Researchers are using studies such as this review of data from 24 studies (which examined the blood and urine samples of e-cigarette users to show that e-cigarettes are a source of exposure to a long list of metals, including lead and arsenic) to estimate metal exposure of e-cigarette users.

The project included 29 participating countries (with 27 reporting in time and in the format provided for the project) from the EU and the European Economic Area (EEA) and examined 17 substances, 1,009 mixtures, and 4,599 articles.