Twenty years ago scientists debated whether genetically engineering crops to be resistant to herbicides would lead to “superweeds” tolerant of those herbicides.

That debate is no longer hypothetical.

We now know, based on the rapid development of glyphosate-resistant superweeds, that genetically engineering crops to be resistant to additional herbicides will certainly lead to more superweeds. Creating next-generation herbicide-resistant crops amounts to repeating the same mistake as was made with Roundup Ready® crops…only this time around the herbicides that could be sprayed with abandon on the crops genetically engineered to be resistant to them will not be as relatively benign as Roundup® (active ingredient: glyphosate).  (And let’s all hope that glyphosate is that benign because another consequence of spraying glyphosate on vast acreages of resistant crops is that it’s showing up in human and animal urine samples.)

Nevertheless, the U.S. Environmental Protection Agency (EPA) is likely to allow that same mistake to be made again soon.

The agency is poised to register “Enlist Duo,” an herbicide cocktail containing not only glyphosate, the primary cause of our current superweed crisis, but also “2,4-D for use in controlling weeds in corn and soybeans genetically engineered (GE) to tolerate 2,4-D.”

But before EPA allows registration of Enlist Duo, it is seeking comments from the public about doing so. And the agency recently extended the deadline for submitting comments related to registering Enlist Duo until June 30, 2014.

If you’d like to join me in pointing out to the EPA that allowing the spraying of 2,4-D herbicide on U.S. crops will inevitably result in additional superweeds, weeds resistant 2,4-D, you can submit your comments on the agency’s web site. A copy of the comment I submitted to EPA follows.

[For more information on this issue please see “Going Backwards: Dow’s 2,4-D-Resistant Crops and a More Toxic Future,” a publication of the Center for Food Safety.]

May 29, 2014
Comment to the Environmental Protection Agency RE: EPA’s proposed regulatory decision to register Enlist Duo containing glyphosate and the choline salt of 2,4-D for use on corn and soybeans genetically engineered (GE) to tolerate 2,4-D (Docket ID Number: EPA-HQ-OPP-2014-0195)

