MedicalResearch.com Interview with: [caption id="attachment_68847" align="alignleft" width="150"] Dr. Springer[/caption] Matthew L. Springer, Ph.D. Associate Professor of Medicine Division of Cardiology Cardiovascular Research Institute Broad Center of Regeneration Medicine and Stem Cell Research Center for Tobacco Control Research & Education Helen Diller Family Comprehensive Cancer Center University of California, San Francisco MedicalResearch.com: What is the background for this study? Response: It's been known for many years that chronic tobacco smokers have poor endothelial function, even if they have not smoked recently, and so do non-smokers who are frequently exposed to secondhand smoke.  Endothelial dysfunction, even in otherwise outwardly healthy people, is an indication of unhealthy arteries and increased risk of cardiovascular disease later in life.  I realized that many people who would presumably avoid secondhand smoke did not mind it if it came from cannabis, and I wondered if that could be true since both kinds of smoke included the thousands of chemicals that resulted from burning plant material. A number of years ago, we developed a way to study changes in endothelial function in rats, using a technique very similar to how we measure it in humans, and we saw that, as in humans, even brief exposures to secondhand smoke from tobacco impaired vascular function in the rats.  We subsequently showed that brief exposures to secondhand smoke from marijuana, and active smoking of marijuana, similarly impaired vascular function in the rats, even if the smoke was from marijuana lacking THC and the other cannabinoids.  That again raised the question of whether the endothelial dysfunction observed in human tobacco smokers would also occur in human marijuana smokers, and whether secondhand smoke from marijuana should be avoided like secondhand smoke from tobacco. These questions form the basis of our current study..  In our study, it is quite clear that chronic cannabis smokers had endothelial dysfunction similar to that of chronic tobacco smokers.  Whether frequent exposure to secondhand marijuana smoke similarly impairs endothelial function like secondhand tobacco smoke is still unknown, and that's one of the major questions we want to answer next.