NEW YORK (CBSNewYork) — The nation’s pediatricians are beefing up their warning about teenagers and marijuana use.

A new report from the American Academy of Pediatrics found as more states legalize the drug for adult use, more teenagers think it’s safe.

“Marijuana is not a benign drug for teenagers because it affects their developing mind. Teenagers are at a critical time of brain development and they have lifelong impacts from marijuana during adolescence,” Dr. Stephen Patrick, Vanderbilt University Medical Center, said.

The report said the drug is more addicting today, it can affect learning and regular use can lead to mental health problems including anxiety and depression.

California and 28 other states allow medical or recreational use of marijuana for adults over 21 and doctors are worried many parents who use the drug may think it’s okay for kids, CBS2’s Chris Martinez reported.

“Parents really need to model behaviors of drug use. To not use substances in front of their children,” Dr. Patrick said.

With about 20 percent of high school students using marijuana, experts said it’s critical for parents and pediatricians to discuss the dangers with kids.

Research showed teenagers who use marijuana are at higher risk of changes in the brain regions that affect memory and IQ.