Too Profitable to Fail? Roundup Ready Glyphosate and Cancer

Ever since early 2015 when the World Health Organization’s cancer assessment experts at the International Agency for Research on Cancer (IARC) determined that glyphosate “probably” caused cancer in humans, the agrochemical industry’s Pro-Cancer Lobby has been on the offensive. For example:

  • California EPA is being sued by Monsanto for referencing IARC's cancer classification as the basis for listing glyphosate on California's list of carcinogens;
  • Individual scientists in the US that served on the IARC panel are now being pressured through legal subpoenas to turn over their meeting notes to Monsanto;
  • US Congress Republicans have challenged the funding for IARC that comes from the US National Institutes of Health (NIH). 

Almost 100 scientists from 25 countries have written to support the IARC evaluation.

It is in this politically-charged atmosphere that the US Environmental Protection Agency (EPA) is now reviewing its registration approval of glyphosate, including an evaluation of its potential cancer risks.  Unfortunately for public health, EPA’s draft assessment concluded that glyphosate is “not likely to be carcinogenic in humans” (see EPA report on glyphosate and cancer Document ID# EPA-HQ-OPP-2016-0385-0094).

EPA’s draft assessment will soon go to its Scientific Advisory Panel for review. I will be attending that meeting – which has already been postponed due to interference and pressure by the agrochemical industry  - and will be providing both written and spoken comments.

My comments to the Scientific Advisory Panel will say:

EPA violated its own Cancer Guidelines by dismissing evidence of non-Hodgkin’s lymphoma (NHL) in people. Even a meta-analysis of many epidemiologic studies that was sponsored by the agrochemical industry reported a statistically significant risk of NHL cancers when glyphosate-exposed individuals were compared with individuals never exposed to glyphosate. IARC’s analysis reported similar results. EPA’s Cancer Guidelines are consistent with calling this “suggestive evidence of carcinogenic potential” for “evidence of a positive response in studies whose power, design, or conduct limits the ability to draw a confident conclusion”.

EPA violated its own Cancer Guidelines when dismissing evidence of elevated cancer in rodent studies. The Cancer Guidelines say either a statistical trend test or a pairwise test is sufficient to establish statistical significance. But, EPA wrongly rejected cancer evidence in experimental rodents that was significant in a trend test if it wasn’t also significant in a pairwise test.

EPA in some cases relied on study summaries provided by the agrochemical industry, without ever having the original studies.

On the flip side, I am pleased that EPA requested more data and more scrutiny to fully evaluate formulated products containing glyphosate, given the toxicity of surfactants like polyethoxylated (POE) tallowamine. In fact, a report submitted under contract to USDA in 1997—twenty years ago—warned that surfactants added to glyphosate products make them much more toxic, and that very little toxicity information is available about the formulated products. Earlier this year, in July 2016, European member states voted to ban POE-tallowamine from glyphosate-based products including Roundup. However, here in the US it continues to be allowed as an “inert” ingredient, essentially unregulated in pesticide products despite possible toxicity.

Terrible harm to farmworkers, pesticide applicators, and the public could result if EPA fails to implement appropriately protective restrictions and regulations on glyphosate-based products.

How can you let EPA know what you think?

The upcoming Scientific Advisory Panel meeting and relevant information in the public Docket (EPA-HQ-OPP-2016-0385) are publicly available – anyone can attend, listen in through the web, and send comments to the EPA Designated Federal Officer, Mr. Steve Knott (

Weed resistance leads to more chemicals

The massive over-use of glyphosate has led to widespread weed resistance, making it much less effective as a weed-killer. But, this has unfortunately not led to a reconsideration of the agricultural practices that created the problem. Instead of replacing extensive use of herbicides on herbicide-tolerant GM engineered seeds with more integrated weed management approaches such as crop rotation and cover crops, Monsanto and other AgroChemical companies are simply pushing new chemical mixes.

For example, in 2014 EPA approved Dow AgroSciences’ new Enlist Duo herbicide, which combines glyphosate and 2,4-D as active ingredients. Even more concerning, this month (November, 2016), EPA proposed expanding its use on GE corn and soybean from the initial 15 states to an additional 19 states, and to an additional crop (cotton).(see NRDC expert Dr. Sylvia Fallon’s blog for more details)

In another debacle, Monsanto rushed to market its new “Xtend” herbicide-tolerant soybean seeds engineered to resist both glyphosate and dicamba. Monsanto began selling the new dicamba-resistant soybean seeds before the use of dicamba for those crops was approved by EPA, leading to illegal uses of the herbicide where farmers are desperate to fight the glyphosate-resistant ‘pigweed’ (Palmer amaranth).

The result of all this herbicide use, misuse, and overuse is an agricultural system that pads the corporate coffers of Monsanto and other heavily-invested agrochemical corporations, while leaving farmers economically challenged and woefully under-prepared, with only one main tool in their toolbox—more toxic chemicals.

To protect the public, farmers and their families, pesticide applicators, and farmworkers, from even more unnecessary and harmful exposures to toxic agrochemicals like glyphosate, EPA and other policy-makers need to change course. Rather than its approve-now-test-later approach, EPA needs to start really look at these pesticide products with a deeper level of scrutiny, including possible toxicity of the ingredients in the final formulated products, the potential impacts of multiple pesticides used in combination with each other, and the long-term impacts on beneficial organisms like pollinators.

USGS Pesticide Use Maps

About the Authors

Jennifer Sass

Senior Scientist, Federal Toxics, Health and Food, Healthy People & Thriving Communities Program

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