Enlist herbicide contains 2,4-D and glyphosate

EXCERPT: In widespread use since the late 1940’s, 2,4-D was also an ingredient in Agent Orange, the highly toxic defoliant used by the U.S. during the war in Vietnam. A number of studies have linked 2,4-D to adverse health effects including cancer, Parkinson’s disease and decreased sperm count.
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With dicamba canceled, legal focus now shifts to Corteva’s Enlist

Adam Allington
Bloomberg Law, June 26, 2020
https://news.bloomberglaw.com/environment-and-energy/with-dicamba-canceled-legal-focus-now-shifts-to-cortevas-enlist

* Corteva’s Enlist likely replacement for dicamba
* Successor faces legal challenge in Ninth Circuit

With the upcoming ban on the most widely used herbicide for soybeans and cotton still being felt across farm country, a parallel legal challenge may end with its logical successor being removed from the market as well.

Agriculture experts say dicamba’s likely replacement would be Corteva Agriscience’s Enlist Duo, which contains a double package of 2,4-dichlorophenoxyacetic acid (2,4-D) and glyphosate, the active ingredient in Roundup.

However, Enlist is facing its own challenge in the Ninth Circuit, which on June 3 required soybean and cotton registrations for three dicamba-based products—Bayer AG’s XtendiMax, BASF SE’s Engenia, and Corteva’s FeXapan—to be canceled by July 31.

Litigation brought by a coalition of advocacy groups claim that, in approving Enlist Duo for use on millions of acres, the EPA violated the Endangered Species Act and the Federal Insecticide Fungicide and Rodenticide Act (FIFRA) “in ways that risk harm to human health, endangered species, and the environment.”

If the court also rules against Enlist, farmers would lose two of their most trusted herbicides in the span of one year. Further complicating the matter is that, in the coming weeks, both farmers and seed companies will be making seed purchases for the 2021 growing season without knowing if the herbicides they go with will be legal to use.

“You could say there’s a bit of a dark cloud over our industry right now,” said Joe Mershman, president of Mershman Seeds, a seed wholesaler based in West Point, Iowa. “Until the courts finalize these rulings, we won’t know what to do.”

Genetically Engineered Seeds

For the vast majority of soybeans and cotton grown in the U.S., farmers rely on seeds that have been genetically engineered to tolerate pesticides. That means the herbicides can be sprayed directly “over the top” on growing crops, without killing the plants.

The pesticide of choice for years was glyphosate. However, as weeds became increasingly resistant to glyphosate, new seed offerings included resistance to other herbicides such as dicamba, 2,4-D, or glufosinate.

In widespread use since the late 1940’s, 2,4-D was also an ingredient in Agent Orange, the highly toxic defoliant used by the U.S. during the war in Vietnam. A number of studies have linked 2,4-D to adverse health effects including cancer, Parkinson’s disease and decreased sperm count.

The case against Enlist is coming from the National Family Farm Coalition, the Center for Biological Diversity, and the Center for Food Safety — the same plaintiffs that prevailed in the dicamba case. A similar challenge by the Natural Resources Defense Council was consolidated before the court. Oral arguments were completed in May 2019.

“The 10,000-foot view in both the dicamba and Enlist cases is about whether EPA supported its pesticide registrations with evidence or not,” said George Kimbrell, legal director for the Center for Food Safety, and co-counsel on the dicamba and Enlist cases.

"Really Two Separate Cases"

In court documents, attorneys for the Environmental Protection Agency argued that a 2017 assessment found that the new use of Enlist Duo on genetically engineered corn, soybean, and cotton crops would “not generally cause unreasonable adverse effects,” and would also have “no effect” on endangered species’ critical habitat.

“2,4-D and glyphosate are both well-studied chemicals that have been registered for use in the United States since the mid-1940s and 1970’s, respectively,” EPA attorneys noted.

As with the dicamba case, Kimbrell says the legal challenge hinges on whether the EPA fully assessed the potential environmental and human health effects from this new use of 2,4-D, and the tendency of both chemicals to vaporize and drift onto nontarget plants.

