Despite opposition from food-safety and environmental advocates, the U.S. Department of Agriculture deregulated two genetically engineered Monsanto crops last month.

The St. Louis-based company’s genetically modified soybean and cotton seeds are designed to withstand the rarely used weed killer dicamba, meaning farmers could add the herbicide to the commonly used one, glyphosate, which weeds have grown to resist. But besides producing another wave of “super weeds,” critics argue the switch could cause more damage from drift – off-target herbicide use that can cost organic farmers tens of thousands of dollars.

For more on the seeds, also see: "Monsanto inches closer to biggest biotech launch in company’s history"

“As a fourth-generation farmer, I have already witnessed firsthand the dangers of herbicide drift,” a Texas farmer of 6,000 acres wrote in a public comment. “Several [herbicide-resistant] plots were planted in 2014 in the panhandle of west Texas. Every single field of ours showed signs of damage.”

Monsanto projects its genetically engineered soybean and cotton seeds will not be commercially available until 2016. The USDA’s Animal and Plant Health Inspection Service deregulated the varieties in January, but the crops still need to receive approval from the Environmental Protection Agency.

“Because these seeds will be tolerant to the dicamba chemistry, they will enable another tool in farmers’ toolbox – additional modes of herbicide action,” Monsanto representative Miriam Paris said.

For more on the use of GMOs in farming, also see: "With herbicide-resistant crops, farms balance immediate rewards with future risks"

If the seeds do become commercially available, Monsanto estimates dicamba use would increase dramatically, roughly 14-fold in cotton and 88-fold in soybean.

“Herbicides tend to drift onto nearby farms,” said Genna Reed, a researcher with the nonprofit advocacy group Food and Water Watch, based in Washington, D.C. “Basically, for any crop that is not resistant to those particular herbicides, they can really damage the growth of those crops”

“We’re really just exacerbating the problem by continuing the use of more and more chemicals,” she added.

Yet, experts in crop genetics say the new varieties will not change the way farmers use herbicides, pointing out farmers used herbicides, insecticides, fungicides, rodenticides and other types of pesticides long before genetic technology was introduced in the 1990s.

Photo by Robert Holly/Midwest Center for Investigative Reporting

“Most of the acres of corn and soybean were already sprayed with herbicides,” said Brian Diers, a University of Illinois professor who specializes in soybean breeding and genetics.

In 1980, the agriculture industry used about 826 million pounds of pesticide, according to EPA data.

In 2007, the most recent year with data, the industry used 684 million pounds of pesticide.

“In terms of, let’s say, how much herbicides are being used in the Midwest, I don’t think this herbicide tolerant technology has really impacted it,” Diers said.

Specialty farmers among most vocal critics

Before deregulation, the Animal and Plant Health Inspection Service provided more than 180 days for public comment on the Monsanto GMOs. Individuals and groups submitted about 4,800 comments during that window.

Many were from growers concerned about dicamba drift.

“I am very much against the deregulation and usage of dicamba-tolerant soybeans, as I have two vineyards and know the potential negative impact of this chemical product on sensitive crops like my grapes,” an Indiana farmer stated.

“I farm in Rush County, Indiana, and raise corn, soybeans and processing tomatoes,” another farmer commented. “The use of volatile chemicals like 2,4-D and dicamba pose a real threat to my crops, people’s yards and gardens, grapes, and many other plants susceptible to these chemicals.”

Up to 70 million pounds of pesticides are “wasted” because of pesticide drift each year, according to the EPA.

Photo by Darrell Hoemann/Midwest Center for Investigative Reporting

Genetically engineering plants

Modern-day genetics offer crop scientists a few different ways to engineer plants. Monsanto’s dicamba-resistant seeds, for instance, were created using transgenic technology where scientists singled out a particular gene in one plant and moved it into the soybean and cotton.

“Basically, what you do is find a gene that provides a resistance or tolerance in another species,” Diers said. “You isolate the gene, and then you transform that gene into soybeans or whatever crop you may be working with.”

Photo by Robert Holly/Midwest Center for Investigative Reporting

Through this method – which Monsanto also used in its popular Roundup Ready crops – scientists could pick traits from two plants that otherwise would not be able to naturally breed.

Scientists can also use a process known as mutagenesis, where they try to produce a mutation with desirable traits.

Lastly, scientists can simply cross breed naturally occurring plant variations, a process that humans have been turning to since domesticating crops.

“If you would have an herbicide that you’re looking for tolerance or resistance to, the first thing you’d probably do is look for natural variation within the species,” Diers said.

In addition to herbicide concerns, many individuals submitted public comments criticizing genetically engineered food as a whole, calling it “unsafe” and “dangerous.”

That criticism, Diers said, comes from an inherent distrust.

“People are against the GMO technology for a number of reasons,” Diers said. “One is that people just don’t like scientists messing with nature.”