Table 1.

Chemical compounds exclusively reported in electronic cigarettes liquids.

Name	Cas registry number	Health effect	Classification	Reference
(+)-aromadendrene	489-39-4	Cytotoxic/skin irritation	i.e	[24]
				[25]
(Z)-3-Hexen-1-ol	928-96-1	Eye irritation	i.e	[24]
1-Methyl phenanthrene	832-69-9	Cytotoxic/Eye irritation/Skin irritation	Group 3	[24]
				[26]
1,3-Butanediol	107-88-0	Low concern based on experimental and modeled data	i.e	[27]
1,3-Propanediol	504-63-2	Not a significant hazard via inhalation of either the gas phase or a gas/aerosol mixture	i.e	[27]
				[28]
2-Acetylpyrrole	1072-83-9	Skin irritation	i.e	[24]
2,3-Dimethylpyrazine	5910-89-4	Cytotoxic	i.e	[24]
2,3-Pentanedione	600-14-6	Skin irritation/ eye irritation/ systemic organ irritation	i.e	[24]
2,3,5-Trimethylpyrazine	14667-55-1	Cytotoxic	i.e	[24]
3-Methyl-1-butanol	123-51-3	Cytotoxic/ skin irritation/ eye irritation/ respiratory tract irritation	i.e	[24]
				[29]
Acetic acid	64-19-7	Respiratory tract irritation	i.e	[26]
Benzyl acetate	140-11-4	Cytotoxic/ eye irritation/ respiratory tract irritation	Group 3	[29]
Benzyl alcohol	100-51-6	Cytotoxic	i.e	[24]
Butyl butyrate	109-21-7	Eye irritation/mild effects/ behavioral Effects	i.e	[29]
Camphor	76-22-2	Cytotoxic/ neurotoxic/ systemic organ irritation/ mild effects/ behavioral effects	i.e	[24]
Cinnamaldehyde	104-55-2	Eye irritation/ respiratory tract irritation/ systemic organ irritation	i.e	[29]
Cinnamyl alcohol	104-54-1	Unknown effects in human health	i.e	[24]
Coumarin	91-64-5	Behavioral effects/ systemic organ irritation	Group 3	[29]
Methyl cyclopentenolone	80-71-7	Unknown effects in human health	i.e	[24]
Diacetyl	431-03-8	Eye irritation/ skin irritation	i.e	[29]
Diethylene glycol	111-46-6	Systemic organ irritation/ skin irritation	i.e	[29]
Ethyl butyrate	105-54-4	Mild effects/ behavioral effects	i.e	[29]
				[27]
Ethyl maltol	4940-11-8	Cytotoxic	Unknown	[29]
Ethyl vanillin	121-32-4	Unknown effects in human health	Unknown	[29]
Ethylene glycol	107-21-1	Harmful effects in animal models	Unknown	[30, 31]
Glycerin	56-81-5	Eye irritation/ skin irritation/ respiratory tract irritation	Unknown	[1, 32]
Hydroxyacetone	116-09-6	Cytotoxic	i.e	[33]
i-Butyric acid	79-31-2	Respiratory tract irritation	i.e	[29]
Isobutyl acetate	110-19-0	Eye irritation/ skin irritation / respiratory tract irritation/ mild effects	i.e	[29]
Isoamyl acetate	123-92-2	Eye irritation/ skin irritation / respiratory tract irritation	Unknown	[26]
Isopentyl isovalerate	659-70-1	Harmful effects in animal models	i.e	[25]
L-Menthyl acetate	89-48-5	Respiratory tract irritation	i.e	[26]
Limonene	138-86-3	No evidence of carcinogenic activity in rats or human	i.e	[34]
Maltol	118-71-8	Cytotoxic	Unknown	[26]
Menthone	89-80-5	Harmful effects in animal models	i.e	[29]
Methyl anthranilate	134-20-3	Unknown effects in human health	i.e	[29]
				[25]
Methyl cinnamate	103-26-4	Unknown effects in human health	i.e	[35]
Methyl salicylate	119-36-8	Neurotoxin / cardiovascular effects	Unknown	[25]
Myosmine	532-12-7	Carcinogenic	Unknown	[36]
n-Hexanol	111-27-3	Harmful effects in animal models	i.e	[29]
Nicotyrine	487-19-4	Unknown effects in human health	i.e	[37]
o-Tolualdehyde	529-20-4	Harmful effects in animal models/ unknown effects in human health	Unknown	[26]
				[37]
p-Cymene	99-87-6	Skin irritation/ mild effects	i.e	[26]
Propylene Glycol	57-55-6	Respiratory tract irritation	Unknown	[38]
Safrole	94-59-7	Harmful effects in animal models	Group 2B	[26]
Thujone (sum of α- and β-diastereomers)	76231-76-0	Harmful effects in animal models	i.e	[39]
Trans-2-hexen-1-ol	928-95-0	Unknown effects in human health	i.e	Sigma-aldrich safety data sheet
Vanillin	121-33-5	Cytotoxic	Unknown	[40]
β–Damascone	23726-93-4	Skin irritation	Unknown	[41]
γ–Decalactone	706-14-9	Respiratory tract irritation	i.e	[29]