Public health authorities worldwide have concluded that exposure to environmental tobacco smoke (ETS) causes diseases, including cancer, in adult nonsmokers. The arylamine, 4-aminobiphenyl (4-ABP), has been identified as a human carcinogen. Some publications have suggested that 4-ABP hemoglobin (4-ABP-Hb) adduct levels in nonsmokers are a result of exposure to ETS, whereas others could not confirm these observations. Toxicokinetic and exposure models proposed in this work are used to estimate the concentration of 4-ABP-Hb adducts resulting from ETS exposure that is based on experimental values for respirable suspended particulates (RSP) concentration. Monte Carlo methods were used to obtain estimates of population distributions of 4-ABP-Hb adduct levels resulting from indoor ETS exposure in homes, workplaces, and hospitality environments. It is found that the mean, median, and 95th percentile 4-ABP-Hb adduct steady-state levels of 0.4-1.4, 0.2-1.0, and 0.97-4.63 pg/g Hb, respectively, are estimated from ETS exposure. These 4-ABP-Hb adduct levels from ETS exposure account for approximately 1-4% of the median levels reported for nonsmokers, explaining, in part, contradictory literature data on 4-ABP-Hb adduct levels in nonsmokers. No risk assessment of ETS or 4-ABP was conducted in this work, consequently the known health effects of ETS are neither confirmed or challenged and our conclusions are limited to the determination that ETS is not a major source of 4-ABP-Hb adduct levels in non-smokers.