EPA Asks Court To Retract Approval Of Glyphosate-Based Enlist Duo Weed Killer

Environmental regulators have asked a panel of federal judges to revoke approval for the recently introduced herbicide Enlist Duo, which uses the controversial chemical glyphosate that is also found in Roundup, and has recently been linked to a potential risk of cancer for humans. 

In a brief (PDF) filed on November 24, the U.S. Environmental Protection Agency (EPA) asked the U.S. Court of Appeals for the Ninth Circuit to revoke it’s approval of the Dow Chemical pesticide, saying that it has learned that glyphosate and 2,4-D, another ingredient used in the chemical, can amplify each other’s effects.

The EPA warns that the combination could make Enlist Duo more toxic than it anticipated.

The request came as part of an ongoing lawsuit against the EPA brought by the Natural Resources Defense Council, a powerful environmental advocacy group, which is one of the leading critics indicating that the EPA’s decision to approve Enlist Duo in 2014 was based on flawed science.

Glyphosate, the active ingredient most known for its use in Monsanto’s weed killer Roundup, was deemed to be a probably carcinogen in March by the International Agency for Research on Cancer (IARC), an arm of the World Health Organization. The designation has led some countries to ban Roundup and other glyphosate-based pesticides.

The chemical 2,4-D was used in Agent Orange, a defoliant during the Vietnam War, which has been linked to a number of illnesses afflicting veterans of the war.

According to the EPA’s brief, when it first reviewed the available data on Enlist Duo, it determined that there were no indications of synergism between the two chemicals that affected mammals or fish.

“Recently, however, EPA discovered that Dow made claims of ‘synergistic herbicidal weed control’ in its Provisional and Non-provisional patent applications for Enlist Duo. The Provisional application was filed on December 20, 2013, and the final application was filed on December 11, 2014,” the brief states. “Accordingly, in light of the new information regarding the potential synergism of the two Enlist Duo ingredients, EPA seeks a voluntary remand with vacatur to reconsider the Enlist Duo registration.”

The EPA indicates that it contacted Dow after discovering the synergism claims, and warned the company that this would assess how the regulators factored the potential impacts to non-target organisms. Dow responded with more data, which the EPA is still reviewing. However, the preliminary findings led EPA reviewers to conclude that a 30-foot buffer it required around application areas for Enlist Duo may be insufficient.

Glyphosate Cancer Side Effects

The decision comes amid mounting concerns about the human health side effects of glyphosate, and questions about whether exposure to Roundup may increase the risk of non-Hodgkin lymphoma or other cancers.

Roundup is one of the most widely used herbicides, which was introduced by Monsanto in the 1970s. There are now a number of Roundup lawsuits being pursued against Monsanto by former farmers and other individuals exposed to large amounts of the weedkiller, which allege that the manufacturer failed to adequately warn consumers and the agricultural industry that glyphosate may be a human carcinogen.

Monsanto has attempted to dismiss the concerns that Roundup is a human carcinogen, maintaining that the IARC’s conclusions were agenda-driven and based on “junk science.” The manufacturer has said it is convening its own independent panel to review the cancer risks of Roundup.

Consumer use of Roundup began to skyrocket in the mid 1990s, after Monsanto introduced genetically engineered crops to withstand treatment with Roundup, killing the weeds and not the crops. Genetically modified crops, like corn and soybean, are branded as being “Roundup Ready.” Some weeds have developed resistance to glyphosate, thus forcing farmers to use higher quantities of Roundup.

The U.S. Geological Survey estimated agricultural use of glyphosate increased drastically from 110 million pounds in 2002, now to more than 283 million pounds in 2012.

The U.S. Environmental Protection Agency (EPA) announced in April that it plans to address the safety concerns of glyphosate during the regular EPA safety review hearing occurring soon. Researchers warn pesticides are commonly detected in the air, food and water near areas that have been sprayed.