An electronic nicotine delivery system (ENDS) or vape decreased exposure to a major lung carcinogen in people who smoke who were interested in reducing the use of cigarettes.
This is the major finding of a large-scale, randomized, controlled trial in which investigators tested whether an ENDS that differed in the concentration of nicotine delivered produced different exposures to tobacco-related toxicants.1
The study, which was funded by the National Institutes of Health and the US Food and Drug Administration, and reported in The Lancet Respiratory Medicine, included 520 adults who smoke who were randomized in a 1:1:1:1 fashion for 24 weeks to 1 of 4 groups. Three ENDS groups were each paired with a specific concentration of liquid nicotine: no nicotine delivery (0 mg/mL), low nicotine delivery (8 mg/mL), or cigarette-like delivery (36 mg/mL). A fourth group received a non-ENDS product that delivered no nicotine or aerosol.
All participants in the study were aged 21 to 65 years, smoked more than 9 cigarettes daily, had an exhaled carbon monoxide level of >9 parts per million at screening, and, at the time of recruitment, had not used any non-cigarette nicotine delivery product during the previous 7 days or any ENDS for 5 days or more during the previous 28 days. All participants wanted to reduce or quit smoking.
The primary outcome of the study was tobacco-related toxicant exposure to the lung carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), as measured by the total urinary metabolite 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) and glucuronides (pg/mg of creatinine) in each group at 4, 12, and 24 weeks.
At 24 weeks, participants in the ENDS group with cigarette-like delivery had lower levels of NNAL than did participants in the non-ENDS group (210.80 pg/mg of creatinine [CI, 163.03-274.42 pg/mg] versus 346.09 pg/mg of creatinine [CI, 265.00-455.32 pg/mg; P = 0.006]). No differences were found among any groups at 4 or 12 weeks.
Although a number of randomized trials have shown an association between smoking reduction or cessation and decreases in exhaled carbon monoxide with ENDSs, few studies have looked at the different concentrations of nicotine delivered through an ENDS.
The study fills in some gaps by examining the effects of a range of ENDS nicotine delivery profiles and comparing them with a non-ENDS product. “This study adds to others regarding the role of ENDSs for harm reduction among cigarette smokers,” says Dr. Cobb. “In the short term it supports limited safety concerns for the use of these specific ENDSs/liquids in combination with cigarette smoking. The long-term effects of ENDS products, however, are still uncertain.”