In the last six years, a "green wave" has been sweeping across the nation as states throughout the country continue to loosen the rules surrounding marijuana. In an era where consumers in California can pick up half an ounce of marijuana on their way home from work as easily as a six pack of beer, scientists are still locked out from researching a drug that is becoming more widely available to the public each year.

Despite medical marijuana being legal in 33 states (recreational marijuana is legal in 10), the federal government still classifies the plant as a Schedule I narcotic — the same classification given to cocaine and heroin — making research on its active ingredient incredibly difficult. Right now, only one facility located in Mississippi is approved by the federal government to grow their own marijuana for research, and many researchers have complained the facility’s product is inadequate when compared to the more potent products being sold at medical and recreational dispensaries. This has resulted in a growing concern within the scientific community that as marijuana becomes more readily available, there will not be a sufficient body of research to help consumers truly understand the health impacts of regular marijuana usage.

“Marijuana is poorly understood,” said Art Caplan, medical ethicist and director of the division of medical ethics at New York University’s Langone Medical Center, on Boston Public Radio. “What’s the active ingredient? How much should you use? How often should you smoke it if you have different kinds of pain? It’s all kind of mysterious because we haven’t done any research.”

The debate about the health benefits and detriments of marijuana has been critical to the divide between pro-legalization advocates and their opponents. Advocates claim the drug can help treat anxiety and depression along with easing chronic pain, while others say long-term usage may lead to psychosis, addiction, and is a gateway drug to heavier substances like opioids and heroin. According to the National Academy of Medicine, who released one of the most comprehensive studies to date on the health impacts of marijuana, the reality is there simply isn’t enough substantive research to reach any qualitative conclusions. In the report, the group concluded that marijuana is effective in reducing pain, but when it came to its role in promoting heart disease, diabetes and its influence on the immune system, the research is too insufficient to draw a conclusion.

Unfortunately for the scientific community, the Trump administration has shown little interest in making it easier to study marijuana. Despite the president’s vague stance, his Health and Human Services Secretary Alex Azar told reporters in Ohio last March that he believed “there is no such thing as medical marijuana. There is no FDA-approved use of marijuana, a botanical plant. I want to be very clear about that,” leaving little room for hope for marijuana advocates and researchers in the United States.

“I don’t think we’re going to see a shift under the Trump administration,” Caplan said. “They seem to have a kind of 1980s drug policy attitude where the way to handle this is prison sentences, border walls and all this kind of stuff.”

As more states push forward with legalizing marijuana in one form or another, it’s not inconceivable that almost all 50 states will eventually allow marijuana to be distributed medically or recreationally. Without federal approval for research, however, some observers worry that consumers will be left in the dark when it comes to making informed decisions about consumption. Right now, the most consensus researchers have on the long-term health impact of marijuana is that they simply don’t know.

“It’s almost a catch-22,” neurologist Staci Gruber told Politico in a Dec. 25 article. “These products are widely available to the public. But as clinical researchers, we can’t administer one drop in a clinical trial.”