Immediate Switching to Reduced Nicotine Cigarettes in a U.S.-Based Sample: The Impact on Cannabis Use and Related...

The FDA proposed rule-making to reduce nicotine in cigarettes to minimally addictive levels. Research suggests decreasing nicotine levels (i.e. very low nicotine content cigarettes [VLNCs]) produced greater quit attempts, reduced smoking, and reduced exposure to harmful constituents among smokers. The impact of long-term VLNC use among people who co-use cigarettes and cannabis on non-tobacco-specific toxicant and carcinogen exposure has not been investigated.

This study presents secondary analyses of a controlled clinical trial examining switching to VLNC (versus a normal nicotine cigarettes control group [NNCs]) between people who co-use cigarettes and cannabis (n = 174) versus smoked cigarettes (n = 555). Linear mixed-effects models compared changes in smoking behavior, and tobacco-specific (i.e. total nicotine equivalents [TNE], 4-[methylnitrosamino]-1-[3-pyridyl]-1-butanone [NNK; total NNAL]) and non-tobacco-specific (i.e. carbon monoxide (CO), 2-cyanoethylmercapturic acid [CEMA], phenanthrene tetraol [PheT]) toxicant and carcinogen exposure at week 20 (with random intercept for participants). Cannabis use was measured among co-use groups.

CO was significantly lower only among the cigarette-only group assigned VLNCs (interaction: p = .015). Although both VLNC groups demonstrated decreased CEMA, greater decreases emerged among the cigarette-only group (interaction: p = .016). No significant interactions emerged for TNE, cigarettes per day (CPD), NNAL, and PheT (ps > .05); both VLNC groups decreased in TNE, CPD, and NNAL. Only the cigarette-only group assigned VLNCs demonstrated decreased PheT (p < .001). The VLNC co-use group showed increased cannabis use over time (p = .012; 0.5 more days per week by week 20).

Those who co-use cannabis and cigarettes may still be at risk for greater exposure to non-tobacco-specific toxicants and carcinogens compared to those who only smoke cigarettes.

The present study is the longest longitudinal, prospective comparison study of smoking behavior and exposure to harmful constituents among those who co-use cigarettes and cannabis versus cigarette-only after immediately switching to very low nicotine content cigarettes (VLNC). Those who co-use experienced similar reductions in CPD and tobacco-specific exposure, compared to those who only use cigarettes. However, co-use groups experienced smaller reductions in non-tobacco-specific toxicants and carcinogens compared to the cigarette-only group, potentially because of combustible cannabis use. Additionally, those who co-use and switched to VLNC may be susceptible to slight increases in cannabis use (approximately two more days per year).