BackgroundElectronic cigarettes (e-cig) vaping, containing nicotine and/or Δ8, Δ9 or Δ10 or Δo tetrahydrocannabinol (Δn−THC) are associated with an outbreak of e-cig, or vaping product use, associated lung injury (EVALI). Despite thousands hospitalised with EVALI, much remains unknown about diagnosis, treatment and disease pathogenesis. Biomarkers of inflammation, oxidative stress, and lipid mediators may help identify e-cig users with EVALI.MethodsWe collected plasma and urine along with demographic and vaping-related data of EVALI subjects (ages: 18–35 years) and non-users matched for sex and age in a pilot study. Biomarkers were assessed by ELISA/EIA and Luminex-based assays.ResultsElevated levels of THC metabolite (11-nor-9-carboxy-THC) were found in plasma from EVALI subjects compared to non-users. Levels of 8-hydroxy-2′-deoxyguanosine (8-OHdG), an oxidative DNA damage biomarker, and 8-isoprostane, an oxidative stress marker, were slightly increased in urine samples from EVALI subjects compared to non-users. Conversely, plasma levels of lipid mediators, including Resolvin D1 (RvD1) and Prostaglandin E2 (PGE2), were significantly lower in EVALI subjects compared to non-users. Both pro-inflammatory biomarkers, such as TNF-α, MIP-1β, RANTES, and GM-CSF, as well as anti-inflammatory biomarkers, such as IL-9 and CC10/16, were decreased in plasma from EVALI subjects compared to non-users, supportive of a possible dysregulated inflammatory response in EVALI subjects.ConclusionsSignificant elevations in urine and plasma biomarkers of oxidative stress, as well as reductions in lipid mediators, were shown in EVALI subjects. These non-invasive biomarkers of 8-OHdG, 8-isoprostane, RvD1, and CC10/16, either individually or collectively, may serve as biomarkers in diagnosing future EVALI subjects.