Delta 8 weed is gaining in popularity thanks to a legal loophole. It’s also causing concern among health professionals.

Often called “weed light” or “diet weed,” delta-8 THC is Delta-9 THC’s cousin and has been praised for its more moderate effects. But it’s still a chemically similar drug that produces a high and can be extremely dangerous. Delta-8 THC is marketed in drinks, gummies, tinctures, cookies, vapes and blunts that are available across the U.S.

Thanks to a loophole in the 2018 Farm Bill, which opened up hemp farming nationwide, delta-8 THC has exploded in popularity. It’s primarily found in products sold at gas stations, convenience stores, herb shops and even hemp or CBD stores that skirt marijuana laws by labeling their products as hemp-based. That’s despite the fact that the FDA hasn’t approved delta-8 THC, which doesn’t occur naturally in hemp plants in the same quantity as delta-9 THC does.

While the influx of delta-8 products has been a boon for hemp farmers, it’s not good news for consumers or public safety. In fact, it’s prompted outrage from lawmakers and medical professionals who worry that the unregulated process of refining delta-8 THC into a variety of consumer products could result in toxic chemicals making their way into the final product.

In addition to a lack of regulatory oversight, the process delta 8 weed by which these new products are made can leave behind residual solvents that can be toxic if ingested. It’s also impossible to know what a safe serving size of delta-8 THC is, especially if it’s not from a regulated dispensary.

What is known is that delta-8 THC has the same effect on the brain as Delta-9 THC, but it is absorbed much more quickly by the body and reaches the bloodstream faster. In a recent study, researchers found that people who took larger servings of delta-8 THC experienced greater psychoactive effects than those who consumed smaller servings.

It’s also not clear what a safe dose of delta-8 THC is for children and teens, and that isn’t sitting well with some experts. “It is possible to consume too much of any THC isomer, including delta-8,” says Kyle Boyar, a research associate at the University of California San Diego’s Center for Medicinal Cannabis Research. “Adolescents and young adults are particularly susceptible to adverse reactions to delta-8 THC.”

It’s also not clear what the safe level of THC is for pregnant women, breastfeeding mothers or people with serious health problems. That’s a big problem since most of the cases involving delta-8 THC exposures have involved kids and teens, with 40% of those cases resulting in hospitalizations and 72% of those requiring medical evaluation at a health care facility. And those numbers are likely understated.