Thirdhand Tobacco Smoke
Thirdhand Tobacco Smoke
Background: There is broad consensus regarding the health impact of tobacco use and secondhand smoke exposure, yet considerable ambiguity exists about the nature and consequences of thirdhand smoke (THS).
Objectives: We introduce definitions of THS and THS exposure and review recent findings about constituents, indoor sorption–desorption dynamics, and transformations of THS; distribution and persistence of THS in residential settings; implications for pathways of exposure; potential clinical significance and health effects; and behavioral and policy issues that affect and are affected by THS.
Discussion: Physical and chemical transformations of tobacco smoke pollutants take place over time scales ranging from seconds to months and include the creation of secondary pollutants that in some cases are more toxic (e.g., tobacco-specific nitrosamines). THS persists in real-world residential settings in the air, dust, and surfaces and is associated with elevated levels of nicotine on hands and cotinine in urine of nonsmokers residing in homes previously occupied by smokers. Much still needs to be learned about the chemistry, exposure, toxicology, health risks, and policy implications of THS.
Conclusion: The existing evidence on THS provides strong support for pursuing a programmatic research agenda to close gaps in our current understanding of the chemistry, exposure, toxicology, and health effects of THS, as well as its behavioral, economic, and sociocultural considerations and consequences. Such a research agenda is necessary to illuminate the role of THS in existing and future tobacco control efforts to decrease smoking initiation and smoking levels, to increase cessation attempts and sustained cessation, and to reduce the cumulative effects of tobacco use on morbidity and mortality.
In this article, we aim to clarify ambiguities and misunderstandings in the scientific community regarding thirdhand smoke (THS), also known as residual or aged tobacco smoke. The significance of THS in the broader context of tobacco control efforts and its specific role in causing, contributing, moderating, or mediating tobacco-related illnesses have been questioned. To paraphrase an anonymous reviewer of an earlier manuscript on THS: THS is probably no more than a trivial nuisance, no worse than spilled coffee. This skepticism is in contrast to the positions taken by the public health community on issues of tobacco control in general and involuntary exposure to tobacco smoke in particular. The 2006 U.S. Surgeon General's Report on the health consequences of involuntary exposure to tobacco smoke concluded: "The scientific evidence indicates that there is no risk-free level of exposure to secondhand smoke" (U.S. Department of Health and Human Services 2006). If decades of scientific research support the conclusion that there is no risk-free level of exposure to the potent mixture of carcinogens, irritants, and other toxicants in secondhand smoke (SHS), the composition, prevalence, and distribution of THS and the acute and cumulative exposure to those compounds among nonsmokers should be examined before we declare THS pollution and exposure a mere nuisance. We must better understand the role of THS exposure of people, particularly children, to the components of tobacco smoke. The implications of this exposure for disease mechanisms and their moderators and the THS-related acute and long-term risks of disease and premature mortality must be examined. Finally, we should consider the degree to which such understanding can inform and perhaps transform tobacco control policies, which would allow nonsmokers, their families, and the public to make more informed decisions about living in THS-polluted environments and to help smokers to better understand the risks their smoking brings to others. Perhaps a better understanding of THS and the associated risks to nonsmokers, stricter norms and attitudes, and economic and social contingencies will motivate nonsmokers not to start and prompt addicted smokers to quit. We propose that the "bench to bedside to population" approach of translational research will be useful in guiding research on THS and in fostering translation of findings to protect public health (National Institutes of Health 2009).
We review the emerging evidence on THS and outline the case for an interdisciplinary research effort. The existing evidence provides strong support for pursuing a programmatic research agenda on THS to fill important gaps in our current understanding of the short- and long-term effects of involuntary exposure to tobacco smoke. We begin with brief definitions of THS and THS exposure. We then present a review of recent findings on the chemistry of THS, its persistence in indoor environments, implications for pathways of exposure and health effects, and behavioral and policy issues that affect and are affected by THS. We conclude with recommendations for interdisciplinary research efforts to address the gap in knowledge of the biological mechanisms of toxicity on cellular and molecular levels, as well as relevant behavioral, economic, and sociocultural considerations and consequences.
