Abstract
Research has shown that the toxicity of sidestream cigarette smoke, the primary constituent of secondhand smoke, increases over time. To find potential mechanisms that would explain the increase in sidestream smoke toxicity over time, we analyzed unpublished research reports from Philip Morris Co. using the internal tobacco industry documents now available at the University of California San Francisco Legacy Tobacco Documents Library and other Web sites. Unpublished research from Philip Morris Tobacco Company shows that 4-(methylnitrosamino)-I-(3-pyridyl)-1-butanone (NNK), a highly carcinogenic tobacco-specific nitrosamine, can form in sidestream cigarette smoke after it has been released into ambient air. In experiments done between 1983 and 1997, Philip Morris scientists measured the concentration of NNK in sidestream smoke in a sealed stainless steel test chamber at initial particle concentrations of 24 mg/m3 over the course of 6 to 18 h. They repeatedly showed that airborne NNK concentrations in sidestream cigarette smoke can increase by 50% to 200% per hour during the first 6 h after cigarettes are extinguished. Two experiments done in a real office showed that NNK concentrations increase for the first 2 h after cigarettes are extinguished. If NNK formation also occurs in the lower smoke concentrations observed in real smoking environments, these results suggest that nitrosation of nicotine and/or nicotine breakdown products in aging secondhand smoke is a significant contributor to nitrosamine exposure in humans. (Cancer Epidemiol Biomarkers Prev 2007;16(8):1547–53)
- nitrosamine
- secondhand cigarette smoke
- environmental tobacco smoke
- sidestream
- NNK
- tobacco-specific nitrosamine
Footnotes
↵4 http://www.beitraege-bti.de, accessed November 10, 2006.
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Grant support: National Cancer Institute grant CA-87472 and the California Tobacco-Related Disease Research Program grant 12FT-0144.
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The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
- Accepted May 17, 2007.
- Received March 7, 2007.
- Revision received May 7, 2007.