Weed killer in breakfast cereals: How dangerous is it?

Marc Daalder , Keith Matheny | Detroit Free Press

Show Caption Hide Caption Popular breakfast cereals, oatmeal may contain cancer-linked pesticide Your favorite cereal, instant oatmeal or granola bar might also contain the main ingredient for weed killer.

A scientific debate over the danger of Roundup herbicide has been reignited after a report identified potentially dangerous trace amounts of the chemical in oat-based breakfast foods.

Glyphosate, the active ingredient in Roundup, has been used to kill weeds for 40 years, according to manufacturer Monsanto. For most of that time, it hasn't been considered dangerous.

But that consensus might be changing. In March 2015, the International Agency for Research on Cancers determined that glyphosate is "probably carcinogenic to humans," meaning it has the potential to cause cancer.

That doesn't settle the debate. The agency's parent organization, the World Health Organization, found in May 2016 that glyphosate is "unlikely to pose a carcinogenic risk to humans from exposure through the diet."

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Wednesday's report from the nonprofit Environmental Working Group comes a week after Monsanto was ordered to pay nearly $300 million to a groundskeeper who alleged his use of the weed killer on the job had given him cancer.

The Environmental Working Group found glyphosate in all but five of 29 tested breakfast foods, prompting an outcry from those concerned with the overuse of pesticides on food.

What is glyphosate?

Glyphosate is applied to leaves to kill grasses and weeds. It is the most used agricultural chemical in the world and experienced a boom in use beginning in the 1990s, Newsweek reported.

Glyphosate use in agriculture previously was hampered because the product often killed not only weeds but the crops it was intended to protect. But in the 1990s, Monsanto began producing genetically modified crop strains resistant to glyphosate, so the herbicide could be applied without damaging the crop.

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Oats, a common grain in breakfast foods, are not modified for glyphosate resistance. Farmers often use the product on oats to kill the crops and dry them out to hasten harvesting.

At a conference two years ago, a federal Food and Drug Administration official mentioned the development of methods to determine glyphosate levels in food products and it was being found in oat products, said Alexis Temkin, an Environmental Working Group toxicologist and author of the glyphosate in breakfast foods study. That prompted her group's research.

FDA emails obtained under the federal Freedom of Information Act also showed references to glyphosate being found in a number of foods, but none of the information had been made public, she said.

Environmental Working Group sampling found glyphosate levels varying from 1,300 parts per billion in Quaker Old Fashioned Oats to undetectable in Nature's Path Organic Honey Almond granola. Glyphosate was found at up to 780 parts per billion in Quaker Dinosaur Eggs Brown Sugar Instant Oatmeal and up to 530 parts per billion in General Mills' Cheerios cereal.

The International Agency for Research on Cancers and the World Health Organization both stand by their conflicting positions on the herbicide. The cancer agency reaffirmed its view as recently as February and deflected allegations that it had weighed some research more favorably.

Other independent reviews have found similarly conflicting results. California officials issued guidelines in mid-2017, based on the cancer agency's research, to restrict the use of glyphosate because they worried that the chemical was carcinogenic.

The federal Environmental Protection Agency, as recently as December 2017, said glyphosate "is not likely to be carcinogenic to humans" and doesn't pose any other sort of health threat, either.

Scientific reports are also split.

• A November 2017 study from the National Institutes of Health found "no association was apparent between glyphosate and any solid tumors or lymphoid malignancies overall." However, it noted "there was some evidence of increased risk of acute myeloid leukemia among the highest exposed group that requires confirmation."

• A 2013 study found that glyphosate can induce the growth of breast cancer cells in humans.

• Another study from last year found links between applications of glyphosate and fatty liver disease in rats.

In a statement released Wednesday, Monsanto said the EPA has "consistently reaffirmed that glyphosate does not cause cancer." However, the EPA has found only that the chemical "is not likely" to be dangerous.

Thousands of people are suing Monsanto for cancer and cancer-related illnesses, the conglomerate told The New York Times.

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A jury in one lawsuit found last week that the agricultural chemical company should have done more to warn customers of Roundup's potential risks and awarded Dewayne Johnson $289 million. Johnson, 46, of San Francisco, has terminal non-Hodgkin lymphoma, the cancer most frequently linked to glyphosate.

