Scientists now reveal dangers of third-hand smoke

Nicotine in third-hand smoke, the residue that clings to virtually all surfaces long after a cigarette has been snuffed, reacts with the common indoor air pollutant nitrous acid to produce dangerous carcinogens.

This new potential health hazard was revealed in a multi-institutional study led by researchers with the Lawrence Berkeley National Laboratory (Berkeley Lab).

"The burning of tobacco releases nicotine in the form of a vapour that adsorbs strongly onto indoor surfaces, such as walls, floors, carpeting, drapes and furniture," says Hugo Destaillats, chemist with Berkeley Lab's Environmental Energy Technologies Division.

"Nicotine can persist on those materials for days, weeks and even months. Our study shows that when this residual nicotine reacts with ambient nitrous acid it forms carcinogenic tobacco-specific nitrosamines or TSNAs."

"TSNAs are among the most broadly acting and potent carcinogens present in unburnt tobacco and tobacco smoke," says Destaillats, study co-author.

Since the most likely human exposure to these TSNAs is through either inhalation of dust or the contact of skin with carpet or clothes, third-hand smoke would seem to pose the greatest hazard to infants and toddlers, said a Berkeley release.

The study's findings indicate that opening a window or deploying a fan to ventilate the room while a cigarette burns does not eliminate the hazard of third-hand smoke. Smoking outdoors is not much of an improvement, study authors explain.

The study was published in the Proceedings of the National Academy of Sciences (PNAS).

Last updated on Feb 9^th, 2010 at 14:24 pm IST--IANS