Monitoring potential public-health outcomes was a top priority for state health officials after Colorado implemented its recreational marijuana law in 2014.
Three years into regulated sales of recreational cannabis, the Retail Marijuana Public Health Advisory Committee says calls to poison control and marijuana-related emergency room visits are down, even though overall consumption of pot remains steady — signs that existing policy and education efforts may be working.
“I think that speaks to a learning effect,” Mike Van Dyke, chief of Colorado’s Environmental Epidemiology, Occupational Health and Toxicology branch, said referring to the decline in ER visits and poison center calls. “The public is really learning the message, if not from us, from their own experience.”
Van Dyke is chairman of the 14-member committee, which on Tuesday released its second batch of data around the public health effects of marijuana in Colorado. The first report, released in January 2015 by a panel of doctors, scientists and public health officials, contained what state officials described as “baseline data.”
“We are doing our best to study this closely and monitor what’s going on,” he said. “While maybe not apparent from this report, we are taking this evidence base that we’re developing, and we are using it to develop prevention campaigns, education campaigns. We are doing our best to implement an evidence-based policy.”
The sweeping report delves into state and federal data covering topics such as usage rates among different populations, hospital visits, drugged driving and health effects.
Among the results Van Dyke said are encouraging, are findings that marijuana use among high school students has not seen statistical increases. About 21 percent of Colorado high school students had used marijuana in 2015, compared with 20 percent in 2013 and about 17 percent nationally.
“We’ve had a pretty good history on high school use, but we didn’t start asking the questions about marijuana use — unfortunately until after legalization — for adults,” Van Dyke said.
The data also lend guidance as to areas to closely monitor. In addition to usage rates, health officials’ concerns include marijuana use during pregnancy and negative consequences of marijuana in households with children.
A quick snapshot of the results reveal:
- Past-month marijuana use among Colorado adults did not change from 2014 to 2015. However, the percentage of Coloradans who said they use cannabis — 13 percent and 17 percent according to two separate federal surveys — is higher than the national average of 8 percent.
- The vast majority of past-month marijuana users — 79 percent — chose to smoke their cannabis. The percentage of those who vaped or consumed edibles was 30 percent and 33 percent, respectively. (Respondents could also pick more than one method.)
- The past-month marijuana use of Colorado adults in 2015 was highest among Colorado males, at 26 percent, those between the ages of 18 to 25, at 17 percent, and those who identified as gay, lesbian, bisexual or another sexual orientation, at 37 percent. Marijuana use was also higher among gay, lesbian or bisexual teens as opposed to those who identified as heterosexual.
- Past-month marijuana use among teens was relatively unchanged and in line with the national average.
- Marijuana is not Colorado adults’ drug of choice: About 6 percent of those surveyed said they used marijuana daily or near-daily. That compares to 16 percent for daily or near-daily tobacco use and 22 percent for daily or near-daily alcohol use.
- Poison center calls about marijuana exposure have been on the decline since 2015 and marijuana-related emergency room visits dropped between 2014 and 2015, according to the report. Hospital data from 2016 was not yet available.
- 6 percent of women in Colorado used marijuana during their pregnancy — 2 percentage points higher than the national average.
- 7.9 percent of adults with children between the ages of 1 and 14 kept marijuana in or around the home, according to the report. In 18 percent of these households — about 14,000 homes — marijuana was potentially unsafely stored.
- From 2014 to 2015, children between 1 and 14 in about 16,000 homes had secondhand exposure to marijuana.
The panel also reviewed existing scientific literature on the potential health effects of marijuana. The committee came to several conclusions similar to those made by the National Academies of Sciences, Engineering and Medicine, which earlier this month released its most comprehensive study in decades on marijuana.
Among the findings of the RMPHAC:
- Substantial and moderate evidence that teens and young adults who use marijuana are more likely to experience impaired memory and cognitive function, and are at greater risk for developing psychotic symptoms and marijuana dependency as adults.
- Strong evidence that marijuana smoke contains many of the same cancer-causing chemicals found in tobacco smoke. Research is conflicting as to whether heavier smokers of marijuana could develop lung cancer.
- Moderate level of scientific evidence that marijuana use increases risk for some forms of stroke in individuals younger than 55.
- Credible evidence of clinically important drug interactions between marijuana and medications such as some anti-seizure medications and a common blood-thinner.
- Risk of a motor vehicle crash increases among drivers with recent marijuana use. The higher the blood THC level, the higher the motor vehicle crash risk.
- Strong evidence shows that daily or near-daily marijuana users are likely to have impaired memory lasting a week or more after quitting.