A review of constituents identified in e-cigarette liquids and aerosols.
Level 5 - mechanism / opinion, no new human data
Systematic literature review of laboratory chemical analysis studies with no human clinical trial data.
PubMed 33585727 · doi:10.18332/tpc/131111
What was done
A comprehensive search of scientific databases through July 2020 identified 28 English-language studies evaluating qualitative and quantitative chemical constituents in e-cigarette liquids and aerosols. Across the included literature, 18 articles evaluated e-liquids, 15 evaluated aerosols, and 5 evaluated both mediums.
What was found
The reviewed studies identified 60 unique compounds in e-liquids and 47 in aerosols. A total of 22 compounds were detected in both mediums: acenaphthylene, acetaldehyde, acetol, antimony, benzaldehyde, benzene, chromium, copper, diacetyl, formaldehyde, glycerol, lead, limonene, naphthalene, nickel, nicotine, nicotine-N'-oxides, NNK, NNN, propylene glycol, toluene, and vegetable glycerin. Quantitative levels varied substantially due to differing laboratory analytical methods across studies.
Why it matters
This synthesis provides a baseline inventory of known chemical constituents in e-cigarette products—including heavy metals, carcinogens, and flavorings—to inform toxicological risk assessments and product regulation.
Limits
The review relies on laboratory studies with heterogeneous analytical methodologies, limiting the consistency of reported chemical concentrations. It does not measure human exposure doses, clinical health outcomes, or the biological impact of secondhand aerosol exposure.
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