It was consternation then when the highly respected United Nation’s International Agency for Research on Cancer (IARC) recently declared it a ‘probable human carcinogen.’
Glyphosate is used in more than 750 agricultural, household and forestry products. It is also the main stay for genetically modified crops that are resistant to it. It is the world’s biggest selling herbicide, in use for almost half a century.
Monsanto chemist John E. Franz discovered glyphosate, a broad-spectrum systemic herbicide, in 1970. Monsanto brought it to the market shortly thereafter the under trade name Roundup. At the time N-(phosphonomethyl)glycine was hailed as a major advance in safe weed control, with an LD50 of 4,320 mg/kg. Only effective on actively growing plants, its use drastically expanded with the emergence of genetically modified crops, which are engineered to be resistant to it. However, the enormous use makes weed resistance a growing problem. Some concern was also raised about its alleged safety. Monsanto’s last patent in the United States expired in 2000.
Cornell University has noted that it can cause significant eye irritation. However, none or little chronic toxicity was found in tests with mice, rats, dogs and rabbits. The U.S. Environmental Protection Agency (EPA) has stated that there is sufficient evidence to conclude that glyphosate is not carcinogenic to humans. It is largely excreted unchanged in mammals. It is slightly toxic to wild birds but relatively non-toxic to honeybees. Glyphosate tightly binds to soil so little is leached, notes the noted upstate New York-based university.
Elsewhere, the German Institute for Risk Management reported last year for the EU that, “the available data is contradictory and far from being convincing” with regard to exposure and risk of certain cancers. It concluded that glyphosate was “unlikely to pose a carcinogenic risk to humans.”
Nevertheless, the IARC asked 17 prominent scientists for an opinion on glyphosate’s risk to humans. The committee looked at data from studies published in the U.S., Canada and Sweden since 2001. It concluded that there was evidence that glyphosate can cause tumours in mice and rats in laboratory experiments – and could cause DNA damage in human cells. A forthcoming monograph will classify it as “probably carcinogenic to humans”
Hardly surprisingly, Monsanto disagrees. The company has accused the WHO agency of running “agenda driven bias,” accusing it of cherry picking the evidence. “Unfortunately this review does not meet the standards used by respected agencies around the world,” claimed Philip Miller, Monsanto’s head of global regulatory affairs. While other scientists don’t quite word it that way, there are some raising questions of the IARC’s findings.
Panel chairman Aaron Blair, from America’s National Cancer Institute, pointed out that the panel did not prove that glyphosate definitely caused cancer. “We have looked at, ‘Is there evidence that glyphosate causes cancer?’ and the answer is ‘probably.’ That is different to ‘yes.’”
It has been left to the venerable medical journal
The Lancet to also describe the chemical as “probably carcinogenic to humans.”
