Concerns are being raised about thirdhand smoke, defined as the residue that clings to surfaces after a cigarette has been extinguished. Nicotine from tobacco smoke sticks to indoor surfaces and reacts with ambient nitrous oxide to form potent carcinogens called tobacco-specific nitrosamines (TSNAs).

“Substantial levels of TSNAs were measured on surfaces inside a smoker’s vehicle,” reported Mohamad Sleiman and colleagues in a study published online ahead of print in Proceedings of the National Academy of Sciences of the United States of America.

Time-course measurements revealed fast TSNA formation —up to 0.4% conversion of nicotine within the first hour. Given the rapid absorption and persistence of high levels of nicotine on indoor surfaces, including clothing and human skin, “Our findings indicate that thirdhand smoke represents an underappreciated health hazard through dermal exposure, dust inhalation, and ingestion,” concluded the researchers.

Another smoking study, this one led by Christopher Lathan, MD, MS, MPH, found that African Americans are more likely than whites to hold mistaken beliefs about lung cancer that could interfere with prevention and treatment (published online ahead of print in the journal Cancer).