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High Carbon Monoxide Levels from Charcoal Combustion Mask Acute Endothelial Dysfunction Induced by

Hookah (Waterpipe) Smoking in Young Adults.

Circulation. 2019 Feb 15. doi: 10.1161/CIRCULATIONAHA.118.037375. [Epub ahead of print]

High Carbon Monoxide Levels from Charcoal Combustion Mask Acute Endothelial DysfunctionInduced by Hookah (Waterpipe) Smoking in Young Adults. Rezk-Hanna M1, Mosenifar Z2, Benowitz NL3, Rader F4, Rashid M4, Davoren K4, Moy NB4, Doering L5, Robbins W6, Sarna L1, Li N7, Chang LC8, Elashoff RM9, Victor RG10. Author information 1School of Nursing, University of California, Los Angeles, CA.2Division of Pulmonary and Critical Care Medicine, Cedars Sinai Medical Center, CA.3Division of Clinical Pharmacology and Experimental Therapeutics, University of California, San Francisco, CA.4Smidt Heart Institute, Cedars-Sinai Medical Center, CA.5School of Nursing, UCLA, CA.6Fielding School of Public Health/School of Nursing, University of California Los Angeles, CA.7Biomathematics, University of California, Los Angeles, CA.8Biomathematics, University of California Los Angeles, CA.9Biomath, University of California Los Angeles, CA.10Cedars-Sinai Smidt Heart Institute, CA. Abstract BACKGROUND: Hookah smoking is marketed to youth as a harmless alternative to cigarettes. While cigarette smoking acutely impairs endothelial function, the effect of smoking fruit flavored hookah tobacco is unknown. Because charcoal traditionally is used to heat the hookah tobacco in the waterpipe, hookah smoke delivers tobacco toxicants and nicotine plus charcoal combustion products: not only carbon-rich nanoparticles-oxidants that may destroy nitric oxide and impair endothelial function-but also large amounts of carbon monoxide (CO), a putative vasodilator molecule. METHODS: To test the acute effect of hookah smoking on endothelial function, in young adult hookah smokers (n=30, age 26±1 years, mean ±SE), we measured plasma nicotine, exhaled CO, and brachial artery flow-mediated dilation (FMD) before and after charcoal-heated hookah smoking. To remove the effect of charcoal combustion, the same measurements were performed when the same flavored hookah tobacco product was heated electrically (n=20). As a positive internal control, we studied age-matched cigarette smokers (n=15) who smoked one cigarette. To isolate the effect of the CO boost on FMD, hookah smokers (n=8) inhaled a 0.1% CO gas mixture to approximate their CO boost achieved with charcoal-heated hookah smoking. RESULTS: Nicotine levels increased similarly with all types of smoking, while exhaled CO increased 9- to 10-fold more after charcoal-heated hookah than after either electrically-heated hookah or cigarette smoking. FMD did not decrease after smoking charcoal-heated hookah but instead increased by +43±7% (p<0.001). In contrast, FMD decreased by -27±4% (p<0.001) after smoking electrically-heated hookah, comparable to the decrease after cigarette smoking. FMD increased markedly by 138±71% (p<0.001) after breathing CO gas-2.8 times more than the increase induced in the same subjects after smoking charcoal-heated hookah (p<0.001)-despite comparable increases in exhaled CO (24±1 vs. 28±3 PPM, hookah vs. CO). CONCLUSIONS: Smoking hookah tobacco, similar to cigarette tobacco, acutely impairs endothelial function. With traditional charcoal-heated hookah smoking, the acute endothelial dysfunction is masked by high levels of carbon monoxide, a potent vasodilator molecule generated by charcoal combustion. With respect to large artery endothelial function, smoking hookah is not harmless. CLINICAL TRIAL REGISTRATION: URL: Unique identifiers: NCT 03616002 and NCT 03067701. KEYWORDS: carbon monoxide; hookah; waterpipe

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