The Science of Safety: Debunking the Myths Surrounding Propylene Glycol and Polyethylene Glycol in Vaping Applications

Description During the 2019-2020 vaping health crisis, significant misinformation was published regarding the safety of propylene glycol (PG) and polyethylene glycol (PEG) as thinning agents in cannabis and nicotine vaporizers. This paper examines the primary study driving those claims - a 2017 paper in the Journal of Alternative and Complementary Medicine - and identifies a fundamental methodological flaw: the use of unrealistic testing temperatures (230 degrees C) that do not reflect actual human vaping behavior. The CDC's definitive investigation of the EVALI outbreak identified Vitamin E acetate - not PG or PEG - as the primary culprit, explicitly clearing standard vaping ingredients of involvement. This paper applies consistent temperature-context analysis to both PG and PEG, reviews the decades-long pharmaceutical inhalation safety record for PG, and evaluates the available inhalation toxicology data for PEG at realistic operating temperatures. The conclusion: the legislative and commercial responses that removed PEG from cannabis vaping products were enacted during maximum public fear, based on a conflation of EVALI causes that the CDC's own findings do not support. Document ID: WP-2026-02 | Version 2.0 | Terps USA Research Full research hub: https://terpsusa.com/pages/research Full paper: https://terpsusa.com/pages/pg-peg-vaping-safety-whitepaper