THC from vaping deposits on room surfaces, creating potential third-hand exposure
THC was detected on surfaces in a room where cannabis was vaporized, at levels ranging from 348 to 4,882 ng/m2, demonstrating that cannabis vapor leaves measurable residue on surfaces.
Quick Facts
What This Study Found
THC was detected on 6 of 15 surface samples collected from a room where cannabis was vaporized, at quantifiable levels of 348-4,882 ng/m2. All control samples from outside the study room were negative.
Key Numbers
6 of 15 surface samples positive for THC. Levels: 348-4,882 ng/m2. All negative controls were clean.
How They Did This
Surface samples were collected using isopropanol-imbued non-woven wipes from hard surfaces and objects in a room where cannabis was vaporized. Samples were analyzed using LC-ESI-MS/MS with online extraction. Standardized three-pattern swabbing protocol was used.
Why This Research Matters
Third-hand tobacco smoke exposure (from surface residue) is a recognized health concern. This is the first study to show that cannabis vapor similarly deposits on surfaces, creating a potential exposure pathway for non-users in shared spaces.
The Bigger Picture
As cannabis vaping increases in homes, workplaces, and rental properties, surface deposition could lead to unintended cannabinoid exposure for children, pets, and non-users who touch contaminated surfaces.
What This Study Doesn't Tell Us
Single room study. Unknown how long THC persists on surfaces. Unknown whether surface-deposited THC is bioavailable through skin contact. Only THC was measured; other cannabinoids were not assessed.
Questions This Raises
- ?Can surface-deposited THC be absorbed through skin contact?
- ?Does it accumulate over time with repeated use?
- ?Would standard cleaning remove it?
- ?Could surface THC cause a positive drug test?
Trust & Context
- Key Stat:
- THC found on surfaces up to 4,882 ng/m2 after vaping
- Evidence Grade:
- Preliminary: proof-of-concept study in a single room with small sample number.
- Study Age:
- Published in 2019.
- Original Title:
- Surface Detection of THC Attributable to Vaporizer Use in the Indoor Environment.
- Published In:
- Scientific reports, 9(1), 18587 (2019)
- Authors:
- Sempio, Cristina(20), Lindley, Emily, Klawitter, Jost(20), Christians, Uwe, Bowler, Russell P, Adgate, John L, Allshouse, William, Awdziejczyk, Lauren, Fischer, Sarah, Bainbridge, Jacquelyn, Vandyke, Mike, Netsanet, Rahwa, Crume, Tessa, Kinney, Gregory L
- Database ID:
- RTHC-02288
Evidence Hierarchy
Watches what happens naturally without intervening.
What do these levels mean? →Frequently Asked Questions
What is third-hand exposure?
Third-hand exposure occurs when residue from smoke or vapor deposits on surfaces and is later encountered by touching those surfaces. This is different from secondhand exposure (inhaling nearby smoke/vapor).
Is this a health risk?
Unknown at this point. The study demonstrated that THC deposits on surfaces, but whether the amounts are sufficient to cause health effects through skin contact or ingestion has not been studied.
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Cite This Study
https://rethinkthc.com/research/RTHC-02288APA
Sempio, Cristina; Lindley, Emily; Klawitter, Jost; Christians, Uwe; Bowler, Russell P; Adgate, John L; Allshouse, William; Awdziejczyk, Lauren; Fischer, Sarah; Bainbridge, Jacquelyn; Vandyke, Mike; Netsanet, Rahwa; Crume, Tessa; Kinney, Gregory L. (2019). Surface Detection of THC Attributable to Vaporizer Use in the Indoor Environment.. Scientific reports, 9(1), 18587. https://doi.org/10.1038/s41598-019-55151-5
MLA
Sempio, Cristina, et al. "Surface Detection of THC Attributable to Vaporizer Use in the Indoor Environment.." Scientific reports, 2019. https://doi.org/10.1038/s41598-019-55151-5
RethinkTHC
RethinkTHC Research Database. "Surface Detection of THC Attributable to Vaporizer Use in th..." RTHC-02288. Retrieved from https://rethinkthc.com/research/sempio-2019-surface-detection-of-thc
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.