The Colorado Board of Health announced it will fund grants totaling more than $8 million for studies examining the potential medical benefits of marijuana. The studies will examine marijuana’s effects on epilepsy, pain relief, brain tumors and post-traumatic stress disorder (PTSD).

Three of the eight studies need federal approval, according to the Associated Press. They will also need access to the nation’s only legal source of marijuana for research, the Marijuana Research Project at the University of Mississippi. The other five studies will be observational, meaning the participants will be providing their own marijuana.

While 23 states and the District of Columbia allow marijuana use by people with various medical conditions, the drug remains illegal under federal law.

“This is the first time we’ve had government money to look at the efficacy of marijuana, not the harms of marijuana,” said Dr. Suzanne Sisley, an Arizona psychiatrist who will help run a study on marijuana for veterans with PTSD.

According to Colorado Chief Medical Officer Dr. Larry Wolk, research is needed to determine how marijuana may help patients, and at what dose. “There’s nowhere else in medicine where we give a patient some seeds and say, ‘Go grow this and process it and then figure out how much you need,’” he told the AP. “We need research dollars so we can answer more questions.”

The research approved this week includes studies on using marijuana to treat PTSD; whether marijuana can benefit teens and young adults with irritable bowel syndrome; marijuana’s ability to relieve pain in children with brain tumors; how an oil derived from marijuana plants affects children with epilepsy; and comparing marijuana and oxycodone for pain relief.