Relationships between the nicotine metabolite ratio and a panel of exposure and effect biomarkers: findings from two studies of U.S. commercial cigarette smokers

Abstract

Background:

We examined the nicotine metabolite ratio’s (NMR) relationship with smoking intensity, nicotine dependence, and a broad array of biomarkers of exposure and biological effect in commercial cigarette smokers.

Methods:

Secondary analysis was conducted on two cross-sectional samples of adult, daily smokers from Wave 1 (2013-2014) of the Population Assessment of Tobacco Use and Health (PATH) Study and baseline data from a 2014-2017 randomized clinical trial. Data was restricted to participants of non-Hispanic, White race. The lowest quartile of NMR (< 0.26) in the nationally representative PATH Study was used to distinguish slow from normal/fast nicotine metabolizers. NMR was modeled continuously in secondary analysis.

Results:

Compared to slow metabolizers, normal/fast metabolizers had greater cigarettes per day and higher levels of total nicotine equivalents, tobacco specific nitrosamines, volatile organic componds, and polycyclic aromatic hydrocarbons. A novel finding was higher levels of inflammatory biomarkers among normal/fast metabolizers versus slow metabolizers. With NMR modeled as a continuous measure, the associations between NMR and biomarkers of inflammation were not significant.

Conclusions:

The results are suggestive that normal/fast nicotine metabolizers may be at increased risk for tobacco-related disease due to being heavier smokers, having higher exposure to numerous toxicants and carcinogens, and having higher levels of inflammation when compared with slow metabolizers.

Impact:

This is the first documentation that NMR is not only associated with smoking exposure but also biomarkers of biological effects that are integral in the development of tobacco-related disease. Results provide support for NMR as a biomarker for understanding a smoker’s exposure and potential risk for tobacco-related disease.