The United States surgeon general issued an advisory on Thursday to warn pregnant people and teens about the risks of cannabis use. In the notice, Surgeon General Dr. Jerome Adams warns that the THC potency of marijuana has increased over the years, especially with the advent of powerful cannabis concentrates.

“The scary truth is that the actual potential for harm has increased,” Adams said at a press conference with health officials from the Trump administration on Thursday. “This ain’t your mother’s marijuana.”

Adams said that the potency of cannabis available in the United States has increased from about 4 percent THC 20 years ago to levels of 12 percent to 25 percent THC today. Cannabis concentrates can contain more than 75 percent THC, according to the advisory. Cannabis, he said, is the most commonly used illicit drug in the United States.

Dangers Of Cannabis Use By Teens

Adams said that with the legalization of cannabis in one form or another in 33 states, the perceived level of risk posed by marijuana use, especially by young people, has gone down. Research has shown, however, that there could be some negative health effects from cannabis use by adolescents.

Young people who regularly use marijuana are “more likely to show a decline in IQ and school performance [and] are more apt to miss classes,” Adams told NPR.

The surgeon general also noted that cannabis use by young people poses a risk of addiction.

“Nearly 1 in 5 people who begin marijuana use during adolescence become addicted,” Adams said. “That’s scary to me as the dad of a 15-, a 13- and a 9-year-old.”

Dr. Elinore F. McCance-Katz, assistant secretary for mental health and substance use for the Department of Health and Human Services, said that a potential connection between cannabis use and an increased rate of major depression in adolescents is a cause for concern.

“While we cannot say that marijuana is causal of those things, when you look at the increased trend, it is quite concerning,” said McCance-Katz.

Use During Pregnancy May Also Be Risky

Adams also warned about the potential dangers of cannabis use during pregnancy, which include low birth weight, an increased chance of preterm birth, and developmental disabilities in children. Between 2002 and 2017 in a national survey, the use of marijuana in the past month by pregnant people doubled from 3.4 percent to 7 percent.

And in a survey by a large national health system, cannabis use by pregnant people rose from 4.2 percent to 7.1 percent between 2009 and 2016, an increase of 69 percent. Some cannabis dispensaries, he said, are even recommending cannabis as a treatment for morning sickness.

Dr. Lauren M. Jansson, the pediatric director of the Center for Addiction and Pregnancy at Johns Hopkins Bayview Medical Center in Baltimore, agreed with Adams on the dangers of cannabis use during pregnancy or breastfeeding.

“He’s 100 percent correct,” she said. “No amount of marijuana is safe for pregnant or lactating women. Disturbingly, more and more women are using it.”

Alex M. Azar II, the secretary of health and human services, said that teens and pregnant people should avoid all cannabis use.

“This is a dangerous drug,” Mr. Azar said. “No amount of marijuana use during pregnancy or adolescence is safe.”

Azar added that President Trump was donating $100,000, a quarter of his salary, to fund a digital media campaign highlighting the dangers of marijuana use.

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