Monsanto's popular weedkiller is mainly used on crops such as corn and soybeans, which are genetically modified to survive it. It also"probably causes cancer" in humans, says IARC.

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Glyphosate, Favored Chemical of Monsanto & Dow, Declared 'Probable' Source of Cancer for Humans

World's most widely used herbicide ingredient shown to cause variety of cancers by research arm of World Health Organization

In a determination that could have far-reaching implications for the agro-chemical giants like Dow Chemical and Monsanto, the research arm of the World Health Organization has declared that glyphosate--the key ingredient of widely-used herbicides such as Roundup--should now be categorized as a "probable carcinogen" for humans.

In a report published on Friday in The LancetOncology medical journal, the International Agency for Research on Cancer (IARC), based in France, announced its findings after a meeting of 17 oncology experts from 11 countries met to review the available scientific research exploring the connection between glyphosate, as well as several organophosphate insecticides, and various human cancers.

"Consumers have the right to know how their food is grown and whether their food dollars are driving up the use of a probable carcinogen." --Ken Cook, EWGAccording to IARC, glyphosate is used in more than 750 different herbicide products and its use has been detected in the air during spraying, in water and in food. The panel of experts concluded that "limited evidence" exists to show the herbicide can cause non-Hodgkins lymphoma in humans and additional "convincing evidence" that it can cause other forms of cancer in both rats and mice. Researchers noted that glyphosate has been found in the blood and urine of agricultural workers, showing the chemical has been absorbed by the bodies of those who work most with it.

As the Associated Pressexplained, the research agency--which provides academic and scientific research FOR the WHO--has four levels of risks for possible cancer-causing agents: known carcinogens, probable or possible carcinogens, not classifiable and probably not carcinogenic. Glyphosate now falls in the second level of concern.

Though Monsanto immediately and predictably rejected the findings of the IARC, scientists who have long-warned of the public health impacts and wider dangers of glyphosate say the announcement should add urgency to the debate about whether or not such products should be allowed to dominate the world's agricultural systems.

"The widespread adoption of GMO corn and soybeans has led to an explosion in the use of glyphosate - a main ingredient in Monsanto's Roundup and Dow's Enlist Duo," said Ken Cook, president and co-founder of the Environmental Working Group. "Consumers have the right to know how their food is grown and whether their food dollars are driving up the use of a probable carcinogen."

Emily Marquez, Ph.D., a staff scientist at the Pesticide Action Network, in a statement on Monday, said, "Given glyphosate's widespread usage with crops genetically engineered to tolerate herbicides, IARC's finding comes none too soon."

"This increasingly dangerous pesticide treadmill calls into question the logic of genetically engineered herbicide technologies that rapidly lose their utility to farmers and put human health at risk." --Emily Marquez, Pesticide Action Network

Though the IARC's finding have no regulatory bearing on the U.S. Environmental Protection Agency determinations about glyphosates and the other compounds studied, they do add weight to the body of evidence showing how harmful such chemicals are.

According to Marquez and her colleagues at PAN, since Monsanto's signature "RoundUp Ready" corn and soy crops were introduced in 1996, more than 500 million additional pounds of glyphosate and other herbicides have been used in the United States.

"It should be noted that in well over a decade's use of glyphosate in GE crops, hundreds of millions of pounds of this chemical have been released into the environment," said Marquez. "USGS surveys document widespread water contamination, and -- as documented in a recent Consumer Reports study -- residues of glyphosate also show up in our food. Even though glyphosate is so widely used, the U.S. does not currently conduct biomonitoring for glyphosate residues, and USDA conducts only minimal testing for food residues."

What's more, the pesticides and herbicides on which farmers have now been forced to rely may no longer be working. As Marquez explains: "The dramatic growth in herbicide use in the U.S. driven by GE technology has resulted not only in increased human exposure to these chemicals, but also in the development of herbicide-resistant 'superweeds.' Farmers are offered more toxic mixes of herbicides as a so-called solution to this new problem. Dow's recently approved Enlist seeds -- designed for use with a mixture of glyphosate and the antiquated, highly toxic herbicide, 2,4-D -- offer a case in point."

In other words, the more these chemicals are used, the less effective they become.

According to Marquez, "This increasingly dangerous pesticide treadmill calls into question the logic of genetically engineered herbicide technologies that rapidly lose their utility to farmers and -- as IARC's recent finding makes clear --put human health at risk."

As Al-Jazeera notes, scientists and farmers from around the world have raised other concerns over glyphosate and tried to ban its use:

Channa Jayasumana,with Rajarata University of Sri Lanka, published a study in the International Journal of Environmental Research and Public Health in 2014on a possible link between glyphosate and chronic kidney disease in farmworkers. His research found that excessive heat and dehydration may weaken the workers' bodies, making them more susceptible to pesticides and heavy metals, which can lead to kidney disease.

Based on that research, the Sri Lankan government moved to ban glyphosate in spring of 2014. But Monsanto raised objections to the report's findings, and the ban was lifted. The chemical was, and continues to be, widely used on farms in the country.

The research also suggested a link between glyphosate and a mysterious kidney disease that has killed thousands of farmworkers in Central America. At least 20,000 farm workers have died of chronic kidney disease in Nicaragua in the last two decades, The Guardian reported in February. Researchers who have studied the disease in Central America say that it mainly affects agricultural laborers working under conditions of excessive heat and dehydration, but other factors, including pesticides, may play a role.

In addition, a peer-reviewed paper in 2014--titled "Genetically Engineered Crops, Glyphosate and the Deterioration of Health in the United States of America"(pdf)--linked glyphosate to a huge increase in the incidence of 22 chronic diseases across the United States.

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