A coalition of environmental groups and farmers is suing the EPA over its approval of Dow AgroSciences’ new crop herbicide, Enlist Duo. The lawsuit alleges inadequate environmental and health assessments by the agency.

Enlist Duo is a combination of glyphosate (better known as Roundup) and 2,4 D. The EPA approved the herbicide for use on October 15. Lawsuits from a coalition of farmers and other environmental groups quickly followed. The effort is led by the Natural Resources Defense Council and The Center for Food Safety.

“We tried our best to work through the administrative process,” says Bill Freese, science policy analyst for The Center for Food Safety. “For two years we filed detailed scientific comments on the agency’s assessment documents and EPA just hasn't listened to us. That's why we've been forced to resort to a lawsuit.”

Enlist Duo is intended for use on corn and soybeans that have been genetically engineered by Dow to withstand its application. This is the heart of the problem, Freese says.

“With the first generation of herbicide-resistant crops — that is, Roundup Ready varieties from Monsanto — there were hardly any weeds that were resistant to Roundup...These crops became quite popular and farmers used glyhposate exclusively. [This] resulted in what people are calling an epidemic of glyphosate-resistant weeds.”

Now, he says, these glyphosate-resistant weeds have become the pretext for introducing the next-generation of GMO crops, such as Dow’s Enlist crops, which are intended to be treated with Enlist Duo. Eventually, weeds will develop resistance to 2,4-D, Freese says. “Unfortunately, there's kind of an acceptance of this ‘pesticide treadmill’ that we really need to get away from,” he insists.

Medical science has clearly demonstrated the risks of 2,4-D exposure, which makes increased use especially concerning, Freese says. Epidemiology studies, which have been replicated repeatedly for decades, show that 2,4-D exposure is linked to higher rates of non-Hodgkin's lymphoma, an immune system cancer that kills about 30 percent of those who contract it. Parkinson's disease has also been linked to 2,4-D, Freese says.

Other studies have looked at the chemical’s adverse effects on children, who are known to be much more sensitive to pesticides than adults because their systems are developing. “EPA is supposed to account for this greater sensitivity in its risk assessments, but unfortunately it failed to do so with Enlist Duo,” Freese says.

The EPA did test 2,4-D on rats and has set limits on its use and application. Freese says the EPA’s tests and restrictions aren't realistic. The agency relies almost completely on tests done on rats and they ignore more relevant medical science that looks at impacts in the real world, Freese claims. What’s more, the tests are often conducted by the manufacturer, not EPA itself.

Public health concerns, of course, are just one aspect of the controversy. Enlist Duo will also have environmental consequences, its opponents contend. The chemical “very effectively kills flowering plants,” Freese says. By extension, it adversely affects essential pollinators such as bees and monarch butterflies.

Flowering plants are the base of the ecosystem, Freese explains, providing habitat and food to animals, including pollinators. In big farming states, where most of the land is taken up with corn and soybean fields, biodiversity is declining. What remains is often found close to corn and soybean fields and studies show reduced populations of nectaring plants around these fields.

This is the other crucial area where EPA got it wrong, Freese argues. “If EPA had really looked at experience with 2,4-D, they would have seen that it's the number one culprit in drift-related crop damage. We know this; there's concrete experience,” he says. Instead, he says, “EPA relies completely on complicated models of pesticide drift that, frankly, were developed by the pesticide industry, and which assume perfect compliance with all sorts of unrealistic conditions.”

For its part, EPA has said only that it “will review the suit and respond appropriately." Dow officials have said they “support EPA’s registration decision and are confident that EPA will prevail in all of the related litigation.”

Enlist Duo’s opponents view the EPA’s decision as a reversal of the effort to move toward more prudent use of toxic chemicals in agriculture. EPA approval means that an already widely-used herbicide will see a three to seven-fold increase in use, Freese says. That is Dow’s own projection, he further notes, which has been confirmed by the USDA. In addition, all the big biotechnology companies are continuing to develop new GMO crops that are resistant to various other herbicides.

“When looked at it in totality, this presages a tremendous increase in overall herbicide use and dependence. We're trying to steer agriculture onto a more sustainable path, where weed control is accomplished with far fewer herbicides.”

This story is based on an interview that aired on PRI's Living on Earth with Steve Curwood.