Nornicotine in Smokeless Tobacco as a Precursor for Carcinogen Exposure

Inclusion Criteria: * Male or female adult smokeless tobacco users 18-65 years of age, using at least 3 tins of product per week for 6 months; * Used the same brand for \>80% of their smokeless tobacco use over the course of at least 6 months, and used this brand exclusively for at least two weeks prior to the eligibility screening; * Not smoking or using any other nicotine or tobacco product in the past 2 weeks (expired CO \< 6 ppm); * Participants are in good physical health (no unstable medical condition) and good general oral health as determined by the licensed medical professional; * Participants are in stable, good mental health (e.g. not currently, within the past 6 months, experiencing unstable or untreated psychiatric diagnosis, including substance abuse) as determined by the licensed medical professional; * Participants who are not taking any medications that affect relevant metabolic enzymes; * Women who are not pregnant or nursing or planning to become pregnant; * Participants have provided written informed consent to participate in the study. Exclusion Criteria: * Significant immune system disorders, respiratory diseases, kidney or liver diseases or any other medical disorders that may affect biomarker data as determined by the licensed medical professional; * Vital signs out of range as determined by the licensed medical professional (participants failing for vital signs will be allowed to re-screen once): * Evident poor oral health (significant gum recession, dental caries, tooth loss) as determined by the general oral health status check; * Excessive drinking (e.g., 5 or more drinks daily) or problems with drinking or drugs (e.g., self-report of binge drinking alcohol or treatment for drug or alcohol abuse within last 3 months); to be assessed by PI or licensed medical professional; * Regular smoking or tobacco use (e.g., greater than once a week) other than oral smokeless tobacco products; * Currently (within the past 2 weeks) using nicotine replacement or other tobacco cessation products (to minimize confounding effects of another product);