With yesterday’s announcement by the World Health Organization that the active ingredient in world’s most widely used herbicide likely causes cancer, a natural question for consumers is whether the chemical glyphosate is present in their food. The product is also known under Monsanto’s trade name of Roundup.

Widely used by farms and home gardeners, little is known about its presence in the U.S. food supply as the federal government does not regularly test for it. Sold since the 1970s, glyphosate has increased in usage ten times in the last 20 years, thanks in large part to the rise in genetically modified (GMO) crops, especially soy and corn. Such plants were engineered to resist  Roundup, meaning glyphosate will kill unwanted plants (weeds) but not the GMO food crops. Last year, for every acre of active farmland in the United States, three-quarters of a pound of Roundup was applied.

Chuck Benbrook say yes, the likely carcinogen is indeed getting into humans via the food supply. He’s a professor at Washington State University’s Center for Sustaining Agriculture and Natural Resources. “When a single pesticide is used that widely,” he said, “people can’t help but be exposed to it.”

So-called “superweeds” have developed over the years that are resistant to Roundup. So the U.S. Environmental Protection Agency very recently approved a new herbicide by Dow Chemical Company, Enlist Duo, which combines glyphosate with another controversial chemical, 2,4-D. Bringing Enlist Duo into widespread use will result in even greater amounts of glyphosate in the ecological system. A 1987 report from the International Agency for Research on Cancer said that 2,4-D and variants are “possibly carcinogenic to humans.”

In one study, the U.S. Department of Agriculture discovered Roundup residues on approximately 90 percent of 300 samples of soybeans. Whether other foods are contaminated is not known.

Friday’s announcement came from The International Agency for Research on Cancer, a part of the World Health Organization. It said that glyphosate is “probably carcinogenic to humans.” Consumer Reports wrote that because Roundup is used so widely used – and also that its health effects are not well understood – it should at least be monitored by the government.