When they aren’t working or taking care of their autistic children, Melissa Eaton and Amanda Seigler are moles.

Eaton, 39, a single mother from Salisbury, North Carolina, and Seigler, 38, a mom to six in Lake Worth, Florida, have spent much of their free time in the last three years infiltrating more than a dozen private Facebook groups for parents of autistic kids. In some of these groups, members describe using dubious, dangerous methods to try to “heal” their children’s autism — a condition with no medically known cause or cure.

The parents in many of these groups, which have ranged from tens to tens of thousands of members, believe that autism is caused by a hodgepodge of phenomena, including viruses, bacteria, fungal infections, parasites, heavy metal poisoning from vaccines, general inflammation, allergies, gluten and even the moon.

The so-called treatments are equally confused. Some parents credit turpentine or their children’s own urine as the secret miracle drug for reversing autism. One of the most sought-after chemicals is chlorine dioxide — a compound that the Food and Drug Administration warns amounts to industrial bleach, and doctors say can cause permanent harm. Parents still give it to their children orally, through enemas, and in baths. Proponents of chlorine dioxide profit off these parents’ fears and hopes by selling books about the supposed “cure,” marketing the chemicals and posting how-to videos.

Melissa Eaton Courtesy of Melissa Eaton

“It really weighs on you, but kids are being abused,” Eaton said. “You see it. You have the choice of doing something about it or letting it go. And I’m not the kind of person who can see something like that and just forget about it.”

To gain entrance to these groups, Eaton and Seigler disguise themselves as desperate parents looking for answers to their child’s autism. Once they’re in, they take screenshots of posts from parents who describe giving these chemicals to their children, often with disastrous results.

“My son is constantly making a gasping sound,” posted one Kansas mother who claimed to treat her adult son with chlorine dioxide, according to screenshots shared by Eaton and Seigler. “He won’t open his mouth,” a Canadian mom wrote of her 2-year-old’s unwillingness to drink the chlorine dioxide. “He screams. Spits. Flips over.”

Amanda Seigler Courtesy of Amanda Seigler

Horrified by the treatment of these children, Eaton and Seigler research the parents online to determine their identity and location, then send screenshots of the Facebook posts to the local Child Protective Services division, though they rarely hear back on whether action was taken. The pair say they’ve reported over 100 parents since 2016. They also report the posts to Facebook and have submitted their findings to the Food and Drug Administration, the Department of Justice and child abuse organizations.

Recently, the tide has begun to turn in their favor.

Over the past year, amid growing mistrust of big tech — as well as rising concern about anti-vaccine misinformation during a resurgence of measles — lawmakers and health advocates have turned up pressure on Facebook and other companies to stop the viral spread of harmful anti-vaccination propaganda and similar health misinformation on their platforms.

Facebook, YouTube and Amazon all answered with policy changes, removing some fear-mongering content related to vaccines. Those crackdowns also swept up content related to faux autism cures, including chlorine dioxide.

But problems persist. For every book removed from Amazon or private group shuttered on Facebook, others spring up. And proponents of chlorine dioxide are finding new corners of the internet to colonize, where their most loyal followers — parents desperate for a cure for the incurable — will continue to find them.

That means Eaton and Seigler still have plenty of work to do.

“The lack of action by platforms has turned all of us into content moderators,” said Joan Donovan, director of the Technology and Social Change Research Project at Harvard University’s Shorenstein Center.

“We are all growing weary of the platform companies’ inability to squash illicit, illegal and harassing behavior online,” Donovan continued, referring to issues ranging from anti-vaccine misinformation campaigns to mass shootings live-streamed on the platforms. “It goes back to their dogmatic belief in openness as an unmitigated social good. It’s damaging to have health misinformation spread at such a huge scale.”

Inside the investigations

Childhood rates of autism have risen sharply over the last decade, affecting 1 in 59 children in the U.S., according to the Centers for Disease Control and Prevention. Doctors are unable to offer parents a cure, and increasingly, parents turn to social media for answers.

Seigler was searching Facebook for information about her son’s autism diagnosis in 2015 when she learned about the chlorine dioxide groups.

“It went through my mind: What if someone tried to do that to my children?” said Seigler, a veterinary technician and mother to three biological children and adoptive mother to three of her husband’s minor siblings.

Now Seigler — who sees autism as a different way of being, not a disease to be cured — spends at least three days a week scouring Facebook for these posts, trying to stop what she has reported to local authorities as the abuse of autistic children.

“I do it at night,” Seigler said. “I don’t want to expose my children to this world while I’m reporting. After they go to bed, I go online.”

Eaton, whose husband died in 2011, fits in the sleuthing during the day, when her son is at school and she’s not working her loss-prevention job at a burglar alarm company.

The groups are filled with parents who say they have tried treating their children with chlorine dioxide.

“Have not been able to get 5 year old to cooperate with enemas,” a Massachusetts mother complained, according to a screenshot provided by Eaton and Seigler, who work together in their investigating.

