Fig. 1

Biomarkers of exposure among subgroups of people who smoke and vape relative to people who only smoke cigarettes everyday, Population Assessment of Tobacco and Health Study Wave 1, 2013–2014. TNE-7, total nicotine equivalents-7 (cotinine, trans-3’-hydroxycotinine, cotinine N-oxide, nicotine N-oxide, norcotinine, nornicotine, and nicotine); NNAL, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol; NNN, N'-Nitrosonornicotine; 2-FLU, 2-hydroxyfluorene; 3-FLU, 3-hydroxyfluorene; 1-PYR, 1-hydroxypyrene; AAMA, N-Acetyl-S-(2-carbamoylethyl)-l-cysteine; CEMA, N-Acetyl-S-(2-carboxyethyl)-l-cysteine; CYMA, N-Acetyl-S-(2-cyanoethyl)-l-cysteine; 2HPMA, N-Acetyl-S-(2-hydroxypropyl)-l-cysteine; 3HPMA, N-Acetyl-S-(3-hydroxypropyl)-l-cysteine; HPMM, N-Acetyl-S-(3-hydroxypropyl-1-methyl)-l-cysteine; IPM3, N-Acetyl-S-(4-hydroxy-2-methyl-2-buten-1-yl)-l-cysteine; MADA, Mandelic acid; MHB3, N-Acetyl-S-(4-hydroxy-2-buten-1-yl)-l-cysteine; PHGA, Phenylglyoxylic acid. Note *Denotes statistically significant difference at unadjusted p < 0.05 between subgroups of people who smoke and vape and people who only smoke cigarettes everyday. Group A—people who only smoke cigarettes everyday; Group B1—people who frequently smoke and vape; Group B2—people who frequently smoke and infrequently vape; Group B3—people who frequently vape and infrequently smoke; Group B4—people who infrequently smoke and vape; Group C—people who only vape everyday; Group D—people who never used any tobacco products