There’s no proof that CBD stops the spread of cancer in people or cures anxiety in dogs. Nor is there any evidence that the fashionable, nonintoxicating cannabis compound is effective in treating Parkinson’s disease.

But that didn’t stop Curaleaf from making those claims — and dozens of others — on its websites, online stores, and on social media.

Curaleaf, which claims to be the world’s largest cannabis company, has been “illegally” selling unapproved products containing cannabidiol (CBD) with unproven claims that they can treat a panoply of ailments, according to the U.S. Food and Drug Administration. On Tuesday, the FDA fired off a sternly worded letter to the company ordering it to stop.

Curaleaf Holdings (OTC: CURLF) closed Tuesday at $7.40, down 7.27%.

Based in Wakefield, Mass., Curaleaf operates medical marijuana dispensaries and cultivation facilities in 12 states, including New Jersey. With last week’s acquisition of Grassroots, Curaleaf will soon take over Herbology medical marijuana dispensaries in Pennsylvania.

The company does not appear to be making any overt health claims for medical marijuana products containing THC (the compound that’s intoxicating). Individual states prevent medical marijuana companies from making any health claims, and can revoke a company’s license if they step out of line.

“Selling unapproved products with unsubstantiated therapeutic claims ... can put patients and consumers at risk by leading them to put off important medical care,” said acting FDA Commissioner Ned Sharpless. “Additionally, there are many unanswered questions about the science, safety, effectiveness, and quality of unapproved products containing CBD.”

Testing has revealed that some CBD products contain toxic metals, such as lead or other chemical compounds, that can cause allergic reactions or serious illness. The FDA has approved a highly refined form of CBD only to treat rare forms of epilepsy. There is no scientific proof that the substance has an effect on any other ailment. The agency has never approved cannabis or cannabis-derived compounds for any use in pets. Most CBD products are not tested for purity, potency, or quality.

Curaleaf issued a statement hours after the FDA publicized its letter.

“Compliance is a top priority for Curaleaf and the company is fully committed to complying with FDA requirements for all of the products that it markets,” the statement said. “We can affirm that nothing in the letter raises any issues concerning the quality and consistency of any Curaleaf product.”

Failure to correct the violations could result in legal action and the seizure of products, the FDA said. The federal agency previously issued stern warnings to other CBD manufacturers and retailers making similar unsubstantiated health claims.

“This shows the FDA means what they say,” said William Roark, who co-chairs the Pennsylvania Bar Association’s committee on cannabis and hemp. “The line of enforcement is being drawn a little closer to the line of legality. I hope this means they’re cleaning up this ever expanding industry.”

For more news about cannabis and medical marijuana, visit Inquirer.com/cannabis