Arsenic species in electronic cigarettes: Determination and potential health risk.

Human exposure to contaminants from electronic cigarettes (e-cigarettes) and the associated health effects are poorly understood. There has been no report on the speciation of arsenic in e-liquid (solution used for e-cigarettes) and aerosols. We report here determination of arsenic species in e-liquids and aerosols generated from vaping the e-liquid. Seventeen e-liquid samples of major brands, purchased from local and online stores in Canada and China, were analyzed for arsenic species using high-performance liquid chromatography and inductively coupled plasma mass spectrometry. Aerosols condensed from vaping the e-liquids were also analyzed and compared for arsenic species. Six arsenic species were detected, including inorganic arsenate (iAsV), arsenite (iAsIII), monomethylarsonic acid (MMA), and three new arsenic species not reported previously. In e-liquids, iAsIII was detected in 59%, iAsV in 94%, and MMA in 47% of the samples. In the condensate of aerosols from vaping the e-liquids, iAsIII was detected in 100%, iAsV in 88%, and MMA in 13% of the samples. Inorganic arsenic species were predominant in e-liquids and aerosols of e-cigarettes. The concentration of iAsIII in the condensate of aerosols (median 3.27 μg/kg) was significantly higher than that in the e-liquid (median 1.08 μg/kg) samples. The concentration of inorganic arsenic in the vaping air was approximately 3.4 μg/m3, which approaches to the permissible exposure limit (10 μg/m3) set by the United States Occupational Safety and Health Administration (OSHA). According to the Environmental Protection Agency's unit risk factor (4.3 × 10-3 per μg/m3) for inhalation exposure to inorganic arsenic in the air, the estimated excess lung cancer risk from lifetime exposure to inorganic arsenic in the e-cigarette vaping air (3.4 μg/m3), assuming e-cigarette vaping at 1% of the time, is as high as 1.5 × 10-4. These results raise health concerns over the exposure to arsenic from electronic cigarettes.