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There's No Proof Roundup Causes Cancer But Questions Linger

There's No Proof Roundup Causes Cancer But Questions Linger

(Bloomberg) -- The world’s regulators agree that the active ingredient in popular weedkiller Roundup is unlikely to cause cancer. Yet manufacturer Bayer AG keeps losing in court to plaintiffs who say it gave them the disease.

So is glyphosate, the world’s most widely used weedkiller, really dangerous?

There’s no proof that the chemical causes cancer in humans. Regulators in the U.S., European Union and elsewhere have said it probably isn’t a carcinogen, and more than 800 studies back that up, including an epidemiological study undertaken by the National Cancer Institute that found glyphosate use wasn’t associated with overall cancer risk. Tina Levine, a former director of the Health Effects Division of the Office of Pesticide Programs in the U.S. Environmental Protection Agency, said human health concerns were minimal.

However, the International Agency for Research on Cancer in France, part of the World Health Organization, classified glyphosate as a “probable” carcinogen in 2015, in a lower level risk category that includes many other common substances including red meat. Despite the inconclusiveness, that’s what has opened the door to the lawsuits farmers and other heavy users of the chemical are bringing.

The translation of IARC’s classification is that it’s something “to keep an eye on and limit exposure to, because there may be a link to some other carcinogenic stimulus,” said Ricardo Salvador, director of the Union of Concerned Scientists’ food and environment program.

It’s not just farmers who spray billions of pounds of glyphosate annually that should pay attention to glyphosate. Because it’s used in such great quantities, the chemical is now ubiquitous, and “you’ll find it wherever you go measuring for it,” Salvador said, whether that’s in food or in humans. Trace amounts have been found in everything from ice cream to orange juice. There’s a new, emerging area of study that’s looking at the impacts of long-term exposures at low levels, according to Salvador.

Little is known about chronic exposure to glyphosate at small amounts.

“We don’t have sufficient data, so let’s get the data,” Salvador said. “The jury is still out, not because we don’t know the experiments to do, but because the questions are new.”

Glyphosate has been a blockbuster product for Monsanto Co. since it was introduced in the 1970s. The vast majority of U.S. corn and soybeans have been genetically modified to withstand it, making it a critical component of modern farming. Bayer bought Monsanto last year for $63 billion.

--With assistance from Naomi Kresge and Tim Loh.

To contact the reporter on this story: Lydia Mulvany in Chicago at lmulvany2@bloomberg.net

To contact the editors responsible for this story: James Attwood at jattwood3@bloomberg.net, Millie Munshi

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