Sources of Tobacco Smoke Exposure and Their Associations With Serum Cotinine Levels Among US Children and Adolescents

Abstract Introduction We assessed tobacco smoke exposure (TSE) levels based on private and public locations of TSE according to race and ethnicity among US school-aged children ages 6–11 years and adolescents ages 12–17 years. Aims and Methods Data were from 5296 children and adolescents who participated in the National Health and Nutrition Examination Survey (NHANES) 2013–2018. Racial and ethnic groups were non-Hispanic white, black, other or multiracial, and Hispanic. NHANES assessed serum cotinine and the following TSE locations: homes and whether smokers did not smoke indoors (home thirdhand smoke [THS] exposure proxy) or smoked indoors (secondhand [SHS] and THS exposure proxy), cars, in other homes, restaurants, or any other indoor area. We used stratified weighted linear regression models by racial and ethnic groups and assessed the variance in cotinine levels explained by each location within each age group. Results Among 6–11-year-olds, exposure to home THS only and home SHS + THS predicted higher log-cotinine among all racial and ethnic groups. Non-Hispanic white children exposed to car TSE had higher log-cotinine (β = 1.64, 95% confidence interval [CI] = 0.91% to 2.37%) compared to those unexposed. Non-Hispanic other/multiracial children exposed to restaurant TSE had higher log-cotinine (β = 1.13, 95% CI = 0.23% to 2.03%) compared to those unexposed. Among 12–17-year-olds, home SHS + THS exposure predicted higher log-cotinine among all racial and ethnic groups, except for non-Hispanic black adolescents. Car TSE predicted higher log-cotinine among all racial and ethnic groups. Non-Hispanic black adolescents with TSE in another indoor area had higher log-cotinine (β = 2.84, 95% CI = 0.85% to 4.83%) compared to those unexposed. Conclusions TSE location was uniquely associated with cotinine levels by race and ethnicity. Smoke-free home and car legislation are needed to reduce TSE among children and adolescents of all racial and ethnic backgrounds. Implications Racial and ethnic disparities in TSE trends have remained stable among US children and adolescents over time. This study’s results indicate that TSE locations differentially contribute to biochemically measured TSE within racial and ethnic groups. Home TSE significantly contributed to cotinine levels among school-aged children 6–11 years old, and car TSE significantly contributed to cotinine levels among adolescents 12–17 years old. Racial and ethnic differences in locations of TSE were observe