Environmental groups are blasting a U.S. Border Patrol project to kill invasive plant life along the Mexican border with an herbicide activists are calling the next Agent Orange -- the Vietnam War-era deforesting chemical later found to cause cancer.

But scientists say the chemical, a relatively common herbicide named Imazapyr, poses little threat to humans or native wildlife.

The Border Patrol plans to spray the herbicide to kill Carrizo cane, which grows in dense thickets along vast stretches of the Rio Grande, which separates the United States and Mexico.

Border Patrol supervisor Roque Sarinana calls the plant "a safety hazard for agents” that enables a drug or human smuggler to cross the border almost undetected.

“The cane grows nearly 10 stems per square feet and up to 30-feet high," Sarinana says. "You could be right next to someone and not even know it.”

Border Patrol agents were scheduled to begin work Wednesday on a $2.1 million pilot project to test methods for killing off the plant along a 1.1-mile stretch of the Rio Grande near Laredo, Texas. Carrizo eradication could eventually be extended the length of the Rio Grande, but for now the project has been put on hold.

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The Border Patrol is considering spraying Imazapyr out of helicopters flying along the river, which has alarmed critics who are comparing it to images of U.S. planes dumping Agent Orange to defoliate the jungle during the Vietnam War.

A number of residential communities lie within a few hundred yards of the spray sites, said spraying opponent Jay Johnson Castro, director of the Rio Grande International Study Center, a non-profit environmental advocacy group based in Laredo.

Johnson agrees that the cane needs to be destroyed — he says it is an invasive species, believed to have arrived with Spanish explorers centuries ago, that draws unhealthy amounts of water from the Rio Grande and kills off other plant life.

But he says there are safer and less destructive ways than spraying to destroy it.

“[Spraying] will kill any and all trees. It will destroy habitat,” he said. “There’s not enough science to know the impact (of Imazapyr) on humans. We used Agent Orange as an example, because for a while it was considered OK by the government.”

But toxicology experts say there's a big difference between Imazapyr and Agent Orange.

“Science has progressed just a few miles since the 1960s in terms of understanding toxicity in the human body,” said Ed Peachy, a horticulturist at Oregon State University.

“This class of herbicide has been around for quite a while, and is not considered a health risk.”

Other critics of the program have expressed concerns about the environmental impact of eradicating the cane. But the U.S. Department of Fish and Wildlife consulted with Border Patrol on protecting native species, and a replanting program is scheduled once the plant is removed.

“There will be some areas without plant coverage, but it’s a short term impact,” said Allan Strand, a field supervisor with Fish and Wildlife.

A spokesman for the Environmental Protection Agency said his organization had no involvement with the project.

Wayne Hamilton, who lectures in ecology at Texas A&M University, said there was a long history of using Imazapyr to kill off invasive species along Texas waterways.

“In those heavy, dense areas along the banks, it would seem to me removal provides an opportunity,” he said. “You might actually have a much improved diversity of plant species that could grow without the complete dominance of one invasive species.”

In 2007 the Border Patrol began construction on 670 miles of border fencing in strategic spots along the U.S.-Mexico boundary, which it argued would make smugglers and illegal immigrants easier to catch. As of December, 500 miles of fencing had been completed.

President Obama announced on Tuesday plans to send more than 500 federal agents to the border and redirect $200 million to fight drug trafficking.