Citing the inevitability of “superweeds” and calling the product a “life preserver” for fatally flawed technology, environmentalists urge the EPA not to register a new Dow AgroSciences herbicide for GE corn and soybeans.
Environmentalists warn that an herbicide designed to work with new varieties of genetically engineered (GE) corn and soybeans should not be registered by the Environmental Protection Agency because, like other widely-used herbicides for GE crops, it will gradually promote the emergence of “superweeds” resistant to the new herbicide.
The herbicide at issue is Dow AgroSciences’ Enlist Duo, whose active ingredients are two “old” chemicals: glyphosate (best known by the trade name “Roundup”) and 2,4-D. The herbicide would be applied in fields planted with Enlist Corn and Enlist Soybeans – which Dow has engineered to tolerate the product.
The first commercial applications of 2,4-D date back to the mid-1940s, but the chemical gained notoriety due to its use in a Vietnam War-era defoliant: Agent Orange. Although 2,4-D was not the only herbicide in Agent Orange, the product was contaminated with dioxin — a potent carcinogen — as a byproduct of the production process.
Glyphosate, meanwhile, has long been the dominant herbicide in GE agriculture. Decades of home-and-garden use in addition to agricultural applications have resulted in the inevitable: weeds are becoming resistant to glyphosate, with resistant species having been detected in over half the states.
Killing resistant weeds
The 2,4-D in Enlist Duo is intended to kill all the weeds in a field, whether or not they’ve become resistant to glyphosate. The Agriculture Department is expected to issue a decision “deregulating” Enlist Corn and Enlist Soybeans, which could then be planted anywhere in the United States.
In its April 30 proposal to register Enlist Duo, however, the EPA says it would limit its sale and use (at least initially) to Illinois, Indiana, Iowa, Ohio, South Dakota and Wisconsin. Those are the states where the agency has enough data, it says, to conclude that the new 2,4-D uses won’t put endangered species at risk.
Because one or more of the seven weed species known to resist glyphosate have turned up in 27 states, growers pushed back against the geographic restriction in comments submitted to thepublic docket, which closed on June 30. Conversely, environmental groups have questioned the adequacy of the EPA’s endangered species finding as well as many other agency conclusions supporting its registration proposal.
In fact, the public comments in this docket demonstrate that environmentalist and grower views on GE technology are probably more divisive than ever. Nathan Fields, director of biotechnology and economic analysis for the National Corn Growers Association, told MintPress News that GE herbicide systems offer significant environmental benefits, such as run-off reductions from no-till farming.
He added, however, that some growers have inadvertently promoted weed resistance by misusing glyphosate. “We don’t want what happened with the glyphosate system to happen again, so we have worked with EPA to require best management practices [when applying herbicides to GE crops] with greater specificity than ever before.”
Fields also said that the use of two chemistries — glyphosate and 2,4-D — in a single herbicide greatly reduces the likelihood that a plant will develop resistance to the product.
Environmentalists, however, have lost all patience with GE technology.
The Roundup system has “collapsed”
Jay Feldman, executive director of Beyond Pesticides, told MintPress that providing growers with the chemical equivalent of a “life preserver” only serves to perpetuate a fatally flawed technology.
“The problem of weed and insect resistance to pesticides was predictable when herbicide-tolerant and pesticide-incorporated plants were introduced,” Feldman said. “The promise of genetic engineering for these characteristics has failed as a sustainable practice; first, with increasing glyphosate use — and now the collapse of the system.
“Recently,” Feldman continued, “the state of Texas asked EPA to allow the emergency [meaning non-registered] use of the herbicide propazine on three million acres of cotton because glyphosate was failing. While EPA made the right decision and denied the application because of concerns over water contamination from a triazine [a type of herbicide chemistry], the agency failed to acknowledge that a predictable resistance problem does not qualify as an emergency.”
One of the reasons Roundup became a popular herbicide is that glyphosate is less toxic and less environmentally-persistent than other chemical herbicides. But that’s not the case with 2,4-D. In its proposal to register Enlist Duo, the EPA notes that, in its periodic reviews of 2,4-D, the agency “has required the manufacturer to provide data on dioxin levels in 2,4-D products to confirm that the products can be used safely.”
In herpublic comments on Enlist, Beyond Pesticides staff scientist Nichelle Harriott acknowledges that manufacturing changes have reduced dioxin levels in 2,4-D, but adds, “While dioxin contamination may be the lowest it has been in 2,4-D formulations, the levels have not been reduced to zero. While levels may be very low, expected increases in 2,4-D use means that the frequency of low-level dioxin residues entering the environment will also increase.”
The increase (assuming Enlist Duo is registered) would expand an application volume that’s already very large, in part because 2,4-D is also used to manage weeds along roads and rights-of-way. Under one of the scenarios noted in the finalEnvironmental Impact Statement prepared by the USDA’s Animal and Plant Health Inspection Service for Enlist corn and soybeans, the registration of Enlist Duo could increase 2,4-D applications by 200 to 600 percent by 2020.
APHIS is concerned primarily with such ecological risks as “gene crossing” (in which GE genes find their way into other plants), or the risk that a GE plant could become a “pest” (by crowding out native plant species).
Under those and other criteria spelled out by the Plant Protection Act, APHIS recommended in its final EIS, released on Aug. 6, that the USDA allow the use of Enlist corn and soybeans. Asked by MintPress if the USDA would act on the recommendation by the end of calendar year 2014, an APHIS spokesman “declined to speculate.”
The EPA doesn’t set timelines for its registration decisions. However, in its proposal to register Enlist Duo, the EPA’s Office of Pesticide Programs’ Registration Division points out that the choline salt of 2,4-D — which is used in Enlist Duo — is one of many, long-registered 2,4-D salts, implying that there aren’t many data gaps standing in the way of a registration.
Risk assessment flaws
But environmental groups beg to differ. For example, in its June 4public comments, the Environmental Working Group identifies “major” risk assessment flaws — including “inaccuracies” in the children’s exposure assessment — that warrant a “a completely new risk assessment.” The flaws, says EWG, include the “inexplicable” decision of the EPA “to ignore the inhalation toxicity risks” to children exposed to 2,4-D in spray drift reaching schools and daycare centers.
On itsEnlist website, Dow says that Enlist Duo “will offer ultra-low volatility [and] reduced drift.” However, Beyond Pesticides’ Harriott told MintPress that the EPA has not released volatility data on the particular 2,4-D salt in Enlist Duo, and pointed out that any reductions in the volatility of an active ingredient could be completely offset by the volatility of the product’s “inert” ingredients — the identities of which are shielded as trade secrets under the federal law governing pesticides.
Moreover, Feldman argued, granting registrations to products such as Enlist Duo “is EPA’s typical response to the failures of GE technology for weed and insect management.”
“They register new materials that will escalate the failures, increase pesticide use, and threaten crop productivity in chemical-intensive systems,” he said. “It is this treadmill that EPA should analyze, predict, and reject.”