Figure 5.

Measurements of nicotine and its metabolites in vapers’ sputum. Vapers were asked to vape normally over 1 hour, and sputum was induced immediately afterwards. Metabolite levels were then measured by gas chromatography–mass spectrometry. (A–C) Graphs show concentrations of nicotine (A), cotinine (B), and hydroxycotinine (C), from control subjects (n = 6) and vapers (n = 8). Nicotine concentrations are shown as both micromolar (left) and milligrams per milliliter (right). Data are shown as mean with range along with individual data points and P values. Data were analyzed using the Mann-Whitney U test. OH-Cotinine = hydroxycotinine.