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Warning over dangers of third hand smoke

Researchers advise replacing furnishings previously exposed to heavy smoking

OnMedica Staff

Tuesday, 09 February 2010

The lingering smell of tobacco smoke in houses and cars is not only unpleasant it is hazardous to health, research published in the Proceedings of the National Academy of Sciences has found.

Nicotine residue from tobacco smoke clings to virtually all surfaces long after a cigarette has been extinguished and reacts with the common indoor air pollutant nitrous acid to produce dangerous carcinogens.

In tests of cellulose surfaces contaminated with nicotine residues from third-hand smoke, researchers at Berkeley Lab in the US found that levels of newly formed TSNAs rose tenfold following a three hour exposure to nitrous acid. TSNAs are potent carcinogens.

“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. 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,” said Hugo Destaillats, a chemist at Berkeley Lab. “TSNAs are among the most broadly acting and potent carcinogens present in unburned tobacco and tobacco smoke.”

The study’s findings indicate that opening a window or using a fan to ventilate the room while a cigarette burns does not eliminate the hazard of third-hand smoke. Smoking outdoors also does not prevent it.

Lara Gundel, a chemist at Berkeley Lab, said: “Smoking outside is better than smoking indoors but nicotine residues will stick to a smoker’s skin and clothing. Those residues follow a smoker back inside and get spread everywhere. The biggest risk is to young children. Dermal uptake of the nicotine through a child’s skin is likely to occur when the smoker returns and if nitrous acid is in the air, which it usually is, then TSNAs will be formed.”

The researchers recommended implementing 100% smoke-free environments in public places and self-restrictions in homes and cars to prevent the dangers of third hand smoke. In buildings where substantial smoking has occurred, replacing nicotine-laden furnishings, carpets and wallboard might significantly reduce exposures, they said.

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