As weed enthusiasts around the world celebrate 4/20, a new report from the Colorado Department of Public Safety found that emergency-room visits related to marijuana are up and pot use among young adults is on the rise — though the decreased stigma surrounding recreational cannabis is blunting its findings.

Since becoming the first state to legalize recreational marijuana, in 2014, ER visits related to pot use have increased by nearly 30 percent in Colorado, the study found. From 2014 to mid-2015, 956 out of every 100,000 ER visits (roughly one out of every 1,000) were related to marijuana use, compared to 739 per 100,000 from 2010 through 2013.

Similarly, hospitalizations related to cannabis use increased from 803 per 100,000 (from 2001 to 2009) to 2,413 per 100,000 from January 2014 through June 2015.

And while the number of people seeking treatment for marijuana abuse was virtually unchanged in the first year of legalization, those that did seek treatment reported heavier use. The report shows that more than a third of patients (35.6 percent) in drug treatment centers reported near daily use of marijuana in 2014, compared to 33.5 percent in 2013, 32.2 percent in 2012 and 30 percent in 2011.

But such statistics come with a major caveat. According to the report:







The decreasing social stigma regarding marijuana use could lead individuals to be more likely to report use on surveys and to health workers in emergency departments and poison control centers, making marijuana use appear to increase when perhaps it has not.



In other words, people may feel more comfortable discussing their cannabis use than they were when the drug was illegal.



Partygoers smoke marijuana during a New Year's Eve party celebrating the start of retail pot sales in Denver, Dec. 31, 2013. (Brennan Linsley/AP)

Among the 143-page report’s other findings:

• Marijuana arrests are down. The total number of arrests for the possession or sale of marijuana fell 46 percent between 2012 and 2014. Arrests for possession, which make up the majority of pot arrests in the state, were cut nearly in half, while arrests for marijuana sales fell 24 percent.

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• Pot-related DUIs are down slightly. According to the Colorado State Patrol, the number of summonses issued for driving under the influence in which marijuana was a factor dipped 1 percent between 2014 and 2015 (674 to 665).

• Driving deaths are up, but not necessarily from pot impairment. The number of fatalities for drivers who had THC in their system increased 44 percent, from 55 in 2013 to 79 in 2014. But “the detection of THC in blood is not an indicator of impairment but only indicates presence in the system.”

• The impact of legalization on kids is unclear. The number of juvenile marijuana arrests increased 5 percent, with 3,400 in 2014 compared to 3,234 in 2012. But a pair of youth surveys had conflicting results, with one showing students who reported using marijuana within the past 30 days on the decline (a Healthy Kids Colorado Survey found 80 percent of high school students did not use marijuana in the 30 days prior to being surveyed) and another showing the use of pot among Colorado kids above the national average. “The perception of health risk of using marijuana is declining among youth in Colorado,” the report states.

• Heavy pot use among young adults is on the rise. According to the National Survey on Drug Use and Health, the current prevalence rates for marijuana use in the past 30 days have increased significantly for 18-to-25-year-olds in the past decade. In 2006, 21 percent reported having consumed pot in the 30 days prior to being surveyed. In 2014, nearly a third (31 percent) of 18-to-25-year-old Coloradans did.

“The finding is among a growing body of evidence that marijuana legalization has led to a shift in use patterns for at least some cannabis consumers,” the Denver Post said.

The paper called the report — which was mandated by the state when it voted to legalize marijuana — the “first comprehensive attempt at measuring and tracking the consequences of legalization” in Colorado. But according to Jack Reed, the statistical analyst who authored it, the study should be viewed simply as a starting point because of a lack of historical data.

“It is too early to draw any conclusions about the potential effects of marijuana legalization or commercialization on public safety, public health, or youth outcomes,” Reed writes, “and this may always be difficult.”