The recent advent of so-called “synthetic pot” is a rising public health concern, researchers warn, sending kids to the emergency room and prompting parental calls to poison control centers.

The concoction was originally conceived in a laboratory setting as a research aid for animal studies involving THC, a key stimulative ingredient in marijuana, the new report noted.

But purely recreational street use of this widely varying mix of plants and herbal ingredients is growing. It’s widely available and is currently undetectable by commercial drug tests.

“The concern is that we’re going to really see this grow in popularity,” said study author Dr. Joanna Cohen, an assistant professor of pediatrics and emergency medicine at Children’s National Medical Center, in Washington, D.C. “Because it’s really easy to get, and because kids know that it doesn’t come back on typical clinically useful urine drug screenings that we would use in an ER.”

According to the American Association of Poison Control Centers, roughly 4,500 calls have come in since 2010 regarding toxicity stemming from synthetic marijuana use.

The new study appears online March 19 and in the April issue of Pediatrics.

Commonly referred to by a host of street names — such as “K2,” “Spice” and “Aroma” — synthetic pot isn’t made according to a fixed recipe and can differ from lab to lab and batch to batch.

The resulting product often includes some combination of blue and pink lotus, red clover, honey, vanilla, bay bean and marshmallow.

The blend — which can be ingested either orally or via smoke inhalation — is sprayed with chemicals that render the composition toxic.

Until recently, these synthetic mixtures were legal to purchase and readily available in corner stores and gas stations throughout the United States and on the Internet. In February, the U.S. Drug Enforcement Agency classified synthetic marijuana as a controlled substance.

That, Cohen cautioned, has done little to slow its popularity.

And because of it’s strong impact on cannabinoid brain receptors, as little as 1 milligram of synthetic marijuana can be intoxicating, the study said. The impact can be stronger than that with naturally grown marijuana, sometimes prompting bouts of paranoia, anxiety, agitation, high blood pressure, profuse sweating, palpitations, irritability, muscle rigidity and, at times, convulsions.

The researchers noted that when users seek medical attention, the varied composition of synthetic pot can make it hard to quickly pinpoint the most dangerous ingredient.

Individual symptoms are usually short-lived, the researchers said, and treatment is available to help control some of the reactions.

In their report, Cohen and her team describe three case examples of teenaged patients who were hospitalized after using the drug, one girl and two boys.

Overall, the patients demonstrated varying degrees of catatonia, an inability to respond to verbal or physical stimulation — including pain — an elevated heart rate, agitation and anxiety, dizziness, headaches, excessive sweating, slowed speech, and confusion.

Two of the patients recovered normal function in three to four hours, while the third patient was kept in hospital overnight before being released.

“What’s important with this is that parents and schools are aware that this is out there,” Cohen said. “And that they look for signs and symptoms of use. If you see a teen who’s agitated, sweating a lot, or acting abnormally in some way it could, of course, be a sign of a serious medical problem, or it could be a sign of drug toxicity. Either way you need to seek medical attention right away.”

“The long-term the goal should be to prevent repeat use,” she added, “because these kids are kids. They’re teenagers and their brains are still developing. So there can be long-term effects, like psychosis and memory loss, from the use of something like synthetic marijuana.”

Steven Shoptaw, a clinical psychologist and a professor in the department of family medicine at the University of California, Los Angeles, suggested that while current concerns surrounding synthetic pot use have some merit, they are dwarfed by the enormous popularity of real marijuana among teens.

“Because [synthetic marijuana] is a relatively new drug, the surveys that measure and monitor drug use in children over time haven’t had a chance to look at this yet, so we don’t know how big a problem this is across the country,” he said.

“But what we do know is that the prevalence of marijuana use among eighth, ninth and tenth graders is very, very high,” Shoptaw said. “And I would say that that’s a much greater problem than ‘Spice’ use. Marijuana is actually way more available to teens, and it is very rich in potent THC. And that, as the authors point out, can pose a lot of problems for developing brains.”

More information

For more on marijuana, synthetic and “natural,” visit the U.S. National Library of Medicine.

SOURCES: Joanna Cohen, M.D., assistant professor, pediatrics and emergency medicine, division of pediatric emergency medicine, Children’s National Medical Center, Washington, D.C.; Steven Shoptaw, Ph.D., clinical psychologist and professor, department of family medicine, University of California, Los Angeles; April 2012 Pediatrics

Last Updated: March 19, 2012