Abstract and Introduction
Abstract
Background: There is broad consensus regarding the health impact of tobacco use and secondhand smoke exposure, yet considerable ambiguity exists about the nature and consequences of thirdhand smoke (THS).
Objectives: We introduce definitions of THS and THS exposure and review recent findings about constituents, indoor sorption–desorption dynamics, and transformations of THS; distribution and persistence of THS in residential settings; implications for pathways of exposure; potential clinical significance and health effects; and behavioral and policy issues that affect and are affected by THS.
Discussion: Physical and chemical transformations of tobacco smoke pollutants take place over time scales ranging from seconds to months and include the creation of secondary pollutants that in some cases are more toxic (e.g., tobacco-specific nitrosamines). THS persists in real-world residential settings in the air, dust, and surfaces and is associated with elevated levels of nicotine on hands and cotinine in urine of nonsmokers residing in homes previously occupied by smokers. Much still needs to be learned about the chemistry, exposure, toxicology, health risks, and policy implications of THS.
Conclusion: The existing evidence on THS provides strong support for pursuing a programmatic research agenda to close gaps in our current understanding of the chemistry, exposure, toxicology, and health effects of THS, as well as its behavioral, economic, and sociocultural considerations and consequences. Such a research agenda is necessary to illuminate the role of THS in existing and future tobacco control efforts to decrease smoking initiation and smoking levels, to increase cessation attempts and sustained cessation, and to reduce the cumulative effects of tobacco use on morbidity and mortality.
Introduction
In this article, we aim to clarify ambiguities and misunderstandings in the scientific community regarding thirdhand smoke (THS), also known as residual or aged tobacco smoke. The significance of THS in the broader context of tobacco control efforts and its specific role in causing, contributing, moderating, or mediating tobacco-related illnesses have been questioned. To paraphrase an anonymous reviewer of an earlier manuscript on THS: THS is probably no more than a trivial nuisance, no worse than spilled coffee. This skepticism is in contrast to the positions taken by the public health community on issues of tobacco control in general and involuntary exposure to tobacco smoke in particular. The 2006 U.S. Surgeon General's Report on the health consequences of involuntary exposure to tobacco smoke concluded: "The scientific evidence indicates that there is no risk-free level of exposure to secondhand smoke" (U.S. Department of Health and Human Services 2006). If decades of scientific research support the conclusion that there is no risk-free level of exposure to the potent mixture of carcinogens, irritants, and other toxicants in secondhand smoke (SHS), the composition, prevalence, and distribution of THS and the acute and cumulative exposure to those compounds among nonsmokers should be examined before we declare THS pollution and exposure a mere nuisance. We must better understand the role of THS exposure of people, particularly children, to the components of tobacco smoke. The implications of this exposure for disease mechanisms and their moderators and the THS-related acute and long-term risks of disease and premature mortality must be examined. Finally, we should consider the degree to which such understanding can inform and perhaps transform tobacco control policies, which would allow nonsmokers, their families, and the public to make more informed decisions about living in THS-polluted environments and to help smokers to better understand the risks their smoking brings to others. Perhaps a better understanding of THS and the associated risks to nonsmokers, stricter norms and attitudes, and economic and social contingencies will motivate nonsmokers not to start and prompt addicted smokers to quit. We propose that the "bench to bedside to population" approach of translational research will be useful in guiding research on THS and in fostering translation of findings to protect public health (National Institutes of Health 2009).
We review the emerging evidence on THS and outline the case for an interdisciplinary research effort. The existing evidence provides strong support for pursuing a programmatic research agenda on THS to fill important gaps in our current understanding of the short- and long-term effects of involuntary exposure to tobacco smoke. We begin with brief definitions of THS and THS exposure. We then present a review of recent findings on the chemistry of THS, its persistence in indoor environments, implications for pathways of exposure and health effects, and behavioral and policy issues that affect and are affected by THS. We conclude with recommendations for interdisciplinary research efforts to address the gap in knowledge of the biological mechanisms of toxicity on cellular and molecular levels, as well as relevant behavioral, economic, and sociocultural considerations and consequences.