One Georgia mother posted a photo of a long thread of what looks like mucus that she said dislodged after giving her autistic son a chlorine dioxide emema. In the caption, she wrote, “It broke in half when Jojo trying to escape.”

NBC News reached out to each of the parents behind the posts but did not receive any responses.

The worst part is the comments, which suggest that the children’s adverse reactions are just proof that the chlorine dioxide is working, Eaton and Seigler said.

Eaton and Seigler often do their work with little sense of whether they’re making a difference. State privacy laws mean they don’t hear back on most of their child abuse reports, and federal agencies have been hesitant to act on their tips, often claiming a lack of jurisdiction or evidence, according to emails viewed by NBC News. The Department of Justice declined to comment, and the FDA did not respond to a request for comment. And for years, until the recent crackdown on health misinformation groups, Eaton said, Facebook simply replied with a “blanket statement that it doesn’t violate their policy.”

It’s not just Facebook. Evangelists for dubious autism cures have long relied on Amazon and eBay to sell their books and chemicals like chlorine dioxide, YouTube to share their how-to videos, and Skype and other social media to spread the word to their millions of followers — adherents who take to all these platforms to profess their devotion.

“It’s like a cult,” Seigler said.

The origins of a dangerous 'cure'

Chlorine dioxide — a hazardous mix of sodium chlorite and an acid activator such as citric acid — was first promoted as a miracle cure two decades ago by Jim Humble, a former Scientologist and gold prospector.

Humble, 86, claimed he’d used the chemical compound to heal a case of malaria while on a South American expedition. It worked so well, Humble says in his book and on his website, that he named himself the archbishop of a new religion devoted to chlorine dioxide, branded it the Miracle Mineral Solution, or MMS for short, and promoted it as a cure for AIDS, cancer, diabetes and virtually every other malady. Humble did not respond to a request for comment.

But it was Kerri Rivera, a former Chicago real estate agent, who brought chlorine dioxide to the autism community and became its best-known proponent.

Kerri Rivera is interviewed by NBC Chicago via Skype at her home in Puerto Vallarta, Mexico, in 2015. NBC Chicago

As she tells it in her 2013 book, “Healing the Symptoms Known as Autism,” Rivera, who is not a doctor, stumbled across Humble’s teachings while experimenting with autism cures on her son. Rivera had made contacts in the autism cure world by trying different en vogue regimens like hyperbaric chambers and heavy metal antidotes.

“Disappointingly, there was absolutely nothing on the Internet about autism and Miracle Mineral Solution (MMS),” Rivera wrote in her book.

Rivera changed that, laying out the particulars of her chlorine dioxide protocol in her book, which she promoted on her website, in Facebook groups and in YouTube videos. Rivera created a line of supplements and built a consultation business through Facebook and Skype to bring the “treatment” to all autistic children, all while traveling the autism cure circuit, where parents attending autism and anti-vaccination conferences received her as a savior. Today, she lives and operates a clinic offering chlorine dioxide regimens in Puerto Vallarta, Mexico, and claims to have cured autism in more than 500 children.

The ingredients that make up Rivera’s chlorine dioxide protocol aren’t illegal — sodium chlorite and acid are used together for purposes outside of human consumption like bleaching paper and for wastewater treatments — so regulation of its sale is nearly impossible. But it is illegal under both federal and state consumer protection laws to market or sell chlorine dioxide as a cure for human ailments. After inquiries from the Illinois attorney general’s office in 2015, Rivera agreed not to conduct seminars or sell products in the state.

"This stuff does nothing other than introduce potential risk." Dr. Daniel Brooks

Rivera declined to be interviewed by NBC News, but in emails she defended chlorine dioxide and her credentials. “This is a medical issue. I have a degree in homeopathy and work with MDs and PhD scientists,” she wrote. Rivera did not respond to requests for more information about these doctors and the institution that granted her degree.

Doctors warn chlorine dioxide could do irreparable harm to a child’s body, by damaging tissues in the digestive system and wreaking havoc on red blood cells.

“It can lead to kidney damage and kidney failure,” said Dr. Daniel Brooks, medical director at Banner University Medical Center’s Poison and Drug Information Center and Outpatient Toxicology Clinic in Phoenix. He called its use to treat autism “ludicrous.”

“This stuff does nothing other than introduce potential risk,” Brooks said.

In a video, Rivera scoffs at doctors’ warnings: “If it’s deadly, we would see dead people.”

In fact, we do. In the last five years, poison control centers have managed 16,521 cases nationwide dealing with chlorine dioxide, according to data provided by the American Association of Poison Control Centers. Approximately 2,500 of those cases involved children under 12; it’s not clear how many of those children were autistic.

The data showed serious side effects from chlorine dioxide poisoning in 2,123 cases since 2014. Fifty of those cases were considered life-threatening, and eight people died.

A review of a separate database, the Food and Drug Administration’s Adverse Event Reporting System, found eight cases of serious injuries from chlorine dioxide since 2004. The cases included a 6-year-old autistic girl hospitalized with liver failure in 2017.

