Just One Minute of Marijuana Secondhand Smoke Impaired Blood Vessel Function for 90 Minutes
A single minute of exposure to marijuana secondhand smoke impaired blood vessel function in rats for at least 90 minutes, substantially longer than comparable impairment from tobacco secondhand smoke, and the effect did not require cannabinoids.
Quick Facts
What This Study Found
Researchers exposed rats to marijuana secondhand smoke at levels comparable to real-world tobacco secondhand smoke conditions and measured blood vessel function using femoral artery flow-mediated dilation (FMD), a standard measure of endothelial health.
Just one minute of marijuana smoke exposure impaired FMD to a comparable extent as tobacco smoke. However, the recovery time was dramatically different: tobacco smoke impairment resolved relatively quickly, while marijuana smoke impairment persisted for at least 90 minutes.
Critically, the impairment occurred even when the marijuana had no cannabinoids (THC, CBD removed) and when the rolling paper was removed (burning marijuana plant only). This means the vascular damage was caused by the combustion products themselves, not by any specific component of cannabis or rolling paper.
Endothelium-independent vasodilation (tested with nitroglycerin) was not affected, confirming the damage was specific to the endothelial cells lining blood vessels.
Key Numbers
1 minute of marijuana SHS impaired FMD comparably to tobacco SHS. Marijuana SHS impairment lasted at least 90 minutes, longer than tobacco. Effect occurred without cannabinoids and without rolling paper. Endothelium-independent dilation was not affected.
How They Did This
Rats had femoral artery FMD measured before and at multiple time points after exposure to marijuana secondhand smoke at concentrations matching real-world tobacco SHS conditions. Multiple conditions were tested: regular marijuana, cannabinoid-free marijuana, marijuana without rolling paper, tobacco, and chamber air (control). FMD and nitroglycerin-mediated dilation were used to distinguish endothelium-dependent from independent effects.
Why This Research Matters
As marijuana legalization expands, the assumption that marijuana secondhand smoke is harmless is increasingly relevant. This study demonstrates that marijuana smoke impairs blood vessel function through the same mechanism as tobacco smoke but with longer-lasting effects, challenging the notion that marijuana SHS is benign.
The Bigger Picture
Public health debates about whether smoke-free laws should include marijuana often assume that marijuana smoke is fundamentally different from tobacco smoke. This study shows they cause the same type of cardiovascular damage through combustion products, and that marijuana smoke may actually be worse in terms of recovery time.
What This Study Doesn't Tell Us
This was a rat study, and the vascular response may differ in humans. The exposure was acute (one minute), and chronic effects were not studied. FMD is a marker of endothelial function, and the link between acute FMD impairment and long-term cardiovascular disease requires further investigation. The concentrations used matched tobacco SHS conditions but may not represent all marijuana smoke exposure scenarios.
Questions This Raises
- ?Does chronic exposure to marijuana secondhand smoke increase cardiovascular disease risk?
- ?Would vaporized cannabis have the same vascular effects?
- ?Why does marijuana smoke impairment last longer than tobacco smoke impairment?
- ?Should smoke-free laws explicitly include marijuana?
Trust & Context
- Key Stat:
- 1 minute of marijuana SHS impaired blood vessel function for 90+ minutes, longer than tobacco SHS.
- Evidence Grade:
- Moderate evidence from a well-designed animal study with multiple control conditions, published in the Journal of the American Heart Association.
- Study Age:
- Published in 2016. The cardiovascular effects of marijuana smoke continue to be studied as legalization expands.
- Original Title:
- One Minute of Marijuana Secondhand Smoke Exposure Substantially Impairs Vascular Endothelial Function.
- Published In:
- Journal of the American Heart Association, 5(8) (2016)
- Authors:
- Wang, Xiaoyin, Derakhshandeh, Ronak(2), Liu, Jiangtao(2), Narayan, Shilpa, Nabavizadeh, Pooneh, Le, Stephenie, Danforth, Olivia M, Pinnamaneni, Kranthi, Rodriguez, Hilda J, Luu, Emmy, Sievers, Richard E, Schick, Suzaynn F, Glantz, Stanton A, Springer, Matthew L
- Database ID:
- RTHC-01296
Evidence Hierarchy
Tests effects in animals (usually mice or rats), not humans.
What do these levels mean? →Frequently Asked Questions
Is marijuana secondhand smoke harmful?
This study found that just one minute of marijuana secondhand smoke impaired blood vessel function for at least 90 minutes in rats, longer than comparable tobacco exposure. The damage was caused by combustion products, not by THC or CBD, meaning any smoked substance can cause this harm.
Is marijuana smoke as bad as tobacco smoke?
For acute blood vessel damage, this study found marijuana smoke was at least as harmful as tobacco smoke and the effects lasted longer. However, the long-term cardiovascular consequences of chronic marijuana smoke exposure have not been as well studied as tobacco.
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Cite This Study
https://rethinkthc.com/research/RTHC-01296APA
Wang, Xiaoyin; Derakhshandeh, Ronak; Liu, Jiangtao; Narayan, Shilpa; Nabavizadeh, Pooneh; Le, Stephenie; Danforth, Olivia M; Pinnamaneni, Kranthi; Rodriguez, Hilda J; Luu, Emmy; Sievers, Richard E; Schick, Suzaynn F; Glantz, Stanton A; Springer, Matthew L. (2016). One Minute of Marijuana Secondhand Smoke Exposure Substantially Impairs Vascular Endothelial Function.. Journal of the American Heart Association, 5(8). https://doi.org/10.1161/JAHA.116.003858
MLA
Wang, Xiaoyin, et al. "One Minute of Marijuana Secondhand Smoke Exposure Substantially Impairs Vascular Endothelial Function.." Journal of the American Heart Association, 2016. https://doi.org/10.1161/JAHA.116.003858
RethinkTHC
RethinkTHC Research Database. "One Minute of Marijuana Secondhand Smoke Exposure Substantia..." RTHC-01296. Retrieved from https://rethinkthc.com/research/wang-2016-one-minute-of-marijuana
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.