Marijuana is legal in some states, but it may be harmful to children.

That’s the message delivered in a report released today by the American Academy of Pediatrics (AAP).

The organization urged doctors to warn parents that the drug may be harmful to children, even though it might seem acceptable, safe, and therapeutic.

“Marijuana is not a benign drug, especially for teens. Their brains are still developing, and marijuana can cause abnormal and unhealthy changes,” Dr. Seth D. Ammerman, FAAP, co-author of the AAP report, said in a statement.

As it stands, 29 states have legalized some form of marijuana use. Eight states, along with the District of Columbia, have made recreational marijuana legal for adults over the age of 21. The other states have legalized medical marijuana.

Young people using marijuana regularly can experience decreased sensory awareness, weakened motor skill control and memory function, and impaired lung function.

The drug is also tied to mental disorders including psychosis, depression, and addiction, the AAP report states.

Read more: Marijuana addiction is rare but real »

Specific concerns

Much of the concern about marijuana’s harmfulness is due to the increase in the concentration of tetrahydrocannabinol (THC), which is a psychoactive substance in the plant.

In the United States, the amount of THC found in marijuana surged from 4 percent in 1995, to 12 percent in 2014. Some strains have as much as 20 percent THC.

This chemical is the same one that can lower pain and ease chemotherapy side effects.

The AAP is urging doctors to talk about using marijuana as well as screening kids for substance abuse. Parents who use it may not know about the impacts it can have on children, they say.

“Seeing parents use marijuana makes kids more likely to use it themselves, whether or not their parents tell them not to, because actions speak louder than words,” Dr. Sheryl A. Ryan, lead author of the report, said in a statement.

Read more: Marijuana use has doubled in U.S. since 2001 »

How kids perceive marijuana

In 2015, 7 percent of children aged 12 to 17 used marijuana.

The percentage of adolescent marijuana users was similar to percentages between 2004 and 2014.

Studies have shown that 9 percent of people who try marijuana become addicted to it. That number rises to 17 percent when the user starts during adolescence. It goes up to 50 percent among teens that consume marijuana on a daily basis.

Correlating usage to confirm whether or not there has been an increase in use after a state legalizes the drug is where experts seem to disagree.

The AAP cited a National Survey on Drug Use and Health report that found the percentage of 12- to 17-year-olds who said there was a great risk to using marijuana decreased from 55 percent in 2007 to 41 percent in 2015.

A Centers for Disease Control and Prevention (CDC) report of National Survey on Drug Use and Health (NSDUH) data states that the percentage of kids 12 to 17 who perceived the greatest risk from using it declined from 34 percent in 2006 to 24 percent in 2013.

Read more: Colorado marijuana engineered to get you higher »

More legalization, more use?

Natalie Lyla Ginsberg, the policy and advocacy manager of the Multidisciplinary Association for Psychedelic Studies (MAPS), told Healthline that she was disappointed in the AAP’s “alarmist warning and avoidance of research.”

Ginsberg cited a National Academy of Medicine report that found heavy cannabis use among 12- to 17-year-olds was at 7 percent. A 2013 study mentioned in that report states that users were declining compared with older adults.

A 2016 CDC report stated that that cannabis use has declined among 12- to 17-year-olds since 2002. The report cites that kids 12 to 17 who used marijuana in the past month went up from 6.7 percent in 2006 to 7.1 percent in 2013.

Ginsberg noted that Colorado’s data indicates that teen marijuana use went down in the state since legalization.

Kyle Sherman, chief executive officer of the point-of-sale tool Flowhub, told Healthline that his platform is geared at keeping minors out of dispensaries.

“Here in Colorado we've seen no increase in teen use since legalization,” Sherman said.

He believes regulating cannabis will help get it off the streets and out of children’s hands.

“There is no convincing evidence that cannabis use alone is harmful for children, but we also do not have enough research to assert that that means it is therefore safe,” Ginsberg added. “However, we do have research that medical cannabis is far safer than many less effective and more dangerous pharmaceuticals often prescribed for children.”

She also noted that many of the AAP’s assertions about health impacts of marijuana on children do not take into account the whole picture. The AAP should focus screening on trauma and other stressors to children, instead of solely focusing on symptoms of trauma such as substance abuse, Ginsberg said.

Dr. Guohua Li, a professor of epidemiology at Columbia University, said the AAP’s concerns and warning are justified.

“As a parent, I'm grateful to AAP for safeguarding the safety, health, and well-being of our children,” Li told Healthline. “There is an urgent need for federal, state, and local government agencies to monitor marijuana use and related consequences in children.”

Li notes that the jury is still out as to whether legalization has caused an increase in marijuana use among kids, but there is mounting evidence that access to edibles has increased in children. A 2016 study in JAMA Pediatricsfound an increase in children being exposed to the drug in Colorado, where edibles are legal.

Read more: If marijuana is medicine, why can’t we buy it in pharmacies? »

What’s next?

Dr. Marcus Bachhuber, an assistant professor of medicine at the Albert Einstein College of Medicine in New York, said that because legalization is a reality, it’s time to focus on how to regulate marijuana programs.

“How best can we allow access for patients who could benefit while protecting kids and promoting public health?” he told Healthline. “Physicians have a key role to play in shaping policy and the overall debate, but all too often, we have decided to watch from the sidelines.”

The AAP’s report comes about a week after President Donald Trump’s press secretary Sean Spicer spoke about cracking down on marijuana regulations.

While the president has said he approves of medicinal uses, federal laws still consider marijuana use to be illegal.