An affidavit in the case filed by a special agent with the FDA Office of Criminal Investigations noted: “FDA has received numerous reports of adverse reactions to MMS. These adverse reactions include hospitalizations, life-threatening conditions, and death.”

Grenon, who is now out of prison, told ProPublica that he too is writing a book about chlorine dioxide. “My book will tell the truth.” He declined further comment.

Chlorine dioxide is currently used in many ways that are not harmful. It is found in some consumer products like mouthwashes, but it is not meant to be swallowed in those instances. (One popular mouthwash warns to “keep out of reach of children.”) It’s also available to consumers in do-it-yourself packages where they combine drops from two bottles of different compounds—commonly sodium chlorite and hydrochloric acid—and add it to water. Hikers often carry the drops, or tablets, using small amounts to make quarts of fresh water potable.

But numerous online shoppers post product reviews that go further, referring to it as a tonic. Various online guides, some aimed at parents of autistic children, recommend a shot-glass-size dose, sometimes given multiple times a day and even hourly. That can far exceed the threshold the EPA considers safe.

McCarthy, addressing ProPublica on Substack, wrote: “You point to various online guides that offer what could be considered dangerous dosing instructions. We agree, the internet is a terrifying wasteland of misinformation and disinformation.”

In the Substack video, Kory said he felt compelled to spread the word about chlorine dioxide much as he did about ivermectin, even though it cost him professionally.

He no longer has a valid medical license in Wisconsin or California, where he did not renew them, according to the Substack post. His medical licenses in New York and Michigan are active.

“I like to say I was excommunicated from the church of the medical establishment,” he said in the Substack video. As a result, he said, he turned to telehealth and started a practice.

In the November 6 HighWire episode hosted by Bigtree, the discussion included talk not just of chlorine dioxide’s medicinal potential but also of how cheap and easy it is to obtain.

“On Amazon, it’s literally, you get two bottles, well, it comes in two,” Kory started to explain, before stopping that train of thought.

“I wouldn’t know how to make it,” he said.

This story was originally published by ProPublica. ProPublica is a Pulitzer Prize-winning investigative newsroom. Sign up for The Big Story newsletter to receive stories like this one in your inbox.