Gaining on Secondhand Smoke, But Thirdhand Now Feared
This third time is not a charm: Residual nicotine from tobacco smoke that clings to indoor surfaces reacts with the common air pollutant nitrous acid to form dangerous carcinogens.
Even as HHS units report a welcome drop in the number of states that preempted local smoking bans in restaurants, private work sites, and government work sites, a new study identified hazards in thirdhand smoke: Residual nicotine from tobacco smoke that is sorbed to indoor surfaces and reacts with ambient nitrous acid forms harmful carcinogens, a study led by Lawrence Berkeley National Laboratory researchers showed. Team members work at the lab's Indoor Environment Department, the Portland State University Department of Chemistry, the University of California San Francisco departments of Medicine and Psychiatry, and the Arizona State University School of Sustainable Engineering and the Built Environment. They found that residual nicotine from tobacco smoke clinging to surfaces inside a smoker's vehicle reacts with ambient nitrous acid to form carcinogenic tobacco-specific nitrosamines (TSNAs). Lab testing of cellulose as a model indoor material showed a tenfold increase of surface-bound TSNAs when sorbed secondhand smoke was exposed to 60 parts per billion of nitrous acid for three hours.
"The burning of tobacco releases nicotine in the form of a vapor that adsorbs strongly onto indoor surfaces, such as walls, floors, carpeting, drapes, and furniture. Nicotine can persist on those materials for days, weeks, and even months," said Hugo Destaillats, a chemist with the Berkeley Indoor Environment Department. "TSNAs are among the most broadly acting and potent carcinogens present in unburned tobacco and tobacco smoke."
They found TSNAs form fairly quickly, with up to 0.4 percent conversion of nicotine within the first hour. "Given the rapid sorption and persistence of high levels of nicotine on indoor surfaces, including clothing and human skin, our findings indicate that thirdhand smoke represents an unappreciated health hazard through dermal exposure, dust inhalation, and ingestion," said Mohamad Sleiman, the study's lead author, who works at the Berkeley lab.
The news about progress against secondhand smoke comes from CDC's MMWR publication. From Jan. 1, 2005, to Dec. 31, 2009, the number of U.S. states with laws preempting local smoking bans covering restaurants, private work sites, and government work sites declined from 19 to 12. Six states (Illinois, Iowa, Nevada, New Jersey, Oregon, and South Carolina) removed preemptions in all three settings during this period.