As a former groundskeeper at a San Francisco-area school, Johnson said he sprayed weed killer often, sometimes for hours at a time. He is a father of three, and his wife testified that she has had to work 14-hour days to cover Johnson's medical expenses.

The jury in his case determined Monsanto was guilty of "negligent failure" for not making clear its product might be dangerous. Monsanto plans to appeal and disputes the jury's findings, saying Roundup had nothing to do with Johnson's cancer.

How much is too much?

Beyond the debate over whether glyphosate can cause cancer is a difference of opinion over at what levels it becomes potentially unsafe.

Monsanto noted that even the highest detections of glyphosate in oat products in the Environmental Working Group study are at least 100 times below EPA recommended safety limits.

"Even at the highest level reported by the EWG (1,300 parts per billion), an adult would have to eat 118 pounds of the food item every day for the rest of their life to reach the EPA’s limit," the company stated in a release.

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But whether that EPA limit is set where it should be to protect public health is disputed. The EPA finds that people should be able to safely consume 2 milligrams of glyphosate for every kilogram, about 2.2 pounds, of body weight every day.

The European Union has a more rigorous standard, limiting intake to 0.3 milligrams of glyphosate for every kilogram of body weight per day. A milligram is so small that more than 28,000 milligrams equal just 1 ounce; a drop of water weighs about 50 milligrams.

So someone who weighs 154 pounds, almost 70 kilograms, would be able to ingest about 140 milligrams of glyphosate using EPA standards, but fewer than 21 milligrams using European Union standards.

California, which implemented its own standards last year, set a limit 125 times more strict than the EPA. The state's Office of Environmental Health Hazard Assessment says that an adult weighing 154 pounds can safely consume just 1.1 milligrams per day, about 0.016 milligrams per kilogram.

Any more than that poses a 1-in-100,000 cancer risk, according to California state scientists.

Finally, the Environmental Working Group has proposed its own modified version of California's guidelines. First, the group noted that California usually bases its standards on a 1-in-a-million cancer risk and altered its suggested standard accordingly. This means that the environmental organization's recommendation for adults' safe consumption is 0.1 milligrams per day — about 0.0014 milligrams per kilogram of body weight.

Meanwhile for children, the environmental group recommends an additional tenfold margin of safety, based on federal guidelines in the Food Quality Protection Act. So the Environmental Working Group argues that children can safely consume only 0.01 milligrams of glyphosate per day.

Realize this: Virtually no food is free of contamination. The FDA allows an average of 9 milligrams of rat poop per kilogram of wheat, about 5½ cups, saying it's a natural or unavoidable defect that presents no human health hazard.

That means two servings of wheat, not wheat flour, of 40 grams each, which is about a heaping cup, can have as much as 0.36 milligrams of rodent feces and meet federal standards.

"When we're thinking about children's products and children's exposure, the most health-protective value for children is most appropriate," Temkin said.

What about the food?

Food rarely violates the European Union and California standards and virtually never violates the EPA's standard.

The Food and Drug Administration, which is responsible for ensuring that food adheres to EPA guidelines, told The New York Times that none of its 2016 tests found violations. 2017 tests still are being evaluated.

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The food in the Environmental Working Group study much more consistently violated the environmental group's benchmark for children – 16 of the 29 products were found to be above the children's standard in at least one test.

The adult standard never was violated. The closest was Quaker's Old Fashioned Oats, which an adult would have to eat a little more than two servings of 40 grams daily, about a heaping cup total, to be at a heightened health risk, according to the environmental group.

In a statement, Quaker officials said their oats are thoroughly cleaned once they arrive from the field.

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"Any levels of glyphosate that may remain are significantly below any regulatory limits and well within compliance of the safety standards set by the Environmental Protection Agency and the European Food Safety Authority as safe for human consumption," according to the company.

General Mills, makers of Cheerios, echoed Quaker.

Our products are safe, and without question they meet regulatory safety levels.



The EPA has researched this issue and has set rules that we follow as do farmers who grow crops including wheat and oats. We continue to work closely with farmers, our suppliers and conservation organizations to minimize the use of pesticides on the crops and ingredients we use in our foods.

The Environmental Working Group called for increased awareness and changes in agriculture and food production.

"We're really looking for consumer education and company action, in terms of digging through their supply chain (and) working with farmers that don’t use glyphosate pre-harvest applications," Temkin said.

Follow Marc Daalder and Keith Matheny on Twitter: @marcdaalder and @keithmatheny

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