PORTLAND — A federal study on teen drug use — showing increased marijuana use among eighth- and 10th-graders — is being used by Maine legalization advocates and their opponents alike to bolster their respective cases.

In November, Portland voters overwhelmingly approved an ordinance legalizing possession of small amounts of pot for nonmedical uses, making Maine’s largest city the first on the East Coast to legalize recreational marijuana.

Proponents of that measure, such as the Marijuana Policy Project, have been clear that they see Portland as a launchpad for a statewide legalization referendum in 2016.

On Wednesday, the National Institute on Drug Abuse released the results of its annual Monitoring the Future study of U.S. students, showing that use of cigarettes and alcohol by respondents in the eighth, 10th and 12th grades has decreased over the past year.

Conversely, “current” marijuana use — defined as use within the past 30 days — has risen in two of the three surveyed grade levels. According to the report, 7 percent of eighth-graders have used pot within the previous 30 days, compared with 6.5 percent last year. Among 10th-graders, the year-to-year jump was from 17 percent to 18 percent.

Only high school seniors were slightly less likely to have used marijuana than the previous year, with 22.7 percent saying they used pot within 30 days in 2013, compared with 22.9 percent in 2012.

But even the seniors showed an increase when looking at longer-term numbers, the organization Project SAM — Smart Approaches to Marijuana — pointed out Wednesday. About 6.5 percent of 12th-grade respondents said they used pot daily, a nearly 300 percent increase over the 2.3 percent who said that in 1993.

Former U.S. Rep. Patrick Kennedy, D-RI, is co-founder of Project SAM. In a Wednesday announcement, he noted that 60 percent of high school seniors told surveyors they didn’t believe marijuana is harmful.

“The rise of legalization and medical marijuana has sent a message to young people that marijuana use is harmless and non-addictive, contrary to science supported by the American Medical Association, National Institutes of Health and every other major scientific body that has examined the issue,” Kennedy said in a statement.

Marijuana Policy Project representatives, on the other hand, argued that the reason pot use is growing is more likely that it’s not regulated like cigarettes and alcohol are. The NIDA study released Wednesday showed cigarette use dropping by between 0.4 percent and 1.7 percent across the three surveyed grade levels, while alcohol use fell by between 0.8 percent and 2.3 percent.

“The results suggest that regulating alcohol and cigarettes is successfully reducing teen use, whereas marijuana prohibition has been unsuccessful,” Marijuana Policy Project communications director Mason Tvert said in a statement. “At the very least, this data should inspire NIDA to examine the possibility that regulating marijuana like alcohol and cigarettes could be a more effective approach than the current system.”

Both the Marijuana Policy Project and Project SAM are approaching Maine as one of their next key battlegrounds in the debate over marijuana legalization.

State Rep. Diane Russell, D-Portland, sponsored legislation here during the previous session that would have legalized, taxed and regulated pot like cigarettes and alcohol statewide, but the bill did not get past the committee level of review.

In Washington and Colorado, where recreational marijuana has been legalized, the U.S. Department of Justice has indicated it would not interfere, despite federal laws prohibiting pot use, as long as the drug is strictly regulated.

According to the Marijuana Policy Project, which cited a 2012 U.S. Centers for Disease Control and Prevention survey, pot use by Colorado high school students tailed off by 11 percent from 2009 to 2011, the period during which the state began regulating the drug. Nationwide, teen marijuana use increased by about 11 percent over that same stretch of time, the organization asserted.

“Those selling marijuana in the underground market are not asking for ID,” Tvert said. “By regulating marijuana like alcohol and cigarettes and enforcing similar age restrictions, we would very likely see a similar decrease in availability and use among teens.”

Project SAM allies reached different conclusions about the results of marijuana legalization in Washington and Colorado. The group claimed that incidents of marijuana-impaired driving increased by 50 percent in Washington over the past year and that more Colorado youths are seeking substance abuse treatment.

“There is no way to properly ‘regulate’ marijuana without allowing an entire industry to encourage use at a young age, to cast doubt on the science, and to make their products attractive — just like Big Tobacco did for 50 years,” Kevin Sabet, Project SAM director, said in a statement. “Today’s Big Marijuana is no different.”

Dr. Christian Thurstone, president of the Colorado Child and Adolescent Psychiatric Society and a University of Colorado-Denver youth addiction researcher, said his clinic has been “inundated with young people reporting for marijuana-addiction treatment.”

“Every day, we see the acute effects of the policy of legalization,” Thurstone said in a statement distributed by Project SAM. “And kids are paying a great price.”