Characteristics of Organophosphate Ester Formation during Smoking

This study examines the occurrence of organophosphate esters (OPEs) in cigarettes and sidestream cigarette smoke and to see the OPE formation characteristics during smoking. All seven OPEs in both gas and particulate phases were measured in sidestream cigarette smoke for four brands of cigarettes. Tributyl phosphate (TBP), tris(2-butoxyethyl) phosphate (TBEP), tris(2-chloroethyl) phosphate (TCEP), and triphenyl phosphate (TPP) were found frequently. Median total OPE increases in the air samples during smoking were 56.2 ng per cigarette for gas-phase OPEs and 2360 ng per cigarette for particulate-phase OPEs. TBP and TCEP could be absorbed to particles in air more readily than alkans as seen from the correlation line between gas–particle partition coefficients (Kp) and the subcooled liquid vapor pressures (PLº) for alkans. Furthermore, TBP was determined in the cigarettes. Median total OPE decreases in the cigarette samples during smoking were 1200 ng per cigarette. The combustion reaction increased TBP and TBEP levels in cigarettes, and particulate-phase TBEP in air appeared to influence the production of TBP, TCEP, and TPP. TBP and TBEP in cigarettes likely affect the production of TBP, TBEP, TCEP, and TPP in air during smoking.