Unpublished Tobacco Company Papers Show Toxicity Of Secondhand Smoke Increases Over Time
UC San Francisco - Unpublished research papers from Philip Morris Tobacco Company show that the toxicity of sidestream cigarette smoke, the primary constituent of secondhand smoke, increases over time. To find possible reasons that would explain the increase in sidestream smoke toxicity over time, researchers analyzed unpublished research reports from Philip Morris Co. using internal tobacco industry documents now available at the University of California San Francisco Legacy Tobacco Documents Library and other Web sites.
The unpublished research from Philip Morris Tobacco Company shows that 4-(methylnitrosamino)-I-(3-pyridyl)-1-butanone (NNK), a highly carcinogenic tobacco-specific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)