Reexamining IARC’s Classification of Glyphosate

It has been over two years since the International Agency for Research on Cancer (IARC) announced its finding that glyphosate was a probable carcinogen. As a result, glyphosate found its way onto the list of probable carcinogens alongside manufacturing glass, burning wood, emissions from high temperature frying, and work exposure as a hairdresser. But it was a controversial decision and we have since learned a lot about the topic.

Glyphosate is the active ingredient in Round-Up and, generally, considered a pretty benign herbicide. It is the most widely used herbicide around the world because of Round-Up Ready crops, which have been genetically modified to survive its application. As you might expect, the decision was lauded by anti-GMO activists and spurred a flurry of lawsuits against Monsanto, the patent-holder for Round-Up Ready crops. However, the scientific community was a bit confused because the decision ran contrary to an extremely large amount of scientific data on glyphosate. (For a full and complete discussion of the decision, check out my article “Glyphosate as a Carcinogen, Explained.”)

Following IARC’s decision, many governmental agencies, organizations, and groups have come to the oppose conclusion. These include the European Chemical Agency, the European Food Safety Authority, the Canadian Pest Management Regulatory Authority, the Intertek Panel, New Zealand poison experts, and the US Environmental Protection Agency. Even the World Health Organization stood against its own agency to declare that glyphosate is unlikely to cause cancer. Every single time experts took a look at the available data, they found that IARC’s conclusion was just plain wrong.

Yesterday, despite lots of political theater, the European Union announced that it would renew the license for glyphosate for the next 5 years.

In November of 2017, the results of a large long-term study on the use of glyphosate by agricultural workers in the United States found there was no link between exposure to Round-Up and cancer. The study, which was published in the Journal of the National Cancer Institute (JNCI), was part of the Agricultural Health Study (AHS) that has been tracking tens of thousands of agricultural workers, farmers, and their families in Iowa and North Carolina since the 1990’s. It found no association between glyphosate and any solid tumors or lymphoid malignancies. While there was some increased risk of acute myeloid leukemia among those with the highest exposure, the numbers were not statistically significant. In other words, IARC got it way wrong.

To make things worse for IARC, others have discovered that there are things about how IARC conducted its business that make its conclusion a bit suspicious. In fact, when I originally wrote about the decision, I noted that IARC only considered 3 studies, all with questionable methodologies, finding a link between glyphosate exposure and cancer. The rest of the scientific data available at the time came to the opposite conclusion. Now, with the study published in JNCI, the evidence is even more solidly against IARC.

So, where does IARC’s classification stand now?

It seems pretty clear that IARC made a big mistake. Its classification of glyphosate was against the great weight of scientific evidence and the body of that evidence has only grown. Those questioning IARC originally have been vindicated. There was something else at work here, perhaps an agenda against GMOs more than a concern about cancer.

Like so many others, as someone who has been affected by cancer personally, this really disappoints me. I always say that “cancer woo” is the worst kind of woo. It is important that we have a reputable, respected international agency dedicated to cancer research. IARC has hurt its reputation by making the glyphosate classification and that hurts the status of cancer research overall.  Instead of using resources to study real concerns, we’ve been focused on Round-Up.

Unfortunately, this seems to be the standard for those opposed to genetically modified crops. Their campaigns of misinformation and lies cause concern about GMOs that aren’t real. It causes needless worry and steals attention away from things that we should really be talking about.

I feel pretty safe saying glyphosate is not a probable carcinogen.