"Not every health agency in the world and not every spokesperson in the world has agreed that glyphosate can cause cancer", said Olga Naidenko, the Environmental Working Group's senior science adviser for children's health.
Some popular breakfast foods and cereals marketed to children contain a weed-killing chemical that some health authorities have linked to cancer.
The report looked at granola, instant oats, oat breakfast cereals, snack bars and whole oats products.
Feature Image: Glyphosate, the primary ingredient in the weed killer Roundup and one of the most widely used herbicides in agriculture. In 2015, the EPA said that glyphosate has a low toxicity for people but could cause problems for some pets if they consume the chemical.
EWG is urging the EPA to review the evidence linking glyphosate to increased cancer risk and other deleterious health effects - the organization also says that the EPA should limit things like the practice of applying the chemical just before harvesting. Still, there is much debate on whether glyphosate is actually unsafe, with some findings suggesting that it is only harmful to humans in high doses.
The report comes days after Monsanto was ordered to award $289 million to a terminally ill man who claimed that excessive exposure and use of Roundup caused his non-Hodgkin's lymphoma. There is also a plan to intimate and petition the EPA (United States Environmental Protection Agency) to stop using glyphosate. Their daily glyphosate intake is estimated at 230 times the 160ppb benchmark, according to EWG. According to the U.S. Geological Survey, more than 200 million pounds of glyphosate are sprayed on crops each year.
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Both Quaker Oats and General Mills, which makes Cheerios, said that their products were safe and met federal standards.
The Washington, D.C. -based EWG, a research and advocacy group, says it found the highest levels of glyphosate in two samples of Quaker Old Fashioned Oats.
"It is very troubling that cereals children like to eat contain glyphosate", said Alexis Temkin, an EWG toxicologist and author of the report. But for the average person who uses it occasionally for yard work, are Roundup and other weed killers still safe to use?
"Glyphosate does not belong in cereal", Tenkin wrote.
General Mills says its products are safe and meet safety regulations.
In a statement, Quaker told CBS News: "We proudly stand by the safety and quality of our Quaker products".
But Cook said that General Mills and Quaker Oats are "relying on outdated safety standards". It's not exactly clear how risky the chemical is for humans. It added that the reported levels of the chemical "are significantly below any regulatory limits" and compliance standards for human consumption.
"This is what the poison control centers are here for, if there's ever any question of exposure or concern, we're a great free, public health entity", he says.