Table 1.

Cotinine levels by e-cigarette use characteristics

	Salivary cotinine (ng/ml)
	n(%)	M (SD)	Median	Range
Full sample	173 (100.0%)
Current nicotine use
All e-cigarettes contain nicotine	72 (41.6%)	61.9 (87.3)	17.4	0 – 369.3
Some contain nicotine	67 (38.7%)	31.3 (111.7)	0.0	0 – 864.6
None contain nicotine	13 (7.5%)	2.3 (7.7)	0.0	0 – 27.9
Unknown nicotine content	21 (12.1%)	2.5 (9.6)	0.0	0 – 44.1
Type of e-cigarette used
Customizable / Mod	56 (32.4%)	59.5 (133.5)	6.5	0 – 864.6
Juul	38 (22.0%)	54.3 (90.1)	6.1	0 – 302.8
Vape pen	59 (34.1%)	18.2 (38.9)	0.0	0 – 161.5
Other or unknown	20 (11.6%)	8.5 (23.2)	0.0	0 – 98.8
Daily/Non-Daily e-cigarette use
Daily	25 (14.5%)	114.6 (103.1)	88.8	0 – 369.3
Non-Daily	148 (85.5%)	25.5 (83.7)	.55	0 – 864.6
E-Cigarette only users	144 (83.2%)
Current nicotine use
All e-cigarettes contain nicotine	51 (35.4%)	47.4 (82.3)	9.1	0 – 369.3
Some contain nicotine	60 (41.7%)	24.9 (114.1)	0.0	0 – 864.6
None contain nicotine	12 (8.3%)	0.1 (0.5)	0.0	0 – 1.7
Unknown nicotine content	21 (14.6%)	2.5 (9.6)	0.0	0 – 44.1
Type of e-cigarette used
Customizable / Mod	48 (33.3%)	51.5 (137.3)	3.7	0 – 864.6
Juul	31 (21.5%)	36.1 (75.1)	1.5	0 – 283.0
Vape pen	49 (34.0%)	7.6 (26.7)	0.0	0 – 161.5
Other or unknown	16 (11.1%)	0.3 (0.9)	0.0	0 – 3.3
Daily/Non-Daily e-cigarette use
Daily	15 (10.4%)	93.0 (100.4)	57.8	0 – 369.3
Non-Daily	129 (89.6%)	19.9 (85.6)	0.0	0 –864.6