Evaluation of Tobacco Smoke and Diet as Sources of Exposure to Two Heterocyclic Aromatic Amines for the US Population: NHANES 2013-2014

Background: Heterocyclic aromatic amines (HAA) are a group of hazardous substances produced during combustion of tobacco or high-temperature cooking of meats. 2-Amino-9H-pyrido[2,3-b]indole (A alpha C) is a major carcinogenic HAA in tobacco smoke. Methods: Urinary A alpha C, used as a marker of A alpha C exposure, was analyzed on spot urine samples from adult participants of the 2013-2014 cycle of the National Health and Nutrition Examination Survey (N = 1,792). A alpha C was measured using isotope-dilution liquid chromatography-tandem mass spectrometry. Exclusive combusted tobacco smokers were differentiated from nonusers of tobacco products through both self-report and serum cotinine data. Results: Among exclusive smokers, sample-weighted median urinary A alpha C was 40 times higher than nonusers. Sample-weighted regression models showed that urinary A alpha C increased significantly with serum cotinine among both exclusive tobacco users and nonusers with secondhand smoke exposure. Among nonusers, eating beef cooked at high temperature was associated with a significant increase in urinary A alpha C, whereas consuming vegetables was associated with decreased A alpha C. In addition, smoking one-half pack of cigarettes per day was associated with a significant increase of 23.6 pg A alpha C/mL calculated at geometric mean of A alpha C, controlling for potential confounders. In comparison, increase in A alpha C attributable to consuming the 99th percentile of beef cooked at high temperature was 0.99 pg A alpha C/mL. Conclusions: Both exclusive smokers and nonusers of tobacco in the general U.S. population are exposed to A alpha C from tobacco smoke, with additional, lesser contributions from certain dietary components. Impact: A alpha C is an important biomarker that is associated with tobacco smoke exposure.