Common Herbicide Used In Monsanto’s Roundup Deemed ‘Probably Carcinogenic’

The widely used herbicide glyphosate, sold by Monsanto as Roundup, is “probably carcinogenic to humans,” concludes an evaluation by the World Health Organization’s cancer arm—the International Agency for Research on Cancer (IARC).

Monsanto is strongly disputing the assessment, which was published online on March 20 (Lancet Oncol. 2015, DOI: 10.1016/s1470-2045(15)70134-8). The company claims that the determination is not supported by scientific data.

“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,” says Philip Miller, vice president of global regulatory affairs at Monsanto.

IARC evaluated evidence of human exposures, mostly in agricultural workers, in the U.S., Canada, and Sweden published since 2001. The agency found “limited evidence of carcinogenicity in humans for non-Hodgkin lymphoma.” There is “convincing evidence that glyphosate also can cause cancer in laboratory animals,” IARC reported.

Use of glyphosate in agriculture has increased dramatically since the introduction of crops—specifically, soybeans and corn—that are genetically modified to resist the herbicide. The chemical has been detected in the “air during spraying, in water, and in food,” according to IARC, but the “level that has been observed is generally low.”

In response to the report, the Environmental Working Group (EWG) and other consumer advocacy organizations are calling on the Food & Drug Administration to require mandatory labeling of foods that contain genetically modified organisms (GMOs). “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,” said Ken Cook, president and cofounder of EWG.

Monsanto is urging WHO officials to meet with regulatory agencies around the world to examine the scientific studies used in the IARC analysis and to account for studies that the IARC work omitted. The company asserts that IARC selectively chose particular studies and disregarded the most relevant data.