Magnitudes of biomarker reductions in response to controlled reductions in cigarettes smoked per day: A one-week clinical confinement study

• Published in: Regulatory toxicology and pharmacology 2015-03, Vol.71 (2), p.225-234
• Main Authors: Theophilus, Eugenia H., Coggins, Christopher R.E., Chen, Peter, Schmidt, Eckhardt, Borgerding, Michael F.
• Format: Article
• Language: English
• Subjects: Adult; Aged; Biomarkers; Biomarkers - metabolism; Cessation; Cigarettes; Clinical confinement; Dose-Response Relationship, Drug; Female; Humans; Male; Middle Aged; Smoking - epidemiology; Smoking - metabolism; Smoking - trends; Smoking Cessation - methods; Surveys and Questionnaires; Time Factors; Tobacco Products; Young Adult
• ISSN: 0273-2300; 1096-0295
• DOI: 10.1016/j.yrtph.2014.12.023

•We assessed effects of reduced cigarette consumption on biomarkers of exposure.•We used 120 smokers confined in a clinic over a one-week period.•Smokers were switched from 20 cigarettes per day (CPD) to 0, 5, 10 or 20 CPD.•Switching led to biomarker reductions broadly proportional to CPD reduction.•None of the biomarkers were reduced to zero. Tobacco toxicant-related exposure reduction is an important tool in harm reduction. Cigarette per day reduction (CPDR) occurs as smokers migrate from smoking cigarettes to using alternative tobacco/nicotine products, or quit smoking. Few reports characterize the dose–response relationships between CPDR and effects on exposure biomarkers, especially at the low end of CPD exposure (e.g., 5 CPD). We present data on CPDR by characterizing magnitudes of biomarker reductions. We present data from a well-controlled, one-week clinical confinement study in healthy smokers who were switched from smoking 19–25 CPD to smoking 20, 10, 5 or 0 CPD. Biomarkers were measured in blood, plasma, urine, and breath, and included smoke-related toxicants, urine mutagenicity, smoked cigarette filter analyses (mouth level exposure), and vital signs. Many of the biomarkers (e.g., plasma nicotine) showed strong CPDR dose–response reductions, while others (e.g., plasma thiocyanate) showed weaker dose–response reductions. Factors that lead to lower biomarker reductions include non-CPD related contributors to the measured response (e.g., other exposure sources from environment, life style, occupation; inter-individual variability). This study confirms CPDR dose-responsive biomarkers and suggests that a one-week design is appropriate for characterizing exposure reductions when smokers switch from cigarettes to new tobacco products.