Experts from the vast spectrum of marijuana research gathered Friday to discuss the medical and public policy implications of Colorado’s new cannabis laws, focusing strongly on the drug’s impact on children.
“We are here to examine the evidence,” said moderator Tim Byers, M.D., associate dean of the Colorado School of Public Health, which sponsored the Marijuana and Public Health Symposium held at Mile High Station near the CU Denver campus.
Nearly 350 people attended.
The researchers quickly dismissed notions that marijuana was harmless, presenting studies showing links to cancer, lung disease, lower IQs and potential impacts on fetal health. At the same time, they pointed out the shortcomings of current research and the need for more robust studies in the future.
“There is this assumption that since marijuana is legal, everyone knows what it is,” said Amanda Reiman, Ph.D., California Policy Manager for the Drug Policy Alliance. “But what is this plant? Where does it come from? The truth is, cannabis is as old as time. The therapeutic use goes back to 2800 B.C. Its history as a recreational drug is short compared to its use as a therapeutic agent.”
Known simply as cannabis for years, Mexican immigrants to the U.S. dubbed it “marijuana” in the 1930s and the name stuck, Reiman said. “What we have today is a whole load of marijuana hybrids, hundreds of strains that are a mix of ancient varieties of cannabis,” she said. “Each plant has over 600 chemicals and 70 cannabinoids.”
She noted that while cannabis “cannot be fatal” it’s not without risk.
Some of those risks were illuminated by Daniel Bowles, M.D., a medical oncologist at the University of Colorado Hospital and the Denver VA Medical Center.
Bowles said marijuana smoke can induce precancerous changes in the respiratory mucosa of rats. He also cited a study of Swedish military conscripts, showing that those who smoked the highest quantities of marijuana had a 2.1 percent increase in lung cancer. Another study linked marijuana smoke to oropharyngeal cancers. There were also associations with certain kinds of testicular cancers.
“There is no research on edible or topical marijuana at this point for cancer,” he said.
The evidence linking marijuana use to heart and lung disease was less compelling.
“There is some evidence associating marijuana use with heart attack and stroke but it’s very limited,” said David Goff, M.D., dean of the Colorado School of Public Health. “Chronic use has been associated with bronchitis but not emphysema.”
One of the most powerful presentations was made by Paula Riggs, M.D., director of the division of substance abuse at the University of Colorado School of Medicine.
“We know that early substance abuse can lead to mental health issues later. We know that cannabis is really neurotoxic to childhood brain development,” she said. “Heavy use can lead to a reduction in six to eight IQ points. It is also connected to persistent deficits in reading, learning, abstract reasoning and is associated with early onset depression, especially in boys, by age 10.”
Riggs said one in 11 adults who try marijuana will become dependent, while one in six adolescents will do the same.
“It matters what kids are involved with during adolescence since their brains are under construction in a big way,” she said.
Protecting children was a major theme of the symposium. Public health officials talked about meeting high school students convinced marijuana was harmless or made them drive better.
Laura Borgelt, associate professor at the CU Skaggs School of Pharmacy and Pharmaceutical Sciences, said marijuana passes easily from the placenta to the fetus where it is stored in fat cells.
It also moves from the mother to the baby through breast milk.
“THC (the active ingredient in marijuana) is excreted in human milk in moderate amounts,” she said.
Borgelt said pregnant women who use marijuana need to be educated about the potential risks to the development of their fetus. Other experts say if women are using cannabis they shouldn’t breastfeed.
“Babies are full of fat so they are essentially storage chambers for marijuana,” Borgelt said.
George Sam Wang, M.D., an emergency room physician at Children’s Hospital Colorado, has done studies showing a steep increase in children being treated in emergency rooms after eating marijuana-laced brownies, cookies and other edibles since medical marijuana was legalized in 2009.
Children show up suffering from extreme drowsiness, lethargy and respiratory problems. One boy recently had to be intubated after he stopped breathing.
“Edible products pose a unique issue for unintentional pediatric exposures,” Wang told the audience. “The answer is child-resistant packaging. Right now the best thing is proper storage. Keep it out of reach and out of sight.”
Aside from the medical issues, there are myriad public policy and safety questions surrounding marijuana.
Law enforcement is still struggling to come up with an accurate way to measure “drugged driving.”
“Unlike alcohol, there is no clean relationship between THC levels in the blood and physiological effects,” said Ashley Brooks-Russell, Ph.D., MPH, assistant professor at the Colorado School of Public Health. “Some still believe the myth that people drive better when they are high. There is no evidence or any biological possibility that this is true.”
Larry Wolk, M.D., chief medical officer and executive director of the Colorado Dept. of Public Health and Environment, said new marijuana laws are creating a host of challenges.
Waste disposal is an issue, quality control questions surround the pot being sold, monitoring the plants is a challenge and then there is the health threat posed by synthetic marijuana.
“This is an issue that touches and will continue to touch on so many aspects of public health,” Wolk said. “My title is chief medical officer but sometimes I think I’m really chief marijuana officer.”