NASHVILLE, Tenn. (WTVF) — With thousands of acres near harvest in Tennessee, one TSU researcher is worried about how some processors extract hemp oil.

Dr. Roy Bullock is the Director of the hemp program at TSU. He knows there are many processors in the state, but isn't sure about what methods everyone is using.

"Right now, with everybody in the hemp program, nobody is exactly sure about any processes that [are] going on," said Dr. Bullock. "We don't know exactly what they're doing from a university standpoint."

Hemp can be extracted in a number of ways. Dr. Bullock said, in his opinion, the way that shows the most promise is by using liquid frozen carbon dioxide.

"Once that extracts the oil, it evaporates off and leaves no residue. Almost like dry ice, once it melts it just disappears," he said. What Bullock is concerned about are other methods that could leave chemical residue in the oil.

"I'm concerned that folks with use materials like Methanol," he said. "Methanol is known if you have residue in your food, if you take it internally it can effect your eyesight. That's one material I know that people have tried. I don't know if it's being used still."

Without close oversight over those who process oil, it's possible oil with some type of chemical residue could make it to store shelves.

But, it's more likely that some products are misrepresented in stores without proper testing.

"The concentration in the CBD in some of these oils can vary," said Bullock. "Anyone can put a number on the bottle. Has that been verified?"

Bullock said he hopes to begin processing his own hemp oil on the TSU campus to conduct research on the process. It will cost $500,000 to get started.

Right now in the state there's a shortage of processors. Farmers report buyers are scarce or backing out of contracts for acres of crop that could be worth $40,000.