Table 2.

Selected WPT flavorants, related compounds, odor, and applicable toxicity studies.

Compound class	WPT flavorants and related compounds	Characteristic odor	Relevant WPT flavors	Toxicity studies
Esters	2-Hexenol acetate	Fruity	Melon, apple, unflavored	Acute inhalation toxicity at dosage of 500 ppm (Silverman 1946).
	Ethyl cinnamate	Spices/cinnamon	Guava	Cytotoxicity in lung fibroblast and epithelium (Behar et al. 2018).
	n-Hexyl acetate	Fruity	Melon	Acute inhalation toxicity at dosage of 500 ppm (Silverman 1946).
	Triacetin	Odorless	Green grape	Cytotoxicity in lung fibroblast and epithelium (Behar et al. 2018).
Ketones	2,3-Butanedione (diacetyl)	Buttery	Melon, unflavored	Peribronchial inflammation, mild nasal and laryngeal injury after exposure of diacetyl 100–400 ppm for at least 4 wks (Morgan et al. 2008).
Terpenes and Terpenoids	Limonene	Citrus/fruity	Watermelon	Cytotoxicity and induced inflammatory responses in naïve monocyte (Morris et al. 2021).
Aldehydes and Furans	Ethyl vanillin	Vanilla/dessert	Green grape	Induced cytotoxicity in lung epithelium and associated with lung obstructive or restrictive diseases (Hua et al. 2019).
	p-Anisaldehyde	Spices	Licorice	Cytotoxicity in lung fibroblast and epithelium (Behar et al. 2018).
	Furfural	Sweet	Caramel, almond	Irritated when inhaled and induced injury in parenchymal area (Gupta et al. 1991).
	Furaneol	Fruity	Strawberry	Cytotoxicity to lung epithelium (Hua et al. 2019).
Aromatic compounds	Phenol	Sweet	Apple, green grape, guava, melon	Phenol exposure at 1.7 mg/ml showed cytotoxicity and mitochondrial activity inhibition in ex vivo human lung slice (Galina et al. 2018).
Alcohols	2-Ethyl-1-hexanol	Odorless	Melon	Acute exposure to 1 mg/m3 caused irritation to nasal, throat, and respiratory track (Ernstgard et al. 2010).
	Eugenol	Spice/clove	Green grape	Cytotoxicity in lung fibroblast and epithelium (Behar et al. 2018).