Parents are poisoning their autistic children with bleach. The alarming trend is promoted online as a 'miracle cure.'

Some parents are poisoning their children with chlorine dioxide to heal autism, according to an NBC News investigation.

The alarming so-called treatment is being promoted online by proponents who claim it's a "miracle cure."

Chlorine dioxide can cause irreparable bodily harm, doctors warn. It damages the digestive system and wreaks havoc on red blood cells.

"It can lead to kidney damage and kidney failure," Dr. Daniel Brooks, medical director at Banner University Medical Center's Poison and Drug Information Center and Outpatient Toxicology Clinic in Phoenix, told NBC News.

Brooks described the use of the chemical as a treatment for autism as "ludicrous."

Still, desperate parents have joined private Facebook groups where members post about their desperate and dangerous attempts to cure their autistic children. Some groups have tens of thousands of members with parents who believe their child's disorder was caused by anything from viruses to parasites to vaccines to the moon.

Chlorine dioxide is used for water purification. The U.S. Environmental Protection Agency has set a maximum level of 0.8 mg/L in drinking water.

The so-called autism treatment calls for unsafe levels to be administered to children up to eight times a day.

Where did this dangerous idea come from?

Jim Humble, a former Scientologist and gold prospector, was the first to claim chlorine dioxide had healing properties for AIDS, cancer, autism and nearly every other ailment. He has promoted the idea on his website, in his book, "MMS Health Recovery Guidebook, "and even created a new religion dedicated to the concoction that he branded Miracle Mineral Solution."

Kerri Rivera, a former Chicago real estate agent, jumped on the chlorine dioxide train and now is among the loudest proponents for a fake cure.

Rivera, who now lives in Mexico, promotes the treatment online and discussed it in her 2013 book, "Healing the Symptoms Known as Autism."

She runs a clinic in Puerto Vallarta where she claims she has cured more than 500 cases of autism. Rivera is not a physician.

"This is a medical issue. I have a degree in homeopathy and work with MDs and PhD scientists," Rivera told NBC.

In an email to NBC News, Rivera did not respond to requests for information about her degree or the doctors she allegedly works with at the clinic.

How prevalent is autism and what should parents do?

About one in 59 children in the U.S. is diagnosed with an autism spectrum disorder, according to the Centers for Disease Control and Prevention. The disorder's prevalence has risen sharply over the last two decades. In 2000, only about 1 in 150 children were identified with autism.

"Although there is no available medication that can cure ASDs, some medications may relieve various behavioral and physiological symptoms associated with the disorders," according to the CDC website.

Parents should seek help for their children from a physician and other health care professionals.

What else?

Several social media platforms have begun removing pages that spread misinformation.

Last month, Facebook shut down Rivera's page and group called "Healing the Symptoms Known as Autism," but she still has multiple accounts that are still active including Keto Kerri, Kerri Rivera Profile and I am Keto Kerri, Patheos reported.

YouTube has reportedly deleted dozens of Rivera's videos and Amazon has banned her book.