand smoke," said Hang.
The hypothesis behind third-hand smoke is that some of the more than 4,000 compounds in cigarette smoke can linger long after the cigarette is extinguished. Based on studies led by Hugo Destaillats, Ph.D., 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.
One of those compounds goes by the acronym NNA. Hang says 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 laboratory 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.
Just as it took years to establish the cancer-causing effects of smoke that is inhaled as a person breathes in directly from the cigarette, making the connection between third-hand smoke or NNA and cancer could take a long time. There are no deaths attributed to second-hand smoke so the connection to third-hand smoke has only been embraced by activists who want to ban smoking altogether.
After third hand smoke was created in 2009, a California consortium was created to find evidence for it in 2010. That consortium helped fund this work on NNA-induced DNA damage, which hopes to eventually be used as biomarkers to identify people who have been exposed to third-hand smoke.
Although many public places have banned smoking, people can still smoke in most rental apartments and private residences and Hang believes that should change. As of 2011, CDC statistics say nearly 34 million American adults still report smoking cigarettes and the numbers in Europe and Asia are even higher.