Iryna Imago via Getty Images Kratom powder and capsules are seen on a table. Ohio is seeking to ban the popular herbal supplement based on a series of disputed claims.

The Ohio Board of Pharmacy voted earlier this month to classify the popular herbal supplement kratom as a Schedule I controlled substance alongside drugs like heroin and other more deadly synthetic opioids.

To justify the decision, officials have pointed to reports claiming many users in the state are now injecting kratom, a botanical substance that they allege has also killed a number of people in Ohio in recent years.

Scientists and kratom advocates are now challenging those claims, calling them misleading and even nonsensical.

Kratom is an herbal drug derived from the dried leaves of a Southeast Asian tree in the coffee family. Six states and a number of cities have already banned kratom, citing concerns over the opioid-like effects associated with its two primary active alkaloids, mitragynine and 7-hydroxymitragynine. Opponents say the activity of those compounds makes kratom a threat to public safety. But supporters say it could make kratom a powerful weapon against the opioid crisis as an alternative to certain prescription drugs and a replacement or step-down treatment for more dangerous opioids.

The Board of Pharmacy’s justification for scheduling kratom appears to mirror the warnings the U.S. Food and Drug Administration has issued over the past year as it portrays kratom as having a “high potential for abuse,” “no accepted medical use,” and lacking “accepted safety for use in treatment under medical supervision.”

Although federal authorities are still considering a federal ban on kratom, they haven’t yet announced how they’ll proceed.

In a document explaining the proposed rescheduling, the Ohio Board of Pharmacy points to six deaths in Ohio between 2016 and 2017 in which “kratom was indicated as the primary cause of death.” It also refers to an Ohio law enforcement report stating that “the most common route of administration for kratom is intravenous injection,” and that heroin dealers in the state are selling kratom along with illicit substances.

Details about the six deaths provided to HuffPost by the Ohio Department of Health suggest that none was conclusively caused by mitragynine alone. Four of the deaths appear to be the result of drug overdoses involving multiple substances. Fentanyl or other potent opioid analogs were present in three cases, while the other showed a positive screen for multiple prescription and over-the-counter drugs. One person died of flu and pneumonia, though “mitragynine toxicity” was also determined to be a cause of death, a Department of Health official told HuffPost. Another individual was found to have died of a “cardiac rhythm,” which was attributed to the consumption of kratom tea.

In an email to HuffPost, a spokesperson for the Ohio Board of Pharmacy would not say if the agency maintained that kratom was the “primary cause of death” in those cases. The spokesperson did say that the deaths are just one of the factors the board considered while weighing a ban.

But advocates with the American Kratom Association have taken issue with the rest of the board’s criteria as well. The organization says it plans to file a petition requesting the board rescind its scheduling proposal because it directly conflicts with a previously published study finding kratom has a “favorable safety profile” and low abuse potential.