title: Cytotoxicity evaluation of electronic cigarette vapor extract on cultured mammalian fibroblasts (ClearStream-LIFE): comparison with tobacco cigarette smoke extract.
abstract: BACKGROUND
  Electronic cigarettes (ECs) are used as alternatives to smoking; however, data on their cytotoxic potential are scarce.
  
  
  OBJECTIVE
  To evaluate the cytotoxic potential of 21 EC liquids compared to the effects of cigarette smoke (CS).
  
  
  METHODS
  Cytotoxicity was evaluated according to UNI EN ISO 10993-5 standard. By activating an EC device, 200 mg of liquid was evaporated and was extracted in 20 ml of culture medium. CS extract from one cigarette was also produced. The extracts, undiluted (100%) and in five dilutions (50%, 25%, 12.5%, 6.25% and 3.125%), were applied to cultured murine fibroblasts (3T3), and viability was measured after 24-hour incubation by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay. Viability of less than 70% was considered cytotoxic.
  
  
  RESULTS
  CS extract showed cytotoxic effects at extract concentrations above 12.5% (viability: 89.1 ± 3.5% at 3.125%, 77.8 ± 1.8% at 6.25%, 72.8 ± 9.7% at 12.5%, 5.9 ± 0.9% at 25%, 9.4 ± 5.3% at 50% and 5.7 ± 0.7% at 100% extract concentration). Range of fibroblast viability for EC vapor extracts was 88.5-117.8% at 3.125%, 86.4-115.3% at 6.25%, 85.8-111.7% at 12.5%, 78.1-106.2% at 25%, 79.0-103.7% at 50% and 51.0-102.2% at 100% extract concentration. One vapor extract was cytotoxic at 100% extract concentration only (viability: 51.0 ± 2.6%). However, even for that liquid, viability was 795% higher relative to CS extract.
  
  
  CONCLUSIONS
  This study indicates that EC vapor is significantly less cytotoxic compared tobacco CS. These results should be validated by clinical studies.
authors.affiliation: Abich srl, biological and chemical toxicology research laboratory, Verbania (VB), Italy.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Romagna
authors.forename: Elena
authors.initials: E
authors.lastname: Allifranchini
authors.forename: Elena
authors.initials: E
authors.lastname: Bocchietto
authors.forename: Stefano
authors.initials: S
authors.lastname: Todeschi
authors.forename: Mara
authors.initials: M
authors.lastname: Esposito
authors.forename: Konstantinos E
authors.initials: KE
authors.lastname: Farsalinos
mesh_terms: D000818:Animals; D041702:BALB 3T3 Cells; D002470:Cell Survival / Q000187:drug effects; D045424:Complex Mixtures / Q000633:toxicity*; D055615:Electrical Equipment and Supplies; D051379:Mice; D012906:Smoke; D062789:Tobacco Products
chemical_list: D045424:Complex Mixtures; D012906:Smoke