increases the risk of invasive pneumococcal disease. Secondhand smoke is associated with aggravation of allergies and asthma and with reduction in pulmonary function.
Parental smoking can cause pneumonia and bronchitis in young children. Exposure appears to interact with acute respiratory infection in the first year of life and increases the incidence of childhood asthma and middle ear infection. It also increases the risk of sudden infant death syndrome (US Surgeon General, 2007). Children born to mothers who smoke or who are exposed to secondhand smoke have reduced lung volumes compared with nonexposed (US Surgeon General, 2007).
The most widely used smokeless-tobacco products in the United States are moist snuff and chewing tobacco. Moist snuff is available both as loose tobacco and in small packets (sachets) that are placed between the lip and the gum. Smokeless tobacco delivers as much nicotine to the user as does smoking but does not expose the user to all the toxicants generated by the combustion of tobacco (Wennmalm et al., 1991). About 3% of American adults use smokeless tobacco; the prevalence is much higher in men (6%) than in women (0.4%) (CDC, 2007).
Smokeless tobacco poses two types of health risks: its constituents directly affect health, and, perhaps more important with respect to disease risk, its use maintains nicotine addiction and promotes continued smoking. For example, some smokers use smokeless tobacco to satisfy their need for nicotine when smoking is restricted but continue to smoke when smoking is permitted.
The direct harm caused by use of smokeless tobacco must be viewed in relation to specific products, which differ markedly in the composition and content of carcinogens and other toxicants. All smokeless tobacco delivers carcinogens, such as tobacco-specific nitrosamines, which are formed from nicotine in the curing process (Hecht, 1998). IARC (2007) finds that there is sufficient evidence that smokeless-tobacco use causes cancers of the oral cavity and pancreas. One study of Swedish men compared those who used snus (moist snuff) with those who had never used any tobacco; snus users had a higher rate of pancreatic cancer (relative risk [RR], 2.0; 95% CI, 1.2–3.3) but not of oral cancer (RR, 0.8; 95% CI, 0.4–1.7) or lung cancer (RR, 0.8; 95% CI, 0.5–1.3) (Luo et al., 2007). A recent systematic review of 11 studies, however, found that smokeless tobacco use was not associated with an increased risk of pancreatic cancer (RR, 1.03; 95% CI, 0.71–1.49) (Sponsiello-Wang et al., 2008). Smokeless tobacco is associated with dental problems, including caries. Smokeless tobacco users are twice as