Although lung cancer has, in general, a linear dose-response relationship with tobacco use, the risk for cardiovascular disease, which accounts for a significant proportion of tobacco-related illness and death, becomes evident with the consumption of 3 to 5 cigarettes a day. Risk for acute myocardial infarction and coronary heart disease associated with exposure to tobacco smoke appears to be nonlinear at low doses and increases rapidly with relatively small doses, such as those received from environmental tobacco smoke or from smoking just a few cigarettes a day. Even small exposures increase platelet aggregation and induce arterial and hemodynamic changes. Pregnant women who smoke as few as 5 cigarettes a day are more likely to have low-birthweight babies.
Cancer is the leading cause of death among smokers in the United States, with lung cancer responsible for nearly 80% of tobacco-related deaths. However, cardiovascular disease (all forms combined) is the leading cause of all tobacco-related mortality, including both smokers and those exposed to environmental tobacco smoke. Cardiovascular disease is second only to respiratory disease (i.e., chronic bronchitis and emphysema) as the leading cause of tobacco-related morbidity.
2 Cardiovascular disease may be caused by exposure to carbon monoxide and other combustion products, which suggests that any “reduced risk” tobacco product that is ignited and inhaled is unlikely to significantly decrease tobacco-related illness and death from cardiovascular causes.
