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Scientists review exposure to glyphosate

Scientists review exposure to glyphosate

Experts found glyphosate in human diets well below acceptable daily intake 

By Jackie Clark
Staff Writer 

A group of scientists from Bayer recently published an exhaustive review of data about glyphosate residues and the potential for exposure through food. 

The paper, titled ‘Residues of glyphosate in food and dietary exposure,’ concludes that dietary exposure to glyphosate is well below limits set by toxicology studies. It was published August 16 in Comprehensive Reviews in Food Science and Food Safety. 

To come to this conclusion, the authors combed through publications from academic researchers, regulatory agency reports, risk assessments and even mainstream media reports.

“We were very concerned that the public sees the media reports and they just go out un-analysed,” John Vicini told He’s the regulatory policy and scientific affairs lead for food and feed safety at Bayer, and lead author on the paper. 

Often media reports will say that glyphosate was detected in food, “not putting those levels into any sort of context,” Vicini explained. “We felt that because of all those articles that we really needed to take a comprehensive look at that subject.”

One particular claim caught the attention of Vicini.  

“There was an internet site that posted information going back quite a few years ago on glyphosate in breast milk,” he said. “I’m an animal scientist, and so when we saw that paper, we looked at it and said ‘this doesn’t even really make any sense.’”

Once investigated, the Bayer scientists noticed that study had used an assay (a scientific protocol to determine the content or quality of a substance) that had no validation. 

“We actually went out and talked to a couple faculty members with speciality in lactation,” Vicini explained. “They eventually did a study with human subjects, and when they did a validated assay, they did not detect glyphosate.” 

That original study “has been repeated now at least five times, and people have not found, even with very accurate assays, that glyphosate is present in milk,” he added. 

In many cases, when headlines about glyphosate are in the news, “somebody measured something, they don’t tell you how they measured it, they don’t tell you how they sampled it, and they give a number and say ‘this is alarming,’” Vicini said. 

In reality, a lot of context and research goes into analysing glyphosate in food. 

“When you go to get a pesticide approved you do field studies that are designed to look at efficacy, environmental impact, but also residues,” Vicini explained. “What are the residues when you use it in a way the farm would actually use it?”

After that, “toxicology studies look at human health. After you do those you establish a safe level based on animal studies,” he adds. Then scientists go back and look at residues and the maximum amount you could expect to see in a human diet. 

“If they’re too high it’s not going to be approved,” he said.  As new uses for a product are introduced, scientists return and repeat the risk assessment. 

Those assessments always assume highest likely exposure, to ensure the product would be safe even in those cases. 

“If a particular agriculture practice has the highest residue, the assumption is made that all crops are grown with that practice. So, it’s a very conservative system,” Vicini explained. “All of that analysis always assumes that all crops are grown with the highest use, so it doesn’t matter if a new use becomes more popular.”

In addition to looking at residue data, Vicini and his colleagues investigated dietary exposure. 

“One way to do the dietary modelling is to just make assumptions about what people eat,” he explained. “We also then looked at urine, because urine is a way to not make those assumptions, it’s looking at what’s actually been consumed.”

What they found was that those two values “were amazingly similar,” he said. And, importantly, “glyphosate was less than three per cent of what’s considered to be the safe level for lifetime consumption.” 

They compared the results to both U.S. and EU values of safety because the EU regulations tend to be stricter. In either case, potential rates of dietary exposure to glyphosate were well below the established safe levels. 

“People have this feeling that glyphosate is ubiquitous and that they’re getting large amounts of these residues, but they’re actually very low compared to the safe levels,” Vicini explained. 

Surveys by regulatory agencies over the years have shown that farmers are following product labels, and so regulations based on studying safe limits and maximum residues are accurate.

“Between farmers following the label and what we know about safe levels, we couldn’t find anything to be concerned about in this study,” Vicini said.  

Also, “when it comes to meat, milk and eggs, there are no glyphosate levels,” he explained. “It really is no surprise because of the physiology of animals, and our own physiology too. Glyphosate does not bioaccumulate in people or animals.”

Vicini and his colleagues work together to analyse research published about glyphosate and investigate any claims or methodologies that need addressing or replicating to verify results. The other authors on this paper included Pamela Jensen, an analytical chemist, John Swarthout, a cell biologist, and Bruce Young, a market basket and regulatory agency survey expert. 

“We always hear ‘you’re a Bayer author, so how can I believe you?’” Vicini said.

However, the research in the review is from already-published peer reviewed papers from regulatory agencies and academic researchers. 

“There’s nothing of ours in there except the calculations, and anybody can repeat those,” he explained.  

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