An epigenetic biomarker (cg05575921 methylation) detected tobacco and cannabis smoke exposure in high school students, with dual users showing the greatest cumulative smoke exposure.
Adolescent medicine specialists, substance use researchers, and clinical laboratory scientists developing smoke exposure tests.
Epigenetic biomarker detected smoke exposure but not e-cigarette use
What the researchers found
Increasing proportions of students tested positive for cotinine (5-16%), THC (3-10%), and the epigenetic biomarker (5-7%) from 10th to 12th grade. Self-reported combusted tobacco and cannabis use correlated strongly with all biomarkers. The epigenetic marker did not detect e-cigarette use. Dual tobacco-cannabis users had the greatest cumulative exposure. Willingness to smoke and positive perceptions of smokers predicted biomarker positivity.
Why it matters
Self-reported substance use is unreliable in adolescents. An objective epigenetic biomarker that detects both tobacco and cannabis smoke exposure could improve screening, research accuracy, and clinical care.
The numbers in context
442 (10th grade), 376 (11th), 366 (12th) participants. Cotinine positive: 5-16%. THC positive: 3-10%. cg05575921 positive: 5-7%. Epigenetic marker correlated with combusted but not e-cigarette use. Dual users had greatest methylation changes.
How the study worked
Longitudinal study of Iowa 10th graders with a friend or family member who smoked, followed through 12th grade. Blood samples at each timepoint for serum cotinine, THC, and DNA methylation at cg05575921. Self-report data on nicotine, tobacco, cannabis, and e-cigarette use.
What this study cannot tell us
High-risk sample (all had a smoking friend or family member) limits generalizability. Epigenetic marker cannot distinguish between tobacco and cannabis smoke exposure. Blood-based testing is more invasive than saliva-based alternatives. Relatively small sample for biomarker validation.
How to read the evidence
Longitudinal validation with multiple biological markers, but high-risk sample and inability to distinguish tobacco from cannabis smoke.
When this study was published
2021 longitudinal study. Demonstrates a novel approach to objective substance use detection in adolescents.
The bigger picture
As adolescent substance use patterns shift between combusted tobacco, e-cigarettes, and cannabis, biomarkers that distinguish between routes of administration become increasingly valuable for research and clinical screening.
Questions still open
- Could this biomarker be used in clinical screening programs? Would saliva-based versions be feasible for broader screening? Can the biomarker distinguish between heavy and light cannabis use? Does the epigenetic change reverse with cessation?
Common questions
What is an epigenetic biomarker?
Can this test tell if a teenager is smoking cannabis?
Read the original research
An Examination of Risk Factors for Tobacco and Cannabis Smoke Exposure in Adolescents Using an Epigenetic Biomarker.
Frontiers in psychiatry, 12, 688384
Citation
Andersen, Allan; Gerrard, Meg; Gibbons, Frederick X; Beach, Steven R H; Philibert, Robert. (2021). An Examination of Risk Factors for Tobacco and Cannabis Smoke Exposure in Adolescents Using an Epigenetic Biomarker.. Frontiers in psychiatry, 12, 688384. https://doi.org/10.3389/fpsyt.2021.688384
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