Formation of carcinogens indoors by surface-mediated reactions of nicotine with nitrous acid, leading to potential thirdhand smoke hazards

• Published in: Proceedings of the National Academy of Sciences - PNAS 2010-04, Vol.107 (15), p.6576-6581
• Main Authors: Sleiman, Mohamad, Gundel, Lara A, Pankow, James F, Jacob, Peyton III, Singer, Brett C, Destaillats, Hugo
• Format: Article
• Language: English
• Subjects: Adsorption; ATMOSPHERIC CHEMISTRY SPECIAL FEATURE; Automobiles; Carcinogens; Carcinogens - chemistry; Cellulose - chemistry; Chemical hazards; Chemistry - methods; Chromatography, Gas - methods; Cigarette smoking; Cigarettes; Desorption; Gases; Hazardous materials; Health hazards; Humans; Kinetics; Lung cancer; Mass spectroscopy; Nicotine; Nicotine - chemistry; Nitrogen Oxides - chemistry; Nitrous Acid - chemistry; Physical Sciences; Secondhand smoke; Sorption; Surface Properties; Tandem Mass Spectrometry - methods; Tobacco Smoke Pollution; Tobacco smoking; Vehicles
• ISSN: 0027-8424; 1091-6490; 1091-6490
• DOI: 10.1073/pnas.0912820107

This study shows that residual nicotine from tobacco smoke sorbed to indoor surfaces reacts with ambient nitrous acid (HONO) to form carcinogenic tobacco-specific nitrosamines (TSNAs). Substantial levels of TSNAs were measured on surfaces inside a smoker's vehicle. Laboratory experiments using cellulose as a model indoor material yielded a > 10-fold increase of surface-bound TSNAs when sorbed secondhand smoke was exposed to 60 ppbv HONO for 3 hours. In both cases we identified 1-(N-methyl-N-nitrosamino)-1-(3-pyridinyl)-4-butanal, a TSNA absent in freshly emitted tobacco smoke, as the major product. The potent carcinogens 4-(methylnitrosamino)-1-(3-pyridinyl)-1-butanone and N-nitroso nornicotine were also detected. Time-course measurements revealed fast TSNA formation, with up to 0.4% conversion of nicotine. Given the rapid sorption and persistence of high levels of nicotine on indoor surfaces--including clothing and human skin--this recently identified process represents an unappreciated health hazard through dermal exposure, dust inhalation, and ingestion. These findings raise concerns about exposures to the tobacco smoke residue that has been recently dubbed "thirdhand smoke." Our work highlights the importance of reactions at indoor interfaces, particularly those involving amines and NOx/HONO cycling, with potential health impacts.