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One Minute of Marijuana Secondhand Smoke Exposure Substantially Impairs Vascular Endothelial Function

View Article: PubMed Central - PubMed

ABSTRACT

Background: Despite public awareness that tobacco secondhand smoke (SHS) is harmful, many people still assume that marijuana SHS is benign. Debates about whether smoke‐free laws should include marijuana are becoming increasingly widespread as marijuana is legalized and the cannabis industry grows. Lack of evidence for marijuana SHS causing acute cardiovascular harm is frequently mistaken for evidence that it is harmless, despite chemical and physical similarity between marijuana and tobacco smoke. We investigated whether brief exposure to marijuana SHS causes acute vascular endothelial dysfunction.

Methods and results: We measured endothelial function as femoral artery flow‐mediated dilation (FMD) in rats before and after exposure to marijuana SHS at levels similar to real‐world tobacco SHS conditions. One minute of exposure to marijuana SHS impaired FMD to a comparable extent as impairment from equal concentrations of tobacco SHS, but recovery was considerably slower for marijuana. Exposure to marijuana SHS directly caused cannabinoid‐independent vasodilation that subsided within 25 minutes, whereas FMD remained impaired for at least 90 minutes. Impairment occurred even when marijuana lacked cannabinoids and rolling paper was omitted. Endothelium‐independent vasodilation by nitroglycerin administration was not impaired. FMD was not impaired by exposure to chamber air.

Conclusions: One minute of exposure to marijuana SHS substantially impairs endothelial function in rats for at least 90 minutes, considerably longer than comparable impairment by tobacco SHS. Impairment of FMD does not require cannabinoids, nicotine, or rolling paper smoke. Our findings in rats suggest that SHS can exert similar adverse cardiovascular effects regardless of whether it is from tobacco or marijuana.

No MeSH data available.


Related in: MedlinePlus

Smoke exposure chamber showing lack of visible smoke. Yellow arrows designate the corners of the exposure chamber. Double‐headed orange arrows show depth of chamber, ≈30 cm.
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jah31602-fig-0007: Smoke exposure chamber showing lack of visible smoke. Yellow arrows designate the corners of the exposure chamber. Double‐headed orange arrows show depth of chamber, ≈30 cm.

Mentions: A limitation of the study is that the typical ambient levels of marijuana SHS have not been systematically measured in real‐world situations, in contrast to what is known about tobacco SHS. The exposure levels of tobacco SHS on which our conditions were based can reasonably be expected to exist for marijuana SHS at parties, rock concerts, and other situations in which multiple people are smoking marijuana at any given time, but this remains unconfirmed. Our understanding of the relative risks of exposure in different social situations would benefit greatly from a comprehensive study of particle levels under these circumstances. Nonetheless, the smoke concentrations in our study were low enough that the smoke was not visible during the exposures in the clear exposure chamber (Figure 7).


One Minute of Marijuana Secondhand Smoke Exposure Substantially Impairs Vascular Endothelial Function
Smoke exposure chamber showing lack of visible smoke. Yellow arrows designate the corners of the exposure chamber. Double‐headed orange arrows show depth of chamber, ≈30 cm.
© Copyright Policy - creativeCommonsBy-nc-nd
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5015303&req=5

jah31602-fig-0007: Smoke exposure chamber showing lack of visible smoke. Yellow arrows designate the corners of the exposure chamber. Double‐headed orange arrows show depth of chamber, ≈30 cm.
Mentions: A limitation of the study is that the typical ambient levels of marijuana SHS have not been systematically measured in real‐world situations, in contrast to what is known about tobacco SHS. The exposure levels of tobacco SHS on which our conditions were based can reasonably be expected to exist for marijuana SHS at parties, rock concerts, and other situations in which multiple people are smoking marijuana at any given time, but this remains unconfirmed. Our understanding of the relative risks of exposure in different social situations would benefit greatly from a comprehensive study of particle levels under these circumstances. Nonetheless, the smoke concentrations in our study were low enough that the smoke was not visible during the exposures in the clear exposure chamber (Figure 7).

View Article: PubMed Central - PubMed

ABSTRACT

Background: Despite public awareness that tobacco secondhand smoke (SHS) is harmful, many people still assume that marijuana SHS is benign. Debates about whether smoke‐free laws should include marijuana are becoming increasingly widespread as marijuana is legalized and the cannabis industry grows. Lack of evidence for marijuana SHS causing acute cardiovascular harm is frequently mistaken for evidence that it is harmless, despite chemical and physical similarity between marijuana and tobacco smoke. We investigated whether brief exposure to marijuana SHS causes acute vascular endothelial dysfunction.

Methods and results: We measured endothelial function as femoral artery flow‐mediated dilation (FMD) in rats before and after exposure to marijuana SHS at levels similar to real‐world tobacco SHS conditions. One minute of exposure to marijuana SHS impaired FMD to a comparable extent as impairment from equal concentrations of tobacco SHS, but recovery was considerably slower for marijuana. Exposure to marijuana SHS directly caused cannabinoid‐independent vasodilation that subsided within 25 minutes, whereas FMD remained impaired for at least 90 minutes. Impairment occurred even when marijuana lacked cannabinoids and rolling paper was omitted. Endothelium‐independent vasodilation by nitroglycerin administration was not impaired. FMD was not impaired by exposure to chamber air.

Conclusions: One minute of exposure to marijuana SHS substantially impairs endothelial function in rats for at least 90 minutes, considerably longer than comparable impairment by tobacco SHS. Impairment of FMD does not require cannabinoids, nicotine, or rolling paper smoke. Our findings in rats suggest that SHS can exert similar adverse cardiovascular effects regardless of whether it is from tobacco or marijuana.

No MeSH data available.


Related in: MedlinePlus