The U.S. surgeon general raised a national alarm Thursday about the use of marijuana among pregnant women and youths at a time when 33 states and the District of Columbia have broadly legalized the substance’s use in some form.

Citing greater access and increased potency of what’s available on the market, Jerome M. Adams and Health and Human Services Secretary Alex Azar said the drug “carries more risk than ever” and announced that they would be starting a public awareness campaign on social media about the effect it can have on the developing brain.

The initiative, they said, is funded by President Trump, who donated his full second-quarter presidential salary of $100,000 to the effort. It’s a drop in the bucket compared to his personal fortune but underscores how much of a priority addiction and substance abuse is for the administration, they said.

“We need to be clear: Some states’ laws on marijuana may have changed. But the science has not. And federal law has not,” Azar said.

Azar also put his weight behind efforts to increase marijuana research — which is limited by the fact that there’s only a single institution, a facility at the University of Mississippi, where it can be cultivated for scientific use because of the plant’s status as a Schedule 1 controlled substance under federal law. Azar said that the work should look at both the risks and the potential benefits of marijuana use, and that he had “very constructive” conversations with the Justice Department and the Drug Enforcement Administration about how to do this.

Those talks led the DEA to announce this week that it would begin to process other pending applications.

U.S. health officials said they have been especially alarmed because the potency of tetrahydrocannabinol (THC) in the new professionally grown strains of the marijuana plant is much higher than it was in the past. In 1995, when marijuana was mostly smoked, the amount was about 4 percent, they said. It’s now 12 percent to 25 percent. Marijuana is also now available in even more-concentrated forms — including cookies and oils — where the concentration can be as high as 80 or 90 percent.

“This isn’t your mother’s marijuana,” Adams stated at the news conference announcing the initiative.

Although the officials said they recognize the potential medicinal uses of marijuana’s components — indeed, low doses of the marijuana extract cannabidiol is now being used to treat seizures in some forms of epilepsy — they emphasized that frequent marijuana use during adolescence can affect attention, memory, decision-making and motivation, and that those youth are more likely to miss classes, do poorly in school and drop out.

In pregnant women, marijuana use can affect the developing fetus’s brain and is linked to lower birth weight. Health officials also emphasized that the American College of Obstetricians and Gynecologists discourage the use of marijuana after pregnancy because THC is transmitted in breast milk.

Adams said he has been traveling around the country, and in states such as Colorado and California, where both medical and recreational marijuana use is legal, clinicians, parents and other community members have approached him about the problem. Marijuana is the most widely used illicit drug among youths ages 12 to 17, according to the 2018 National Survey on Drug Use and Health.

“Over and over again, I hear a great and rising concern about the rapid normalization of marijuana use and the impact that false perception of its safety is having on young people and on pregnant women,” Adams said.

The health advisory is only the second one issued by Adams. The first, which came out in December, involved use of another potentially addictive practice by youth: e-cigarettes. Both efforts are part of the Trump administration’s larger war on addiction.

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