Table-1.

Toxic components present in e-Cigarette aerosol and e-liquid

Components	Concentration	e-liquid/Aerosol	References
Carbonyl compounds
Formaldehyde	2.0–6.3 µg	150 puff	(Goniewicz et al., 2014)
	1.9–120 µg	10 puff	(Uchiyama et al., 2016)
	0.05–51 µg	1 puff	(Gillman et al., 2016)
	0.1– 9.0 ug	1 g of e-liq	(Varlet et al., 2015)
Acetaldehyde	1.1–13.6 µg	150 puff	(Goniewicz et al., 2014)
	1.4 −73 µg	10 puff	(Uchiyama et al., 2016)
	0.03–40.07 µg	1 puff	(Gillman et al., 2016)
	0.05–10..2 µg	1 g of e-liq	(Varlet et al., 2015)
Acrolein	0.7– 41.9 µg	150 puff	(Goniewicz et al., 2014)
	2.1–16 µg	10 puff	(Uchiyama et al., 2016)
	<0.02–5.5 µg	1 puff	(Gillman et al., 2016)
Propionaldehyde	110 ng	1 puff	(Tayyarah and Long, 2014)
	40–1500 ng	1 puff	(Bekki et al., 2014)
Volatile Organic Compounds
Toluene p,m-xylene	0.2–6.3 µg 0.1–0.2 µg	150 puff 150 puff	(Goniewicz et al., 2014)
Tobacco-Specific Nitrosamines
N-nitrosonornicotine (NNN)	0.8–4.3 ng	150 puff
	0.5–16.7 ng	1 ml of e-liq	(Goniewicz et al., 2014)
4-(methylnitrosamino)-1-(3- pyridyl)-1-butanone (NNK)	1.1– 28.3 ng	150 puff	(Farsalinos et al., 2015)
	3.2 −10.8 ng	1 ml of e-liq
Metals
Ni	0.11–0.29 µg	150 puff
Cd	0.01–0.22 µg	150 puff	(Goniewicz et al., 2014)
Pb	0.03–0.57 µg	150 puff

Reference List

Bekki K, Uchiyama S, Ohta K, Inaba Y, Nakagome H, Kunugita N (Carbonyl compounds generated from electronic cigarettes. Int J Environ Res Public Health 11:11192–11200.2014).

Farsalinos KE, Gillman IG, Melvin MS, Paolantonio AR, Gardow WJ, Humphries KE, Brown SE, Poulas K, Voudris V (Nicotine levels and presence of selected tobacco-derived toxins in tobacco flavoured electronic cigarette refill liquids. Int J Environ Res Public Health 12:3439–3452.2015).

Gillman IG, Kistler KA, Stewart EW, Paolantonio AR (Effect of variable power levels on the yield of total aerosol mass and formation of aldehydes in e-cigarette aerosols. Regul Toxicol Pharmacol 75:58–65.2016).

Goniewicz ML, Knysak J, Gawron M, Kosmider L, Sobczak A, Kurek J, Prokopowicz A, Jablonska-Czapla M, Rosik-Dulewska C, Havel C, Jacob P, III, Benowitz N (Levels of selected carcinogens and toxicants in vapour from electronic cigarettes. Tob Control 23:133–139.2014).

Tayyarah R, Long GA (Comparison of select analytes in aerosol from e-cigarettes with smoke from conventional cigarettes and with ambient air. Regul Toxicol Pharmacol 70:704–710.2014).

Uchiyama S, Senoo Y, Hayashida H, Inaba Y, Nakagome H, Kunugita N (Determination of Chemical Compounds Generated from Second-generation E-cigarettes Using a Sorbent Cartridge Followed by a Two-step Elution Method. Anal Sci 32:549–555.2016).

Varlet V, Farsalinos K, Augsburger M, Thomas A, Etter JF (Toxicity assessment of refill liquids for electronic cigarettes. Int J Environ Res Public Health 12:4796–4815.2015).