How tobacco use affects health among young people

This chapter addresses the adverse health consequences of tobacco use in children and young adults. Although the chapter focuses mainly on childhood to early adulthood, it also briefly covers the prenatal period and examines the adverse effects of smoking before conception as well, although this is not the main focus of this report. Previous Surgeon General reports on tobacco use included evidence of increased risk of specific diseases and other adverse effects of active and passive smoking, with the most recent updates in the 2004, 2006, and 2010 reports (U.S. Department of Health and Human Services [USD HHS] 2004, 2006 , 2010) discussing active smoking, passive smoking and the biological basis of the disease. These reports covered the effects of maternal and paternal smoking on almost all aspects of reproduction and the risk of birth malformations, as well as the increased risk from exposure to secondhand smoke for Sudden Infant Death Syndrome (SIDS), an increased incidence of lower respiratory tract disease and respiratory symptoms, reduced lung growth and asthma (see Tables 2.1a and 2.1b for conclusions from earlier reports). Table 2.1a. Conclusions from previous Surgeon General's reports on the adverse effects of tobacco use and exposure to secondhand smoke in children and young adults. Table 2.1a Conclusions from previous Surgeon General's reports on the adverse effects of tobacco use and exposure to secondhand smoke in children and young adults. Table 2.1b. Level of certainty of causality reported in the 2004 and 2006 Surgeon General's reports. Table 2.1b Level of certainty of causality reported in the 2004 and 2006 Surgeon General's reports. This chapter complements these earlier reports by reviewing the health consequences of active smoking in adolescents and young adults, which is a topic last covered in detail by a report in 1994. This report reached several key conclusions about the adverse effects of smoking on young people in relation to their respiratory and cardiovascular health and, in terms of addiction, noted that: "; among addictive behavior's cigarette smoking is most likely to be demonstrated. People who start smoking at an early age are more likely to develop severe nicotine dependence than those who start at a later age" (USD HHS 1994, p. 41).This chapter revisits the topic of the health consequences of smoking for young people who smoke, reviewing in detail the substantial new evidence and placing it in a life-course perspective. It also includes new information on the onset of nicotine dependence during adolescence and young adulthood, which includes prospectively collected data on dependence trajectories from cohort studies. For young people, especially women, weight considerations play a role in the decision to start smoking and to continue smoking; this issue, which is critical to prevention and cessation efforts, is reviewed in detail in this chapter. Information on the health consequences of smokeless tobacco use has been documented in several previous publications (National Cancer Institute [NCI] 2012).Since the 1994 report, the basis for concern about smoking during adolescence and young adulthood has expanded beyond the immediate health consequences for the young smoker to a deeper understanding of the health consequences of exposure to tobacco smoke throughout the lifespan, including in later life generation. This widespread concern reflects the emerging body of evidence linking risk exposures early in life, even in the prenatal period, to the risk of chronic disease in adulthood. The general hypothesis that has been constructed on the basis of this evidence is often  called the "developmental origins of adult disease" hypothesis or the "Barker" hypothesis, in reference to David Barker, who documented links between nutrition in early life and subsequent risk of cardiovascular disease (Barker 2004; de Boo and Harding 2006). Human research relevant to this hypothesis comes largely from epidemiological studies that have linked nutrition in early life with subsequent risk of hypertension and other cardiovascular diseases (Huxley et al. 2000; Barker et al. 2005; de Boo and Harding 2006). . There is also relevant experimental research (Nuyt  2008). Proposed underlying mechanisms highlight genetic and epigenetic changes that could have lasting consequences throughout life (Young  2001;  Gicqueletal. 2008). Even before conception, the sperm and oocytes of prospective parents who smoke are exposed to DNA-damaging components of tobacco smoke (USDHHS 2004); the fetus of a mother who smokes or is exposed to secondhand smoke will be exposed to these harmful materials, most often resulting in reduced birth weight (USDHHS 2004, 2006). However, the molecular changes resulting from these early exposures to tobacco smoke have so far been little investigated. However, one recent study demonstrated epigenetic changes in children with in utero exposure to maternal smoking (Breton et al. 2009), a finding consistent with one proposed mechanism of long-term consequences of early-life exposure. Thus, given the numerous known carcinogens and toxins present in tobacco smoke and the known mechanism by which they cause disease, the developmental origin of disease in adults is a critical concept to consider when addressing youth tobacco use.