A pilot study on nicotine residues in houses of electronic cigarette users, tobacco smokers, and non-users of nicotine-containing products
Tobacco cigarettes and electronic cigarettes (e-cigarettes) varyin many ways. Tobacco cigarettes emit smoke which is createdby the combustion of tobacco whereas electronic cigarettes emita vapour that is produced when an atomizer heats up e-liquidwhich is a nicotine solution in propylene glycol and/or vegetableglycerin. Tobacco smoke contains numerous toxicants that areformed by combustion such as carbon monoxide and polyaromatichydrocarbons (PAHs). Although some toxicants have been foundin e-cigarette vapours, the levels are significantly lower than intobacco smoke (Goniewicz et al., 2014). Studies have shown that e-cigarette users exhale some vapour which contain nicotine, but atthe significantly lower levels than the amount of nicotine released from tobacco cigarette secondhand smoke (Czogala et al., 2014).Therefore the bystander would be exposed to low nicotine in the air,while exposure to many toxicants would be significantly reducedor eliminated when compared to tobacco smoke.
Thirdhand cigarette smoke (THS) is the residue of secondhandsmoke that can persist in air, dust and on surfaces (Bahl, Jacob,Havel, Schick, & Talbot, 2014; Bell, 2014). This phenomenon hasbeen documented for years in regards to tobacco cigarettes andrecently has been gaining attention (Barnoya & Navas-Acien, 2013;Matt, Quintana, Destaillats, Gundel, & Sleiman, 2011). This is notbecause it is a new concept, but it is due to that fact that it was onlyrecently named and depicted as an expected extension of second-hand smoke (Bell, 2014). It has been shown that THS is a result ofburning tobacco cigarettes; however there is currently no data onwhether using e-cigarettes in indoor spaces (so called ‘vaping’) cancause significant thirdhand exposure to nicotine.
Studies have shown that nicotine emitted with secondhandtobacco smoke can stick to various surfaces (Bahl et al., 2014; Mattet al., 2004; Sleiman et al., 2010). This residual nicotine can thenreact with other airborne oxidizing chemicals to create carcinogens and mutagens. These are usually in the form of tobacco-specificnitrosamines (TSNAs) (Sleiman et al., 2010). Non-smoking resi-dents and smokers are exposed to these chemicals in amounts3–8 times higher when tobacco cigarette smoking occurs indoorscompared to outdoors (Matt et al., 2004). One study found thatcumulative TSNA exposure from THS is 16 times higher in toddlersand 56 times higher in adults than what would be inhaled by anon-smoker (Bahl et al., 2014). It was also reported that cumula-tive nicotine exposure from THS residue can be 6.8 times higher intoddlers and 24 times higher in adults (Matt et al., 2004).
We have previously shown that in controlled laboratory condi-tions vapours released directly from e-cigarette can be deposited onvarious surfaces and contribute to thirdhand exposure (Goniewicz& Lee, 2014). However, the exposure patterns and nicotine deposi-tion in real-life situations (outside laboratory) may be affected byvarious environmental factors. For example, if inhaled nicotine iseffectively absorbed from vapours in e-cigarette users’ lungs, theamount exhaled by users would be very low. The aim of this studywas to verify whether nicotine from e-cigarettes can be depositedon surfaces in houses of e-cigarette users.