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. Author manuscript; available in PMC: 2022 Jul 11.
Published in final edited form as: Tob Regul Sci. 2020 Jul;6(4):235–241. doi: 10.18001/trs.6.4.2

Figure 1. Mean (+SEM) Urine PG and VG Concentrations for Daily ECIG Users and Controls.

Figure 1.

Mean (+SEM) values for urine propylene glycol (PG) and vegetable glycerin concentration for experienced ECIG users pre- and post- 12-hours ECIG/nicotine abstinence and for controls. Among ECIG users, pound symbols (#) indicate significant differences pre- and post-ECIG/nicotine abstinence. Alpha symbols (α) indicate significant differences between non-abstinent ECIG users and controls; crosses (+) indicate significant differences between 12-hour abstinent ECIG users and controls. Note that, for controls, data for urine VG are presented with two outliers included whose urine VG concentrations were 5–6 times greater than the mean, possibly due to greater than average exposures to VG-containing food and/or products.