in their lifetime. Among twelfth graders, 68 percent have had sexual intercourse, and 27 percent of them have had four or more sexual partners in their lifetime.
In addition, health-compromising behaviors frequently tend to occur in clusters; individuals engaging in one type of high-risk behavior also tend to engage in other types of high-risk behaviors (Donovan and Jessor, 1985; Donovan et al., 1988; National Research Council, 1993; Resnicow et al., 1995). Those who smoke are also more likely drink alcohol, drive after drinking, and have unprotected sexual intercourse. Dryfoos estimated that 10 percent of adolescents are at very high risk for dropping out of school because of engaging in a variety of risky behaviors, an additional 15 percent are at high risk, and 25 percent are at moderate risk (Dryfoos, 1990).
Beyond these major risk areas, adolescents also engage in significant health-compromising practices that endanger health over the long term into adulthood. The CDC's Youth Risk Behavior Survey found that 30.5 percent of high school students smoke cigarettes, only 15.4 percent eat five or more servings of fruits and vegetables per day, and only 34.3 percent attend physical education class daily. The major causes of chronic disease and death among adults—cancer, heart disease, injury, stroke, and liver and lung disease—are influenced by health behaviors and lifestyles established during childhood and youth (U.S. Department of Health and Human Services, 1991).
In 1979, the U.S. Public Health Service identified the four major factors leading to early illness or death and the extent of each contribution: heredity (20 percent), environment (20 percent), inadequate health care delivery system (10 percent), and an unhealthy lifestyle (50 percent) (U.S. Department of Health and Human Services, 1979). Studies by the U.S. Department of Health and Human Services have shown that 99 percent of health expenditures go to medical treatment and only 1 percent goes to population-wide public health prevention strategies. However, estimates predict that medical treatment can prevent only 10 percent of our nation's premature deaths, whereas population-wide public health approaches have the potential to prevent 70 percent of early deaths (U.S. Department of Health and Human Services, 1993).5 The debate surrounding the reform of health care delivery systems would be well advised to consider the fact that cost containment might be achieved by shifting the focus from medical care financing to an emphasis on illness and accident prevention.