New Research Points to Threat in Thirdhand Tobacco Smoke

Nicotine on surfaces, nitrous oxide in air react to form carcinogenic tobacco-specific nitrosamines

TUESDAY, Feb. 9 (HealthDay News) -- Nicotine left on surfaces from tobacco smoke can combine with ambient nitrous oxide to create carcinogens, raising new concern over the health effects of so-called thirdhand smoke, according to research published online Feb. 8 in the Proceedings of the National Academy of Sciences.

Mohamad Sleiman, of the Lawrence Berkeley National Laboratory in California, and colleagues found appreciable levels of two tobacco-specific nitrosamines (TSNAs), created by the reaction of nicotine and gaseous nitrous oxide, on surfaces in a vehicle driven by a heavy smoker. One of these -- 4-(methylnitrosamino)-1-(3-pyridil)-1-butanone -- is known to be a strong carcinogen.

The authors discuss further experiments in which they exposed a cellulose substrate to vaporized nicotine followed by nitrous oxide. After three hours of exposure to nitrous oxide, surface concentrations of TSNA increased greater than 10-fold. The main routes of exposure to TSNAs are likely skin contact with contaminated surfaces and inhalation or ingestion of contaminated dust, the authors write. Infants may be at higher risk due to their low body weight, high respiration rate, and high level of dust ingestion.

"Various mitigation and remediation approaches can be considered to limit the impact of these carcinogenic pollutants indoors. Implementation of 100 percent smoke-free environments in public places and self-restrictions in residences and automobiles are the most effective tobacco control measures, through elimination of the primary pollution source," the authors write.

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