healthHealth and Medicine

Common Breakfast Cereals Have Traces Of Weed Killer. Should You Be Worried?


Dr. Alfredo Carpineti

Senior Staff Writer & Space Correspondent

clockAug 17 2018, 11:45 UTC

Julia Sudnitskaya/Shutterstock

The Environmental Working Group (EWG), an American pressure organization, has released a study on the concentration of glyphosate, a widely used weed killer, in common breakfast oat cereals, granola, and snack bars. This has led to a flurry of headlines on the dangers of eating these products (especially for children), so we think it’s important to clarify the science of glyphosate in cereals.

First things first: All of the 45 products analyzed by the EWG have values way below the legal limit, and even in the most “contaminated” product, glyphosate did not exceed 1300 parts per billion. EWG rightly states that legal doesn’t mean safe, but it is important to remember that it also doesn’t mean unsafe.


Glyphosate has been in the news recently because of a court case. Last week, a California jury ordered Monsanto, the manufacturer of the most common glyphosate herbicide, to pay $289 million in damages to a man dying of cancer. He was a groundskeeper and used the company’s Roundup herbicide regularly.

But a court case and getting money from an infamous corporation doesn’t make or unmake the science. According to the International Agency for Research on Cancer, part of the World Health Organization, glyphosate is probably carcinogenic. Does this mean it's bad? Well, it does and it doesn’t. Eating red meat, being near frying oil, drinking very hot beverages (about 65°C/150°F), as well as being a hairdresser or a barber has the same classification.

The key here is dosage. Water and oxygen are indispensable for life, but too much can lead to death. Sea salt is needed by our body in low doses, but it’s bad for us in high doses. Similar toxic substances might have no detectable effects until they reach a certain threshold.


"For the average food consumer no studies have found evidence of the levels of glyphosate around us or in our food or water causing any reason to be worried about increased risk of cancer," Dr Robert O'Connor, head of research for the Irish Cancer Society, wrote in a post just a few days ago.

According to the World Health Organization, ingesting doses of up to 2 grams of glyphosate per kilogram of body weight did not have any genotoxic effect (alteration of the DNA) and it put a strict limit of 1 milligram per kilogram of body weight per day. For the average adult, you’d need to eat about 1,000 servings (60 grams) of oat cereals a day to exceed that limit. If you do that, glyphosate is the least of your worries.

We contacted the European Food and Safety Authority (EFSA) and a spokesperson said they cannot comment on an individual study. In the European Union, the maximum daily dosage of glyphosate is 0.5 milligrams per kilogram (half of the WHO recommendation) and EFSA has put a maximal residual limit (MRL) at about 0.1 milligrams per kilogram. In a 2016 document, the EFSA reports that out of 6,761 samples analyzed by the EU governments, only 19 exceed the MRL. No oat product was anywhere near this limit, and out of 185 tested, 153 had no quantifiable pesticides in them. 


EWG uses the State of California limit, which is much stricter, of 1.1 milligrams per day as a maximum dosage for a 70-kilogram (154-pound) adult – about 17 servings per day. They then state that they want the increase risk calculation to be one-out-of-1-million rather than the standard of 1-out-of-100,000 people, so they divide the number by 10 and then by 10 another time to adjust for the children’s health safety factor. They end up with a number of 160 parts per billion, which poses a one-in-a-million cancer risk for children. This calculation leads to the EWG recommended dose, which is 0.01 milligrams per kilogram.

That number is arbitrary. The standard risk calculation out of 100,000 people would let all the tested products pass. The EWG number only let organic products pass, some of which also have traces of glyphosate. Evidence supporting the hypothesis that glyphosate is cancerogenic is far from solid and the idea that any of the doses reported in the tests pose a health risk is misleading. And if you’re going for the “Why won’t anyone think of the children?” route, you better take away their burgers and hot cocoa as well as their oatmeals.

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