. Author manuscript; available in PMC: 2024 Aug 11.

Published in final edited form as: Chem Res Toxicol. 2021 Oct 5;34(10):2216–2226. doi: 10.1021/acs.chemrestox.1c00253

Table 4:

Overview of 6 compounds quantified and detection frequencies for e-liquids and aerosols of analyzed products.

Compound	Chemical class	Relevant use(s)	Hazard class^* / health effects
Caffeine	Purine alkaloid	Central nervous system stimulant	Irritant^†
Isophorone	α,β-unsaturated ketone	Solvent, flavorant	Irritant; Health Hazard
Citroflex-A4 (Tributyl O-acetylcitrate)	Citrate	Plasticizer	Induces CYP3A4⁵⁹
Tributylphosphine oxide	Organophosphorous compound	Catalyst, flame retardant	Corrosive; Irritant^†; generally regarded as toxic
Citroflex-2 (Triethyl citrate)	Citrate	Emulsifier	Irritant^†
Vanillin	Phenol, benzaldehyde	Flavorant	Irritant^†

Globally Harmonized System (GHS) hazard classification is given unless otherwise indicated.

^†

Irritant hazard class in GHS refers to dermal irritation