Thus far, however, EPA appears more likely to side with the chemical firm. The agency has already unveiled a proposal to greenlight the chemical compound, and is expected to make a final decision as early as this summer.
The debate hinges on two questions: Does Dow's weed whacker carry any of the health risks of the wartime weapon? And, long term, would the pesticide create a bigger problem: a new generation of stronger, even harder-to-kill superweeds?
U.S. soldiers sprayed Agent Orange — a mix of two herbicides — over South Vietnam as part of a plan to decimate the jungle and reduce ground cover for North Vietnamese guerrillas. But Agent Orange proved toxic largely because it contained a cancer-causing contaminant that formed when it was manufactured.
Dow says its newly minted product won't be similarly tainted. The company also points out that the Agent Orange ingredient it plans to use has been approved by federal regulators for agricultural use for years.
"The idea that this product is anything like Agent Orange just doesn't hold up," Garry Hamlin, a spokesman for Dow said. "That had a unique contaminant, and it was phased out of use in the U.S. in the 1980s because of those concerns."
Testing conducted by an Agriculture Department researcher using samples collected in the mid-1990s showed that the chemical that plays a starring role in Dow's product can still contain contaminants similar to those found in Agent Orange. The study concluded that there was a "need for more investigation into possible human health effects."
In 2005, EPA concluded a multi-year review of studies into the health and environmental impacts of 2,4-D. The agency determined that, when applied properly, the herbecide met required safety thresholds. In 2014, EPA also stated that contamination concerns were no longer a factor in the manufacture of the chemical.
But the Agent Orange ingredient in question has been linked to thyroid problems. And in April, the International Research Agency on Cancer published a review of epidemiological studies showing that exposure to the chemical was associated with a significant risk of developing non-Hodgkin lymphoma, a form of cancer that affects the lymphatic system.
EPA, meanwhile, has not done a cancer risk assessment of the weed killer because the chemical is not classified as a carcinogen.
"We need to be very cautious when we're registering chemicals, and at this point we really don't have all the data," Ted Schettler, the science director for the Science and Environmental Health Network said.
Green groups also warn that use of the product could spur the creation of the next-generation of superweeds.
Extensive use of a Monsanto-manufactured weed killer called Roundup has given rise to herbicide-resistant superweeds that are ravaging farmland across the country.