Millions more Americans now admit to toking up than just three years before.

That conclusion is based on a new Gallup survey, which found the number of Americans admitting to current marijuana use has nearly doubled in just three years. In 2013, 7 percent of US adults responding to Gallup admitted to smoking marijuana. This year, 13 percent did.

As Christopher Ingraham at the Washington Post pointed out, that 13 percent amounts to more than 33 million Americans — more than the population of Texas.

The results could be partly explained by some people being more willing to admit they use pot. Now that multiple surveys show most Americans support legalization, and with several states legalizing the drug, the stigma that used to surround pot has diminished. So perhaps more people now feel okay telling Gallup that yes, they smoke weed — even if they have been using it all their lives.

But some of the increase is likely attributable to more people using the drug, perhaps partly as a result of legalization and its effect on the social stigma.

That isn’t exactly welcome news. While most people can probably use pot without much or any negative impact on their lives, there are a few who will suffer from bad outcomes — including dependence and overuse, accidents, non-deadly overdoses that lead to mental anguish and anxiety, and potentially psychotic episodes. If there’s a rise in overall use, there’s likely a rise in those problematic outcomes, too.

This doesn’t mean that legalizing marijuana — and potentially loosening access to it — is inherently bad. But it does speak to the balancing act that policymakers have to take into account as they reshape marijuana policy for a world in which pot is increasingly legal.

Marijuana legalization is a balancing act

Even if legalization increases levels of pot use, it’s unclear how that may affect society at large. Yet the downsides to not legalizing are definitely big — including more arrests each year over a comparatively mild drug, and more drug-related violence around the world.

In the US, hundreds of thousands of people are arrested for pot possession each year, ripping communities and families apart as people are thrown in jail or prison. There are enormous racial disparities in these arrests, with black people 3.7 times as likely to be arrested for marijuana possession as their white counterparts despite being only 1.3 times as likely to use the drug. And even a simple arrest can stain someone’s criminal record, making it harder to find a job or housing.

Around the world, drug cartels and gangs use profits from marijuana shipped to the US to maintain their stranglehold over trafficking routes, particularly through Latin America. Marijuana sales to the US make up a significant chunk of drug cartels’ drug export revenue: previously as much as 20 to 30 percent, according to estimates from the Mexican Institute of Competitiveness (2012) and the RAND Corporation (2010).

This gave criminal groups more money to carry out violent trafficking operations in much of Latin America, which contribute to the killing and kidnapping of tens of thousands of people each year, and have spawned horrifying stories of cartels beheading and torturing people. And some of that violence occurs in the US, where gangs fight over turf to position themselves to sell illegal drugs.

Full legalization should directly address the problems caused by prohibition. It cuts arrests for marijuana use. And it shifts sales from the black market to the gray market, where people sell legal pot under the table, as well as to the legal market — weakening or even eliminating a major source of revenue for drug cartels and gangs, leaving them less able to continue funding their violent acts.

Of course, all of this comes with the possibility that more people will use marijuana — as the Gallup data may show. And with that increase could come more accidents, more non-deadly overdoses that cause mental anguish, and even psychotic episodes.

But despite those risks, marijuana is a relatively safe drug: Studies show it’s much less likely to cause accidents than more dangerous drugs like alcohol, and there’s little evidence that pot causes severe health problems. So even if cannabis use goes up, it may not make the world much worse.

There are also ways to legalize that would reduce the risks. For example, a report by the RAND Corporation found that states could reduce access and increase prices by allowing only home growing and nonprofit sales, or having state governments directly manage sales like they do under state monopolies of alcohol sales. With these policies, states could minimize the harms of legalization and cut the downsides of prohibition.

Unfortunately, it doesn’t seem that’s what states are doing at all right now: They are following what’s widely known as the “alcohol model” for legalization — in which the drug is easily accessible in retail outlets, with limited state licensing and regulations.

So even though legalization may be better than prohibition, we can still expect some potential bad to come out of it — including, as Gallup’s numbers suggest, higher use.