Environmental tobacco smoke is a major contributor to lead, cadmium, and arsenic in settled house dust.

Tobacco smoke contains toxic chemicals, including heavy metals lead (Pb), cadmium (Cd), and arsenic (As), that are found in secondhand and thirdhand smoke, the chemical residue that lingers and accumulates in indoor environments. This study examined tobacco smoke's contribution to heavy metal accumulation in house dust after smoking stops. Dust samples were collected from 179 homes of cigarette smokers with young children and analyzed for nicotine and tobacco-specific nitrosamines (TSNAs) using isotope-dilution liquid chromatography-tandem mass spectrometry. Pb, Cd, and As were analyzed by inductively coupled plasma-mass spectrometry. Bivariate correlation and multivariable models were used to examine associations between tobacco use markers and heavy metal dust loading, controlling for sociodemographic, home, and smoking characteristics. All samples contained Pb (geometric mean: 34.2 μg/m2), Cd (0.40 μg/m2), As (1.6 μg/m2), nicotine (15.7 μg/m2), and TSNAs (6.0 ng/m2); 100 % exceeded the current EPA standard for Pb (0 μg/ft2). Metals correlated positively with nicotine (Pb: r = 0.68; Cd: r = 0.70; As: r = 0.70; all p < 0.001) and TSNAs (Pb: r = 0.50; Cd: r = 0.47; As: r = 0.51; all p < 0.001). Nicotine loading was strongly associated with higher loading of the other contaminants (Pb: βˆ = 0.68; Cd: βˆ = 0.71; As: βˆ = 0.69; TSNAs: βˆ = 0.83; all p < 0.001). The semi-partial R2 values showed that nicotine uniquely explained 43 % of Pb, 58 % of Cd, and 54 % of As dust-loading variance. Our model projected that, in a fully tobacco-free home, dust loadings of Pb, Cd, and As would decrease by 87 %, 49 %, and 38 %, respectively. This study provides compelling evidence that tobacco smoke residue is a significant yet underrecognized source of toxic metals in household dust, independent of established factors such as housing age. It substantially contributes to indoor lead, cadmium, and arsenic levels. Given children's heightened vulnerability, these findings highlight the urgency of smoke-free policies and thirdhand smoke remediation.