High-stable smokers experienced the most health problems, as measured by number of provider visits for health problems and number of days of illness-related impairment, but only among non-Whites. The observed differences in health outcomes might be attributable to the consequences of smoking, but we cannot rule out the possible influence of third factors associated with both smoking and Trichostatin A mw health, such as heavy drinking, stress, negative affect (Magid, Colder, Stroud, & Nichter, 2009), and other possible health risk behaviors or mental health problems. The finding that race moderated the relationship between smoking trajectory group membership and two health outcomes was unexpected given our low levels of smoking but is consistent with prior findings.

Numerous studies have documented that Blacks are more vulnerable than Whites to the health effects of smoking in terms of slower nicotine metabolism (Perez-Stable, Herrera, Jacob, & Benowitz, 1998), greater susceptibility to nicotine dependence (Luo et al., 2008), and smoking-related lung cancer (Harris, Zang, Anderson, & Wynder, 1993). Future studies with larger samples should investigate whether race differences in the health effects of smoking exist even at low levels of smoking and elucidate the possible mechanisms underlying that association, including the possible role of third factors not measured in this study such as race differences in attitudes about health-promoting behaviors, peer tobacco use, religiosity, social integration, and other risk factors for substance involvement (Juon et al., 2002; Wallace & Muroff, 2002).

Limitations and Strengths Results must be interpreted in light of certain limitations. Self-report data are subject to recall bias, although this was likely minimized by focusing on very recent behavior (i.e., past-month smoking). Generalizability to other settings and geographic areas is unknown, especially given the sample��s homogeneity with respect to neighborhood income. Our income measure was based on participants�� neighborhood of residence immediately prior to college, rather than actual family income, and might not adequately represent socioeconomic status, which is a more complex construct. Past-month smoking might not be representative of smoking patterns throughout the rest of the year, such as weekday�Cweekend differences documented elsewhere (Colder et al., 2006). Although the overall sample size was large (N = 1,253), individual cell sizes for smoking trajectory group comparisons were not sufficient to detect significant differences, especially among nonWhites. Our self-report measures of health outcomes might be confounded by other personal GSK-3 factors such as differences in help-seeking and health-promoting behaviors and attitudes.