Metal Exposure from E-Cigarette Users in Maryland

BackgroundAs more is known about the components of electronic cigarettes (e-cigarettes), it is important to characterize metal exposure from use. Nickel (Ni) and chromium (Cr) are frequent components of e-cigarette heating coils and have been found in e-liquid and aerosol. We compared Ni and Cr biomarker concentrations among Maryland e-cigarette users to that of non-e-cigarette users/non-smokers, and also assessed the association of e-cigarette use patterns with metal biomarker concentrations.MethodsWe recruited 50 e-cigarette users and 50 non-e-cigarette users from March to October 2017. Data were collected on health status, e-cigarette use patterns, device characteristics, sociodemographic factors. Urine, saliva, and exhaled breath condensate (EBC) samples were collected. Metal concentrations were measured using ICP-MS.ResultsThe median Cr concentrations for non-users and e-cigarette users were 0.92 and 1.77 μg/l in urine, 0.62 and 0.73 μg/l in saliva, and both 0.14 μg/l in EBC, respectively; median Ni concentrations were 0.68 and 1.11 μg/l in urine, 0.27 and 0.55 μg/l in saliva, and both 0.13 μg/l in EBC. Compared to non-users, e-cigarette users had significantly higher levels of Ni concentration in urine (GMR 3.99, 95% CI: 1.95-8.19, p < 0.001). Increased urine Ni concentrations were observed among users who vaped at a higher voltage (3.65-4.20 volts) and used a higher nicotine concentration (12-24 mg/ml). Saliva Cr concentrations were increased with more e-liquid consumed per week (35 to 60 ml). Both Ni and Cr saliva concentrations were increased among users that changed their coils more frequently (>2/month).ConclusionE-cigarette users had significantly higher levels of Cr in urine than non-users. Ni in urine and Cr in saliva were positively associated with higher e-cigarette use and voltage. Increased metal concentrations in saliva associated with more frequent coil change provide an indication that instructions and best practice of using coils is warranted.