‘She wasn't listening to anybody'

In 2018, Jose Serrano called the Indianapolis police department to complain for the second time in weeks that his wife was making their 2-year-old daughter drink a chlorine dioxide solution in an attempt to cure her autism. Police responded by calling the state’s Child Protective Services division, who removed the child from her mother’s home.

Serrano, 29, who was separated from his wife at the time, told NBC News that she had been secretly dosing their daughter in the bathroom to hide it from him and the rest of her family, who all disapproved.

“She was just frustrated with the autism,” Serrano said.

She learned about the concoction in a Facebook group, according to the police report.

"She wasn't listening to anybody,” Serrano said. “When we found out, we told her, her brothers told her. I don't know if she's still in her delusional world. But she's always looking for the solution."

Serrano currently has custody of his daughter, now 3. It took a few months for a full-body rash, the only side effect he saw from the chlorine dioxide, to go away, he said.

“She has autism. But it is going to get better,” Serrano said. “She's improved a lot. She says some words here and there. But I know it’s going to take a long time."

When reached by phone, Serrano’s ex-wife, who has not been charged with a crime and spoke on the condition that she not be named out of concern for her privacy, said she regretted trying to cure her daughter’s autism with chlorine dioxide. “I love my daughter and having her with me is the most important thing,” she said.

A series of purges

Emma Dalmayne was among the first and remains one of the loudest disability rights advocates to fight against harmful autism “cures.” A London mother to autistic children and autistic herself, Dalmayne has railed against dangerous treatments like chlorine dioxide since 2015. It was Dalmayne who inspired Eaton and Seigler by first infiltrating Rivera’s groups and making videos exposing parents who treated their children with chlorine dioxide.

In 2018, prompted by a series of articles in the British tabloid Daily Mirror that were informed by Dalmayne, Facebook closed several of Rivera’s pages and groups with thousands of followers. But administrators for the banned groups, including Rivera, simply created new private groups, and more carefully vetted would-be members.

“The problem is if you manage to get one knocked down, it reopens the next day but it goes secret,” Dalmayne said. “So unless you've got a good fake profile, which I have, and you're friends with people in these groups who will tell you where the next secret group has opened, you can't report them. A lot of them I'm not in and we’ll never know about.”

A more serious round of purges started in March, when Amazon took the unusual step of banning Rivera’s book and an autism “cure” book by another author. Amazon declined to elaborate on the ban, which came one day after a Wired article criticized Amazon for selling autism cure books. Rivera said in an email to NBC News that the removal of her book would “decrease public awareness” of her message and that Amazon was “responding to media-generated hysteria.”

Days later, YouTube began deleting dozens of Rivera’s videos and channels, which featured interviews with parents and explainers for mixing and administering chlorine dioxide. A representative for Google, which owns YouTube, said the chlorine dioxide content, which also included a channel not run by Rivera, had been removed because it violated standards against “content intended to encourage dangerous activities that have an inherent risk of physical harm.”

Yahoo followed in April, canceling Rivera’s longtime email account. Eaton had emailed and called the company’s press, legal and law enforcement departments to inform them that Rivera was using the account for her chlorine dioxide business. Yahoo did not respond to a request for comment.

The biggest blow came in April, when Facebook deleted Rivera’s public profile, a page for her books with over 3,600 followers and a secret group with about 550 members. “Facebook wants to destroy our autism self-help community,” Rivera wrote in a newsletter to her followers after the crackdown. “Now 31,000 families that came to this page for advice, questions and solace have in essence been kicked off Facebook.”

A Facebook spokesperson said in a statement to NBC News that Rivera’s groups were removed for violating Facebook’s rules on “nonmedical drugs,” which forbid content that promotes drug sales or describes personal drug use outside of recovery.

“We believe in giving people a voice, but we also want everyone using Facebook to feel safe,” the company spokesperson said in a statement to NBC News.

An uphill fight

Because of Facebook and YouTube’s whack-a-mole style of enforcement, in which users are rarely banned even if their groups are closed, Rivera’s content is still easy to find on the platforms. Rivera still has a personal Facebook account, a professional page and other groups dedicated to a separate diet brand, which she uses to sell supplements and promote her autism cure website. Rivera also still has a YouTube account and numerous conspiracy channels have featured interviews with her in the last month.

Rivera tried to move her chlorine dioxide groups from Facebook to MeWe, a less user-friendly group chat service billed by fringe groups and some conservatives as the answer to censorship from tech companies. But the 100 or so members of Rivera’s MeWe group miss the community they made on Facebook, which had five times as many members.

When a MeWe moderator asked what Rivera thought of the new setup, Rivera replied, “Insane.”

Meanwhile, Eaton and Seigler are watching MeWe, as well as Rivera’s Facebook pages, for signs of new groups targeting parents of autistic kids.

“Her profile needs to go and they need to ban her IP address,” Eaton said, adding that Rivera’s remaining accounts have allowed her to warn followers about upcoming bans and tell them how to skirt them.

“I’m also trying to work and take care of my family,” Eaton said. “It shouldn’t be on the public to try and handle this.”