The EPA gave final approval to a herbicide from Dow AgroSciences on Oct. 15, 2014. The herbicide is called Enlist Duo and will be used with new genetically modified crops from Dow AgroSciences, a unit of Dow Chemical.
Enlist Duo combines the herbicides 2,4-D and glyphosate. It is intended to eliminate severe weed resistance that might otherwise hinder optimal crop production.
Seeds used to grow genetically modified crops approved by the Agriculture Department are engineered to be resistant to Enlist Duo.
At present 2,4-D is the most popular herbicide in the world, and ranks third in the United States where atrazine and glyphosate take first and second place.
Enlist Duo has triggered more than 400,000 comments to the EPA.
Critics of Enlist Duo say that 2,4-D is linked with reproductive problems, non-Hodgkin's lymphoma, Parkinson's disease, and other serious health problems.
It's feared that it may be possible for Enlist Duo to drift over into other farmers' fields, contaminating crops. The ultimate result could be even greater weed resistance for farmers to contend with.
Opponents are concerned about what might happen with an increase of 2,4-D -- of possibly anywhere from 200-600 percent by 2020, according to the USDA -- and want to see more study done.
The nonprofit advocacy organization Environmental Working Group sent the EPA a letter with a list of more than 77,000 names of people who are against approval of Enlist Duo.
Enlist Duo contains both herbicides 2,4-D and glyphosate. Use of Enlist Duo will increase the use of 2,4-D anywhere from two to seven times, according to an estimation from the Center for Food Safety using the USDA's figures.
The Center for Food Safety said that Enlist Duo will create an even bigger problem with weeds that will become impervious to 2,4-D and glyphosate.
Advocacy groups Center for Food Safety and Earthjustice may file lawsuits.
Enlist Duo was designed as competition for Monsanto Co.'s Roundup Ready system. The Roundup Ready system was designed to use glyphosate to kill weeds without harming crops.