(Reuters) — The U.S. Food and Drug Administration (FDA) is planning to make recommendations on how to regulate the use of popular cannabis compound CBD in food and supplements, the Wall Street Journal reported on Tuesday, citing agency officials.

After weighing the evidence on the compound’s safety, the FDA will decide within months how to regulate legal cannabis and whether that will require new agency rules or new legislation from Congress, according to the report.

Shares of U.S.-listed cannabis companies were down between 5% and 9% in afternoon trade, following the report.

Cannabidiol, or CBD, is a non-psychoactive compound derived from cannabis.

Cannabis products, excluding Jazz Pharmaceuticals Plc’s Epidiolex, are illegal at the federal level in the United States, although some states allow their use.

The agency wants to know if CBD can be safely eaten every day for a long period or during pregnancy amid concerns about future fertility, Patrick Cournoyer, who heads the FDA office developing the agency’s cannabis strategy, told WSJ.