Urinary excretion of exposure biomarkers ( nicotine equivalents [ NE ] , total and free 4 - ( methylnitrosamino ) -1 - ( 3-pyridyl ) -1 - butanol [ NNAL ] , 1-hydroxypyrene , and 3-hydroxypropyl mercapturic acid ) as well as carboxyhemoglobin and plasma cotinine were measured at baseline , Day 5 , and Day 10 .