“…Many metals and metalloids are essential for biological function, but chronic and acute exposure of humans to certain elements, such as nickel, chromium, lead, and arsenic, are known to have adverse toxicity when intake exceeds recommended amounts [ 13 , 14 , 15 ]. Humans are typically exposed to metals through a variety of pathways, including ingestion or inhalation of contaminated soil, dust, bioaccumulation in food, water, pesticides, and other sources [ 16 , 17 , 18 , 19 , 20 , 21 , 22 ]. Recent studies have shown that some of the metals found in electronic cigarettes accumulate in the central nervous system of mice after exposure, appear in various biomarkers of e-cigarette users, and have been shown to cause cellular damage [ 1 , 8 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ].…”