(ABC NEWS) — A supposed “miracle cure” for autism is really a kind of industrial bleach, federal prosecutors say, but that hasn’t stopped people claiming to be archbishops of a church from urging desperate parents to use it on their autistic children.

“This is a poison. This is a high-strength industrial bleach,” said Dr. Paul Wang, senior vice president of Autism Speaks.

Yet, under the guise of the Genesis II Church of Health and Healing, it’s estimated that the “miracle cure” has attracted thousands of desperate American parents who have given it to their autistic children.

“It really scares me that people would give this to their kids because it is a poison,” said Wang, in an interview to be broadcast Friday on ABC News’ “20/20.”

The church leaders say people who take the “cure” should not worry if they suffer side effects of bouts of diarrhea and nausea. They say it is a sign it’s working and that a few drops will not cause any harm.

Wang said it is no different that torturing autistic children.

“A lot of kids with autism do not have good communication skills,” he said. “So they can’t say that it’s hurting them.”

Like many parents of autistic children, Roland Eggers looked into the claims being made for the “miracle cure.”

“You thrive on this illusion that you’re going to somehow fix your kid or that one day you’re gonna unautismize your child,” he told ABC News.

But after checking online, Eggers quickly concluded he would not use it for his 12-year-old son Mitchell.

“They’ve got their own Facebook group. There are people admitting to using this stuff on their children. Children are experiencing symptoms,” Eggers said he found. “You are doing it at the expense of these defenseless children. How, how, how can you not call that evil?”

The man who says he discovered the miracle cure and founded the Genesis II church is a one-time gold prospector from Nevada, Jim Humble, who calls himself an archbishop and claims he came to Earth from another galaxy.

But as wacky as he may sound, it appears that Archbishop Humble and other church leaders have prospered, using slick internet videos promoting the “miracle cure” called MMS, and calling it a church sacrament available for anyone offering “donations.” One website offered five sets of chemicals to make MMS for “donations” of $95.99.

Tests conducted for ABC News show the “miracle cure” is little more than a chemical that when mixed with citric acid produces chlorine dioxide.

Federal prosecutors said it would be useful to clean swimming pools or kitchen countertops, but does not cure autism or anything else.

“They might as well be selling Clorox,” said Ben Mizer of the U.S. Department of Justice, who has overseen the prosecution of at least one person selling the “miracle cure.”

“You wouldn’t drink Clorox so there is no reason you should drink MMS,” he said.

And, Mizer said, Humble and others are wrong if they think forming a church protects them from possible prosecution.

“They can be prosecuted, yes, if they are selling it in order to cure diseases and are telling people that it will cure diseases,” Mizer said.

Now under scrutiny by U.S. authorities, Humble has lived in Mexico for the last few years, where ABC News tracked him down earlier this month.

He reaffirmed his advice that autistic children should be treated with a few drops of the MMS cure.

“I do, yes,” he said.

And when asked if he was a con man, Humble said, “It’s ain’t true.”

Dr. Wang of Autism Speaks said Humble and his followers are taking advantage of vulnerable parents.

“Unfortunately, there’s no cure. There are a lot of things that can help kids with autism and adults with autism, too, but there’s not cure for it,” Wang said. “You can’t blame any parent for wanting to help their child. In this case, we just want to make sure everybody understands MMS is not a cure.”