Carcinogen and Toxicant Exposure Among Young Adults Who Co-Use E-cigarettes and Cannabis (Co-Tox Study)

Inclusion Criteria: * Young adult (18-25 years old). * Ability to read and write in English. * Participants must fall into one of the following groups (based on self-report): * Predominant e-cigarette consumer: defined as using nicotine-containing e-cigarettes daily for the past six months but not having used other nicotine containing products more than weekly or cannabis products for the past month. * Predominant cannabis consumer: defined as using cannabis at least 3x/week for the past six months in any form, including smoking, vaping, and oral use, with no more than weekly use of any nicotine or tobacco products. * E-cigarette-cannabis co-consumers: defined as daily use of nicotine e-cigarettes and use of cannabis at least 3x/week, including smoking, vaping, and oral use, for at least the past six months, with no use of other nicotine containing products more than weekly. * No self-reported diagnosis of kidney disease (current, or within the past year prior to the study visit). * Participants must understand the voluntary nature of this study and sign a written informed consent form before proceeding with study activities. Exclusion Criteria: * Individuals under the age of 18 or over the age of 25. * Currently pregnant or breastfeeding (female participants). * Unwilling or unable to follow protocol requirements