If you've read the news lately, you've probably wondered if you should worry about herbicides in your food. We all want to know that what we’re eating is safe. And by now we can be pretty confident that when we go to the store or sit down at a restaurant that whatever we put in our mouths won’t be bad for our health or kill us (save the rare outbreak of norovirus in your burrito bowl that merely makes one pray for death). So it’s understandably shocking to hear that those of us who think breakfast is the most important meal of the day may be slowly poisoning our bodies with a weedkiller present at high levels in our cereal.
Wait, what? Let’s back up a bit.
Chances are you’ve heard of Roundup, the herbicide popular with both farmers and homeowners and owned by Monsanto, the now dissolved (and acquired by Bayer) agricultural company. The active ingredient in this weedkiller is an herbicide known as glyphosate. Recently the Environmental Working Group (EWG), an advocacy group that has been accused of having a bias against conventional farming, released a report warning consumers about the “hefty dose” of glyphosate in popular breakfast foods like cereal, oatmeal, and granola bars. The findings seem, at face value, very worrisome: of the 61 products tested, 31 had levels of glyphosate above the EWG’s acceptable threshold. All of the seemingly high-glyphosate-containing products were conventional, not organic.
But what the EWG’s report didn’t mention is that the levels were calculated to be 100 times lower than even the lowest proposed state governmental standard (California wants to place limits on glyphosate that are lower than even the current EPA standard). Although the FDA is currently doing additional testing on herbicide residues in foods before it officially releases its findings, the agency’s current established tolerance for glyphosate in foods is between 0.1 and 310 parts per million (ppm). According to the EWG, the highest amounts of glyphosate found were .53ppm in Cheerios and 1.3ppm in Quaker Old Fashioned Oats. Both amounts are well within the acceptable range of what the EPA considers the acceptable limit. The report also didn’t clarify that levels of Roundup found in cereal were about as trace as any other herbicide (organic or conventional) you’d find in your food. This is important because, as any scientist will tell you, dose matters.
There’s no reason to believe that ingesting glyphosate at well under established EPA levels is unsafe.
By all measures, glyphosate, the active ingredient in the herbicide Roundup, according to the EPA, has low toxicity for humans.
Poisons are both species- and dose-specific. A well known example of species specificity is theobromine in chocolate, which is toxic to dogs but not at all for humans (thankfully). Antibiotics in the appropriate dosage kill bacteria, but not you. Just because herbicides kill plants very well, we can’t assume that means they kill humans just as well, or at all. Roundup is pretty bad for weeds because it’s targeted to inhibit a specific enzyme that’s necessary to synthesize protein, and this pathway just doesn’t exist in humans.
But we’re talking about long term, chronic toxicity, not an acute poisoning. I get that the question isn’t if eating one bowl of cereal will kill you. Though most people don’t contest the relatively low toxicity of an acute exposure to Roundup, the concern about Roundup’s effects is more regarding long-term carcinogenicity—that is, if eating a bowl of your favorite Roundup-tinged cereal every day will eventually give you cancer. You feel fine now, but the question lurks if it causes you to be sick years from now. Let’s look at the evidence here.
Glyphosate fear was recently in the news again when a jury ordered Monsanto pay $289 million to a groundskeeper who had developed cancer.
The plaintiff, Dewayne Johnson, was a California groundskeeper who regularly used Roundup. He has a kind of cancer called non-Hodgkin’s lymphoma, and according to reporting by the Guardian, has months to live. The jury found that Johnson’s use of Roundup, which his attorneys estimated happened at a rate of 20-30 times per year, led to his terminal cancer.
The American Cancer Society, however, has stated that the causes of most cases of non-Hodgkin lymphoma are unknown. Unlike diseases where you can test for presence of toxins or microbes that cause the illness, you can’t remove a tumor or examine someone’s blood and find a smoking gun. In this case, Johnson had to prove that he wouldn’t have gotten cancer without his exposure to Roundup. Johnson’s attorney, Timothy Litzenburg, maintained that glyphosate on its own is not carcinogenic per se, but that it became so when mixed with the other ingredients in Roundup.
Monsanto has said that it will appeal the case, saying that at this point, with over 800 studies on it, no study has shown the components in Roundup to cause cancer.
If no studies have found a causal link between glyphosate and cancer, where is the idea that glyphosate is unsafe coming from?
You may have heard news reports that the International Agency for Research on Cancer (IARC) classified Roundup as a probable carcinogen. The IARC is part of the World Health Organization (WHO), so its findings seem pretty legit. But let’s unpack this a bit.
When the IARC report came out defining glyphosate as a probable carcinogen, it didn’t just raise the ire of giant agricultural firms. A large swath of scientists, journalists, and both Americanand European environmental organizations voiced their disagreement with the IARC. WHO, of which the IARC is a subsidiary, disagreed with their analysis, finding in their own joint analysis done with the United Nations Food and Agriculture Organization, that glyphosate was “unlikely to pose a carcinogenic risk to humans from exposure through the diet.” Though the IARC’s report was on overall exposure and not just through diet, one of the largest epidemiological studies on Roundup toxicity somewhat rectifies this by studying about 52,000 people who apply glyphosate regularly, including farmers, found that “no association was apparent between glyphosate and any solid tumors or lymphoid malignancies overall, including NHL and its subtypes.” Additionally at this point, there haven’t been major credible studies showing a causal link between Roundup and cancer.
So...is it okay for me to stop worrying about Roundup in my food?
Roundup was not the first herbicide to grace our amber waves of grain, and it seems to be less toxic to humans than its predecessors. As the popular science blogger Credible Hulk explains using data from the U.S. Geological Survey, as Roundup’s popularity has increased, use of older, more toxic agricultural chemicals has decreased. Furthermore, only about a half a pound of glyphosate is sprayed on an average acre of crop.
Whether or not you think that any amount of glyphosate in food sounds unsafe, I’d take a look at the evidence that informs every major environmental and health organization in the world. When used correctly, the trace amount detectable in food is, by all measures, harmless. Should you drink it? No, but you also shouldn’t drink other things that you’re exposed to regularly (personally, I will pass on drinking my body wash, but I don’t know your life). Species, route of exposure, and quantity matter, and by all these measurements, this is something you can stop worrying about.
Yvette d'Entremont holds a B.S. in chemistry, B.A. in theatre, and a master's degree in forensic science with a concentration in biological criminalistics. She worked for eight years as an analytical chemist before her blog focused on debunking bad science, scibabe.com, turned into a full-time job in science communications. Follow her on Twitter and Facebook.