Federal environmental officials scrubbed their website of a report supporting the safety of a common pesticide while a California congressman attempted to arrange an agency meeting with scientists and activists who have spread conspiracy theories about pesticides, vaccines, and breast milk.

The Environmental Protection Agency report officially designated the chemical glyphosate, the key ingredient in popular weed-killing product Roundup, manufactured by agricultural giant Monsanto, "Not likely to be carcinogenic to humans."

The agency said the report—marked "final" and signed by all 13 members of EPA’s Cancer Assessment Review Committee—was published "inadvertently" and that it was conducting additional testing.

Two congressional committees are now investigating the matter.

"The EPA’s backtracking on the finality of its own science review committee’s report raises concerns about the agency’s willingness to provide a fair assessment on this matter," Rep. Lamar Smith (R., Tex.), who chairs the House science committee, wrote in a May letter to EPA chief Gina McCarthy.

The report appeared on EPA’s website on April 29. Three days later, it was removed. Around that time, Rep. Ted Lieu (D., Calif.) was trying to arrange a meeting between top EPA officials and a group of "independent scientists" who blame glyphosate for "a large variety of cancers, organ failures, neurological, [and] environmental harm."

Such warnings are at odds with previous EPA findings, as well as findings by public health officials in Canada, Germany, and Australia.

Lieu asked McCarthy in a December letter to arrange a meeting between EPA scientists and his delegation in "March or April." It will finally happen next week, before the agency formalizes its glyphosate findings.

There are ten members in Lieu’s delegation, and they include a core group of environmental and public health activists whose studies on glyphosate have been widely criticized and debunked.

The "independent scientists" will attend a public congressional briefing on Tuesday morning "about the harmful effects of glyphosate and the necessary action needed to protect the public, animals, and the environment," according to an online invitation.

After the public event, congressional and EPA staff will meet behind closed doors, according to Dr. Stephen Frantz, a leader of the delegation whom Lieu singled out for praise in his December letter to McCarthy.

Sterling Hill, another scheduled attendee, says she has already received media attention for the event.

"The associated press will be there," she wrote on Facebook last month. "Bloomberg news personally called me today. We will be getting national and international attention at this meeting."

Hill is the chief executive of pseudoscientific advocacy group MTHFR Support, which advocates the treatment of illnesses using epigenetics, a field commonly associated with medically dubious and unscientific treatments.

A proponent of "natural" medicine, Hill claims that the federal government is actively suppressing cures for the world’s deadliest illnesses.

"Right now (hate me if you will because the truth hurts) there are cures for things like cancer, MS, crohn's, fatty liver disease, autism, etc.," she wrote last month.

Those cures, Hill wrote, "are being suppressed because of FDA regulations ‘nothing natural can cure treat or prevent disease’ and by pharmaceutical lobbyists that do not have your best interest at heart but your dollar."

Frantz and Hill are members of a research team that also includes MIT computer scientist Stephanie Seneff and Anthony Samsell, who describes himself as an "independent scientist and consultant."

Samsell and Seneff, both of whom will attend next week’s event, co-authored a 2013 study that forms the basis for much of the glyphosate criticism among Lieu’s delegation of "independent scientists."

The study, which linked glyphosate to "gastrointestinal disorders, obesity, diabetes, heart disease, depression, autism, infertility, cancer and Alzheimer’s disease," was criticized for concocting non-existent scientific terminology and failing to conduct any independent empirical observations.

In addition to her work on glyphosate, Seneff is a frequent critic of vaccines, which she claims can cause autism. "I confirmed … that MMR is associated with autism," she said in an interview last year discussing her 2012 study on the measles, mumps, and rubella vaccine.

In the same interview, Seneff praised the work of Andrew Wakefield, the disgraced British academic who in the late 1990s brought theories linking vaccines and autism into the mainstream. "Andrew Wakefield connected [the MMR vaccine] to autism … which was very interesting," Seneff recalled.

The link between autism and the MMR vaccine has been thoroughly debunked.

Another attendee of Lieu’s briefing, Zen Honeycutt, founder of the group Moms Across America, has also blamed vaccines for autism and cited the link as evidence of the dangers of glyphosate.

"Glyphosate breaks down the blood brain barrier, allowing toxins into the brain … toxins like those found in our environment and vaccines," Honeycutt wrote in 2013.

"I am not a doctor but I have Mom common sense," Honeycutt added. "Feeding our kids toxin pesticides and injecting our kids with toxic vaccines, especially while their immune systems are repeatedly being attacked by GMO's and pesticides/herbicides is just risky."

Moms Across America says it is an IRS-registered nonprofit focused on educating parents about the dangers of genetically modified food.

The IRS online database of tax exempt organizations has no record of any current or former nonprofit group by that name, or any group using the tax identification number listed on MAA’s website.

The IRS did not respond to inquiries about Moms Across America’s tax-exempt status. The group and its public relations agent also did not respond to requests for comment.

Moms Across America’s work on glyphosate has drawn fire from experts who say it lacks scientific rigor and irresponsibly spreads concerns about the chemical despite a lack of evidence.

When a Moms Across America study was used to support GMO food labeling legislation in Connecticut, Dr. Ronald Kleinman, the chief physician at the MassGeneral Hospital for Children, wrote a long letter to legislators debunking its sensational claims about glyphosate and GMOs more generally.

Kleinman specifically referenced a Moms Across America study co-authored by Honeycutt on the prevalence of glyphosate in breast milk. "There is no significant risk to infant health from glyphosate based on current use levels," he concluded.

The Moms Across America study was more thoroughly debunked by James Bus, a toxicology expert at engineering and scientific consulting firm Exponent, in a study published in the journal of Regulatory Toxicology and Pharmacology.

"The non-peer-reviewed biomonitoring report published online by Moms Across America … does not support the conclusion that glyphosate concentrations detected in a limited number of urine samples from women, men and children, or breast milk from nursing mothers, pose a health risk to the public, including nursing children," Bus wrote.

Lieu is relying on Honeycutt and other empirically questionable scientists to brief the EPA even as he criticizes major oil companies for misrepresenting scientific facts about climate change. The congressman has been a leading proponent of federal racketeering charges for oil giant Exxon Mobil.

His glyphosate crusade has targeted another corporate giant: Roundup manufacturer Monsanto. In his letter to McCarthy, he suggested that prior EPA determinations about the safety of glyphosate were written at the company’s behest.

Lieu’s office did not respond to questions about his glyphosate position or those of his delegation of "independent scientists."