The World’s Most Popular Weed Killer Can ‘Probably’ Cause Cancer

Since the first genetically engineered crops were approved for commercial production in the United States in the mid-1990s, GMO corn and soy have come to nearly dominate the industry. More than 90 percent of both crops are now genetically engineered, and GMO cotton, alfalfa, and sugar beets have enjoyed similar commercial success.

In many cases, the crops have been genetically modified to withstand the herbicide glyphosate, which Monsanto sells under the brand name Roundup. While there’s been endless emphasis on the possible—and as yet unfounded—health risks associated with consuming the GMO crops themselves, perhaps the focus should have been on the herbicide itself. The altered crops allow farmers to spray their fields and only kill unwanted weeds, a boon that has caused glyphosate use to skyrocket over the last two decades, jumping from 20 million pounds used per year in 1992 to more than 250 million pounds in 2011. On Friday, the World Health Organization’s cancer group, the International Agency for Research on Cancer, announced that it is “probably carcinogenic.”

According to a review of studies on agricultural chemicals published in the medical journal The Lancet, the group of international cancer researchers found “limited evidence” of glyphosate—the “highest global production volume herbicide” on the market—causing cancer in humans, specifically non-Hodgkin’s lymphoma. Studies of occupational exposure to glyphosate in the United States, Canada, and Sweden “reported increased risks for non-Hodgkin lymphoma that persisted after adjustment for other pesticides.” In studies of rodents, glyphosate has been linked with a number of cancers.

Monsanto, which pioneered the elegant business model of selling both a broad-spectrum herbicide and commodity crop seeds that are immune to it, quickly refuted the announcement. “We don’t know how IARC could reach a conclusion that is such a dramatic departure from the conclusion reached by all regulatory agencies around the globe,” Philip Miller, vice president of global regulatory affairs, said in a statement.

Indeed, in 2014 the Environmental Protection Agency increased the amount of glyphosate residue that can remain on fruits and vegetables. According to an EPA consumer fact sheet, the short-term health risks of glyphosate exposure are limited to “congestion of the lungs” and “increased breathing rate.” In the long term, according to the EPA, high levels of exposure can cause kidney damage and reproductive issues. “Glyphosate is even less toxic than the [bug] repellent you put on your children’s skin,” Pablo Vaquero, director of corporate affairs for Monsanto in Argentina, told The Associated Press in 2013.

The headline for that story? “Argentines link health problems to agrochemicals.” After the agriculture sector was opened up to GMO soy, corn, and cotton in 1996, rates of cancer and birth defects have spiked in rural regions that are increasingly dominated by soy farms. In Chaco province, there have been “regional birth reports showing a quadrupling of congenital defects, from 19.1 per 10,000 to 85.3 per 10,000 in the decade after genetically modified crops and their agrochemicals were approved in Argentina.”

Similarly, the herbicide is believed by some to be behind a little-understood kidney disease suffered by farmworkers in Central America. More than 20,000 people, predominantly men who work harvesting sugarcane, have died of kidney failure in the last 20 years, according to researchers at Boston University. Some believe that glyphosate exposure is at least partly responsible, although no scientific link has been established. A similar disease has cropped up in Sri Lanka, where the government briefly banned the sale of glyphosate.

While Dutch lawmakers have responded to health concerns by ending the sale of consumer gardening products containing glyphosate—which are widely available at garden centers in the United States—it’s unlikely that similar restrictions from the U.S. government will follow the WHO announcement.

According to the EPA, once again, “there is a reasonable certainty that no harm will result to the general population or to infants and children from aggregate exposure.” Unless glyphosate is indeed a carcinogen, that is.