Ducey also challenged the idea that marijuana is a safer substance than alcohol.
"I would check your facts when you say something is not addictive, that something’s safer than alcohol," he said.
Ducey didn't give specifics about the relative dangers of marijuana and alcohol, but we here at Wonkblog always enjoy a drug policy fact check, so we're happy to indulge the governor's request.
Here's what the research has to say.
1. Is marijuana addictive?
Short answer: yes. The best available research indicates that roughly 9 percent of people who use marijuana — 1 in 11 — will eventually become dependent on it. Starting marijuana use in your teens roughly doubles the risk of dependency, at 17 percent.
It's worth pointing out that the study those numbers come from found a similar risk of dependency for drinkers who started in their teens, and higher rates of dependency for drinkers who began in adulthood. And dependency rates for tobacco were higher across the board.
2. Is marijuana safer than alcohol?
This is a much more complicated question. The short answer, again, is "yes," but there's more nuance here.
For starters, as noted above, marijuana users are less likely to become dependent on the drug than drinkers. Overall, research suggests that 15 percent of drinkers become dependent on alcohol.
Marijuana is also considerably less toxic to the human body than alcohol. Compared to marijuana, there's a much smaller difference between a "recreational dose" of alcohol and a "fatal dose." If, say, five shots get you drunk, 15 could kill you.
Marijuana impairs people differently than alcohol does, too. Federal crash data show that the odds of getting into a car accident jump dramatically after a person has been drinking alcohol. The odds don't change much after smoking weed. Other research has shown similar findings.
Alcohol also appears to be much more closely linked to violent behavior than marijuana is. Researchers Mark Kleiman, Jonathan Caulkins and Angela Hawken summed up the literature on drugs and violence in 2011: "Most illicit substances have a much weaker link to violence than alcohol does. ... There is little direct association between marijuana or opiate use and violent crime."
For all of the reasons above, many drug policy experts agree that, on balance, marijuana is less harmful to both individuals and society than alcohol. That was the conclusion reached by a group of researchers for an article in the Lancet in 2010, which graded several common drugs on 16 potential harms to users or society.
But just because marijuana is safer than alcohol doesn't mean that it is safe, full stop. Some research has linked marijuana use to a number of negative physical and mental health outcomes, like a heightened risk of psychosis and the potential for long-term cognitive impairment. Those risks appear to increase for people who use the drug heavily and for those who start using it in their teens.
Some researchers also say that the perennial debate on the relative harm posed by marijuana and alcohol is incomplete. Jonathan Caulkins of Carnegie Mellon University prefers to say that "marijuana is safer than alcohol, but it is also more likely to harm its users."
Caulkins points out that federal survey data show that current marijuana users are more likely (21 percent) to meet diagnostic criteria for abuse or dependence on the drug than current alcohol users (13 percent).
"While alcohol is more dangerous in terms of acute overdose risk, and also in terms of promoting violence and chronic organ failure, marijuana — at least as now used in the United States — creates higher rates of behavioral problems, including dependence, among all its users," Caulkins wrote for the magazine National Affairs earlier this year.
Of course, some of those signs of abuse or dependency (trouble with the law related to the drug or problems at work, home, school or with friends), could be direct consequences of the drug's illegal status. So it's difficult to compare apples to apples on that measure.
So in conclusion, marijuana is addictive, although less so than alcohol. And very broadly speaking it is safer than alcohol, but it still poses a number of risks to its users.
In July, one poll showed only 39 percent of likely voters said they'd vote to legalize marijuana in November. But Arizona voters might be warming up to the idea of recreational pot, according to an Arizona Republic/Morrison/Cronkite News poll conducted in the second half of August. In those results, released Wednesday, 50 percent of registered voters said they were likely to vote in support of the measure.
In response to a Washington Post inquiry, a spokesman for Ducey said that "the governor stands by his position, and believes the facts speak for themselves on this topic when you look at the unintended consequences in Colorado and Washington."