Other legal experts question how similar the two cases are on substance.

“It’s true that both cases make similar claims, but I also think the facts are sufficiently different that I feel they are really two separate cases,” said Kristine Tidgren, director of the Center for Agricultural Law and Taxation at the University of Iowa.

Both lawsuits allege EPA violations of the same laws while downplaying risks to human health. But there are key differences, Tidgren said.

“For one, the case against dicamba was backed up by almost four years of data showing documented harm caused by drift,” she said. “With enlist, the active ingredients of glyphosate and 2,4-D have had been registered for a while now, and there hasn’t been the same widespread reports of damage.”

Drift Still a Concern

While almost any pesticide has the potential to drift, both dicamba and 2,4-D come from a family of synthetic auxins. The family has a chemical structure that makes them more volatile than other pesticides, which increases the chances of drift, said Joshua Stamper, director of pesticide and fertilizer management division at the Minnesota Department of Agriculture.

“Enlist has the capacity to drift, just like any auxin-based pesticide, especially if it’s not applied under the right conditions,” he said.

The EPA’s failure to address drift risks was a major factor cited by the U.S. Court of Appeals for the Ninth Circuit in vacating the registrations for dicamba. With Enlist use now forecast to increase significantly in soybeans, Stamper says his primary concern rests with exposure to certain specialty crops, particularly grapes and tomatoes, which are sensitive to 2,4-D.

Corteva counters that newer formulations of the chemical have proven to be much less prone to drift.

“Enlist Duo was specifically developed to reduce the potential for drift and offers near-zero volatility, which has been affirmed through years of rigorous testing, extensive EPA evaluation, and real-world use in the field by farmers,” company spokesman Gregg Schmidt said.

According to Bloomberg Intelligence, increased demand for new products, including Enlist, is expected to drive sales for seed and crop protection products, which are targeted to reach $2.9 billion by 2020 and $5.9 billion in 2022.

Other weed scientists told Bloomberg Law that, compared to dicamba, the newer formulation of 2,4-D presents less concern about volatility.

“This risk is still not zero, but I think it’s still much less likely than with the dicamba-based herbicides,” said Amit Jhala, a professor and extension weed specialist at the University of Nebraska.

Health and Environmental Concerns

Plaintiffs attorneys argue in court documents that the EPA relied on insufficient data when it concluded 2,4-D didn’t pose a risk of environmental impacts.

They also argue that the agency didn’t account for “synergistic effects” caused by mixing Enlist with other pesticides that, when combined, are more toxic than the individual components.

“They also haven’t really considered the potentially drastic public health consequences posed by a massive increase of 2,4-D,” said Charles Benbrook, a former research professor who now works as consultant for environmental groups.

While 2,4-D use has remained fairly steady over the past 20 years, the Department of Agriculture has noted that the EPA’s recent approvals of Enlist for over-the-top use on corn, soybeans, and cotton and the dicamba ban should substantially increase its use, Benbrook said.

“It’s very possible that 2,4-D could bypass glyphosate as the most widely used pesticide within a couple years,” he said.

Government lawyers, in court filings, say the EPA determined in 2014 that any human health risks with Enlist are minimal when it’s applied using the required mitigation measures on the label.

Nor, they say, is EPA required to “continuously review evolving science every time an application is submitted for the same uses of an already-registered active ingredient [such as 2,4-D].”

Commercial pesticide applicators point out that even without dicamba and Enlist, farmers would still have other options, such as the old Roundup-ready seeds, or BASF’s LibertyLink product line, which uses glufosinate.

“Over the next three to four months, farmers are going to have to start to make those purchase decisions,” said Jeff Bunting, a crop protection division manager, at Growmark, an Illinois-based agriculture services cooperative.

Without chemical herbicides, farmers would either have to grow less, or use other means of weed control such as increasing tillage.

“But tilling also comes with its own environmental concerns,” Bunting said. “So it’s a real balancing act.”