A recent study by the World Health Organization reached a startling conclusion–the active ingredient in Roundup, the nation’s most popular weed killer, might put farm workers at increased risk for cancer.
The study, published by the WHO’s International Agency for Research on Cancer, found that Roundup’s active ingredient, a chemical called glyphosate, was a probable carcinogen–the second-highest classification the WHO uses for cancer. Roundup is particularly popular in commercial agriculture settings. The IARC study found that glyphosate is likely absorbed into the body; it has been found in the blood and urine of agricultural workers. Ever since Roundup’s manufacturer, Monsanto, introduced glyphosate as an herbicide in 1974, it has adamantly maintained that glyphosate? does not cause cancer. Needless to say, this report came as an unwelcome surprise at Monsanto headquarters near St. Louis.
Based on three studies of farm workers, the IARC concluded that occupational exposure to glyphosate can cause heightened risks for non-Hodgkin lymphoma.? Further studies found that glyphosate can cause DNA and chromosomal damage in human and animal cells. On that basis, the IARC concluded that glyphosate was “probably carcinogenic to humans” in an industrial setting. IARC spokeswoman Janet Guyton told the Associated Press that her colleagues couldn’t find any evidence as of yet that the consumer version of Roundup carried a risk of cancer. However, she said, it was “something to be conscious of.”
Charles Benbrook, a researcher at Washington State University, was surprised by the WHO report. He told Mother Jones that while he had long believed glyphosate was a “relatively benign” herbicide, he wouldn’t have been suprised if the WHO declared it a “possible” carcinogen. “‘Probable,’ I did not expect,” he said. Given that detectable levels of glyphosate have been found in air, rain, and streams in areas where it is frequently used, Benbrook believed it was a near-certainty that the EPA will be under pressure to demand more tests. The EPA has long maintained that there is no conclusive evidence that glyphosate can cause cancer, but said that it would “consider” the WHO’s findings. Monsanto’s stock dropped by two percent on Monday, and is aggressively challenging the WHO’s findings. Notably, Monsanto claims that the WHO study flies in the face of all available scientific literature and regulatory reviews.
Even if Roundup isn’t a carcinogen, a lot of evidence suggests that its longtime slogan–“No root. No weed. No problem”–is grossly inaccurate. The EPA’s fact sheet on glyphosate notes that long-term exposure at heightened levels can cause kidney damage, reproductive problems, and lung congestion. So even if Monsanto does manage to weather this storm, there may be more on the way in the future.