To Whom It Concerns:
I am a plant molecular geneticist. I was part of the team at Calgene, Inc. that developed, obtained regulatory approval of, and marketed the first genetically engineered (GE) whole food to enter commerce. I believe that, like any powerful technology, crop genetic engineering and any pesticide use it engenders should be regulated on a case-by-case basis. I thank the EPA for this opportunity to comment on EPA-HQ-OPP-2014-0195 (Docket ID).
The cultivation of genetically engineered crops that are tolerant of the herbicide glyphosate, in combination with the use of glyphosate on multi-millions of acres of farmland in the U.S. over the last couple of decades, is a primary reason why, as EPA has stated, “Weeds are becoming increasingly resistant to glyphosate-based herbicides and are posing a problem for farmers.” Based on the requirements EPA proposes to impose on the manufacturer of Enlist Duo, EPA may already be aware that peer-reviewed scientific evidence has been accumulating since at least 2006 (http://www.bioone.org/doi/pdf/10.1614/WT-04-155R.1) indicating that weed management practices associated with crop plants genetically engineered to be resistant to/tolerant of glyphosate have led to substantial increases in plant pests that are resistant to this important herbicide. Weed scientists blame excessive reliance on glyphosate, and the strong selection pressure resulting from that reliance, for the increases in glyphosate-resistant species of Amaranthus, Commelina, Ipomoea and Cyperus (as examples) that have been documented in at least eleven U.S. states. Other peer-reviewed studies have documented biochemical and genetic processes underlying the acquisition of resistance to glyphosate (http://www.pnas.org/content/107/3/1029.full.pdf+html?sid=2ab7260b-932b-476e-b892-6d35ad6f7925). These results of the Roundup Ready crops/glyphosate “commercial experiment” indicate that plant pests can quickly evolve resistance to the herbicide a crop has been genetically engineered to tolerate.
There is no reason to doubt that the lesson learned from glyphosate-tolerant genetically engineered crops, i.e. that plant weeds can quickly evolve resistance to the herbicide a crop has been genetically engineered to tolerate, will also apply to any crop genetically engineered to tolerate being sprayed by any particular herbicide, including 2,4-D. Commercial availability of corn and soybean varieties that are tolerant of 2,4-D, in combination with EPA allowing registration of Enlist Duo, would therefore inevitably lead to excessive reliance on 2,4-D and, consequently, evolution of weeds resistant to that herbicide. If EPA allowed Enlist Duo registration, the question would not be “if resistance develops” among pest plants to 2,4-D but “when.” Therefore, EPA should not allow registration of Enlist Duo.
And while EPA states that “requirements on the manufacturer including robust monitoring and reporting to EPA, grower education and remediation” would “ensure that Enlist Duo successfully manages weed resistance problems,” similar requirements “imposed” by the agency in order to restrict genetically engineered StarLink™ corn to only animal food sources and thereby keep it out of the human food chain failed soon after that product was commercialized. Additionally, the fact that EPA’s current proposal “would allow EPA to take swift action to impose additional restrictions on the manufacturer and the use of the pesticide if resistance develops” is testimony to the agency’s lack of faith in its own ability to “ensure that Enlist Duo successfully manages weed resistance problems” as opposed to creating more of them. Therefore, based on the agency’s track record, the EPA should not allow registration of Enlist Duo.
Were “additional restrictions on the manufacturer and the use of the pesticide” swiftly imposed once it became clear that excessive reliance on glyphosate, and the strong selection pressure resulting from that reliance, was increasing glyphosate-resistant species of Amaranthus, Commelina, Ipomoea and Cyperus weeds in at least eleven U.S. states? (My understanding is that instead of adding restrictions on the use of glyphosate, EPA has increased the allowable levels of glyphosate on various crops.) Even if restrictions were imposed it appears that they were not very effective since the EPA and USDA are now considering Enlist Duo and corn and soybean plants genetically engineered to be tolerant of it as a “solution” to the problem of weeds “becoming increasingly resistant to glyphosate-based herbicides.” But rather than a “solution,” the evidence to date suggests that Enlist Duo in combination with corn and soybean plants genetically engineered to be tolerant of it will inevitably result in 2,4-D-resistant weeds and thereby pose more problems for farmers. Therefore, the EPA should not allow registration of Enlist Duo.
The excessive reliance on 2,4-D that would be encouraged by allowing registration of Enlist Duo for crops genetically engineered to be tolerant to it is also of environmental concern. Multiple peer-reviewed scientific studies have associated 2,4-D (and/or contamination in commercial formulas of same) with increased rates of soft tissue sarcomas (e.g. Hardell and Sandstrom: http://www.nature.com/bjc/journal/v39/n6/index.html) and non-Hodgkins’s lymphoma (e.g. Zahm et al.: http://journals.lww.com/epidem/toc/1990/09000). The commercial availability of corn and soybean varieties that are tolerant of 2,4-D and the inevitable excessive reliance on 2,4-D that will result will lead to significant increases of this carcinogenic compound (or formulas thereof) in the environment. Therefore, on the basis of risk of contamination of the environment, EPA should not allow registration of Enlist Duo.
In sum, 20 years ago environmental scientists and developers of genetically engineered plants could only hypothesize about the chances that cultivating herbicide-resistant crops would result in “superweeds.” But the debate is no longer hypothetical. We now know, based on the rapid development of glyphosate-resistant super weeds, that genetically engineering crops to be resistant to herbicides, and applying massive amounts of those herbicides on those GE crops, will result in superweeds. Creating 2,4-D-resistant crops amounts to repeating the same mistake as was made with Roundup Ready crops…only this time around the herbicide that could be sprayed with abandon on crops genetically engineered to be resistant to it is 2,4-D, a carcinogenic compound. We should have already learned the lesson: GE herbicide-resistant crops are not only not the way to sustainably manage weeds but a way to create more superweeds instead. Please, don’t allow the same mistake to be made again. Let’s get off this dangerous, unsustainable treadmill now. A more sustainable solution would be to encourage the use of an integrated weed management (IWM) program instead.
Thank you for your careful consideration of this matter.
Sincerely,
Belinda Martineau, Ph.D.