The controversial herbicide glyphosate will be permitted in the European Union for five more years, after Germany's agriculture minister changed his vote — a move that angered Germany's allies and threatened internal coalition-building, but satisfied European farmers who had worried about a threat to their business.

Glyphosate, known by trade name Roundup, is widely used in large-scale commercial farming, as NPR's Dan Charles explained in 2015.

"Farmers like it because many crops, including corn, soybeans and cotton, have been genetically modified to tolerate the chemical," Dan wrote. "Farmers can spray it across entire fields, killing weeds while their crops survive."

Roundup, which was invented by Monsanto, used to be considered one of the least toxic herbicides available for farmers, Dan says. But in 2015, a U.N.-sponsored group of cancer experts said that the herbicide is "probably carcinogenic to humans."

Other organizations — including the U.S. Environmental Protection Agency and a committee of the European Food Safety Agency — have concluded that the chemical probably is not carcinogenic. Monsanto has also vigorously denied that the chemical poses a threat. As Dan reported this spring, the company's efforts to defend itself included offers to "ghostwrite" a scientific paper, to be ostensibly published by an outside scientist. That offer was revealed after cancer patients sued Monsanto, alleging collusion with the EPA to downplay Roundup's risks.

The scientific debate over the safety of glyphosate led to a fierce political debate in Europe. For two years, the European Union fought over the future of the license allowing farmers to use glyphosate, Reuters reports.

After months of deadlock in the EU, a German minister changed his position and voted in favor of the five-year extension. That allowed the measure to pass "by the narrowest possible margin," Reuters says.

Germany joined many countries in Northern and Eastern Europe that supported an extension of the license, Politico EU says. Farmers across Europe say they have no cheap, equally effective alternative to the weedkiller, as the news site has previously reported.

But the vote switch meant defying France and Italy, which have raised concerns over possible environmental impacts of glyphosate, as well as the potential cancer risk.

The change in vote "is poisoning German politics," Politico EU writes, as it prompts a domestic backlash and creates a headache for German Chancellor Angela Merkel.

Merkel has been struggling to build a ruling coalition ever since her party lost ground in September's elections. She is trying to coax participation from the Social Democrats — who fiercely opposed the extension of the glyphosate license.

German Environment Minister Barbara Hendricks, a Social Democrat, publicly objected to the vote by Agriculture Minister Christian Schmidt. She told The Associated Press, "Anyone who is interested in developing trust between two parties cannot behave that way."

Merkel has scolded Schmidt for his vote, saying that it "did not comply" with instructions he received and that she expects "such an incident will not be repeated," Reuters reports. (Normally, if ministers in the government disagree on an issue like this, Germany would abstain from an EU vote instead of taking a side, the wire service explains. Schmidt violated protocol.)

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