From beer to wine to breakfast food, the pesticide glyphosate is showing up in a lot of places that consumers don’t expect to find it. The chemical, a key ingredient in Monsanto’s Roundup weed killer, was declared a “probable carcinogen” by the World Health Organization’s International Agency for Research on Cancer last year. Since then, a number of food and environmental activist groups have started testing for it in an array of products and finding it—albeit in small amounts—almost everywhere. Now a group of consumers are suing Quaker Oats, which is owned by PepsiCo, over the glyphosate that testing paid for by the plaintiffs found in the company’s Quick 1-Minute oats product.

“There is nothing unlawful about Quaker Oats’ growing and processing methods,” according to the suit, which was filed in Federal District Court in New York and California on Monday. “What is unlawful is Quaker’s claim that Quaker Oats is something that it is not in order to capitalize on growing consumer demand for healthful, natural products.” The oats are marketed as “100% natural,” and the Quaker Oats website tells consumers that oats, which are a very hearty crop, “require less herbicide spray than many other grains.”

The suit puts the growing controversy over glyphosate (and, to a lesser extent, “natural” labels, which are not regulated) in front of the courts. While the class-action status of the complaint seeks financial damages, the larger question is twofold: Why is glyphosate showing up in oats and so many other foods, and does it present a health risk?

Those questions don’t lead to straightforward answers, and part of the reason why is that regulators have not been looking for glyphosate. Despite it being the most heavily used pesticide in history—with 2.4 billion pounds of it sprayed on U.S. farmland between 2004 and 2014—the Food and Drug Administration does not test for glyphosate residue, although it will begin to later this year. The Environmental Protection Agency, which is tasked with setting residue limits for pesticides, increased the threshold for glyphosate a few years ago.

“The [IARC] announcement has definitely raised the profile of glyphosate considerably for a lot of people, and it has kind of brought to light how little independent science has been at play with this chemical,” said Bill Freese, science policy analyst at the Center for Food Safety, which advocates for policies like labeling GMOs and limiting pesticide use. As he noted, the EPA found glyphosate to be carcinogenic in the 1980s but later reversed its claim. In the decades since, the agency has increased the overall safe exposure level—the cumulative exposure from residues on food—from 0.1 milligram of glyphosate per kilogram of body weight to 1.75 milligrams.

Monsanto, unsurprisingly, maintains that glyphosate is safe both for farmers and in the small amounts consumed by consumers. On its website, the chemical company writes, “Comprehensive toxicological studies in animals have demonstrated that glyphosate does not cause cancer, birth defects, DNA damage, nervous system effects, immune system effects, endocrine disruption or reproductive problems.”

But even with the WHO designation, the EPA’s easing of limits, and the FDA’s nonexistent testing regime, it is by no means a foregone conclusion that glyphosate is going to give all of us—or any of us—cancer. IARC’s mandate is very narrow in making the “probable carcinogen” designation: The experts are tasked with determining whether a chemical like glyphosate could cause cancer in some context, even if that context is rare.

Much like other research on pesticides and health, the glyphosate designation from IARC was not based on long-term studies of low-dose exposures. Rather, the research examined was on “mostly agricultural” exposures, which involve far higher concentrations of a chemical than we’re exposed to when eating foods that contain pesticide residues. “The general population is exposed primarily through residence near sprayed areas, home use, and diet, and the level that has been observed is generally low,” according to IARC.

This is common for pesticide research and regulation, where “the dose makes the poison.” The long-term effect of a lifetime of low-dose exposures to glyphosate, or most other commonly used pesticides, simply is not known.

That makes the very low levels of glyphosate found in foods throughout this recent bout of activist testing a little less comforting. Freese pointed to a 2006 study published in The Annals of Occupational Hygiene that tested pesticide levels in the urine of farm and nonfarm families in Iowa. While the men in farming families—who, generally speaking, do more of the agricultural work in the Midwest—had higher levels of some pesticides, glyphosate levels were the same across both groups.

“That would suggest that food residues—which are common to both farmers and non-farmers—is a major exposure pathway,” said Freese.

In the Quaker lawsuit, the question isn’t about the dose but the herbicide’s very presence, small as it may be. “The issue is that Quaker advertises these products as 100 percent natural, and glyphosate in any amount is not natural,” lawyer Kim Richman, who is representing the plaintiffs, told The New York Times. The trace amount of weed killer found in the product may be the result of farmers using glyphosate as a desiccant to speed up their harvest.

“It’s basically challenging Quaker Oats’ campaign that this is 100 percent natural—and that of course doesn’t rest on whether it is safe or not,” said Freese. “It is not legitimate to say that something is natural when it is being sprayed with a synthetic herbicide.”

As for the larger question of glyphosate use and residues and public health, Freese said, “We definitely need more testing—that’s part of the equation, and I think we need restrictions on use. I don’t think we’re ready to say glyphosate should be banned, but I think we should take a step back and take an overall look at how we use pesticides in America.”

This article originally appeared on TakePart.com. Reprinted with permission.

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